WO2018062031A1

WO2018062031A1 - Optical film and method for manufacturing same

Info

Publication number: WO2018062031A1
Application number: PCT/JP2017/034272
Authority: WO
Inventors: 池内　淳一; 幸二朗西; 幸治植田
Original assignee: 住友化学株式会社
Priority date: 2016-09-30
Filing date: 2017-09-22
Publication date: 2018-04-05
Also published as: KR20180045891A; JP7021887B2; JP2018059070A; TWI757346B; KR20190049786A; CN109790308B; CN109790308A; TW201817780A

Abstract

Provided is an optical film in which cracks are unlikely to form in end parts even if preserved in a high-temperature, high-humidity environment in a deformed state. This optical film comprises a polyimide polymer including an intramolecular fluorine atom, the atomic ratio (F/C) of fluorine atoms relative to carbon atoms at the end surfaces of the optical film as measured using X-ray photoelectron spectroscopy being greater than the atomic ratio (F/C) of fluorine atoms relative to carbon atoms in sections cut 1 mm inside from the end surfaces of the optical film as measured using X-ray photoelectron spectroscopy.

Description

Optical film and manufacturing method thereof

The present invention relates to an optical film, a manufacturing method thereof, and a flexible device.

Conventionally, glass has been used as a base material for various display members such as solar cells and displays, and as a material for transparent members such as front plates. However, glass has drawbacks such as being easily broken and heavy. In addition, the display has not been made of a sufficient material to meet the recent demands for thinner and lighter displays and more flexible displays. Therefore, various films (optical films) have been studied as transparent members for flexible devices that replace glass.

For example, Patent Document 1 discloses a polyimide film that is formed using a polyimide resin composition and is excellent in transparency, flexibility, folding resistance, and the like.

JP 2009-215412 A

When used for curved displays, foldable devices, rollable displays, etc., the optical film is stored in a deformed state such as a rolled state (rolled state) or a bent state. May be. However, the conventional polyimide film has a problem that cracks are likely to occur at the end when stored in a high temperature and high humidity environment in a deformed state such as a rolled state or a bent state.

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an optical film in which cracks are unlikely to occur at the end even when stored in a high temperature and high humidity environment in a deformed state. And Another object of the present invention is to provide a method for producing the optical film, a front plate for a flexible device using the optical film, and a flexible device.

In order to achieve the above object, the present invention provides an optical film containing a polyimide-based polymer containing a fluorine atom in the molecule, wherein the fluorine atom measured by X-ray photoelectron spectroscopy at the end face of the optical film is provided. The atomic ratio (F / C) to carbon atoms is higher than the atomic ratio (F / C) of fluorine atoms to carbon atoms measured by X-ray photoelectron spectroscopy in a cross section obtained by cutting 1 mm inside from the end face of the optical film. Provide a large optical film.

According to the optical film, the atomic ratio (F / C) at the end face is larger than the atomic ratio (F / C) in a cross section cut 1 mm inside from the end face, whereby the optical film is wound in a roll shape. Even when stored in a high-temperature and high-humidity (for example, 85 ° C., 85% RH) environment with the end face deformed by bending or bending, the occurrence of cracks from the end face can be suppressed. . When stored in a high-temperature and high-humidity environment in a deformed state, in addition to deformation caused by rolling or bending, thermal expansion and hygroscopic expansion cause complex stresses around the edges, causing cracks. However, it is considered that the complicated stress can be suppressed in a film having a relatively large number of fluorine atoms on the end face as compared with the inside of the film.

The optical film has an atomic ratio (F _E / C _E ) of fluorine atoms to carbon atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film, and a cross section obtained by cutting 1 mm inside from the end face of the optical film. The ratio (F _E / C _E ) / (F _C / C _C ) of the atomic ratio of fluorine atoms to carbon atoms (F _C / C _C ) measured by X-ray photoelectron spectroscopy in FIG. There may be.

The present invention is also an optical film containing a polyimide-based polymer containing a fluorine atom in the molecule, the atomic ratio of the fluorine atom to the oxygen atom (F) measured by X-ray photoelectron spectroscopy at the end face of the optical film. / O) provides an optical film having a larger atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy in a cross section cut 1 mm inside from the end face of the optical film. .

According to the optical film, the atomic ratio (F / O) at the end face is larger than the atomic ratio (F / O) in a cross section cut 1 mm inside from the end face, whereby the optical film is wound in a roll shape. Even when stored in a high-temperature and high-humidity (for example, 85 ° C., 85% RH) environment with the end face deformed by bending or bending, the occurrence of cracks from the end face can be suppressed. . When stored in a high-temperature and high-humidity environment in a deformed state, in addition to deformation caused by rolling or bending, thermal expansion and hygroscopic expansion cause complex stresses around the edges, causing cracks. However, it is considered that the complicated stress can be suppressed in a film having a relatively large number of fluorine atoms on the end face as compared with the inside of the film.

The optical film has an atomic ratio (F _E / O _E ) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film, and a cross section obtained by cutting 1 mm inside from the end face of the optical film. The ratio (F _E / O _E ) / (F _C / O _C ) of the atomic ratio of fluorine atoms to oxygen atoms (F _C / O _C ) measured by X-ray photoelectron spectroscopy in FIG. There may be.

The optical film may further contain silica particles.

The present invention is also a method for producing an optical film containing a polyimide-based polymer containing a fluorine atom in the molecule, which is measured by X-ray photoelectron spectroscopy at the end face of the optical film by oxidizing the end face. The atomic ratio (F / C) of the fluorine atom to the carbon atom is determined by measuring the atomic ratio of the fluorine atom to the carbon atom (F / C) measured by X-ray photoelectron spectroscopy in a cross section cut 1 mm inside from the end face of the optical film. The manufacturing method of an optical film which has the process made larger than C) is provided.

By the above manufacturing method, it is possible to manufacture an optical film in which cracks are hardly generated at the end portion even when stored in a high temperature and high humidity environment in a deformed state.

The present invention is also a method for producing an optical film containing a polyimide-based polymer containing a fluorine atom in the molecule, wherein the end face of the optical film is formed by cutting the film original by laser irradiation. The atomic ratio (F / C) of fluorine atoms to carbon atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film is measured by X-ray photoelectron spectroscopy at a cross section taken 1 mm inside from the end face of the optical film. Provided is a method for producing an optical film, which comprises a step of making the atomic ratio (F / C) of fluorine atoms to carbon atoms measured by the method larger.

The present invention is also a method for producing an optical film containing a polyimide-based polymer containing a fluorine atom in the molecule, which is measured by X-ray photoelectron spectroscopy at the end face of the optical film by oxidizing the end face. The atomic ratio (F / O) of fluorine atoms to oxygen atoms is determined by measuring the atomic ratio of fluorine atoms to oxygen atoms (F / O) measured by X-ray photoelectron spectroscopy in a cross section cut 1 mm inside from the end face of the optical film. The manufacturing method of an optical film which has the process made larger than O) is provided.

The present invention is also a method for producing an optical film containing a polyimide-based polymer containing a fluorine atom in the molecule, wherein the end face of the optical film is formed by cutting the film original by laser irradiation. The atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film is measured by X-ray photoelectron spectroscopy at a cross section taken 1 mm inside from the end face of the optical film. Provided is a method for producing an optical film, which comprises a step of making the atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by the method larger.

The present invention also provides a front plate for a flexible device having the optical film of the present invention.

The present invention further provides a flexible device having a flexible functional layer and the optical film of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, even if it stores in the high-temperature, high-humidity environment in the deformed state, the optical film which is hard to generate | occur | produce a crack at an edge part, its manufacturing method, the front plate for flexible devices using the said optical film, and flexible A device can be provided.
Can be obtained.

FIG. 1 is a perspective view showing an example of an optical film according to an embodiment of the present invention. FIG. 2 is a perspective view showing an example of a flexible display according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as the case may be.
In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

The optical film of this embodiment contains a polyimide polymer containing a fluorine atom in the molecule, and satisfies one or both of the following conditions (1) and (2).
Condition (1): The atomic ratio (F / C) of fluorine atoms to carbon atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film is X in a cross section obtained by cutting 1 mm inside from the end face of the optical film. It is larger than the atomic ratio (F / C) of the fluorine atom to the carbon atom measured by line photoelectron spectroscopy.
Condition (2): The atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film is X in a cross section cut 1 mm inside from the end face of the optical film. It is larger than the atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by linear photoelectron spectroscopy.

FIG. 1 is a perspective view showing an example of an optical film according to this embodiment. The optical film 10 shown in FIG. 1 has a rectangular (rectangular) planar shape, and has end faces E1 and E2 of two sides (two long sides parallel to each other forming a rectangle) facing each other in the short direction. And end faces E3 and E4 of two sides (two short sides parallel to each other forming a rectangle) facing each other in the longitudinal direction. The optical film 10 has X in each of the end faces E1 to E4 and the cross sections C1 to C4 when the cut surfaces cut by 1 mm from the end faces E1, E2, E3, and E4 are cross sections C1, C2, C3, and C4, respectively. ray photoelectron spectroscopy atomic ratio carbon atoms of fluorine atoms measured in (XPS) (F / C) , in whole or in part of the end _surface, F _E / _C E is greater than _F _C / C C, and / Or the atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy (XPS) in each of the end faces E1 to E4 and the cross sections C1 to C4 is the whole or a part of the end face _in, F _E / _O E is greater than _F _C / _O C. Note that the atomic ratio of fluorine atoms to carbon atoms measured by XPS at the end face is F _E / C _E, and the atomic ratio of fluorine atoms to carbon atoms measured by XPS in the cross section is F _C / _CC, and at the end face the atomic ratio of oxygen atoms of fluorine atom, measured by XPS and F _{_E /} O _E, the atomic ratio of oxygen atoms of fluorine atom, measured by XPS in the cross section and F _{_C /} O _C. As an optical film for a foldable device having a quadrangular display, it is preferable to satisfy either of the following conditions (I) and (II), and more preferable to satisfy both.
In (I) the end faces _{_{E1, E2, F E / C}} E is greater than _F C / _{C C,} and / _or, F E / _{O E} is greater than _F C / _{O C.}
In (II) an end face _{_{E3, E4, F E / C}} E is greater than _F C / _{C C,} and / _or, F E / _{O E} is greater than _F C / _{O C.}

It optical film 10 satisfies the condition above, namely, _F E / _{C E} is greater than _F C / _{C C} at the end face, and / _or, by F E / _{O E} is greater than _F C / _{O C} Even when the optical film 10 is deformed and stored in a high-temperature and high-humidity environment, generation of cracks from the end face can be suppressed. From the viewpoint of suppressing the occurrence of cracks from all end faces, the optical film 10 preferably satisfies both the above conditions (I) and (II).

Since cracks are likely to occur from the end face where deformation occurs, from the viewpoint of efficiently preventing such cracks, F _E / C _E is larger than F _C / C _C and / or F _E / O _E is F _An end face larger than _{C 1} / O 2 _C can be a face where deformation such as bending occurs when the optical film is bent (for example, during storage or use). For example, when an optical film having a rectangular planar shape is stored by being bent around the short direction of the optical film or wound in a roll shape, end faces on two sides facing each other in the short direction (for example, in FIG. 1) In the case of the optical film 10 shown, the end faces E1 and E2) are deformed by bending. In such a case, it is preferable that fluorine atoms are present at a higher concentration than the inside of the film, at least on the end surfaces of the two sides facing each other in the lateral direction of the optical film.

When the optical film is used as a member of a flexible display, the end of the portion where the film is deformed inside the display has F _E / C _E larger than F _C / C _C and / or F _E / O _E by has a F C _/ O _C greater end face than can be deteriorated due to crack from the end portion is suppressed to obtain a higher reliability. For example, in the case of a display having a curved surface, an end portion having a _curvature, F E / _{C E} is greater than _F C / _{C C,} and / _or, than F E / _{O E} is _F C / _{O C} If the end face is large, the effect of the present invention tends to be easily obtained. Also, in the case of a foldable device, the end on the side bent by folding is such that F _E / C _E is greater than F _C / C _C and / or F _E / O _E is greater than F _C / O _C If the end face is too large, the effect of the present invention tends to be easily obtained. In the case of a display that can be rounded, the edge with curvature by rounding is such that F _E / C _E is greater than F _C / C _C and / or F _E / O _E is F _C / O _{If the} end face is larger than _C, the effect of the present invention tends to be easily obtained.

The XPS measurement of the end face and the cross section of the optical film can be performed under the following conditions. Moreover, XPS measurement can be performed by irradiating X-rays from the direction perpendicular to the end face or cross section of the optical film and detecting photoelectrons from the 45 ° direction.

<XPS measurement conditions>
Equipment: Quantera SXM (manufactured by ULVAC PHI)
X-ray: AlKα ray (1486.6 eV)
X-ray spot diameter: 50 μm
Neutralization conditions: neutralization electron (1 eV), low-speed Ar ion (10 eV)

The atomic ratio (F / C) of fluorine atoms to carbon atoms and / or the atomic ratio of fluorine atoms to oxygen atoms (F / O) measured by XPS can be determined from the areas of the C1s, O1s and F1s peaks in the XPS spectrum. Can be sought.

The cutting of the optical film at the time of forming the cross section for performing XPS measurement (cross sections C1 to C4 in the optical film 10) is performed by a method in which the atomic composition of the cut surface does not change and the cut surface is not distorted. The cutting can be performed using, for example, a razor.

In the end face of the optical film 10 according to an embodiment of the present invention, the value of (F _E / C _E ) / (F _C / C _C ) needs to be a value greater than 1, but 1.1. Is preferably 10 to 10, more preferably 1.5 to 8, and still more preferably 2 to 5. When this value is 1.1 or more, the fluorine atom concentration at the film end face is sufficiently higher than the fluorine atom concentration at the film cross section (inside the film), and the occurrence of cracks from the end face is more sufficiently suppressed. There is a tendency to be able to.

In the optical film 10, the value of F _E / C _{E at} the end face where the value of (F _E / C _E ) / (F _C / C _C ) is greater than 1 is preferably 0.03 or more, and 0.04 More preferably, it is more preferably 0.05 or more. When the value of F _{E /} C _E of the end surface is 0.03 or more, there is a tendency that it is possible to more sufficiently suppress the occurrence of cracks from the end surface.

An end face having a value of (F _E / C _E ) / (F _C / C _C ) greater than 1 can be formed by laser cutting. In the end face formed by the above method, the value of (F _E / C _E ) / (F _C / C _C ) tends to be larger than 1, and the generation of cracks from the end face can be more sufficiently suppressed. Tend.

In the end face of the optical film 10 according to another embodiment of the present invention, the value of (F _E / O _E ) / (F _C / O _C ) needs to be greater than 1, but 1 It is preferably 1 to 10, more preferably 1.3 to 8, and still more preferably 1.5 to 5. When this value is 1.1 or more, the fluorine atom concentration at the film end face is sufficiently higher than the fluorine atom concentration at the film cross section (inside the film), and the occurrence of cracks from the end face is more sufficiently suppressed. There is a tendency to be able to.

In the optical film 10, the value of F _E / O _{E at} the end face where the value of (F _E / O _E ) / (F _C / O _C ) is greater than 1 is preferably 0.2 or more. When the value of F _{E /} O _E of the end face is 0.2 or more, there is a tendency that it is possible to more sufficiently suppress the occurrence of cracks from the end surface.

The end face having a value of (F _E / O _E ) / (F _C / O _C ) greater than 1 can be formed by laser cutting. In the end face formed by the above method, the value of (F _E / O _E ) / (F _C / O _C ) tends to be larger than 1, and the occurrence of cracks from the end face can be more sufficiently suppressed. Tend.

The refractive index of the optical film 10 is usually 1.45 to 1.70, preferably 1.50 to 1.66.

The thickness of the optical film 10 is appropriately adjusted according to the type of the flexible device and the like, but is usually 10 to 500 μm, preferably 15 to 200 μm, and more preferably 20 to 100 μm.

The optical film 10 is usually transparent. The optical film 10 has a total light transmittance based on JIS K 7105: 1981 of usually 85% or more, preferably 90% or more.

The optical film 10 can have a haze based on JIS K 7105: 1981 of 1 or less, or 0.9 or less.

Note that the refractive index, total light transmittance, and Haze are values measured in the thickness direction of the optical film.

The size of the optical film 10 can be appropriately adjusted according to the size of the flexible device used. The planar shape of the optical film 10 is usually a rectangle or a square, but may be another rectangle such as a trapezoid or a parallelogram. The planar shape of the optical film 10 may be a quadrangle with rounded corners.

(Material of film)
(Transparent resin)
The optical film contains a transparent resin such as a polyimide polymer containing fluorine atoms in the molecule.

(Polyimide polymer)
In this specification, a polyimide is a polymer containing a repeating structural unit containing an imide group, and a polyamide is a polymer containing a repeating structural unit containing an amide group. The polyimide-based polymer refers to a polymer containing a polyimide and a repeating structural unit containing both an imide group and an amide group.

The polyimide polymer according to the present embodiment can be produced using a tetracarboxylic acid compound and a diamine compound described later as main raw materials, and has a repeating structural unit represented by the formula (10). Here, G is a tetravalent organic group, and A is a divalent organic group. The structure represented by two or more types of Formula (10) from which G and / or A differ may be included.

In addition, the polyimide polymer according to the present embodiment includes a structure represented by any one of formulas (11) to (13) as long as various physical properties of the resulting polyimide polymer film are not impaired. Also good.

G and G ¹ are tetravalent organic groups, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and are represented by formula (20), formula (21), formula ( 22), the formula (23), the formula (24), the formula (25), the formula (26), the formula (27), the group represented by the formula (28) or the formula (29), and a tetravalent carbon number of 6 or less. The chain hydrocarbon group is exemplified. In the formula * represents a bond, Z is a single _{_{_{bond, -O -, - CH 2 -}}} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, —C (CF ₃ ) ₂ —, —Ar—, —SO ₂ —, —CO—, —O—Ar—O—, —Ar—O—Ar—, —Ar—CH ₂ —Ar—, —Ar— C (CH ₃ ) ₂ —Ar— or —Ar—SO ₂ —Ar— is represented. Ar represents an arylene group having 6 to 20 carbon atoms which may be substituted with a fluorine atom, and specific examples thereof include a phenylene group. G and G ¹ are preferably any group selected from the groups represented by formulas (20) to (27) because the yellowness of the resulting film can be easily suppressed.

G ² is a trivalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and has the formula (20), formula (21), formula (22) Any one of the bonds of the group represented by formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29) is a hydrogen atom And a trivalent chain hydrocarbon group having 6 or less carbon atoms are exemplified.

G ³ is a divalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and is represented by formula (20), formula (21), formula (22) Among the bonds of the group represented by formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29), Examples thereof include a group replaced with a hydrogen atom and a chain hydrocarbon group having 6 or less carbon atoms.

Each of A and A ¹ to A ³ is a divalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. 31), a group represented by formula (32), formula (33), formula (34), formula (35), formula (36), formula (37) or formula (38); they are a methyl group, a fluoro group And a group substituted with a chloro group or a trifluoromethyl group, and a chain hydrocarbon group having 6 or less carbon atoms. In the formula * represents a ^bond, Z 1, ^{Z 2} and ^{Z 3} are each independently a single _{_{bond, -O -, - CH 2 -}} , - CH 2 -CH 2 -, - CH (CH 3 )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ -or -CO-. One example is when Z ¹ and Z ³ are —O— and Z ² is —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or —SO ₂ —. is there. Z ¹ and Z ² , and Z ² and Z ³ are each preferably in the meta position or the para position with respect to each ring.

The optical film may contain polyamide. The polyamide according to this embodiment is a polymer mainly composed of repeating structural units represented by the formula (13). Preferred examples and specific examples are the same as G ³ and A ³ in the polyimide polymer. G ³ and / or A ³ may contain structures represented by two or more types of formula (13).

The polyimide polymer is obtained, for example, by polycondensation of a diamine and a tetracarboxylic acid compound (tetracarboxylic dianhydride or the like), and is described in, for example, JP-A-2006-199945 or JP-A-2008-163107. It can be synthesized according to the method. Examples of commercially available polyimide products include Neoprim produced by Mitsubishi Gas Chemical Co., Ltd. and KPI-MX300F produced by Kawamura Sangyo Co., Ltd.

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

Specific examples of the aromatic tetracarboxylic dianhydride include 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3, 3'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-Diphenylsulfonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane Dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride, 1,2-bis (2,3 -The Ruboxyphenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1 -Bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4 ' -(P-phenylenedioxy) diphthalic dianhydride, 4,4 '-(m-phenylenedioxy) diphthalic dianhydride and 2,3,6,7-naphthalenetetracarboxylic dianhydride Preferably 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 3, ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4- Dicarboxyphenoxyphenyl) propane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride, 1,2-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1- Bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane anhydrous Bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4 ′-(p-phenylenedioxy) diphthalic dianhydride and 4,4 ′-(m-phenylenedioxy) diphthalic dianhydride is mentioned. These can be used alone or in combination of two or more.

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

Among the above tetracarboxylic dianhydrides, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene are used from the viewpoint of high transparency and low colorability. -2,3,5,6-tetracarboxylic dianhydride and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride are preferred.

In addition, in addition to the tetracarboxylic acid anhydride used for the above-mentioned polyimide synthesis, the polyimide polymer according to the present embodiment is within a range that does not impair various physical properties of the obtained polyimide polymer film. Further, tricarboxylic acid and dicarboxylic acid and anhydrides and derivatives thereof may be further reacted.

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

Examples of the dicarboxylic acid compound include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and related acid chloride compounds, acid anhydrides, and the like, and two or more kinds may be used in combination. Specific examples include dicarboxylic acid compounds of terephthalic acid; isophthalic acid; naphthalenedicarboxylic acid; 4,4′-biphenyldicarboxylic acid; 3,3′-biphenyldicarboxylic acid; And a compound in which two benzoic acids are linked by a single bond, —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —SO ₂ —, or a phenylene group.

The diamine used for the synthesis of the polyimide polymer may be an aliphatic diamine, an aromatic diamine or a mixture thereof. In the present embodiment, the “aromatic diamine” represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group or other substituent may be included in a part of the structure. The aromatic ring may be a single ring or a condensed ring, and examples thereof include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among these, a benzene ring is preferable. The “aliphatic diamine” refers to a diamine in which an amino group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be included in a part of the structure.

Examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylene diamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornane diamine, 4,4′- Examples include cycloaliphatic diamines such as diaminodicyclohexylmethane, and these can 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 and 2,6-diaminonaphthalene. Aromatic diamine having one aromatic ring, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3 ′ -Diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis ( 4-Aminophenoxy) benzene, 4,4'-diaminodiph Nylsulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2, 2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2′-dimethylbenzidine, 2,2′-bis (trifluoromethyl) benzidine, 4,4′-bis (4-aminophenoxy) biphenyl 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3- Methylphenyl) fluorene, 9,9-bis (4-amino-3-chlorophenyl) fluorene, 9,9-bis (4 Such as an amino-3-fluorophenyl) fluorene, an aromatic diamine are exemplified having two or more aromatic rings, they may be used alone or in combination of two or more.

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

Polyimide polymers and polyamides, which are polymers containing at least one repeating structural unit represented by any one of formulas (10) to (13), include diamines, tetracarboxylic acid compounds (acid chloride compounds, tetracarboxylic acids). Tetracarboxylic acid compound analogs such as acid dianhydrides), tricarboxylic acid compounds (acid chloride compounds, tricarboxylic acid compound analogs such as tricarboxylic acid anhydrides) and dicarboxylic acid compounds (dicarboxylic acid compound analogs such as acid chloride compounds) A condensation polymer which is a polycondensation product with at least one compound included in the group consisting of In addition to these, a dicarboxylic acid compound (including analogs such as an acid chloride compound) may be used as a starting material. The repeating structural unit represented by the formula (11) is usually derived from diamines and tetracarboxylic acid compounds. The repeating structural unit represented by the formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by the formula (13) is usually derived from a diamine and a dicarboxylic acid compound. Specific examples of the diamine and the tetracarboxylic acid compound are as described above.

The standard polystyrene equivalent weight average molecular weight of the polyimide polymer and the polyamide according to this embodiment is usually 10,000 to 500,000, preferably 50,000 to 500,000, and more preferably 100,000. ~ 400,000. The higher the weight average molecular weight of the polyimide polymer and polyamide, the higher the tendency to exhibit high bending resistance when filmed. However, if the weight average molecular weight of the polyimide polymer is too large, the viscosity of the varnish will increase. , Workability tends to decrease.

By including a fluorine-containing substituent, the polyimide polymer and polyamide tend to improve the elastic modulus when formed into a film, reduce the YI value, and improve transparency.
When the elastic modulus of the film is high, generation of scratches and wrinkles tends to be suppressed. In addition, the polyimide-based polymer containing a fluorine atom in the molecule is the value of (F _E / C _E ) / (F _C / C _C ) and / or (F _E / O _E ) / (F _C By having an end face having a value of / O _C ) greater than 1, even when stored in a high temperature and high humidity environment in a deformed state, occurrence of cracks from the end portion can be sufficiently suppressed. Specific examples of the fluorine-containing substituent include a fluoro group and a trifluoromethyl group.

(Polyimide polymer containing fluorine atoms in the molecule)
The polyimide polymer containing a fluorine atom in the molecule is fluorine-substituted at least one of G, G ¹ to G ³ , A, A ¹ to A ³ and Ar in the molecular structure of the polyimide polymer. It has a group. The content of fluorine atoms in the polyimide-based polymer containing fluorine atoms in the molecule is preferably 1% by mass or more and 40% by mass or less, more preferably 5% by mass or more and 40% by mass based on the mass of the polyimide-based polymer. It is below mass%. When the fluorine atom content is 1% by mass or more, there is a tendency that the elastic modulus when formed into a film is further improved, the YI value is further reduced, and the transparency is further improved. When the fluorine atom content is 40% by mass or less, cost and reactivity during synthesis tend to be advantageous.

In the optical film according to this embodiment, the content of the polyimide-based polymer is usually 30% by mass or more, preferably 40% by mass or more, and more preferably 50% by mass based on the total mass of the optical film. % Or more. When the content of the polyimide polymer is 30% by mass or more, the flex resistance of the film tends to be advantageous.

(Inorganic particles)
The optical film according to the present embodiment may further contain an inorganic material such as inorganic particles in addition to the polyimide polymer.

Preferred examples of the inorganic material include silica particles and silicon compounds such as quaternary alkoxysilanes such as tetraethyl orthosilicate (TEOS), and silica particles are preferable from the viewpoint of varnish stability.

The average primary particle diameter of the silica particles is preferably 10 to 100 nm, more preferably 20 to 80 nm. When the average primary particle diameter of the silica particles is 100 nm or less, the transparency tends to be improved. When the average primary particle diameter of the silica particles is 10 nm or more, the cohesive force of the silica particles is weakened, and thus the handling tends to be easy.

The silica fine particles according to the present embodiment may be a silica sol in which silica particles are dispersed in an organic solvent or the like, or a silica fine particle powder produced by a vapor phase method may be used. Preferably there is.

The (average) primary particle diameter of the silica particles in the optical film can be determined by observation with a transmission electron microscope (TEM). The particle size distribution of the silica particles before forming the optical film can be determined by a commercially available laser diffraction particle size distribution meter.

In the optical film according to this embodiment, the content of the inorganic material is usually 0% by mass or more and 70% by mass or less, preferably 0% by mass or more and 60% by mass or less, based on the total mass of the optical film. More preferably, it is 0 mass% or more and 50 mass% or less. When the content of the inorganic material (silicon material) is within the above range, the optical film tends to have both transparency and mechanical strength.

The optical film according to the present embodiment may further contain additives in addition to the components described above. Examples of the additives include pH adjusters, silica dispersants, ultraviolet absorbers, antioxidants, mold release agents, stabilizers, coloring agents such as bluing agents, flame retardants, lubricants, and leveling agents.

The content of components other than the resin component and the inorganic material is preferably 0% by mass or more and 20% by mass or less, more preferably more than 0% by mass and 10% by mass or less, based on the total mass of the optical film.

(Optical film manufacturing method)
Next, an example of the manufacturing method of the optical film of this embodiment is demonstrated.

The varnish used for the production of the optical film according to the present embodiment is, for example, a reaction solution of a polyimide polymer, a solvent obtained by selecting and reacting from the tetracarboxylic acid compound, the diamine, and the other raw materials, and It can prepare by mixing and stirring the said additive used as needed. Instead of a reaction solution such as a polyimide polymer, a solution such as a purchased polyimide polymer or a solution such as a purchased solid polyimide polymer may be used.

The solvent contained in the varnish only needs to dissolve the polyimide polymer. Examples of the solvent include amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide, lactone solvents such as γ-butyrolactone and γ-valerolactone, and sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide, and sulfolane. A carbonate solvent such as a solvent based on ethylene carbonate or propylene carbonate can be used. Among these solvents, amide solvents or lactone solvents are preferable. Moreover, you may use these solvents individually or in mixture of 2 or more types.

Next, a coating film is formed by applying the above varnish on a resin substrate, a stainless steel belt, or a glass substrate by a known roll-to-roll or batch method, and the coating film is dried. By peeling from the film, a film containing a polyimide polymer is obtained. The film may be further dried after peeling.

The coating film is dried by evaporating the solvent at a temperature of 50 to 350 ° C. Drying may be performed under air, under an inert atmosphere, or under reduced pressure.

Examples of the resin substrate include PET, PEN, polyimide, polyamideimide and the like. Among these, a resin excellent in heat resistance is preferable. In particular, a PET substrate is preferable from the viewpoints of adhesion to the film and cost.

Subsequently, the atomic ratio of fluorine atoms to carbon atoms (F _E / C _E ) and / or the atomic ratio of fluorine atoms to oxygen atoms (F _E / O) measured by XPS with respect to the end face of the film. _E ) is an atomic ratio (F _C / C _C ) of fluorine atoms to carbon atoms and / or an atomic ratio of fluorine atoms to oxygen atoms (measured by XPS) with respect to a cross section cut inside 1 mm from the end face by a razor Processing is performed so as to be larger than F _E / O _E ).

The present invention also includes a method for oxidizing the end face of an optical film containing a polyimide polymer and a method for irradiating a laser. By these methods, it is possible to obtain a film containing a polyimide-based polymer in which cracks are unlikely to occur at the end even when stored in a high temperature and high humidity environment in a deformed state.

The laser that can be used for laser irradiation is not particularly limited, and any laser can be used. Specific examples of usable lasers include gas lasers such as CO ₂ lasers and excimer lasers; solid state lasers such as YAG lasers; and semiconductor lasers. A suitable laser that can be used for laser irradiation is a CO ₂ laser. Specifically, by cutting the polyimide-based polymer film raw material into a desired size with a CO ₂ laser, cracks are unlikely to occur at the edges even when stored in a high temperature and high humidity environment in a deformed state. A film containing a polyimide polymer can be easily obtained. End face oxidation may be performed by laser irradiation.

Laser irradiation makes the atomic ratio (F _E / C _E ) of the film end face easily and sufficiently higher than the atomic ratio (F _C / C _C ) inside the film and / or the atomic ratio (F From the viewpoint of easily and sufficiently making _E / O _E ) higher than the atomic ratio (F _C / O _C ) inside the film, it is preferable to carry out the following conditions. That is, the laser is preferably a CO ₂ laser, and more preferably a wavelength of 10 μm or less. It is preferable for the output to be a condition capable of cutting the film because the amount of fluorine at the end can be increased simultaneously with the cutting. The output is preferably 10 W or more, and more preferably 12 W or more. The laser processing speed is preferably 50 mm / sec or more, and more preferably 100 mm / sec or more. The end portion may be irradiated with a laser a plurality of times.

When the obtained optical film is used for, for example, a display having a curved surface, a foldable device, a display that can be rolled, etc., it is deformed such as a rolled state (rolled state) or a bent state. May be stored in a damaged state. At this time, the end surface of the optical film is in a deformed state. In addition, the deformed optical film may be placed in a high temperature and high humidity environment during storage. When stored in a high temperature and high humidity environment with the optical film deformed in this way, the conventional optical film has a problem that cracks are likely to occur at the end, but according to the optical film of the present embodiment, _F E / _{C E} is higher than the _F C / _{C C} at the end face, and / _or, by F E / _{O E} is higher than the _F C / _{O C,} possible to suppress the occurrence of cracks in the end Can do.

(Use)
Such an optical film can be suitably used as a front plate of a flexible device. The flexible device which concerns on this embodiment has a flexible functional layer and said optical film which overlaps with a flexible functional layer and functions as a front plate. That is, the front plate of the flexible device is disposed on the viewing side on the flexible functional layer. This front plate has a function of protecting the flexible functional layer.

Examples of flexible devices include image display devices (flexible displays, electronic paper, etc.), solar cells, and the like. For example, a display functional layer and a solar cell functional layer are flexible functional layers.

An example of a flexible display is shown in FIG. This flexible display 100 is called front plate 110 / polarizing plate protective film 120B / polarizer 120A / polarizing plate protective film 120B / touch sensor film 130 / organic EL element layer 140 / TFT substrate 150 in this order from the surface side (viewing side). It has a configuration. A layer other than the front plate 110 in the flexible display 100 is the flexible functional layer 190. The polarizing plate protective film 120 </ b> B / polarizer 120 </ b> A / polarizing plate protective film 120 </ b> B constitutes the polarizing plate 120. A hard coat layer, an adhesive layer, an adhesive layer, a retardation layer, and the like may be included between the surface of each layer and each interlayer. The optical film 10 described above can be used as the front plate 110. Such a flexible display can be used as an image display unit of a tablet PC, a smartphone, a portable game machine, or the like.

According to the flexible device according to the present embodiment, the optical film 10 is used as the front plate 110. Since the optical film 10 is suppressed from generating cracks from the end face, the reliability can be improved.

In addition, it can also be set as the laminated body which added various functional layers, such as an ultraviolet absorption layer, a hard-coat layer, an adhesion layer, a hue adjustment layer, and a refractive index adjustment layer, to the surface of this optical film.

Hereinafter, the present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples.

(Example 1)
“Neoprim C6A20” (γ-butyrolactone solvent, 22 mass%) manufactured by Mitsubishi Gas Chemical Company, which is a polyimide polymer, a solution in which silica particles having a solid content concentration of 30 mass% are dispersed in γ-butyrolactone, an alkoxysilane having an amino group A dimethylacetamide solution and water were mixed and stirred for 30 minutes. Here, the mass ratio of silica and polyimide is 30:70, the amount of alkoxysilane having an amino group is 1.67 parts by mass with respect to 100 parts by mass of silica and polyimide, and water is 100 parts by mass of silica and polyimide. It was 10 mass parts with respect to this.

The obtained mixed solution was applied to a glass substrate and heated at 50 ° C. for 30 minutes and at 140 ° C. for 10 minutes to dry the solvent. Thereafter, the film was peeled off from the glass substrate, a metal frame was attached, and the film was heated at 210 ° C. for 1 hour to obtain a transparent polyimide film original fabric having a thickness of 50 μm. The refractive index of the original film was 1.57.

The film was cut and the edge was modified by performing CO ₂ laser irradiation under the following conditions.
Apparatus: ML-Z9510T manufactured by Keyence Corporation
Wavelength: 9.3 μm
Output: 80%
Processing speed: 150 mm / sec Processing size: 5 cm x 5 cm

(Comparative Example 1)
A polyimide-based polymer film original fabric was obtained in the same manner as in Example 1. A rectangular (5 cm × 5 cm) region was cut out from the obtained film original with a shear blade to obtain an optical film.

<XPS measurement>
About the edge part of the optical film obtained by the Example and the comparative example, the X-ray photoelectron spectroscopy (XPS) measurement was performed in the following steps 1 and 2. The XPS measurement conditions are as follows.
Equipment: Quantera SXM (manufactured by ULVAC PHI)
X-ray: AlKα ray (1486.6 eV)
X-ray spot diameter: 50 μm
Neutralization conditions: neutralization electron (1 eV), low-speed Ar ion (10 eV)

(Step 1)
Attaching the optical film to a metal block, fixing the film end face upward, irradiating the film end face with X-rays from above (vertical direction), detecting photoelectrons from the 45 ° direction, and evaluating the film end face did. F / C was calculated from the area of the C1s and F1s peaks of the obtained XPS spectrum. F / C was calculated by measuring three points spaced at regular intervals on the end face of one side of the film, and the average value thereof was taken as F / C of the end face. Similarly, F / O was determined.

(Step 2)
Next, the part 1 mm away from the film end face was cut with a razor (PERSONNA, Single Edge, stainless steel, 3-Facet .009 ”/. 23 mm). Steps for cutting with a razor The XPS measurement was performed under the same conditions as 1, and the F / C of the film cross section (inside the film) was obtained.

The XPS measurement was first performed on two opposite end portions (referred to as a first end portion and a second end portion, respectively) of the optical films obtained in Examples and Comparative Examples. The results are shown in Table 1. In addition, about the optical film obtained by the Example and the comparative example, it was an XPS measurement result equivalent to a 1st end part and a 2nd end part about 4 sides.

<Evaluation of crack resistance>
The optical film of 5 cm × 5 cm obtained in Examples and Comparative Examples was wound around a 5 mm diameter SUS rod and stored in an environment of 85 ° C. and 85% RH for 15 hours. Winding was performed in a direction in which the two sides of the first end and the second end were wound perpendicularly to the SUS rod. The first end and the second end of the optical film after storage were observed, and the generated cracks were confirmed with an optical microscope. The number of cracks with a length exceeding 100 μm per 5 cm width at the first end and the second end was counted, and the average number of cracks at both ends was determined. The results are shown in Table 1.

From the results shown in Table 1, it can be seen that the end face of the film of Example 1 is oxidized with increased oxygen atoms. Further, as is clear from the results shown in Table 1, according to the optical film of Example 1 having a larger F / C value at the end face than inside the film, the film was placed in a high temperature and high humidity environment in a deformed state. It was confirmed that cracks were hardly generated at the ends even when stored. Moreover, according to the optical film of Example 1 whose end face has a larger F / O value than the inside of the film, even when stored in a high temperature and high humidity environment in a deformed state, cracks are unlikely to occur at the end. It was confirmed.

10 ... Optical film, 100 ... Flexible display.

Claims

An optical film containing a polyimide polymer containing a fluorine atom in the molecule,
The atomic ratio (F / C) of fluorine atoms to carbon atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film was measured by X-ray photoelectron spectroscopy in a cross section cut 1 mm inside from the end face of the optical film. An optical film having a larger atomic ratio (F / C) of fluorine atoms to carbon atoms to be measured.
The atomic ratio (F E / C E ) of fluorine atoms to carbon atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film, and X-ray photoelectron spectroscopy at a cross section cut 1 mm inside from the end face of the optical film The ratio (F E / C E ) / (F C / C C ) to the atomic ratio (F C / C C ) of fluorine atoms to carbon atoms measured by the method is 1.1 to 10. The optical film described in 1.
An optical film containing a polyimide polymer containing a fluorine atom in the molecule,
The atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film is determined by X-ray photoelectron spectroscopy in a cross section cut 1 mm inside from the end face of the optical film. An optical film having a larger atomic ratio (F / O) of fluorine atoms to oxygen atoms to be measured.
The atomic ratio (F E / O E ) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film, and X-ray photoelectron spectroscopy at a cross section taken 1 mm inside from the end face of the optical film The ratio (F E / O E ) / (F C / O C ) to the atomic ratio of fluorine atoms to oxygen atoms (F C / O C ) measured by the method is 1.1 to 10. The optical film described in 1.
The optical film according to any one of claims 1 to 4, further comprising silica particles.
A method for producing an optical film containing a polyimide polymer containing a fluorine atom in a molecule,
By oxidizing the end face, the atomic ratio (F / C) of fluorine atoms to carbon atoms measured by X-ray photoelectron spectroscopy on the end face of the optical film was cut 1 mm inside from the end face of the optical film. The manufacturing method of an optical film which has the process made larger than the atomic ratio (F / C) of the fluorine atom with respect to the carbon atom measured by a X-ray photoelectron spectroscopy in a cross section.
A method for producing an optical film containing a polyimide polymer containing a fluorine atom in a molecule,
By forming the end face of the optical film by cutting the film original by laser irradiation, the atomic ratio (F / F) of fluorine atoms measured by X-ray photoelectron spectroscopy on the end face of the optical film is measured. An optical film having a step of making C) larger than an atomic ratio (F / C) of a fluorine atom to a carbon atom measured by X-ray photoelectron spectroscopy in a cross section obtained by cutting 1 mm inside from the end face of the optical film Manufacturing method.
A method for producing an optical film containing a polyimide polymer containing a fluorine atom in a molecule,
By oxidizing the end face, the atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film was cut 1 mm inside from the end face of the optical film. The manufacturing method of an optical film which has a process made larger than the atomic ratio (F / O) with respect to the oxygen atom of the fluorine atom measured by a X-ray photoelectron spectroscopy in a cross section.
A method for producing an optical film containing a polyimide polymer containing a fluorine atom in a molecule,
By forming the end face of the optical film by cutting the film original by laser irradiation, the atomic ratio (F / F) of fluorine atoms measured by X-ray photoelectron spectroscopy at the end face of the optical film is measured. An optical film having a step of making O) larger than an atomic ratio (F / O) of fluorine atoms to oxygen atoms measured by X-ray photoelectron spectroscopy in a cross section cut 1 mm inside from the end face of the optical film Manufacturing method.
A front plate for a flexible device comprising the optical film according to any one of claims 1 to 5.
A flexible device having a flexible functional layer and the optical film according to any one of claims 1 to 5.