JP7390101B2 - Optical laminates and display devices - Google Patents

Description

The present invention relates to an optical laminate and a display device including the same.

A laminated optical element for use in liquid crystal display devices has been proposed (Patent Document 1).

Japanese Patent Application Publication No. 2001-337225

In recent years, development of foldable display devices has been progressing.

The present invention aims to provide a foldable optical laminate.

[1] A first protective layer, a polarizing layer, a first adhesive layer, a first retardation layer, a second adhesive layer, a second retardation layer, and a second protective layer are laminated in this order, and the thickness of the second protective layer is An optical laminate, wherein the ratio (A/B) of the thickness (A) of the first protective layer to (B) is 3.3 or less.
[2] The optical laminate according to [1], wherein the second protective layer has a modified toughness defined by the following formula (1) of 2300 MPa·% or more.
Modified toughness = maximum stress x maximum strain (1)
[However, maximum stress and maximum strain indicate the stress and strain at the point of failure in the stress-strain curve, respectively.]
[3] The optical laminate according to [1] or [2], wherein the first protective layer has a thickness of 10 μm to 200 μm.
[4] The optical laminate according to any one of [1] to [3], wherein the second protective layer has a thickness of 5 μm to 100 μm.
[5] The optical laminate according to any one of [1] to [4], wherein the first adhesive layer and/or the second adhesive layer has a thickness of 1 μm or more.
[6] A display device comprising the optical laminate according to any one of [1] to [5].

According to the present invention, a foldable display device can be provided.

1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. 1 is a schematic cross-sectional view of a laminate schematically showing a method for manufacturing a laminate of the present invention. 1 is a schematic cross-sectional view of a laminate schematically showing a method for manufacturing a laminate of the present invention. 1 is a schematic cross-sectional view of a laminate schematically showing a method for manufacturing a laminate of the present invention. 1 is a schematic cross-sectional view of a laminate schematically showing a method for manufacturing a laminate of the present invention. 1 is a schematic cross-sectional view of a laminate schematically showing a method for manufacturing a laminate of the present invention. FIG. 2 is a diagram schematically showing a method of evaluation testing in Examples.

Hereinafter, an optical laminate (hereinafter also referred to as an optical laminate) according to one embodiment of the present invention will be described with reference to the drawings.

<Optical laminate>
FIG. 1 shows a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The optical laminate 10 includes a first protective layer 11, a polarizing layer 12, a first adhesive layer 13, a first retardation layer 14, a second adhesive layer 15, a second retardation layer 16, and a second protective layer 17 in this order. It has a laminated structure and is made thinner by having a ratio (A/B) of the thickness (A) of the first protective layer 11 to the thickness (B) of the second protective layer 16 of 3.3 or less. It is bendable even though it is. "Boldable" means that good results can be obtained in a bending test with a bending curvature of 2.5R. In the optical laminate according to a preferred embodiment of the present invention, good results are obtained in a bending test with a bending curvature of 1R. Bending tests with bending curvatures of 2.5R and 1R are performed according to the method described in the Examples below.

The thickness of the optical laminate 10 may be, for example, 25 μm to 1000 μm, preferably 30 μm to 500 μm, and more preferably 35 μm to 200 μm. When the thickness of the optical laminate 10 is between 25 μm and 1000 μm, it tends to be easier to make the display device using the optical laminate 10 thinner.

Each layer constituting the optical laminate 10 will be described below.

[First protective layer]
The first protective layer 11 may be made of, for example, a resin film, and preferably made of a transparent resin film, from the viewpoint of making the display device foldable. The resin film may be a long roll-shaped resin film or a sheet-shaped resin film. A long roll-shaped resin film is preferred since it can be manufactured continuously. Examples of the resin constituting the resin film include polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic esters; polyacrylic esters; triacetyl cellulose, diacetyl cellulose, and Examples include cellulose esters such as cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyether ketone; polyphenylene sulfide; polyphenylene oxide; polyimide; polyamide; and plastics such as polyamideimide. Among these, cyclic olefin resins, cellulose ester base materials, polyimides, polyamides, and polyamideimides are preferred. The first protective layer 11 can be a layer that is incorporated into a display device without being peeled off.

The thickness of the resin film is preferably thinner from the viewpoint of making the optical laminate 10 thinner, but if it is too thin, it tends to be difficult to ensure impact resistance. The thickness of the resin film may be, for example, 10 to 200 μm, preferably 30 to 150 μm, and more preferably 50 to 100 μm.

The first protective layer 11 may be subjected to a hard coat treatment, an antireflection treatment, an antistatic treatment, or the like on the surface or both surfaces on which the polarizing layer is not formed.

(alignment film)
The first protective layer 11 may include an alignment film. The alignment film has an alignment regulating ability to align the polymerizable liquid crystal constituting the polarizing layer 12 formed on the first protective layer 11 in a desired direction.

The alignment film facilitates liquid crystal alignment of the polymerizable liquid crystal. The state of liquid crystal alignment, such as horizontal alignment, vertical alignment, hybrid alignment, and tilted alignment, changes depending on the properties of the alignment film and the polymerizable liquid crystal, and the combination thereof can be arbitrarily selected. For example, if the alignment film is a material that exhibits horizontal alignment as an alignment regulating force, the polymerizable liquid crystal can form horizontal alignment or hybrid alignment, and if the alignment film is a material that exhibits vertical alignment, the polymerizable liquid crystal can form vertical alignment. An oriented or tilted orientation can be formed. Expressions such as "horizontal" and "vertical" refer to the direction of the long axis of the oriented polymerizable liquid crystals with respect to the plane of the polarizing layer 12. For example, vertical alignment means that the long axis of the polymerizable liquid crystal is aligned in a direction perpendicular to the plane of the polarizing layer 12. Vertical here means 90°±20° with respect to the plane of the polarizing layer 12.

If the alignment film is made of an oriented polymer, the alignment regulating force can be adjusted arbitrarily by changing the surface condition and rubbing conditions, and if it is made of a photo-alignable polymer, it can be adjusted by changing the polarized light irradiation conditions. It is possible to arbitrarily adjust it by etc. Moreover, liquid crystal alignment can also be controlled by selecting physical properties such as surface tension and liquid crystallinity of the polymerizable liquid crystal.

The alignment film formed between the first protective layer 11 and the polarizing layer 12 is insoluble in the solvent used when forming the polarizing layer 12 on the alignment film, and is not soluble in solvent removal or liquid crystal. It is preferable that the material has heat resistance in heat treatment for orientation. Examples of the alignment film include an alignment film made of an oriented polymer, a photo alignment film, a groove alignment film, etc. When applied to a long roll-shaped resin film, the orientation direction can be easily controlled. A photo-alignment film is preferred.

The thickness of the alignment film may be, for example, in the range of 10 nm to 5000 nm, preferably in the range of 10 nm to 1000 nm, and more preferably in the range of 30 to 300 nm.

The oriented polymers used in the rubbed alignment film include polyamides and gelatins having amide bonds in the molecule, polyimides having imide bonds in the molecule, polyamic acid which is a hydrolyzate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, Examples include polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic esters. Among them, polyvinyl alcohol is preferred. These oriented polymers may be used alone or in combination of two or more.

When forming an oriented film made of an oriented polymer on a first protective layer made of a resin film, the oriented film is usually made of a composition in which the oriented polymer is dissolved in a solvent (hereinafter referred to as "oriented polymer composition"). ) on a resin film and removing the solvent, or by applying an oriented polymer composition on a resin film, removing the solvent, and rubbing (rubbing method).

The solvents include water; alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, Ester solvents such as propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; toluene and Examples include aromatic hydrocarbon solvents such as xylene, nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorinated hydrocarbon solvents such as chloroform and chlorobenzene; and the like. These solvents may be used alone or in combination of two or more.

The concentration of the oriented polymer in the oriented polymer composition may be within a range that allows the oriented polymer to be completely dissolved in the solvent, but it is preferably 0.1 to 20% by mass in terms of solid content with respect to the solution. .1 to 10% by mass is more preferable.

Commercially available alignment film materials may be used as they are as the alignment polymer composition. Examples of commercially available alignment film materials include Sunever (registered trademark) (manufactured by Nissan Chemical Industries, Ltd.) and Optomer (registered trademark) (manufactured by JSR Corporation).

Methods for applying the oriented polymer composition to the resin film include coating methods such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator methods, and printing methods such as flexography. For example, known methods such as When the polarizing plate of the present invention is manufactured by a roll-to-roll continuous manufacturing method, a printing method such as a gravure coating method, a die coating method, or a flexographic method is usually employed as the coating method.

By removing the solvent contained in the oriented polymer composition, a dry film of oriented polymer is formed. Examples of methods for removing the solvent include natural drying, ventilation drying, heating drying, and reduced pressure drying.

The rubbing method involves coating a resin film with an oriented polymer composition on a rotating rubbing roll wrapped with a rubbing cloth and annealing it to coat the oriented polymer film formed on the surface of the resin film. An example is a method of contacting.

A photo-alignment film is usually produced by coating a resin film with a composition containing a polymer having a photoreactive group or a monomer and a solvent (hereinafter also referred to as a "composition for forming a photo-alignment film"), and applying polarized light (preferably polarized light). Obtained by irradiating with UV). A photo-alignment film is more preferable in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the polarized light to be irradiated.

The photoreactive group refers to a group that produces liquid crystal alignment ability when irradiated with light. Specifically, it is one that induces the orientation of molecules by irradiation with light, or that causes a photoreaction that is the origin of the liquid crystal alignment ability, such as an isomerization reaction, a dimerization reaction, a photocrosslinking reaction, or a photodecomposition reaction. be. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferred in terms of excellent orientation. The photoreactive group capable of causing the above reaction is preferably one having an unsaturated bond, especially a double bond, such as a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C More preferably, the group has at least one selected from the group consisting of a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond).

Examples of the photoreactive group having a C═C bond include a vinyl group, a polyene group, a stilbene group, a stilbazole group, a stilbazolium group, a chalcone group, and a cinnamoyl group. A chalcone group and a cinnamoyl group are preferred from the viewpoint of easy control of reactivity and expression of alignment regulating force during photoalignment. Examples of the photoreactive group having a C=N bond include groups having structures such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N=N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and those having an azoxybenzene as a basic structure. Examples of the photoreactive group having a C═O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, and a halogenated alkyl group.

The solvent for the composition for forming a photo-aligned film is preferably one that dissolves the polymer and monomer having a photo-reactive group, and examples of the solvent include the solvents listed as the solvent for the above-mentioned alignment polymer composition. can be mentioned.

The content of the polymer or monomer having a photoreactive group in the composition for forming a photo-alignment film can be adjusted as appropriate depending on the type of polymer or monomer having the photo-reactive group and the thickness of the photo-alignment film to be produced. However, it is preferably 0.2% by mass or more, and particularly preferably in the range of 0.3 to 10% by mass. Further, a polymeric material such as polyvinyl alcohol or polyimide or a photosensitizer may be contained within the range where the properties of the photo-alignment film are not significantly impaired.

Examples of the method for applying the photo-alignment film-forming composition to the resin film include the same method as the method for applying the above-described alignment polymer composition to the resin film. Examples of the method for removing the solvent from the applied composition for forming a photo-alignment film include the same method as the method for removing the solvent from the alignment polymer composition.

In order to irradiate polarized light, polarized light can be irradiated directly onto a composition for forming a photo-alignment film coated on a resin film, etc., from which the solvent has been removed, or by irradiating polarized light from the resin film side. It may also be of a type in which the light is transmitted and irradiated. Moreover, it is particularly preferable that the polarized light is substantially parallel light. The wavelength of the polarized light to be irradiated is preferably in a wavelength range in which a polymer having a photoreactive group or a photoreactive group of a monomer can absorb light energy. Specifically, UV (ultraviolet light) having a wavelength in the range of 250 to 400 nm is particularly preferred. Examples of light sources used for polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF, with high-pressure mercury lamps, ultra-high pressure mercury lamps, and metal halide lamps being more preferable. These lamps are preferable because they emit a high intensity of ultraviolet light with a wavelength of 313 nm. Polarized light can be irradiated by passing the light from the light source through a suitable polarizer. As such a polarizer, a polarizing filter, a polarizing prism such as Glan-Thompson or Glan-Taylor, or a wire grid type polarizer can be used.

Note that by performing masking when performing rubbing or polarized light irradiation, it is also possible to form a plurality of regions (patterns) in which the directions of liquid crystal alignment are different.

A groove alignment film is a film having an uneven pattern or a plurality of grooves on its surface. When liquid crystal molecules are placed on a film having a plurality of linear grooves arranged at equal intervals, the liquid crystal molecules are aligned in the direction along the grooves.

The groove alignment film can be obtained by exposing the surface of a photosensitive polyimide film to light through an exposure mask having pattern-shaped slits, followed by development and rinsing to form a concavo-convex pattern, and by using a plate with grooves on the surface. A method in which a layer of uncured UV curable resin is formed on a shaped master, the resin layer is transferred to a resin film, and then cured, and a film of uncured UV curable resin formed on the resin film is coated with multiple layers. Examples include a method in which a roll-shaped master disk having grooves is pressed against the surface to form irregularities, and then hardened. Specific examples include the methods described in JP-A-6-34976 and JP-A-2011-242743.

In order to obtain alignment with little alignment disturbance, the width of the convex portion of the groove alignment film is preferably 0.05 μm to 5 μm, the width of the concave portion is preferably 0.1 μm to 5 μm, and the width of the convex portion of the groove alignment film is preferably 0.1 μm to 5 μm. The depth is preferably 2 μm or less, and preferably 0.01 μm to 1 μm or less.

[Polarizing layer]
The polarizing layer 12 is not particularly limited as long as it is a layer containing one or more polymerizable liquid crystal compounds [hereinafter also referred to as polymerizable liquid crystals (a)] and a dichroic dye. When the polarizing layer 12 has polarization characteristics in the plane direction of the optical laminate 10, the dichroic dye and the polymerizable liquid crystal (a) are aligned horizontally with respect to the plane of the optical laminate 10, and the polymerizable liquid crystal (a) If the polarizing layer 20 has polarizing properties in the thickness direction of the optical laminate 10, the dichroic dye and the polymerizable liquid crystal (a) are aligned perpendicularly to the plane of the optical laminate 10. The polymerizable liquid crystal (a) may be cured in this state. The polarizing layer 12 is preferably a coating layer, and may be, for example, a cured product of composition (A) described below.

The polarizing layer 12 may be, for example, in the range of 0.5 to 10 μm, preferably in the range of 1 to 8 μm, and more preferably in the range of 1.5 to 5 μm.

The polarizing layer 12 is formed by applying a polarizing layer forming composition (hereinafter also referred to as composition (A)) containing, for example, one or more polymerizable liquid crystals (a) and a dichroic dye to a first protective layer or an alignment film. It can be formed by coating the polymerizable liquid crystal (a) on top and polymerizing the polymerizable liquid crystal (a) in the resulting coating film.

(Polymerizable liquid crystal)
The polymerizable liquid crystal (a) is a compound that has a polymerizable group and has liquid crystallinity. A polymerizable group means a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by active radicals, acids, etc. generated from a photopolymerization initiator, which will be described later. Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, and the like. Among these, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferred, and acryloyloxy group is more preferred. The liquid crystal may be either thermotropic liquid crystal or lyotropic liquid crystal, but thermotropic liquid crystal is preferable when mixed with a dichroic dye described below.

When the polymerizable liquid crystal (a) is a thermotropic liquid crystal, it may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase or a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase. When exhibiting a polarizing function as a cured film through a polymerization reaction, the liquid crystal state exhibited by the polymerizable liquid crystal (a) is preferably a smectic phase, and a higher-order smectic phase is more preferable from the viewpoint of high performance. . Among them, higher-order smectic liquid crystal compounds forming smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, smectic K phase or smectic L phase are used. More preferred are higher-order smectic liquid crystal compounds that form a smectic B phase, smectic F phase, or smectic I phase. When the liquid crystal phase formed by the polymerizable liquid crystal (a) is one of these higher-order smectic phases, a polarizing layer with higher polarizing performance can be manufactured. In addition, a polarizing layer having such high polarizing performance can obtain a Bragg peak derived from a higher-order structure such as a hexatic phase or a crystal phase in X-ray diffraction measurement. The Bragg peak is a peak derived from the periodic structure of molecular orientation, and a film having a periodic interval of 3 to 6 Å can be obtained. The polarizing layer of the present invention preferably contains a polymer of the polymerizable liquid crystal (a), which is polymerized in a smectic phase state, from the viewpoint of obtaining higher polarization properties.

Specific examples of such compounds include compounds represented by the following formula (I) (hereinafter also referred to as compound (I)). The polymerizable liquid crystal (a) may be used alone or in combination of two or more.

［式（Ｉ）中、
Ｘ^１、Ｘ^２およびＸ^３は、それぞれ独立に、２価の芳香族基または２価の脂環式炭化水素基を表し、ここで、該２価の芳香族基または２価の脂環式炭化水素基に含まれる水素原子は、ハロゲン原子、炭素数１～４のアルキル基、炭素数１～４のフルオロアルキル基、炭素数１～４のアルコキシ基、シアノ基またはニトロ基に置換されていてもよく、該２価の芳香族基または２価の脂環式炭化水素基を構成する炭素原子が、酸素原子または硫黄原子または窒素原子に置換されていてもよい。ただし、Ｘ^１、Ｘ^２およびＸ^３のうち少なくとも１つは、置換基を有していてもよい１，４－フェニレン基または置換基を有していてもよいシクロヘキサン－１，４－ジイル基である。
Ｙ^１、Ｙ^２、Ｗ^１およびＷ^２は、互いに独立に、単結合または二価の連結基である。
Ｖ^１およびＶ^２は、互いに独立に、置換基を有していてもよい炭素数１～２０のアルカンジイル基を表し、該アルカンジイル基を構成する－ＣＨ_２－は、－Ｏ－、－Ｓ－または－ＮＨ－に置き換わっていてもよい。
Ｕ^１およびＵ^２は、互いに独立に、重合性基または水素原子を表し、少なくとも１つは重合性基である。］

[In formula (I),
X ¹ , X ² and X ³ each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group; The hydrogen atom contained in the hydrocarbon group is substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group. The carbon atoms constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom. However, at least one of X ¹ , X ² and X ³ is a 1,4-phenylene group which may have a substituent or a cyclohexane-1,4-diyl group which may have a substituent. It is.
Y ¹ , Y ² , W ¹ and W ² are each independently a single bond or a divalent linking group.
V ¹ and V ² each independently represent an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and -CH ₂ - constituting the alkanediyl group is -O-, - It may be replaced with S- or -NH-.
U ¹ and U ² each independently represent a polymerizable group or a hydrogen atom, and at least one is a polymerizable group. ]

In compound (I), at least one of X ¹ , X ² and X ³ is a 1,4-phenylene group which may have a substituent, or a cyclohexane-1 which may have a substituent. ,4-diyl group. In particular, X ¹ and X ³ are preferably cyclohexane-1,4-diyl groups which may have substituents, and the cyclohexane-1,4-diyl group is trans-cyclohexane-1,4-diyl. More preferably, it is a 1,4-diyl group. When it contains a trans-cyclohexane-1,4-diyl group structure, it tends to exhibit smectic liquid crystallinity. In addition, the optional substituents of the 1,4-phenylene group which may have a substituent or the cyclohexane-1,4-diyl group which may have a substituent include a methyl group, Examples include alkyl groups having 1 to 4 carbon atoms such as ethyl and butyl groups, cyano groups, and halogen atoms such as chlorine and fluorine atoms. Preferably it is unsubstituted.

Y ¹ and Y ² each independently represent a single bond, -CH ₂ CH ₂ -, -CH ₂ O-, -COO-, -OCO-, -N=N-, -CR ^a =CR ^b -, - C≡C- or -CR ^a =N- is preferred, and R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. It is more preferable that Y ¹ and Y ² are -CH ₂ CH ₂ -, -COO-, -OCO-, or a single bond, and X ¹ , X ² and X ³ all represent a cyclohexane-1,4-diyl group. If not included, it is more preferable that Y ¹ and Y ² are bonded in different ways. When Y ¹ and Y ² have different bonding methods, smectic liquid crystallinity tends to occur easily.

W ¹ and W ² are preferably a single bond, -O-, -S-, -COO-, or OCO-, and more preferably a single bond or -O-, independently of each other.

Examples of the alkanediyl group having 1 to 20 carbon atoms represented by V ¹ and V ² include methylene group, ethylene group, propane-1,3-diyl group, butane-1,3-diyl group, butane-1,4 -diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, decane-1,10-diyl group, tetradecane Examples include -1,14-diyl group and icosane-1,20-diyl group. V ¹ and V ² are preferably alkanediyl groups having 2 to 12 carbon atoms, more preferably linear alkanediyl groups having 6 to 12 carbon atoms. A linear alkanediyl group having 6 to 12 carbon atoms improves crystallinity and tends to exhibit smectic liquid crystallinity.

Examples of optional substituents on the optionally substituted alkanediyl group having 1 to 20 carbon atoms include a cyano group and halogen atoms such as chlorine and fluorine atoms. , is preferably unsubstituted, and more preferably is an unsubstituted linear alkanediyl group.

Both U ¹ and U ² are preferably polymerizable groups, and more preferably both are photopolymerizable groups. A polymerizable liquid crystal compound having a photopolymerizable group can be polymerized under lower temperature conditions than a thermally polymerizable group, and therefore is advantageous in that a polymer can be formed in a state where the liquid crystal has a higher degree of order.

The polymerizable groups represented by U ¹ and U ² may be different from each other, but are preferably the same. Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, and the like. Among these, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferred, and methacryloyloxy group or acryloyloxy group is more preferred.

Examples of such polymerizable liquid crystal compounds include the following.

Among the exemplified compounds, formula (1-2), formula (1-3), formula (1-4), formula (1-6), formula (1-7), formula (1-8), formula At least one selected from the group consisting of compounds represented by (1-13), formula (1-14) and formula (1-15) is preferred.

The exemplified compounds (I) can be used alone or in combination for the polarizing layer 12. Furthermore, when two or more types of polymerizable liquid crystals (a) are combined, it is preferable that at least one type is compound (I), and it is more preferable that two or more types are compound (I). By combining two or more types of polymerizable liquid crystals (a), it may be possible to temporarily maintain liquid crystallinity even at temperatures below the liquid crystal-crystal phase transition temperature. The mass ratio when combining two types of polymerizable liquid crystals (a) is usually 1:99 to 50:50, preferably 5:95 to 50:50, more preferably 10:90 to 50. :50.

Compound (I) is described, for example, in Lub et al. Recl. Trav. Chim. It is produced by a known method described in Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156.

The content ratio of the polymerizable liquid crystal (a) in the polarizing layer 12 is usually 50 to 99.5 parts by mass, preferably 50 to 99.5 parts by mass, based on 100 parts by mass of the solid content of the composition (A) forming the polarizing layer 12. The amount is 60 to 99 parts by weight, more preferably 70 to 98 parts by weight, and still more preferably 80 to 97 parts by weight. If the content of the polymerizable liquid crystal is within the above range, the orientation tends to be high. Here, the solid content refers to the total amount of components excluding the solvent from the composition (A).

(dichroic dye)
A dichroic dye refers to a dye that has a property that the absorbance in the long axis direction of the molecule is different from the absorbance in the short axis direction. The dichroic dye preferably has a property of absorbing visible light, and more preferably has a maximum absorption wavelength (λMAX) in the range of 380 to 680 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, among which azo dyes are preferred. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, with bisazo dyes and trisazo dyes being preferred. Dichroic dyes may be used alone or in combination, but in order to obtain absorption in the entire visible light range, it is preferable to combine three or more types of dichroic dyes, and more preferably to combine three or more types of azo dyes. preferable.

Examples of the azo dye include a compound represented by formula (II) (hereinafter also referred to as "compound (II)").
T ¹ -A ¹ (-N=NA ² ) _p -N=NA ³ -T ² (II)
[In formula (II),
A ¹ and A ² and A ³ each independently represent a 1,4-phenylene group that may have a substituent, a naphthalene-1,4-diyl group, or a divalent group that may have a substituent. represents a heterocyclic group, and T ¹ and T ² are electron-withdrawing groups or electron-emitting groups, and are located at substantially 180° with respect to the azo bond plane. p represents an integer from 0 to 4. When p is 2 or more, each A ² may be the same or different from each other. -N=N- bonds are -C=C-, -COO-, -NHCO- in the range that shows absorption in the visible region. -N=CH- bond may be substituted. ]

The optional substituents of the 1,4-phenylene group, naphthalene-1,4-diyl group, and divalent heterocyclic group in A ¹ , A ² , and A ³ include methyl group, ethyl group, butyl group, etc. Alkyl group having 1 to 4 carbon atoms; Alkoxy group having 1 to 4 carbon atoms such as methoxy group, ethoxy group and butoxy group; Fluorinated alkyl group having 1 to 4 carbon atoms such as trifluoromethyl group; Cyano group; Nitro group ; Halogen atoms such as chlorine atoms and fluorine atoms; Substituted or unsubstituted amino groups such as amino groups, diethylamino groups, and pyrrolidino groups (substituted amino groups refer to amino groups having one or two alkyl groups having 1 to 6 carbon atoms; group, or an amino group in which two substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms. An example of an unsubstituted amino group is -NH ₂ ). Note that examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, and a hexyl group. Examples of the alkanediyl group having 2 to 8 carbon atoms include ethylene group, propane-1,3-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, and pentane-1,5-diyl group. , hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, and the like. In order to incorporate it into a highly ordered liquid crystal structure such as a smectic liquid crystal, A ¹ , A ² and A ³ are unsubstituted or 1,4-phenylene groups in which hydrogen is substituted with a methyl group or a methoxy group, or a divalent is preferably a heterocyclic group, and p is preferably 0 or 1. Among them, p is 1 and at least two of the three structures A ¹ , A ² and A ³ are 1,4-phenylene groups, which provides both ease of molecular synthesis and high performance. More preferred.

Examples of the divalent heterocyclic group include groups obtained by removing two hydrogen atoms from quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. When A ² is a divalent heterocyclic group, a structure in which the molecular bond angle is substantially 180° is preferable, and specifically, benzothiazole, benzimidazole, benzoxazole in which two 5-membered rings are fused structure is more preferred.

T ¹ and T ² are an electron-withdrawing group or an electron-emitting group, and preferably have different structures, such that T ¹ is an electron-withdrawing group and T ² is an electron-releasing group, or T ¹ is an electron-releasing group and T ^{2 is} an electron-withdrawing group. It is more preferable that the relationship is as follows. Specifically, T ¹ and T ² each independently represent one or more alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, cyano groups, nitro groups, alkyl groups having 1 to 6 carbon atoms, or An amino group having two amino groups, an amino group in which two substituted alkyl groups bond to each other to form an alkanediyl group having 2 to 8 carbon atoms, or a trifluoromethyl group are preferable, and among these, highly ordered such as smectic liquid crystals are preferable. In order to be included in the liquid crystal structure, the structure must have a smaller excluded volume of molecules, so alkyl groups with 1 to 6 carbon atoms, alkoxy groups with 1 to 6 carbon atoms, cyano groups, and An amino group having one or two alkyl groups having 1 to 6 carbon atoms, or an amino group in which two substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms is preferred.

Examples of such azo dyes include the following.

In formulas (2-1) to (2-6),
B ¹ to B ²⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (substituted amino group and (The unsubstituted amino group is defined as above), represents a chlorine atom or a trifluoromethyl group. From the viewpoint of obtaining high polarization performance, B ² , B ⁶ , B ⁹ , B ¹⁴ , B ¹⁸ , and B ¹⁹ are preferably hydrogen atoms or methyl groups, and more preferably hydrogen atoms.
n1 to n4 each independently represent an integer of 0 to 3.
When n1 is 2 or more, the plurality of ^B2s may be the same or different,
When n2 is 2 or more, the plurality of ^B6s may be the same or different,
When n3 is 2 or more, the plurality of ^B9s may be the same or different,
When n4 is 2 or more, the plurality of ^B14s may be the same or different.

The anthraquinone dye is preferably a compound represented by formula (2-7).

[In formula (2-7),
R ¹ to R ⁸ each independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.
R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

The oxazine dye is preferably a compound represented by formula (2-8).

[In formula (2-8),
R ⁹ to R ¹⁵ each independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.
R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

The acridine dye is preferably a compound represented by formula (2-9).

[In formula (2-9),
R ¹⁶ to R ²³ each independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.
R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

In formula (2-7), formula (2-8) and formula (2-9), the alkyl group having 1 to 4 carbon atoms represented by R ^x includes methyl group, ethyl group, propyl group, butyl group. , pentyl group, and hexyl group, and examples of the aryl group having 6 to 12 carbon atoms include phenyl group, tolyl group, xylyl group, and naphthyl group.

The cyanine dye is preferably a compound represented by formula (2-10) or a compound represented by formula (2-11).

ｎ５は１～３の整数を表す。］ [In formula (2-10),
D ¹ and D ² each independently represent a group represented by any one of formulas (2-10a) to (2-10d).

n5 represents an integer from 1 to 3. ]

ｎ６は１～３の整数を表す。］ [In formula (2-11),
D ³ and D ⁴ each independently represent a group represented by any one of formulas (2-11a) to (2-11h).

n6 represents an integer from 1 to 3. ]

From the viewpoint of obtaining good light absorption characteristics, the content of the dichroic dye (or the total amount when multiple types are included) is usually 0.1 to 30 parts by mass per 100 parts by mass of the polymerizable liquid crystal (a). parts, preferably 1 to 20 parts by weight, more preferably 3 to 15 parts by weight. If the content of the dichroic dye is less than this range, light absorption will be insufficient and sufficient polarization performance will not be obtained, and if it is more than this range, the alignment of liquid crystal molecules may be inhibited.

[First adhesive layer]
The optical laminate 10 has a first adhesive layer 13 between the polarizing layer 12 and the first retardation layer 14 . The first adhesive layer 13 can be formed from an adhesive, an adhesive, or a combination thereof. The first adhesive layer 13 is usually one layer, but may be two or more layers. The first adhesive layer 13 may be formed in contact with the polarizing layer 12 or the first retardation layer 14 .

As the adhesive, (meth)acrylic adhesive, styrene adhesive, silicone adhesive, rubber adhesive, urethane adhesive, polyester adhesive, epoxy copolymer adhesive, etc. can be used. can.

As the adhesive, for example, one or a combination of two or more of water-based adhesives, active energy ray-curable adhesives, pressure-sensitive adhesives, etc. can be used. Examples of water-based adhesives include polyvinyl alcohol resin aqueous solutions, water-based two-component urethane emulsion adhesives, and the like. Active energy ray-curable adhesives are adhesives that are cured by irradiation with active energy rays such as ultraviolet rays, such as those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, Examples include those containing a binder resin and a photoreactive crosslinking agent. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from these monomers. Examples of the photopolymerization initiator include those containing substances that generate active species such as neutral radicals, anion radicals, and cation radicals upon irradiation with active energy rays such as ultraviolet rays.

The thickness of the first adhesive layer 13 may be, for example, 1 μm or more, preferably 1 μm to 25 μm, more preferably 2 μm to 15 μm, and still more preferably 2.5 μm to 5 μm. If the thickness of the first adhesive layer 13 is 1 μm or more, stress is relaxed when the optical laminate 10 is bent, and cracks tend to be less likely to occur in the optical laminate 10.

[First retardation layer]
The first retardation layer 14 can be formed by polymerizing one or more polymerizable liquid crystals (hereinafter also referred to as polymerizable liquid crystals (b)). The first retardation layer 14 is preferably a coating layer, and may be, for example, a cured product of composition (B) described below. The first retardation layer 14 may be a positive A plate, and may be a λ/4 plate or a λ/2 plate. The first retardation layer 14 may be a positive C plate.

The first retardation layer 14 is formed by applying a composition containing one or more polymerizable liquid crystals (b) (hereinafter also referred to as composition (B)) onto a base material (hereinafter also referred to as first base material). It can be obtained by coating and polymerizing the polymerizable liquid crystal (b) in the resulting coating film. A laminate including the first retardation layer 14 and a first base material (hereinafter also referred to as a laminate 3) is a laminate including a first protective layer 11, a polarizing layer 12, and a first adhesive layer 13 (hereinafter referred to as a laminate). 1) via the first adhesive layer 13. The laminate 3 is bonded to a laminate (hereinafter also referred to as laminate 2) having a second protective layer 17, a second retardation layer 16, and a second adhesive layer 15 via a second adhesive layer 15. be able to. In either case, the bonding surface can be the first retardation layer 14. After bonding to the laminate 1 or after bonding to the laminate 2, the first base material can be peeled off. The first base material to which the composition (B) is applied can have an alignment film. As an example of the alignment film, the alignment film exemplified for the alignment film formed on the first protective layer 11 is applied.

When the optical laminate 10 is a circularly polarizing plate and the first retardation layer 14 and the second retardation layer 16 are a λ/4 plate and a positive C plate, respectively, the absorption axis of the polarizing layer 12 and the first retardation The angle between the layer 14 and the slow axis can be 45°.

When the optical laminate 10 is a circularly polarizing plate and the first retardation layer 14 and the second retardation layer 16 are a λ/4 plate and a λ/2 plate, respectively, the absorption axis of the polarizing layer 12 and the first When the angle formed by the slow axis of the retardation layer 14 is "α" and the angle formed between the absorption axis of the polarizing layer 12 and the slow axis of the second retardation layer 16 is "β", the following relational expression is obtained. Can be stacked on top of each other.

Examples of the polymerizable group that the polymerizable liquid crystal (b) has include a vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, etc. can be mentioned. Among these, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferred, and acryloyloxy group is more preferred. The liquid crystallinity of the polymerizable liquid crystal (b) may be a thermotropic liquid crystal or a lyotropic liquid crystal, and if the thermotropic liquid crystal is classified according to the degree of order, it may be a nematic liquid crystal or a smectic liquid crystal.

Among these, a thermotropic nematic liquid crystal is preferred from the viewpoint of ease of film formation, and a compound represented by the following formula (III) (hereinafter also referred to as compound (III)) is preferred. The polymerizable liquid crystals may be used alone or in combination.

［式（ＩＩＩ）中、
Ｘ^１は、酸素原子、硫黄原子またはＮＲ^１－を表わす。Ｒ^１は、水素原子または炭素数１～４のアルキル基を表わす。
Ｙ^１は、置換基を有していてもよい炭素数６～１２の１価の芳香族炭化水素基または置換基を有していてもよい炭素数３～１２の１価の芳香族複素環式基を表わす。
Ｑ^３およびＱ^４は、それぞれ独立に、水素原子、置換基を有していてもよい炭素数１～２０の１価の脂肪族炭化水素基、炭素数３～２０の１価の脂環式炭化水素基、置換基を有していてもよい炭素数６～２０の１価の芳香族炭化水素基、ハロゲン原子、シアノ基、ニトロ基、－ＮＲ^２Ｒ^３または－ＳＲ^２を表わすか、または、Ｑ^３とＱ^４とが互いに結合して、これらが結合する炭素原子とともに芳香環または芳香族複素環を形成する。Ｒ^２およびＲ^３は、それぞれ独立に、水素原子または炭素数１～６のアルキル基を表わす。
Ｄ^１およびＤ^２は、それぞれ独立に、単結合、－Ｃ（＝Ｏ）－Ｏ－、－Ｃ（＝Ｓ）－Ｏ－、－ＣＲ^４Ｒ^５－、－ＣＲ^４Ｒ^５－ＣＲ^６Ｒ^７－、－Ｏ－ＣＲ^４Ｒ^５－、－ＣＲ^４Ｒ^５－Ｏ－ＣＲ^６Ｒ^７－、－ＣＯ－Ｏ－ＣＲ^４Ｒ^５－、－Ｏ－ＣＯ－ＣＲ^４Ｒ^５－、－ＣＲ^４Ｒ^５－Ｏ－ＣＯ－ＣＲ^６Ｒ^７－、－ＣＲ^４Ｒ^５－ＣＯ－Ｏ－ＣＲ^６Ｒ^７－またはＮＲ^４－ＣＲ^５Ｒ^６－またはＣＯ－ＮＲ^４－を表わす。
Ｒ^４、Ｒ^５、Ｒ^６およびＲ^７は、それぞれ独立に、水素原子、フッ素原子または炭素数１～４のアルキル基を表わす。
Ｇ^１およびＧ^２は、それぞれ独立に、炭素数５～８の２価の脂環式炭化水素基を表わし、該脂環式炭化水素基を構成するメチレン基は、酸素原子、硫黄原子またはＮＨ－に置き換っていてもよく、該脂環式炭化水素基を構成するメチン基は、第三級窒素原子に置き換っていてもよい。
Ｌ^１およびＬ^２は、それぞれ独立に、１価の有機基を表わし、Ｌ^１およびＬ^２のうちの少なくとも一つは、重合性基を有する。］

[In formula (III),
X ¹ represents an oxygen atom, a sulfur atom or NR ¹ -. R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
Y ¹ is a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms which may have a substituent or a monovalent aromatic heterocycle having 3 to 12 carbon atoms which may have a substituent Represents a formula group.
Q ³ and Q ⁴ are each independently a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, or a monovalent alicyclic group having 3 to 20 carbon atoms; Represents a hydrocarbon group, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a substituent, a halogen atom, a cyano group, a nitro group, -NR ² R ³ or -SR ² , Alternatively, Q ³ and Q ⁴ are bonded to each other to form an aromatic ring or an aromatic heterocycle with the carbon atoms to which they are bonded. R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
D ¹ and D ² each independently represent a single bond, -C(=O)-O-, -C(=S)-O-, -CR ⁴ R ⁵ -, -CR ⁴ R ⁵ -CR ⁶ R ⁷ -, -O-CR ⁴ R ⁵ -, -CR ⁴ R ⁵ -O-CR ⁶ R ⁷ -, -CO-O-CR ⁴ R ⁵ -, -O-CO-CR ⁴ R ⁵ -, -CR ⁴ R ⁵ -O-CO-CR ⁶ R ⁷ -, -CR ⁴ R ⁵ -CO-O-CR ⁶ R ⁷ -, NR ⁴ -CR ⁵ R ⁶ - or CO-NR ⁴ -.
R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms.
G ¹ and G ² each independently represent a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and the methylene group constituting the alicyclic hydrocarbon group is an oxygen atom, a sulfur atom, or an NH - may be substituted, and the methine group constituting the alicyclic hydrocarbon group may be substituted with a tertiary nitrogen atom.
L ¹ and L ² each independently represent a monovalent organic group, and at least one of L ¹ and L ² has a polymerizable group. ]

L ¹ in compound (III) is preferably a group represented by the following formula (III-1), and L ² is preferably a group represented by formula (III-2).
P ¹ -F ¹ -(B ¹ -A ¹ ) _k -E ¹ - (III-1)
P ² -F ² -(B ² -A ² ) _l -E ² - (III-2)
[In formula (III-1) and formula (III-2),
B ¹ , B ² , E ¹ and E ² each independently represent -CR ⁴ R ⁵ -, -CH ₂ -CH ₂ -, -O-, -S-, -CO-O-, -O-CO It represents -O-, -CS-O-, -O-CS-O-, -CO-NR ¹ -, -O-CH ₂ -, -S-CH ₂ - or a single bond.
A ¹ and A ² each independently represent a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms; The methylene group constituting the group may be substituted with an oxygen atom, a sulfur atom, or NH-, and the methine group constituting the alicyclic hydrocarbon group may be substituted with a tertiary nitrogen atom. Good too.
k and l each independently represent an integer from 0 to 3.
F ¹ and F ² represent a divalent aliphatic hydrocarbon group having 1 to 12 carbon atoms.
P ¹ represents a polymerizable group.
P ² represents a hydrogen atom or a polymerizable group.
R ⁴ and R ⁵ each independently represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms. ]

Preferred compounds (III) include compounds described in JP-A No. 2011-207765.

Specific examples of the polymerizable liquid crystal (b) include "3.8.6 Network (fully crosslinked)" in the Liquid Crystal Handbook (edited by the Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2000); Among the compounds described in "6.5.1 Liquid Crystal Material b. Polymerizable Nematic Liquid Crystal Material", compounds having a polymerizable group can be mentioned.

The thickness of the first retardation layer 14 may be, for example, 0.5 μm to 5 μm, preferably 1 μm to 4 μm, and more preferably 2 μm to 3.5 μm.

[Second adhesive layer]
The optical laminate 10 has a second adhesive layer 15 between the first retardation layer 14 and the second retardation layer 16. The second adhesive layer 15 can be formed from an adhesive, an adhesive, or a combination thereof. The second adhesive layer 15 is usually one layer, but may be two or more layers. The second adhesive layer 15 may be formed in contact with the first retardation layer 14 or the second retardation layer 16.

As the pressure-sensitive adhesive and adhesive used for the second adhesive layer 15, the pressure-sensitive adhesives and adhesives exemplified in the description of the first adhesive layer 14 above can be used.

The thickness of the second adhesive layer 15 may be, for example, 1 μm or more, preferably 1 μm to 25 μm, more preferably 2 μm to 15 μm, and even more preferably 2.5 μm to 5 μm. If the thickness of the second adhesive layer 15 is 3 μm or more, stress is relaxed when the optical laminate 10 is bent, and cracks tend to be less likely to occur in the optical laminate 10.

[Second retardation layer]
The second retardation layer 16 can be formed by polymerizing one or more polymerizable liquid crystals (hereinafter also referred to as polymerizable liquid crystals (c)). The second retardation layer 16 is preferably a coating layer, and may be, for example, a cured product of composition (C) described below. The second retardation layer 16 may be a positive A plate or a λ/4 plate. The second retardation layer 16 may be a positive C plate.

The second retardation layer 16 is formed by applying, for example, a composition containing one or more polymerizable liquid crystals (c) (hereinafter also referred to as composition (C)) onto the second protective layer 17. It can be formed by polymerizing the polymerizable liquid crystal (c) in the film. The second protective layer 17 may include an alignment film.

When the optical laminate 10 is a circularly polarizing plate, the angle between the absorption axis of the polarizing layer 12 and the slow axis of the first retardation layer 14 is "α", and the angle between the absorption axis of the polarizing layer 12 and the second retardation layer 16 is "α". When the angle formed with the slow axis is "β", the layers can be stacked so that the following relational expression is satisfied.

As the polymerizable liquid crystal (c), those exemplified in the explanation of the polymerizable liquid crystal (b) above can be used.

The thickness of the second retardation layer 16 may be, for example, 0.5 μm to 5 μm, preferably 1 μm to 4 μm, and more preferably 2 μm to 3.5 μm.

[Second protective layer]
From the viewpoint of bendability of the optical laminate 10, the second protective layer 17 may be made of, for example, a resin film, preferably a transparent resin film. The resin film may be a long roll-shaped resin film or a sheet-shaped resin film. A long roll-shaped resin film is preferred since it can be manufactured continuously. As the resin constituting the resin film, the resins, resin films, and commercially available resin films exemplified in the description of the first protective layer 11 can be used. The second protective layer 17 can be a layer that is incorporated into the display device without being peeled off.

The thickness of the resin film is preferably thinner from the viewpoint of making the optical laminate 10 thinner, but if it is too thin, it tends to be difficult to ensure impact resistance. The thickness of the resin film may be, for example, 5 to 100 μm, preferably 10 to 80 μm, and more preferably 15 to 60 μm. The thickness of the first protective layer and the thickness of the second protective layer may be the same or different. The first protective layer may be thicker than the second protective layer.

The ratio (A/B) of the thickness (A) of the first protective layer to the thickness (B) of the second protective layer is 3.3 or less, preferably 0.5 to 3.3, more preferably 0. 5 to 3.0, more preferably 1 to 3.0. When the optical laminate satisfies such a ratio, cracks are less likely to occur in the optical laminate when bent.

The second protective layer may have a modified toughness defined by the following formula (1) of, for example, 2300 MPa·% or more, preferably 2400 MPa·% or more, more preferably 2500 MPa·% or more, and even more preferably 2600 MPa·%. % or more, particularly preferably 2700 MPa·% or more. On the other hand, the modified toughness is, for example, 10,000 MPa·% or less. When the second protective layer satisfies such modified toughness, cracks are less likely to occur in the optical laminate during bending.
Modified toughness = maximum stress x maximum strain (1)
[However, maximum stress and maximum strain indicate the stress and strain at the point of failure in the stress-strain curve, respectively.]

The modified toughness can be measured according to the method for measuring modified toughness in Examples described below.

The second protective layer 17 may include an alignment film. As an example of the alignment film, the alignment film exemplified for the alignment film formed on the first protective layer 11 can be applied.

One or both surfaces of the second protective layer 17 may be subjected to hard coat treatment, antireflection treatment, antistatic treatment, or the like.

<Method for manufacturing optical laminate>
The first embodiment of the method for manufacturing the optical laminate 10 includes the following steps.
1) A step of preparing a laminate A31 having a first protective layer 11 and a polarizing layer 12, and a first adhesive sheet 34 having a release film A18, a first adhesive layer 13, and a release film B19 (FIG. 2a).
2) A step of peeling off the release film A18 of the first adhesive sheet 34 and bonding the first adhesive layer 13 of the first adhesive sheet 34 and the polarizing layer 12 of the laminate A31. A step of preparing a laminate C33 having the first retardation layer 14 and the first base material (release film C) 20 (FIG. 2b).
3) A step of peeling off the release film B19 of the laminate A31 and bonding the first adhesive layer 13 of the laminate A31 and the first retardation layer 14 of the laminate C33. A step of preparing a second adhesive sheet 35 having a release film D21, a second adhesive layer 15, and a release film E22 (FIG. 2c).
4) Peel off the first base material (release film C) 20, peel off the release film D21 of the second adhesive sheet 35, and remove the first retardation layer 14 and the second adhesive layer 15 of the second adhesive sheet 35. The process of pasting. A step of preparing a laminate B32 having the second protective layer 17 and the second retardation layer 16 (FIG. 2d).
5) A step of peeling off the release film E22 and bonding the second adhesive layer 15 and the second retardation layer 16 of the laminate B32 (FIG. 2e).
Each step can be performed continuously.

In step 4) of preparing the laminate B32, when laminating the second protective layer 17 and the second retardation layer 16, the surface of the second protective layer 17 on the side on which the second retardation layer 16 is laminated is Corona treatment may also be performed. The corona treatment can be performed once or multiple times under conditions of, for example, an output of 0.1 to 1.0 kW and a processing speed of 0.1 to 20 m/min.

The second embodiment of the method for manufacturing the optical laminate 10 includes the following steps.
1) Step of preparing a second adhesive sheet 35 having a release film D21, a second adhesive layer 15 and a release film E22, and a laminate B32 having a second protective layer 17 and a second retardation layer 16 (FIG. 3a) .
2) A step of preparing a laminate C33 having the first retardation layer 14 and the first base material (release film C) 20. A step of peeling off the release film D21 and bonding the second adhesive layer 15 and the second retardation layer 16 of the laminate B32 (FIG. 3b).
3) A step of preparing a first adhesive sheet 34 having a release film A18, a first adhesive layer 13, and a release film B19. A step of peeling off the release film E22, bonding the first retardation layer 14 and the second adhesive layer 15, and peeling off the first base material (release film C) 20 of the laminate C33 (FIG. 3c).
4) A step of preparing a laminate A31 having the first protective layer 11 and the polarizing layer 12. A step of peeling off the release film A18 of the first adhesive sheet 34 and bonding the first adhesive layer 13 and the first retardation layer 14 (FIG. 3d).
5) A step of peeling off the release film B19 and bonding the first adhesive layer 13 and the polarizing layer 12 of the laminate A31 (FIG. 3e).

(Laminated body A)
The polarizing layer 12 of the laminate A31 includes one or more polymerizable liquid crystals (a) and a dichroic dye on the first protective layer 11, or on the alignment film when the first protective layer 11 has an alignment film. It can be manufactured by applying a composition (A) containing the following and polymerizing the polymerizable liquid crystal (a). The composition (A) further contains a solvent, a polymerization initiator, and may further contain a sensitizer, a polymerization inhibitor, a leveling agent, a reactive additive, and the like.

When the composition (A) contains a solvent, the composition (A) is made by dissolving a polymerizable liquid crystal compound, which generally has a high viscosity, in a solvent, making it easier to apply and, as a result, easier to form a polarizing film. There is a tendency. The solvent is preferably one that can completely dissolve the polymerizable liquid crystal compound, and is also preferably a solvent that is inert to the polymerization reaction of the polymerizable liquid crystal compound.

Examples of solvents include alcoholic solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, and γ-butyrolactone. or ester solvents such as propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; toluene and aromatic hydrocarbon solvents such as xylene, nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, Examples include amide solvents such as 1,3-dimethyl-2-imidazolidinone. These solvents may be used alone or in combination of two or more.

The content of the solvent is preferably 50 to 98% by mass based on the total amount of composition (A). In other words, the solid content in composition (A) is preferably 2 to 50% by mass. When the solid content is 50% by mass or less, the viscosity of the composition (A) becomes low, so that the thickness of the polarizing layer 12 becomes approximately uniform, causing unevenness in the polarizing layer 12. It tends to get harder. Further, the solid content can be determined in consideration of the thickness of the polarizing layer 12 to be manufactured.

Composition (A) may contain a polymerization initiator. A polymerization initiator is a compound that can initiate a polymerization reaction of polymerizable liquid crystals and the like. As the polymerization initiator, a photopolymerization initiator that generates active radicals by the action of light is preferred from the viewpoint of not depending on the phase state of the thermotropic liquid crystal.

Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, and sulfonium salts.
The number of polymerization initiators in the composition (A) may be one, or two or more types of polymerization initiators may be mixed depending on the light source.

The content of the polymerization initiator in the composition (A) can be adjusted as appropriate depending on the type and amount of the polymerizable liquid crystal, but is usually 0.1 to 30 parts by mass per 100 parts by mass of the polymerizable liquid crystal. Parts by weight, preferably 0.5 to 10 parts by weight, more preferably 0.5 to 8 parts by weight. When the content of the polymerization initiator is within the above range, polymerization can be carried out without disturbing the orientation of the polymerizable liquid crystal.

Composition (A) may contain a sensitizer. As the sensitizer, a photosensitizer is preferred. Examples of the sensitizer include xanthone compounds such as xanthone and thioxanthone (for example, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene such as anthracene and anthracene containing an alkoxy group (for example, dibutoxyanthracene, etc.); Compounds include phenothiazine and rubrene.

When the composition (A) contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal contained in the composition (A) can be further promoted. The amount of the sensitizer used is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, and 0.5 to 3 parts by weight based on 100 parts by weight of the polymerizable liquid crystal. is even more preferable.

From the viewpoint of stably proceeding the polymerization reaction, the composition (A) may contain a polymerization inhibitor. The degree of progress of the polymerization reaction of the polymerizable liquid crystal can be controlled by the polymerization inhibitor.

Examples of polymerization inhibitors include radical scavengers such as hydroquinone, alkoxy group-containing hydroquinone, alkoxy group-containing catechol (such as butylcatechol), pyrogallol, and 2,2,6,6-tetramethyl-1-piperidinyloxy radical. agents; thiophenols; β-naphthylamines, β-naphthols, etc.

When the composition (A) contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 to 10 parts by mass, more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal. The amount is 5 to 5 parts by weight, more preferably 0.5 to 3 parts by weight. When the content of the polymerization inhibitor is within the above range, polymerization can be performed without disturbing the orientation of the polymerizable liquid crystal.

Composition (A) may contain a leveling agent. A leveling agent is an additive that has the function of adjusting the fluidity of the composition and making the film obtained by applying the composition more flat, and examples include organically modified silicone oil, polyacrylate, and perfluorinated silicone oil. Examples include alkyl leveling agents.

When the composition (A) contains a leveling agent, it is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, even more preferably It is 0.1 to 3 parts by mass. When the content of the leveling agent is within the above range, it is easy to horizontally align the polymerizable liquid crystal, and the resulting polarizing film tends to be smoother. When the content of the leveling agent in the polymerizable liquid crystal exceeds the above range, the resulting polarizing film tends to be uneven. In addition, the composition (A) may contain two or more types of leveling agents.

Composition (A) may also contain reactive additives. The reactive additive preferably has a carbon-carbon unsaturated bond and an active hydrogen-reactive group in its molecule. The term "active hydrogen-reactive group" as used herein refers to a group that is reactive with groups having active hydrogen, such as carboxyl group (-COOH), hydroxyl group (-OH), and amino group (-NH ₂ ). Representative examples thereof include a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an isocyanate group, a thioisocyanate group, and a maleic anhydride group. The number of carbon-carbon unsaturated bonds and active hydrogen-reactive groups that the reactive additive has is usually 1 to 20 each, preferably 1 to 10 each.

In the reactive additive, it is preferable that at least two active hydrogen-reactive groups exist, and in this case, the plurality of active hydrogen-reactive groups may be the same or different.

The carbon-carbon unsaturated bond possessed by the reactive additive may be a carbon-carbon double bond, a carbon-carbon triple bond, or a combination thereof, and is preferably a carbon-carbon double bond. Among these, the reactive additive preferably contains a carbon-carbon unsaturated bond as a vinyl group and/or (meth)acrylic group. Furthermore, a reactive additive whose active hydrogen-reactive group is at least one selected from the group consisting of an epoxy group, a glycidyl group, and an isocyanate group is preferable, and a reactive additive having an acrylic group and an isocyanate group is more preferable. .

Specific examples of reactive additives include compounds having a (meth)acrylic group and an epoxy group, such as methacryloxyglycidyl ether and acryloxyglycidyl ether; Compounds having a (meth)acrylic group and a lactone group, such as lactone acrylate and lactone methacrylate; Compounds having a vinyl group and an oxazoline group, such as vinyloxazoline and isopropenyloxazoline; Isocyanatomethyl acrylate Examples include oligomers of compounds having a (meth)acrylic group and an isocyanate group, such as isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate. Other examples include compounds having a vinyl group or vinylene group and an acid anhydride, such as methacrylic anhydride, acrylic anhydride, maleic anhydride, and vinyl maleic anhydride. Among them, methacryloxyglycidyl ether, acryloxyglycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyloxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate and the above-mentioned oligomers are preferred, and isocyanatomethyl acrylate, Particular preference is given to 2-isocyanatoethyl acrylate and the oligomers mentioned above.

Specifically, a compound represented by the following formula (Y) is preferred.

[In formula (Y),
n represents an integer from 1 to 10, and R ^1' is a divalent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 5 to 20 carbon atoms. represents. One of the two R ^2's in each repeating unit is -NH-, and the other is a group represented by >N-C(=O)-R ^3' . R ^3' represents a hydroxyl group or a group having a carbon-carbon unsaturated bond.
At least one R ^{3 '} in the formula (Y) is a group having a carbon-carbon unsaturated bond. ]

Among the reactive additives represented by the formula (Y), the compound represented by the following formula (YY) (hereinafter sometimes referred to as compound (YY)) is particularly preferable (n is the same as above). meaning).

As the compound (YY), a commercially available product can be used as it is or purified if necessary. Examples of commercially available products include Laromer (registered trademark) LR-9000 (manufactured by BASF).

When the composition (A) contains a reactive additive, the content of the reactive additive is usually 0.01 to 10 parts by mass, preferably 0.1 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal. ~5 parts by mass.

Methods for applying the composition (A) onto the first protective layer 11 or the alignment film include extrusion coating, direct gravure coating, reverse gravure coating, CAP coating, slit coating, microgravure, and die coating. method, inkjet method, etc. Other examples include a method of coating using a coater such as a dip coater, a bar coater, or a spin coater. Among them, when applying continuously in a roll-to-roll format, a coating method using a microgravure method, an inkjet method, a slit coating method, or a die coating method is preferable, and when the first protective layer 11 is sheet-shaped, A spin coating method with high uniformity is preferred. When coating in a Roll to Roll format, a composition for forming an alignment film (hereinafter also referred to as an alignment polymer composition) or the like is coated on the first protective layer 11 to form an alignment film, and the obtained The composition (A) can also be continuously applied onto the alignment film.

Examples of the drying method for removing the solvent contained in the composition (A) include natural drying, ventilation drying, heat drying, reduced pressure drying, and combinations thereof. Among these, natural drying or heat drying is preferred. The drying temperature is preferably in the range of 0 to 200°C, more preferably in the range of 20 to 150°C, even more preferably in the range of 50 to 130°C. The drying time is preferably 10 seconds to 10 minutes, more preferably 30 seconds to 5 minutes. Oriented polymer compositions can be similarly dried.

(Polymerization of polymerizable liquid crystal)
As a method for polymerizing the polymerizable liquid crystal (a), photopolymerization is preferred. Photopolymerization is carried out by irradiating active energy rays to the laminate in which the composition (A) and the polymerizable liquid crystal (a) are applied on the first protective layer or alignment film. The active energy rays to be irradiated include the type of polymerizable liquid crystal (A) contained in the dry film (in particular, the type of photopolymerizable functional group possessed by the polymerizable liquid crystal (A)), and when it contains a photopolymerization initiator. It is appropriately selected depending on the type and amount of the photopolymerization initiator. Specifically, one or more types of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays can be mentioned. Among these, ultraviolet light is preferable because it is easy to control the progress of the polymerization reaction and it is possible to use photopolymerization equipment that is widely used in the field. It is preferable to select the type of liquid crystal (a).

Examples of the light source of the active energy ray include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, and a wavelength range. Examples include an LED light source that emits light in the range of 380 to 440 nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

The ultraviolet irradiation intensity is usually 10 mW/cm ² to 3,000 mW/cm ² . The ultraviolet irradiation intensity is preferably in a wavelength range effective for activating a cationic polymerization initiator or a radical polymerization initiator. The time for irradiating the light is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds. ~1 minute. When irradiated once or multiple times with such ultraviolet irradiation intensity, the cumulative amount of light is 10 mJ/cm ² to 3,000 mJ/cm ² , preferably 50 mJ/cm ² to 2,000 mJ/cm ² , more preferably 100 mJ /cm ² to 1,000 mJ/cm ² . When the cumulative amount of light is within this range, the polymerizable liquid crystal (A) is sufficiently cured, good transferability is easily obtained, and coloring of the optical laminate tends to be easily suppressed.

(Laminated body B)
The second retardation layer 16 of the laminate B32 contains one or more polymerizable liquid crystals (c) on the second protective layer 17, or on the alignment film if the second protective layer 17 has an alignment film. It can be manufactured by applying a second retardation layer forming composition (C) (hereinafter also referred to as composition (C)) and polymerizing the polymerizable liquid crystal (c). Composition (C) further contains a solvent, a polymerization initiator, and may further contain a photosensitizer, a polymerization inhibitor, a leveling agent, and the like.

The coating and drying of the composition (C) and the polymerization of the polymerizable liquid crystal (c) are the same as those of the coating and drying of the composition (A) and the polymerization of the polymerizable liquid crystal (a) exemplified in the step of forming laminate A31 described above. can be done.

(Laminated body C)
The first retardation layer 14 of the laminate C33 includes a first retardation layer containing one or more polymerizable liquid crystals (b) on the first base material, or on the alignment film when the first base material has an alignment film. 1. It can be manufactured by applying a retardation layer forming composition (B) (hereinafter also referred to as composition (B)) and polymerizing the polymerizable liquid crystal (b). Composition (B) further contains a solvent, a polymerization initiator, and may further contain a photosensitizer, a polymerization inhibitor, a leveling agent, and the like.

The coating and drying of the composition (B) and the polymerization of the polymerizable liquid crystal (b) are the same as the coating and drying of the composition (A) and the polymerization of the polymerizable liquid crystal (a) exemplified in the step of forming laminate A31 described above. can be done.

(First adhesive sheet and second adhesive sheet)

The first adhesive sheet 34 and the second adhesive sheet 35 are prepared by dissolving or dispersing an adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare an adhesive solution, and then releasing the adhesive composition by dissolving or dispersing it in an organic solvent such as toluene or ethyl acetate. It can be produced by forming a layer made of an adhesive in the form of a sheet on film B19 or release film E22, and then laminating another release film A18 or release film D21 on the adhesive layer. .

The third embodiment of the method for manufacturing the optical laminate 10 includes the following steps.
1) A laminate C33 having a first retardation layer 14 and a first base material (release film C) 20 is prepared, and an adhesive is applied to the surface of the laminate 33C on the first retardation layer 14 side. Step 2 of forming the adhesive layer 15. Step of preparing a laminate B32 having the second protective layer 17 and the second retardation layer 16 (FIG. 4a).
2) A step of laminating the second adhesive layer 15 and the second retardation layer 16 of the laminate B32 (FIG. 4b).
3) A step of preparing a first adhesive sheet 34 having a release film A 18, a first adhesive layer 13, and a release film B 19, and peeling off the first base material (release film C) 20 (FIG. 4c).
4) A step of preparing a laminate A31 having the first protective layer 11 and the polarizing layer 12. A step of peeling off the release film A18 of the first adhesive sheet 34 and bonding the first adhesive layer 13 and the first retardation layer 14 (FIG. 4d).
5) A step of peeling off the release film B19 and bonding the first adhesive layer 13 to the first retardation layer 14 of the laminate A31 (FIG. 4d).

The fourth embodiment of the method for manufacturing the optical laminate 10 includes the following steps.
1) A step of preparing a laminate A31 having the first protective layer 11 and the polarizing layer 12. A laminate C33 having a first retardation layer 14 and a first base material (release film C) 20 is prepared, and an adhesive is applied to the surface of the laminate 33C on the first retardation layer 14 side to form a first adhesive layer. 13 (FIG. 5a).
2) A step of laminating the first adhesive layer 13 and the polarizing layer 12 of the laminate A31 (FIG. 5b).
3) A step of preparing a second adhesive sheet 35 having a release film D21, a second adhesive layer 15, and a release film E22 (FIG. 5c).
4) A step of peeling off the first base material (release film C) 20, peeling off the release film D21, and bonding the first retardation layer 14 and the second adhesive layer 15. Step of preparing a laminate B32 having the second protective layer 17 and the second retardation layer 16 (FIG. 5d).
5) A step of peeling off the release film E22 and bonding the second adhesive layer 15 and the second retardation layer 16 (FIG. 5e).

The fifth embodiment of the method for manufacturing the optical laminate 10 includes the following steps.
1) Prepare a laminate C33 having a first retardation layer 14 and a first base material (release film C) 20, prepare a laminate B32 having a second protective layer 17 and a second retardation layer 16, and bond (FIG. 6a) preparing a second adhesive layer 15 consisting of an adhesive.
2) A step of bonding the laminate C33 and the laminate B32 via the second adhesive layer 15 (FIG. 6b).
3) Step of peeling off the first base material (release film C) 20 (FIG. 6c).
4) A step of preparing a laminate A31 having a first protective layer 11 and a polarizing layer 12, and applying an adhesive to the surface of the laminate A31 on the polarizing layer 12 side to form a first adhesive layer 13 (FIG. 6d) .
5) A step of laminating the first adhesive layer 13 and the first retardation layer 14 (FIG. 6e).

When the first adhesive layer 13 is made of an adhesive, the first adhesive layer 13 is formed by coating the adhesive on the surface of the polarizing layer 12 side or the surface of the first retardation layer 14 side. or the surface of the polarizing layer 12 can be bonded together and cured.

When the second adhesive layer 15 is made of an adhesive, the second adhesive layer 15 is applied to the surface of the first retardation layer 14 side or the surface of the second retardation layer 16, and The surface or the surface of the first retardation layer 14 can be bonded together and cured.

The method of applying the adhesive is not particularly limited as long as it can be applied to the surfaces of the polarizing layer 12, first retardation layer 14, and second retardation layer 16, but for example, a doctor blade, wire bar, die coater, comma coater, etc. , gravure coater, etc. The coating thickness (thickness of the curable composition layer before curing) is preferably about 1 to 20 μm, more preferably 2 to 15 μm.

When the adhesive is an active energy ray-curable adhesive, the light source used for irradiation with active energy rays is not particularly limited, but is preferably a light source having a light emission distribution at a wavelength of 400 nm or less. Examples of such light sources include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. It is preferable that the irradiation with active energy rays be carried out in multiple doses.

The intensity of light irradiation to the active energy ray-curable composition each time is determined depending on the composition of the composition and is not particularly limited, but is preferably 10 to 5000 mW/cm ² . If the light irradiation intensity to the active energy ray curable composition is less than 10 mW/cm ² , the reaction time will be too long, and if it exceeds 5000 mW/cm ² , the heat radiated from the light source and the active energy ray curable composition will be too long. The heat generated during polymerization of the material may cause yellowing of the curable resin, which is a constituent material of the active energy ray-curable composition, and deterioration of the first protective layer 11 and the second protective layer 17. The irradiation intensity is preferably an intensity in a wavelength range effective for activating the polymerization initiator, more preferably an intensity in a wavelength range of 400 nm or less, and even more preferably an intensity in a wavelength range of 280 to 320 nm. It is.

When the active energy rays 15 are ultraviolet rays, the irradiation section applies a tension of 100 to 800 N/m in the longitudinal direction (transportation direction) toward the laminate 13, and applies a tension such that the irradiation time is 0.1 seconds or more. It is preferable to convey the laminate 13 at line speed. The total time for irradiating active energy is not particularly limited as long as it is a time that can cure the active energy ray-curable composition in the curable composition layer 14, but for example, the total time for irradiating the active energy may be 30 mJ/cm2 ^or more. Bye.

When using a water-based adhesive as the adhesive, the adhesive is applied to the surface on the polarizing layer 12 side or the surface on the first retardation layer 14 side of the laminate 3, and the first retardation layer 14 of the laminate 3 is coated. After bonding the surface of the polarizing layer 12 or the surface of the polarizing layer 12 of the laminate 1, it is preferable to perform a drying step to remove water contained in the water-based adhesive. After the drying step, a curing step of curing at a temperature of, for example, 20 to 45° C. may be provided.

<Display device>
In a display device according to an embodiment of the present invention, an optical laminate 10 is bonded to an image display element via an adhesive layer. The optical laminate 10 can be bonded to the image display element such that the first protective layer 11 is disposed on the viewing side with respect to the second protective layer 17. The adhesive layer can be provided on any surface of the optical laminate 10 depending on the use of the optical laminate 10. The adhesive is not particularly limited, and the adhesives described below can be used. An adhesive can be formed on the second protective layer.

The display device is not particularly limited, and includes, for example, an organic electroluminescent (organic EL) display device, an inorganic electroluminescent (inorganic EL) display device, a liquid crystal display device, a touch panel display device, an electroluminescent display device, and the like. The optical laminate 10 can be suitably used in a foldable display device.

Hereinafter, the present invention will be explained in more detail with reference to Examples. "%" and "parts" in the examples are mass % and parts by mass unless otherwise specified.

[Measurement of thickness]
The thickness of each layer forming the optical laminate was measured using a contact film thickness measuring device (MS-5C manufactured by Nikon Corporation).

[Flexibility test]
Flexibility tests were conducted on the optical laminates obtained in each Example and Comparative Example as follows. FIG. 7 is a diagram schematically showing the method of this evaluation test. A bending device (STS-VRT-500, manufactured by Science Town) equipped with two stages 501 and 502 was prepared, and the optical laminate 100 was placed on the stages 501 and 502 (FIG. 7a). The distance (gap) C between the two stages 501 and 502 was set to 5 mm (2.5R) or 2 mm (1.0R). The stages 501 and 502 are swingable around a gap C between the two stages, and initially the two stages 501 and 502 form the same plane. The two stages 501, 502 are rotated 90 degrees upwards about positions P1 and P2 as the center of the rotation axis to close the two stages 501, 502 (FIG. 7b), and the operation of opening the stages 501, 502 again is performed once. Defined as bending. This operation was repeated and the number of times the optical laminate 100 was bent until the first crack appeared was counted. The evaluation criteria are as follows.
◎ (very good): 200,000 times or more, ○ (good): 100,000 times or more and less than 200,000 times, △ (usable): 50,000 times or more and less than 100,000 times, × (slightly poor): 10,000 times or more Less than 50,000 times, ×× (poor): Less than 10,000 times

[Measurement of modified toughness]
Using the second protective layer of the optical laminate in each Example and Comparative Example as a sample, stress-strain was measured using a UTM (Universal Testing Machine (Autograph AG-X manufactured by Shimadzu Corporation) in accordance with JIS K7161. A curve was created. The maximum stress and maximum strain were each determined from the fracture point in the stress-strain curve. The modified toughness was determined according to the following equation (1).
Modified toughness = maximum stress x maximum strain (1)

[Polymerizable liquid crystal compound]
The polymerizable liquid crystal compound includes a polymerizable liquid crystal compound represented by formula (1-6) [hereinafter also referred to as compound (1-6)] and a polymerizable liquid crystal compound represented by formula (1-7) [hereinafter referred to as compound (1-6)]. Also referred to as compound (1-7)] was used.

Compound (1-6) and compound (1-7) were prepared by Lub et al. Recl. Trav. Chim. It was synthesized by the method described in Pays-Bas, 115, 321-328 (1996).

As the dichroic dye, azo dyes described in Examples of JP-A No. 2013-101328, which are represented by the following formulas (2-1a), (2-1b), and (2-3a), were used.

[Polarizer layer forming composition]
The composition for forming a polarizer layer [hereinafter also referred to as composition (A-1)] contains 75 parts by weight of compound (1-6), 25 parts by weight of compound (1-7), and the above formula as a dichroic dye. 2.5 parts by weight each of the azo dyes represented by (2-1a), (2-1b), and (2-3a), 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl) as a polymerization initiator; ) 6 parts by weight of butan-1-one (Irgacure 369, manufactured by BASF Japan) and 1.2 parts by weight of a polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) as a leveling agent, and 400 parts by weight of toluene as a solvent. and stirred the resulting mixture at 80° C. for 1 hour.

[First retardation layer forming composition]
Composition (B-1) was obtained by mixing the components shown below and stirring the resulting mixture at 80° C. for 1 hour.
Compound b-1 represented by the following formula: 80 parts by weight

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

Polymerization initiator (Irgacure 369, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one, manufactured by BASF Japan): 6 parts by weight Leveling agent (BYK-361N, polyacrylate compound, BYK -Chemie): 0.1 parts by weight Solvent (cyclopentanone): 400 parts by weight

[Composition for forming second retardation layer]
Composition (C-1) was obtained by mixing the components shown below and stirring the resulting mixture at 80° C. for 1 hour.
Compound c-1 represented by the following formula (LC242, manufactured by BASF Japan): 100 parts by weight

Polymerization initiator (Irgacure 907, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, manufactured by BASF Japan): 2.6 parts by weight Leveling agent (BYK-361N, polyacrylate compound, BYK-Chemie) ): 0.5 parts by weight Additive (LR9000, manufactured by BASF Japan): 5.7 parts by weight Solvent (propylene glycol 1-monomethyl ether 2-acetate): 412 parts by weight

[Polymer 1]
Polymer 1 having a photoreactive group consisting of the following structural units was prepared.

[Composition for forming alignment film]
A solution of Polymer 1 dissolved in cyclopentanone at a concentration of 5% by weight was used as a composition for forming an alignment film [hereinafter also referred to as composition (D-1)].

[Laminated body A]
Formation of First Protective Layer A cellulose film (TAC film, manufactured by Konica Minolta, Inc., thickness 25 μm, TAC1) was used as the first protective layer. The composition (D-1) obtained as described above was applied onto the film by a bar coating method and dried by heating in a drying oven at 80° C. for 1 minute. The obtained dried film was subjected to polarized UV irradiation treatment to form a first alignment film (AL1). Polarized UV treatment is performed by transmitting light emitted from a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) through a wire grid (UIS-27132##, manufactured by Ushio Inc.) at a wavelength of 365 nm. The measurement was carried out under the condition that the cumulative light amount measured in 1 was 100 mJ/cm ² . The thickness of the first alignment film (AL1) was 100 nm.

Formation of Polarizing Layer Composition (A-1) was applied on the formed first alignment film (AL1) by a bar coating method, heated and dried in a drying oven at 120° C. for 1 minute, and then cooled to room temperature. A polarizing layer (pol) was formed by irradiating the dry film with ultraviolet rays at a cumulative light intensity of 1200 mJ/cm ² (based on 365 nm) using the above UV irradiation device. The thickness of the obtained polarizing layer (pol) was measured using a laser microscope (OLS3000 manufactured by Olympus Corporation) and was found to be 1.8 μm. In this way, a laminate A consisting of polarizing layer (pol)/first alignment film (AL1)/first protective layer (TAC1) was obtained.

[Laminated body B]
Formation of second protective layer TAC1 was used as the second protective layer. A single corona treatment was performed on the film. The conditions for the corona treatment were an output of 0.3 kW and a treatment speed of 3 m/min. Composition (D-1) was applied onto the film by a bar coating method and dried by heating in a drying oven at 90° C. for 1 minute to obtain a second alignment film (AL2).

Formation of Second Retardation Layer Composition (C-1) was applied onto the second alignment film (AL2) of the second protective layer by a bar coating method and dried by heating in a drying oven at 90° C. for 1 minute. A retardation layer was formed on the obtained dried film by irradiating ultraviolet rays with an integrated light amount of 1000 mJ/cm ² (365 nm standard) using the above-mentioned UV irradiation device in a nitrogen atmosphere. The thickness of the obtained retardation layer was measured using a laser microscope (OLS3000 manufactured by Olympus Corporation) and was found to be 2.0 μm. The second retardation layer was a positive C plate (posiC) showing a retardation in the thickness direction. In this way, a laminate B consisting of the second retardation layer (posiC)/second alignment film (AL2)/second protective layer (TAC2) was obtained.

[Laminated body C]
Formation of the first retardation layer A polyethylene terephthalate film (PET) with a thickness of 100 μm was prepared as the first base material, and the composition (D-1) was applied onto the film by a bar coating method, and the film was placed in a drying oven at 80°C. It was heated and dried for 1 minute. The obtained dried film was subjected to polarized UV irradiation treatment to form a third alignment film (AL3). The polarized UV treatment was performed using the UV irradiation device described above under the condition that the cumulative amount of light measured at a wavelength of 365 nm was 100 mJ/cm ² . Further, the polarization direction of the polarized UV light was set at 45° with respect to the absorption axis of the polarizing layer.

Composition (B-1) was applied onto the third alignment film (AL3) of the first base material obtained in this manner by a bar coating method, heated and dried in a drying oven at 120°C for 1 minute, and then cooled to room temperature. did. The obtained dried film was irradiated with ultraviolet rays at a cumulative light amount of 1000 mJ/cm ² (based on 365 nm) using the UV irradiation device described above to form a first retardation layer. The thickness of the obtained first retardation layer was measured using a laser microscope (OLS3000 manufactured by Olympus Corporation) and was found to be 2.0 μm. The first retardation layer was a λ/4 plate (QWP) exhibiting a retardation value of λ/4 in the in-plane direction. In this way, a laminate C consisting of the first retardation layer (QWP)/third alignment film (AL3)/first base material (PET) was obtained.

[Adhesive sheet]
Adhesive sheets for forming the first adhesive layer and the second adhesive layer (adhesive sheets for forming the first and second adhesive layers) were produced as follows.
An acrylic resin was obtained by mixing and reacting the following components at 55° C. under a nitrogen atmosphere.
Butyl acrylate: 70 parts Methyl acrylate: 20 parts Acrylic acid: 1.0 part Initiator (azobisisobutylnitrile): 0.2 parts Solvent (ethyl acetate): 80 parts Coronate L ( Tosoh Corporation), 0.5 part of silane coupling agent As a result, a composition for forming an adhesive was obtained. The resulting adhesive-forming composition was applied to the release-treated surface of a polyethylene terephthalate film (SpB, thickness 38 μm) using an applicator so that the thickness after drying was 5 μm. The coating film was dried at 100° C. for 1 minute to obtain a film provided with an adhesive (PSA1 or PSA2). Thereafter, another release-treated polyethylene terephthalate film (SpA, thickness 38 μm) was laminated onto the exposed adhesive surface. Thereafter, it was cured for 7 days at 23° C. and 50% RH. In this way, a pressure-sensitive adhesive sheet consisting of release film A (SpA)/adhesive (PSA1 or PSA2)/release film B (SpB) was produced.

<Example 1>
A laminate A (pol/AL1/TAC1) and a pressure-sensitive adhesive sheet for forming a first adhesive layer (SpA/PSA1/SpB) were prepared.
Release film A was peeled off from the adhesive sheet for forming the first adhesive layer (PSA1/SpB). A laminate A1 (SpB/PSA1/pol/AL1/TAC1) was obtained by laminating the surface of the laminate A on the polarizing layer side and the peeled surface of the adhesive sheet for forming the first adhesive layer.
Release film B is peeled off from laminate A1 (PSA1/pol/AL1/TAC1), and the first adhesive layer surface and the surface of laminate C on the first retardation layer side are bonded together to form laminate A2 (PET/AL3). /QWP/PSA1/pol/AL1/TAC1) was obtained.
PET is peeled off from the laminate A2 (AL3/QWP/PSA1/pol/AL1/TAC1), release film A is peeled off from the adhesive sheet for forming the second adhesive layer (PSA2/SpB), and the second adhesive layer surface and the laminate are separated. The third alignment film side surface of A2 was bonded to obtain a laminate A3 (Spb/PSA2/AL3/QWP/PSA1/pol/AL1/TAC1).
Release film B is peeled off from laminate A3, and the second adhesive layer surface of laminate A3 and the surface of laminate B on the second retardation layer side are bonded to form an optical laminate (TAC1/AL2/posiC/PSA2/ AL3/QWP/PSA1/pol/AL1/TAC1) was obtained.
Table 1 shows the thickness of each layer, the modified toughness of the second protective layer, and the bending test results for the obtained optical laminate.

<Example 2>
Example 1 except that the thickness of the first protective layer was changed to the thickness (TAC3) shown in Table 1, and the type and thickness of the second protective layer were changed to the type and thickness (PET) shown in Table 1. An optical laminate was obtained in the same manner as above. The results are shown in Table 1. In Table 1, PET means polyethylene terephthalate film.

<Example 3>
An optical laminate was obtained in the same manner as in Example 1, except that the type and thickness of the first protective layer were changed to those shown in Table 1 (HC-PI). The results are shown in Table 1. In Table 1, HC-PI means a polyimide film having a hard coat layer on the surface.

<Example 4>
Laminate A (pol/AL1/HC-PI) in which the type and thickness of the first protective layer were changed to those shown in Table 1 (HC-PI) and the adhesive sheet for forming the first adhesive layer (SpA/PSA1/ SpB) was prepared.
Release film A was peeled off from the adhesive sheet for forming the first adhesive layer (PSA1/SpB). A laminate A1 (SpB/PSA1/pol/AL1/HC-PI) was obtained by pasting together the polarizing layer side surface of the laminate A and the peeled surface of the adhesive sheet for forming the first adhesive layer.
Release film B is peeled off from laminate A1 (PSA1/pol/AL1/HC-PI), the first adhesive layer surface and the surface of laminate C on the first retardation layer side are bonded together, and laminate A2 (PET /AL3/QWP/PSA1/pol/AL1/HC-PI) was obtained.
PET was peeled off from the laminate A2 (AL3/QWP/PSA1/pol/AL1/HC-PI).
Next, a composition containing an epoxy compound (manufactured by ADEKA Co., Ltd., viscosity: 44 mPa·s) as an ultraviolet curable adhesive was applied onto the surface of the laminate B on the retardation layer side by a bar coating method, and the adhesive layer ( AD) was formed.
The surface of the laminate A2 on the third alignment film side and the surface of the laminate B coated with the ultraviolet curable adhesive were bonded together.
Next, ultraviolet rays (UVB) having an integrated light amount (integrated amount of light irradiation intensity in the wavelength range of 280 to 320 nm) of approximately 250 mJ/cm ² (measured value using a measuring device: UV Power Puck II manufactured by Fusion UV) were applied to the B side of the laminate. Optical laminates (TAC2/AL2/posiC/AD/AL3/QWP/PSA1/pol/AL1/HC-PI) were produced by side irradiation.

<Example 5>
An optical laminate was obtained in the same manner as in Example 1, except that the type and thickness of the second protective layer were changed to those shown in Table 1 (COP2). The results are shown in Table 1. In Table 1, COP means a cyclic olefin resin film.

<Example 6>
An optical laminate was obtained in the same manner as in Example 1, except that the thickness of the first protective layer was changed to the thickness (TAC4) shown in Table 1. The results are shown in Table 1.

<Comparative example 1>
When producing laminate B, an optical laminate was obtained in the same manner as in Example 1, except that the surface of the second protective layer was not subjected to corona treatment, and then the second protective layer was peeled from the optical laminate. . The results are shown in Table 1.

<Comparative example 2>
When manufacturing laminate A, the thickness of the first protective layer was changed to 50 μm (TAC5). Composition (D-1) was applied onto the polarizing layer of laminate A by a bar coating method and dried by heating in a drying oven at 80° C. for 1 minute. The obtained dried film was subjected to polarized UV irradiation treatment to form a third alignment film. The polarized UV treatment was performed using a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) under the condition that the cumulative amount of light measured at a wavelength of 365 nm was 100 mJ/cm ² . Further, the polarization direction of the polarized UV light was set at 45° with respect to the absorption axis of the polarizing layer.
Composition (B-1) was applied onto the third alignment film thus obtained by a bar coating method, dried by heating in a drying oven at 120° C. for 1 minute, and then cooled to room temperature. The obtained dried film was irradiated with ultraviolet rays at a cumulative light amount of 1000 mJ/cm ² (based on 365 nm) using the UV irradiation device described above to form a first retardation layer. The first retardation layer was a λ/4 plate.

Composition (D-1) was applied onto this first retardation layer by a bar coating method, and dried by heating in a drying oven at 90° C. for 1 minute to form a second alignment film. Thereafter, the composition (C-1) was coated on the second alignment film by a bar coating method, and after being heated and dried in a drying oven at 90°C for 1 minute, the cumulative amount of light was A second retardation layer was formed by irradiating ultraviolet light of 1000 mJ/cm ² (365 nm standard). The thickness of the obtained second retardation layer was measured using a laser microscope (OLS3000 manufactured by Olympus Corporation) and was found to be 1.8 μm. The second retardation layer was a positive C plate.

<Comparative example 3>
Comparative Example 2 was carried out in the same manner as in Comparative Example 2, except that the first protective layer was changed from TAC film to cyclic olefin resin film (ARTON, JSR Corporation, COP1), and the thickness of each layer was changed to the thickness shown in Table 1. An optical laminate was obtained. The results are shown in Table 1.

<Comparative example 4>
Example 1 except that the thickness of the first protective layer was changed to the thickness shown in Table 1 (TAC4), and the type and thickness of the second protective layer were changed to the type and thickness shown in Table 1 (COP2). An optical laminate was obtained in the same manner as above. The results are shown in Table 1.

10 optical laminate, 11 first protective layer, 12 polarizing layer, 13 first adhesive layer, 14 first retardation layer, 15 second adhesive layer, 16 second retardation layer, 17 second protective layer, 18 release film A, 19 Release film B, 20 First base material (release film C), 21 Release film D, 22 Release film E, 31 Laminate A, 32 Laminate B, 33 Laminate C, 34 First adhesive sheet, 35 Second adhesive sheet, 100 laminate, 501 stage, 502 stage.

Claims (3)

A first protective layer, a polarizing layer, a first adhesive layer, a first retardation layer, a second adhesive layer, a second retardation layer and a second protective layer are laminated in this order,
The first protective layer is a resin film that has been hard coated on the surface or both surfaces on which the polarizing layer is not formed,
The thickness of the first protective layer is 30 μm to 100 μm,
The thickness of the polarizing layer is 0.5 μm to 10 μm,
The thickness of the first adhesive layer is 1 μm to 15 μm,
The thickness of the first retardation layer is 0.5 μm to 5 μm,
The thickness of the second adhesive layer is 1 μm to 15 μm,
The thickness of the second retardation layer is 0.5 μm to 5 μm,
The thickness of the second protective layer is 15 μm to 60 μm,
The ratio (A/B) of the thickness (A) of the first protective layer to the thickness (B) of the second protective layer is 1 to 3.2,
The following formula (1) of the second protective layer:
Modified toughness = maximum stress x maximum strain (1)
[However, maximum stress and maximum strain indicate the stress and strain at the point of failure in the stress-strain curve, respectively.]
The modified toughness defined by is 280 MPa・% to 2753 MPa・%,
A bending device (manufactured by Science Town, STS-VRT) comprising a first stage and a second stage, and the distance (gap) between the first stage and the second stage was set to 5 mm (2.5R). -500), the optical laminate is bent 100,000 times or more when measured under the following measurement conditions.
[Measurement condition]
At an initial stage when the optical laminate is placed on the first stage and the second stage, the first stage and the second stage form the same plane. 90 degrees upward from the position of the end of the first stage facing the second stage and the position of the end of the second stage facing the first stage as the center of the rotation axis. The operation of closing the first stage and the second stage by rotating the first stage and opening the first stage and the second stage again is defined as one bending operation. This operation is repeated, and the number of times until a crack first appears in the optical laminate is defined as the number of bending times. The optical laminate according to claim 1, wherein the second protective layer has a modified toughness defined by the formula (1) of 2300 MPa·% or more. A display device comprising the optical laminate according to claim 1 or 2 .

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