KR20200038186A - Optical film, flexible display device and method for producing optical film - Google Patents

Abstract

Provided are an optical film having excellent homogeneity, a flexible image display device providing the optical film, and a manufacturing method of the optical film. The manufacturing method of the optical film comprises the processes of: (a) applying at least one of a polyimide resin and a polyamide resin having a weight average molecular weight of 230,000 or more, a filler having an average primary diameter of 5 to 35 nm, and a varnish containing at least a solvent on a support, drying the same, and forming a coating film; (b) peeling the coating film from the support; and (c) heating the peeled coating film to obtain a film.

Description

Manufacturing method of optical film, flexible display device and optical film {OPTICAL FILM, FLEXIBLE DISPLAY DEVICE AND METHOD FOR PRODUCING OPTICAL FILM}

The present invention relates to an optical film, a flexible display device provided with the optical film, and a method for manufacturing the optical film.

The optical film used in an image display device such as a liquid crystal display device or an organic EL display device requires very high optical homogeneity because the user directly visually recognizes an image displayed through the optical film.

As a method for producing such an optical film, a method of coating a solution containing a volatile solvent and a resin constituting the optical film on a substrate, and then drying and peeling it is used (for example, Patent Document 1). In such a manufacturing method accompanying coating and drying, thickness unevenness and orientation unevenness may occur depending on coating conditions or drying conditions. Even if the film has a level of non-uniformity that cannot be visually confirmed, optical homogeneity is impaired due to the non-uniformity when finally assembled as an optical film in an image display device, resulting in distortion of the image, etc. It may be admitted. Therefore, the film used as an optical film in an image display device requires homogeneity with a very high precision at a level that is difficult to visually confirm. For that reason, there is still a need for further improvement of the optical homogeneity of the film.

As an optical film in which film irregularity is suppressed, for example, in Patent Document 1, in a rectangular region cut out from a projected image of a polyimide-based optical film, a standard deviation σ of gray scale and a binary image of the rectangular region A polyimide-based optical film in which the area of the assay portion is adjusted within a predetermined range is described. Patent Document 2 discloses a transparent film for optics, in which the variation in luminance of transmitted light in the film plane is within 15% of the average luminance in a standard deviation. In Patent Document 3, the light from the light source unit is irradiated onto the grating plate, the light transmitted through the grating plate is projected as a grating image, and the grating image is photographed to quantify the three-dimensional shape of the object to be measured from the distortion of the grating image. A method of measuring the shape by a fringe projection method is described.

International Publication No. 2016/152459 Japanese Patent Application Laid-Open No. 9-48866 Japanese Patent Application Publication No. 2011-226871

However, all of the methods described in the above-mentioned patent documents cannot be said to be methods sufficient for evaluating the optical homogeneity of a film with very high precision required for an optical film as used in an image display device. Since the method described in Patent Document 1 is an evaluation in an analysis area of 1 cm x 5 cm, it is not a method capable of sufficiently evaluating a decrease in optical homogeneity due to non-uniformity occurring in the longitudinal direction. The method described in Patent Literature 2 is not a method capable of accurately evaluating a decrease in optical homogeneity caused by a slight non-uniformity of a small difference in luminance of transmitted light.

Since the method described in Patent Literature 3 is a method for detecting a shape, it is not possible to evaluate a decrease in optical homogeneity due to non-uniformity in refractive index. Therefore, it cannot be said that all the films obtained by evaluating by these methods have sufficient optical homogeneity.

In addition, the optical film is required to be homogeneous in physical properties in addition to the optically homogeneous film. However, in the case of continuously manufacturing an optical film while conveying a film, for example, by a roll-to-roll method or the like, it may be difficult to achieve homogeneous optical properties and physical properties in the MD direction and the TD direction.

This invention is made | formed in view of the subject which the said prior art has, and is used suitably as an optical film in an image display apparatus, The optical film which has high homogeneity, the flexible display device provided with the optical film, and the said film An object of the present invention is to provide a manufacturing method of the.

In order to solve the above-mentioned problems, the present inventors conducted a thorough examination of an evaluation method capable of evaluating the homogeneity of the optical film with high precision and a method of increasing the homogeneity of the optical film. As a result, by focusing on the inverse spatial image obtained by Fourier transform from the projected image by the film projection method, it was found that the optical film satisfying specific requirements has excellent homogeneity, and the present invention has been completed. .

That is, the present invention includes the following suitable aspects.

[1] An optical film comprising a polyimide-based resin and / or polyamide-based resin having a weight average molecular weight of 230,000 or more, and a filler having an average primary particle size of 5 to 35 nm, obtained by projection using the optical film The line profiles in directions h and v that are orthogonal to each other on the film inverse space obtained by Fourier transform of the projected image are referred to as line profiles h and line profiles v, respectively, and are obtained without using the optical film in the projection method. In the background inverse space obtained by Fourier transform of a background image, line profiles in directions h 'and v that are orthogonal to each other are referred to as line profiles h' and line profiles v ', respectively, and line profiles h' from line profiles h. The maximum intensity of the line profile (h-h ') obtained by subtracting is called Y _mh , and the frequency representing the maximum intensity Y _mh is Let X _mh be the maximum intensity of the line profile (v-v ') obtained by subtracting the line profile v' from line profile v, Y _mv , and the frequency representing the maximum intensity Y _mv is X _mv , Y _mh and Y _mv is all 30 or less, and Y _mh , Y _mv , X _mh and X _mv are the following relationships:

Satisfying, optical film.

[2] If the tear strength in the MD direction of the film is E _MD (N / mm) and the tear strength in the TD direction is E _TD (N / mm), the ratio of E _MD to E _TD (E _MD / E _TD ) is 0.93 or more, the optical film according to the above [1].

[3] The optical film according to [1] or [2], wherein the yellowness of the film is 3 or less.

[4] The optical film according to any one of [1] to [3], wherein the filler is silica particles.

[5] The optical film according to any one of [1] to [4], wherein the content of the filler is 5 to 60% by mass relative to the mass of the optical film.

[6] The optical film according to any one of [1] to [5], which is a film for a front plate of a flexible display device.

[7] A flexible display device comprising the optical film according to any one of [1] to [6].

[8] The flexible display device according to [7], further comprising a touch sensor.

[9] The flexible display device according to [7] or [8], further comprising a polarizing plate.

[10] (a) A varnish containing at least a polyimide resin and / or polyamide resin having a weight average molecular weight of 230,000 or more, a filler having an average primary particle diameter of 5 to 35 nm, and a solvent is coated on a support, Drying to form a coating film,

(b) a step of peeling off the coating film from the support, and

(c) Step of heating peeled coating film to obtain film

The manufacturing method of the optical film in any one of said [1]-[6] which contains at least.

ADVANTAGE OF THE INVENTION According to this invention, the optical film which has excellent homogeneity, the flexible image display apparatus provided with the said optical film, and the manufacturing method of the said optical film can be provided.

1 is a schematic view showing an arrangement example in a process of obtaining a projected image.
2 is a schematic view for explaining the arrangement in the process of obtaining a projected image in Examples and Comparative Examples.
3 is a diagram for explaining Y _max , X _max and X _cen in the line profile.
4 is a diagram showing a line profile before normalization obtained from the projected image of Example 1. FIG.
5 is a diagram showing line profiles after normalization obtained from the projected image of Example 1. FIG.
6 is a diagram showing line profiles after normalization obtained from the background image of Example 1. FIG.
7 is a view showing a line profile obtained by subtracting the line profile after normalization obtained from the background image of Example 1 from the line profile after normalization obtained from the projection image of Example 1;
8 is a view showing a line profile obtained by smoothing the line profile obtained by subtracting the line profile after normalization obtained from the background image of Example 1 from the line profile after normalization obtained from the projection image of Example 1;

Hereinafter, embodiment of this invention is described in detail. In addition, the scope of the present invention is not limited to the embodiments described herein, and various changes can be made without departing from the spirit of the present invention.

The optical film of the present invention is an optical film comprising a polyimide resin and / or polyamide resin having a weight average molecular weight of 230,000 or more, and a filler having an average primary particle diameter of 5 to 35 nm. The line profiles in directions h and v that are orthogonal to each other in the film inverse space obtained by Fourier transforming the projected image obtained by the projection method are referred to as line profiles h and v, respectively, and the optical film is not used in the projection method. The line profiles in the directions h 'and v' which are orthogonal to each other on the background inverse space obtained by Fourier transform of the background image obtained without are referred to as line profiles h 'and v', respectively, and the line profiles h 'from the line profiles h. The maximum intensity of the line profile (h-h ') obtained by subtracting is called Y _mh , and the frequency representing the maximum intensity Y _mh is called X _mh . When the maximum intensity of the line profile (v-v ') obtained by subtracting the line profile v' from the line profile v is Y _mv , and the frequency representing the maximum intensity Y _mv is X _mv , Y _mh and Y _mv are both 30 And Y _mh , Y _mv , X _mh and X _mv are the following relationships:

It is an optical film satisfying. Here, the direction h and the direction h 'are directions corresponding to each other, and the direction v and the direction v' are directions corresponding to each other. That these directions correspond means that the azimuth angles are the same. The optical film of the present invention that satisfies the above characteristics has excellent homogeneity and is preferably used as an optical film in an image display device. Here, the optical homogeneity of the optical film is closely related to the planar non-uniformity, thickness non-uniformity, and orientation non-uniformity of the film, and when these non-uniformities occur, the optical homogeneity decreases. Therefore, the optical film of the present invention having excellent optical homogeneity can be said to be a film having reduced non-uniformity such as plane non-uniformity, thickness non-uniformity, and orientation non-uniformity. Moreover, the homogeneity of the physical properties of the optical film is also closely related to the film thickness unevenness and orientation unevenness, and when these unevenness occurs, the homogeneity of the physical properties is deteriorated. The physical properties of the optical film include modulus of elasticity, surface hardness, and tear strength. It can be said that the optical film of the present invention having the above characteristics has a reduced non-uniformity in the same film of these physical properties. In addition, in this specification, the homogeneity of optical homogeneity and physical property is collectively called "homogeneity". In addition, the optical film of the present invention is also simply referred to as a "film".

The film inverse space image obtained by Fourier transforming the projected image obtained by the projection method using the optical film of the present invention, and the background inverse space image obtained by Fourier transforming the background image obtained without using the film in the projection method, respectively, , As long as it is obtained by Fourier transform from the projected image and the background image, but is not particularly limited, for example,

(1) A step of obtaining a projected image by a projection method in which light from a light source is irradiated onto a film and the light transmitted through the film is projected onto a projection surface,

(2) A process of obtaining a background image by projecting light from a light source onto a projection surface without using a film in the projection method of step (1),

And,

(3) The projection image obtained in step (1) and the background image obtained in step (2) are numerically quantified by gray-scale, respectively, and Fourier transform the digitized image data to inverse space (film inverse space and background inverse space) Phase). By evaluating the surface quality of the optical film using the inverse spatial image, it is possible to analyze the unevenness and the period of irregularity.

The method for obtaining the inverse spatial image by Fourier transform from the projected image by the projection method of the film is not particularly limited, but, for example, a method described later for the evaluation process may be used.

Next, (4) each line profile in the two directions orthogonal in the inverse space of the projected image is subtracted from each line profile in the two directions orthogonal in the inverse space on the background image, and the blank corrected line profile is respectively subtracted. the obtaining step, and, (5) a step (4) the maximum intensity of the blank, the corrected line profile obtained from the Y _max (respectively Y _mh and Y _mv), and the maximum intensity in each of the line profiles Y _max (Y _mh and Y _mv The frequency X _max (X _mh and X _mv ) representing) is measured. For example, a case where line profiles are created for each of the horizontal direction (h1 direction) and the vertical direction (v1 direction) passing through the center in the inverse space will be described below. The line profile is represented as a graph showing frequency on the X-axis and intensity on the Y-axis, for example, as shown in FIG. 3. Then, the maximum intensity Y _max in the line profile in the horizontal direction (h1 direction) is referred to as Y _mh1 , and the value X minus the median value X _cen of the total frequency in the blank-corrected line profile from the frequency representing the maximum intensity Y _{mh1 Let max} be X _mh1 . Moreover, the maximum intensity Y _max in the line profile in the vertical direction (v1 direction) is referred to as Y _mv1 , and the value X obtained by subtracting the median value X _cen of the entire frequency in the blank-corrected line profile from the frequency representing the maximum intensity Y _{mv1 Let max} be X _mv1 . In the above example, the horizontal direction (h1 direction) and the vertical direction (v1 direction) passing through the center of space were selected as two orthogonal directions, but the two directions (h direction and v direction) are particularly orthogonal to each other. It is not limited, and may be two directions not passing through the center, and may not be horizontal and vertical directions. In addition, in this specification, the "blank corrected line profile" means each line in the two directions orthogonal in the inverse space of the background image from each line profile in the two directions orthogonal in the inverse space of the projected image. It means the line profile obtained by subtracting each profile. By the above operation, the baseline of the line profile in the inverse space of the projected image can be corrected.

In the optical film of the present invention, the Y _mh and Y _mv are both 30 or less. When Y _mh or Y _mv exceeds 30, it cannot be said that the homogeneity of the optical film is sufficient. In particular, it cannot be said that the optical homogeneity of the film is sufficient to be used as an optical film in an image display device, and it is not possible to sufficiently reduce image distortion and the like. Y _mh and Y _mv are preferably 28 or less, more preferably 26 or less, from the viewpoint of easily increasing the optical homogeneity of the optical film and improving the visibility of the image in the image display device. The smaller Y _mh and Y _mv , the better. The lower limit is not particularly limited, and may be 0 or more, and is usually 1 or more.

In the optical film of the present invention, Y _mh , Y _mv , X _mh and X _mv obtained as described above have the following relationship:

Satisfy. If the value of (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 exceeds 30, the optical homogeneity is not sufficient, and distortion of the screen occurs. Moreover, since the physical homogeneity is not sufficient, for example, when an optical film is used in a flexible display device, sufficient bending resistance or strength may not be obtained in some cases. The upper limit of the value of (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 is preferably 25 or less, more preferably 22 or less, and more preferably 20 from the viewpoint of further increasing the homogeneity of the film. Or less, more preferably 19.5 or less, more preferably 19 or less, more preferably 18 or less, more preferably 17 or less, more preferably 16 or less, more preferably 13 or less, particularly preferably 9 or less to be. The smaller the value of (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 , the better. The lower limit is not particularly limited and may be 0 or more, and is usually 0.5 or more.

In the optical film of the present invention, the median value of the total frequency in the blank-corrected line profile obtained as described above is referred to as X _cen . For example, in the line profile shown in Fig. 3, the total frequency is 90 cm ^-1 , and the median value of 45 cm ^-1 is X _cen . Here, X _cen and X _mh and X _mv obtained as described above have the following relationship:

It is preferable to satisfy. In the above formula, X _m represents X _mh or X _mv , and X _mh It is preferable that both X and _mv satisfy the above expression. The lower limit of | X _m -X _cen | is more preferably 0.5 cm ^-1 or more, and still more preferably 1.0 cm ^-1 or more. Moreover, the upper limit of | X _m -X _cen | is more preferably 8.0 cm ^-1 or less, and more preferably 6.0 cm ^-1 or less. In consideration of productivity and having optical homogeneity not recognized as non-uniformity, it is preferable that X _mh and X _mv are films satisfying the above relationship.

The optical film of the present invention having the above characteristics regarding Y _{mh or the} like has high homogeneity and high homogeneity in physical properties. Therefore, in the optical film of the present invention, if the tear strength in the MD direction of the film is E _MD (N / mm) and the tear strength in the TD direction is E _TD (N / mm), then E to E _TD the ratio of _MD (E _MD / E _TD) is preferably, and more preferably at least 0.95 or 0.93. As the value of E _MD / E _TD approaches 1, it shows that there is no difference between the tear strength in the MD direction and the tear strength in the TD direction of the film, and that the film of the present invention has high homogeneity even in physical properties. Shows. In addition, MD direction is the flow direction of the resin base material at the time of manufacturing the optical film of this invention, and TD direction is a direction perpendicular to the flow direction of a resin base material. The tear strength is measured in accordance with JIS K 7128-1 and the Trouser Test Method. The details of the measurement conditions are as described in Examples.

In the optical film of the present invention, when there is no MD direction and TD direction, or when the MD direction and TD direction are not determined, two directions orthogonal to each other are referred to as A direction and B direction, and the A direction of the optical film is The tear strength is called E _A (N / mm), and the tear strength in the B direction is called E _B (N / mm). In that case, the ratio (E _A / E _B) of _A to E E _B, preferably at least, more preferably at least 0.95 or 0.93. The direction in which the tear strength is lower in the orthogonal two directions is referred to as the A direction, and the direction in which the tear strength is higher is referred to as the B direction. Establish the A direction and the B direction orthogonal to the art A direction with respect to a plurality of directions in the plane of the optical film, the percentage of E _A to E _B obtained for the plurality of direction (preferably 10 or more) (E _A / It is preferable that all of E _B ) are above the said lower limit.

The tear strength of the optical film of the present invention is preferably 0.5 N / mm or more, more preferably 0.7 N / mm or more, and even more preferably 0.9 from the viewpoint of increasing the strength of the optical film and improving durability. It is N / mm or more. Moreover, although the upper limit of the tear strength of the optical film of this invention is not specifically limited, From a viewpoint of flexibility, Preferably it is 10 N / mm or less, More preferably, it is 8 N / mm or less, More preferably, it is 5 N / mm Is below. Moreover, from the viewpoint similar to the above, it is preferably 15 N / mm 2 or more, more preferably 17 N / mm 2 or more, still more preferably 20 N / mm 2 or more, preferably 100 N / mm 2 or less, more preferably It is preferably 70 N / mm 2 or less, and more preferably 50 N / mm 2 or less. It is preferable that the optical film has the tear strength in the TD direction and the MD direction. The tear strength is measured in accordance with JIS K 7128-1, according to the Trouser Test Method. The details of the measurement conditions are as described in Examples.

The optical film of the present invention contains a filler having an average primary particle diameter of 5 to 35 nm. Such an optical film has a high tensile modulus of elasticity in addition to having high homogeneity and transparency. The tensile modulus of the optical film is preferably 4,000 MPa or more, more preferably 5,000 MPa or more, still more preferably 5,500 MPa or more, and particularly preferably 6,000 MPa or more. When the tensile modulus is more than the above lower limit, defects such as pitting are less likely to occur in the optical film, and the strength of the optical film is easily increased and durability is easily improved. The tensile modulus is preferably 10,000 MPa or less, more preferably 9,000 MPa or less. When the tensile modulus is less than or equal to the above upper limit, it is easy to improve the bending resistance of the optical film. In addition, the tensile modulus of the optical film can be measured in accordance with JIS K 7127 at room temperature using a tensile tester, and can be measured, for example, by the method described in Examples.

The yellowness (YI value) of the optical film of the present invention is preferably 3 or less, more preferably 3.0 or less, further preferably 2.5 or less, particularly preferably 2 or less. When the yellowness of the optical film is less than or equal to the above upper limit, it is easy to improve transparency, and for example, it is easy to increase visibility when used in the front panel of a display device. The yellowness is usually -5 or more, preferably -2 or more, more preferably 0 or more, more preferably 0.3 or more, more preferably 0.5 or more, particularly preferably 0.7 or more. The yellowness (YI) was measured in accordance with JIS K 7373: 2006 using a ultraviolet visible near-infrared spectrophotometer and the transmittance of 300-800 nm was determined to obtain the tristimulus values (X, Y, Z). , YI = 100 × (1.2769X-1.0592Z) / Y.

The total light transmittance of the optical film of the present invention is preferably 80% or more, more preferably 85% or more, further preferably 90% or more, particularly preferably 92% or more. When the total light transmittance is equal to or greater than the above lower limit, visibility is easily enhanced when the optical film is assembled to the image display device. Since the optical film of the present invention has high optical homogeneity and exhibits high transmittance, it is possible to suppress luminescence intensity of a display element or the like necessary to obtain a certain brightness, as compared with, for example, a film having a low transmittance. Is done. For this reason, power consumption can be reduced. For example, when the optical film of the present invention is assembled into a display device, a bright display tends to be obtained even if the amount of light of the backlight is reduced, which can contribute to energy saving. The upper limit of the total light transmittance is usually 100% or less. In addition, the total light transmittance can be measured by using a haze computer according to JIS K7361-1: 1997, for example. The total light transmittance may be the total light transmittance in the range of the film thickness of the optical film described later.

The haze of the optical film of the present invention is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, still more preferably 0.5% or less, particularly preferably 0.3% or less. When the haze of the optical film is equal to or less than the above upper limit, the transparency becomes good, and for example, when used in the front plate of an image display device, it is easy to increase the visibility of the image. Moreover, the lower limit of haze is usually 0.01% or more. In addition, haze can be measured using a haze computer according to JIS K7136: 2000.

The film thickness of the optical film of the present invention may be appropriately adjusted depending on the application, but is preferably 25 µm or more, more preferably 27 µm or more, still more preferably 30 µm or more, and preferably 100 µm or less, more It is preferably 90 µm or less, and more preferably 85 µm or less. The film thickness of the optical film can be measured by a film thickness meter or the like, for example, by the method described in Examples.

The optical film of the present invention is an optical film comprising a polyimide-based resin and / or polyamide-based resin having a weight average molecular weight of 230,000 or more, and a filler having an average primary particle diameter of 5 to 35 nm. From the viewpoint of easy to produce an optical film having a high homogeneity having the above-mentioned characteristics regarding Y _{mh or the} like, the optical film of the present invention is preferably a cast film. In the present specification, the cast film is, for example, a solution, dispersion, or melt containing the resin and filler on a suitable support, cast, coated, etc., and coated by heating, cooling, drying, etc. It shows the film obtained by peeling the said coating film from the said support body as needed by making it into flower. The film thus obtained contains at least a polyimide-based resin and / or a polyamide-based resin and a filler having an average primary particle diameter of 5 to 35 nm, and optionally a trace amount of a solvent.

The optical film of the present invention includes a polyimide resin and / or polyamide resin having a weight average molecular weight of 230,000 or more, and a filler having an average primary particle diameter of 5 to 35 nm. The optical film of the present invention may contain one type of polyimide-based resin or polyamide-based resin, or may contain two or more types of polyimide-based resin and / or polyamide-based resin. Further, the optical film of the present invention may contain one type of filler having an average primary particle diameter of 5 to 35 nm, or may contain two or more fillers having an average primary particle diameter of 5 to 35 nm.

<Polyimide resin and polyamide resin>

The optical film of the present invention contains a polyimide resin and / or a polyamide resin having a weight average molecular weight of 230,000 or more. The polyimide-based resin is a resin containing a repeating structural unit containing an imide group (hereinafter sometimes referred to as a polyimide resin), and a repeating structural unit containing both imide groups and amide groups. It represents at least 1 sort (s) of resin chosen from the group which consists of resin to contain (it may be hereafter called a polyamideimide resin). Moreover, a polyamide-type resin shows the resin containing the repeating structural unit containing an amide group.

In one preferred embodiment of the present invention, the polyimide-based resin is a polyimide resin having a structural unit represented by formula (1), or represented by a structural unit represented by formula (1) and formula (2) It is preferable that the paper is a polyamideimide resin having a structural unit. Moreover, it is preferable that polyamide resin is a polyamide resin which has a structural unit represented by Formula (2). Although Formula (1) and Formula (2) will be described below, the description of Formula (1) relates to both polyimide resin and polyamideimide resin, and the description of Formula (2) is poly It relates to both amide resins and polyamideimide resins.

The structural unit represented by Formula (1) is a structural unit formed by the reaction of a tetracarboxylic acid compound and a diamine compound, and the structural unit represented by Formula (2) is formed by a reaction between a dicarboxylic acid compound and a diamine compound. It is a structural unit.

In formula (2), Z is a divalent organic group, independently of each other, and preferably may be substituted with a C1-C8 hydrocarbon group or a fluorine-substituted C1-C8 hydrocarbon group. It is an organic group of 40, and more preferably represents a C4-C40 divalent organic group having a cyclic structure which may be substituted by a C1-C8 hydrocarbon group or a fluorine-substituted C1-C8 hydrocarbon group. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. As an organic group of Z, the following formulas (20), (21), (22), (23), (24), (25), (26), (27), and ( 28) and a group represented by formula (29), a group in which two nonadjacent groups are substituted with hydrogen atoms and a divalent chain hydrocarbon group having 6 or less carbon atoms are exemplified, and the heterocyclic structure of Z is a thiophene ring skeleton. Groups to have are illustrated. From the viewpoint of easily suppressing (reducing the YI value) the yellowness of the obtained optical film, groups represented by formulas (20) to (27) and groups having a thiophene ring skeleton are preferred.

In one embodiment of the present invention, the polyamide resin and the polyamideimide resin may contain plural kinds of Z, and the plural kinds of Z may be the same or different from each other. In particular, from the viewpoint of expressing the high surface hardness and excellent optical properties of the optical film, at least a part of Z is expressed by the formula (3)

[In the formula (3), R ¹ to R ⁸ represent, independently of each other, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and R ¹ to R The hydrogen atoms contained in ⁸ may be each independently substituted with a halogen atom,

A, independently of each other, 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 )-, R ⁹ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbons which may be substituted with a halogen atom,

m is an integer from 0 to 4,

* Represents a bonding hand]

It is preferably represented by.

In formula (3), A is, independently of each other, 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 )-, from the viewpoint of bending resistance of the optical film, preferably -O- or- It represents S-, and more preferably -O-.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are, independently of each other, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 carbon atoms. It represents the aryl group of -12. 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 and 2-methyl-butyl group. , 3-methylbutyl group, 2-ethyl-propyl group, n-hexyl group and the like. Examples of the alkoxy group having 1 to 6 carbon atoms include, for example, methoxy group, ethoxy group, propyloxy group, isopropyloxy group, butoxy group, isobutoxy group, tert-butoxy group, pentyloxy group, hexyloxy group, cyclohexyloxy And timing. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group. From the viewpoint of the surface hardness and flexibility of the optical film, R ¹ to R ⁸ independently of each other 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 And more preferably a hydrogen atom. Here, the hydrogen atoms contained in R ¹ to R ⁸ may be independently substituted with halogen atoms.

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, for example, 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 group, n-heptyl group, n-octyl group, tert-octyl group, n-nonyl group, n-decyl group and the like. And these may be substituted with halogen atoms. Examples of the halogen atom include fluorine atom, chlorine atom, bromine atom, and iodine atom.

In Formula (3), m is an integer in the range of 0 to 4, and when m is within this range, the flexural resistance and elastic modulus of the optical film tend to be good. Moreover, in Formula (3), m is preferably an integer ranging from 0 to 3, more preferably 0 to 2, more preferably 0 or 1, particularly preferably 0. When m is in this range, it is easy to improve the bending resistance and elastic modulus of the optical film. Moreover, Z may contain 1 type (s) or 2 or more types of structural units represented by Formula (3), and from the viewpoint of improving the elastic modulus and flexural resistance of the optical film and reducing the yellowness (YI value), in particular m Two or more types of structural units having different values, preferably two types of structural units having different values of m may be included. In that case, from the viewpoint of expressing the high elastic modulus, bending resistance, and low yellowness (YI value) of the optical film, the resin contains a structural unit represented by formula (3) in which m is 0 in Z. It is preferable, and it is more preferable to further contain the structural unit represented by Formula (3) whose m is 1 in addition to the said structural unit.

In one preferred embodiment of the present invention, the resin has a structural unit represented by formula (3), m = 0, and R ⁵ to R ⁸ are hydrogen atoms. In one more preferred embodiment of the present invention, the resin is a structural unit represented by the formula (3), m = 0, and further, R ⁵ to R ⁸ are hydrogen atoms, and the structural unit (3 '):

It has a structural unit represented by. In this case, it is easy to improve the surface hardness and bending resistance of the optical film, and it is easy to reduce the yellowness.

In one preferred embodiment of the present invention in which the optical film contains a polyamideimide resin, the proportion of the structural unit represented by formula (3) is the structural unit and formula (1) represented by formula (1) of the polyamideimide resin. With respect to the total of the structural units represented by 2), preferably 20 mol% or more, more preferably 30 mol% or more, more preferably 40 mol% or more, particularly preferably 50 mol% or more, and most preferably Is 60 mol% or more, preferably 90 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less. When the proportion of the structural unit represented by the formula (3) is equal to or greater than the above lower limit, it is easy to increase the surface hardness of the optical film, and also to increase the bending resistance and elastic modulus. When the proportion of the structural unit represented by the formula (3) is equal to or less than the above upper limit, it is easy to suppress the increase in viscosity of the resin-containing varnish due to hydrogen bonding between the amide bonds derived from the formula (3) and to improve the processability of the film.

Moreover, when the polyamideimide resin has a structural unit of formula (3) in which m = 1-4, the ratio of the structural unit of formula (3) in which m is 1-4 is the formula (1) of a polyamideimide resin. With respect to the sum of the structural units represented by and the structural units represented by formula (2), 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 70 mol% or less, more preferably 50 mol% or less, particularly preferably 30 mol% or less. When the ratio of the structural unit of the formula (3) in which m is 1 to 4 is more than the above lower limit, it is easy to increase the surface hardness and flex resistance of the optical film. When the proportion of the structural unit of formula (3) in which m is 1 to 4 is equal to or less than the above upper limit, the increase in viscosity of the resin-containing varnish due to hydrogen bonding between the amide bonds derived from formula (3) is suppressed, and the processability of the film is improved. easy to do. In addition, content of the structural unit represented by Formula (1), Formula (2) or Formula (3) can be measured using ¹ H-NMR, for example, or can be calculated from the introduction ratio of a raw material. .

In a preferred embodiment of the present invention, Z in the polyamide resin or the polyamideimide resin is preferably 30 mol% or more, more preferably 40 mol% or more, further preferably 45 mol% or more, particularly Preferably, 50 mol% or more is a structural unit represented by formula (3) in which m is 0 to 4. When the above-mentioned lower limit of Z is a structural unit represented by formula (3) in which m is 0 to 4, it is easy to increase the surface hardness of the optical film, and also to easily increase the bending resistance and elastic modulus. Moreover, 100 mol% or less of Z in polyamide resin or polyamideimide resin should just be a structural unit represented by Formula (3) whose m is 0-4. Moreover, the ratio of the structural unit represented by Formula (3) in which m is 0-4 in resin can be measured using ¹ H-NMR, for example, or can be calculated from the introduction ratio of a raw material.

In one preferred embodiment of the present invention, Z in the polyamide resin or the polyamideimide resin is preferably 5 mol% or more, more preferably 8 mol% or more, still more preferably 10 mol% or more, particularly Preferably, 12 mol% or more is represented by Formula (3) in which m is 1-4. When the above-mentioned lower limit of Z of the polyamide-imide resin is represented by the formula (3) in which m is 1 to 4, the surface hardness of the optical film is easy to increase, and the resistance to bending and elasticity is also easy to increase. In addition, Z is preferably 90 mol% or less, more preferably 70 mol% or less, more preferably 50 mol% or less, particularly preferably 30 mol% or less, where m is 1 to 4 (3 ). When the above upper limit of Z is represented by formula (3) in which m is 1 to 4, the increase in viscosity of the resin-containing varnish due to hydrogen bonding between amide bonds derived from formula (3) in which m is 1 to 4 is suppressed. , It is easy to improve the processability of the film. Moreover, the ratio of the structural unit represented by Formula (3) in which m is 1-4 in resin can be measured using ¹ H-NMR, for example, or can be calculated from the introduction ratio of a raw material.

In Formulas (1) and (2), X independently of each other represents a divalent organic group, preferably a divalent organic group having 4 to 40 carbon atoms, more preferably 4 to 40 carbon atoms having a cyclic structure. Represents a divalent organic group. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. The organic group may have a hydrogen atom in the organic group substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and in this case, the hydrocarbon group and the fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. In one embodiment of the present invention, the polyimide resin or the polyamideimide resin may contain multiple types of X, and the multiple types of X may be the same or different from each other. As X, groups represented by formulas (10), (11), (12), (13), (14), (15), (16), (17) and (18) ; A group in which hydrogen atoms in the groups represented by the formulas (10) to (18) are substituted by a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; And chain hydrocarbon groups having 6 or less carbon atoms.

In formulas (10) to (18), * represents a bond,

V ¹ , V ² and V ³ are, independently of each other, a single bond, -O-, -S-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO _2- , -CO- or -N (Q)-. Here, Q represents a C1-C12 monovalent hydrocarbon group which may be substituted with a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms include the groups described above for R ⁹ .

In one example, V ¹ and V ³ are a single bond, -O- or -S-, and V ² is -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- Or -SO _2- . The bonding position of each ring of V ¹ and V ² and the bonding position of each ring of V ² and V ³ are, independently of each other, preferably a meta position or a para position with respect to each ring, more preferably Is the para position.

Among the groups represented by the formulas (10) to (18), from the viewpoint of easy to increase the surface hardness and bending resistance of the optical film, formulas (13), (14), (15), (16) and The group represented by formula (17) is preferable, and the group represented by formula (14), formula (15) and formula (16) is more preferable. In addition, V ¹ , V ² and V ³ are preferably a single bond, -O- or -S- independently of each other, from the viewpoint of easy to increase the surface hardness and flexibility of the optical film, single bond or -O It is more preferable to be-.

In a preferred embodiment of the present invention, at least a portion of the plurality of Xs in formulas (1) and (2) are represented by formula (4):

[In the formula (4), R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and R ¹⁰ to R ¹⁷ The hydrogen atom contained in may be independently substituted with a halogen atom, and * represents a bond;

It is a structural unit represented by. If at least a part of the plurality of Xs in the formulas (1) and (2) is a group represented by the formula (4), it is easy to increase the surface hardness and transparency of the optical film.

In formula (4), R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ are, independently of each other, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, 1 to 6 carbon atoms Represents an alkoxy group or an aryl group having 6 to 12 carbon atoms. As the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, or the aryl group having 6 to 12 carbon atoms, the alkyl group having 1 to 6 carbon atoms in the formula (3), the alkoxy group having 1 to 6 carbon atoms, or the carbon number 6 to 12 What was illustrated as an aryl group of these is mentioned. R ¹⁰ to R ¹⁷ are, independently of each other, preferably 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, wherein R ¹⁰ to R ¹⁷ The hydrogen atoms contained in may be substituted with halogen atoms independently of each other. 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, independently of each other, 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, transparency, and bending resistance of the optical film, particularly preferably Is 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 group, fluoro group, chloro group or trifluoromethyl group, particularly preferably R ¹¹ and R ¹⁷ are methyl groups or trifluoromethyl groups.

In one preferred embodiment of the present invention, the structural unit represented by formula (4) is represented by formula (4 '):

It is a structural unit represented by, ie, at least a part of the some X is a structural unit represented by Formula (4 '). In this case, the solubility of the polyimide-based resin or the polyamide-based resin in the solvent is increased by the skeleton containing the fluorine element, the storage stability of the varnish containing the resin is easy to improve, and the viscosity of the varnish is reduced. It is easy to do, and it is easy to improve the processability of an optical film. Moreover, it is easy to improve the optical properties of an optical film by the skeleton containing a fluorine element.

In a preferred embodiment of the present invention, X in the polyimide-based resin or polyamide-based resin is preferably 30 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more. It is represented by Formula (4), especially Formula (4 '). When X in the said range in a polyimide-type resin or a polyamide-type resin is represented by Formula (4), especially Formula (4 '), the obtained optical film is transferred to the solvent of a resin by the skeleton containing a fluorine element. It is easy to improve solubility and to improve the storage stability of the varnish containing the resin, and it is easy to reduce the viscosity of the varnish, and it is easy to improve the processability of the optical film. Moreover, the optical properties of the optical film are also easily improved by the skeleton containing the fluorine element. Moreover, preferably, 100 mol% or less of X in the said polyimide-type resin or polyamide-type resin is represented by Formula (4), especially Formula (4 '). X in the said polyamideimide resin may be Formula (4), especially Formula (4 '). The ratio of the structural unit represented by the formula (4) of X in the resin can be measured, for example, using ¹ H-NMR, or can be calculated from the introduction ratio of the raw material.

In Formula (1), Y represents a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbon atoms, more preferably a tetravalent organic group having 4 to 40 carbon atoms having a cyclic structure. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. The organic group is an organic group in which the hydrogen atom in the organic group may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group, and in this case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8. In one embodiment of the present invention, the polyimide-based resin may contain a plurality of types of Y, and the plurality of types of Y may be the same or different from each other. As Y, the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula Group represented by (29); A group in which hydrogen atoms in the groups represented by the formulas (20) to (29) are substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; And a tetravalent chain hydrocarbon group having 6 or less carbon atoms.

In the formulas (20) to (29),

* Represents a bonding hand,

W ¹ is a single bond, -O-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) ₂ -,- Ar-, -SO _2- , -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C (CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which the hydrogen atom may be substituted with a fluorine atom, and specific examples thereof include a phenylene group.

Among the groups represented by formulas (20) to (29), from the viewpoint of surface hardness and flexural resistance of the optical film, groups represented by formulas (26), (28), or (29) are preferred, and formula ( The group represented by 26) is more preferable. In addition, W ¹ is independent of each other, from the viewpoint of easy to increase the surface hardness and bending resistance of the optical film and to reduce the yellowness, single bond, -O-, -CH _2- , -CH ₂ -CH ₂ It is preferable that-, -CH (CH ₃ )-, -C (CH ₃ ) ₂ -or -C (CF ₃ ) _2- , single bond, -O-, -CH _2- , -CH (CH ₃ ) _{-, -C (CH 3) 2} - or -C (CF _{3) 2} - is more preferable, and a single bond, -C (CH _{3) 2} - or -C (CF _{3) 2} - which is more preferably .

In a preferred embodiment of the present invention, at least a portion of the plurality of Y in the formula (1), formula (5):

[In the formula (5), R ¹⁸ to R ²⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and R ¹⁸ to R ²⁵ The hydrogen atoms contained in may be independently substituted with halogen atoms,

* Represents a bonding hand]

It is a structural unit represented by. If at least a part of the plurality of Ys in the formula (1) is a group represented by the formula (5), the solubility of the polyimide-based resin in a solvent is increased, and the viscosity of the varnish containing the polyimide-based resin is easy to reduce, and is optical It is easy to improve the processability of the film. Moreover, it is easy to improve the optical properties of the optical film.

In Formula (5), R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ are, independently of each other, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, 1 to 6 carbon atoms Represents an alkoxy group or an aryl group having 6 to 12 carbon atoms. As the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, or the aryl group having 6 to 12 carbon atoms, the alkyl group having 1 to 6 carbon atoms in the formula (3), the alkoxy group having 1 to 6 carbon atoms, or the carbon number 6 to 12 What was illustrated above is mentioned as an aryl group of. R ¹⁸ to R ²⁵ independently of each other preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R ¹⁸ to R ²⁵ The hydrogen atoms contained in may be substituted with halogen atoms independently of each other. 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, independently of each other, more preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group from the viewpoint of easy to improve the surface hardness, bending resistance, and transparency of the optical film. , 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 And particularly preferably, R ²¹ and R ²² are a methyl group or a trifluoromethyl group.

In one preferred embodiment of the present invention, the structural unit represented by formula (5) is represented by formula (5 '):

It is a group represented by, ie, at least a part of the plurality of Y is a structural unit represented by formula (5 '). In this case, the solubility of the polyimide-based resin in the solvent is improved by the skeleton containing the fluorine element, the storage stability of the varnish containing the resin is easy to improve, and the viscosity of the varnish is easily reduced, and the optical film It is easy to improve the processability. Moreover, it is easy to improve the optical properties of an optical film by the skeleton containing a fluorine element.

In a preferred embodiment of the present invention, Y in the polyimide-based resin, preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more, formula (5), In particular, it is represented by formula (5 '). When Y in the above range in the polyimide-based resin is represented by formula (5), particularly formula (5 '), the solubility of the polyimide-based resin in the solvent is enhanced by the skeleton containing the fluorine element, and the resin is It is easy to reduce the viscosity of the varnish to be contained, and it is easy to improve the processability of the optical film. Moreover, it is easy to improve the optical properties of an optical film by the skeleton containing a fluorine element. Moreover, preferably, 100 mol% or less of Y in the said polyimide resin is represented by Formula (5), especially Formula (5 '). Y in the polyimide-based resin may be formula (5), particularly formula (5 '). The ratio of the structural unit represented by the formula (5) of Y in the polyimide-based resin can be measured, for example, using ¹ H-NMR, or can be calculated from the introduction ratio of the raw material.

The polyimide-based resin or polyamide-based resin includes, in addition to the structural units represented by formulas (1) and (2), structural units represented by formula (30) and / or structural units represented by formula (31) can do.

In formula (30), Y ¹ is a tetravalent organic group, and preferably an hydrogen group in the organic group may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ^1, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula ( Group represented by 29), a group in which hydrogen atoms in the groups represented by formulas (20) to (29) are substituted by a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and a tetravalent carbon number of 6 or less Chain hydrocarbon groups are exemplified. In one embodiment of the present invention, a polyimide resin or a polyamide-based resin may include a plurality of types of Y ^1, Y ¹ of a plurality of kinds it is mutually be the same or different.

In the formula (31), Y ² is a trivalent organic group, and preferably a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ^{2, the} above formulas (20), (21), (22), (23), (24), (25), (26), (27), (28) and A group in which any one of the bonding hands of the group represented by formula (29) is substituted with a hydrogen atom, and a trivalent carbon group having 6 or less chain hydrocarbon groups are exemplified. In one embodiment of the present invention, a polyimide resin or a polyamide-based resin may include a plurality of types of Y ^2, Y ² is a plurality of types may be the same or different from each other.

In Formulas (30) and (31), X ¹ and X ² are, independently of each other, a divalent organic group, and preferably the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is an organic group. As X ¹ and X ^{2, the} above formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17), and formula Group represented by (18); A group in which hydrogen atoms in the groups represented by the formulas (10) to (18) are substituted by a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; And chain hydrocarbon groups having 6 or less carbon atoms.

In one embodiment of the present invention, the polyimide-based resin or polyamide-based resin is a structural unit represented by formulas (1) and / or formula (2), and, optionally, formulas (30) and / or formulas ( 31). Moreover, from the viewpoint of the optical properties, surface hardness and bending resistance of the optical film, in the polyimide-based resin or polyamide-based resin, the structural units represented by formulas (1) and (2) are represented by formula (1) And based on the total structural units represented by formula (2), and optionally formula (30) and formula (31), preferably 80 mol% or more, more preferably 90 mol% or more, and more preferably It is 95 mol% or more. In addition, in the polyimide-based resin or polyamide-based resin, the structural units represented by the formulas (1) and (2) are represented by the formulas (1) and (2), and, optionally, the formulas (30) and / or Or based on the whole structural unit represented by Formula (31), it is 100 mol% or less normally. In addition, the said ratio can be measured using ¹ H-NMR, for example, or can be calculated from the introduction ratio of a raw material.

The weight average molecular weight (Mw) of the polyimide-based resin or polyamide-based resin is 230,000 or more in terms of standard polystyrene. When the weight average molecular weight is lower than 230,000, sufficient bending resistance of the optical film cannot be obtained. From the viewpoint of easy to increase the surface hardness and bending resistance of the optical film, the weight average molecular weight of the polyimide-based resin or polyamide-based resin is preferably 230,000 or more, more preferably 250,000 or more, further preferably 270,000 or more, Especially preferably, it is 300,000 or more. In addition, from the viewpoint of easy to improve the solubility of the polyamide-based resin or polyimide-based resin in a solvent, and to improve the stretchability and processability of the optical film, the weight average molecular weight of the resin is preferably 1,000,000 Below, more preferably 800,000 or less, more preferably 700,000 or less, particularly preferably 500,000 or less. The weight average molecular weight can be obtained by, for example, GPC measurement and by standard polystyrene conversion, for example, by the method described in Examples.

In the polyamideimide resin, the content of the structural unit represented by the formula (2) is preferably 0.1 mol or more, more preferably 0.5 mol or more, and more preferably 1 mol of the structural unit represented by the formula (1). Preferably it is 1.0 mol or more, Especially 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 content of the structural unit represented by Formula (2) is more than the said lower limit, it is easy to raise the surface hardness of an optical film. Moreover, when content of the structural unit represented by Formula (2) is below the said upper limit, it is easy to suppress the thickening by hydrogen bonding between amide bonds in Formula (2), and to improve the workability of an optical film.

In a preferred embodiment of the present invention, the polyimide-based resin or polyamide-based resin contained in the optical film of the present invention can be introduced by, for example, a fluorine-containing substituent or the like, a halogen such as a fluorine atom. It may contain an atom. When the polyimide-based resin or the polyamide-based resin contains a halogen atom, it is easy to improve the elastic modulus of the optical film and reduce the yellowness (YI value). When the elastic modulus of the optical film is high, it is easy to suppress the occurrence of scratches and wrinkles in the film, and when the yellowness of the optical film is low, it becomes easy to improve the transparency and visibility of the film. The halogen atom is preferably a fluorine atom. As a preferable fluorine-containing substituent in order to contain a fluorine atom in a polyimide resin or a polyamide resin, a fluoro group and a trifluoromethyl group are mentioned, for example.

The content of the halogen atom in the polyimide resin or polyamide resin is preferably 1 to 40 mass%, more preferably 5 to 40 mass%, based on the mass of the polyimide resin or polyamide resin. It is mass%, More preferably, it is 5-30 mass%. When the content of the halogen atom is greater than or equal to the above lower limit, the elastic modulus of the optical film is further improved, the absorption rate is lowered, the yellowness is further reduced, and transparency and visibility are more easily improved. When the content of the halogen atom is less than or equal to the above upper limit, it becomes easy to synthesize.

The imidation ratio of the polyimide resin and the polyamideimide resin is preferably 90% or more, more preferably 93% or more, and even more preferably 96% or more. From the viewpoint of easy to increase the optical homogeneity of the optical film, it is preferable that the imidation ratio is more than the above lower limit. Moreover, the upper limit of the imidation rate is 100% or less. The imidation ratio is the ratio of the molar amount of imide bonds in the polyimide resin and the polyamideimide resin to the value twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyimide resin or polyamideimide resin. Shows. Moreover, when a polyimide resin and a polyamideimide resin contain a tricarboxylic acid compound, the value of 2 times the molar amount of the structural unit derived from the tetracarboxylic acid compound in a polyimide resin and a polyamideimide resin, and tricar The ratio of the molar amount of imide bonds in the polyimide resin and the polyamideimide resin to the sum of the molar amounts of the structural units derived from the present acid compound is shown. Moreover, the imidation rate can be calculated | required by IR method, NMR method, etc., For example, in NMR method, it can measure by the method described in an Example.

As the polyimide-based resin and the polyamide-based resin, commercial products may be used. As a commercial item of a polyimide resin, Mitsubishi Gas Chemical Co., Ltd. Neopurim (trademark), Kawamura Industries Co., Ltd. KPI-MX300F etc. are mentioned, for example.

<Resin production method>

The polyimide resin can be produced using, for example, a tetracarboxylic acid compound and a diamine compound as main raw materials, and the polyamideimide resin is mainly composed of, for example, a tetracarboxylic acid compound, a dicarboxylic acid compound, and a diamine compound. It can be produced as a raw material, and the polyamide resin can be produced using, for example, a dicarboxylic acid compound and a diamine compound as main raw materials. Here, it is preferable that the dicarboxylic acid compound contains at least a compound represented by formula (3 ").

In the formula (3 "), R ¹ to R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and R ¹ to The hydrogen atoms contained in R ⁸ may be each independently substituted with a halogen atom,

A is a single bond, -O-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO _{2 represents-} , -S-, -CO- or -N (R ⁹ )-,

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,

m is an integer from 0 to 4,

R ³¹ and R ³² are, independently of each other, a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group or a chlorine atom. Shows.]

In one preferred embodiment of the present invention, the dicarboxylic acid compound is a compound represented by formula (3 ") in which m is 0. As a dicarboxylic acid compound, m is represented by formula (3") in which 0 is In addition to the compound, it is more preferable to use a compound represented by formula (3 ") in which A is an oxygen atom. In another preferred embodiment, in the dicarboxylic acid compound, R ³¹ and R ³² are chlorine It is an atom, and it is a compound represented by Formula (3 "). Moreover, you may use the diisocyanate compound instead of the diamine compound.

As a diamine compound used for manufacture of resin, aliphatic diamine, aromatic diamine, and mixtures thereof are mentioned, for example. In addition, in this embodiment, "aromatic diamine" refers to the diamine in which the amino group is directly bonded to the aromatic ring, and may contain an aliphatic group or other substituents in a part of the structure. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring, but are not limited thereto. Among these, it is preferably a benzene ring. Moreover, "aliphatic diamine" refers to a diamine in which the 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 hexamethylenediamine, and 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornanediamine, and 4,4. And cyclic aliphatic diamines such as' -diaminodicyclohexylmethane. These may be used alone or in combination of two or more.

Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2, Aromatic diamine having one aromatic ring such as 6-diaminonaphthalene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-dia Minodiphenylsulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [ 4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane , 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (sometimes referred to as TFMB), 4,4'-bis (4- Ah Nophenoxy) biphenyl, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene, 9,9-bis (4-amino-3- And aromatic diamines having two or more aromatic rings, such as chlorophenyl) fluorene and 9,9-bis (4-amino-3-fluorophenyl) fluorene. These may be used alone or in combination of two or more.

The aromatic diamine is preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone , Bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) Phenyl] propane, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB), 4,4'-bis (4-aminophenoxy ) Biphenyl, more preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodi Phenylsulfone, 1,4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane , 2,2'-dimethylbenzidine, 2,2'-bis Fluoromethyl) it is 4,4'-diaminodiphenyl (TFMB), 4,4'- bis (4-aminophenoxy) biphenyl. These may be used alone or in combination of two or more.

Among the above diamine compounds, it is preferable to use at least one selected from the group consisting of aromatic diamines having a biphenyl structure from the viewpoints of high surface hardness, high transparency, high flexibility, high bending resistance, and low colorability of the optical film. Consisting of 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl and 4,4'-diaminodiphenyl ether It is more preferable to use one or more selected from the group, and more preferably to use 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB).

Examples of the tetracarboxylic acid compound used in the production of the resin include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic acid anhydride; And aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic acid anhydride. The tetracarboxylic acid compounds may be used alone or in combination of two or more. In addition to the anhydride, the tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound.

Specific examples of the aromatic tetracarboxylic acid anhydride include non-condensed polycyclic aromatic tetracarboxylic acid anhydride, monocyclic aromatic tetracarboxylic acid anhydride, and condensed polycyclic aromatic tetracarboxylic acid anhydride. Examples of the non-condensed polycyclic aromatic tetracarboxylic acid anhydride include 4,4'-oxydiphthalic acid 2 anhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic acid anhydride, 2,2', 3,3'-benzophenonetetracarboxylic acid anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic acid 2 anhydride, 2,2', 3,3'-biphenyltetracarboxylic acid 2 anhydride, 3 , 3 ', 4,4'-diphenylsulfonetetracarboxylic acid anhydride, 2,2-bis (3,4-dicarboxyphenyl) propane 2 anhydride, 2,2-bis (2,3-dicarboxyphenyl) Propane 2 anhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane 2 anhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic acid 2 anhydride (sometimes referred to as 6FDA) , 1,2-bis (2,3-dicarboxyphenyl) ethane 2 anhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane 2 anhydride, 1,2-bis (3,4-dicarboxyphenyl) ) Ethane 2 anhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane 2 anhydride, bis (3,4-dicarboxyphenyl) methane 2 anhydride, bis (2,3-dicarboxyphenyl) methane 2 anhydride, 4,4 '-(p-phenylenedioxy) diphthalic acid 2 anhydride, and 4,4'-(m-phenylenedioxy) diphthalic acid 2 anhydride. . Moreover, as a monocyclic aromatic tetracarboxylic acid 2 anhydride, 1,2,4,5-benzenetetracarboxylic acid 2 anhydride is mentioned, for example, As a condensed polycyclic aromatic tetracarboxylic acid 2 anhydride, for example For example, 2,3,6,7-naphthalenetetracarboxylic acid 2 anhydride is mentioned.

Among these, 4,4'-oxydiphthalic acid 2 anhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic acid 2 anhydride, 2,2', 3,3'-benzophenone tetracarboxylic acid 2 are preferred. Anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic acid 2 Anhydride, 2,2', 3,3'-biphenyltetracarboxylic acid 2 anhydride, 3,3 ', 4,4'-diphenyl Sulfontetracarboxylic acid anhydride, 2,2-bis (3,4-dicarboxyphenyl) propane 2 anhydride, 2,2-bis (2,3-dicarboxyphenyl) propane 2 anhydride, 2,2-bis (3 , 4-dicarboxyphenoxyphenyl) propane 2 anhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic acid 2 anhydride (6FDA), 1,2-bis (2,3-dicarboxyphenyl) ethane 2 Anhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane 2 anhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane 2 anhydride, 1,1-bis (3,4-dicarboxyl) Phenyl) ethane 2 anhydride, bis (3,4-dicarboxyphenyl) methane 2 anhydride, bis (2,3-dicarboxyphenyl) methane 2 anhydride, 4,4 '-(p-phenylenedioxy) diphthalic acid 2 Anhydride and 4,4 '-(m-phenylenedioxy) diphthalic acid 2 anhydride are mentioned, More preferably, 4,4'-oxydiphthalic acid 2 anhydride, 3,3', 4,4'-biphenyl Tetracarboxylic acid anhydride, 2,2 ', 3,3'-biphenyltetracarboxylic acid anhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid 2 anhydride (6FDA), bis (3,4 -Dicarboxyphenyl) methane 2 anhydride and 4,4 '-(p-phenylenedioxy) diphthalic acid 2 anhydride. These may be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic acid anhydride include cyclic or acyclic aliphatic tetracarboxylic acid anhydride. The cyclic aliphatic tetracarboxylic acid anhydride is tetracarboxylic acid anhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic acid anhydride and 1,2,3,4-cyclo Cycloalkanetetracarboxylic acid anhydride, such as butanetetracarboxylic acid anhydride, 1,2,3,4-cyclopentanetetracarboxylic acid anhydride, bicyclo [2.2.2] oct-7-ene-2,3,5 , 6-tetracarboxylic acid anhydride, dicyclohexyl-3,3 ', 4,4'-tetracarboxylic acid anhydride, and positional isomers thereof. These may be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic acid anhydride include 1,2,3,4-butanetetracarboxylic acid anhydride, 1,2,3,4-pentanetetracarboxylic acid anhydride, and the like. Or two or more types can be used in combination. Moreover, you may use combining cyclic aliphatic tetracarboxylic acid anhydride and acyclic aliphatic tetracarboxylic acid anhydride.

Among the above tetracarboxylic acid anhydrides, 4,4'-oxydiphthalic acid 2 anhydride, 3,3 ', 4, from the viewpoint of high surface hardness, high transparency, high flexibility, high flexural resistance, and low colorability of the optical film. 4'-benzophenonetetracarboxylic acid anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic acid 2 anhydride, 2,2', 3,3'-biphenyltetracarboxylic acid anhydride, 3,3 ', 4,4'-Diphenylsulfonetetracarboxylic acid 2 anhydride, 2,2-bis (3,4-dicarboxyphenyl) propane 2 anhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid 2 Anhydrides, and mixtures thereof are preferred, 3,3 ', 4,4'-biphenyltetracarboxylic acid 2 anhydride and 4,4'-(hexafluoroisopropylidene) diphthalic acid 2 anhydride, and mixtures thereof More preferably, 4,4 '-(hexafluoroisopropylidene) diphthalic acid 2 anhydride (6FDA) is more preferable.

As the dicarboxylic acid compound used in the production of the resin, terephthalic acid, 4,4'-oxybisbenzoic acid or an acid chloride compound thereof is preferably used. Other dicarboxylic acid compounds may be used in addition to terephthalic acid, 4,4'-oxybisbenzoic acid or their acid chloride compounds. Examples of other dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, their flexible acid chloride compounds, and acid anhydrides, and may be used in combination of two or more kinds. Specific examples include isophthalic acid; Naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; The dicarboxylic acid compound of the chain hydrocarbon having 8 or less carbon atoms and two benzoic acid are single-bonded, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or phenylene group Linked compounds and their acid chloride compounds. As a specific example, 4,4'-oxybis (benzoyl chloride) and terephthaloyl chloride are preferable, and 4,4'-oxybis (benzoyl chloride) and terephthaloyl chloride are more preferably used in combination.

Further, the polyimide-based resin may be obtained by further reacting tetracarboxylic acid and tricarboxylic acid and their anhydrides and derivatives in addition to the above tetracarboxylic acid compound in a range that does not impair various physical properties of the optical film. .

As a tetracarboxylic acid, the water adduct of the anhydride of the said tetracarboxylic acid compound is mentioned.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acid, aliphatic tricarboxylic acid, and their flexible acid chloride compounds and acid anhydrides, and may be used in combination of two or more. Specific examples include anhydride of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalene tricarboxylic acid-2,3-anhydride; And a compound in which phthalic anhydride and benzoic acid are connected by a single bond, -O-, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or a phenylene group. .

In the production of the resin, the amount of the diamine compound, the tetracarboxylic acid compound and / or the dicarboxylic acid compound used can be appropriately selected depending on the ratio of each structural unit of the desired polyimide-based resin and polyamide-based resin.

In the production of the resin, the reaction temperature of the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound is not particularly limited, but is, for example, 20 to 200 ° C, preferably 25 to 100 ° C. Although the reaction time is not particularly limited, it is, for example, about 30 minutes to 10 hours. If necessary, the reaction may be performed under an inert atmosphere or a reduced pressure condition. In a preferred aspect, the reaction is carried out under stirring under normal pressure and / or inert gas atmosphere. Moreover, it is preferable to perform reaction in a solvent inert to reaction. The solvent is not particularly limited as long as it does not affect the reaction, but, for example, water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy- Alcohol-based solvents such as 2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; Ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, γ-valerolactone, propylene glycol methyl ether acetate and ethyl lactate; Ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; Aliphatic hydrocarbon solvents such as pentane, hexane and heptane; Alicyclic hydrocarbon solvents such as ethylcyclohexane; Aromatic hydrocarbon solvents such as toluene and xylene; Nitrile solvents such as acetonitrile; Ether-based solvents such as tetrahydrofuran and dimethoxyethane; Chlorine-containing solvents such as chloroform and chlorobenzene; Amide solvents such as N, N-dimethylacetamide and N, N-dimethylformamide; Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; Carbonate-based solvents such as ethylene carbonate and propylene carbonate; And combinations thereof (mixed solvents). Among these, an amide solvent can be suitably used from the viewpoint of solubility.

In the imidation step in the production of a polyimide-based resin, imidization can be performed in the presence of an imidization catalyst. Examples of the imidization catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine and ethyldibutylamine; Alicyclic amines (monocyclic) such as N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine; Alicyclic amines (polycyclic) such as azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2.2] octane, and azabicyclo [3.2.2] nonane; And pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline), 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine And aromatic amines such as 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline. . Moreover, it is preferable to use an acid anhydride with an imidation catalyst from a viewpoint that it is easy to accelerate an imidation reaction. Examples of the acid anhydride include conventional acid anhydrides used in the imidization reaction, and specific examples thereof include aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic acid anhydrides such as phthalic acid.

The polyimide-based resin and polyamide-based resin are isolated by conventional methods, for example, separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a separation means combining them. (I) (separated and purified) may be used, and in a preferred embodiment, a large amount of alcohol such as methanol is added to the reaction solution containing the transparent polyamideimide resin, and the resin is precipitated, followed by concentration, filtration, drying, and the like. By doing so, it can be isolated.

<Filler>

The optical film of the present invention contains a filler having an average primary particle diameter of 5 to 35 nm. The optical film of the present invention containing a filler having an average primary particle diameter of 5 to 35 nm is an optical film having both transparency and optical homogeneity, high elastic modulus and strength, and is particularly suitable for use in flexible display devices and the like. When the average primary particle diameter of the filler is smaller than 5 nm, it is difficult to obtain an optical film in which the filler is uniformly dispersed because the particles of the filler are likely to aggregate. As a result, the optical homogeneity of the optical film and the homogeneity of the physical properties are impaired, and the transparency, elastic modulus, and strength of the optical film tend to decrease. When the average primary particle diameter of the filler is larger than 35 nm, the optical properties of the filler itself affect the optical properties of the optical film, and the transparency of the optical film cannot be sufficiently increased. From the viewpoint of easy to increase the homogeneity, transparency, modulus, and strength of the optical film, the average primary particle diameter of the filler is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more. In addition, from the viewpoint of easily increasing the transparency of the optical film, the average primary particle size of the filler is preferably 30 nm or less.

The average primary particle size of the filler can be measured by the BET method. Specifically, the specific surface area (BET specific surface area) measured by the BET method (nitrogen adsorption BET method) can be calculated in terms of an average primary particle diameter. Here, if the average primary particle size is d (nm), the density of the filler is ρ (g / cm 3), and the BET specific surface area is S (m 2 / g), then d = 6000 / (S × ρ) is established. For example, when the filler is silica, the average primary particle size can be calculated from the BET specific surface area from the equation d = 2070 / S. Further, the primary particle diameter (average primary particle diameter) may be measured by image analysis of a transmission electron microscope (TEM) or a scanning electron microscope (SEM). The average primary particle diameter of the filler contained in the optical film may be the average primary particle diameter of the filler used as a raw material, or may be the average primary particle diameter measured from the optical film. When measuring the average primary particle diameter of the filler from the optical film, the average primary particle diameter of the filler in the optical film may be measured by image analysis of a transmission electron microscope or a scanning electron microscope using the film as a measurement sample, and a film is required. Therefore, the pulverized and crushed film is dissolved in a soluble solvent (e.g., γ-butyrolactone) in the film, and the dispersed particles are subjected to a transmission electron microscope (TEM) or a scanning electron microscope (SEM). ), The filler may be taken out from the film, dried, and the average primary particle diameter may be calculated from the BET specific surface area in the same manner as above. When the average primary particle diameter is measured by, for example, image analysis of an electron microscope, the average value of the result of measuring the primary particle diameter for each of the 100 particles present in a certain area may be the average primary particle diameter.

Examples of the filler include organic particles, inorganic particles, and the like, and preferably inorganic particles. Examples of the inorganic particles include metal oxide particles such as silica, zirconia, alumina, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide, and metal fluorides such as magnesium fluoride and sodium fluoride. Particles, etc. are mentioned, and among these, silica particles, zirconia particles, and alumina particles are preferable, from the viewpoint of improving the elastic modulus and / or tear strength of the obtained optical film and improving the impact resistance, and more Preferably, silica particles are used. These fillers may be used alone or in combination of two or more.

The content of the filler having an average primary particle size of 5 to 35 nm is preferably 5% by mass or more, more preferably 10% by mass or more, more preferably 15% by mass or more, more preferably with respect to the mass of the optical film. Is 20% by mass or more, more preferably 25% by mass or more, particularly preferably 30% by mass or more. When the content of the filler is more than the above lower limit, it is easy to improve the impact resistance and durability of the optical film. The content of the filler having an average primary particle diameter of 5 to 35 nm is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less with respect to the mass of the optical film. When the content of the filler is less than or equal to the above upper limit, haze and yellowness of the optical film are easy to reduce, and transparency and optical properties are easy to improve, and bending resistance is easily improved.

<UV absorber>

The optical film of the present invention may contain at least one ultraviolet absorber. The ultraviolet absorber can be appropriately selected from those commonly used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light having a wavelength of 400 nm or less. Examples of the ultraviolet absorber include at least one compound selected from the group consisting of benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds, and triazine-based compounds. The ultraviolet absorber may be used alone or in combination of two or more. Since the deterioration of the resin is suppressed by the optical film containing an ultraviolet absorber, visibility can be improved when the optical film of the present invention is applied to an image display device or the like. In the present specification, the "system compound" refers to a derivative of a compound to which the "system compound" is attached. For example, "benzophenone type compound" refers to a compound having a benzophenone as a parent skeleton and a substituent bound to benzophenone.

When the optical film of the present invention contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably 0.01 to 10 parts by mass, more preferably 1 to 8 parts by mass, more preferably with respect to the mass of the resin contained in the optical film. It is preferably 2 to 7 parts by mass. When the content of the ultraviolet absorber is more than the above lower limit, it is easy to improve the ultraviolet absorbency. When the content of the ultraviolet absorber is equal to or less than the above upper limit, decomposition of the ultraviolet absorber due to heat at the time of manufacturing the substrate can be suppressed, and it is easy to improve optical properties, for example, to reduce haze.

<Other additives>

The optical film of the present invention may further contain additives other than fillers and ultraviolet absorbers. Examples of other additives include colorants such as antioxidants, mold release agents, stabilizers, and bluening agents, flame retardants, pH adjusters, silica dispersants, lubricants, thickeners, and leveling agents. When other additives are contained, the content thereof may be preferably 0.005 to 20 parts by mass, more preferably 0.01 to 15 parts by mass, and even more preferably 0.1 to 10 parts by mass relative to the mass of the optical film.

<Manufacturing method of optical film>

The method for producing the optical film of the present invention having the above characteristics is not particularly limited, for example, the following steps:

(a) a polyimide-based resin and / or polyamide-based resin having a weight average molecular weight of 230,000 or more, a filler having an average primary particle diameter of 5 to 35 nm, and a varnish containing at least a solvent are coated on a support and dried, The process of forming a coating film,

(b) a step of peeling off the coating film from the support, and

(c) Step of heating peeled coating film to obtain film

It can be manufactured by a production method comprising at least. The present invention also provides a method for manufacturing an optical film, which includes at least the above steps.

The manufacturing method of the optical film of this invention is after process (c),

(d) The line profiles in directions h and v that are orthogonal to each other on the film inverse space obtained by Fourier transforming the projected image obtained by the projection method using the obtained film are referred to as line profiles h and line profiles v, respectively, In the projection method, the line profiles in the directions h 'and v' which are orthogonal to each other in the background inverse space obtained by Fourier transforming the background image obtained without using the film are line profiles h 'and line profiles v', respectively. And the maximum intensity of the line profile (h-h ') obtained by subtracting the line profile h' from the line profile h is called Y _mh , and the frequency representing the maximum intensity Y _mh is called X _mh , and the line profile from the line profile v. The maximum intensity of the line profile (v-v ') obtained by subtracting v' is Y _mv , and the frequency representing the maximum intensity Y _mv is X _mv Is based on the values of Y _mh and Y _mv and (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 calculated from Y _mh , Y _mv , X _mh and X _mv , Process to evaluate the film

You may further include.

The varnish used in the above step (a) contains at least a polyimide-based resin and / or polyamide-based resin having a weight average molecular weight of 230,000 or more, a filler having an average primary particle diameter of 5 to 35 nm, and at least a solvent. Here, the viscosity (cps) of the varnish and the solid content concentration (mass%) of the varnish are as follows:

It is preferable to satisfy.

First, the step (a) of applying the varnish on a support and drying it to form a coating film will be described. Examples of the resin and filler contained in the varnish include the resins and fillers described above as resins and fillers included in the optical film of the present invention. In addition, the varnish may contain the ultraviolet absorber and other additives described above.

The solvent contained in the varnish is not particularly limited as long as the resin can be dissolved. Examples of such a solvent include amide solvents such as N, N-dimethylacetamide (DMAc) and N, N-dimethylformamide; lactone-based solvents such as γ-butyrolactone (GBL) and γ-valerolactone; Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; Carbonate-based solvents such as ethylene carbonate and propylene carbonate; And combinations thereof (mixed solvents). Among these, an amide-based solvent or a lactone-based solvent is preferable from the viewpoint of easy to increase the homogeneity of the optical film, especially the optical homogeneity. These solvents may be used alone or in combination of two or more. Moreover, the varnish may contain water, an alcohol solvent, a ketone solvent, an acyclic ester solvent, an ether solvent, and the like. The solid content concentration of the varnish is preferably 1 to 25% by mass, more preferably 5 to 20% by mass.

The varnish can be prepared by mixing and stirring the above resin, filler, solvent and UV absorber and other additives used as needed. For example, a reaction solution of a polyimide-based resin or a polyamide-based resin obtained by reacting the above-described dicarboxylic acid compound, tetracarboxylic acid compound, and / or diamine compound, and other raw materials described above is a solvent and a case Varnish may be prepared by mixing and stirring with other additives according to the conditions. The varnish may be prepared by isolating a polyimide-based resin or a polyamide-based resin from the reaction solution and mixing with a solvent, etc., a solution or solid of a polyimide-based resin or a polyamide-based resin is purchased, and mixed with a solvent and the like as necessary. By doing so, the varnish may be prepared. Moreover, when using silica as a filler, the varnish is used using a silica sol in which the dispersion of the silica sol containing silica is replaced by a solvent in which the resin is soluble, for example, a solvent used in the preparation of the following varnish. You may prepare.

The viscosity (cps) of the varnish prepared as described above and the solid content concentration (mass%) of the varnish are not particularly limited, but from the viewpoint of easy to obtain the film of the present invention having excellent homogeneity, they have the following relationship:

It is preferable to satisfy. Here, the viscosity (cps) of the varnish is measured at 25 ° C using an E-type viscometer according to JIS K8803: 2011. Moreover, the solid content concentration of the varnish indicates the concentration (mass%) of the resin, filler, and additives contained in the varnish, and is calculated from the mass of the solid content contained in the varnish based on the total mass of the varnish. The product of the viscosity of the varnish represented by the above formula and the solid content concentration of the varnish is preferably 3,000 or more, more preferably 3,500 or more, from the viewpoint of easy to increase the optical homogeneity of the film. Although the upper limit of the product of the viscosity of the varnish represented by the above formula and the solid content concentration of the varnish is not particularly limited, from the viewpoint of handling of the varnish, it is preferably 10,000 or less, more preferably 7,000 or less.

The viscosity of the varnish is preferably 5,000 to 60,000 cps, more preferably 10,000 to 50,000 cps, more preferably 15,000 to 45,000 cps. When the viscosity of the varnish is more than the above lower limit, the effect of the present invention is easily obtained, and it is preferable from the viewpoint of ease of handling of the varnish that it is less than or equal to the above upper limit.

The solid content concentration of the varnish is preferably 5 to 25% by mass, more preferably 7 to 23% by mass, and even more preferably 9 to 20% by mass. It is preferable from the viewpoint of obtaining a thick film thickness that the solid content concentration of the varnish is above the lower limit, and it is preferable from the viewpoint of ease of handling of the varnish that it is below the upper limit.

As a support body, a resin base material, a stainless steel belt, a glass base material etc. are mentioned, for example. As a support, it is preferable to use a resin film substrate. Examples of the resin film substrate include polyethylene terephthalate (PET) films, polyethylene naphthalate (PEN) films, cycloolefin-based (COP) films, acrylic films, polyimide films, and polyamideimide films. Among them, from the viewpoint of excellent smoothness and heat resistance, a PET film, a COP film, and the like are preferable, and from the viewpoint of adhesiveness and cost of the optical film, a PET film is more preferable.

The thickness of the support is not particularly limited, but is preferably 50 to 250 μm, more preferably 100 to 200 μm, and even more preferably 150 to 200 μm. When the film thickness of the support is less than or equal to the above upper limit, it is preferable because it is easy to suppress the production cost of the film. Moreover, it is preferable that the film thickness of the support is greater than or equal to the above lower limit because it is easy to suppress curl of the film that may occur in the step of removing at least a part of the solvent. Here, the film thickness of the support is measured by a contact-type film thickness meter or the like. From the viewpoint of improving the surface quality of the film and making it easy to produce the optical film of the present invention, the film thickness distribution of the support is preferably ± 3 μm or less, more preferably ± 2.5 μm or less, and more preferably ± 2 µm or less. The film thickness distribution of the support is measured by measuring the film thickness in at least 20 places of the film, calculating the average film thickness in 20 places, and calculating the film thickness and average film thickness in each place according to the measuring method of the film thickness. Calculate from the difference between

When applying the varnish on the support, you may apply to the support by a known coating method. As a known coating method, for example, a roll coating method such as a wire bar coating method, reverse coating, gravure coating, die coating method, comma coating method, lip coating method, spin coating method, screen coating method, fountain coating method, di And a ping method, a spraying method, and a flexible molding method.

Next, the coating film can be formed by drying the coating film of the varnish applied on the support. Drying is performed by removing at least a part of the solvent from the varnish coating film, and the drying method is not particularly limited. For example, drying may be performed by heating the coating film of the varnish applied on the support. In the following, drying in step (a) is also referred to as "first drying", and the coating film formed on the support after drying is also referred to as "dry coating". The dry coating film may be a coating film in which all the solvents contained in the varnish are dried, or a coating film in a semi-dry state in which some solvents are dried. If necessary, the first drying may be performed under an inert atmosphere or under reduced pressure. It is preferable to perform the first drying at a relatively low temperature over time. When the first drying is performed at a relatively low temperature, the values of Y _mh and Y _{mv in} the above formula are easily reduced, and the values of (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 are reduced. It is easy to do, and it is easy to increase the optical homogeneity of the optical film. When drying by heating, the heating temperature during the first drying is preferably 50 to 150 ° C, more preferably 60 to 130 ° C, and still more preferably 70 to 120 ° C. The time for the first drying is preferably 5 to 60 minutes, more preferably 10 to 40 minutes. The first drying may be performed under conditions of one step or multiple steps. When drying is performed under conditions of multiple stages, preferably, in each stage, drying may be performed under the same or different temperature conditions and / or drying time, for example, steps 2 to 10, preferably 3 Drying may be performed under the conditions of -8 steps. When the first drying is performed under conditions of multiple stages, it is easy to increase the optical homogeneity of the optical film. In a preferred embodiment of the present invention in which the first drying is performed under the conditions of three or more steps, it is preferable that the temperature profile of the first drying includes an elevated temperature and a reduced temperature. As such a temperature profile, for example in the case of four steps, the temperature of the first drying is, in order, 70 to 90 ° C (first temperature), 90 to 120 ° C (second temperature), and 80 to 120 ° C (third) Temperature) and 80 to 100 ° C (fourth temperature). In this example, the temperature of the first drying is raised from the first temperature to the second temperature, and then the temperature is decreased from the second temperature to the third temperature, and further from the third temperature to the fourth temperature. Here, the time for the first drying is 5 to 15 minutes in each step, for example. It is preferable to perform 1st drying so that the residual amount of the solvent of a dry coating film becomes 5-15 mass% with respect to the mass of a dry coating film, More preferably, it is 6-12 mass%. When the residual amount of the solvent is within the above range, it is easy to decrease the values of Y _mh and Y _mv in the above formula of the optical film, and to decrease the value of (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 easy. Moreover, in the following process (b), it is easy to improve peelability at the time of peeling a coating film from a support body. As a result, it is easy to increase the homogeneity of the optical film. The residual amount of the solvent is lowered by increasing the drying temperature of each step and increasing the drying time. Therefore, it is possible to adjust the drying temperature and the drying time so as to have the residual amount of the solvent in a desired range, thereby improving the homogeneity of the optical film.

Next, in step (b), the dried coating film is peeled from the support. The peeling method is not particularly limited, and the film may be removed by moving the coating film while the support is fixed, or may be removed by moving the support while the coating film is fixed, and peeling is performed by moving both the coating film and the support. You may do it.

Next, in the step (c), the film of the present invention can be obtained by heating the coating film peeled in the step (b). The heating step in step (c) is hereinafter also referred to as "second drying" or "post bake", and the coating film peeled in step (b) is also referred to as "peel coating film" below. In step (c), it is preferable to perform post-baking in a state in which the release coating film is stretched in the in-plane direction. The heating temperature during the second drying is preferably 150 to 300 ° C, more preferably 180 to 250 ° C, and even more preferably 180 to 230 ° C. The heating time in the second drying is preferably 10 to 60 minutes, more preferably 30 to 50 minutes. When the post-baking treatment is performed while the dry coating film is uniformly stretched in the in-plane direction, it is easy to lower the values of Y _mh and Y _mv in the above formula of the optical film, and (Y _mh + Y _mv ) / (X _mh + X _mv ) It is easy to decrease the value of ^1/2 .

In the step (3), when heating the coating film, it is preferable to apply a tension to the coating film and perform heating in a state where the coating film is stretched in the in-plane direction. By heating while applying tension, it is easy to suppress a decrease in the optical homogeneity of the optical film obtained by shrinkage of the coating film due to drying, and as a result, decrease the values of Y _mh and Y _mv in the above formula of the optical film. It is easy, it is easy to lower the value of (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 , and it is easy to increase the homogeneity of the optical film, especially the optical homogeneity.

In one embodiment of the present invention, in the case of manufacturing the optical film in a roll-to-roll manner, the peeling coating film may be dried while being stretched in the conveying direction. Moreover, when manufacturing an optical film in a single leaf type, you may dry it in the state extended uniformly in the in-plane direction. The conveyance speed in the roll-to-roll system is preferably from 0.1 to 5 m / min, more preferably from 0.5 to 3 m / min, and even more preferably from the viewpoint of easy to increase the homogeneity of the obtained optical film, particularly optical homogeneity. It is 0.7-1.5 m / min.

For example, in the case of manufacturing the optical film by the roll-to-roll method, the optical film of the present invention can be obtained by heating while conveying a long strip-shaped coating film having a predetermined width. Here, in the case of heating while applying tension to the coating film, the method is not limited at all, but, for example, the ends of the long belt-shaped film to be conveyed are each gripped and held. While conveying the film, the width of the gripped film is a predetermined distance, and for example, heat treatment is performed while conveying the inside of the dryer. At this time, the ratio of the width of the film after heat treatment (however, the gripping portion is not included in the width) to the width of the film before heat treatment (however, the gripping portion is not included in the width) is set to 1.1 or less, and the dryer It is preferable to perform the process (3) by releasing the gripping of the resin film from.

The ratio of the width of the film after the heat treatment (however, the gripping part is not included in the width) to the width of the film before the heat treatment (however, the gripping part is not included in the width) (hereinafter sometimes referred to as stretching ratio) , It is preferably 0.70 to 1.10, more preferably 0.8 to 1.05, and still more preferably 0.80 to 1.00.

Gripping of the film is performed, for example, by using a plurality of clips.

The plurality of clips can be fixed to an endless chain of a predetermined length, depending on the size of the conveying device, the chain moves at the same speed as the film, and the clip is installed in the appropriate position of the chain, and enters the dryer The transparent resin film was gripped before, and the gripping was released at the time of exiting the dryer.

In a plurality of clips provided on one end of the film, the space between the adjacent clips is, for example, 1 to 50 mm, preferably 3 to 25 mm, more preferably 5 to 10 mm. It is installed to be mm.

In addition, when the straight line orthogonal to the film conveying axis is aligned with the center of the grip portion of any clip at one end of the film, the intersection of the straight line with the other end of the film and the clip of the clip closest to the intersection point The distance in the center of the branch can be preferably 3 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less. When the distance is within the above range, it is easy to increase the homogeneity of the optical film, especially in the left and right.

When the ratio of the width of the film after heat treatment to the width of the film before heat treatment is in the above range, the film appearance tends to be good.

The amount of the solvent in the film after the heat treatment is preferably 0.001 to 3 mass%, more preferably 0.001 to 2 mass%, still more preferably 0.001 to 1.5 mass%, particularly preferably 0.001 based on the mass of the film. It is -1.3 mass%. When the amount of the solvent in the film after heat treatment is in the above range, the appearance of the optical film tends to be good.

When the heat treatment is over and the film comes out from the dryer, the gripping of the film is released, and the film end is preferably slit immediately. By performing a slit, the breakage which is likely to occur between the gripping portion and the non-gripping portion at the end of the film is removed from the film, thereby expanding the cracking of the film due to the conveyance of the film and a decrease in its temperature. It can be prevented in advance.

When the film leaves the dryer, the film may be quenched and shrunk, resulting in cracking. Therefore, it is preferable that there is a step of relaxing the film at a constant ratio from the dryer outlet to the position where the gripping of the film is released. The ratio is the width of the film coming out of the dryer (however, excluding the gripped width) (W) and the distance (F) at which the gripping part relaxes until the film is released from the dryer outlet, preferably 1.7≤F / W × 100 ≦ 6.9, more preferably 1.8 ≦ F / W × 100 ≦ 6.8, more preferably 1.9 ≦ F / W × 100 ≦ 6.7, even more preferably 2.0 ≦ F / W × 100 ≦ 6.7.

The distance at which one side is relaxed with respect to the conveyance direction of the film is referred to as Fa, and the distance at which the other end is relaxed is called Fb, and the sum of them is referred to as the distance F to be relaxed.

The distance from the dryer outlet until the gripping of the film is released is preferably 200 to 1,000 mm, more preferably 300 to 900 mm, and even more preferably 300 to 800 mm. When the distance is within the above range, the film is unlikely to be cracked, and there is a tendency that appearance defects such as sagging are less likely to occur.

Moreover, in the manufacturing method of this invention, from the viewpoint of being easy to manufacture the optical film which has the said characteristic, after peeling a coating film from a support body in process (b), heating the peeled coating film in process (c) , To manufacture the film. However, the optical film of the present invention may be a film produced by any production method as long as it has the characteristics relating to Y _mh and the like. For example, the film may be produced by post-baking the coating film before peeling the coating film from the support, and peeling the post-baking film from the support.

The manufacturing method of this invention may further include the process (d) of evaluating the film mentioned later after said process (a)-(c). In the step (d), the line profiles in the direction h and the direction v orthogonal to each other in the film inverse space obtained by Fourier transforming the projected image obtained by the projection method using the obtained film are the line profile h and the line profile v, respectively. And the line profiles in the direction h 'and the direction v' orthogonal to each other in the background inverse space obtained by Fourier transforming the background image obtained without using the film in the projection method, respectively, as the line profile h 'and the line profile v 'that is, from the line profile, h-line profile h' the frequency showing the maximum intensity for Y _mh is called, and the maximum intensity Y _mh of the line profile (h-h ') obtained by subtracting and said X _mh, line profile v The maximum intensity of the line profile (v-v ') obtained by subtracting the line profile v' from is Y _mv , and the frequency representing the maximum intensity Y _mv (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 value calculated from the values of Y _mh and Y _mv when the number is X _mv and Y _mh , Y _mv , X _mh and X _mv Based on, it is a process of evaluating a film.

In step (d), the homogeneity of the film, particularly optical homogeneity, can be evaluated based on the values of Y _mh and Y _mv and (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 . For example, by setting a predetermined value according to the required homogeneity, and comparing the result obtained with the film, the goodness of the film is judged, and the film is sorted to determine the Y _mh and Y _{mv values} . An optical film having excellent homogeneity in which the value and the value of (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 is equal to or less than a predetermined value can be produced. Moreover, while evaluating the said value, the drying conditions etc. can be adjusted, and the film of this invention which has the said characteristic can also be manufactured.

In the step (d) of evaluating the film, evaluating the homogeneity of the film based on the maximum strengths Y _mh and Y _mv measured by the evaluation method of the present invention, and judging whether the quality of the film is good or not It is preferable from the viewpoint of efficiently producing this excellent film. The criteria for determining the quality of a film may be appropriately set depending on the use of the produced film or the optical homogeneity required for the film, and is not particularly limited. When the quality of the film is judged for the purpose of obtaining a film having excellent homogeneity, which is suitably used in an optical film or the like, the film of the present invention is based on whether or not it has the properties described above. It is desirable to make a judgment of the good or bad.

According to the said evaluation process, it becomes possible to evaluate the homogeneity of a film, especially optical homogeneity, with higher precision compared with a conventional evaluation method. Specifically, according to the evaluation step, optical properties and / or physical properties caused by unevenness in both directions in the TD direction and MD direction or unevenness in the width of the width, etc., which could not be evaluated with sufficient precision by the conventional evaluation method, etc. It is possible to evaluate the non-uniformity of properties, and it is possible to accurately evaluate the homogeneity of the film regardless of the kind of non-uniformity. Moreover, it is also possible to quantify the homogeneity of a film by the said evaluation process. The evaluation step in step (d), specifically, the following steps (1) to (5):

(1) A step of obtaining a projected image by a projection method in which light from a light source is irradiated onto a film and the light transmitted through the film is projected onto a projection surface,

(2) A process of obtaining a background image by projecting light from a light source onto a projection surface without using a film in the projection method of step (1),

(3) The projection image obtained in step (1) and the background image obtained in step (2) are numerically quantified by gray-scale, respectively, and Fourier transform the digitized image data to inverse space (film inverse space and background inverse space) Phase),

(4) A step of obtaining a blank corrected line profile by subtracting each line profile in the two directions orthogonal in the inverse space of the background image from each line profile in two directions orthogonal in the inverse space on the projected image. ,

And,

(5) Process for measuring the maximum intensity (Y _mh and Y _mv ) of the blank corrected line profile obtained in step (4)

It includes at least.

In step (1), light from a light source is irradiated onto the film, and light transmitted through the film is projected onto a projection surface to obtain a projected image. In step (1), for example, as shown in FIG. 1, a film, a projection surface, or the like may be arranged. Specifically, the light source 1, the film 2, and the projection surface 3 are arranged, and the projection image 4 projected on the projection surface 3 is photographed with the camera 6 to obtain a projection image. The light 5 output from the light source 1 passes through the film 2 and the transmitted light is projected onto the projection surface 3 as a projected image 4. When the light 5 passes through the film 2, if the film 2 is homogeneous, the light 5 passes through the film 2 homogeneously to reach the projection surface 3, but the film 2 is homogeneous When the light 5 is transmitted through the film 2, reflection and / or refraction occurs, and there is a distorted state compared with the state output from the light source. The light of reaches the projection surface 3. By evaluating the thus-obtained projected image 4 by the method described later, the optical homogeneity of the film can be evaluated or quantified with high precision. From the viewpoint of easy to obtain a clear projected image, it is preferable to take a picture in a dark room by transmitting only light from a light source through the film. The type of the light source is not particularly limited, and for example, an LED light source or a halogen lamp may be used. A light source close to the point light source is preferable, and the light emitting portion is preferably 1 cm or less in diameter. Since the projected image tends to become opaque when passing through a filter or a lens, light that does not pass through the filter or lens is preferable. The projection surface is not particularly limited as long as the projected image of the film is viewed, but for example, an acrylic plate, a vinyl chloride plate, a polyethylene plate, a movie screen, or the like may be used. The photographing method of the image projected on the projection surface is not particularly limited, for example, as shown in Fig. 1, the projection surface 3, the film 2, and the light source 1 are arranged in a straight line, and the projection surface 3 The camera 6 may be fixed at a position where the projected image 4 projected on the camera is photographed obliquely. The photographing mode may be appropriately set, or, for example, a setting as described in the examples may be used. In this way, a projected image is obtained.

In step (2), in the projection method of step (1), a film is not used, and light from a light source is projected onto a projection surface to obtain a projected image. Specifically, for example, in FIG. 1, photographing is performed with only the film 2 removed, and a background image is obtained.

In the step (3), the projected image obtained in the step (1) and the background image obtained in the step (2) are respectively digitized by gray scale, and Fourier transform of the digitized image data is obtained to obtain an inverse spatial image. Gray scale can be performed, for example, by 8-bit gray scale using image analysis software (for example, "National Hygiene Research Institute" "Image-J"). The projection image and the background image can be digitized by gray scale. Next, the inverse spatial image (film inverse spatial image and background inverse spatial image) is obtained by Fourier transform of the digitized image data. By performing Fourier transform of the digitized image data, it is possible to obtain the period and amplitude of the lightness of the image. As a method of Fourier transform, the Fourier transform function of image analysis software (Image-J) is used, for example.

In the step (4), blank corrected lines are subtracted from each line profile in the two directions orthogonal in the inverse space of the projected image, and each line profile in the two directions orthogonal in the inverse space on the background image is subtracted, respectively. Get a profile.

In step (5), the maximum intensity Y _max (Y _mh and Y _mv respectively) of the blank corrected line profile obtained in step (4) is measured. The measurement methods of Y _mh and Y _mv are as described above for the film of the present invention, and, for example, each of the horizontal direction (h1 direction) and the vertical direction (v1 direction) passing through the center of the inverse space. When a line profile is created with respect to the direction, it is represented as a graph showing frequency on the X axis and intensity on the Y axis, for example, as shown in FIG. 3. Then, the maximum intensity Y _max in the horizontal (h1 direction) line profile is referred to as Y _mh1 , and X is a value obtained by subtracting the median value X _cen of the entire frequency in the blank-corrected line profile from the frequency representing the maximum intensity Y _mh1 . _{Let max} be X _mh1 . Moreover, the maximum intensity Y _max in the line profile in the vertical direction (v1 direction) is Y _mv1 , and X is a value obtained by subtracting the median value X _cen of the total frequency in the blank-corrected line profile from the frequency representing the maximum intensity Y _mv1 . _{Let max} be X _mv1 . Further, the two directions are not particularly limited as long as they are orthogonal to each other, and may be two directions that do not pass through the center, and may not be horizontal and vertical directions.

By measuring the Y _mh and Y _mv , it is possible to evaluate the homogeneity in the two-dimensional direction of the film. One of the causes of deterioration in the optical homogeneity of the film is a non-uniformity of the kind that cannot be sufficiently detected by one-dimensional evaluation, such as, for example, unevenness of stripes. According to the evaluation method of the present invention, since the optical homogeneity can be evaluated in the two-dimensional direction, evaluation can be performed with high precision regardless of the kind of non-uniformity of the film. In addition, it is also possible to quantify the homogeneity of the film by measuring Y _mh and Y _mv to obtain a value.

Further, in addition to the maximum intensity Y _mh and Y _mv , evaluation is performed using X _mh and X _mv , which is the value obtained by subtracting the median value X _cen of the total frequency from the blank-corrected line profile from the frequencies representing these maximum intensity. , It is also possible to detect a cycle in which surface unevenness, which is one cause affecting the optical homogeneity of the film, is generated.

In addition, when the optical film of the present invention has a multi-layer structure, the production method of the present invention includes at least one functional layer or the like in the film obtained in step (c) between steps (c) and (d). The step of laminating may be included, and after the step (d), a step of laminating at least one functional layer or the like to the film may be included.

<Layer composition>

The optical film of the present invention and the optical film produced by the production method of the present invention include polyimide resins and / or polyamide resins having a weight average molecular weight of 230,000 or more, and fillers having an average primary particle diameter of 5 to 35 nm. As long as it contains, it may be a single layer or a multilayer stack. Moreover, when the optical film of this invention is a multilayer laminated body, the said laminated body has at least one layer containing both the said resin and a filler. In the optical film of the present invention, the values of Y _mh and Y _mv , and (Y _mh + Y _mv ) / (X _mh + X _mv ) ^{1/2 in} the monolayer state, which is a layer containing both the resin and the filler, are the above It may be within a predetermined range, in the state of a laminate having a multi-layered structure in which at least one layer including both the resin and the filler is laminated, and at least one functional layer or the like is laminated on the layer, Y _mh and The value of Y _{mv and} the value of (Y _mh + Y _mv ) / (X _mh + X _mv ) ^1/2 may be within the above-described predetermined range. In the following, the optical film of the present invention having a multi-layer structure in which other layers such as at least one functional layer are laminated on the optical film of the present invention is also referred to as an "optical laminate".

<Optical laminate>

The optical film of the present invention may be an optical laminate having a multilayer structure having at least one layer including both the resin and the filler, and at least one functional layer laminated on at least one surface of the layer. Examples of the functional layer include an ultraviolet absorbing layer, a hard coating layer, an adhesive layer, a color adjusting layer, a refractive index adjusting layer, a primer layer, and a gas barrier layer. The functional layer can be used alone or in combination of two or more. Moreover, when measuring various physical properties, it is preferable to measure with the optical film of this invention alone (in a single layer state) rather than an optical laminated body.

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

The adhesive layer is a layer having an adhesive function and has a function of adhering an optical film to other members. As a material for forming the adhesive layer, a commonly known one 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 adhesive layer may be a layer adhered to an object by pressing, called a pressure sensitive adhesive (PSA). The pressure-sensitive adhesive may be a pressure sensitive adhesive that is `` substance having tackiness at room temperature and adheres to an adherend at light pressure '' (JIS K6800), and `` appropriate means for containing a specific component in a protective film (microcapsule) '' It may be a capsule adhesive, which is an adhesive capable of maintaining stability until the film is destroyed by (pressure, heat, etc.) (JIS K6800).

The color adjustment layer is a layer having a function of color adjustment, and is a layer that can be adjusted to the color targeting the optical laminate. The color adjustment layer is, for example, a layer containing a resin and a colorant. Examples of the colorant include inorganic pigments such as titanium oxide, zinc oxide, bengala, titanium oxide-based fired pigments, ultramarine, cobalt aluminate, and carbon black; Organic pigments such as azo-based compounds, quinacridone-based compounds, anthraquinone-based compounds, perylene-based compounds, isoindolinone-based compounds, phthalocyanine-based compounds, quinophthalone-based compounds, styrene-based compounds, and diketopyrrolopyrrole-based compounds; Extender pigments such as barium sulfate and calcium carbonate; And dyes such as basic dyes, acid dyes, and mordant dyes.

The refractive index adjusting layer is a layer having a function of adjusting the refractive index, and is, for example, a layer having a different refractive index from a layer containing both the resin and the filler, and capable of imparting a predetermined refractive index to the optical laminate. The refractive index adjusting layer may be, for example, an appropriately selected resin, and optionally a resin layer containing a pigment, or a thin metal film. Examples of the pigment for adjusting the refractive index include silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide and tantalum oxide. The average primary particle size of the pigment may be 0.1 µm or less. By setting the average primary particle size of the pigment to 0.1 µm or less, diffuse reflection of light passing through the refractive index adjusting layer can be prevented and a decrease in transparency can be prevented. Examples of the metal used in the refractive index adjusting layer include metal oxides 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, or And metal nitrides.

In one preferred embodiment of the present invention, the optical film has a hard coating layer on at least one side (one side or both sides) of the layer containing the resin and the filler. When a hard coating layer is provided on both surfaces, the components contained in the two hard coating layers may be the same or different from each other.

Examples of the hard coating layer include known hard coating layers such as acrylic, epoxy, urethane, benzyl chloride, and vinyl. Among these, a hard coating layer of an acrylic type, a urethane type, or a combination thereof can be preferably used from the viewpoint of suppressing a decrease in visibility in the wide-angle direction of the optical film and improving the bending resistance. The hard coat layer is preferably a cured product of a curable composition containing a curable compound, and is formed by polymerizing the curable compound by irradiation with active energy rays. As a curable compound, a polyfunctional (meth) acrylate type compound is mentioned, for example. A polyfunctional (meth) acrylate-based compound is a compound having at least two (meth) acryloyl groups in a molecule.

Examples of the polyfunctional (meth) acrylate-based compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1,6-hexanedioldi (meth) acrylate, and neopentyl glycoldi (Meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaglycerol Tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerin tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) Acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tris ((meth) acryloyloxyethyl) Isocyanurate; A phosphazene-based (meth) acrylate compound in which a (meth) acryloyl group is introduced into the phosphazene ring of the phosphazene compound; Urethane (meth) acrylate compounds obtained by reaction of a polyisocyanate having at least two isocyanato groups in a molecule and a polyol compound having at least one (meth) acryloyl group and a hydroxyl group; A polyester (meth) acrylate compound obtained by reaction of at least two carboxylic acid halides in a molecule and a polyol compound having at least one (meth) acryloyl group and a hydroxyl group; And oligomers such as dimers and trimers of each compound. These compounds are used individually or in mixture of 2 or more types.

The curable compound may include a monofunctional (meth) acrylate-based compound in addition to the polyfunctional (meth) acrylate-based compound described above. Examples of the monofunctional (meth) acrylate-based compound include hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) ) Acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycidyl (meth) acrylate, and the like. These compounds are used alone or in combination of two or more. The content of the monofunctional (meth) acrylate-based compound is preferably 10% by mass or less when the solid content of the compound contained in the curable composition is 100% by mass. In addition, in this specification, solid content means all the components except the solvent contained in a curable composition.

Moreover, the curable compound may contain a polymerizable oligomer. The hardness of the hard coat layer can be adjusted by containing a polymerizable oligomer. As the polymerizable oligomer, terminal (meth) acrylate polymethyl methacrylate, terminal styryl poly (meth) acrylate, terminal (meth) acrylate polystyrene, terminal (meth) acrylate polyethylene glycol, terminal (meth) acrylate acrylic And macromonomers such as a nitrile-styrene copolymer and a terminal (meth) acrylate styrene-methyl (meth) acrylate copolymer. The content of the polymerizable oligomer is preferably 5 to 50 mass% when the solid content of the compound contained in the curable composition is 100 mass%.

The curable composition forming the hard coating layer may contain an additive in addition to the polyfunctional (meth) acrylate-based compound and the polymerizable oligomer. As an additive, a polymerization initiator, a silica, a leveling agent, a solvent, etc. are mentioned, for example. As a solvent, methyl ethyl ketone, polypropylene glycol monomethyl ether, etc. are mentioned, for example.

The film thickness of the hard coat layer is preferably 3 to 30 µm, more preferably 5 to 25 µm, and still more preferably 5 to 20 µm, from the viewpoint of improving the hardness, bending resistance and visibility of the optical film.

<Protective film>

A protective film may be laminated on the optical film of the present invention. The protective film may be laminated on one side or both sides of the optical film. When the optical film of the present invention has a functional layer on one side of a layer containing both the resin and the filler, the protective film is laminated on the surface of the layer side or the functional layer side containing both the resin and the filler. It may be, or may be laminated on both surfaces. When the optical film has a functional layer on both sides of the layer containing both the resin and the filler, the protective film may be laminated on the surface of the functional layer side of one side, or on the surface of both functional layer sides. It may be laminated. The protective film is a film for temporarily protecting the surface of the optical film or functional layer, and is not particularly limited as long as it is a peelable film capable of protecting the surface of the optical film or functional layer. Examples of the protective film include polyester-based resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; And polyolefin-based resin films such as polyethylene and polypropylene films, and acrylic-based resin films, and are preferably selected from the group consisting of polyolefin-based resin films, polyethylene terephthalate-based resin films, and acrylic-based resin films. When two protective films are laminated on the optical film of the present invention, each protective film may be the same or different.

The thickness of the protective film is not particularly limited, but is usually 10 to 120 μm, preferably 15 to 110 μm, and more preferably 20 to 100 μm. When two protective films are laminated on the optical film of the present invention, the thickness of each protective film may be the same or different.

<Flexible display device>

The present invention also provides a flexible display device comprising the optical film. The optical film of the present invention is preferably used as a front plate in a flexible display device, and the front plate may be called a window film. The flexible display device is composed of a laminate for a flexible display device and an organic EL display panel, and a laminate for a flexible display device is disposed on the viewer side with respect to the organic EL display panel, and is configured to be bendable. . As a laminated body for a flexible display device, a polarizing plate, preferably a circular polarizing plate, and a touch sensor may be further included, and the lamination order is arbitrary, but a window film, a polarizing plate, a touch sensor or a window film, a touch sensor from the viewer side, It is preferable that they are laminated in the order of the polarizing plates. When the polarizing plate is present on the viewing side than the touch sensor, it is preferable because the pattern of the touch sensor is difficult to visualize and the visibility of the display image is improved. Each member can be laminated using an adhesive, an adhesive, or the like. In addition, a light blocking pattern formed on at least one surface of any one of the window film, the polarizing plate, and the touch sensor may be provided.

<Circular polarizer>

As described above, the flexible display device of the present invention is preferably provided with a polarizing plate, particularly a circular polarizing plate. The circular polarizing plate is a functional layer having a function of transmitting only the right or left circularly polarizing component by laminating a λ / 4 phase difference plate on the linearly polarizing plate. For example, by converting external light into right circularly polarized light, it is reflected by the organic EL panel, blocks external light that is left circularly polarized, and transmits only the light emitting component of the organic EL to suppress the influence of reflected light and make it easier to see images. do. In order to achieve the circular polarization function, the absorption axis of the linear polarizing plate and the ground axis of the λ / 4 retardation plate need to be theoretically 45 °, but practically 45 ± 10 °. The linear polarizing plate and the λ / 4 retardation plate do not necessarily need to be stacked adjacent to each other, and the relationship between the absorption axis and the slow axis should just satisfy the above range. It is desirable to achieve full circular polarization at all wavelengths, but in practical use, the circular polarizing plate in the present invention also includes an elliptical polarizing plate. It is also preferable to further improve the visibility in the state of wearing polarized sunglasses by laminating a lambda / 4 phase difference film on the viewing side of the linear polarizing plate and making the emitted light circularly polarized.

The linearly polarizing plate is a functional layer having a function of passing through light oscillating in the direction of the transmission axis, but blocking polarization of a vibration component perpendicular to it. The linear polarizer may be configured with a linear polarizer alone or a linear polarizer and a protective film affixed to at least one surface thereof. The linear polarizing plate may have a thickness of 200 µm or less, and preferably 0.5 to 100 µm. When the thickness of the linear polarizing plate is within the above range, the flexibility of the linear polarizing plate tends to be difficult to deteriorate.

The linear polarizer may be a film-type polarizer produced by dyeing and stretching a polyvinyl alcohol (hereinafter sometimes simply referred to as PVA) -based film. A dichroic dye such as iodine is adsorbed to a PVA-based film oriented by stretching, or stretched in a state adsorbed to PVA to orient the dichroic dye to exhibit polarization performance. In the production of the above-mentioned film type polarizer, other steps may be included such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying. The stretching or dyeing process may be performed alone with a PVA-based film, or may be performed in a state in which it is laminated with other films such as polyethylene terephthalate. The film thickness of the PVA-based film used is preferably 10 to 100 µm, and the draw ratio is preferably 2 to 10 times.

Moreover, as another example of the said polarizer, the liquid crystal coating type polarizer formed by apply | coating a liquid crystal polarizing composition is mentioned. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. It is preferable that the liquid crystal compound has properties that exhibit a liquid crystal state, and particularly, a high degree of alignment such as a smectic phase can exhibit high polarization performance. Moreover, it is preferable that a liquid crystalline compound has a polymerizable functional group.

The dichroic dye compound may be aligned with the liquid crystal compound to exhibit dichroism, and may have a polymerizable functional group, or the dichroic dye itself may have liquid crystallinity.

Any of the compounds included in the liquid crystal polarizing composition has a polymerizable functional group. The liquid crystal polarizing composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, and a silane coupling agent.

The liquid crystal polarizing layer is produced 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 to have a thinner thickness than the film-type polarizer, and the thickness is preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

The alignment film is produced, for example, by applying an alignment film forming composition on a substrate and imparting alignment properties by rubbing, polarization irradiation, or the like. The alignment film forming composition may include an alignment agent, and may further include a solvent, a crosslinking agent, an initiator, a dispersing agent, a leveling agent, a silane coupling agent, and the like. Examples of the alignment agent include polyvinyl alcohols, polyacrylates, polyamic acids, and polyimides. When using the alignment agent which provides orientation by polarization irradiation, it is preferable to use the alignment agent containing a cinnamate group. The weight average molecular weight of the polymer used as the alignment agent is, for example, about 10,000 to 1,000,000. The film thickness of the alignment film is preferably 5 to 10,000 nm, and more preferably 10 to 500 nm in that the orientation regulating force is sufficiently expressed.

The liquid crystal polarizing layer may be peeled off from the substrate and transferred and laminated, or the substrate may be laminated as it is. It is also preferable that the substrate serves as a transparent substrate for the protective film, retardation plate, and window film.

As the protective film, a transparent polymer film may be used, and the same material or additive used for the transparent substrate of the window film can be used. Moreover, the coating type protective film obtained by apply | coating and curing a cationic curing composition, such as an epoxy resin, or a radical curing composition, such as an acrylate, may be sufficient. The protective film may contain a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like, if necessary. . The thickness of the protective film is preferably 200 µm or less, and more preferably 1 to 100 µm. When the thickness of the protective film is within the above range, the flexibility of the film tends to be difficult to deteriorate.

The lambda / 4 phase difference plate is a film that gives a lambda / 4 phase difference in a direction orthogonal to the traveling direction of incident light (in-plane direction of the film). The λ / 4 retardation plate may be a stretched retardation plate produced by stretching a polymer film such as a cellulose-based film, an olefin-based film, or a polycarbonate-based film. The λ / 4 retardation plate, if necessary, retardation adjuster, plasticizer, ultraviolet absorber, infrared absorber, colorant such as pigment or dye, fluorescent whitening agent, dispersant, heat stabilizer, light stabilizer, antistatic agent, antioxidant, lubricant, solvent Etc. may be included.

The thickness of the stretched retardation plate is preferably 200 μm or less, and more preferably 1 to 100 μm. When the thickness of the stretched retardation plate is within the above range, the flexibility of the stretched retardation plate tends to be less likely to decrease.

Moreover, as another example of the lambda / 4 phase difference plate, a liquid crystal coating type retardation plate formed by applying a liquid crystal composition is mentioned.

The liquid crystal composition includes a liquid crystal compound exhibiting liquid crystal states such as nematic, cholesteric, and smectic. The liquid crystal compound has a polymerizable functional group.

The liquid crystal composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, and a silane coupling agent.

The liquid crystal coating-type retardation plate can be produced by coating and curing a liquid crystal composition on a base, as in the liquid crystal polarizing layer, to form a liquid crystal retardation layer. The liquid crystal-coated retardation plate can be formed to have a thinner thickness than the stretched retardation plate. The thickness of the liquid crystal polarizing layer is preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

The liquid crystal coating type retardation plate may be peeled off from the substrate and transferred to be laminated, or the substrate may be laminated as it is. It is also preferable that the substrate serves as a transparent substrate for the protective film, retardation plate, and window film.

In general, the shorter the wavelength, the greater the birefringence and the longer the wavelength, the more materials exhibiting the smaller birefringence. In this case, since a phase difference of λ / 4 cannot be achieved in the entire visible light region, the in-plane phase difference is preferably 100 to 180 nm, so that it is λ / 4 with respect to the vicinity of 560 nm with high visibility. It is preferably designed to be 130 to 150 nm. The reverse dispersion λ / 4 retardation plate using a material having a birefringence wavelength dispersion characteristic as opposed to normal is preferable in view of good visibility. As such a material, for example, a stretched retardation plate described in JP 2007-232873 A and the like and a liquid crystal coated retardation plate described in JP 2010-30979 A can be used.

As another method, a technique of obtaining a broadband λ / 4 phase difference plate by combining with a λ / 2 phase difference plate is also known (for example, Japanese Patent Application Laid-open No. Hei 10-90521, etc.). The λ / 2 retardation plate is also made of the same material and method as the λ / 4 retardation plate. The combination of the stretched retardation plate and the liquid crystal coating retardation plate is arbitrary, but any of them can reduce the film thickness by using the liquid crystal coating retardation plate.

In order to increase visibility in an oblique direction, a method of laminating a positive C plate is known to the original polarizing plate (for example, Japanese Patent Application Laid-open No. 2014-224837, etc.). The definition C plate may be a liquid crystal coating type retardation plate or a stretched retardation plate. The phase difference in the thickness direction of the phase difference plate is preferably -200 to -20 nm, more preferably -140 to -40 nm.

<Touch sensor>

It is preferable that the flexible display device of the present invention has a touch sensor as described above. The touch sensor is used as an input means. As a touch sensor, various forms, such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitive method, are mentioned, Preferably, a capacitive method is mentioned.

The capacitive touch sensor is divided into an active area and an inactive area located on an outer portion of the active area. The active area is an area corresponding to an area (display area) where a screen is displayed on the display panel, and an area where a user's touch is detected, and an inactive area is an area corresponding to an area (non-display area) where a screen is not displayed on the display device. . The touch sensor includes a substrate having flexible characteristics, a sensing pattern formed in an active region of the substrate, and a sensing pattern formed in an inactive region of the substrate and connected to an external driving circuit through the sensing pattern and the pad portion. It can contain. As the substrate having flexible properties, the same material as the transparent substrate of the window film can be used.

The sensing pattern may include a first pattern formed in the first direction and a second pattern formed in the second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed on the same layer, and in order to sense a touched point, each pattern must be electrically connected. The first pattern is a form in which a plurality of unit patterns are connected to each other via a seam, but the second pattern is a structure in which a plurality of unit patterns are separated from each other in an island form, and thus, to electrically connect the second pattern, separate Bridge electrodes are required. A well-known transparent electrode can be applied to the electrode for connection of the 2nd pattern. As a material of the transparent electrode, 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-ethylenedioxythiophene)), carbon nanotubes (CNT), graphene, metal wires, and the like, and preferably ITO. These may be used alone or in combination of two or more. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, and chromium. These may be used alone or in combination of two or more. .

The bridge electrode may be formed on the insulating layer with an insulating layer over the sensing pattern, a bridge electrode may be formed on the substrate, and an insulating layer and a sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, or may be formed of molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of them.

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 seam of the first pattern and the bridge electrode, or may be formed as a layer covering the entire sensing pattern. In the case of the layer covering the entire sensing pattern, the bridge electrode may connect the second pattern through the contact hole formed in the insulating layer.

The touch sensor has a difference in transmittance between a pattern area where a sensing pattern is formed and a non-pattern area where no sensing pattern is formed, specifically, a difference in light transmittance caused by a difference in refractive index in these areas. As a means for properly compensating, an optical control layer may be further included between the substrate and the electrode. The optical control layer may include an inorganic insulating material or an organic insulating material. The optical control layer may be formed by coating a photocurable composition comprising a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The refractive index of the optical control layer can be increased by the inorganic particles.

The photocurable organic binder may include a copolymer of each monomer, such as an acrylate-based monomer, a styrene-based monomer, and a carboxylic acid-based monomer, within a range that does not impair the effects of the present invention. The photocurable organic binder may be, for example, a copolymer containing 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 include each additive such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

<Adhesive layer>

Each layer (window film, circular polarizing plate, touch sensor) forming the laminate for the flexible image display device and the film member (linear polarizing plate, λ / 4 retardation plate, etc.) constituting each layer can be bonded by an adhesive. . Examples of the adhesive include water-based adhesives, organic solvent-based, solvent-free adhesives, solid adhesives, solvent volatilization-type adhesives, moisture-curable adhesives, heat-curable adhesives, anaerobic curing, active energy ray-curable adhesives, curing agent mixed adhesives, heat-melting adhesives, and pressure-sensitive adhesives Adhesives (adhesives), rewet type adhesives, and other commonly used adhesives can be used, and preferably an aqueous solvent volatilization type adhesive, active energy ray-curable adhesive, or adhesive can be used. The thickness of the adhesive layer can be appropriately adjusted depending on the required adhesive strength, etc., preferably 0.01 to 500 µm, more preferably 0.1 to 300 µm. Although a plurality of adhesive layers exist in the laminate for the flexible image display device, the thickness and type of each may be the same or different.

As the aqueous solvent-based adhesive, a water-dispersible polymer such as a polyvinyl alcohol-based polymer, a water-soluble polymer such as starch, an ethylene-vinyl acetate-based emulsion, or a styrene-butadiene-based emulsion can be used as the main polymer. In addition to the main polymer and water, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, etc. may be blended. In the case of bonding with the water-based solvent volatilization-type adhesive, the water-based solvent volatilization-type adhesive is injected between the adhered layers to bond the adhered layers, followed by drying to impart adhesion. When using the above-mentioned water-based solvent-based adhesive, the thickness of the adhesive layer is preferably 0.01 to 10 μm, more preferably 0.1 to 1 μm. When the above-mentioned water-based solvent volatilization type adhesive is used for a plurality of layers, the thickness or type of each layer may be the same or different.

The active energy ray-curable adhesive may be formed by curing an active energy ray-curing composition containing a reactive material that irradiates active energy rays to form an adhesive layer. The active energy ray-curable composition may contain at least one polymerizable product of a radically polymerizable compound and a cationic polymerizable compound similar to those contained in the hard coating composition. As the radically polymerizable compound, the same compound as the radically polymerizable compound in the hard coating composition can be used.

As the cationic polymerizable compound, the same compound as the cationic polymerizable compound in the hard coating composition can be used.

As the cationically polymerizable compound used in the active energy ray curing composition, an epoxy compound is particularly preferred. It is also preferable to include a monofunctional compound as a reactive diluent in order to lower the viscosity as an adhesive composition.

The active energy ray curing composition may contain a monofunctional compound in order to lower the viscosity. As the monofunctional compound, an acrylate-based monomer having one (meth) acryloyl group in one molecule or a compound having one epoxy group or oxetanyl group in one molecule, for example, glycidyl (meth) And acrylates.

The active energy ray curing composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, and these are suitably 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 cation polymerization. Among the substrates of the hard coating composition, an initiator capable of initiating at least either radical polymerization or cationic polymerization by active energy ray irradiation may be used.

The active energy ray curing composition may further include an ion trapping agent, an antioxidant, a chain transfer agent, an adhesion agent, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, an antifoaming agent, an additive, and a solvent. When the two adhesive layers are adhered by the active energy ray-curable adhesive, the active energy ray-curable composition is applied to one or both of the adhesive layers, and then bonded, and active to either of the adhesive layers or both adhesive layers It can bond by irradiating an energy ray and hardening. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm. When the active energy ray-curable adhesive is used for forming a plurality of adhesive layers, the thickness or type of each layer may be the same or different.

As the above-mentioned pressure-sensitive adhesive, depending on the main polymer, any of those classified into acrylic pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, rubber-based pressure-sensitive adhesive, and silicone-based pressure-sensitive adhesive may be used. In addition to the main polymer, a crosslinking agent, a silane-based compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, etc. may be added to the pressure-sensitive adhesive. The adhesive layer is formed by dissolving and dispersing each component constituting the pressure-sensitive adhesive in a solvent to obtain a pressure-sensitive adhesive composition, and then drying the coating after applying the pressure-sensitive adhesive composition on a substrate. The adhesive layer may be formed directly, or may be transferred to one formed on a separate substrate. It is also preferable to use a release film to cover the adhesive surface before adhesion. When using the active energy ray-curable adhesive, the thickness of the adhesive layer is preferably 0.1 to 500 µm, more preferably 1 to 300 µm. When using multiple layers of the said adhesive, the thickness and kind of each layer may be same or different.

<Shading pattern>

The light-shielding pattern can be applied as at least a part of the bezel or housing of the flexible image display device. The visibility of the image is improved by shielding the wiring arranged in the edge portion of the flexible image display device by the light-shielding pattern, making it difficult to visually recognize it. The light shielding pattern may be in the form of a single layer or multiple layers. The color of the light-shielding pattern is not particularly limited, and various colors such as black, white, and metal may be used. The light-shielding pattern may be formed of a pigment for realizing color, and a polymer such as acrylic resin, ester resin, epoxy resin, polyurethane, and silicone. It may be used alone or as 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 preferably 1 to 100 μm, more preferably 2 to 50 μm. Moreover, it is also preferable to give a shape, such as a slope, in the thickness direction of a light-shielding pattern.

[Example]

 Hereinafter, the present invention will be described in more detail by examples. In the examples, "%" and "part" mean mass% and parts by mass unless otherwise specified. First, a method of measuring a property value will be described.

<Weight average molecular weight>

Gel permeation chromatography (GPC) measurements

(1) Pretreatment method

The sample was dissolved in γ-butyrolactone (GBL) to make a 20% by mass solution, diluted 100-fold with DMF eluent, and filtered with a 0.45 μm membrane filter as a measurement solution.

(2) Measurement conditions

Column: TSKgel SuperAWM-H × 2 + SuperAW2500 × 1 (6.0 mm I.D. × 150 mm × 3)

Eluent: DMF (10 mM lithium bromide added)

Flow rate: 0.6 mL / min.

Detector: RI detector

Column temperature: 40 ℃

Injection volume: 20 μL

Molecular weight standard: standard polystyrene

<Imidation rate>

The imidation ratio was determined as follows by ¹ H-NMR measurement.

(1) Pretreatment method

The sample was dissolved in deuterated dimethyl sulfoxide (DMSO-d ₆ ) to prepare a 2% by mass solution as a measurement solution.

(2) Measurement conditions

Measuring device: JEOL 400 MHz NMR device JNM-ECZ400S / L1

Standard: DMSO-d ₆ (2.5 ppm)

Sample temperature: room temperature

Integration times: 256 times

Relax time: 5 seconds

(3) Analysis method of imidation rate

In the obtained ¹ H-NMR spectrum, the benzene proton was observed at 7.0 to 9.0 ppm, and among them, the integral ratio of benzene proton A derived from a structure that does not change before and after imidization is called Int _A. Further, the amide proton having an amic acid structure remaining in the polyimide was observed at 10.5 to 11.5 ppm, and this integral ratio was referred to as Int _B. The imidation ratio was calculated | required by the following formula from these integral ratios.

In the above formula, α is the number ratio of benzene proton A to 1 amide proton in the case of polyamic acid (0% imidation).

<Average primary particle diameter>

The specific surface area of the powder dried by drying the silica sol at 300 ° C was measured using a monosurface MS-16 manufactured by Yuasa Ionics, and the measured specific surface area S (m2 / g) was used. The average primary particle size was calculated by the formula D (nm) = 2720 / S.

<Viscosity of varnish>

It measured according to JIS K8803: 2011 using Brookfield's E-type viscosity meter DV-II + Pro. The measurement temperature was 25 ° C.

<Film thickness and film thickness distribution of the support>

Using ID-C112XBS manufactured by Mitsutoyo Co., Ltd., the film thickness of 20 points or more was measured in the width direction of the support, and the difference between the average value and each data was calculated to obtain a film thickness distribution.

<Film thickness>

The film thickness of 10 or more points was measured using ID-C112XBS manufactured by Mitsutoyo Co., Ltd., and the average value was calculated.

<Total light transmittance of film>

The total light transmittance of the film was measured in accordance with JIS K7105: 1981, by a fully automatic direct read haze computer HGM-2DP manufactured by Suga Tester Co., Ltd.

<Yellowness of the film>

The yellowness (Yellow Index: YI value) of the optical film was measured using an ultraviolet visible near-infrared spectrophotometer "V-670" manufactured by Nippon Spectroscopic Co., Ltd. After background measurement in the absence of a sample, the optical film is set in a sample holder, the transmittance of 300-800 nm is measured, the tristimulus values (X, Y, Z) are determined, and the following formula is used. The YI value was calculated.

YI = 100 × (1.2769X-1.0592Z) / Y

<Flexibility of film>

In accordance with JIS P8115, the number of times until fracture was measured using a D-type MIT internal fatigue tester (Toyo Seiki Co., Ltd.). The radius of curvature R was measured to 1.

<Tear strength of film>

The tear strength of the film was measured according to the Trouser Test Method under the following conditions according to JIS K 7128-1. The strength obtained by dividing the strength obtained by setting the tear direction to the MD direction by the length of the sample was referred to as tear strength E _MD (N / mm). The tearing direction was set to the TD direction, and the strength obtained in the same manner was referred to as E _TD (N / mm). In addition, the strength obtained by dividing the strength obtained by setting the tear direction to the MD direction by the cross-sectional area of the sample was referred to as tear strength F _MD (N / mm 2). The tearing direction was set to the TD direction, and the strength obtained in the same manner was referred to as F _TD (N / mm 2).

(Measuring conditions)

Sample dimensions: L 150 mm × W 50 mm, center slit 75 mm

Test conditions: test speed; 200 mm / min

           Number of measurements; n = 5

Test environment: 25 ℃ ± 2 ℃, 50% RH ± 10% RH

Measuring device: Universal testing machine 5982 (manufactured by Instron)

<Tensile modulus of film>

The film was cut into a dumbbell shape of 100 mm × 10 mm, and subjected to tensile testing at a test speed of 5 m / min and a load cell of 5 kN using an electromechanical universal testing machine (manufactured by Instron) in accordance with JIS K7127. , The tensile modulus of the optical film was measured.

<Evaluation method of optical homogeneity of film>

1. Shooting projected images and background images

In the dark room, as shown in Fig. 2, a light source 1, a film 2, a projection surface 3, and a camera 6 are arranged, and the projection image 4 is photographed. The distance between the light source 1 and the film 2 is 250 cm, the distance between the film 2 and the projection surface 3 is 30 cm, the film 2 and the projection surface 3 are arranged in parallel, and the camera 6 is It is installed just below the normal from the light source 1 to the screen, the distance between the camera 6 and the projection surface 3 (screen) is 30 cm, and the camera angle 7 (directs the camera to be perpendicular to the screen). From one state, the angle to incline upward) was 25 °. The background image was photographed in the same manner as the projection image photographed except that the film 2 was removed in FIG. 2. Details of the measurement conditions and shooting conditions are shown below.

Light source: LED light source ("LA-HDF15T" manufactured by Mori Watch Industry Co., Ltd.)

Film: The film produced in the following Examples and Comparative Examples was cut into 200 mm × 300 mm, and used as a measurement sample.

Projection surface: White commercial screen for watching movies (Theater House Co., Ltd., 「BTP600FHD-SH1000」)

Camera: Nikon Co., Ltd. `` COOLPIX (registered trademark) P600 ''

Detailed camera settings: Manual shooting mode

                    Image size 2M

                    Focus Manual focus (distance 0.3 m)

                    Shutter speed 1/2 second

                    Aperture value (F value) 4.2

                    Flash OFF

2. Fourier Transform

In this embodiment, since the camera is installed at the position of the camera angle, an inclination occurs in the projected image. Therefore, in order to correct the inclination of the projected image, the inclination correction conditions were first determined. In addition, correction is unnecessary when there is no distortion of the projected image.

(Determination of slope correction conditions)

A 10 cm × 10 cm square was drawn on a transparent film, and a reference projection image was taken under the condition 1 above. The obtained reference projection image was read with Adobe Systems' Photoshop (registered trademark) CS4, and the camera and screen were corrected to correspond to 90 ° using a distortion correction function of lens correction, and stored in a TIFF format. The conditions at this time were referred to as slope correction conditions. From the reference projected image after the tilt correction, the lengths for each of the vertical and horizontal pixels were calculated (vertical: 816 pixel = 10 cm, horizontal: 906 pixel = 10 cm).

(Fourier transform)

The projected images obtained as described above for the films of Examples and Comparative Examples were corrected under the inclination correction conditions determined as described above, and the corrected images were stored in TIFF format. The obtained projection image after tilt correction is image analysis software "Image-J, ver. 1.48 ”and converted to an 8-bit gray scale. In addition, the length of each vertical and horizontal pixel obtained from the reference projected image after tilt correction was used as a set scale. Among the gray scale images, a 10.2 cm × 11.2 cm (vertical × horizontal) rectangular range was selected, and an image of the selected range was Fourier transformed using Image-J to obtain an inverse spatial image. For the inverse spatial image after the Fourier transform, the correct value (horizontal direction: 1 pixel = 11.3 cm ^-1 , vertical direction: 1 pixel = 12.55 cm ^-1 ) was input to Set Scale.

3. Measurement of maximum intensity (Y _mh1 and Y _mv1 ) of blank corrected line profile

In the inverse space obtained as described above, a line profile was created for each of the horizontal direction (h1 direction) and the vertical direction (v1 direction) passing through the center of the inverse space. The line width was 10 pixels. The obtained line profile was preserved in text format. Next, the data in the text format is read into Excel (ver. 14.0) of Microsoft, and the line profile is standardized as follows, for each direction in the horizontal direction (h1 direction) and the vertical direction (v1 direction). , Y ", and the maximum intensity Y _max for each line profile is referred to as Y _mh1 and Y _mv1 , and the median value of the total frequency in the blank-corrected line profile from the frequencies representing maximum intensity Y _mh1 and Y _mv1 X _max , which is the value obtained by subtracting X _cen , is referred to as X _mh1 and X _mv 1. The standardization method will be described using the line profile in the horizontal direction (h1 direction) obtained in Example 1 as an example.

(Standardization method)

The frequency at which the value of Y becomes the maximum is called the center of X (X _cen ), and the value of Y at that time is called Y _cen . Next, centered on X _cen , the average value of Y is obtained for a region of 100 pixels in total for each 50 pixels at both ends, and the average value is referred to as a baseline (Y _base ). Then, the data Y is corrected according to the following equation so that Y _cen = 100 and Y _base = 0 to obtain Y '.

By performing the above correction on the line profile (data Y) obtained in Example 1 shown in Fig. 4, a line profile A (data Y ') as shown in Fig. 5 is obtained.

Next, the same operation was performed for the background image obtained in 1 to obtain a line profile of the background image. Specifically, a line profile B as shown in Fig. 6 was obtained.

Subsequently, from the profile A described above, the background profile B was subtracted by Excel to perform blank correction. In Example 1, data of line profile B as shown in FIG. 6 was subtracted from data Y 'of line profile A shown in FIG. 5 to obtain a blank corrected line profile A-B as shown in FIG. 7.

The line profile obtained in this way was smoothed to obtain a profile of Y "and was used to measure the maximum intensity of the line profile (Y _mh1 and Y _mv1 ). The smoothing of the graph was 21 data according to the following equation. The average value of y _i was calculated and performed.

(Sensory evaluation of visibility)

In an indoor environment dimmed with 50 to 100 lux, the produced film was visually inspected from an angle of 80 ° at an elevation angle, and visibility was evaluated from distortion of the reflected background. Table 2 shows the results. In addition, the evaluation criteria of visibility are as follows.

◎: Distortion is not observed in the background.

○: Very slight distortion is observed in the background, but there is no problem.

×: Clear distortion is observed in the background.

<Amount of residual solvent>

Using TG-DTA (EXSTAR6000 TG / DTA6300 manufactured by SII Co., Ltd.), the transparent resin films obtained in Examples 1 to 3 and Comparative Example 1 were heated from 30 ° C to 120 ° C and held at 120 ° C for 5 minutes, Thereafter, the temperature was raised to 400 ° C at a rate of 5 ° C / min. The ratio of the mass reduction of the film at 120 ° C to 120 ° C with respect to the mass of the film at 120 ° C was calculated as the content of the solvent (referred to as the residual solvent amount).

 Abbreviations used in the following Production Examples and Examples are as follows.

TFMB: 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl

6FDA: 4,4 '-(hexafluoroisopropylidene) diphthalic acid 2 anhydride

TPC: terephthaloyl chloride

OBBC: 4,4'-oxybis (benzoyl chloride)

DMAc: N, N-dimethylacetamide

GBL: γ-butyrolactone

PET: polyethylene terephthalate

<Manufacturing Example>

Production Example 1: Preparation of polyamideimide resin 1

Under a nitrogen gas atmosphere, a reaction vessel equipped with a stirring vane and an oil bath were prepared in a separable flask. To the reaction vessel installed in the oil bath, 45 parts of TFMB and 768.55 parts of DMAc were charged. TFMB was dissolved in DMAc while the contents in the reaction vessel were stirred at room temperature. Next, 19.01 parts of 6FDA was further added into the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 3 hours. Thereafter, 4.21 parts of OBBC and then 17.30 parts of TPC were added to the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 1 hour. Subsequently, 4.63 parts of 4-methylpyridine and 13.04 parts of acetic anhydride were further added into the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 30 minutes. After stirring, the temperature in the vessel was raised to 70 ° C. using an oil bath, maintained at 70 ° C., and stirred for an additional 3 hours to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread shape, and precipitates were precipitated. The precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ° C to obtain polyamideimide resin 1. The weight average molecular weight of the obtained polyamide-imide resin 1 was 370,000, and the imidation rate was 98.9%.

Production Example 2: Preparation of polyamideimide resin 2

Under a nitrogen gas atmosphere, 50 parts of TFMB and 642.07 parts of DMAc were added to a separable flask equipped with a stirring blade, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 20.84 parts of 6FDA was added to the flask and stirred at room temperature for 3 hours. Thereafter, 9.23 parts of OBBC and then 15.87 parts of TPC were added to the flask and stirred at room temperature for 1 hour. Subsequently, 9.89 parts of 4-methylpyridine and 14.37 parts of acetic anhydride were added to the flask, and after stirring at room temperature for 30 minutes, the temperature was raised to 70 ° C using an oil bath and stirred for another 3 hours to obtain a reaction solution. The resulting reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread shape, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ° C to obtain polyamideimide resin 2. The weight average molecular weight of the obtained polyamide-imide resin 2 was 420,000, and the imidation rate was 99.0%.

Production Example 3: Preparation of polyimide resin

A reactor and an oil bath equipped with a silica gel tube, a stirring device, and a thermometer were prepared in the separable flask. 75.52 parts of 6FDA and 54.44 parts of TFMB were charged into the flask. While stirring at 400 rpm, 519.84 parts of DMAc was added, and stirring was continued until the contents of the flask became a uniform solution. Subsequently, stirring was continued for another 20 hours while adjusting the temperature in the vessel to be in the range of 20 to 30 ° C using an oil bath, and reacted to produce polyamic acid. After 30 minutes, the stirring speed was changed to 100 rpm. After stirring for 20 hours, the reaction system temperature was returned to room temperature, and 649.8 parts of DMAc was added to adjust the polymer concentration to 10% by mass. Further, 32.27 parts of pyridine and 41.65 parts of acetic anhydride were added, and the mixture was stirred at room temperature for 10 hours to imidize. The polyimide varnish was taken out from the reaction vessel. The obtained polyimide varnish was added dropwise to methanol to reprecipitate, and the obtained powder was dried by heating to remove a solvent to obtain a polyimide resin as a solid content. The weight average molecular weight of the obtained polyimide resin was 360,000, and the imidation rate was 98.9%.

Preparation Example 4: Preparation of silica sol 1

Amorphous silica sol having an average primary particle diameter (average primary particle diameter measured by the BET method) of 27 nm prepared as a sol-gel method was used as a raw material, and GBL-substituted silica sol was prepared by solvent substitution. The obtained sol was filtered through a membrane filter having a pore size of 10 µm to obtain GBL-substituted silica sol 1. In the obtained GBL-substituted silica sol 1, the content of silica particles was 30 to 32 mass%.

Preparation Example 5: Preparation of silica sol 2

Amorphous silica sol having an average primary particle diameter of 25 nm produced by the sol-gel method was used as a raw material, and GBL-substituted silica sol was prepared by solvent substitution. The obtained sol was filtered through a membrane filter having a pore size of 10 µm to obtain GBL-substituted silica sol 2. In the obtained GBL-substituted silica sol 2, the content of silica particles was 30 to 32 mass%.

Preparation Example 6: Preparation of varnish (1)

Using the polyamideimide resin 1 obtained in Production Example 1 and the silica sol 1 obtained in Production Example 4, the composition ratio of the polyamideimide resin and the silica particles in the GBL solvent was 60:40. To the resulting mixture, Sumisorb 340 (UVA absorbent) and Sumiplast Violet B (BA, blueing agent) were added in amounts of 5.7 phr and 35 ppm, respectively, based on the total mass of polymer and silica, and stirred until uniform. , Varnish (1) was obtained. The solid content of the varnish (1) was 11.0% by mass, and the viscosity at 25 ° C was 38,500 cps.

Preparation Example 7: Preparation of varnish (2)

A varnish (2) having a solid content of 9.9% by mass and a viscosity at 25 ° C of 38,000 cps was obtained in the same manner as in Production Example 6, except that the polyamideimide resin 2 obtained in Production Example 2 was used.

Production Example 8: Preparation of varnish (3)

A varnish (3) having a solid content of 18.0 mass% and a viscosity at 25 ° C of 35,000 cps was obtained in the same manner as in Production Example 6, except that the polyimide resin obtained in Production Example 3 was used.

Example 1

The varnish (1) was applied onto a PET film (Toyobo Co., Ltd., "Cosmoshine (registered trademark) A4100", film thickness 188 µm, film thickness distribution ± 2 µm), and flexible molded to form a varnish coating film. Did. At this time, the line speed was 0.3 m / min. The coating film of the varnish was heated at 80 ° C for 10 minutes, then heated at 100 ° C for 10 minutes, then heated at 90 ° C for 10 minutes, and finally dried under the drying conditions of heating at 80 ° C for 10 minutes to form a dry coating film. Ordered. Then, the coating film was peeled off from the PET film to obtain a raw film 1 having a thickness of 58 µm and a width of 700 mm. The amount of residual solvent in the raw film 1 was 9.7 mass%. Subsequently, the polyamideimide film 1 with a film thickness of 50 µm was obtained by heating the raw material film 1 with a film transverse stretching device (tenter) at 200 ° C. for 25 minutes and a draw ratio of 0.98 times. The amount of residual solvent in the polyamideimide film 1 was 0.8% by mass.

Example 2

As in Example 1, except that the drying conditions were heated to 80 ° C for 10 minutes, then heated to 100 ° C for 10 minutes, then heated to 90 ° C for 10 minutes, and finally changed to conditions for heating at 85 ° C for 10 minutes. Thus, a raw film 2 having a thickness of 58 µm and a width of 700 mm was obtained. The amount of residual solvent in the raw film 2 was 9.8 mass%. Subsequently, a polyamideimide film 2 having a film thickness of 50 µm was obtained in the same manner as in Example 1 except that the raw film 2 was used instead of the raw film 1. The amount of the residual solvent in the polyamideimide film 2 was 0.7% by mass.

Example 3

The varnish (3) was applied onto a PET film (Toyobo Co., Ltd., Cosmoshine (registered trademark) A4100), film thickness 188 µm, film thickness distribution ± 2 µm), flexible molded to form a varnish coated film. Did. At this time, the line speed was 0.8 m / min. The coating film of the varnish was heated at 100 ° C for 3.5 minutes, then heated at 120 ° C for 3.5 minutes, then heated at 90 ° C for 3.5 minutes, and finally dried under drying conditions of heating at 80 ° C for 3.5 minutes to form a dry coating film. Ordered. Then, the coating film was peeled from the PET film to obtain a raw film 3 having a thickness of 58 µm and a width of 700 mm. The amount of residual solvent in the raw film 3 was 9.5 mass%. Subsequently, a polyimide film having a thickness of 50 µm was obtained in the same manner as in Example 1 except that the raw film 3 was used instead of the raw film 1. The amount of residual solvent in the polyimide film was 1.0 mass%.

Comparative Example 1

Using the varnish (2), the drying conditions were changed to conditions of heating at 70 ° C for 10 minutes, heating at 80 ° C for 10 minutes, then heating at 100 ° C for 10 minutes, and finally heating at 100 ° C for 10 minutes. A raw material film 4 having a thickness of 58 µm and a width of 700 mm was obtained in the same manner as in Example 1 except for doing it. The amount of residual solvent in the raw film 4 was 9.7 mass%. Subsequently, a polyamideimide film 3 having a thickness of 50 µm was obtained in the same manner as in Example 1 except that the raw film 3 was used instead of the raw film 1. The amount of the residual solvent in the obtained polyamideimide film 3 was 0.7% by mass.

Reference Example 1

A polyamideimide resin 3 was obtained in the same manner as in Production Example 1 except that the amount of DMAc introduced was 1650 parts. The weight average molecular weight of the obtained polyamideimide resin 3 was 180,000. A varnish was prepared in the same manner as in Production Example 6 except that polyamideimide resin 3 was used instead of polyamideimide resin 1, and a film having a thickness of 50 µm for reference was prepared in the same manner as in Example 1 using the varnish.

Table 1 shows the physical properties of the varnish used in the production of the films of Examples and Comparative Examples, and the conditions for the first drying. In addition, the results obtained by measuring various physical property values according to the above measuring methods for the films obtained in Examples and Comparative Examples are shown in Tables 2-4. In addition, Table 3 shows the results of the bending resistance test for the film shown in Reference Example 1.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

In the optical films of Examples 1 to 3, Y _mh and Y _mv were less than 30, A / B was less than 30, and evaluation of visibility was all ◎ or ○. On the other hand, in the optical film of Comparative Example 1, A / B was 30 or more, and the evaluation result of visibility was x. Moreover, the film of Reference Example 1 containing a resin having a weight average molecular weight of less than 230,000 did not have sufficient bending resistance.

1: light source
2: Film
3: Projection plane
4: Projected image
5: Optical
6: Camera
7: Camera angle

Claims (9)

An optical film comprising at least one of a polyimide resin and a polyamide resin having a weight average molecular weight of 230,000 or more, and a filler having an average primary particle diameter of 5 to 35 nm, a projection image obtained by a projection method using the optical film The line profiles in directions h and v that are orthogonal to each other on the film inverse space obtained by Fourier transform are referred to as line profiles h and line profiles v, respectively, and the background image obtained without using the optical film in the projection method. In the background inverse space obtained by Fourier transform, line profiles in directions h 'and v which are orthogonal to each other are referred to as line profiles h' and line profiles v ', respectively, and line profile h' is subtracted from line profile h. The maximum intensity of the obtained line profile (h-h ') is called Y _mh , and the frequency representing the maximum intensity Y _mh If the number is X _mh , the maximum intensity of the line profile (v-v ') obtained by subtracting the line profile v' from the line profile v is Y _mv , and the frequency representing the maximum intensity Y _mv is X _mv , then Y _mh And Y _mv are all 30 or less, and Y _mh , Y _mv , X _mh and X _mv are the following relationships:

Satisfying, optical film. According to claim 1,
The optical film of which the yellowness of the film is 3 or less. According to claim 1,
The filler is an silica particle, an optical film. According to claim 1,
The content of the filler is 5 to 60% by mass based on the mass of the optical film. According to claim 1,
An optical film that is a film for a front panel of a flexible display device. A flexible display device comprising the optical film according to any one of claims 1 to 5. The method of claim 6,
A flexible display device further comprising a touch sensor. The method of claim 6,
A flexible display device further comprising a polarizing plate. (a) At least one of a polyimide resin and a polyamide resin having a weight average molecular weight of 230,000 or more, a filler having an average primary particle diameter of 5 to 35 nm, and a varnish containing at least a solvent are coated on a support and dried. , Process of forming a coating film,
(b) a step of peeling off the coating film from the support, and
(c) a step of heating the peeled coating film to obtain a film,
The manufacturing method of the optical film in any one of Claims 1-5 containing at least.

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