KR20210003876A - Optical films, optical laminates and flexible image display devices - Google Patents

Abstract

When used suitably as an optical film in an image display device, it aims at providing the optical film which has both excellent feeding stability and excellent film appearance. An optical film containing at least one member selected from the group consisting of polyimide, polyamide and polyamideimide, wherein the formula (1)
0.04≤reflection (SCE) b*/reflection (SCI) b*≤1.5 ... (1)
[In formula (1), reflection (SCE) b* represents b* in the L*a*b* color system of the light reflected by the optical film obtained by the SCE method, and reflection (SCI) b* is the SCI method Indicates b* in L*a*b* color system of light reflected from the optical film determined by
To meet the optical film.

Description

Optical films, optical laminates and flexible image display devices

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

In recent years, an optical film containing a polyimide resin has been used as a functional film for imparting functions to image display devices such as televisions, personal computers, smart phones, tablets, and electronic papers. Since a user of such an image display device directly visually recognizes an image displayed with the naked eye through an optical film applied to the display device, the optical film is required to have an excellent film appearance.

Defects in the appearance of the film include, for example, a defect derived from the composition of the optical film and a defect derived from the method of manufacturing the optical film. The former is a defect in which an additive (more specifically, silica particles, etc.) interacts with visible light and the appearance is damaged, for example. In the latter case, in the case of manufacturing an optical film by a roll-to-roll method excellent in mass production, the optical film is not smoothly fed out from the roll due to, for example, an inadequate tag of the optical film, and the optical film It is a defect in which the surface of the optical film is scratched by sliding between them. For this reason, in the latter, the delivery stability (unwind stability) of the optical film is required.

Japanese Unexamined Patent Application Publication No. 2009-215412

However, according to the study of the present inventors, the two appearance defects are in a trade-off relationship, and for example, an optical film containing a polyimide resin and silica particles as described in Patent Document 1 There were cases where it was not compatible with a high level.

Accordingly, an object of the present invention is to provide an optical film having both excellent feeding stability and excellent film appearance, and an optical laminate and a flexible image display device including the optical film.

The present inventors, as a result of earnestly examining in order to solve the above problems, in an optical film containing at least one selected from the group consisting of polyimide, polyamide, and polyamideimide, reflecting (SCE) b*/reflection ( When SCI) b* is adjusted to a predetermined range, it has found that the problem can be solved, and the present invention is completed. That is, the following aspects are included in this invention.

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

0.04≤reflection (SCE) b*/reflection (SCI) b*≤1.50 ... (1)

[In formula (1), reflection (SCE) b* represents b* in the L*a*b* color system of the light reflected by the optical film obtained by the SCE method, and reflection (SCI) b* is the SCI method Indicates b* in L*a*b* color system of light reflected from the optical film determined by

To meet the optical film.

[2] Equation (2)

Reflection (SCE) a*/Reflection (SCI) a*≤2.5 ··· (2)

[In formula (2), reflection (SCE) a* represents a* in the L*a*b* color system of the light reflected by the optical film obtained by the SCE method, and reflection (SCI) a* is the SCI method Represents a* in L*a*b* color system of light reflected from the optical film obtained by

The optical film according to [1], further satisfying.

[3] The optical film according to [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 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 substitution of a water-soluble alcohol-dispersed silica sol.

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

[7] further comprising silica particles,

The three-dimensional distance Ra determined by the Hansen melting sphere method is Equation (3)

Ra≤8.0 ... (3)

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

The optical film in any one of [1] to [6] that satisfies.

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

[9] A flexible image display device comprising 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 comprising a touch sensor.

Advantageous Effects of Invention According to the present invention, when used as an optical film in an image display device, an optical film having both excellent feeding stability and excellent film appearance can be provided. Further, according to the present invention, it is possible to provide an optical laminate and a flexible image display device comprising an optical film having both excellent feeding stability and excellent film appearance.

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

<optical film>

The optical film of the present invention contains at least one selected from the group consisting of polyimide, polyamide and polyamideimide, and formula (1)

0.04≤reflection (SCE) b*/reflection (SCI) b*≤1.50 ... (1)

[In formula (1), reflection (SCE) b* represents b* in the L*a*b* color system of the light reflected by the optical film obtained by the SCE method, and reflection (SCI) b* is the SCI method Indicates b* in L*a*b* color system of light reflected from the optical film determined by

Meets.

[One. Equation (1)]

When the ratio [reflection (SCE) b*/reflection (SCI) b*] of the optical film of the present invention is 0.1 or more, since the surface of the optical film has an appropriate smoothness, the optical film has an appropriate tack. , It is excellent in feeding stability, and appearance defects resulting from sliding between optical films are hard to occur. On the other hand, if the ratio [reflection (SCE) b*/reflection (SCI) b*] of the formula (1) of the optical film of the present invention is 1.9 or less, appearance defects derived from the composition of the optical film are unlikely to occur, The film appearance is excellent. Therefore, when the formula (1) is satisfied, both excellent feeding stability and excellent film appearance are provided. The ratio [reflection (SCE) b*/reflection (SCI) b*] of the optical film of the formula (1) is preferably 0.05 or more, more preferably, from the viewpoint of further improving feeding stability and/or film appearance. 0.1 or more, more preferably 0.13 or more. In addition, the ratio [reflection (SCE) b*/reflection (SCI) b*] of the optical film is preferably 1.4 or less, more preferably from the viewpoint of further improving feeding stability and/or film appearance. It is preferably 1.2 or less, more preferably 1.1 or less. Such a plurality of upper and lower limits can be arbitrarily combined.

(Reflection (SCE) b*)

The reflection (SCE) b* of the optical film is b* in the L*a*b* color system of the light reflected by the optical film obtained by the SCE (Specular Component Excluded: specular reflection light is excluded) method, and the present specification In CIE 1976 L*a*b* color system of diffusely reflected light excluding regular reflected light among reflected light for incident light in a wavelength range of 380 to 780 nm, incident from a direction oblique at a predetermined angle from the vertical direction of the optical film plane Refers to the b* value of 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 -0.08 or less, preferably -0.1 or less, and more preferably -0.3 or less. Such a plurality of upper and lower limits can be arbitrarily combined. The reflection (SCE) b* of the optical film can be measured using, for example, a spectrophotometer. The measurement method can be measured by the method described in Examples.

(Reflection (SCI) b*)

The reflection (SCI) b* of the optical film is b* in the L*a*b* color system of the light reflected by the optical film obtained by the SCI (Specular Component Included: regular reflected light) method, and the present specification In CIE 1976 L*a*b* color system of reflected light (reflected light including regular reflected light) for incident light in a wavelength range of 380 to 780 nm, incident from a predetermined angle oblique direction from the vertical direction of the optical film plane Refers to the b* value of The reflection (SCI) b* is preferably -2.9 or more, more preferably -2.7 or more, and still more preferably -2.5 or more. The reflection (SCI) b* is preferably -1.4 or less, more preferably -1.6 or less, and still more preferably -2.0 or less. Such a plurality of upper and lower limits can be arbitrarily combined. The reflection (SCI) b* of the optical film can be measured using, for example, a spectrophotometer. The measurement method can be measured by the method described in Examples.

As a means for adjusting the numerical value of Formula (1) within a predetermined numerical range, a means for reducing the interaction between white light and a component in the optical film can be mentioned, for example. As a means of reducing the interaction, for example, the film thickness of the optical film, the addition of additives (more specifically, silica particles, ultraviolet absorbers, and brighteners, etc.), properties of the additive (more specifically, particle diameter , Surface modification, and a means for adjusting the content, etc.) to a predetermined range. Among these, the adjustment of the particle size, surface modification, and content of the silica particles makes it difficult for the silica particles to be agglomerated in the optical film and to exist in the form of primary particles, so that the silica particles are uniform in the optical film. Easily distributed. In addition, since the interaction with the white light due to the uneven shape on the surface of the optical film is reduced, and the interaction between the aggregate and the white light in the optical film is reduced, the decrease in visibility is suppressed (deterioration of the film appearance quality. It is thought to contribute to the suppression).

[2. Equation (2)]

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

Reflection (SCE) a*/Reflection (SCI) a*≤2.5 ··· (2)

[In formula (2), reflection (SCE) a* represents a* in the L*a*b* color system of the light reflected by the optical film obtained by the SCE method, and reflection (SCI) a* is the SCI method Represents a* in L*a*b* color system of light reflected from the optical film obtained by

Meets.

When the optical film satisfies the formula (2), the delivery stability and/or the film appearance of the optical film are further improved. The ratio [reflection (SCE) a*/reflection (SCI) a*] of the optical film is preferably 2.2 or less, from the viewpoint of further improving the feeding stability and/or the film appearance of the optical film. It is preferably 2.0 or less, more preferably 1.8 or less. In addition, the ratio [reflection (SCE) a*/reflection (SCI) a*] of the optical film is preferably 0.0 or more from the viewpoint of further improving the feeding stability and/or the film appearance of the optical film. , More preferably 0.1 or more. Such a plurality of upper and lower limits can be arbitrarily combined. As a means for adjusting the numerical value of the formula (2) within a predetermined numerical range, for example, a means for adjusting the numerical value of the above formula (1) within a predetermined numerical range may be mentioned.

(Reflection (SCE) a*)

The reflection (SCE) a* of the optical film is a* in the L*a*b* color system of the light reflected by the optical film determined by the SCE method, and in this specification, it is determined from the vertical direction of the optical film plane. It refers to the a* value of the CIE 1976 L*a*b* colorimetric system of diffusely reflected light excluding the regular reflected light among the reflected light of the incident light in the wavelength range of 380 to 780 nm incident from an angle oblique direction. Reflection (SCE) a* is preferably -0.01 or more, preferably 0.0 or more. The reflection (SCE) a* is preferably 0.6 or less, preferably 0.5 or less, and more preferably 0.4 or less. Such a plurality of upper and lower limits can be arbitrarily combined. The reflection (SCE) a* of the optical film can be measured using, for example, a spectrophotometer. The measurement method can be measured by the method described in Examples.

(Reflection (SCI) a*)

The reflection (SCI) a* of the optical film is a* in the L*a*b* color system of the light reflected by the optical film determined by the SCI method, and in this specification, it is determined from the vertical direction of the optical film plane. It refers to the a* value of the CIE 1976 L*a*b* color system of reflected light (reflected light including regular reflected light) with respect to incident light in a wavelength range of 380 to 780 nm incident from an angle oblique direction. The reflection (SCI) a* is preferably -0.03 or more, more preferably 0.0 or more, and still more preferably 0.1 or more. The reflection (SCI) a* is preferably 0.28 or less, more preferably 0.27 or less, and still more preferably 0.26 or less. Such a plurality of upper and lower limits can be arbitrarily combined. The reflection (SCI) a* of the optical film can be measured using, for example, a spectrophotometer. The measurement method can be measured by the method described in Examples.

[3. Hayes]

The haze of the optical film of the present invention is preferably 1% or less, more preferably 0.8% or less, further preferably 0.5% or less, particularly from the viewpoint of further improving the feeding stability and/or film appearance of the optical film. It is preferably 0.3% or less. The haze of the optical film can be measured according to JIS K 7136:2000. The measurement method will be described in detail in Examples. Since the haze of the optical film indicates the degree of dispersibility of the additive in the optical film, when the haze of the optical film is within the above range, the delivery stability of the optical film and/or the film appearance are 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 still more preferably 89% or more. The total light transmittance of the optical film can be measured according to JIS K7361-1:1997. The measurement method will be described in detail in Examples. When the total light transmittance of the optical film is within the above numerical range, a sufficient film appearance can be ensured when introduced into an image display device. In addition, if the total light transmittance of the optical film is within the above numerical range, it is possible to easily secure a constant brightness, so for example, it becomes possible to suppress the light emission intensity of a display element, etc., thereby reducing the power consumption of the image display device. I can.

[5. Yellowness]

The yellowness of the optical film of the present invention is preferably 3.0 or less, more preferably 2.7 or less, and still more preferably 2.5 or less. The yellowness degree of an optical film can be measured in conformity with JIS K 7373:2006. The measurement method will be described in detail 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 still more preferably 30 µm or more. Further, the film thickness is preferably 120 µm or less, more preferably 100 µm or less, still more preferably 80 µm or less, and particularly preferably 60 µm or less. If the film thickness is 30 µm or more, it is advantageous from the viewpoint of internal protection when the optical film is used as a device, and if the film thickness is 120 µm or less, it is advantageous from the viewpoint of cutting resistance, cost, transparency, and the like. The measurement method will be described in detail in Examples.

[7. Solubility parameter]

The inventors of the present invention have found that the composition in the optical film causes agglomeration and the like due to poor dispersion and deteriorates the appearance quality of the film, and thus a solute in a solid system such as an optical film (e.g., additive, more specifically , UV absorbers, silica particles, and brighteners, etc.) and media (e.g., resin, more specifically, at least one resin selected from the group consisting of polyimide, polyamide and polyamideimide) The Hansen Solubility Parameter (HSP may be omitted hereinafter) was introduced as an index to evaluate. As a result of intensive examination by the present inventor, the following formulas (3) to (5) were derived. That is, in the optical film of the present invention, from the viewpoint of suppressing the deterioration of the appearance quality of the film (particularly, the viewpoint of suppressing the occurrence of a problem with white rice), Equation (3) relating to HSP

Ra≤8.0 ... (3)

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

It is desirable to meet.

In addition, the optical film of the present invention, from the viewpoint of further suppressing the deterioration of the film appearance quality, in addition to the formula (3), the formula (4) related to the HSP

Δδ _t ≤ 2.0 ... (4) [In formula (4), Δδ _t represents the difference of the total δ _t of the dispersion term, polarity term and hydrogen bonding term of HSP between the solute and the medium]

, Or Equation (5)

Δδ _p ≤4.5 ... (5) [In formula (5), Δδ _p represents the difference in the polarity term δ _p of HSP between the solute and the medium]

It is more preferable to satisfy.

In addition, it is more preferable that the optical film of the present invention satisfies all of the formulas (3) to (5) from the viewpoint of further suppressing the decrease in film appearance quality.

(7-1. Calculation method of HSP value)

The HSP value is calculated using the Hansen Solubility Sphere method. The details will be described below. The target composition (the solute and the medium) is dissolved or dispersed in a solvent having a known HSP value to evaluate the solubility or dispersibility of the composition in a specific solvent. Evaluation of solubility and dispersibility is performed by visually determining whether or not the target composition is dissolved in a solvent and whether or not it is dispersed. This is done for a plurality of solvents. As for the kind of this solvent, it is preferable to use a solvent whose δ _t is widely different, and more specifically, it is preferably 10 or more, more preferably 15 or more, and even more preferably 18 or more. Subsequently, the obtained solubility or dispersibility evaluation result is plotted in a three-dimensional space (HSP space) consisting of a dispersion term δ _d , a polar term δ _p and a hydrogen bonding term δ _h of HSP. Create a sphere (Hansen sphere) in which a solvent in which the composition of the object is dissolved or dispersed is contained inside, and a solvent in which the composition of the object is not dissolved or dispersed becomes the outer side, and the radius is minimized. Let HSP of the composition targeting the center coordinates (δ _d , δ _p , δ _h ) of the obtained Hansen sphere.

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

7-1. Using the method of calculating the HSP value, the HSP values (δ _d1 , δ _p1 , δ _h1 : component 1 when two kinds of components in the optical film, for example, resin as component 1 and silica as component 2 are used) The HSP value, δ _d2 , δ _p2 , δ _h2 : HSP value of component 2) was calculated.

The total δ _t of the dispersion term, the polar term, and the hydrogen bonding term of HSP and the difference Δδ _t of the sum between the components 1 and 2 are calculated using equations (6) and (7), respectively. The obtained δ _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)

Δδ _t is preferably 3.5 or less, more preferably 3.0 or less, still more preferably 2.0 or less, even more preferably 1.0 or less, particularly preferably 0.5 or less from the viewpoint of further suppressing the deterioration of the film appearance quality. to be.

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

Δδ _p =|δ _p2 -δ _p1 | ··· (8)

Δδ _p is preferably 4.5 or less, more preferably 3.5 or less, still more preferably 3.0 or less, even more preferably 2.0 or less, particularly preferably 1.0 or less from the viewpoint of further suppressing the deterioration of the film appearance quality to be.

The three-dimensional distance Ra (>0) between the component 1 and the component 2 in the HSP space is calculated using equation (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. The Ra value is preferably 8.0 or less, more preferably 7.0 or less, still more preferably 6.0 or less, even more preferably 5.5 or less, particularly preferably 5.0 or less, from the viewpoint of further suppressing the deterioration of the film appearance quality. to be.

[8. Polyimide, polyamide, polyamideimide]

The optical film of the present invention contains at least one resin selected from the group consisting of polyimide resins and polyamide resins. The polyimide resin refers to a polymer containing a repeating structural unit containing an imide group (hereinafter sometimes referred to as a polyimide), and a polymer containing a repeating structural unit containing both an imide group and an amide group ( Hereinafter, at least one polymer selected from the group consisting of (may be described as polyamideimide) is shown. In addition, the polyamide resin represents a polymer containing a repeating structural unit containing an amide group.

It is preferable that the polyimide resin 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 resin may contain a repeating structural unit represented by two or more types of formula (10) from which G and/or A differ.

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

In formulas (10) and (11), G and G ¹ are each independently a tetravalent organic group, and preferably an organic group which may be substituted with 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) Alternatively, a group represented by formula (29) and a chain hydrocarbon group having 6 or less tetravalent carbon atoms are illustrated. Since it is easy to suppress the yellowness (YI value) of the optical film, among others, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula The group represented by (26) or formula (27) is preferable.

In equations (20) to (29),

* Represents a bond hand,

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

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

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

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

In equations (30) to (38),

* Represents a bond hand,

Z ¹ , Z ² and Z ³ are each independently a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) _2- , -C(CF ₃ ) ₂ -, -SO ₂ -or -CO-.

In one 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 position with respect to each ring of Z ¹ and Z ² and the bonding position of each ring with Z ² and Z ³ is a meta position or a para position with respect to each ring, respectively.

The polyimide resin is preferably a polyamideimide having at least a repeating structural unit represented by formula (10) and a repeating structural unit represented by formula (13) from the viewpoint of improving visibility (film appearance). Further, it is preferable that the polyamide resin has at least a repeating structural unit represented by formula (13).

In one embodiment of the present invention, the polyimide resin is a diamine and a tetracarboxylic acid compound (tetracarboxylic acid compound analogs such as an acid chloride compound and tetracarboxylic dianhydride), and, if necessary, Accordingly, a dicarboxylic acid compound (a dicarboxylic acid compound analog such as an acid chloride compound), a tricarboxylic acid compound (an acid chloride compound, a tricarboxylic acid compound analog such as a tricarboxylic acid anhydride), etc. are reacted (polycondensed) It is a condensed polymer obtained. The repeating structural unit represented by Formula (10) or Formula (11) is usually derived from a diamine and a tetracarboxylic acid compound. The repeating structural unit represented by formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

In one embodiment of the present invention, the polyamide resin is a condensation-type polymer obtained by reacting (polycondensation) 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 acid dianhydride; And aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic acid dianhydride. Tetracarboxylic acid compounds may be used alone or in combination of two or more. In addition to the dianhydride, the tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound.

Specific examples of the aromatic tetracarboxylic dianhydride include 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 2,2',3,3'-benzo Phenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4, 4'-diphenylsulfonetetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2, 2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA), 1,2-bis(2,3-di Carboxyphenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3 ,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride and 4,4'-(p-phenylenedioxy) ) Diphthalic acid dianhydride and 4,4'-(m-phenylenedioxy) diphthalic acid dianhydride. These can be used alone or in combination of two or more.

As the aliphatic tetracarboxylic dianhydride, a cyclic or acyclic aliphatic tetracarboxylic dianhydride can be mentioned. Cyclic aliphatic tetracarboxylic dianhydride is tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4- Cycloalkanetetracarboxylic dianhydrides such as cyclobutanetetracarboxylic dianhydride and 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3, 5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, and positional isomers thereof. These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride and the like, and these Alternatively, it can be used in combination of two or more. Further, a cyclic aliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used in combination.

Among the tetracarboxylic dianhydrides, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3, from the viewpoint of high transparency and low coloration properties, Preference is given to 5,6-tetracarboxylic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and mixtures thereof. Further, as the tetracarboxylic acid, a water adduct of an anhydride of the tetracarboxylic acid compound may be used.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and their related acid chloride compounds, acid anhydrides, and the like, and may be used in combination of two or more.

As a specific example, an anhydride of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; Phthalic anhydride and benzoic acid are a single bond, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or a compound connected with a phenylene group.

Examples of the dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and related acid chloride compounds and acid anhydrides thereof, and two or more of them may be used in combination. As specific examples thereof, terephthalic acid dichloride (terephthaloyl chloride (TPC)); Isophthalic acid dichloride; Naphthalenedicarboxylic acid dichloride; 4,4'-biphenyldicarboxylic acid dichloride; 3,3'-biphenyldicarboxylic acid dichloride; 4,4'-oxybis(benzoylchloride) (OBBC); A dicarboxylic acid compound of a chain hydrocarbon having 8 or less carbon atoms and two benzoic acids are linked with a single bond, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or a phenylene group And compounds.

As the diamine, an aliphatic diamine, an aromatic diamine, or a mixture thereof is mentioned, for example. In addition, in this embodiment, "aromatic diamine" represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group or other substituent may be included in a part of the structure. The aromatic ring may be a monocyclic ring or a condensed ring, and a benzene ring, a naphthalene ring, an anthracene ring, a fluorene ring and the like are exemplified, but are not limited thereto. Among these, it is preferable that the aromatic ring is a benzene ring. In addition, "aliphatic diamine" refers to a diamine in which an amino group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be included in a part of the structure.

Examples of aliphatic diamines include acyclic aliphatic diamines such as hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine, 4,4 And cyclic aliphatic diamines such as'-diaminodicyclohexylmethane. These can be used alone or in combination of two or more.

As aromatic diamine, for example, p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2 Aromatic diamines having one aromatic ring such as ,6-diaminonaphthalene; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-dia Minodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy) Benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-diaminodiphenylsulfone, bis (4-(4-aminophenoxy)phenyl) sulfone, bis (4-(3-amino) Phenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'- Dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine (2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (TFMB)), 4,4'-bis (4-aminophenoxy)biphenyl, 4,4'-diaminodiphenylether, 3,4'-diaminodiphenylether, 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- Aromatic diamines having two or more aromatic rings, such as amino-3-fluorophenyl) fluorene, are mentioned. These can be used alone or in combination of two or more.

Among the diamines, from the viewpoint of high transparency and low coloration, it is preferable to use at least one selected from the group consisting of aromatic diamines having a biphenyl structure. Consisting of 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4'-diaminodiphenyl ether It is more preferable to use at least one selected from the group, and even more preferably 2,2'-bis(trifluoromethyl)benzidine is used.

In the polyimide resin, after mixing each raw material such as the diamine, tetracarboxylic acid compound, tricarboxylic acid compound, and dicarboxylic acid compound by a conventional method such as stirring, the obtained intermediate is already It is obtained by imidation in the presence of a dehydration catalyst and, if necessary, a dehydrating agent. The polyamide resin is obtained by mixing each raw material such as the diamine and dicarboxylic acid compound by a conventional method, for example, stirring.

Although it does not specifically limit as an imidation catalyst used in an imidation process, For example, aliphatic amines, such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; Alicyclic amines (monocyclic) such as N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine; Alicyclic amines (polycyclic) such as azabicyclo[2.2.1]heptane, azabicyclo[3.2.1]octane, azabicyclo[2.2.2]octane, and azabicyclo[3.2.2]nonane; And 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4 -Aromatic amines, such as cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline, are mentioned.

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

In the mixing and imidization step of each raw material, the reaction temperature is not particularly limited, but is, for example, 15 to 350°C, preferably 20 to 100°C. The reaction time is also not particularly limited, but is, for example, about 10 minutes to 10 hours. If necessary, the reaction may be carried out in an inert atmosphere or under reduced pressure conditions. In addition, the reaction may be performed in a solvent, and examples of the solvent include those exemplified as the solvent used for preparing a varnish. After the reaction, the polyimide resin or polyamide resin is purified. As a purification method, for example, a poor solvent is added to the reaction solution to precipitate a resin by a reprecipitation method, dried to remove a precipitate, and if necessary, a method of washing and drying the precipitate with a solvent such as methanol. .

In addition, for the production of a polyimide resin, for example, you may refer to the manufacturing method described in Japanese Unexamined Patent Application Publication No. 2006-199945 or Japanese Unexamined Patent Application Publication No. 2008-163107. In addition, a commercially available product may be used as the polyimide resin, and specific examples thereof include Neopurim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd., KPI-MX300F manufactured by Kawamura Industrial Co., Ltd. and the like.

The weight average molecular weight of the polyimide resin or polyamide 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 larger the weight average molecular weight of the polyimide resin or the polyamide resin, the more likely it is to exhibit high bending resistance when formed into a film. For this reason, it is preferable that the weight average molecular weight is more than the said lower limit from a viewpoint of improving the bending resistance of an optical film. On the other hand, the lower the weight average molecular weight of the polyimide resin or the polyamide resin, the easier it is to lower the viscosity of the varnish and tend to improve the processability. Further, there is a tendency that the stretchability of the polyimide resin or the polyamide resin is easily improved. For this reason, it is preferable that the weight average molecular weight is below the said upper limit from a viewpoint of workability and stretchability. In addition, in the present application, the weight average molecular weight can be determined in terms of standard polystyrene by performing gel permeation chromatography (GPC) measurement, and can be calculated, for example, by the method described in Examples.

The imidation ratio of the polyimide resin is preferably 95 to 100%, more preferably 97 to 100%, still more preferably 98 to 100%, and particularly preferably 100%. From the viewpoint of the stability of the varnish and the mechanical properties of the obtained optical film, it is preferable that the imidation ratio is not less than the above lower limit. In addition, the imidation ratio can be calculated|required by IR method, NMR method, etc. From the above viewpoint, it is preferable that the imidation ratio of the polyimide resin contained in the varnish is within the above range.

In a preferred embodiment of the present invention, the polyimide resin or polyamide resin contained in the optical film of the present invention is, for example, a halogen atom such as a fluorine atom that can be introduced by the above fluorine-containing substituent. You may include. When the polyimide resin or the polyamide resin contains a halogen atom, it is easy to reduce the yellowness (YI value) while improving the elastic modulus of the optical film. When the elastic modulus of the optical film is high, it is easy to suppress the occurrence of wounds and wrinkles in the film, and when the yellowness of the optical film is low, it becomes easy to improve the transparency of the film. The halogen atom is preferably a fluorine atom. Preferred fluorine-containing substituents in order to contain a fluorine atom in the polyimide resin or polyamide resin include, for example, a fluoro group and a trifluoromethyl group.

The content of the halogen atom in the polyimide resin or polyamide resin is based on the mass of the polyimide resin or polyamide resin, preferably 1 to 40 mass%, more preferably 5 to 40 It is mass%, More preferably, it is 5-30 mass%. When the content of the halogen atom is 1% by mass or more, the elastic modulus at the time of film formation is further improved, the water absorption rate is lowered, the yellowness (YI value) is further reduced, and transparency is more easily improved. When the content of the halogen atom is 40% by mass or less, the synthesis tends to be easy.

In one embodiment of the present invention, the content of the polyimide resin and/or the polyamide resin in the optical film is based on the total mass of the optical film, preferably 40% by mass or more, more preferably Is 50 mass% or more, more preferably 70 mass% or more. It is preferable that the content of the polyimide-based resin and/or the polyamide-based resin is equal to or greater than the above lower limit from the viewpoint of easy to increase the bending resistance and the like. In addition, the content of the polyimide resin and/or the polyamide resin in the optical film is usually 100% by mass or less based on the total mass of the optical film.

[9. additive]

The optical film of the present invention may further contain an additive. As such an additive, a silica particle, an ultraviolet absorber, a whitening agent, a silica dispersing agent, an antioxidant, a pH adjuster, and a leveling agent are mentioned, for example.

(Silica particles)

The optical film of the present invention may further contain silica particles as an additive. The content of the silica particles is based on the total mass of the optical film, preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, preferably 60 parts by mass Below, it is more preferably 50 parts by mass or less, and still more preferably 45 parts by mass or less. In addition, the content of the silica particles can be combined by selecting an arbitrary lower limit value and an upper limit value from among these upper and lower limits. If the content of the silica particles is in the numerical range of the above upper and/or lower limits, in the optical film of the present invention, since the silica particles are difficult to aggregate and tend to be uniformly dispersed in the state of the primary particles, the optics of the present invention The decrease in visibility of the film can be suppressed.

The particle diameter of the silica particles is preferably 1 nm or more, more preferably 3 nm or more, more preferably 5 nm or more, particularly preferably 8 nm or more, preferably 30 nm or less, more preferably 28 It is nm or less, more preferably 25 nm or less, and particularly preferably 20 nm or less. The particle diameter of the silica particles can be combined by selecting an arbitrary lower limit value and an upper limit value from among these upper and lower limits. If the content of silica particles is in the numerical range of the above upper and/or lower limits, in the optical film of the present invention, since it is difficult to interact with light of a specific wavelength in white light, the visibility of the optical film of the present invention decreases. Can be suppressed. In this specification, the particle diameter of a silica particle represents an average primary particle diameter. The particle diameter of the silica particles in the optical film can be measured from imaging using a transmission electron microscope (TEM). The particle diameter of the silica particles before manufacturing the optical film (for example, before adding it to the varnish) can be measured by a laser diffraction particle size distribution meter. The method of measuring the particle diameter of the silica particles will be described in detail in Examples.

Examples of the form of the silica particles include silica sol in which silica particles are dispersed in an organic solvent or the like, and silica powder prepared by a gas phase method. Among these, silica sol is preferable from the viewpoint of workability.

The silica particles may be surface-treated, for example, silica particles obtained by substituting a solvent (more specifically, γ-butyrolactone, etc.) from a water-soluble alcohol-dispersed silica sol. The water-soluble alcohol is an alcohol having 3 or less carbon atoms per hydroxy group in one water-soluble alcohol molecule, and examples thereof include methanol, ethanol, 1-propanol, and 2-propanol. Although it depends on the affinity between the silica particles and the type of the polyimide polymer, in general, when the silica particles are surface-treated, the affinity with the polyimide polymer contained in the optical film is improved, and the dispersibility of the silica particles. Since this tends to improve, it is possible to suppress a decrease in visibility of the present invention.

(Ultraviolet absorber)

The optical film of this invention may further contain an ultraviolet absorber. For example, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzoate-based ultraviolet absorbers, and cyanoacrylate ultraviolet absorbers. These may be used independently and may use 2 or more types together. Preferred commercially available ultraviolet absorbers include, for example, Sumisorb (registered trademark) 340 manufactured by Sumika Chemtex Co., Ltd., Adecastab (registered trademark) LA-31 manufactured by ADEKA Co., Ltd., and BASF Japan Co., Ltd. Of Tinuvin (registered trademark) 1577, etc. are mentioned. 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, based on the mass of the optical film of the present invention.

(Brightening agent)

The optical film of this invention may further contain a whitening agent. The brightener can be added to adjust the color feeling, for example, when additives other than the brightener are added. Examples of the brightener include mono azo dyes, triarylmethane dyes, phthalocyanine dyes, and anthraquinone dyes. Among these, anthraquinone-based dyes are preferred. Preferred commercially available brighteners include, for example, Macrolex (registered trademark) Violet B, manufactured by Lanxes Corporation, Sumiplast (registered trademark) Violet B, manufactured by Sumika Chemtex, and Mitsubishi Diaresin (registered trademark) Blue G manufactured by Chemical Co., Ltd. can be mentioned. These may be used independently and may use 2 or more types together. The content of the whitening agent is preferably 5 ppm or more and 40 ppm or less, based on the mass of the optical film of the present invention.

[10. Manufacturing method of optical film]

The use of the optical film of the present invention is not particularly limited, and may be used in various applications. As described above, the optical film of the present invention may be a single layer or a laminate, and the optical film of the present invention may be used as it is, or may be used as a laminate with another film. Since the optical film of the present invention has excellent surface quality, it is useful as an optical film in an image display device or the like.

The optical film of the present invention is useful as a front plate of an image display device, particularly a front plate (window film) of a flexible display. A flexible display includes, for example, a flexible functional layer and the polyimide-based film which is superimposed on the flexible functional layer and functions as a front plate. That is, the front plate of the flexible display is disposed on the image viewer side of the flexible functional layer. This front plate has a function of protecting the flexible functional layer.

[11. Manufacturing method of optical film]

The optical film of the present invention is not particularly limited, but, for example, the following steps:

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

(b) a process of forming a coating film by applying a varnish to a substrate (application process), and

(c) Drying the applied liquid (coating film) to form an optical film (optical film forming process)

It can be produced by a method containing.

In the varnish preparation step, the resin is dissolved in a solvent, and the filler and other additives are added as necessary, followed by stirring and mixing to prepare a varnish. In the case of using silica as a filler, a silica sol in which a dispersion of silica sol containing silica is substituted with a solvent in which the resin is soluble, for example, a solvent used for preparing the following varnish may be added to the resin.

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

In the coating process, a varnish is applied on a substrate by a known coating method to form a coating film. Known coating methods include, for example, wire bar coating, reverse coating, roll coating such as gravure coating, die coating, comma coating, lip coating, spin coating, screen coating, fountain coating, di The ping method, the spray method, the casting method, etc. are mentioned.

In the optical film formation process, an optical film can be formed by drying the coating film and peeling it from the substrate. After peeling, you may perform a drying process of drying an optical film further. Drying of the coating film can be performed usually at a temperature of 50 to 350°C. If necessary, drying of the coating film may be performed under conditions of an inert atmosphere or reduced pressure.

Examples of the substrate include a metal-based, SUS plate, and a resin-based PET film, PEN film, other polyimide-based resin or polyamide-based resin film, cycloolefin-based polymer (COP) film, and acrylic film. Among them, from the viewpoint of excellent smoothness and heat resistance, a PET film, a COP film, and the like are preferable, and a PET film is more preferable from the viewpoint of adhesion and cost with an optical film.

<Optical laminate>

The optical layered product of the present invention has a hard coating layer (protective film) on at least one of the optical film of the present invention and the optical film. The optical laminate may further have an adhesive layer. The optical layered product of the present invention may be constituted by, for example, bonding the optical film and the hard coating layer of the present invention through an adhesive layer.

(Hard coating layer)

The thickness of the hard coating layer is not particularly limited, and may be, for example, 2 to 100 μm. When the thickness of the hard coating layer is within the above range, sufficient scratch resistance can be ensured, it is difficult to lower the bending resistance, and there is a tendency that the problem of curling due to cure shrinkage does not occur.

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

The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of the radical polymerizable compound may be a functional group capable of causing a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specifically, a vinyl group, (meta) Acryloyl group, etc. are mentioned. Further, when the radical polymerizable compound has two or more radical polymerizable groups, these radical polymerizable groups may be the same or different. The number of radically polymerizable groups in one molecule of the radical polymerizable compound is preferably 2 or more from the viewpoint of improving the hardness of the hard coat layer. As the radical polymerizable compound, from the viewpoint of high reactivity, a compound having a (meth)acryloyl group is preferably exemplified, and specifically, a polyfunctional compound having 2 to 6 (meth)acryloyl groups in one molecule Compounds called acrylate monomers or oligomers of hundreds to thousands of molecular weights having several (meth)acryloyl groups in a molecule called epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate And preferably one or more selected from epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate.

The cation polymerizable compound is a compound having a cation polymerizable group such as an epoxy group, an oxetanyl group, and a vinyl ether group. The number of cation polymerizable groups in one molecule of the cation polymerizable compound is preferably 2 or more, more preferably 3 or more from the viewpoint of improving the hardness of the hard coating layer.

In addition, as the cation polymerizable compound, a compound having at least one of an epoxy group and an oxetanyl group as a cation polymerizable group is particularly preferable. Cyclic ether groups, such as an epoxy group and an oxetanyl group, are preferable in that the shrinkage due to the polymerization reaction is small. In addition, the compound having an epoxy group among the cyclic ether groups has the advantage that compounds of various structures are readily available, does not adversely affect the durability of the obtained hard coating layer, and the affinity with the radical polymerizable compound is also easy to control. In addition, the oxetanyl group among the cyclic ether groups tends to have a higher degree of polymerization compared to the epoxy group, speeds up the network formation rate obtained from the cation polymerizable compound of the obtained hard coating layer, and is not reacted even in the region where the radical polymerizable compound is mixed. There is an advantage of forming an independent network without leaving a monomer in the film.

As a cationic polymerizable compound having an epoxy group, for example, polyglycidyl ether of a polyhydric alcohol having an alicyclic ring or a cyclohexene ring or a cyclopentene ring-containing compound is epoxidized with a suitable oxidizing agent such as hydrogen peroxide or peracid. The alicyclic epoxy resin obtained; Aliphatic epoxy resins such as polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof, polyglycidyl ester of an aliphatic long-chain polybasic acid, homopolymer of glycidyl (meth)acrylate, and a copolymer; Glycidyl ether prepared by reaction of bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or derivatives such as alkylene oxide adducts and caprolactone adducts, with epichlorohydrin , And novolac epoxy resin, and the like, and glycidyl ether type epoxy resin derived from bisphenols.

The hard coating composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cation polymerization initiator, a radical and a cation polymerization initiator, and the like, and are appropriately selected and used. Such a polymerization initiator is decomposed by at least one of active energy ray irradiation and heating to generate radicals or cation to advance radical polymerization and cation polymerization.

The radical polymerization initiator may be capable of releasing a substance for initiating radical polymerization by at least any of irradiation with active energy rays and heating. For example, examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.

As the active energy ray radical polymerization initiator, there are Type 1 type radical polymerization initiators that generate radicals by decomposition of molecules, and Type 2 type radical polymerization initiators that coexist with tertiary amines to generate radicals by hydrogen extraction type reaction. They are used alone or in combination.

The cation polymerization initiator should be capable of releasing a substance for initiating cation polymerization by at least any of irradiation with active energy rays and heating. As a cation polymerization initiator, an aromatic iodonium salt, an aromatic sulfonium salt, a cyclopentadienyl iron (II) complex, etc. can be used. These can initiate cation polymerization by either or both of irradiation with active energy rays or heating due to the difference in structure.

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

The hard coating composition may further include one or more selected from the group consisting of a solvent and an additive.

The solvent is one capable of dissolving or dispersing the polymerizable compound and the polymerization initiator, and as long as it is a solvent known as a solvent for the hard coating composition in the art, it can be used within a range that does not impair the effects of the present invention.

The additive may further include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

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

(Method of manufacturing an optical laminate having a circular polarizing plate)

An example of a method of manufacturing an optical laminate having a circular polarizing plate will be described. In the case of manufacturing an optical laminate having a circular polarizing plate including a polarizing layer/phase difference layer in this order, first, an optical film, a polarizing layer, and a retardation layer are formed on each. An optical film is produced by the method described above. For example, an alignment layer, a polarizer, and a protective layer are laminated in this order on a protective film as a substrate to form a polarizing layer. Further, the λ/4 phase difference plate and the positive C plate are bonded together using an adhesive to form a phase difference layer.

Next, the formed optical film, a polarizing layer, and a retardation layer are bonded together using an adhesive, and the optical laminated body which has a circular polarizing plate is manufactured. 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 is substantially 45° with respect to the slow axis (optical axis) of the retardation layer. In this way, the optical film / adhesive layer / polarizing layer (protective film / alignment layer / polarizer / protective layer) / adhesive layer / phase difference layer (λ/4 phase difference plate / positive C plate) having a circular polarizing plate stacked in this order An optical laminate can be manufactured.

The optical laminated body (hereinafter, also referred to as a laminated body) having the circular polarizing plate of the present invention contains the optical film of the present invention.

(Equation (39))

The laminate having the circular polarizing plate of the present invention, formula (39)

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

[In formula (39), transmission b* represents b* in the L*a*b* color system of light transmitted through the laminate, and reflection (SCE) b* reflects the laminate obtained by the SCE method. Represents b* in a wide L*a*b* color system]

Meets. The laminate having the circularly polarizing plate of the present invention has excellent visibility because, when the equation (39) is satisfied, the light transmission from the light source is large, and the reflection of external light becomes small, so that it approaches a neutral hue.

The numerical value (transmission b*-reflection (SCE) b*) of formula (39) is preferably 4.2 or more, more preferably 4.5 or more, and more preferably from the viewpoint of further improving the visibility of the laminate having a circular polarizing plate. It is preferably 5.0 or more, particularly preferably 6.5 or more.

(Transmission b*)

The transmission b* of the laminate having the circular polarizing plate is b* in the L*a*b* color system of the light transmitted through the laminate having the circular polarizing plate, and in this specification, the vertical plane of the laminate having the circular polarizing plate It refers to the b* value of the CIE 1976 L*a*b* color system of the transmitted light with respect to the incident light (white light) in a wavelength range of 380 to 780 nm incident from the direction. 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 laminate having a circular polarizing plate can be measured using an ultraviolet-visible near-infrared spectrophotometer, for example, by the method described in Examples.

(Reflection (SCE) b*)

The reflection (SCE) b* of the laminate having the circular polarizing plate is b* in the L*a*b* color system of the light reflected from the laminate having the circular polarizing plate obtained by the SCE method, and in the present specification, CIE 1976 L*a*b* of diffusely reflected light excluding regular reflected light among reflected light for incident light in a wavelength range of 380 to 780 nm, incident from a direction oblique at a predetermined angle from the plane of the laminate having a circular polarizing plate It refers to the b* value of the color system. 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 circular 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 circular polarizing plate is the b* in the L*a*b* color system of the light reflected from the circular polarizing plate obtained by the SCI method, and in this specification, it is determined from the vertical direction of the circular polarizing plate plane. It refers to the b* value of the CIE 1976 L*a*b* color system of reflected light (reflected light including regular reflected light) for incident light in a wavelength range of 380 to 780 nm incident from an angle oblique direction. The reflection (SCI) b* of the circular polarizing plate can be measured using a spectrophotometer, and for example, can be measured by the method described in Examples.

As a means for adjusting the transmission b*-reflection (SCE) b* in Equation (39) within a predetermined numerical range, for example, the transmission b*-reflection (SCE) b* of the optical film is expressed as Equation (1). Means for adjusting within the numerical range of and hue control by changing the composition of the optical film.

<Flexible image display device>

The flexible image display device of the present invention includes the optical laminate of the present invention. For example, the flexible image display device is composed of an optical laminate (a laminate for a flexible image display device) and an organic EL display panel, and a laminate for a flexible image display device is disposed on the viewing side of the organic EL display panel. , It is configured to be bent. The laminated body for a flexible image display device may further contain a window, a polarizing plate, and a touch sensor, and the stacking order thereof is arbitrary, but from the viewing side, a window, a polarizing plate, a touch sensor or a window, a touch sensor, and a polarizing plate are laminated in the order of It is desirable to have. If the polarizing plate is present on the visible side of the touch sensor, it is preferable that the pattern of the touch sensor is difficult to be recognized, and the visibility of the displayed image is improved. Each member may be laminated using an adhesive or an adhesive. In addition, a light shielding pattern formed on at least one surface of any layer of the window, the polarizing plate, and the touch sensor may be provided. The polarizing plate may be a circular polarizing plate.

(window)

The window is disposed on the visible side of the flexible image display device, and serves to protect other components from external impacts or environmental changes such as temperature and humidity. Conventionally, glass has been used as such a protective layer, but a window in a flexible image display device is not rigid and rigid like glass, but has a flexible characteristic. The window is made of a flexible transparent substrate, and may include a hard coating layer on at least one surface. The hard coating layer optionally included in the window has the same meaning as the hard coating layer of the optical laminate described above.

(Transparent material)

The transmittance of the transparent substrate in the visible region is usually 70% or more, and preferably 80% or more. As the transparent substrate, as long as it is a transparent polymer film, it can be used as long as the effect of the present invention is not impaired. Specifically, examples of the polymer film to be used include polyolefins such as polyethylene, polypropylene, polymethylpentene, norbornene or cycloolefin derivatives having monomer units containing cycloolefin, diacetyl cellulose, triacetyl cellulose, (Modified) celluloses such as propionyl cellulose, acrylics such as methyl methacrylate (co)polymers, polystyrenes such as styrene (co)polymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymerization Retention, ethylene-vinyl acetate copolymers, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyesters such as polycarbonate, polyarylate, polyamids such as nylon Films such as Drew, polyimide, polyamideimide, polyetherimide, polyethersulfone, polysulfone, polyvinyl alcohol, polyvinyl acetal, polyurethane, epoxy resin, etc. are mentioned. From the viewpoint of excellent transparency and heat resistance, preferably a polyamide, polyamideimide, polyimide, polyester, olefin, acrylic or cellulose film is mentioned. These polymers may be used alone or in combination of two or more. Such a film is used as unstretched or as a uniaxial or biaxially stretched film.

It is also preferable to disperse inorganic particles such as silica, organic fine particles, and rubber particles in the polymer film. In addition, a coloring agent such as a pigment or dye, a fluorescent whitening agent, a dispersant, a plasticizer, a heat stabilizer, a light stabilizer, an infrared absorber, an ultraviolet absorber, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like may be contained. The thickness of the transparent substrate is usually 5 to 200 μm, preferably 20 to 100 μm.

(Polarizer)

A polarizing plate, especially a circular polarizing plate, is a functional layer having a function of transmitting only a right or left circularly polarized component by laminating a λ/4 retardation plate on a linear polarizing plate. For example, external light is converted into right circularly polarized light, which is reflected by the organic EL panel to block external light that has become left circularly polarized light, and is used to suppress the influence of reflected light by transmitting only the light emission component of the organic EL to make the image easier to see. In order to achieve the circular polarization function, the absorption axis of the linear polarizing plate and the slow axis of the λ/4 retardation plate need to be 45° in theory, but are practically 45±10°. The linear polarizing plate and the λ/4 retardation plate do not necessarily need to be laminated adjacent to each other, and the relationship between the absorption axis and the slow axis may satisfy the above-described range. Although it is desirable to achieve complete circular polarization at all wavelengths, in practical use, it is not necessary to do so, and thus the circular polarizing plate in the present invention also includes an elliptically polarizing plate. It is also preferable to further increase the visibility in the state of wearing polarized sunglasses by laminating a λ/4 retardation film further on the viewing side of the linear polarizing plate to make the outgoing light circularly polarized.

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

The linear polarizer may be a film-type polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA)-based film. A dichroic dye such as iodine is adsorbed to the PVA-based film oriented by stretching or stretched in a state adsorbed by PVA, whereby the dichroic dye is oriented to exhibit polarization performance. In the production of the film-type polarizer, other steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying may be provided. The stretching and dyeing process may be performed by the 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 draw ratio is preferably 2 to 10 times.

Further, as another example of the polarizer, a liquid crystal coating type polarizer formed by applying a liquid crystal polarizing composition may be used. The liquid crystal polarizing composition may contain a liquid crystal compound and a dichroic dye compound. The liquid crystal compound should have a property that exhibits a liquid crystal state, and particularly, if it has a high-order alignment state such as a smectic phase, it is preferable because it can exhibit high polarization performance. Moreover, it is also preferable that a liquid crystal compound has a polymerizable functional group.

The dichroic dye is a dye that is oriented together with the liquid crystal compound to exhibit dichroism, and the dichroic dye itself may have liquid crystal properties or may have a polymerizable functional group. Any compound in the liquid crystal polarizing composition has a polymerizable functional group.

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

The circular polarizing plate may be a liquid crystal polarizing layer. The liquid crystal polarizing layer is produced by forming a liquid crystal polarizing layer by applying a liquid crystal polarizing composition on an alignment film.

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

The alignment layer can be produced, for example, by applying an alignment layer forming composition on a substrate and imparting alignment by rubbing, polarized light irradiation, or the like. In addition to the alignment agent, the alignment film forming composition may contain a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. As the aligning agent, for example, polyvinyl alcohol, polyacrylates, polyamic acids, and polyimides can be used. When applying photo-alignment, it is preferable to use an aligning agent containing a cinnamate group. The weight average molecular weight of the polymer used as the aligning agent may be about 10,000 to 1,000,000. The thickness of the alignment film is preferably 5 to 10,000 nm, more preferably 10 to 500 nm, from the viewpoint of alignment regulating force. The liquid crystal polarizing layer may be peeled off from the substrate, transferred, and laminated, or the substrate may be laminated as it is. It is also preferable that the substrate serves as a protective film, a retardation plate, or a transparent substrate for a window.

As the protective film, a transparent polymer film may be used, and materials and additives used for the transparent substrate can be used. A cellulose film, an olefin film, an acrylic film, and a polyester film are preferable. A coating-type protective film obtained by applying and curing a cation curing composition such as an epoxy resin or a radical curing composition such as an acrylate may be used. If necessary, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or dye, a fluorescent whitening agent, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like may be included. The thickness of the protective film may be 200 µm or less, and preferably 1 to 100 µm. When the thickness of the protective film is within the above range, the flexibility of the protective film is difficult to decrease. The protective film can also serve as a transparent substrate for a window.

The λ/4 retardation plate is a film that imparts a phase difference of λ/4 in a direction orthogonal to the traveling direction of incident light (in-plane direction of the film). The λ/4 retardation plate may be a stretched retardation plate manufactured by stretching a polymer film such as a cellulose film, an olefin film, or a polycarbonate film. If necessary, a phase difference adjuster, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or dye, a fluorescent whitening agent, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, etc. may be included. The thickness of the stretched retardation plate may be 200 µm or less, and preferably 1 to 100 µm. When the thickness is in the above range, there is a tendency that the flexibility of the film is difficult to decrease.

Further, as another example of the λ/4 retardation plate, a liquid crystal coating type retardation plate formed by applying a liquid crystal composition may be used. The liquid crystal composition includes a liquid crystal compound having a property of exhibiting a liquid crystal state such as nematic, cholesteric, and smectic. Any compound including a liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The liquid crystal coating type retardation plate may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coating type retardation plate can be produced by forming a liquid crystal retardation layer by coating and curing a liquid crystal composition on an alignment film, similarly to the substrate in the liquid crystal polarizing layer. The liquid crystal coating type retardation plate can be formed to have a thinner thickness compared to the stretched type retardation plate. The thickness of the liquid crystal polarizing layer may be usually 0.5 to 10 μm, preferably 1 to 5 μm. The liquid crystal coated retardation plate may be laminated by peeling and transferring from the substrate, or the substrate may be laminated as it is. It is also preferable that the substrate serves as a protective film, a retardation plate, or a transparent substrate for a window.

In general, the shorter the wavelength is, the larger the birefringence is, and the longer the longer wavelength, the smaller the birefringence is. In this case, since a phase difference of λ/4 cannot be achieved in the entire visible light region, an in-plane phase difference of 100 to 180 nm, preferably 130 to 150 nm, so as to be λ/4 in the vicinity of 560 nm with high visibility. It is often designed to be nm. It is preferable to use an inverse dispersion λ/4 retardation plate using a material having a birefringence wavelength dispersion characteristic opposite to that of the usual, since it can improve visibility. As such a material, it is also preferable to use those described in Japanese Unexamined Patent Application Publication No. 2010-30979, for example, in the case of an elongated retardation plate, and Japanese Unexamined Patent Publication No. 2007-232873.

In addition, as another method, a technique for obtaining a broadband λ/4 retardation plate by combining it with a lambda /2 retardation plate is also known (Japanese Laid-Open Patent Publication No. Hei 10-90521). The λ/2 retardation plate is also manufactured by the same material method as the λ/4 retardation plate. The combination of the stretched retardation plate and the liquid crystal coated retardation plate is arbitrary, but it is preferable to use a liquid crystal coated retardation plate in either case because the thickness can be reduced.

A method of laminating a positive C plate to the circular polarizing plate in order to increase visibility in an oblique direction is also known (Japanese Patent Laid-Open Publication No. 2014-224837). The positive C plate may be a liquid crystal coating type retardation plate or a stretch type retardation plate. The retardation in the thickness direction is usually -200 to -20 nm, preferably -140 to -40 nm.

(Touch sensor)

The touch sensor is used as an input means. As the touch sensor, various modes such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitance method have been proposed, and any method may be used. Among them, the electrostatic capacity method is preferable. The capacitive touch sensor is divided into an active area and an inactive area located at an outer portion of the active area. The active area is an area corresponding to an area (display unit) in which the screen is displayed on the display panel, and is an area where a user's touch is sensed, and the inactive area is an area corresponding to an area in which the screen is not displayed (non-display area) on the display device. . The touch sensor includes a substrate having a flexible characteristic; A sensing pattern formed in the active area of the substrate; It is formed in the non-active region of the substrate, and may include each sensing line for connecting to an external driving circuit through the sensing pattern and the pad portion. As the substrate having flexible properties, the same material as the transparent substrate for the window can be used. It is preferable that the substrate of the touch sensor has a toughness of 2,000 MPa% or more in terms of crack suppression of the touch sensor. More preferably, the toughness may be 2,000 to 30,000 MPa%. Here, toughness is defined as the area under the curve from the stress-strain curve (%) obtained through a tensile test of a polymer material to the point of failure.

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

The bridge electrode may be formed on the insulating layer by interposing an insulating layer on the sensing pattern, a bridge electrode may be formed on a substrate, and an insulating layer and a sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, or may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of them. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint of the first pattern and the bridge electrode, or may be formed in a layer structure covering the sensing pattern. In the latter case, the bridge electrode can connect the second pattern through a contact hole formed in the insulating layer. The touch sensor appropriately compensates for the difference in transmittance between the patterned area in which the pattern is formed and the non-patterned area in which the pattern is not formed, specifically, the difference in light transmittance caused by the difference in refractive indices in these areas. An optical control layer may be further included between the substrate and the electrode as a means, and the optical control layer may include an inorganic insulating material or an organic insulating material. The optical control layer may be formed by coating a photocurable composition including a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The refractive index of the optical control layer may be increased by the inorganic particles.

The photocurable organic binder may include, for example, a copolymer of each monomer such as an acrylate-based monomer, a styrene-based monomer, and a carboxylic acid-based monomer. The photocurable organic binder may be, for example, a copolymer containing different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit.

The inorganic particles may include, for example, zirconia particles, titania particles, alumina particles, and the like. The photocurable composition may further contain additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

(Adhesive layer (adhesive layer))

Each layer (window, polarizing plate, touch sensor) forming the laminate for a flexible image display device and film members (straight polarizing plate, λ/4 retardation plate, etc.) constituting each layer can be formed using an adhesive. Examples of adhesives include water-based adhesives, organic solvents, solvent-free adhesives, solid adhesives, solvent vaporizing adhesives, moisture curing adhesives, heat curing adhesives, anaerobic curing adhesives, active energy ray curing adhesives, curing agent mixture adhesives, heat melting adhesives, pressure sensitive adhesives. Any commonly used adhesive such as an adhesive (adhesive) or a rewet adhesive can be used. Among them, water-based solvent volatilization type adhesives, active energy ray-curable adhesives, and pressure-sensitive adhesives are well used. The thickness of the adhesive layer can be appropriately adjusted according to the required adhesion, etc., and is usually 0.01 to 500 µm, preferably 0.1 to 300 µm, and there are a plurality of laminates for the flexible image display device, but each thickness and pressure-sensitive adhesive used The types of may be the same or different.

Examples of the aqueous aqueous solvent volatilization adhesive include polyvinyl alcohol-based polymers, water-soluble polymers such as starch, ethylene-vinyl acetate-based emulsions, and styrene-butadiene-based emulsions, etc., as the main polymer. Can be used. In addition to water and the main polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be blended. In the case of bonding with the water-based aqueous solvent volatilization type adhesive, adhesion can be imparted by injecting the water-based aqueous solvent volatilization type adhesive between the adherend layers to bond the adherend layer and then drying. In the case of using the water-based aqueous solvent volatilization type adhesive, the thickness of the adhesive layer may be preferably 0.01 to 10 µm, more preferably 0.1 to 1 µm. When the water-based solvent volatilization adhesive is used for forming a plurality of layers, the thickness of each layer and the type of the adhesive may be the same or different.

The active energy ray-curable adhesive may be formed by curing an active energy ray-curable composition containing a reactive material that forms an adhesive layer by irradiating with an active energy ray. The active energy ray-curable composition may contain at least one polymer of a radical polymerizable compound and a cation polymerizable compound similar to the hard coating composition. The radical polymerizable compound is the same as the hard coating composition, and the same type of the hard coating composition can be used. The radical polymerizable compound used for the adhesive layer is preferably a compound having an acryloyl group. It is also preferable to include a monofunctional compound in order to lower the viscosity as an adhesive composition.

The cation polymerizable compound is the same as the hard coating composition, and the same type of the hard coating composition can be used. As the cationic polymerizable compound used in the active energy ray curing composition, an epoxy compound is particularly preferable. It is also preferable to include a monofunctional compound as a reactive diluent in order to lower the viscosity as an adhesive composition.

The active energy ray composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cation polymerization initiator, a radical and a cation polymerization initiator, and the like, and can be appropriately selected and used. Such a polymerization initiator is decomposed by at least one of active energy ray irradiation and heating to generate radicals or cation to advance radical polymerization and cation polymerization. Among the substrates of the hard coating composition, an initiator capable of initiating at least any of radical polymerization or cationic polymerization by irradiation with active energy rays can be used.

The active energy ray curing composition may further contain an ion scavenger, an antioxidant, a chain transfer agent, an adhesion imparting agent, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, a defoaming agent, a solvent, an additive, and a solvent. In the case of bonding with the active energy ray-curable adhesive, the active energy ray-curable composition is applied to any or both of the adhered layers and then bonded, and cured by irradiating active energy rays through the adhered layer or both adhered layers. By making it possible to bond. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer may be preferably 0.01 to 20 µm, more preferably 0.1 to 10 µm. When the active energy ray-curable adhesive is used for forming a plurality of layers, the thickness of each layer and the type of adhesive used may be the same or different.

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

(Shading pattern)

The light blocking pattern may be applied as at least a part of a bezel or a housing of the flexible image display device. The wiring arranged in the periphery of the flexible image display device is concealed by the light-shielding pattern to make it difficult to visually recognize, thereby improving the visibility of the image. The shading pattern may be in the form of a single layer or a multilayer. The color of the shading pattern is not particularly limited, and may have various colors such as black, white, and metallic colors. The shading pattern may be formed of a pigment for implementing color and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, or silicone. These may be used alone or as a mixture of two or more. The shading pattern may be formed by various methods such as printing, lithography, and inkjet. The thickness of the light shielding pattern is usually 1 to 100 µm, preferably 2 to 50 µm. In addition, it is also preferable to give a shape such as an inclination in the thickness direction of the light pattern.

Example

Hereinafter, the present invention will be described in more detail by examples. In the examples, "%" and "parts" mean mass% and mass parts unless otherwise specified. First, the evaluation method will be described.

<1. Measurement method>

(Reflection of optical film (SCE) a*, reflection (SCE) b*, reflection (SCI) a*, reflection (SCI) b*)

After cutting the optical film obtained in Examples and Comparative Examples into a size of 50 mm x 50 mm, it was bonded with black PET ("Kukkiri Mieru" manufactured by Tomoegawa Co., Ltd.), and a sample for reflective optical measurement Got it.

The hue of the SCE system (removal of regular reflection light) and the SCI system (including regular reflection light) of the obtained evaluation sample was measured with a spectrophotometer ("CM-3700A" manufactured by Konica Minolta Co., Ltd.). The measurement diameter is LAV: 8 mm in diameter, the measurement conditions are di: 8°, de: 8° (diffuse illumination, 8° light receiving), the measurement field of view is 2°, and a D65 light source is used as the light source. UV conditions were set to 100% Full. Here, hue refers to a* and b* in the CIE 1976 L*a*b* color space. In addition, reflection (SCE) a* and reflection (SCI) a* of the optical film were also measured under the same conditions as above.

(Reflection (SCE) b* and reflection (SCI) b* of a laminate with a circular polarizing plate)

The reflection (SCE) b* and reflection (SCI) b* of the laminate having a circular polarizing plate were measured in the same manner as the measurement method of an optical film, except that the measurement object was changed from an optical film to a laminate having a circular polarizing plate. . Further, in the same manner, reflection (SCE) a* and reflection (SCI) a* were also measured.

(Luminous transmittance Y of laminate with circular polarizing plate)

The luminous transmittance Y is a physical property value indicating the brightness of an object color in the XYZ color system. The luminous transmittance Y of the SCE system of the SCI system was measured using a spectrophotometer ("CM-3700A" manufactured by Konica Minolta Co., Ltd.).

(Transmission b* of optical film)

The optical films obtained in Examples and Comparative Examples were cut to a size of 50 mm x 50 mm, and transmission optical measurements were measured using a spectrophotometer ("CM-3700A" manufactured by Konica Minolta Co., Ltd.). The measurement diameter was LAV: 25.4 mm in diameter, and the measurement field was 2°. In addition, the D65 light source was used as the measurement light source, and the UV condition was 100% Full. Here, hue refers to a* and b* in the CIE 1976 L*a*b* color space.

(Transmission b* of laminate with circular polarizing plate)

Transmission b* of the laminated body having a circular 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 a laminate having a circular polarizing plate. In addition, in the same manner, the transmission a* of the laminate having the circular polarizing plate was also measured.

(Film thickness of optical film and adhesive layer)

Using a micrometer ("ID-C112XBS" made by Mitsutoyo), the film thickness of the optical film of 10 points or more was measured, and the average value was calculated. In the same manner, the thickness of the pressure-sensitive adhesive layer was measured, and the average value was calculated.

(Total light transmittance and haze of optical film)

The total light transmittance and haze of the optical film were measured in accordance with JIS K7361-1:1997 and JIS K 7136:2000, respectively, using a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Testing Instruments Co., Ltd. The measurement sample was prepared by cutting the optical films of Examples and Comparative Examples into a size of 30 mm x 30 mm.

(Yellowness of optical film)

The yellowness (Yellow Index: YI value) of the optical film was measured using an ultraviolet visible near-infrared spectrophotometer ("V-670" manufactured by Japan Spectroscopy Co., Ltd.). After performing background measurement without a sample, the optical films obtained in Examples and Comparative Examples were set in a sample holder, and transmittance was measured for light of 300 to 800 nm, and tristimulus values (X, Y, Z) Saved. From the obtained tristimulus value, based on the standard of ASTM D1925, the YI value was calculated based on the following formula.

YI=100×(1.2769X-1.0592Z)/Y

(Particle diameter of silica particles)

The particle diameter of the silica particles was calculated from the specific surface area measured value by the BET adsorption method according to JIS Z8830. The specific surface area of the powder obtained by drying the silica sol at 300°C was measured using a specific surface area measuring device ("Monosorb (registered trademark) MS-16" manufactured by Yuasa Ionics Co., Ltd.).

(Weight average molecular weight)

Gel permeation chromatography (GPC) measurement

(1) Pre-treatment method

A sample was dissolved in γ-butyrolactone (GBL) to obtain a 20% by mass solution, diluted 100 times with a DMF eluent, and filtered through a 0.45 µm membrane filter to obtain a measurement solution.

(2) Measurement conditions

Column: TSKgel SuperAWM-H x 2 + SuperAW 2500 x 1 (6.0 mm I.D. x 150 mm x 3)

Eluent: DMF (10 mmol of lithium bromide added)

Flow: 0.6 mL/min

Detector: RI detector

Column temperature: 40°C

Injection volume: 20 μL

Molecular weight standard: standard polystyrene

(Imidation rate)

The imidation ratio was calculated|required as follows by ¹ H-NMR measurement.

(1) Pre-treatment method

An optical film containing a polyimide polymer was dissolved in deuterated dimethyl sulfoxide (DMSO-d ₆ ) to obtain a 2% by mass solution, which was referred to as a measurement sample.

(2) Measurement conditions

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

Standard: DMSO-d ₆ (2.5ppm)

Sample temperature: room temperature

Integration count: 256 times

Relaxation time: 5 seconds

(3) Imidation ratio analysis method

(Imidation ratio of polyimide resin)

In the ¹ H-NMR spectrum obtained by the measurement sample containing a polyimide resin, an integrated value of the benzene-derived A proton of the benzene proton observed in the structure does not change before and after the already encoded were called _A Int. In addition, the integral value of the amide proton derived from the amic acid structure remaining in the observed polyimide resin was referred to as Int _B. From these integral values, the imidation ratio of the polyimide resin was determined based on the following formula.

Imidation rate (%) = 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 polyamic acid (imidation rate 0%).

(Imidation rate of polyamideimide resin)

In the ^polyamide-1 H-NMR spectrum obtained by the measurement sample containing the resins, of the observed benzene protons and derived from a structure that has already been changed before and after the encoding, derived from the amic acid structure remaining in the polyamide-imide resin The integral value of benzene proton C, which is not affected by the structure, was called Int _C. In addition, the integral value of benzene proton D, which is influenced by the structure derived from the structure derived from the amic acid structure remaining in the polyamideimide resin, derived from the structure that does not change before and after imidation among the observed benzene protons was referred to as Int _D. The β value was calculated from the obtained Int _C and Int _D by the following equation.

β= Int _D /Int _C

Next, the β value of the above formula and the imidation ratio of the polyimide resin of the above formula were determined for a plurality of polyamideimide resins, and the following correlations were obtained from these results.

Imidation rate (%)=k×β+100

In the above correlation equation, k is a constant.

Substituting β into the correlation formula, the imidation ratio (%) of the polyamideimide resin was obtained.

(Calculation of HSP value of resin)

The solubility of the polyamideimide resin 1 (PAI-1) in the solvent was evaluated. In a transparent container, 10 mL of a solvent having a known solubility parameter as shown in Table 1 (source: Polymer Handbook 4th Edition) and 10.1 g of a polyamideimide resin were added to prepare a mixed solution. The resulting mixture was subjected to ultrasonic treatment for 6 hours in total. The appearance of the mixed solution after the ultrasonic treatment was visually observed, and the solubility of the polyamideimide resin 1 in the solvent was evaluated based on the following evaluation criteria from the obtained observation results. Table 1 shows the evaluation results. In the same manner, polyamideimide resin 2 (PAI-2) and polyimide resin 1 (PI) were changed in the polyamideimide resin 1-solvent system. Except for the above, the solubility in the solvent was evaluated in the same manner.

(Evaluation standard)

1: The appearance of the mixed solution is cloudy.

0: The appearance of the mixed liquid is transparent.

From the evaluation result of the solubility of the obtained resin in a solvent, a Hansen sphere was created using the above described Hansen melting sphere method. The center coordinates of the obtained Hansen-gu were referred to as HSP values. The results are shown in Table 2.

(Calculation of HSP value of silica)

The solvent was removed from the silica sol 1, and silica 1 as a solid content was taken out. The dispersibility of the silica 1 in the solvent was evaluated. In a transparent container, 10 mL of a solvent having a known solubility parameter as shown in Table 3 (source: Polymer Handbook 4th edition) and 10.1 g of silica were added to prepare a mixed solution. The resulting mixture was subjected to ultrasonic treatment for 6 hours in total. The appearance of the mixed solution after ultrasonic treatment was visually observed, and the dispersibility of silica 1 in the solvent was evaluated based on the following evaluation criteria from the obtained observation results. Table 3 shows the evaluation results. In the same manner, methanol-dispersed silica sol ("MA-ST-L" manufactured by Nissan Chemical Industries, Ltd., primary particle diameter 20-25 nm), and methanol-dispersed silica sol (silicasol 2, primary particle diameter 10-12) Nm), in the silica 1-solvent system, the dispersibility in the solvent was evaluated in the same manner except that the kind of the silica sol as the raw material was changed.

(Evaluation standard)

1: The appearance of the mixed solution is cloudy.

0: The appearance of the mixed liquid is transparent.

From the evaluation results of the dispersibility of each silica dispersed in the silica sol in the solvent, a Hansen sphere was created using the above-described Hansen melting sphere method. The center coordinates of the obtained Hansen-gu were taken as the HSP value. The results are shown in Table 4.

(Resin-silica HSP value)

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

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

(Elastic modulus)

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

<2. Evaluation method>

(Evaluation of optical film feeding stability and film appearance)

Optical films of Examples and Comparative Examples were produced by roll-to-roll. The optical film was fed out from the roll (unwinding), and the state of the optical film when fed out was observed visually. From the observation results, feeding stability was evaluated based on the following evaluation criteria. From the superior one, in order, it is denoted by ◎, ○, △ and ×.

(Evaluation criteria for feeding out optical film)

(Double-circle): When feeding a film edge part from a roll, it can feed smoothly.

(Circle): When feeding out a film edge part from a roll, although a little jam is confirmed, it can feed out smoothly.

(Triangle|delta): When the film edge part is fed out from a roll, a jam is confirmed, but the film does not have a wound, and the film does not break.

X: When feeding out the end of the film from the roll, a jam is confirmed, a wound occurs in the film, or the film is cut.

(Evaluation of visibility of a laminate having a circular polarizing plate)

A laminate having a circular polarizing plate is installed on the surface of a reflector (aluminum plate, reflectance 97%), and the observer visually observes the laminate having a circular polarizing plate from an angle inclined 45° from the vertical direction of the plane of the laminate having a circular polarizing plate Observed. From the observation result, the visibility of the laminated body having a circular polarizing plate was evaluated based on the following evaluation criteria. From the superior one, in order, it is indicated by ○, △ and ×.

(Evaluation criteria for visibility of a laminate having a circular polarizing plate)

○: No color change on the reflector at 45° slope compared to the vertical direction

△: On the reflector, there is a slight color change at the 45° slope compared to the vertical direction.

X: On the reflecting plate, the color change at the 45° slope is large compared to the vertical direction.

(Evaluation of suppression of deterioration of film appearance quality)

Optical films of Examples and Comparative Examples were produced. Black paper was superimposed on the optical film, and the appearance of the optical film was visually observed from the optical film side. It was checked whether or not it had white rice (whether or not it was cloudy). Based on the following evaluation criteria from the observation result, suppression of the fall of the film appearance quality was evaluated.

(Evaluation criteria for suppression of film appearance quality deterioration)

◎(Very good): Transparent.

○ (Good): It is transparent, but has a slightly white taste.

× (poor): It is not transparent and has a white taste.

<3. Preparation of optical film>

[3-1. Preparation of polyimide polymer]

[Production Example 1: Polyimide resin 1]

A reaction vessel equipped with a silica gel tube, a stirring device, and a thermometer, and an oil bath were prepared in a separable flask. 75.52 g of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) and 2,2'-bis(trifluoromethyl)-4,4'- in the reaction vessel installed in the oil bath 54.44 g of diaminodiphenyl (TFMB) was added. While stirring the contents in the reaction vessel at 400 rpm, 519.84 g of N,N-dimethylacetamide (DMAc) was further added to the reaction vessel, and stirring was continued until the contents in the reaction vessel became a uniform solution. Subsequently, stirring was continued for an additional 20 hours while adjusting so that the temperature inside the container was in the range of 20 to 30°C using an oil bath, followed by reaction to produce 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 added to the reaction vessel to adjust the polymer concentration to 10% by weight based on the total weight of the contents in the reaction vessel. Further, 32.27 g of pyridine and 41.65 g of acetic anhydride were put into a reaction vessel, followed by stirring at room temperature for 10 hours to perform imidization. The polyimide varnish was taken out from the reaction vessel. The obtained polyimide varnish was dripped in methanol and reprecipitated. 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 imidation ratio was 98.6%.

(Production Example 2: Polyamideimide resin 1)

In a nitrogen gas atmosphere, a reaction vessel equipped with a stirring blade and an oil bath were prepared in a 1 L separable flask with a capacity. 45g (140.52mmol) of TFMB and 768.55g of DMAc were put into the reaction vessel installed in the oil bath. The contents in the reaction vessel were stirred at room temperature to dissolve TFMB in DMAc. Subsequently, 18.92 g (42.58 mmol) of 6FDA was further added into the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 3 hours. Thereafter, 4.19 g (14.19 mmol) of 4,4'-oxybis (benzoyl chloride) (OBBC), followed by 17.29 g (85.16 mmol) of terephthaloyl chloride (TPC) were added to the reaction vessel, and the inside of the reaction vessel was carried out. The contents were stirred at room temperature for 1 hour. Then, 4.63 g (49.68 mmol) of 4-methylpyridine and 13.04 g (127.75 mmol) of acetic anhydride were further added into the reaction vessel, and the contents of the reaction vessel were stirred at room temperature for 30 minutes. After stirring, the temperature inside the container was raised to 70° C. using an oil bath, maintained at 70° C., and the contents in the reaction container were further stirred for 3 hours to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, and put into a large amount of methanol in the form of a yarn, and a precipitate was deposited. The precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Subsequently, the precipitate was dried under reduced pressure at 100°C to obtain a polyamideimide resin. The weight average molecular weight of the polyamideimide resin was 400,000, and the imidation ratio was 98.8%.

(Production Example 3: Polyamideimide resin 2)

In a nitrogen gas atmosphere, a reaction vessel equipped with a stirring blade and an oil bath were prepared in a 1 L separable flask with a capacity. Into a reaction vessel installed in the oil bath, 45 g (140.52 mmol) of TFMB and 768.55 g of DMAc were added. The contents in the reaction vessel were stirred at room temperature while TFMB was dissolved in DMAc. Next, 6FDA 19.01 g (42.79 mmol) was further put into the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 3 hours. Then, 4.21 g (14.26 mmol) of OBBC, followed by 17.30 g (85.59 mmol) of TPC were put into the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 1 hour. Then, 4.63 g (49.68 mmol) of 4-methylpyridine and 13.04 g (127.75 mmol) of acetic anhydride were further added into the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 30 minutes. After stirring, the temperature inside the container was raised to 70°C using an oil bath, maintained at 70°C, and stirred for an additional 3 hours to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, and put into a large amount of methanol in a yarn shape to precipitate a precipitate. The precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Subsequently, the precipitate was dried under reduced pressure at 100°C to obtain a polyamideimide resin. The weight average molecular weight of the obtained polyamideimide resin was 365,000, and the imidation ratio was 98.9%.

[3-2. Preparation of silica particles]

(Production Example 4: Silica sol 1)

As a reaction vessel, a 1 L flask and a hot water bath were prepared. 442.6 g of methanol-dispersed silica sol (primary particle diameter 25 nm, silica solid content 30.5%) and 301.6 g of γ-butyrolactone were put into the reaction vessel provided in the bath. Using a hot water bath, the internal temperature of the vessel was set to 45°C, the pressure in the reaction vessel was maintained at 400 hPa using an evaporator, and the pressure in the reaction vessel was maintained at 250 hPa for 1 hour, and methanol was evaporated. Made it. Further, the pressure in the reaction vessel was set to 250 hPa, and the temperature inside the vessel was raised to 70°C, followed by heating for 30 minutes. As a result, γ-butyrolactone dispersed silica sol (silicasol 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)

Solvent substitution was carried out in the same manner as in Production Example 4, except that the primary particle diameter of the methanol-dispersed silica sol was changed to 10 nm and the silica solid content was changed to 22%, and γ-butyrolactone dispersion of 20% solid content Silica sol (silica sol 2) was obtained.

(Production Example 6: Silica sol 3)

Methanol-dispersed silica sol (primary particle diameter 25 nm, silica solid content 30.5%) was changed to methanol-dispersed silica sol (Nissan Chemical Industry Co., Ltd. "MA-ST-L", primary particle diameter 40-50 nm) Was subjected to solvent substitution in the same manner as in Production Example 4 to obtain 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 a UV absorber, and Sumiplast (registered trademark) violet B as a whitening agent were added, Varnish 1 was prepared so that the solid content was 10.2%.

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

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

The composition (type and/or content of components) shown in Table 6 was changed, the solvent to be substituted was changed from γ-butyrolactone to N,N-dimethylacetamide, and the solid content concentration of the resin was changed to 11.0%. Other than that, varnish 3 was prepared in the same manner as varnish 1. In addition, varnishes 2 and 4 to 8 were each prepared in the same manner as varnish 1 except for changing to the composition shown in Table 6 (kind and/or content of components).

[Example 1]

[3-4. Preparation of optical film]

The obtained varnish 1 was cast-molded on a PET film ("Cosmoshine (registered trademark) A4100" manufactured by Toyobo Corporation) to form a coating film. The conveyance speed of PET in casting casting was 0.3 m/min. Thereafter, 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 from the PET film. Thereafter, by heating with a tenter at 200° C. for 12 minutes while transversely stretching the coating film, a 51 µm-thick polyamideimide film 1 was obtained.

[Example 2]

Except having changed the film thickness of coating, it carried out similarly to Example 1, and obtained the polyamide-imide film 2 of 29 micrometers in thickness.

[Example 3]

Except having changed the varnish 1 to varnish 2, in the same manner as in Example 1, a 50 µm-thick polyamideimide film 3 was obtained.

[Example 4]

Except having changed the varnish 1 to varnish 3, in the same manner as in Example 1, a polyamideimide film 4 having a thickness of 49 μm was obtained.

[Example 5]

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

The appearances of the obtained polyamideimide films 1 to 6 and 9 and polyimide films 7 and 8 were visually observed, and the presence or absence of cloudiness was confirmed. The presence of 90,000 cloudiness of the polyamideimide film was confirmed, and the presence of cloudiness was not confirmed in films other than that.

The optical films of Examples 1 to 7 contained polyamideimide, satisfying the formula (1), and evaluation of their feeding stability was any of ◎, ○, and △. The optical films of Comparative Examples 1 to 2 contained polyamideimide, did not satisfy the formula (1), and the evaluation results of their feeding stability were all ×.

It is clear that the optical films of Examples 1 to 7 are superior in both feeding stability and film appearance than the optical films of Comparative Examples 1 to 2.

In addition, in the optical films of Examples 1-7, the three-dimensional distance Ra determined by the Hansen melting sphere method satisfies the formula (3), and the evaluation results of suppressing the decrease in the film appearance quality were all (good). In the optical film of Comparative Example 2, the three-dimensional distance Ra did not satisfy the formula (3), and the evaluation result of suppressing the decrease in the film appearance quality was x (bad). It represents butyl acrylate. MMA stands for methyl methacrylate. HEA stands for hydroxyethylacrylate. AA stands for acrylic acid. The amount of the crosslinking agent and the SC agent added is the mass per 100 parts of the monomer.

(Formation of adhesive layer 1)

The composition 1 for forming a pressure-sensitive adhesive layer was applied to the mold-releasing surface of the mold-releasing substrate (polyethylene terephthalate film, 38 mu m in thickness) using an applicator to form a coating layer. The coating layer was dried at 100° C. for 1 minute to form an adhesive layer 1. The thickness of the pressure-sensitive adhesive layer 1 was 25 µm.

Next, on the pressure-sensitive adhesive layer 1, another base material (polyethylene terephthalate film, 38 µm in thickness) subjected to a release treatment was bonded. Then, it was cured for 7 days under conditions of a temperature of 23°C 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 adhesive layer 1 were measured. Table 9 summarizes the measurement results.

In addition, in the case of laminating the pressure-sensitive adhesive layer below, after laminating the pressure-sensitive adhesive layer, the release-treated substrate was peeled.

(Formation of adhesive layer 2)

The pressure-sensitive adhesive layer 2 was formed in the same manner as the pressure-sensitive adhesive layer 1, except that the pressure-sensitive adhesive layer-forming composition 1 was changed to the pressure-sensitive adhesive layer-forming composition 2, and the pressure-sensitive adhesive layer-forming composition was applied so that the thickness of the pressure-sensitive adhesive layer became 5 μm. Formed. The elastic modulus and thickness of the pressure-sensitive adhesive layer 2 are summarized in Table 9.

[3-6. Manufacturing of polarizing plate]

(Preparation of composition for forming an orientation film)

Polymer 1 is a polymer having a photoreactive group composed of the following structural units.

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

(Formation of alignment film)

On the protective film (triacetyl cellulose: TAC), the composition for forming an alignment film was applied by a bar coating method to form a coating film. The coating film was dried at 80° C. for 1 minute. Next, using a UV irradiation device (SPOT CURE SP-7, manufactured by Ushio Electric Co., Ltd.) and a wire grid (Ushio Electric Co., Ltd. ``UIS-27132##''), exposure amount of 100 mJ/cm ² (365 nm standard) ) Conditions, the coating film was irradiated with polarized UV. Accordingly, an alignment film was formed on the protective film. The alignment film had alignment performance, and the thickness was 100 nm.

(Preparation of a composition for forming a polarizer)

(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 referred to as compound (6)) were used. .

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

(Dichroic pigment)

As the dichroic dye, an azo dye described in Examples of Japanese Unexamined Patent Application Publication No. 2013-101328 represented by the following formula (7), formula (8), and formula (9) was used.

(Preparation of a composition for forming a polarizer layer)

The composition for forming a polarizer layer includes 75 parts by mass of compound (5), 25 parts by mass of compound (6), 2.5 parts by mass of each of the azo dyes represented by the above formulas (7), (8), and (9) as dichroic dyes, polymerization 6 parts by mass of 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369, manufactured by BASF Japan) as an initiator, and a polyacrylate compound (BYK-361N) as a leveling agent , BYK-Chemie) 1.2 parts by mass was mixed with 400 parts by mass of toluene, and the obtained mixture was stirred at 80°C for 1 hour to prepare.

(Manufacture of polarizer)

On the formed alignment film, the 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. Then, it cooled to room temperature. Using the UV irradiation device, ultraviolet rays were irradiated to the coating film under conditions of a cumulative amount of light of 1200 mJ/cm ² (365 nm standard). Accordingly, a polarizer was 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 was applied to form a coating film. The coating film was dried for 3 minutes at a temperature of 80°C. Accordingly, a protective layer was formed on the polarizer. The thickness of the protective layer was 0.5 µm.

By the above, a protective film, an alignment film, a polarizer, and a polarizing layer laminated in the order of a protective layer were produced.

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

Each component shown below was mixed, and the obtained mixture was stirred at 80 degreeC for 1 hour, and the composition for λ/4 phase difference layer formation was obtained.

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)butan-1-one, manufactured by BASF Japan): 6 parts by mass

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

Solvent (cyclopentanone): 400 parts by mass

The composition for forming an alignment layer was applied onto the first base film (100 µm in thickness, polyethylene terephthalate film (PET)) by a bar coating method, and heated and dried in a drying oven at 80° C. for 1 minute. Polarized UV irradiation treatment was performed on the obtained dry film to form a second alignment film. Polarization UV treatment was performed on the condition that the accumulated light amount measured at a wavelength of 365 nm was 100 mJ/cm ² using the UV irradiation device. In addition, the polarization direction of polarized UV was performed so that it might be 45 degrees with respect to the absorption axis of a polarizing layer. In this way, a laminate consisting of the "first base film/second alignment film" was obtained. The thickness of the second alignment film was 100 nm.

A composition for forming a λ/4 retardation layer was applied on the second alignment film of the laminate consisting of the “first base film/second alignment film” by a bar coating method, followed by heating and drying in a drying oven at 120° C. for 1 minute, Cooled to room temperature. A retardation layer was formed by irradiating the obtained dry film with ultraviolet rays having a cumulative amount of light of 1000 mJ/cm ² (365 nm) using the UV irradiation device. The thickness of the obtained retardation layer was measured with a laser microscope (OLS3000, manufactured by Olympus Corporation) and found to be 2.0 µm. The phase difference layer was a λ/4 plate showing a phase difference value of λ/4 in the in-plane direction. In this way, a laminate made of "first base film/second alignment film/λ/4 retardation layer" was 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 phase difference layer formation was obtained.

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, BYK-Chemie company make): 0.5 weight part

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

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

Like the λ/4 retardation plate, the composition for forming an alignment layer was applied on a second base film (thickness 100 μm, polyethylene terephthalate film (PET)) by a bar coating method, and in a drying oven at 90° C. for 1 minute It dried by heating to form a 3rd alignment film. Thereafter, on the third alignment layer, a composition for forming a positive C phase difference layer was applied by a bar coating method, heated and dried in a drying oven at 90° C. for 1 minute, and then accumulated light quantity using the UV irradiation device in a nitrogen atmosphere. A positive C plate was formed by irradiating ultraviolet rays of 1000 mJ/cm ² (365 nm standard). The thickness of the obtained positive C plate was measured with a laser microscope (OLS3000 manufactured by Olympus Corporation) and found to be 1.8 µm.

After that, a phase difference layer was prepared by bonding the surface of the λ/4 phase difference plate on the opposite side of the first base film to the side from which the second base film was peeled off of the positive C plate using the pressure-sensitive adhesive layer 2.

The formed λ/4 retardation plate and the positive C plate both contained a layer cured in a state in which the polymerizable liquid crystal compound was oriented.

[3-7. Preparation of a laminate having a circular polarizing plate]

Using the polyamideimide film 1, the polarizing layer, the pressure-sensitive adhesive layer 1 and the pressure-sensitive adhesive layer 2, a laminate 1 was produced. The laminate 1 was provided with the polyamideimide film 1/adhesive layer 1/polarization layer (protective film/alignment film/polarizer/protective layer)/adhesive layer 2 in this order. On the opposite side to the protective film side in the polarizing layer, the surface from which the first base film of the retardation layer was peeled was bonded through the pressure-sensitive adhesive layer 2. The retardation layer is a layer in which a λ/4 retardation plate RWP and a positive C plate PosiC are laminated. Thereafter, the pressure-sensitive adhesive layer 1 was provided on the side opposite to the polarizing layer of the phase difference layer. Accordingly, a laminate 1 having a circular polarizing plate was produced. Laminate 1 is a polyamideimide film 1 / adhesive layer 1 / polarizing layer (protective film / alignment film / polarizer / protective layer) / adhesive layer 2 / phase difference layer (λ/4 retardation plate / positive C plate) / adhesive layer 1 Were provided in this order. Here, notation of the alignment layer in the phase difference layer is omitted.

In addition, in the bonding of the polarizing layer and the retardation layer, the absorption axis of the polarizing layer was substantially 45° with respect to the slow axis (optical axis) of the retardation layer, and the polarizing layer and the retardation layer were bonded through the pressure-sensitive adhesive layer 2.

About the laminated body which has a circular polarizing plate, optical characteristic values were measured and calculated. Specifically, transmission b*, transmission a*, and a*, b*, and Y of the reflection (SCE) system were measured. From the obtained transmission b*, reflection (SCE) b*, and reflection (SCI) 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 polyamide-imide film 5 to the front plate instead of the polyamide-imide film 1, it carried out similarly to Example 8, and produced the laminated body 2 which has a circular polarizing plate, and measured and calculated the optical characteristic value.

[Example 10]

Except having applied the polyimide film 7 to the front plate instead of the polyamideimide film 1, it carried out similarly to Example 8, and produced the laminated body 3 which has a circular polarizing plate, and measured and calculated the optical characteristic value.

[Comparative Example 3]

Except having applied the polyimide film 8 to the front plate instead of the polyamideimide film 1, it carried out similarly to Example 8, and produced the laminated body 4 which has a circular polarizing plate, and measured and calculated the optical characteristic value.

The laminates having the circular polarizing plates of Examples 8 to 10 satisfies the formula (39), and the evaluation of their visibility was either of? And ?. In addition, the laminated body having the circularly polarizing plates of Examples 8 to 10 also satisfied Expression (40).

The circular polarizing plate of Comparative Example 3 did not satisfy the formula (39), and the evaluation of the visibility was ×. In addition, the laminated body having the circular polarizing plate of Comparative Example 3 did not satisfy the formula (40) either.

It is clear that the laminated body having the circularly polarizing plate of Examples 8-10 is superior in visibility compared to the laminated body having the circularly polarizing plate of Comparative Example 3.

Claims (10)

An optical film containing at least one member selected from the group consisting of polyimide, polyamide and polyamideimide, wherein the formula (1)
0.04≤reflection (SCE) b*/reflection (SCI) b*≤1.5 ... (1)
[In formula (1), reflection (SCE) b* represents b* in the L*a*b* color system of the light reflected by the optical film obtained by the SCE method, and reflection (SCI) b* is the SCI method Indicates b* in L*a*b* color system of light reflected from the optical film determined by
To meet the optical film. The method of claim 1,
In addition to equation (2)
Reflection (SCE) a*/Reflection (SCI) a*≤2.5 ··· (2)
[In formula (2), reflection (SCE) a* represents a* in the L*a*b* color system of the light reflected by the optical film obtained by the SCE method, and reflection (SCI) a* is the SCI method Represents a* in L*a*b* color system of light reflected from the optical film obtained by
To meet the optical film. The method according to claim 1 or 2,
An optical film having a haze of 1% or less and a total light transmittance Tt of 85% or more. The method according to any one of claims 1 to 3,
An optical film further comprising silica particles. The method of claim 4,
The silica particles are silica particles obtained by solvent-substituted silica sol dispersed in a water-soluble alcohol. The method according to any one of claims 1 to 5,
An optical film further comprising an ultraviolet absorber. An optical laminate comprising the optical film according to any one of claims 1 to 6, and a hard coating layer on at least one surface of the optical film. A flexible image display device comprising the optical laminate according to claim 7. The method of claim 8,
A flexible image display device further provided with a circular polarizing plate. The method of claim 8 or 9,
A flexible image display device further comprising a touch sensor.