CN112041707B - Optical film, optical laminate, and flexible image display device - Google Patents

Abstract

An object of the present invention is to provide an optical film having excellent visibility when used appropriately as an optical film in an image display device. It is an optical film comprising at least one selected from the group consisting of polyimide, polyamide, and polyamideimide, and satisfies formula (1): 1.1≤transmission b*-reflection (SCE)b*≤ 15...(1) [In formula (1), transmission b* represents b* of light transmitted from the optical film in the L*a*b* colorimetric system, and reflection (SCE) b* represents calculated by SCE method. b*] in the L*a*b* colorimetric system of light reflected by the optical film.

Description

Optical film, optical laminate, and flexible image display device

technical field

The present invention relates to an optical film comprising at least one selected from the group consisting of polyimide, polyamide, and polyamideimide.

Background technique

In recent years, optical films containing polyimide-based resins have been used as functional films for imparting functions to image display devices such as televisions, personal computers, smartphones, tablet computers, and electronic paper. Since the user of such an image display device directly visually recognizes the displayed image through the optical film used in the display device, the optical film is required to have very high visibility. For example, Patent Document 1 describes an optical film containing a polyimide resin and silica particles.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2009-215412

SUMMARY OF THE INVENTION

The problem to be solved by the invention

However, according to the study of the inventors of the present application, it has been found that even if such an optical film containing a polyimide-based resin is applied to an image display device, sufficient visibility may not be obtained.

Therefore, an object of the present invention is to provide an optical film having excellent visibility, an optical laminate including the optical film, and a flexible image display device.

means of solving problems

In order to solve the above-mentioned problems, the inventors of the present application have conducted intensive studies, and as a result found that, in an optical film containing at least one selected from the group consisting of polyimide, polyamide, and polyamideimide, the By adjusting transmission b*-reflection (SCE) b* within a predetermined range, the above-mentioned problems can be solved, and the present invention has been completed. That is, the present invention includes the following aspects.

[1] An optical film comprising at least one selected from the group consisting of polyimide, polyamide, and polyamideimide, and satisfying Formula (1):

1.1≤transmission b*-reflection (SCE)b*≤15…(1)

[In the formula (1), transmission b* represents b* of light transmitted from the optical film in the L*a*b* colorimetric system, and reflection (SCE) b* represents the optical film obtained by the SCE method The b* of reflected light in the L*a*b* colorimetric system.

[2] The optical film according to [1], which further satisfies the formula (2):

Transmission b*-reflection (SCI)b*≤4.5...(2)

[In the formula (2), transmission b* represents b* in the L*a*b* colorimetric system of light transmitted through the optical film, and reflection (SCI) b* represents the optical film obtained by the SCI method The b*] of reflected light in the L*a*b* colorimetric system.

[3] The optical film according to [1] or [2], which has a haze of 1% or less and a total light transmittance Tt of 85% or more.

[4] The optical film according to any one of [1] to [3], which further contains silica particles.

[5] The optical film according to [4], wherein the silica particles are silica particles obtained by solvent-substituting a water-soluble alcohol-dispersed silica sol.

[6] The optical film according to any one of [1] to [5], which further contains an ultraviolet absorber.

[7] The optical film according to any one of [1] to [6], which further contains silica particles,

The three-dimensional distance Ra determined by the Hansen dissolving sphere method satisfies the formula (3):

Ra≤8.0...(3)

[In formula (3), Ra represents the three-dimensional distance between the above-mentioned silica particles and at least one selected from the group consisting of the above-mentioned polyimide, the above-mentioned polyamide, and the above-mentioned polyamideimide in the solubility parameter space ].

[8] An optical laminate comprising: the optical film according to any one of [1] to [7]; and a hard coat layer on at least one surface of the optical film.

[9] A flexible image display device including the optical laminate according to [8].

[10] The flexible image display device according to [9], further comprising a polarizing plate.

[11] The flexible image display device according to [9] or [10], further including a touch sensor.

effect of invention

According to the present invention, when used as an optical film in an image display device, an optical film having excellent visibility can be provided. Moreover, according to this invention, the optical laminated body and flexible image display apparatus containing the optical film which have excellent visibility can be provided.

Detailed ways

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

＜Optical film＞

The optical film of the present invention is an optical film containing at least one selected from the group consisting of polyimide, polyamide, and polyamideimide, and satisfies the formula (1):

1.1≤transmission b*-reflection (SCE)b*≤15…(1)

[In the formula (1), transmission b* represents b* of light transmitted from the optical film in the L*a*b* colorimetric system, and reflection (SCE) b* represents the optical film obtained by the SCE method The b*] of reflected light in the L*a*b* colorimetric system.

[1. Formula (1)]

When an optical film satisfies Formula (1), the visibility of an optical film is excellent. From the viewpoint of further improving the visibility of the optical film, the formula (1) is preferably 10 or less, more preferably 8 or less, still more preferably 6 or less, and particularly preferably 4 or less. From the viewpoint of further improving the clarity of the optical film, the numerical value of the formula (1) (transmission b*-reflection (SCE) b*) is preferably 1.3 or more, more preferably 1.4 or more, still more preferably 1.45 or more, and particularly preferably 1.5 and above.

(transmission b*)

The transmission b* of the optical film is the b* of the light transmitted from the optical film in the L*a*b* colorimetric system. In this specification, it refers to the transmission light of the following incident light (white light) in CIE1976L* The b* value in the a*b* colorimetric system, the incident light (white light) is incident light in the range of wavelength 380-780 nm which is incident from the direction perpendicular to the plane of the optical film. The transmission b* is preferably 0.3 or more, more preferably 1.6 or less, and still more preferably 1.5 or less. These plural upper limit values and lower limit values can be arbitrarily combined. The transmission b* of the optical film can be measured using an ultraviolet-visible-near-infrared spectrophotometer, for example, by the method described in the examples.

(Reflection(SCE)b*)

The reflection (SCE) b* of an optical film is b* in the L*a*b* colorimetric system of the light reflected by the optical film obtained by the SCE (Specular Component Excluded: Specular Component Excluded) method, and this specification , refers to the b* value in the CIE1976L*a*b* colorimetric system of the diffusely reflected light excluding the specularly reflected light in the reflected light of the following incident light, the incident light is from the optical film Incident light within a wavelength range of 380 to 780 nm that is incident in a direction inclined by a predetermined angle to the vertical direction of the plane. The reflection (SCE) b* is preferably -2.5 or more, preferably -2.4 or more, and more preferably -2.3 or more. The reflection (SCE) b* is preferably -0.02 or less, preferably -0.05 or less, more preferably -0.07 or less, and particularly preferably -0.1 or less. These plural upper limit values and lower limit values can be arbitrarily combined. The reflection (SCE) b* of the optical film can be measured using a spectrophotometer, for example, by the method described in the Examples.

As means for adjusting the numerical value of the formula (1) within a predetermined numerical range, for example, a means for reducing the interaction between white light and components in the optical film is exemplified. As means for reducing this interaction, for example, the film thickness of the optical film, the addition of additives (more specifically, silica particles, ultraviolet absorbers, brighteners, etc.), and the properties of additives ( More specifically, means for adjusting particle size, surface modification, and content within a predetermined range. Among them, when the particle size, surface modification, and content of the silica particles are adjusted within the predetermined ranges, the silica particles are less likely to agglomerate in the optical film and can exist in the form of primary particles, so that the silica particles are easily contained in the optical film. Disperse uniformly in the optical film. Furthermore, interaction with white light due to the uneven shape on the surface of the optical film is reduced, and in the optical film, the interaction of the aggregates with white light is reduced, so it is considered that it contributes to the visibility.

[2. Formula (2)]

The optical film of the present invention preferably satisfies the formula (2):

Transmission b*-reflection (SCI)b*≤4.5...(2)

[In the formula (2), the transmission b* has the same meaning as the formula (1), and the reflection (SCI) b* represents the light reflected by the above-mentioned optical film obtained by the SCI method in the L*a*b* colorimetric system b*].

When the optical film satisfies the formula (2), the visibility of the optical film is further improved. From the viewpoint of further improving the visibility of the optical film, the numerical value (transmission b*-reflection (SCI) b*) of the formula (2) is preferably 4.1 or less, more preferably 4.0 or less, and further preferably 3.9 or less.

(Reflection (SCI)b*)

The reflection (SCI) b* of the optical film is the b* in the L*a*b* color system of the light reflected by the above-mentioned optical film obtained by the SCI (Specular Component Included: Specular Component Included) method, and this specification , refers to the b* value in the CIE1976L*a*b* colorimetric system of the reflected light (including the specularly reflected light) relative to the following incident light, which is measured from the plane of the optical film Incident light within the wavelength range of 380 to 780 nm that is incident in a direction whose vertical direction is inclined by a predetermined angle. The reflection (SCI) b* is preferably -2.9 or more, more preferably -2.7 or more, and further preferably -2.5 or more. The reflection (SCI) b* is preferably -1.2 or less, more preferably -1.4 or less, and further preferably -1.6 or less. These plural upper limit values and lower limit values can be arbitrarily combined. The reflection (SCI) b* of the optical film can be measured using a spectrophotometer, for example, by the method described in the Examples. As means for adjusting the numerical value of the formula (2) within the predetermined numerical range, for example, a means for adjusting the numerical value of the above-mentioned formula (1) within the predetermined numerical range is exemplified.

[3. Haze]

From the viewpoint of further improving the visibility of the optical film, the haze of the optical film of the present invention is preferably 1% or less, more preferably 0.8% or less, still more preferably 0.5% or less, and particularly preferably 0.3% or less. The haze of an optical film can be measured in accordance with JIS K 7136:2000, and can be measured, for example, by the method described in Examples. The haze of the optical film represents the degree of dispersibility of the additive in the optical film, and therefore when the haze of the optical film is within the above range, the visibility of the optical film is excellent.

[4. Total light transmittance]

The total light transmittance of the optical film of the present invention is preferably 85% or more, more preferably 87% or more, and further preferably 89% or more. The total light transmittance of an optical film can be measured according to JIS K7361-1:1997, and can be measured, for example, by the method described in Examples. When the total light transmittance of the optical film is within the above-mentioned numerical range, sufficient visibility can be ensured when incorporated into an image display device. In addition, when the total light transmittance of the optical film is within the above-mentioned numerical range, a constant luminance can be easily ensured, so that, for example, the luminous intensity of the display element and the like can be suppressed, and the power consumption of the image display device can be reduced.

[5. Yellow Index (YI)]

The yellow index of the optical film of this invention becomes like this. Preferably it is 3.0 or less, More preferably, it is 2.7 or less, More preferably, it is 2.5 or less. The yellowness index of an optical film can be measured according to JIS K 7373:2006, and can be measured, for example, by the method described in Examples.

[6. Film thickness]

The film thickness of the optical film of the present invention is preferably 10 μm or more, more preferably 20 μm or more, and further preferably 25 μm or more. In addition, the film thickness is preferably 120 μm or less, more preferably 100 μm or less, still more preferably 90 μm or less, and particularly preferably 85 μm or less. When the film thickness is 30 μm or more, it is advantageous from the viewpoint of protecting the inside when the optical film is used as a device, and when the film thickness is 120 μm or less, it is advantageous from the viewpoints of folding endurance, cost, transparency, and the like. The film thickness of the optical film can be measured, for example, by the method described in the examples.

[7. Solubility parameter]

The inventors of the present application have found that the composition in the optical film causes aggregation or the like due to poor dispersion, which reduces the visibility in the wide-angle direction. absorbers, silica particles, and whitening agents, etc.) and a medium (eg, a resin, more specifically, at least one resin selected from the group consisting of polyimide, polyamide, and polyamideimide) As an index for evaluating the affinity of , the Hansen Solubility Parameter (Hansen Solubility Parameter; hereinafter, sometimes abbreviated as HSP) is introduced. As a result of intensive research, the inventors of the present application have derived the following formulas (3) to (5). That is, from the viewpoint of further improving the visibility in the wide-angle direction (particularly, from the viewpoint of suppressing the occurrence of the inconvenience of whitishness in black display), the optical film of the present invention preferably satisfies the formula (3) related to HSP:

Ra≤8.0...(3)

[In the formula (3), Ra represents the three-dimensional distance between the above-mentioned solute and the above-mentioned medium in the HSP space].

In addition, from the viewpoint of further improving the visibility in the wide-angle direction, it is more preferable that the optical film of the present invention satisfies the formula (4) or the formula (5) related to HSP in addition to the formula (3):

Δδ _t ≤2.0……(4)

[In the formula (4), Δδ _t represents the difference in the total δ _t of the dispersion term, polar term, and hydrogen bond term of HSP between the above-mentioned solute and the above-mentioned medium]

Δδ _p ≤4.5...(5)

[In the formula (5), Δδ _p represents the difference between the above-mentioned solute and the above-mentioned medium of HSP polarity term δ _p ].

Moreover, it is more preferable that the optical film of this invention satisfy|fills all of Formula (3) - Formula (5) from a viewpoint of further improving the visibility in a wide-angle direction.

(7-1. Calculation method of HSP value)

The HSP value was calculated using the Hansen Solubility Sphere method. Hereinafter, the details will be described. The target composition (the above-mentioned solute and the above-mentioned medium) was dissolved or dispersed in a solvent with a known HSP value, and the solubility or dispersibility of the composition in a specific solvent was evaluated. The evaluation of solubility and dispersibility was performed by visually judging whether or not the target composition was dissolved in the solvent and whether it was dispersed in the solvent, respectively. This evaluation was performed for various solvents. As for the kind of the solvent, it is preferable to use a solvent whose δ _t is greatly different, and more specifically, it is preferably 10 or more, more preferably 15 or more, and still more preferably 18 or more. Next, the obtained evaluation results of solubility or dispersibility are plotted in a three-dimensional space (HSP space) including the dispersion term δ _d of HSP, the polar term δ _p , and the hydrogen bond term δ _h . A sphere (Hansen sphere) having the smallest radius is prepared by including the solvent for dissolving or dispersing the target composition on the inside, and the solvent for not dissolving or dispersing the target composition on the outside. The center coordinates (δ _d , δ _p , δ _h ) of the obtained Hansen sphere are taken as the HSP of the object composition.

(7-2. Calculation method of δ _t , Δδ _t , Δδ _p and Ra)

Calculate the HSP value (δ _d1 , δ _p1 , δ _h1 : component 1) of two components in the optical film, for example, when resin is used as component 1 and silica is used as component 2, using the calculation method of 7-1. δ _d2 , δ _p2 , δ _h2 : HSP values of component 2).

The total δ _t of the dispersion term, the polar term, and the hydrogen bond term of HSP, and the difference Δδ _t of the total between component 1 and component 2 are calculated using equations (6) and (7), respectively. The resulting delta _t corresponds to Hildebrand's HSP.

δ _t ² =δ _d ² +δ _p ² +δ _h ² ......(6)

Δδ _t = |δ _t2 -δ _t1 |...(7)

From the viewpoint of further improving the visibility in the wide-angle direction, _Δδt is preferably 3.5 or less, more preferably 3.0 or less, still more preferably 2.0 or less, still more preferably 1.0 or less, and particularly preferably 0.5 or less.

The difference _Δδp in the polarity term of the HSP between the component 1 and the component 2 is calculated using the formula (8).

Δδ _p = |δ _p2 -δ _p1 |...(8)

From the viewpoint of further improving the visibility in the wide-angle direction, Δδ _p is preferably 4.5 or less, more preferably 3.5 or less, still more preferably 3.0 or less, still more preferably 2.0 or less, and particularly preferably 1.0 or less.

The three-dimensional distance Ra (>0) between the component 1 and the component 2 in the HSP space is calculated using the formula (9).

Ra ² =4(δ _d2 -δ _d1 ) ² +(δ _p2 -δ _p1 ) ² +(δ _h2 -δ _h1 ) ² ......(9)

The smaller the Ra value, the better the affinity between the component 1 and the component 2 is. From the viewpoint of further improving the visibility in the wide-angle direction, the Ra value is preferably 8.0 or less, more preferably 7.0 or less, still more preferably 6.0 or less, still more preferably 5.5 or less, and particularly preferably 5.0 or less.

[8. Polyimide, polyamide, polyamideimide]

The optical film of the present invention contains at least one resin selected from the group consisting of a polyimide-based resin and a polyamide-based resin. The term "polyimide-based resin" means a polymer (hereinafter, sometimes referred to as polyimide) containing a repeating structural unit containing an imide group, and a repeating structure containing both an imide group and an amide group. At least one polymer in the group consisting of a polymer of a structural unit (hereinafter, it may be described as polyamideimide). In addition, the polyamide-based resin means a polymer containing a repeating structural unit including an amide group.

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

[Chemical formula 1]

The polyimide-based resin may contain at least one selected from the group consisting of repeating structural units represented by formula (11), formula (12), and formula (13) within a range that does not impair various physical properties of the optical film.

[Chemical formula 2]

In formula (10) and formula (11), G and G ¹ are each independently a tetravalent organic group, preferably an organic group which may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group. As G and G ¹ , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula ( 28) or a group represented by formula (29) and a tetravalent chain hydrocarbon group having 6 or less carbon atoms. Among them, Formula (20), Formula (21), Formula (22), Formula (23), Formula (24), Formula (25), Formula (25), Formula (25), Formula (25), Formula (22), Formula (23), Formula (24), Formula (25), Formula (25), Formula (25), Formula (25), Formula (21), Formula (22) (26) or a group represented by formula (27).

[Chemical formula 3]

In formulas (20) to (29),

* denotes chemical bond,

Z represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -Ar -, -SO ₂ -, -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or - Ar-SO ₂ -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms which may be substituted by a fluorine atom, and a specific example thereof includes a phenylene group.

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

In formula (13), G ³ is a divalent organic group, preferably an organic group which may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group. As G ³ , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) can be exemplified Or a group in which two non-adjacent hydrogen atoms are substituted in the chemical bond of the group represented by the formula (29), and a chain hydrocarbon group having 6 or less carbon atoms.

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

[Chemical formula 4]

In formulas (30) to (38),

* denotes chemical bond,

Z ¹ , Z ² and Z ³ each independently represent 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-.

As an example, Z ¹ and Z ³ are -O-, and Z ² is -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ - or -SO ₂ -. It is preferable that the bonding positions of Z ¹ and Z ² with respect to each ring, and the bonding positions of Z ² and Z ³ with respect to each ring, respectively, are meta-position or para-position with respect to each ring.

The polyimide-based resin is preferably a polyamideimide having at least the repeating structural unit represented by the formula (10) and the repeating structural unit represented by the formula (13) from the viewpoint of easily improving the visibility. In addition, the polyamide-based resin preferably has at least a repeating structural unit represented by the formula (13).

In one embodiment of the present invention, the polyimide-based resin is made of a diamine and a tetracarboxylic acid compound (an acid chloride compound, a tetracarboxylic acid compound analog such as a tetracarboxylic dianhydride), and a dicarboxylic acid compound ( A condensed polymer obtained by reacting (polycondensation) with a dicarboxylic acid compound analog such as an acid chloride compound), a tricarboxylic acid compound (a tricarboxylic acid compound analog such as an acid chloride compound and a tricarboxylic anhydride) or the like. The repeating structural unit represented by the formula (10) or the formula (11) is usually derived from a diamine and a tetracarboxylic acid compound. The repeating structural unit represented by the formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by the formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

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

Examples of the tetracarboxylic acid compound include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydrides; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydrides. The tetracarboxylic acid compound may be used alone or in combination of two or more. The tetracarboxylic acid compound may be an analog of a tetracarboxylic acid compound such as an acid chloride compound in addition to the dianhydride.

Specific examples of the aromatic tetracarboxylic dianhydride include 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-diphenyl Ketonetetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3, 3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2, 2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene ) Diphthalic dianhydride (4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, 6FDA), 1,2-bis(2,3-dicarboxyphenyl)ethanedianhydride, 1,1-bis(2 ,3-Dicarboxyphenyl)ethanedianhydride, 1,2-bis(3,4-dicarboxyphenyl)ethanedianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane Dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride and 4,4'-(p-phenylenedioxy) Diphthalic dianhydride and 4,4'-(m-phenylenedioxy) diphthalic dianhydride. These may be used alone or in combination of two or more.

Cyclic or acyclic aliphatic tetracarboxylic dianhydride is mentioned as aliphatic tetracarboxylic dianhydride. The cycloaliphatic tetracarboxylic dianhydride refers to 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, 1,2,3,4-cyclopentanetetracarboxylic dianhydride and other cycloalkane tetracarboxylic dianhydrides, bicyclo[2.2.2]octane-7- Alkene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride and their positional isomers. These may 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. It may be used alone or in combination of two or more. Moreover, a cycloaliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride can be used in combination.

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

As the tricarboxylic acid compound, aromatic tricarboxylic acid, aliphatic tricarboxylic acid, and acid chloride compounds similar to these, acid anhydrides, etc. may be mentioned, and two or more of them may be used in combination.

Specific examples include anhydride of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; phthalic anhydride and benzoic acid via a single bond, -CH ₂ A compound in which -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ - or phenylene are connected.

Examples of the dicarboxylic acid compound include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and acid chloride compounds similar to these, acid anhydrides, and the like, and two or more of them may be used in combination. Specific examples of these include terephthaloyl dichloride (TPC); isophthaloyl dichloride; naphthaloyl dichloride; 4,4'-biphthaloyl dichloride; Phthaloyl dichloride; 4,4'-oxybis(benzoyl chloride) (OBBC, 4,4'-oxybis(benzoyl chloride)); dicarboxylic acid compound of chain hydrocarbon with 8 or less carbon atoms and a compound in which two benzoic acids are connected via a single bond, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ - or phenylene.

As a diamine, aliphatic diamine, aromatic diamine, or these mixtures are mentioned, for example. In addition, in this embodiment, "aromatic diamine" means the diamine in which an amino group couple|bonded directly with an aromatic ring, and a part of the structure may contain an aliphatic group or another substituent. The aromatic ring may be a single ring or a condensed ring, and examples thereof include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among these, the aromatic ring is preferably a benzene ring. In addition, the "aliphatic diamine" means a diamine in which an amino group is directly bonded to an aliphatic group, and a part of the structure may contain an aromatic ring or other substituents.

Examples of aliphatic diamines include acyclic aliphatic diamines such as 1,6-hexanediamine, 1,3-bis(aminomethyl)cyclohexane, and 1,4-bis(aminomethyl) Cycloaliphatic diamines such as cyclohexane, norbornanediamine, and 4,4'-diaminodicyclohexylmethane, etc. These may be used alone or in combination of two or more.

Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,5-diaminonaphthalene, Aromatic diamines having one aromatic ring such as 6-diaminonaphthalene; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl base ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone , 3,3'-diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-diamino Diphenylsulfone, 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(tris Fluoromethyl)benzidine (2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB)), 4,4'-bis(4-aminophenoxy)biphenyl , 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 9,9-bis(4-aminophenyl)fluorene , 9,9-bis(4-amino-3-methylphenyl)fluorene, 9,9-bis(4-amino-3-chlorophenyl)fluorene, 9,9-bis(4-amino-3- Aromatic diamines having two or more aromatic rings, such as fluorophenyl) fluorene. These may be used alone or in combination of two or more.

From the viewpoint of high transparency and low colorability, among the above-mentioned diamines, it is preferable to use at least one selected from the group consisting of aromatic diamines having a biphenyl structure. It is further preferable to use the group selected from 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4'-bis(4-aminophenoxy)biphenyl. One or more of the group consisting of 4'-diaminodiphenyl ether, and 2,2'-bis(trifluoromethyl)benzidine is more preferably used.

The polyimide-based resin can be obtained by mixing the above-mentioned raw materials such as diamine, tetracarboxylic acid compound, tricarboxylic acid compound, and dicarboxylic acid compound by a conventional method, such as stirring, etc. The obtained intermediate is imidized in the presence of an imidization catalyst and, if necessary, a dehydrating agent. The polyamide-based resin can be obtained by mixing the above-mentioned diamines, dicarboxylic acid compounds, and other raw materials by a conventional method, for example, by a method such as stirring.

等脂环式胺(单环式)；氮杂双环[2.2.1]庚烷、氮杂双环[3.2.1]辛烷、氮杂双环[2.2.2]辛烷、及氮杂双环[3.2.2]壬烷等脂环式胺(多环式)；以及2-甲基吡啶、3-甲基吡啶、4-甲基吡啶、2-乙基吡啶、3-乙基吡啶、4-乙基吡啶、2,4-二甲基吡啶、2,4,6-三甲基吡啶、3,4-环戊烯并吡啶、5,6,7,8-四氢异喹啉、及异喹啉等芳香族胺。The imidization catalyst used in the imidization step is not particularly limited, and examples thereof include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; N-ethyl Piperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine

Alicyclic amines (monocyclic); azabicyclo[2.2.1]heptane, azabicyclo[3.2.1]octane, azabicyclo[2.2.2]octane, and azabicyclo[3.2 .2] Alicyclic amines such as nonane (polycyclic); and 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine pyridine, 2,4-lutidine, 2,4,6-collidine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline Aromatic amines such as linoline.

Although it does not specifically limit as a dehydrating agent used in an imidization process, For example, acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, isovaleric anhydride, etc. are mentioned.

In the mixing of each raw material and the imidization step, the reaction temperature is not particularly limited, but is, for example, 15 to 350°C, preferably 20 to 100°C. The reaction time is also not particularly limited, but is, for example, about 10 minutes to 10 hours. The reaction can be carried out in an inert atmosphere or under reduced pressure as necessary. In addition, the reaction can be carried out in a solvent, and examples of the solvent include those exemplified as the solvent usable for the preparation of varnishes. After the reaction, the polyimide-based resin or the polyamide-based resin is purified. As a purification method, for example, a method of adding a poor solvent to the reaction liquid, precipitating a resin by a reprecipitation method, drying and taking out a precipitate, washing the precipitate with a solvent such as methanol as necessary, and allowing its dry.

In addition, the manufacturing method of Unexamined-Japanese-Patent No. 2006-199945 or Unexamined-Japanese-Patent No. 2008-163107 can be referred to manufacture of a polyimide-type resin, for example. In addition, a commercial item can also be used for the polyimide-based resin, and specific examples thereof include Neopulim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd., KPI-MX300F manufactured by Kawamura Sangyo Co., Ltd., and the like .

The weight average molecular weight of the polyimide-based resin or polyamide-based resin is preferably 200,000 or more, more preferably 250,000 or more, still more preferably 300,000 or more, preferably 600,000 or less, and more preferably 500,000 or less. The higher the weight average molecular weight of the polyimide-based resin or the polyamide-based resin, the more likely it is to exhibit high bending resistance at the time of film formation. Therefore, from the viewpoint of improving the bending resistance of the optical film, the weight average molecular weight is preferably equal to or more than the above-mentioned lower limit. On the other hand, as the weight average molecular weight of the polyimide-based resin or the polyamide-based resin is smaller, the viscosity of the varnish tends to be easily lowered and the processability tends to be improved. Moreover, there exists a tendency for the stretchability of a polyimide-type resin or a polyamide-type resin to improve easily. Therefore, from the viewpoint of workability and stretchability, the weight average molecular weight is preferably not more than the above-mentioned upper limit. In addition, in this application, the weight average molecular weight can be calculated|required by performing gel permeation chromatography (GPC) measurement and calculated|required by standard polystyrene conversion, for example, it can calculate by the method described in an Example.

The imidization rate of the polyimide-based resin is preferably 95 to 100%, more preferably 97 to 100%, still more preferably 98 to 100%, and particularly preferably 100%. From the viewpoint of the stability of the varnish and the mechanical properties of the optical film obtained, the imidization ratio is preferably equal to or more than the above-mentioned lower limit. In addition, the imidization rate can be calculated|required by IR method, NMR method, etc.. From the viewpoints described above, the imidization ratio of the polyimide-based resin contained in the varnish is preferably within the above-described range.

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 may contain, for example, halogen atoms such as fluorine atoms which can be introduced by the above-mentioned fluorine-containing substituent or the like. When the polyimide-based resin or the polyamide-based resin contains a halogen atom, the elastic modulus of the optical film tends to be increased, and the yellowness index (YI value) tends to decrease. When the elastic modulus of the optical film is high, the occurrence of flaws, wrinkles, etc. in the film can be easily suppressed, and when the yellow index of the optical film is low, the transparency of the film can be easily improved. The halogen atom is preferably a fluorine atom. As a fluorine-containing substituent which is preferable in order to make a polyimide-type resin or a polyamide-type resin contain a fluorine atom, a fluorine group and a trifluoromethyl group are mentioned, for example.

The content of halogen atoms in the polyimide-based resin or polyamide-based resin is preferably 1 to 40 mass %, more preferably 5 to 40 mass % based on the mass of the polyimide-based resin or polyamide-based resin , more preferably 5 to 30 mass %. When the content of halogen atoms is 1 mass % or more, the elastic modulus at the time of film formation is further increased, the water absorption rate is reduced, the yellowness index (YI value) is further reduced, and the transparency is further improved. When the content of halogen atoms exceeds 40% by mass, synthesis may become difficult.

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

[9. Additives]

The optical film of the present invention may further contain additives. Examples of such additives include fillers (more specifically, silica particles, etc.), ultraviolet absorbers, brighteners, silica dispersants, antioxidants, pH adjusters, and leveling agents.

(Silica particles)

The optical film of the present invention may further contain silica particles as an additive. The content of the silica particles is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on the total mass of the optical film. Moreover, based on the total mass of this optical film, content of a silica particle becomes like this. Preferably it is 60 mass % or less, More preferably, it is 50 mass % or less, More preferably, it is 45 mass % or less. In addition, regarding the content of the silica particles, an arbitrary lower limit value and an upper limit value may be selected and combined from these upper limit value and lower limit value. When the content of the silica particles is within the numerical range of the upper limit and/or the lower limit, in the optical film of the present invention, the silica particles tend to be less likely to agglomerate and to be uniformly dispersed in the state of primary particles. The fall of the visibility of the optical film of this invention can be suppressed.

The particle diameter of the silica particles is preferably 1 nm or more, more preferably 3 nm or more, still more preferably 5 nm or more, particularly preferably 8 nm or more, preferably 30 nm or less, more preferably 28 nm or less, and still more preferably 25 nm or less. Regarding the particle diameter of the silica particles, an arbitrary lower limit value and an upper limit value can be selected and combined from these upper limit value and lower limit value. When the content of the silica particles is within the numerical range of the upper limit and/or the lower limit, the optical film of the present invention is less likely to interact with light of a specific wavelength in white light, so that it is possible to suppress the effect of the present invention. Decrease in the visibility of the optical film. In the present specification, the particle diameter of the silica particles means the average primary particle diameter. The particle diameter of the silica particles in the optical film can be measured by photographing using a transmission electron microscope (TEM). The particle diameter of the silica particle before producing an optical film (for example, before adding to a varnish) can be measured with a laser diffraction particle size distribution analyzer. The method for measuring the particle diameter of the silica particles is described in detail in the examples.

As a form of a silica particle, the silica sol obtained by disperse|distributing a silica particle in an organic solvent etc., and the silica powder prepared by the gas phase method are mentioned, for example. Among these, from the viewpoint of workability, silica sol is preferable.

The silica particles may be surface-treated, for example, silica particles obtained by substituting a solvent (more specifically, γ-butyrolactone, etc.) with a water-soluble alcohol-dispersed silica sol. The water-soluble alcohol is an alcohol having 3 or less carbon atoms per hydroxyl group in one molecule of the water-soluble alcohol, and examples thereof include methanol, ethanol, 1-propanol, and 2-propanol. Although it also depends on the compatibility of the silica particles with the types of polyimide-based resins and polyamide-based resins, in general, when the silica particles are surface-treated, they will not be compatible with the polyimide contained in the optical film. Since the affinity of the amine-based resin and the polyamide-based resin is improved, and the dispersibility of the silica particles tends to be improved, the decrease in the visibility of the present invention can be suppressed.

(UV absorber)

The optical film of the present invention may further contain an ultraviolet absorber. For example, a triazine type ultraviolet absorber, a benzophenone type ultraviolet absorber, a benzotriazole type ultraviolet absorber, a benzoate type ultraviolet absorber, a cyanoacrylate type ultraviolet absorber, etc. are mentioned. These may be used alone or in combination of two or more. Preferable commercially available ultraviolet absorbers include, for example, Sumisorb (registered trademark) 340 manufactured by Sumika Chemtex Co., Ltd., Adekastab (registered trademark) LA-31 manufactured by ADEKA Corporation, and BASF JAPAN Co., Ltd. TINUVIN (registered trademark) 1577 and so on. Based on the mass of the optical film of the present invention, the content of the ultraviolet absorber is preferably 1 phr or more and 10 phr or less, and more preferably 3 phr or more and 6 phr or less.

(brightener)

The optical film of the present invention may further contain a whitening agent. Regarding the whitening agent, for example, when an additive other than the whitening agent is added, the whitening agent may be added in order to adjust the color tone. As a whitening agent, a monoazo type dye, a triarylmethane type dye, a phthalocyanine type dye, and an anthraquinone type dye are mentioned, for example. Among these, anthraquinone-based dyes are preferred. Preferable commercially available brighteners include, for example, Macrolex (registered trademark) Violet B by Lanxess Corporation, Sumiplast (registered trademark) Violet B by Sumika Chemtex Co., Ltd., and Diaresin by Mitsubishi Chemical Co., Ltd. (registered trademark) BlueG et al. These may be used alone or in combination of two or more. The content of the brightener is preferably 5 ppm or more and 40 ppm or less based on the mass of the optical film of the present invention.

The application of the optical film of this invention is not specifically limited, It can be used for various applications. The optical film of the present invention may be a single layer as described above, or may be a laminate, and the optical film of the present invention may be used as it is, or may be used as a laminate with other films. Since the optical film of the present invention has excellent surface quality, it is useful as an optical film in image display devices and the like.

The optical film of the present invention is useful as a front panel of an image display device, particularly a front panel (window film) of a flexible display. A flexible display has, for example, a flexible functional layer and the above-mentioned polyimide-based film which is laminated on the flexible functional layer and functions as a front panel. That is, the front panel of the flexible display is arranged on the viewing side on the flexible functional layer. The front panel has the function of protecting the flexible functional layer.

[10. Manufacturing method of optical film]

The optical film of the present invention can be produced, for example, by a method including the following steps, but is not particularly limited:

(a) a step of preparing a liquid (hereinafter, sometimes referred to as a varnish) containing the resin and the filler (varnish preparation step);

(b) a step of applying a varnish to a substrate to form a coating film (coating step); and

(c) The process of forming an optical film by drying the applied liquid (coating film) (optical film forming process).

In the varnish preparation step, a varnish is prepared by dissolving the above-mentioned resin in a solvent, adding the above-mentioned filler and other additives as necessary, and stirring and mixing. In addition, when silica is used as a filler, the dispersion liquid of silica sol containing silica may be replaced with a solvent capable of dissolving the above-mentioned resin, for example, a solvent used in the preparation of the following varnish, and The thus obtained silica sol is added to the resin.

The solvent that can be used in the preparation of the varnish is not particularly limited as long as it can dissolve the above-mentioned resin. Examples of the solvent include amide-based solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; lactones such as γ-butyrolactone (GBL) and γ-valerolactone. solvents; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; carbonate-based solvents such as ethylene carbonate and propylene carbonate; and combinations thereof. Among these, an amide-based solvent or a lactone-based solvent is preferable. These solvents may be used alone or in combination of two or more. In addition, the varnish may contain water, an alcohol-based solvent, a ketone-based solvent, an acyclic ester-based solvent, an ether-based solvent, and the like. It is preferable that it is 1-25 mass %, and, as for the solid content concentration of a varnish, it is more preferable that it is 5-20 mass %.

In the coating step, the varnish is coated on the base material by a known coating method to form a coating film. Examples of known coating methods include bar coating, reverse coating, gravure coating, and other roll coating methods, die coating, comma coating, lip coating, spin coating, and screen coating. Coating method, spray coating method, dipping method, spray method, tape casting method, etc.

In the optical film forming step, an optical film can be formed by drying the coating film and peeling off the base material. After peeling, a drying step of drying the optical film may be further performed. Drying of the coating film can usually be performed at a temperature of 50 to 350°C. If necessary, drying of the coating film can be performed in an inert atmosphere or under reduced pressure.

As an example of the base material, when it is a metal type, a SUS plate is mentioned, and when it is a resin type, a PET film, a PEN film, other polyimide type resin or polyamide type resin film, and a cycloolefin type polymer are mentioned. (COP) film, acrylic film, etc. Among them, a PET film, a COP film, etc. are preferable from the viewpoints of being excellent in smoothness and heat resistance, and further, a PET film is more preferable from the viewpoints of adhesiveness to an optical film and cost.

<Optical laminate>

The optical laminate of the present invention has the optical film of the present invention and a hard coat layer (protective film) on at least one of the optical films. The optical laminate may further have an adhesive layer. The optical laminated body of this invention can be comprised, for example by adhering the optical film of this invention and a hard-coat layer via an adhesive layer.

(hard coating)

The thickness of the hard coat layer is not particularly limited, but may be, for example, 2 to 100 μm. When the thickness of the above-mentioned hard coat layer is within the above-mentioned range, sufficient scratch resistance can be ensured, and bending resistance is not easily reduced, and the problem of curling due to curing shrinkage tends to be less likely to occur.

The above-mentioned hard coat layer can be formed by curing a hard coat layer composition containing a reactive material capable of forming a cross-linked structure by active energy ray irradiation or application of thermal energy, and is preferably obtained by active energy ray irradiation. Active energy rays are defined as energy rays capable of decomposing active species-generating compounds to generate active species, and examples thereof include visible light, ultraviolet rays, infrared rays, X-rays, alpha rays, beta rays, gamma rays, and electron beams, and preferably include out UV rays. The said hard-coat composition contains the polymer of at least 1 sort(s) of a radically polymerizable compound and a cationically polymerizable compound.

The said radically polymerizable compound is a compound which has a radically polymerizable group. The radically polymerizable group which the above-mentioned radically polymerizable compound has may be any functional group capable of radical polymerization reaction, and examples thereof include groups including a carbon-carbon unsaturated double bond. A vinyl group, a (meth)acryloyl group, etc. are mentioned. In addition, when the said radically polymerizable compound has two or more radically polymerizable groups, these radically polymerizable groups may be the same, respectively, and may differ. It is preferable that the number of radically polymerizable groups which the said radically polymerizable compound has in 1 molecule is 2 or more from a viewpoint of improving the hardness of a hard-coat layer. As the above-mentioned radically polymerizable compound, a compound having a (meth)acryloyl group is preferably used from the viewpoint of high reactivity, and specifically, a compound having 2 to 6 (methyl) groups in one molecule is used. Acryloyl compound called polyfunctional acrylate monomer, called epoxy (meth)acrylate, urethane (meth)acrylate (urethane (meth)acrylate), polyester (meth)acrylate ) oligomers of acrylates having several (meth)acryloyl groups in the molecule and having a molecular weight of several hundreds to thousands, preferably, epoxy (meth)acrylates, urethanes (methyl) 1 or more of base) acrylate and polyester (meth)acrylate.

The said cationically polymerizable compound is a compound which has a cationically polymerizable group, such as an epoxy group, an oxetanyl group, and a vinyl ether group. From the viewpoint of improving the hardness of the hard coat layer, the number of cationically polymerizable groups contained in one molecule of the cationically polymerizable compound is preferably 2 or more, and more preferably 3 or more.

In addition, among the above-mentioned cationically polymerizable compounds, compounds having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group are preferable. Cyclic ether groups such as an epoxy group and an oxetanyl group are preferable from the viewpoint of small shrinkage accompanying the polymerization reaction. In addition, among the cyclic ether groups, compounds having an epoxy group have the following advantages: compounds with various structures are easily obtained, the durability of the obtained hard coat layer is not adversely affected, and it is easy to control the interaction with radicals. Compatibility of polymeric compounds. In addition, among the cyclic ether groups, the oxetanyl group has the following advantages compared with the epoxy group: the degree of polymerization is easily increased, the formation rate of the network obtained from the cationically polymerizable compound in the obtained hard coat layer is accelerated, and even if In the region where it is mixed with the radically polymerizable compound, unreacted monomers do not remain in the film, and an independent network can be formed; and the like.

Examples of the cationically polymerizable compound having an epoxy group include polyglycidyl ether of a polyhydric alcohol having an alicyclic ring, or a cyclohexene ring containing, Alicyclic epoxy resins obtained by epoxidizing compounds of cyclopentene rings; polyglycidyl ethers of aliphatic polyols or their alkylene oxide adducts, polyglycidyl groups of aliphatic long-chain polyacids Aliphatic epoxy resins such as homopolymers and copolymers of esters and glycidyl (meth)acrylate; by addition of bisphenols such as bisphenol A, bisphenol F, hydrogenated bisphenol A, or their alkylene oxides glycidyl ethers produced by reaction with epichlorohydrin, Novolac epoxy resins, etc., glycidyl ether type epoxy resins derived from bisphenols, etc.

The above-mentioned hard coat composition may further contain a polymerization initiator. As a polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, etc. are mentioned, It can select and use suitably. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating, generate radicals or cations, and perform radical polymerization and cationic polymerization.

The radical polymerization initiator may be capable of releasing a substance that initiates radical polymerization by at least one of active energy ray irradiation and heating. For example, as a thermal radical polymerization initiator, organic peroxides, such as hydrogen peroxide and peroxybenzoic acid, azo compounds, such as azobisisobutyronitrile, etc. are mentioned.

As active energy ray radical polymerization initiators, there are Type 1 type radical polymerization initiators that generate radicals by molecular decomposition, and Type 2 type radical polymerization initiators that generate radicals by hydrogen abstraction type reaction in coexistence with tertiary amines , they can be used alone or in combination.

The cationic polymerization initiator may be capable of releasing a substance that initiates cationic polymerization by at least one of active energy ray irradiation and heating. As the cationic polymerization initiator, an aromatic iodonium salt, an aromatic sulfonium salt, a cyclopentadienyl iron (II) complex, or the like can be used. For them, cationic polymerization can be initiated by either or both of active energy ray irradiation or heating, depending on the difference in structure.

It is preferable to contain the said polymerization initiator in 0.1-10 mass % with respect to 100 mass % of the said hard-coat composition whole. When the content of the above-mentioned polymerization initiator is within the above-mentioned range, curing can be sufficiently advanced, the mechanical properties and adhesive force of the finally obtained coating film can be brought into a good range, and there is adhesive force due to curing shrinkage. Defects, cracking, and curling tend to be less likely to occur.

The said hard-coat composition may further contain 1 or more types chosen from the group which consists of a solvent and an additive.

The above-mentioned solvent is a solvent capable of dissolving or dispersing the above-mentioned polymerizable compound and polymerization initiator, and as long as it is a solvent known as a solvent of a hard coat composition in the technical field, it can be used without hindering the present invention. used within the range of the effect.

The above-mentioned additives may further contain inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

The optical laminate of the present invention can be used, for example, in a flexible image display device, and among them, a foldable display device and a rollable display device can be suitably used.

<Flexible Image Display Device>

The flexible image display device of the present invention includes the optical laminate of the present invention. For example, a flexible image display device is formed of an optical laminate (a laminate for a flexible image display device) and an organic EL display panel, and the laminate for a flexible image display device is arranged on the viewing side of the organic EL display panel so as to be foldable constitute. The laminate for a flexible image display device may further contain a window, a polarizing plate, and a touch sensor, and the lamination order of these may be arbitrary, but preferably the window, the polarizing plate, the touch sensor, or the window, the touch sensor, and the polarizing plate in the order from the viewing side cascading. When a polarizing plate is present on the viewing side of the touch sensor, the pattern of the touch sensor is not easily observed, and the visibility of the displayed image becomes good, which is preferable. Each member can be laminated using an adhesive, a pressure-sensitive adhesive, or the like. In addition, a light-shielding pattern formed on at least one surface of any one of the above-mentioned window, polarizing plate, and touch sensor may be provided. The polarizer may be a circular polarizer.

(window)

The window is arranged on the viewing side of the flexible image display device, and plays a role of protecting other components from external impact and environmental changes such as temperature and humidity. Conventionally, glass has been used as such a protective layer, but the window in a flexible image display device is not rigid and hard like glass, but has a flexible property. The above-mentioned window is formed of a flexible transparent base material, and may contain a hard coat layer on at least one side. The hard coat layer optionally contained in the window has the same meaning as the hard coat layer which the above-mentioned optical laminate has.

(Polarizer)

The polarizing plate, wherein the circular polarizing plate is a functional layer having a function of transmitting only a right-handed or left-handed circularly polarized light component by laminating a λ/4 retardation plate on a linear polarizing plate. For example, it can be used to convert external light into right-handed circularly polarized light, block the external light that is reflected by the organic EL panel and become left-handed circularly polarized light, and only transmit the light-emitting component of the organic EL, thereby suppressing the influence of reflected light , thereby making it easy to view the image. In order to achieve the function of circularly polarized light, the absorption axis of the linear polarizer and the slow axis of the λ/4 retardation plate need to be 45° in theory, but 45±10° in practical applications. The linear polarizer and the λ/4 retardation plate do not necessarily have to be stacked adjacent to each other, and the relationship between the absorption axis and the slow axis may satisfy the above-mentioned range. It is preferable to achieve complete circularly polarized light at all wavelengths, but this is not necessary in practical applications. Therefore, the circularly polarizing plate in the present invention also includes an elliptically polarizing plate. It is also preferable that a λ/4 retardation film is further laminated on the viewing side of the linear polarizing plate to make the outgoing light circularly polarized, thereby improving visibility in a state of wearing polarized sunglasses.

The linear polarizer is a functional layer having a function of passing light vibrating in the direction of the transmission axis and blocking polarized light of a vibration component perpendicular thereto. The linear polarizer may be a single linear polarizer or a linear polarizer and a structure including a protective film bonded to at least one surface of the linear polarizer. The thickness of the linear polarizing plate may be 200 μm or less, and preferably 0.5 to 100 μm. When the thickness is within the above-mentioned range, there is a tendency that the flexibility does not decrease easily.

The above-mentioned linear polarizer may be a film-type polarizer produced by dyeing and stretching a polyvinyl alcohol (PVA)-based film. Polarization performance can be exhibited by adsorbing dichroic dyes such as iodine on the PVA-based film oriented by stretching, or by stretching the dichroic dyes in a state of being adsorbed on PVA to orientate the dichroic dyes. In the production of the above-mentioned film-type polarizer, steps such as swelling, crosslinking by boric acid, washing by aqueous solution, and drying may be further included. The stretching and dyeing process may be performed as a PVA-based film alone, or may be performed in a state of being laminated with another film such as polyethylene terephthalate. The thickness of the PVA-based film to be used is preferably 10 to 100 μm, and the stretching 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 may be sufficient. The above-mentioned liquid crystal polarizing composition may contain a liquid crystal compound and a dichroic dye compound. The above-mentioned liquid crystalline compound only needs to have a property of exhibiting a liquid crystal state, and it is preferable that it exhibits a high polarization performance especially when it has a high-order alignment state such as smectic. In addition, the liquid crystal compound preferably has a polymerizable functional group.

The above-mentioned dichroic dye is a dye that is aligned together with the above-mentioned liquid crystal compound and exhibits dichroism, and the dichroic dye itself may have liquid crystallinity or a polymerizable functional group. Any compound in the liquid crystal polarizing composition has a polymerizable functional group.

The above-mentioned liquid crystal polarizing composition may further contain an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like.

The above circular polarizing plate may be a liquid crystal polarizing layer. The said liquid crystal polarizing layer is manufactured by apply|coating a liquid crystal polarizing composition on an alignment film, and forming a liquid crystal polarizing layer.

Compared with the film-type polarizer, the liquid crystal polarizing layer can be formed with a thinner thickness. The thickness of the liquid crystal polarizing layer may be preferably 0.5 to 10 μm, and more preferably 1 to 5 μm.

The said alignment film can be manufactured by apply|coating an alignment film forming composition on a base material, and providing orientation by rubbing, polarized light irradiation, etc., for example. The above-mentioned composition for forming an alignment film may contain, in addition to the alignment agent, a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. As the above-mentioned alignment agent, for example, polyvinyl alcohols, polyacrylates, polyamic acids, and polyimides can be used. In the case of applying photo-alignment, an alignment agent containing a cinnamate group is preferably used. The weight average molecular weight of the polymer which can be used as the said alignment agent can be about 10,000-1,000,000. The thickness of the above-mentioned alignment film is preferably 5 to 10,000 nm, and more preferably 10 to 500 nm, from the viewpoint of the alignment regulating force. The said liquid crystal polarizing layer may be laminated|stacked after peeling from a base material, and it may transcribe|transfer, and the said base material may be laminated|stacked as it is. It is also preferable that the above-mentioned base material functions as a transparent base material for a protective film, a retardation plate, and a window.

As said protective film, what is necessary is just to be a transparent polymer film, and the material and additive which can be used for the said transparent base material can be used. Cellulose-based films, olefin-based films, acrylic-based films, and polyester-based films are preferred. It may be a coating-type protective film obtained by coating and curing a cationic curing composition such as epoxy resin or a radical curing composition such as acrylate. If necessary, plasticizers, ultraviolet absorbers, infrared absorbers, pigments, colorants such as dyes, optical brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, and lubricants may be contained , solvent, etc. The thickness of the said protective film may be 200 micrometers or less, Preferably it is 1-100 micrometers. When the thickness of the said protective film is in the said range, the flexibility of a protective film is hard to fall. The protective film may also function as a transparent substrate for the window.

The above-mentioned λ/4 retardation plate is a film which imparts a retardation of λ/4 in the direction orthogonal to the advancing direction of the incident light (the in-plane direction of the film). The above-mentioned 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, and a polycarbonate-based film. As needed, retardation modifiers, plasticizers, ultraviolet absorbers, infrared absorbers, pigments, colorants such as dyes, optical brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, Antioxidants, lubricants, solvents, etc. The thickness of the above-mentioned stretched retardation plate may be 200 μm or less, and preferably 1 to 100 μm. When the thickness is within the above-mentioned range, the flexibility of the film tends to be less likely to decrease.

Moreover, as another example of the said λ/4 retardation plate, the liquid crystal coating type retardation plate formed by apply|coating a liquid crystal composition may be sufficient. The above-mentioned liquid crystal composition includes a liquid crystal compound having a property of exhibiting a liquid crystal state such as nematic, cholesteric, and smectic. Any compound including the liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The above-mentioned liquid crystal coating type retardation plate may further contain an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The said liquid crystal coating-type retardation plate can be manufactured by apply|coating a liquid crystal composition on an alignment film, hardening, and forming a liquid crystal retardation layer similarly to the description of the said liquid crystal polarizing layer. Compared with the stretched retardation film, the liquid crystal coated retardation film can be formed with a thinner thickness. The thickness of the above-mentioned liquid crystal polarizing layer can be usually 0.5 to 10 μm, preferably 1 to 5 μm. The above-mentioned liquid crystal coating-type retardation plate may be laminated after being peeled from the base material, or the above-mentioned base material may be directly laminated. It is also preferable that the above-mentioned base material functions as a transparent base material for a protective film, a retardation plate, and a window.

In general, the shorter the wavelength, the greater the birefringence, and the longer the wavelength, the smaller the birefringence is, there are many materials. In this case, since the retardation of λ/4 cannot be achieved in the entire visible light region, it is often designed so that the in-plane retardation becomes 100 to 180 nm, preferably 130 to 150 nm, such that the in-plane retardation becomes λ/4 in the vicinity of 560 nm, where the visibility is high. . It is preferable to use a reverse dispersion λ/4 retardation plate using a material having a birefringence wavelength dispersion characteristic opposite to that of usual, since visibility can be improved. As such a material, also in the case of a stretched retardation plate, it is preferable to use the material described in Japanese Patent Laid-Open No. 2007-232873, etc., and in the case of a liquid crystal coating type retardation plate, it is preferable to use the The material described in the publication No. 2010-30979.

In addition, as another method, a technique for obtaining a wide-band λ/4 phase difference plate by combining with a λ/2 phase difference plate is also known (Japanese Patent Laid-Open No. 10-90521). The λ/2 retardation plate can also be manufactured using the same material method as the λ/4 retardation plate. The combination of a stretched retardation plate and a liquid crystal coating type retardation plate is arbitrary, and it is preferable to use a liquid crystal coating type retardation plate because the thickness can be reduced.

For the above-mentioned circularly polarizing plate, in order to improve the visibility in the oblique direction, a method of laminating a positive C plate is also known (Japanese Patent Laid-Open No. 2014-224837). The positive C plate can also be a liquid crystal coating type retardation plate or a stretched type retardation plate. The retardation in the thickness direction is -200 to -20 nm, preferably -140 to -40 nm.

(Manufacturing method of circularly polarizing plate)

An example of the manufacturing method of a circularly polarizing plate is demonstrated. When manufacturing a circularly polarizing plate including a polarizing layer and a retardation layer in this order, first, the polarizing layer and the retardation layer are separately formed. For example, the polarizing layer is formed by laminating an alignment layer, a polarizer, and a protective layer in this order on a protective film serving as a base material. In addition, a λ/4 retardation plate and a positive C plate were bonded together using an adhesive to form a retardation layer.

Next, the formed polarizing layer and retardation layer were bonded together using an adhesive to manufacture a circularly polarizing plate. In the bonding of the polarizing layer and the retardation layer, the polarizing layer and the retardation layer are bonded so that the absorption axis of the polarizing layer becomes substantially 45° with respect to the slow axis (optical axis) of the retardation layer. In this way, a pressure-sensitive adhesive layer/polarizing layer (protective film/alignment layer/polarizer/protective layer)/adhesive layer/retardation layer (λ/4 retardation plate/positive C plate) can be produced in this order. ) of the circular polarizer.

The laminate having a circularly polarizing plate of the present invention (hereinafter, also referred to as an optical laminate) includes the optical film of the present invention.

(Formula (39))

The optical laminate of the present invention with a circularly polarizing plate satisfies the formula (39):

Transmission b*-reflection (SCE)b*≥4.0...(39)

[In the formula (39), transmission b* represents b* in the L*a*b* colorimetric system of light transmitted from the optical laminate, and reflection (SCE) b* represents the value obtained by the SCE method in this optical b*] in the L*a*b* colorimetric system of light reflected by the stack.

When the optical laminate having a circular polarizing plate of the present invention satisfies Equation (39), the light transmission from the light source is increased, the reflection of external light is decreased, and the reflected b* hue is decreased, which is close to the neutral hue. Excellent visibility.

From the viewpoint of further improving the visibility of the optical laminate having a circularly polarizing plate, the numerical value of the formula (39) (transmission b*-reflection (SCE) b*) is preferably 4.2 or more, more preferably 4.5 or more, and still more preferably It is 5.0 or more, and it is especially preferable that it is 6.5 or more.

(Formula (40))

From the viewpoint of further improving the visibility, the optical laminate having a circularly polarizing plate of the present invention preferably satisfies the formula (40):

Transmission b*-reflection (SCI)b*≥4.5...(40)

[In the formula (40), transmission b* represents b* in the L*a*b* colorimetric system of the light transmitted from the above-mentioned optical laminate, and reflection (SCI) b* represents the above optical layer obtained by the SCI method b*] in the L*a*b* colorimetric system of light reflected by the stack.

When the optical laminate having a circularly polarizing plate of the present invention satisfies the formula (40), the reflection b* hue becomes small and closes to a neutral hue, so that it has excellent visibility.

From the viewpoint of further improving the visibility of the optical laminate having a circularly polarizing plate, the numerical value of the formula (40) (transmission b*-reflection (SCI) b*) is preferably 4.7 or more, more preferably 5.5 or more, still more preferably is 6.0 or higher.

(transmission b*)

The transmission b* of an optical laminate having a circularly polarizing plate is b* in the L*a*b* colorimetric system of light transmitted from the optical laminate, and in this specification, refers to the following incident light (white b* value in the CIE1976L*a*b* colorimetric system of the transmitted light of light), the incident light (white light) is incident from the perpendicular direction to the plane of the optical laminate with the circular polarizer, and the wavelength is 380-780nm Incident light (white light) in the range. The transmission b* is preferably 4.0 or more, more preferably 5.0 or more, and still more preferably 6.0 or more. The transmission b* of the optical laminated body which has a circular polarizing plate can be measured using an ultraviolet-visible-near-infrared spectrophotometer, for example, it can be measured by the method as described in an Example.

(Reflection(SCE)b*)

The reflection (SCE) b* of the optical laminate having a circularly polarizing plate is b* in the L*a*b* colorimetric system of the light reflected by the optical laminate obtained by the SCE method, and in this specification, is Refers to the b* value of the CIE1976L*a*b* colorimetric system of the diffuse reflection light excluding specular reflection light among the reflected light of the following incident light obtained from an optical system having a circularly polarizing plate Incident light within a wavelength range of 380 to 780 nm that is incident in a direction in which the vertical direction of the laminate plane is inclined by a predetermined angle. The reflection (SCE) b* is preferably 1.5 or less, preferably 1.0 or less, more preferably 0 or less, and particularly preferably -1.5 or less. The reflection (SCE) b* of the optical laminate having a circularly polarizing plate can be measured using a spectrophotometer, for example, by the method described in Examples.

(Reflection (SCI)b*)

The reflection (SCI) b* of the optical laminate having a circularly polarizing plate is b* in the L*a*b* colorimetric system of the light reflected by the optical laminate obtained by the SCI method, and in this specification, is Refers to the b* value in the CIE1976L*a*b* colorimetric system of reflected light (reflected light including specularly reflected light) relative to the incident light obtained from an optical system with a circularly polarized plate Incident light within a wavelength range of 380 to 780 nm that is incident in a direction in which the vertical direction of the laminate plane is inclined by a predetermined angle. The reflection (SCI) b* of the optical laminate having a circularly polarizing plate can be measured using a spectrophotometer, for example, by the method described in Examples.

As means for adjusting the transmission b*-reflection (SCE)b* in the formula (39) within a predetermined numerical range, for example, adjusting the transmission b*-reflection (SCE)b* of the optical film to the formula ( The means within the numerical range of 1), and the hue adjustment based on the composition change of the window.

In addition, as a means to adjust the transmission b*-reflection (SCI) b* in the formula (40) within a predetermined numerical range, for example, adjusting the transmission b*-reflection (SCI) b* of the optical film to The means within the numerical range of the formula (2), and the hue adjustment based on the composition change of the window.

(touch sensor)

A touch sensor can be used as an input mechanism. As the touch sensor, various methods such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and an electrostatic capacitance method have been proposed, and any method may be used. Among them, the electrostatic capacitance method is preferable. The capacitive touch sensor can be divided into an active area and an inactive area located at the periphery of the active area. The active area is an area corresponding to an area (display portion) on the display panel that displays a screen, and is an area that senses the user's touch, and the inactive area is an area corresponding to an area (non-display portion) of the display device that does not display a screen. The touch sensor may include: a substrate having flexible properties; a sensing pattern formed on an active area of the substrate; and an inactive area formed on the substrate for connecting the sensing pattern to the sensing pattern via a pad portion Each sensing line connected to an external drive circuit. As the substrate having flexible properties, the same material as the transparent substrate of the above-mentioned window can be used. The substrate of the touch sensor preferably has a toughness of 2,000 MPa% or more from the viewpoint of suppressing cracks in the touch sensor. The toughness may be more preferably 2,000 to 30,000 MPa%. Here, toughness is defined as the lower area of the curve up to the point of failure in a stress (MPa)-strain (%) curve (Stress-strain curve) obtained by a tensile test of a polymer material.

The above-mentioned sensing pattern may include a first pattern formed along the first direction and a second pattern formed along the second direction. The first pattern and the second pattern are arranged in mutually different directions. The first pattern and the second pattern are formed on the same layer, and in order to sense the touched position, the patterns must be electrically connected. The first pattern has a configuration in which the unit patterns are connected to each other through joints, and the second pattern has a configuration in which the unit patterns are separated from each other in an island form. Therefore, separate bridge electrodes are required to electrically connect the second patterns. A known transparent electrode raw material can be applied to the sensing pattern. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), indium gallium zinc oxide (IGZO), cadmium tin oxide ( CTO), PEDOT (poly(3,4-ethylenedioxythiophene), poly(3,4-ethylenedioxythiophene)), carbon nanotubes (CNT), graphene, wire, etc., which can be used alone or mixed 2 Use more than one species. Preferably ITO can be used. The metal that can be used for the wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, chromium, and the like. These can be used individually or in mixture of 2 or more types.

The bridge electrode may be formed on the above-mentioned insulating layer via an insulating layer on the upper portion of the sensing pattern, and the bridge electrode may be formed on the substrate, and the insulating layer and the 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 a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of these. The first pattern and the second pattern must be electrically insulated, so an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the contact of the first pattern and the bridge electrode, or may be formed to cover the layer of the sensing pattern. In the latter case, the bridge electrode may connect the second pattern through a contact hole formed in the insulating layer. In the above-mentioned touch sensor, as a method for appropriately compensating the difference in transmittance between the patterned area and the non-patterned area where the pattern is formed (specifically, the transmittance caused by the difference in refractive index in these areas) An optical adjustment layer may be further included between the substrate and the electrode, and the optical adjustment layer may include an inorganic insulating substance or an organic insulating substance. The optical adjustment layer can be formed by apply|coating the photocurable composition containing a photocurable organic binder and a solvent on a board|substrate. The above-mentioned photocurable composition may further contain inorganic particles. The refractive index of the optical adjustment layer can be increased by the above-mentioned inorganic particles.

The said photocurable organic binder can contain the copolymer of each monomer, such as an acrylate type monomer, a styrene type monomer, and a carboxylic acid type monomer, for example. The above-mentioned photocurable organic binder may be, for example, a copolymer containing each repeating unit different from each other, such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit.

The above-mentioned inorganic particles may contain, for example, zirconium dioxide particles, titanium dioxide particles, alumina particles, and the like. The said photocurable composition may further contain each additive, such as a photoinitiator, a polymerizable monomer, and a curing adjuvant.

(adhesive layer (adhesive layer))

Each layer (window, polarizing plate, touch sensor) forming the above-mentioned laminate for flexible image display devices and film members (linear polarizing plate, λ/4 retardation plate, etc.) constituting each layer can be formed by an adhesive. As the adhesive, water-based adhesives, organic solvent-based, solvent-free adhesives, solid adhesives, solvent-volatile adhesives, moisture-curable adhesives, heat-curable adhesives, Anaerobic curing type, active energy ray curing type adhesive, curing agent mixed type adhesive, hot melt type adhesive, pressure sensitive adhesive (adhesive), rewet type adhesive, etc. are commonly used adhesive. Among them, water-based solvent-volatile adhesives, active energy ray-curable adhesives, and adhesives are commonly used. The thickness of the adhesive layer can be appropriately adjusted according to the required adhesive force, etc., and is 0.01 to 500 μm, preferably 0.1 to 300 μm. There are multiple adhesive layers in the above-mentioned laminate for flexible image display devices. The kinds of adhesives may be the same or different.

As the above-mentioned water-based solvent-volatile adhesive, polyvinyl alcohol-based polymers, water-soluble polymers such as starch, and polymers in a water-dispersed state such as ethylene-vinyl acetate-based emulsions and styrene-butadiene-based emulsions can be used. main agent polymer. In addition to water and the above-mentioned main ingredient polymer, a cross-linking agent, a silane-based compound, an ionic compound, a cross-linking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be blended. In the case of adhering with the above-mentioned water-based solvent volatile adhesive, adhesion can be imparted by injecting the above-mentioned water-based solvent volatile adhesive between layers to be adhered, and after bonding the layers to be adhered, and drying. sex. The thickness of the adhesive layer in the case of using the above-mentioned water-based solvent volatile adhesive may be 0.01 to 10 μm, preferably 0.1 to 1 μm. When the above-mentioned water-based solvent-volatile adhesive is used for the formation of multiple layers, the thickness of each layer and the type of the above-mentioned adhesive may be the same or different.

The above-mentioned active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition containing a reactive material capable of forming an adhesive layer by irradiating an active energy ray. The said active energy ray hardening composition may contain the polymer of at least 1 sort(s) of a radical polymerizable compound and a cationically polymerizable compound similar to a hard-coat composition. The aforementioned radically polymerizable compound can be used in the same manner as the hard coat composition, and the same type of radical polymerizable compound as the hard coat composition can be used. As a radical polymerizable compound which can be used for an adhesive layer, the compound which has an acryl group is preferable. In order to reduce the viscosity as an adhesive composition, it is also preferable to contain a monofunctional compound.

The above-mentioned cationically polymerizable compound is the same as that of the hard coat layer composition, and the same kind of cationically polymerizable compound as the hard coat layer composition can be used. As a cationically polymerizable compound that can be used in the active energy ray-curable composition, an epoxy compound is particularly preferable. In order to reduce the viscosity as an adhesive composition, it is also preferable to contain a monofunctional compound as a reactive diluent.

In the active energy ray composition, a polymerization initiator may be further contained. The polymerization initiator includes a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, and the like, which can be appropriately selected and used. These polymerization initiators can be decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations, thereby enabling radical polymerization and cationic polymerization to proceed. An initiator capable of initiating at least any one of radical polymerization and cationic polymerization by active energy ray irradiation described in the description of the hard coat composition can be used.

The above-mentioned active energy ray-curable composition may further contain an ion trapping agent, an antioxidant, a chain transfer agent, an adhesion imparting agent, a thermoplastic resin, a filler, a fluid viscosity modifier, a plasticizer, an antifoaming agent, an additive, and a solvent. In the case of adhering with the above-mentioned active energy ray-curable adhesive, the adhesion can be carried out by applying the above-mentioned active energy ray-curing composition to one or both of the layers to be adhered, and then bonding, An active energy ray is irradiated through one to-be-adhered layer or both to-be-adhered layers, and it hardens|cures. The thickness of the adhesive layer in the case of using the above-mentioned active energy ray-curable adhesive may be 0.01 to 20 μm, preferably 0.1 to 10 μm. When the above-mentioned active energy ray-curable adhesive is used for the formation of multiple layers, the thickness of each layer and the type of the adhesive used may be the same or different.

The above-mentioned adhesives are classified into acrylic adhesives, urethane-based adhesives, rubber-based adhesives, silicone-based adhesives, and the like according to the main ingredient polymer, and any of them can be used. In the adhesive, in addition to the main polymer, crosslinking agents, silane-based compounds, ionic compounds, crosslinking catalysts, antioxidants, tackifiers, plasticizers, dyes, pigments, inorganic fillers, etc. . An adhesive can be formed by dissolving and dispersing each component constituting the adhesive in a solvent to obtain an adhesive composition, applying the adhesive composition on a substrate, and drying it. Floor. The adhesive layer may be directly formed, or an adhesive layer formed separately on the substrate may be transferred. In order to cover the adhesive surface before bonding, it is also preferable to use a release film. The thickness of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive is used may be 1 to 500 μm, preferably 2 to 300 μm. When the above-mentioned adhesive is used for the formation of multiple layers, the thickness of each layer and the type of the adhesive to be used may be the same or different.

(shading pattern)

The above-mentioned light-shielding pattern may be applied as at least a part of a bezel or a casing of the above-mentioned flexible image display device. The wiring arranged on the edge of the flexible image display device is hidden by the light-shielding pattern so as to be difficult to be observed, thereby improving the visibility of the image. The above-mentioned light-shielding pattern may be in the form of a single layer or a multilayer. The color of the light-shielding pattern is not particularly limited, and may have various colors such as black, white, and metallic. The light-shielding pattern can be formed of a pigment for expressing color, and a polymer such as acrylic resin, ester resin, epoxy resin, polyurethane, and silicone. These may be used individually, or may be used as a mixture of 2 or more types. The above-mentioned light-shielding pattern can be formed by various methods such as printing, photolithography, and inkjet. The thickness of the light-shielding pattern is usually 1 to 100 μm, preferably 2 to 50 μm. In addition, it is also preferable to provide a shape such as an inclination in the thickness direction of the light-shielding pattern.

Example

Hereinafter, the present invention will be described in more detail by way of examples. Unless otherwise indicated, "%" and "part" in an example mean mass % and mass part. First, the evaluation method will be described.

<1. Measurement method>

(Reflection (SCE)b* and Reflection (SCI)b* of Optical Film)

The optical films obtained in the examples and comparative examples were cut into a size of 50×50 mm, and then bonded to black PET (“Kukkiri Mieru”, manufactured by Bachuan Seisakusho Co., Ltd.) to obtain samples for reflection optical measurement.

The hue of the obtained sample for evaluation was measured by the SCE method (removal of specular reflection light) and the SCI method (including specular reflection light) using a spectrophotometer ("CM-3700A" manufactured by Konica Minolta Co., Ltd.). . The measurement diameter was LAV: 8 mm in diameter, the measurement conditions were di: 8°, de: 8° (diffusion illumination and light reception in the 8° direction), the measurement field of view was 2°, the light source was a D65 light source, and the UV condition was 100% Full. Here, the hue refers to a* and b* in the CIE1976L*a*b* color space. In addition, the reflection (SCE) a* and the reflection (SCI) a* of the optical film were also measured under the same conditions as above.

(Reflection (SCE)b* and Reflection (SCI)b* of an optical laminate with a circular polarizer)

For the reflection (SCE)b* and reflection (SCI)b* of the optical laminate having a circularly polarizing plate, the measurement object was changed from the optical film to the optical laminate having a circularly polarizing plate. The measurement method of . In addition, reflection (SCE)a* and reflection (SCI)a* were also measured in the same manner.

(Visual transmittance Y of laminate with circular polarizer)

The visual transmittance Y is a physical property value representing the lightness of the color of an object in the XYZ color system. The visual transmittance Y was measured using a spectrophotometer ("CM-2600d" manufactured by Konica Minolta Co., Ltd.).

(Transmission b* of optical film)

The optical films obtained in Examples and Comparative Examples were cut into a size of 50 mm×50 mm, and the transmitted light was measured using a spectrophotometer (“CM-3700A” manufactured by Konica Minolta Co., Ltd.). The measurement diameter was set to LAV: 25.4 mm in diameter, and the measurement field of view was set to 2°. In addition, a D65 light source was used as the measurement light source, and the UV condition was set to 100% Full. Here, the hue refers to a* and b* in the CIE1976L*a*b* color space.

(Transmission b* of an optical laminate with a circular polarizer)

The transmission b* of the optical laminate having a circularly polarizing plate was measured in the same manner as the measuring method of an optical film, except that the measurement object was changed from an optical film to an optical laminate having a circularly polarizing plate. Moreover, the transmission a* of the optical laminated body which has a circular polarizing plate was also measured in the same manner.

(Film thickness of optical film and adhesive layer)

Using a micrometer ("ID-C112XBS" manufactured by Mitutoyo Co., Ltd.), the film thickness of 10 or more locations of the optical film was measured, and the average value was calculated. The thickness of the pressure-sensitive adhesive layer was measured in the same manner, and the average value was calculated.

(Total light transmittance and haze of optical film)

The total light transmittance of the optical film was measured according to JIS K 7361-1:1997, and the haze was measured according to JIS K7136: 2000, using a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd. The optical films of Examples and Comparative Examples were cut into a size of 30 mm×30 mm to prepare measurement samples.

(Yellow Index of Optical Film)

The yellowness index (Yellow Index: YI value) of the optical film was measured using an ultraviolet-visible-near-infrared spectrophotometer (“V-670” manufactured by JASCO Corporation). The background measurement was performed without the sample, and then the optical films obtained in the examples and comparative examples were installed in the sample holder, and the transmittance with respect to light of 300 to 800 nm was measured, and tristimulus values (X, Y, Z) were obtained. ). From the obtained tristimulus values, the YI value was calculated based on the following formula based on the ASTM D1925 standard.

YI=100×(1.2769X-1.0592Z)/Y

(Particle Size of Silica Particles)

The particle diameter of the silica particles was calculated from the measured value of the specific surface area by the BET adsorption method in accordance with JIS Z 8830. The specific surface area of the powder obtained by drying the silica sol at 300° C. was measured using a specific surface area measuring apparatus (“MONOSORB (registered trademark) MS-16” manufactured by Yuasa-ionics Co., Ltd.).

(weight average molecular weight)

Gel permeation chromatography (GPC) assay

(1) Pretreatment method

The sample was dissolved in γ-butyrolactone (GBL) to prepare a 20 mass % solution, then diluted 100-fold with the DMF eluent, filtered through a 0.45 μm membrane filter, and the obtained filtrate was used as a measurement solution.

(2) Measurement conditions

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

Eluent: DMF (addition of 10 mmol of lithium bromide)

Flow: 0.6mL/min

Detector: RI detector

Column temperature: 40℃

Injection volume: 20μL

Molecular weight standard: standard polystyrene

(imidization rate)

The imidization rate was measured by ¹ H-NMR, and was calculated|required as follows.

(1) Pretreatment method

An optical film containing a polyimide-based resin was dissolved in deuterated dimethyl sulfoxide (DMSO-d ₆ ) to prepare a 2 mass % solution, which was used as a measurement sample.

(2) Measurement conditions

Measuring apparatus: JNM-ECZ400S/L1 400MHz NMR apparatus manufactured by JEOL

Standard material: DMSO-d ₆ (2.5ppm)

Sample temperature: room temperature

Cumulative times: 256 times

Relaxation time: 5 seconds

(3) Analysis method of imidization rate

(imidization rate of polyimide resin)

Among the benzene protons observed in the ¹ H-NMR spectrum obtained for the measurement sample containing the polyimide resin, the integral value of the benzene proton A derived from the structure that did not change before and after imidization was defined as Int _A. In addition, let the integral value of the observed amide proton derived from the amic-acid structure remaining in the polyimide resin be Int _B . From these integrated values, the imidization rate of the polyimide resin was determined based on the following formula.

Imidization ratio (%)=100×(1-α×Int _B /Int _A )

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

(imidization rate of polyamide-imide resin)

Among the benzene protons observed in the ¹ H-NMR spectrum obtained for the measurement sample containing the polyamideimide resin, the protons were derived from the structure that did not change before and after imidization, and were not derived from the polyamide amide The integral value of the benzene proton C which is influenced by the structure of the amic acid structure remaining in the imine resin is set to Int _C . In addition, let the integral value of the benzene proton D derived from the structure that does not change before and after imidization and is influenced by the structure derived from the amic acid structure remaining in the polyamideimide resin among the observed benzene protons is set as Int _D . From the obtained Int _C and Int _D , the β value was obtained by the following formula.

β=Int _D /Int _C

Next, with respect to a plurality of polyamide-imide resins, the β value of the above formula and the imidization ratio of the polyimide resin of the above formula were obtained, and from these results, the following correlation formula was obtained.

Imidization rate (%)=k×β+100

In the above correlation formula, k is a constant.

The imidization ratio (%) of the polyamide-imide resin was obtained by substituting β into the correlation formula.

(Calculation of HSP value of resin)

The solubility in the solvent of the polyamideimide resin 1 (PAI-1) was evaluated. In a transparent container, 10 mL of a solvent having known solubility parameters shown in Table 1 (source: Polymer Handbook 4th Edition) and 0.1 g of polyamideimide resin 1 were put into a mixed solution. The obtained mixture was subjected to ultrasonic treatment for a total of 6 hours. The appearance of the mixed solution after the ultrasonic treatment was visually observed, and based on the obtained observation results, the solubility of the polyamideimide resin 1 in the solvent was evaluated based on the following evaluation criteria. The evaluation results are shown in Table 1. In addition, similarly, about polyamide-imide resin 2 (PAI-2) and polyimide resin 1 (PI), the polyamide-imide in the polyamide-imide resin 1-solvent system was changed Resin 1 and the type of resin were evaluated for solubility in a solvent in the same manner.

(Evaluation Criteria)

1: The appearance of the mixed solution is cloudy.

0: The appearance of the mixed solution is transparent.

[Table 1]

Based on the results of evaluation of the solubility of the obtained resin in a solvent, Hansen spheres were produced using the above-described Hansen dissolving sphere method. The center coordinates of the obtained Hansen sphere were taken as the HSP value. The results are shown in Table 2.

[Table 2]

(Calculation of HSP value of silica)

The solvent was removed from the silica sol 1, and the silica 1 as a solid component was taken out. The dispersibility of the silica 1 in the solvent was evaluated. In a transparent container, 10 mL of a solvent with known solubility parameters shown in Table 3 (source: Polymer Handbook 4th Edition) and 0.1 g of silica 1 were put into a mixed solution. The obtained mixture was subjected to ultrasonic treatment for a total of 6 hours. The appearance of the mixed solution after the ultrasonic treatment was visually observed, and based on the obtained observation results, the dispersibility of the silica 1 in the solvent was evaluated based on the following evaluation criteria. The evaluation results are shown in Table 3. Note that, similarly, methanol-dispersed silica sol (“MA-ST-L” manufactured by Nissan Chemical Industry Co., Ltd., primary particle size: 20 to 25 nm) and methanol-dispersed silica sol (Silica Sol 2, primary particle A diameter of 10 to 12 nm), the dispersibility in a solvent was evaluated in the same manner, except that the type of the silica sol used as the raw material in the silica 1-solvent system was changed.

(Evaluation Criteria)

1: The appearance of the mixed solution is cloudy.

0: The appearance of the mixed solution is transparent.

[table 3]

Based on the results of evaluation of the dispersibility in the solvent of each silica dispersed in the silica sol, Hansen spheres were produced using the above-described Hansen dissolving sphere method. The center coordinates of the obtained Hansen sphere were taken as the HSP value. The results are shown in Table 4.

[Table 4]

(HSP value of resin-silica system)

From Table 2 and Table 4, the HSP value of the resin-silica system was calculated using the formulae (6) to (9). The results are shown in Table 5.

[table 5]

As shown in Table 5, the Ra, Δδ _t , and Δδp of the silica 1, 2-resin systems were smaller than those of the silica (MA-ST-L)-resin system, respectively, Ra, Δδ _t , and Δδp. In addition, Ra, Δδ _t , and Δδp of the silica 1 and 2-resin systems satisfy formulas (3) to (5), respectively.

(Elastic Modulus)

The elastic modulus (tensile elastic modulus) G' of the pressure-sensitive adhesive layer was measured by a tensile test in accordance with JIS K 7127 using an electromechanical universal testing machine (manufactured by Instron Corporation). The measurement conditions were a test speed of 5 m/min and a load cell of 5 kN.

<2. Evaluation method>

(Evaluation of Visibility of Optical Film)

A film is provided on the surface of the liquid crystal display device as a front panel to display white or black, and the observer observes the optical film visually at an angle of 45° from the vertical direction of the optical film plane. From the observation results, the visibility of the optical film was evaluated based on the following evaluation criteria. From the best case, it is represented by ⊚, ∘, Δ, and × in this order.

(Evaluation Criteria for Visibility of Optical Films)

⊚: Both the white display and the black display are completely free of yellow.

〇: Both the white display and the black display are slightly yellowish.

△ : At least one of white display and black display is slightly yellowish.

×: Both the white display and the black display are yellowish. In addition, white is displayed in black display.

(Evaluation of Visibility of Optical Laminate with Circularly Polarizing Plate)

An optical laminate having a circularly polarizing plate was placed on the surface of a reflective plate (aluminum plate, reflectivity 97%), and the optical laminate was visually inspected by an observer at an angle of 45° from the vertical direction of the plane of the optical laminate. Observed. From the observation results, the visibility of the optical laminate having the circularly polarizing plate was evaluated based on the following evaluation criteria. From the best case, 0, Δ, and × are shown in this order.

(Evaluation Criteria for Visibility of Optical Laminates with Circular Polarizing Plate)

○: Hue change on a 45° inclined plane on the reflective plate compared to the vertical direction The front hue on the reflective plate is neutral, and there is no hue change due to the viewing angle.

△: Compared with the vertical direction on the reflector, the hue change on the 45° inclined plane The front color on the reflector is neutral, and the hue change due to the viewing angle is slightly larger.

×: Compared with the vertical direction, on the reflector, the hue change on the 45° inclined plane The front color on the reflector is neutral X, and the color change by the viewing angle is large.

<3. Manufacture of optical film>

[3-1. Production of polyimide-based resin]

[Production Example 1: Polyimide Resin 1]

Prepare a reaction vessel including a silicone tube, a stirring device and a thermometer, and an oil bath attached to the separable flask. 75.52g of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) and 54.44g of 2,2'-bis(tris(tris(tris)) were put into the reaction vessel installed in the oil bath Fluoromethyl)-4,4'-diaminobiphenyl (TFMB). While stirring the contents of the reaction vessel at 400 rpm, 519.84 g of N,N-dimethylacetamide (DMAc) was further put into the reaction vessel, and stirring was continued until the contents of the reaction vessel became a homogeneous solution . Next, stirring was continued for further 20 hours while adjusting the temperature in the container to be in the range of 20 to 30° C. using an oil bath, and the reaction proceeded to generate a polyamic acid. After 30 minutes, the stirring speed was changed to 100 rpm. After stirring for 20 hours, the temperature of the reaction system was returned to room temperature (25° C.), and 649.8 g of DMAc was further put into the reaction vessel so that the polymer concentration was 10% by mass (based on the total mass of the contents in the reaction vessel) way to adjust. Furthermore, 32.27 g of pyridine and 41.65 g of acetic anhydride were put into the reaction container, and the mixture was stirred at room temperature for 10 hours to carry out imidization. Remove the polyimide varnish from the reaction vessel. The obtained polyimide varnish was added dropwise to methanol to perform reprecipitation. The precipitate was taken out by filtration and dried to obtain powder. The obtained powder was further heated and dried to remove the solvent to obtain a polyimide resin 1 as a solid content. The weight average molecular weight of the obtained polyimide resin 1 was 320,000, and the imidization rate was 98.6%.

[Production Example 2: Polyamideimide Resin 1]

Under a nitrogen atmosphere, a reaction vessel equipped with a stirring blade in a separable flask with a capacity of 1 L, and an oil bath were prepared. Into the reaction vessel set in the oil bath, 45 g of TFMB (140.52 mmol) and 768.55 g of DMAc were put. The contents of the reaction vessel were stirred at room temperature to dissolve TFMB in DMAc. Next, 18.92 g (42.58 mmol) of 6FDA was further put into the reaction container, and the contents in the reaction container were stirred at room temperature for 3 hours. Then, 4.19 g (14.19 mmol) of 4,4'-oxybis(benzoyl chloride) (OBBC) was put into the reaction vessel, followed by 17.29 g (85.16 mmol) of terephthaloyl chloride (TPC), and the reaction was carried out. The contents of the vessel were stirred at room temperature for 1 hour. Next, 4.63 g (49.68 mmol) of 4-picoline and 13.04 g (127.75 mmol) of acetic anhydride were further charged 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 container was raised to 70° C. using an oil bath, and the content in the reaction container was further stirred for 3 hours while maintaining at 70° C. to obtain a reaction liquid.

The obtained reaction liquid was cooled to room temperature, and poured into a large amount of methanol in a linear manner to deposit a precipitate. The deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the reduced pressure drying of the precipitate was performed at 100 degreeC, and the polyamide-imide resin was obtained. The weight average molecular weight of the polyamideimide resin was 400,000, and the imidization rate was 98.8%.

[Production Example 3: Polyamideimide Resin 2]

Under a nitrogen atmosphere, a reaction vessel equipped with a stirring blade in a separable flask with a capacity of 1 L, and an oil bath were prepared. Into a reaction vessel set in an oil bath, 45 g (140.52 mmol) of TFMB and 768.55 g of DMAc were put. TFMB was dissolved in DMAc while stirring the contents of the reaction vessel at room temperature. Next, 19.01 g (42.79 mmol) of 6FDA was further put into the reaction container, and the contents in the reaction container were stirred at room temperature for 3 hours. Then, 4.21 g (14.26 mmol) of OBBC and 17.30 g (85.59 mmol) of TPC were charged into the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 1 hour. Next, 4.63 g (49.68 mmol) of 4-picoline and 13.04 g (127.75 mmol) of acetic anhydride were further charged 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 container was raised to 70° C. using an oil bath, and the temperature was maintained at 70° C. and further stirred for 3 hours to obtain a reaction liquid.

The obtained reaction liquid was cooled to room temperature, and poured into a large amount of methanol in a linear manner to deposit a precipitate. The deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the reduced pressure drying of the precipitate was performed at 100 degreeC, and the polyamide-imide resin was obtained. The weight average molecular weight of the obtained polyamide-imide resin was 365,000, and the imidization rate was 98.9%.

[3-2. Production of silica particles]

[Production Example 4: Silica Sol 1]

A flask with a capacity of 1 L as a reaction vessel, and a hot water bath were prepared. Into a reaction vessel set in a hot water bath, 442.6 g of methanol-dispersed silica sol (primary particle size: 25 nm, silica solid content: 30.5%) and 301.6 g of γ-butyrolactone were charged. The temperature in the container was set to 45°C using a hot water bath, and the pressure in the reaction container was maintained at 400 hPa using an evaporator for 1 hour. Then, the pressure in the reaction container was maintained at 250 hPa for 1 hour to evaporate methanol. Furthermore, the pressure in the reaction vessel was set to 250 hPa, and the temperature in the vessel was raised to 70° C. and heated for 30 minutes. As a result, a γ-butyrolactone-dispersed silica sol (Silica Sol 1, SGS7#09) was obtained. The solid content of the obtained γ-butyrolactone-dispersed silica sol was 28.9%.

[Production Example 5 Silica Sol 2]

Except that the primary particle size of the methanol-dispersed silica sol was changed to 10 nm and the solid content of silica was changed to 22%, solvent replacement was carried out in the same manner as in Production Example 4 to obtain γ-butane having a solid content of 20%. Lactone-dispersed silica sol (Silica Sol 2).

[Production Example 6 Silica Sol 3]

Methanol-dispersed silica sol (primary particle size: 25 nm, silica solid content: 30.5%) was changed to methanol-dispersed silica sol (“MA-ST-L” manufactured by Nissan Chemical Industries, Ltd., primary particle size: 40 to 50 nm) ), solvent replacement was performed in the same manner as in Production Example 4 to obtain a γ-butyrolactone-dispersed silica sol (silica sol 3) having a solid content of 30.5% and a primary particle diameter of 50 nm.

[3-3. Manufacture of varnish]

[Production Example 7 Varnish 1]

To γ-butyrolactone, in the composition shown in Table 6, polyamideimide resin 1, silica sol 1, Sumisorb (registered trademark) 340 as an ultraviolet absorber, and Sumiplast (registered trademark) as a brightening agent were added. Trademark) Violet B, the varnish 1 was prepared so that a solid content might become 10.2%.

In Table 6, the unit wt % of the contents in the columns of "resin" and "silica particles" represents the ratio (mass %) with respect to the total mass of the resin and the silica particles. The unit phr of the content in the column of "ultraviolet absorber" represents the ratio (mass %) with respect to the total mass of the resin and the silica particles.

[Table 6]

[Production Examples 8 to 13: Varnishes 2 to 8]

The composition (type and/or content of components) shown in Table 6 was changed, the substituted solvent was changed from γ-butyrolactone to N,N-dimethylacetamide, and the solid content concentration of the resin was changed to 11.0% , varnish 3 was prepared in the same manner as varnish 1 except that. Moreover, except having changed to the composition (kind and/or content of components) shown in Table 6, by the same method as the varnish 1, the varnishes 2 and 4-8 were prepared, respectively.

[Example 1]

[3-4. Manufacture of optical film]

The obtained varnish 1 was cast-molded on a PET film ("Cosmoshine (registered trademark) A4100" manufactured by Toyobo Co., Ltd.), and molded into a coating film. The conveyance speed of the PET in the tape casting was 0.3 m/min. Then, the coating film was dried by heating at 80° C. for 20 minutes and at 90° C. for 20 minutes, and the coating film was peeled off from the PET film. Then, the polyamideimide film 1 with a film thickness of 51 μm was obtained by heating while stretching the coating film in the lateral direction at 200° C. for 12 minutes with a tenter.

[Example 2]

Except having changed the film thickness of application|coating, it carried out similarly to Example 1, and obtained the polyamideimide film 2 with a film thickness of 29 micrometers.

[Example 3]

Except having changed the varnish 1 to the varnish 2, it carried out similarly to Example 1, and obtained the polyamide-imide film 3 with a film thickness of 50 micrometers.

[Example 4]

Except having changed the varnish 1 to the varnish 3, it carried out similarly to Example 1, and obtained the polyamide-imide film 4 with a film thickness of 49 micrometers.

[Example 5]

Except having changed the varnish 1 to the varnish 4, it carried out similarly to Example 1, and obtained the polyamide-imide film 5 with a film thickness of 48 micrometers.

[Example 6]

Except having changed the varnish 1 to the varnish 5, it carried out similarly to Example 1, and obtained the polyamide-imide film 6 with a film thickness of 48 micrometers.

[Example 7]

Except having changed the varnish 1 to the varnish 6, it carried out similarly to Example 1, and obtained the polyimide film 7 with a film thickness of 78 micrometers.

[Comparative Example 1]

Except having changed the varnish 1 to the varnish 7, it carried out similarly to Example 1, and obtained the polyimide film 8 with a film thickness of 52 micrometers.

[Comparative Example 2]

Except having changed the varnish 1 to the varnish 8, it carried out similarly to Example 1, and obtained the polyamide-imide film 9 with a film thickness of 50 micrometers.

[Table 7]

The optical films of Examples 1 to 7 satisfy the formula (1), and the evaluation of their visibility is any one of ⊚, ∘, and Δ. The optical films of Comparative Examples 1 to 2 contained polyamideimide and did not satisfy the formula (1), and the evaluation results of their visibility were x.

It turned out that the optical film of Examples 1-7 is excellent in visibility compared with the optical film of Comparative Examples 1-2.

[Example 8]

[3-5. Manufacture of adhesive layer]

(Preparation of the composition for forming an adhesive layer)

Based on the composition described in Table 8, a composition for forming an adhesive layer was prepared. In Table 8, BA represents butyl acrylate. MMA stands for methyl methacrylate. HEA stands for hydroxyethyl acrylate. AA stands for acrylic. The addition amount of the crosslinking agent and the SC agent is the mass relative to 100 parts by mass of the monomer.

[Table 8]

(Formation of Adhesive Layer 1)

On the release-treated surface of the release-treated substrate (polyethylene terephthalate film, thickness 38 μm), the composition 1 for forming an adhesive layer was applied with an applicator to form a coating layer . The coating layer was dried at 100° C. for 1 minute to form the pressure-sensitive adhesive layer 1 . The thickness of the adhesive layer 1 was 25 μm.

Next, another base material (polyethylene terephthalate film, thickness 38 μm) subjected to mold release treatment was bonded on the pressure-sensitive adhesive layer 1 . Then, it aged for 7 days under the conditions of a temperature of 23 degreeC, and a relative humidity of 50% RH. Thereby, the film provided with the adhesive layer 1 was obtained. The elastic modulus G' and thickness of the obtained pressure-sensitive adhesive layer 1 were measured. The measurement results are summarized in Table 9.

In the following, when the pressure-sensitive adhesive layer is laminated, after the pressure-sensitive adhesive layer is laminated, the release-treated base material is peeled off.

(Formation of Adhesive Layer 2)

The composition 1 for forming a pressure-sensitive adhesive layer was changed to the composition for forming a pressure-sensitive adhesive layer 2, and the composition for forming a pressure-sensitive adhesive layer was applied so that the thickness of the pressure-sensitive adhesive layer was 5 μm. Formation of the mixture layer 1 was performed in the same manner to form the adhesive layer 2 . The elastic modulus and thickness of the adhesive layer 2 are summarized in Table 9.

[Table 9]

[3-6. Manufacture of polarizing plate]

(Preparation of composition for forming alignment film)

The polymer 1 is a photoreactive group-containing polymer containing the following structural units.

According to GPC measurement, the molecular weight of the obtained polymer 1 was 28,200 in terms of number average molecular weight, the degree of dispersion (Mw/Mn) was 1.82, and the monomer content was 0.5%. A solution obtained by dissolving the polymer 1 in cyclopentanone at a concentration of 5 mass % was used as the composition for forming an alignment film.

(Formation of alignment film)

On the protective film (triacetyl cellulose: TAC), the said composition for alignment film formation was apply|coated by the bar coating method, and the coating film was formed. The coating film was dried at 80°C for 1 minute. Next, using a UV irradiation device (SPOT CURE SP-7, manufactured by USHIO INC.) and a wire grid (“UIS-27132##”, manufactured by USHIO INC.), the exposure amount was 100 mJ/cm ² (365 nm standard). ), the coating film was irradiated with polarized UV light. Thus, an alignment film is formed on the protective film. The alignment film has alignment properties, and its thickness is 100 nm.

(Preparation of the composition for forming a polarizer)

The composition for forming a polarizer contains a polymerizable liquid crystal compound and a dichroic dye.

(polymerizable liquid crystal compound)

As the polymerizable liquid crystal compound, a polymerizable liquid crystal compound represented by formula (5) [hereinafter, also referred to as compound (5)] and a polymerizable liquid crystal compound represented by formula (6) [hereinafter, also referred to as compound (6)] were used.

[Chemical formula 5]

[Chemical formula 6]

Compound (5) and compound (6) were synthesized by the method described in Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996).

(Dichroic Pigments)

As the dichroic dye, the azo dyes represented by the following formulae (7), (8) and (9) and described in the Examples of JP-A No. 2013-101328 were used.

[Chemical formula 7]

[Chemical formula 8]

[Chemical formula 9]

(Preparation of the composition for forming a polarizer)

The composition for forming a polarizer was prepared by mixing 75 parts by mass of compound (5), 25 parts by mass of compound (6), and the above-mentioned formula (7), formula (8), and formula (9) as dichroic dyes. ), 2.5 parts by mass of azo dyes each, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)-1-butanone (Irgacure369, BASF Japan) as a polymerization initiator 6 parts by mass) and 1.2 parts by mass of a polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) as a leveling agent were mixed with 400 parts by mass of toluene, and the resulting mixture was stirred at 80° C. for 1 hour.

(Manufacture of polarizers)

On the formed alignment film, the above-mentioned composition for forming a polarizer was applied by a bar coating method to form a coating film. The coating film was heated and dried at 100°C for 2 minutes. Next, it cooled to room temperature. Using the above-mentioned UV irradiation apparatus, the coating film was irradiated with ultraviolet rays under the condition of a cumulative light amount of 1200 mJ/cm ² (365 nm reference). Thus, a polarizer is formed on the alignment film. The thickness of the polarizer was 3 μm.

(Formation of protective layer)

On the polarizer, a composition containing polyvinyl alcohol and water is applied to form a coating film. The coating film was dried at a temperature of 80°C for 3 minutes. Thus, a protective layer is formed on the polarizer. The thickness of the protective layer was 0.5 μm.

By the above-mentioned method, the polarizing layer which laminated|stacked a protective film, an alignment film, a polarizer, and a protective layer in this order was manufactured.

(Formation of λ/4 retardation plate and positive C plate)

The λ/4 retardation plate is formed in the following manner.

The components shown below were mixed, and the resulting mixture was stirred at 80° C. for 1 hour to obtain a composition for forming a λ/4 retardation layer.

Compound b-1 represented by the following formula: 80 parts by mass

Compound b-2 represented by the following formula: 20 parts by mass

Polymerization initiator (Irgacure369, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)-1-butanone, manufactured by BASF Japan): 6 parts by mass

Leveling agent (BYK-361N, polyacrylate compound, manufactured by BYK-Chemie): 0.1 part by mass

Cyclopentanone: 400 parts by mass

On a first base film (thickness 100 μm, polyethylene terephthalate film (PET)), the above-mentioned composition for forming an alignment film was applied by a bar coating method, and heated and dried in an oven at 80° C. for 1 minute. . The polarized UV light irradiation process was performed to the obtained dry film, and the 2nd alignment film was formed. The polarized UV light treatment was performed using the above-mentioned UV irradiation apparatus under the condition that the cumulative light amount measured at a wavelength of 365 nm was 100 mJ/cm ² . Moreover, it carried out so that the polarization direction of polarized UV light might become 45 degrees with respect to the absorption axis of a polarizing layer. In this way, the laminated body formed of "1st base material film/2nd alignment film" is obtained. The thickness of the second alignment film was 100 nm.

The composition for forming a λ/4 retardation layer was applied on the second alignment film of the laminate composed of the "first base film/second alignment film" by a bar coating method, and heated in a drying oven at 120°C. Dry for 1 minute, then cool to room temperature. A retardation layer was formed by irradiating the obtained dried film with ultraviolet rays having a cumulative light intensity of 1000 mJ/cm ² (365 nm reference) using the above-mentioned UV irradiation apparatus. The thickness of the obtained retardation layer was measured with a laser microscope (OLS3000 manufactured by Olympus Co., Ltd.) and found to be 2.0 μm. The retardation layer is a λ/4 plate that exhibits a retardation value of λ/4 in the in-plane direction. In this manner, a laminate composed of "the first base film/the second alignment film/λ/4 retardation layer" is obtained.

Each component shown below was mixed, and the obtained mixture was stirred at 80 degreeC for 1 hour, and the composition for positive C retardation layer formation was obtained by this.

A compound represented by the following formula (LC242, manufactured by BASF Japan): 100 parts by mass

Polymerization initiator (Irgacure907, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, manufactured by BASF Japan): 2.6 parts by mass

Leveling agent (BYK-361N, polyacrylate compound, manufactured by BYK-Chemie): 0.5 parts by mass

Additive (LR9000, manufactured by BASF Japan): 5.7 parts by mass

Solvent (propylene glycol 1-monomethyl ether 2-acetate): 412 parts by mass

On the second base film (thickness 100 μm, polyethylene terephthalate film (PET)) similarly to the above-mentioned λ/4 retardation plate, the above-mentioned composition for forming an alignment film was applied by the bar coating method. , heated and dried in a drying oven at 90° C. for 1 minute to form a third alignment film. Then, on the third alignment film, the composition for forming a positive C retardation layer was applied by a bar coating method, heated and dried in a drying oven at 90° C. for 1 minute, and then, in a nitrogen atmosphere, using the above-mentioned UV irradiation apparatus, A positive C plate was formed by irradiating ultraviolet rays with a cumulative light amount of 1000 mJ/cm ² (365 nm reference). The thickness of the obtained positive C plate was measured with a laser microscope (OLS3000 manufactured by Olympus Co., Ltd.), and as a result, it was 1.8 μm.

Then, using the pressure-sensitive adhesive layer 2, the surface of the positive C plate from which the second base film was peeled was bonded to the side opposite to the first base film of the above-mentioned λ/4 retardation plate, thereby producing a phase Poor layer.

Both the formed λ/4 retardation plate and positive C plate include layers in which the polymerizable liquid crystal compound is cured in an oriented state.

[3-7. Manufacture of optical laminate with circularly polarizing plate]

Using the polyamideimide film 1 , the polarizing layer, the pressure-sensitive adhesive layer 1 , and the pressure-sensitive adhesive layer 2 , the optical laminate 1 was produced. The laminate 1 includes a polyamideimide film 1 / an adhesive layer 1 / a polarizing layer (protective film / alignment film / polarizer / protective layer) / an adhesive layer 2 in this order. Through the pressure-sensitive adhesive layer 2, the surface of the retardation layer from which the first base film was peeled was bonded to the opposite side to the protective film side of the polarizing layer. The retardation layer is a layer obtained by laminating a λ/4 retardation plate (RWP) and a positive C plate (PosiC). Then, the pressure-sensitive adhesive layer 1 is provided on the opposite side of the above-mentioned retardation layer to the polarizing layer. Thus, the laminated body 1 including the circularly polarizing plate was produced. Laminate 1 includes polyamideimide film 1/adhesive layer 1/polarizing layer (protective film/alignment film/polarizer/protective layer)/adhesive layer 2/retardation layer (λ/4 retardation layer) in this order board/positive C board)/adhesive layer 1. Here, the description of the alignment film in the retardation layer is omitted.

In addition, regarding the bonding of the polarizing layer and the retardation layer, the pressure-sensitive adhesive layer is interposed so that the absorption axis of the polarizing layer becomes substantially 45° with respect to the slow axis (optical axis) of the retardation layer. 2. Laminate the polarizing layer and the retardation layer.

Optical property values were measured and calculated for the optical laminate having the circularly polarizing plate. Specifically, transmission b*, transmission a*, a*, b* and Y in reflection (SCE) method, and a*, b* and Y in reflection (SCI method) were measured. From the obtained transmission b* and reflection (SCE) b*, transmission b*-reflection (SCE) b* was calculated. The measurement results and calculation results are summarized in Table 10.

[Example 9]

Except having applied the polyamideimide film 5 to the front panel instead of the polyamideimide film 1 , it was carried out in the same manner as in Example 8 to manufacture an optical laminate 2 having a circularly polarizing plate, and the optical properties were measured and calculated. value.

[Example 10]

Except that the polyimide film 7 was applied to the front panel instead of the polyamideimide film 1, it was carried out in the same manner as in Example 8 to manufacture an optical laminate 3 having a circularly polarizing plate, and the optical property values were measured and calculated. .

[Comparative Example 3]

Except having applied the polyimide film 8 to the front panel instead of the polyamideimide film 1, it was carried out in the same manner as in Example 8 to manufacture an optical laminate 4 having a circularly polarizing plate, and the optical property values were measured and calculated. .

[Table 10]

The optical laminates having the circularly polarizing plates of Examples 8 to 10 satisfy the formula (39), and the evaluation of their visibility is either ○ or Δ. In addition, the optical laminates having the circularly polarizing plates of Examples 8 to 10 also satisfy the formula (40).

The optical laminate having the circularly polarizing plate of Comparative Example 3 did not satisfy the formula (39), and the evaluation of the visibility was x. In addition, the optical laminate having the circularly polarizing plate of Comparative Example 3 also did not satisfy the formula (40).

It turned out that the optical laminated body which has a circular polarizing plate of Examples 8-10 is excellent in visibility compared with the optical laminated body which has a circular polarizing plate of the comparative example 3.

Claims (10)

1. An optical film comprising at least one selected from the group consisting of polyimide, polyamide, and polyamideimide, and satisfying formula (1):

1.1. ltoreq. transmission b x-reflection (SCE) b x 15 … … (1)

In formula (1), transmission b denotes light transmitted from the optical film in the L × a × b color system, and reflection (SCE) b denotes light reflected from the optical film in the L × a × b color system, which is determined by SCE.

2. The optical film according to claim 1, which further satisfies formula (2):

transmission b reflection (SCI) b ≦ 4.5 … … (2)

In formula (2), transmission b represents light transmitted from the optical film in the L a b color system, and reflection (SCI) b represents light reflected from the optical film in the L a b color system, which is determined in the SCI manner.

3. The optical film according to claim 1 or 2, wherein the haze is 1% or less and the total light transmittance Tt is 85% or more.

4. The optical film according to claim 1 or 2, further comprising silica particles.

5. The optical film according to claim 4, wherein the silica particles are silica particles obtained by solvent substitution of a water-soluble alcohol-dispersed silica sol.

6. The optical film according to claim 1 or 2, further comprising an ultraviolet absorber.

7. An optical laminate comprising: the optical film according to any one of claims 1 to 6; and a hard coat layer on at least one side of the optical film.

8. A flexible image display device comprising the optical laminate according to claim 7.

9. The flexible image display device according to claim 8, further comprising a polarizing plate.

10. The flexible image display device according to claim 8 or 9, further provided with a touch sensor.