JP7551014B1 - Optical laminate - Google Patents

Abstract

The present invention provides an optical laminate including a retardation plate having a plurality of liquid crystal retardation films, in which unevenness visually recognized from an oblique direction is reduced.
[Solution] An optical laminate comprising a first protective film, an adhesive layer, a polarizer, an adhesive layer, a second protective film, a first adhesive layer, a first liquid crystal retardation film, a second adhesive layer, and a second liquid crystal retardation film laminated adjacent to each other in this order, wherein the second protective film and the first adhesive layer satisfy formula (1) when the refractive index of the second protective film with respect to light having a wavelength of 589 nm is N _aII and the refractive index of the first adhesive layer with respect to light having a wavelength of 589 nm is N _bI , the first liquid crystal retardation film and the second liquid crystal retardation film each independently satisfy formula (2) or formula (3), and the second adhesive layer has a thickness of 2.8 μm to 20 μm.
|N _aII -N _bI |≦0.04...(1)
nx>ny≧nz...(2)
nx<ny≦nz...(3)
[Selected Figure] Figure 1

Description

The present invention relates to an optical laminate.

Conventionally, image display devices have adopted a method of placing a circular polarizer on the viewing side of the image display panel to suppress the decrease in visibility due to reflection of external light.

A circular polarizing plate is an optical laminate in which a linear polarizing plate and a retardation plate are laminated. In a circular polarizing plate, external light heading toward an image display panel is converted into linearly polarized light by the linear polarizing plate, and then converted into circularly polarized light by the subsequent retardation plate. Although the circularly polarized external light is reflected by the surface of the image display panel, the direction of rotation of the polarization plane is reversed during this reflection, and the light is converted into linearly polarized light by the retardation plate, and then blocked by the subsequent linear polarizing plate. As a result, the emission of external light to the outside is significantly suppressed.

For retardation plates, a configuration having a liquid crystal retardation film containing a cured liquid crystal compound is known (for example, Patent Documents 1 and 2). With such a configuration, it is possible to make the retardation plate thinner.

JP 2015-163935 A JP 2019-91030 A

In optical laminates equipped with retardation plates having multiple liquid crystal retardation films, unevenness could sometimes be seen from an oblique angle.

The present invention aims to provide an optical laminate that includes a retardation plate having multiple liquid crystal retardation films, and that reduces unevenness when viewed from an oblique direction.

The present invention provides the following optical laminate.
[1] An optical laminate comprising a first protective film, an adhesive layer, a polarizer, an adhesive layer, a second protective film, a first adhesive layer, a first liquid crystal retardation film, a second adhesive layer, and a second liquid crystal retardation film laminated adjacent to each other in this order,
The second protective film and the first adhesive layer have a refractive index of N _aII for light having a wavelength of 589 nm, and a refractive index of the first adhesive layer for light having a wavelength of 589 nm, which can be _expressed by the following formula (1):
|N _aII -N _bI |<0.1...(1)
Fulfilling
The first liquid crystal retardation film and the second liquid crystal retardation film each independently represent a compound represented by the following formula (2) or (3):
nx>ny≧nz...(2)
nx<ny≦nz...(3)
Fulfilling
The second adhesive layer has a thickness of 2.8 μm to 20 μm.
(In formulas (2) and (3), nx represents a principal refractive index in a direction parallel to a plane of the first liquid crystal retardation film or the second liquid crystal retardation film in an index ellipsoid formed by the first liquid crystal retardation film or the second liquid crystal retardation film, ny represents a refractive index in a direction parallel to the plane in the index ellipsoid and perpendicular to the direction of nx, and nz represents a refractive index in a direction perpendicular to the plane in the index ellipsoid.)
[2] The optical laminate according to [1], wherein the first adhesive layer has a thickness in the range of 1 μm to 3 μm.
[3] The optical laminate according to [1] or [2], wherein the refractive index N _bI of the first adhesive layer is 1.48 to 1.54.
[4] The optical laminate according to any one of [1] to [3], wherein the second adhesive layer has a refractive index of 1.50 to 1.57 with respect to light having a wavelength of 589 nm.
[5] The optical laminate according to any one of [1] to [4], wherein the second adhesive layer has a storage modulus at a temperature of 80° C. of 0.04 MPa or more.
[6] The optical laminate according to any one of [1] to [5], wherein the first adhesive layer has a storage modulus at a temperature of 80° C. of 0.02 GPa or more and 5 GPa or less.

The present invention provides an optical laminate that includes a retardation plate having multiple liquid crystal retardation films, and that reduces unevenness when viewed from an oblique direction.

FIG. 1 is a schematic cross-sectional view showing an example of an optical laminate of the present embodiment. FIG. 2 is a schematic cross-sectional view showing a specific example of a retardation plate. 3A to 3C are schematic diagrams illustrating a method for polishing an end face of the optical laminate of the present embodiment. 1 is a schematic cross-sectional view showing an example of an image display device according to an embodiment of the present invention.

Below, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment. In all of the drawings below, the scale of each component has been appropriately adjusted to make it easier to understand, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

[Optical laminate]
FIG. 1 is a schematic cross-sectional view showing an example of the optical laminate of the present embodiment. As shown in FIG. 1, the optical laminate 1 includes a first protective film 11, an adhesive layer 12, a polarizer 13, an adhesive layer 14, a second protective film 15, a first adhesive layer 21, a first liquid crystal retardation film 31, a second adhesive layer 34, and a second liquid crystal retardation film 32, which are laminated adjacent to each other in this order from the front side. In this specification, the linear polarizing plate 10 is a laminate consisting of the first protective film 11, the adhesive layer 12, the polarizer 13, the adhesive layer 14, and the second protective film 15. In this specification, the retardation plate 30 is a laminate consisting of the first liquid crystal retardation film 31, the second adhesive layer 34, and the second liquid crystal retardation film 32. The optical laminate 1 may be a circular polarizing plate.

In the optical laminate 1, the second protective film 15 and the first adhesive layer 21 satisfy the following formula (1), where the refractive index of the second protective film for light with a wavelength of 589 nm is N _aII and the refractive index of the first adhesive layer for light with a wavelength of 589 nm is N _bI .
|N _aII -N _bI |<0.1...(1)

In the optical laminate 1, a configuration that satisfies the above formula (1) can reduce interference unevenness that is visible from an oblique direction.

In the retardation plate 30, the first liquid crystal retardation film and the second liquid crystal retardation film are represented by the following formula (2) or formula (3):
nx>ny≧nz...(2)
nx<ny≦nz...(3)
Meet the following.
(In formulas (2) and (3), nx represents a principal refractive index in a direction parallel to a plane of the first liquid crystal retardation film or the second liquid crystal retardation film in an index ellipsoid formed by the first liquid crystal retardation film or the second liquid crystal retardation film, ny represents a refractive index in a direction parallel to the plane in the index ellipsoid and perpendicular to the direction of nx, and nz represents a refractive index in a direction perpendicular to the plane in the index ellipsoid.)

[First adhesive layer]
The first adhesive layer 21 is an attachment layer used to attach the retardation plate 30 and the linear polarizer 10 to each other.

The first adhesive layer 21 is a pressure-sensitive adhesive layer formed using a pressure-sensitive adhesive composition, or an adhesive layer formed using an adhesive composition, and from the viewpoint of processability of the end surface of the optical laminate, it is preferable that the first adhesive layer 21 is an adhesive layer formed using an adhesive composition.

When the first adhesive layer 21 is an adhesive layer, from the viewpoint of handling in the lamination process, the thickness is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more. Also, it is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. When the first adhesive layer 21 is an adhesive layer, from the viewpoint of adhesion and curing properties, the thickness is preferably 0.1 μm or more, more preferably 0.4 μm or more, and even more preferably 1 μm or more. Also, for the same reason, it is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less.

When the first adhesive layer 21 is formed of an adhesive layer, the storage modulus at a temperature of 80 ° C. may be 0.01 MPa or more and 0.8 MPa or less, preferably 0.02 MPa or more and 0.4 MPa or less, more preferably 0.03 MPa or more and 0.2 MPa or less, and even more preferably 0.04 MPa or more and 0.1 MPa or less. When the first adhesive layer 21 is formed of an adhesive layer, the storage modulus at a temperature of 80 ° C. may be 0.01 GPa or more and 10 GPa or less, preferably 0.02 GPa or more and 5 GPa or less, more preferably 0.1 GPa or more and 3 GPa or less, and even more preferably 0.5 GPa or more and 2 GPa or less. When the storage modulus at a temperature of 80 ° C. of the first adhesive layer 21 is in the above range, the end face of the optical laminate 1 can be easily polished, and dirt when the end face of the optical laminate 1 is polished can be reduced. In this specification, the storage modulus of the first adhesive layer 21 can be measured by the method described in the Examples below.

When the first adhesive layer 21 is formed of an adhesive layer, the storage modulus at a temperature of 23 ° C. may be 0.01 MPa or more and 1 MPa or less, preferably 0.02 MPa or more and 0.5 MPa or less, more preferably 0.03 MPa or more and 0.3 MPa or less, and even more preferably 0.05 MPa or more and 0.15 MPa or less. When the first adhesive layer 21 is formed of an adhesive layer, the storage modulus at a temperature of 23 ° C. may be 0.01 GPa or more and 10 GPa or less, preferably 0.1 GPa or more and 5 GPa or less, more preferably 0.3 GPa or more and 4 GPa or less, and even more preferably 0.5 GPa or more and 3 GPa or less. When the storage modulus at a temperature of 23 ° C. of the first adhesive layer 21 is in the above range, the end face of the optical laminate 1 can be easily polished, and dirt when the end face of the optical laminate 1 is polished can be reduced. In this specification, the storage modulus of the first adhesive layer 21 can be measured by the method described in the Examples below.

The first adhesive layer 21 has a refractive index N _bI for light having a wavelength of 589 nm of preferably 1.46 or more, more preferably 1.48 or more, and even more preferably 1.50 or more. The refractive index N _bI for light having a wavelength of 589 nm is preferably 1.56 or less, more preferably 1.54 or less, and even more preferably 1.52 or less. When the refractive index of the first adhesive layer 21 is in the above range, interference unevenness occurring at the interface between the first liquid crystal retardation film 31 and the first adhesive layer 21 and the interface between the second protective film 15 and the first adhesive layer 21 is suppressed, and interference unevenness viewed from an oblique direction of the optical laminate 1 can be further reduced.

[Second adhesive layer]
The second adhesive layer 34 is a layer that is responsible for bonding the first liquid crystal retardation film 31 and the second liquid crystal retardation film 32. The second adhesive layer 34 is a pressure-sensitive adhesive layer formed using a pressure-sensitive adhesive composition, or an adhesive layer formed using an adhesive composition, and is preferably an adhesive layer formed using an adhesive composition from the viewpoint of processability of the end face of the optical laminate. The thickness of the second adhesive layer 34 is 2.8 μm or more, preferably 3.0 μm or more, and more preferably 3.2 μm or more, from the viewpoint of reducing interference unevenness viewed from an oblique direction. The thickness of the second adhesive layer 34 is 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less, from the viewpoint of processability and bendability of the optical laminate. When the thickness of the second adhesive layer 34 is in the above range, interference unevenness viewed from an oblique direction of the optical laminate 1 can be reduced.

When the second adhesive layer 34 is formed of an adhesive layer, the storage modulus at a temperature of 80 ° C. may be 0.01 MPa or more and 0.8 MPa or less, preferably 0.02 MPa or more and 0.4 MPa or less, more preferably 0.03 MPa or more and 0.2 MPa or less, and even more preferably 0.04 MPa or more and 0.1 MPa or less. When the second adhesive layer 34 is formed of an adhesive layer, the storage modulus at a temperature of 80 ° C. may be 0.001 GPa or more and 5 GPa or less, preferably 0.005 GPa or more and 3 GPa or less, more preferably 0.1 GPa or more and 1 GPa or less, and even more preferably 0.02 GPa or more and 0.5 GPa or less. When the storage modulus at a temperature of 80 ° C. of the second adhesive layer 34 is in the above range, the end face of the optical laminate 1 can be easily polished, and dirt when the end face of the optical laminate 1 is polished can be reduced. In this specification, the storage modulus of the second adhesive layer 34 can be measured by the method described in the Examples below.

When the second adhesive layer 34 is formed of an adhesive layer, the storage modulus at a temperature of 23 ° C. may be 0.01 MPa or more and 1 MPa or less, preferably 0.02 MPa or more and 0.5 MPa or less, more preferably 0.03 MPa or more and 0.3 MPa or less, and even more preferably 0.05 MPa or more and 0.15 MPa or less. When the second adhesive layer 34 is formed of an adhesive layer, the storage modulus at a temperature of 23 ° C. may be 0.01 GPa or more and 10 GPa or less, preferably 0.1 GPa or more and 5 GPa or less, more preferably 0.3 GPa or more and 4 GPa or less, and even more preferably 0.5 GPa or more and 3 GPa or less. When the storage modulus at a temperature of 23 ° C. of the second adhesive layer 34 is in the above range, the end face of the optical laminate 1 can be easily polished, and dirt when the end face of the optical laminate 1 is polished can be reduced. In this specification, the storage modulus of the second adhesive layer 34 can be measured by the method described in the Examples below. The method for measuring the storage modulus of the second adhesive layer 34 differs between the adhesive layer and the pressure-sensitive adhesive layer, as shown in the Examples below.

The second adhesive layer 34 preferably has a refractive index of 1.48 or more for light with a wavelength of 589 nm, more preferably 1.50 or more, and even more preferably 1.52 or more. The refractive index of light with a wavelength of 589 nm is preferably 1.59 or less, more preferably 1.57 or less, and even more preferably 1.55 or less. By having the refractive index of the second adhesive layer 34 in the above range, interference unevenness occurring between the interface between the first liquid crystal retardation film 31 and the second adhesive layer 34 and the interface between the second liquid crystal retardation film 32 and the second adhesive layer 34 is suppressed, and the interference unevenness visible from an oblique direction of the optical laminate 1 can be further reduced, and the reflectance of the optical laminate 1 can be reduced.

The second adhesive layer 34 is preferably an adhesive layer, since it is easier to form a layer that satisfies the above numerical range of storage modulus with an adhesive composition than with a pressure-sensitive adhesive composition.

<Adhesive Composition>
In the optical laminate 1, the adhesive composition can be used as a material for forming the adhesive layer 12, the adhesive layer 14, the first adhesive layer 21, and the second adhesive layer 34. Examples of the adhesive composition include an aqueous adhesive composition, a curable adhesive composition that is cured by heating or irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays, and the like. Examples of the aqueous adhesive composition include a composition in which a polyvinyl alcohol-based resin or a urethane resin is dissolved in water as the main component, and a composition in which a polyvinyl alcohol-based resin or a urethane resin is dispersed in water as the main component. The aqueous adhesive composition may further contain a curable component or a crosslinking agent such as a polyhydric aldehyde, a melamine-based compound, a zirconia compound, a zinc compound, a glyoxal compound, or a water-soluble epoxy resin. Examples of the aqueous adhesive composition include the adhesive composition described in JP-A-2010-191389, the adhesive composition described in JP-A-2011-107686, the composition described in JP-A-2020-172088, and the composition described in JP-A-2005-208456.

The curable adhesive composition is preferably an active energy ray curable adhesive composition that contains a curable (polymerizable) compound as a main component and is cured by irradiation with active energy rays. Examples of active energy ray curable adhesive compositions include cationic polymerization adhesive compositions that contain a cationic polymerizable compound as a curable compound, radical polymerization adhesive compositions that contain a radical polymerizable compound as a curable compound, and hybrid adhesive compositions that contain both a cationic polymerizable compound and a radical polymerizable compound as curable compounds.

The cationically polymerizable compound is a compound or oligomer that undergoes a cationic polymerization reaction and hardens when exposed to active energy rays such as ultraviolet light, visible light, electron beams, and X-rays, or when heated. Specific examples of the cationically polymerizable compound include epoxy compounds, oxetane compounds, and vinyl compounds.
Examples of epoxy compounds include alicyclic epoxy compounds (compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule) such as 3',4'-epoxycyclohexylmethyl and 3,4-epoxycyclohexanecarboxylate; aromatic epoxy compounds (compounds having an aromatic ring and an epoxy group in the molecule) such as diglycidyl ether of bisphenol A; and aliphatic epoxy compounds (compounds having at least one oxirane ring bonded to an aliphatic carbon atom in the molecule) such as 2-ethylhexyl glycidyl ether and 1,4-butanediol diglycidyl ether.
Examples of the oxetane compound include compounds having one or more oxetane rings in the molecule, such as 3-ethyl-3-{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane.
The cationic polymerization adhesive composition preferably contains a cationic polymerization initiator. The cationic polymerization initiator may be a thermal cationic polymerization initiator or a photo-induced cationic polymerization initiator. Examples of the cationic polymerization initiator include aromatic diazonium salts such as benzenediazonium hexafluoroantimonate; aromatic iodonium salts such as diphenyliodonium tetrakis(pentafluorophenyl)borate; aromatic sulfonium salts such as triphenylsulfonium hexafluorophosphate; and iron-arene complexes such as xylene-cyclopentadienyl iron (II) hexafluoroantimonate. The content of the cationic polymerization initiator is usually 0.1 to 10 parts by mass relative to 100 parts by mass of the cationic polymerizable compound. The cationic polymerization initiator may contain two or more types.
Examples of the cationic polymerization adhesive composition include the cationic polymerizable compositions described in JP 2016-126345 A, WO 2019/10315 A, and JP 2021-113969 A.

The radical polymerizable compound is a compound or oligomer that undergoes a radical polymerization reaction and hardens when exposed to active energy rays such as ultraviolet light, visible light, electron beams, and X-rays or when heated, and specifically includes a compound having an ethylenically unsaturated bond. Examples of the compound having an ethylenically unsaturated bond include a (meth)acrylic compound having one or more (meth)acryloyl groups in the molecule, and a vinyl compound having one or more vinyl groups in the molecule.
Examples of the (meth)acrylic compound include (meth)acrylate monomers having at least one (meth)acryloyloxy group in the molecule, (meth)acrylamide monomers, and (meth)acryloyl group-containing compounds such as (meth)acrylic oligomers obtained by reacting two or more functional group-containing compounds and having at least two (meth)acryloyl groups in the molecule. In this specification, (meth)acryloyl means either acryloyl or methacryloyl.
The radical polymerization adhesive composition preferably contains a radical polymerization initiator. The radical polymerization initiator may be a thermal radical polymerization initiator or a photoradical polymerization initiator. Examples of the radical polymerization initiator include acetophenone-based initiators such as acetophenone and 3-methylacetophenone; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone, and 4,4'-diaminobenzophenone; benzoin ether-based initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone-based initiators such as 4-isopropylthioxanthone; xanthone, fluorenone, and the like. The content of the radical polymerization initiator is usually 0.1 to 10 parts by mass relative to 100 parts by mass of the radical polymerizable compound. Two or more types of radical polymerization initiators may be included.
Examples of radical polymerization adhesive compositions include the radical polymerizable compositions described in JP 2016-126345 A, JP 2016-153474 A, and WO 2017/183335 A.

The active energy ray-curable adhesive composition may contain additives such as ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow control agents, plasticizers, defoamers, antistatic agents, leveling agents, and solvents, as necessary.

The first liquid crystal retardation film 31 and the second liquid crystal retardation film 32 can be bonded to each other with an adhesive layer by applying an adhesive composition to at least one of the bonding surfaces selected from the respective bonding surfaces of the two layers, stacking the two films with the coating layer of the adhesive composition therebetween, pressing the films together from above and below using a lamination roll or the like, and then curing the films by irradiating them with active energy rays or by heating the films.
Before forming the coating layer of the adhesive layer, at least one of the bonding surfaces of the two layers may be subjected to an adhesion enhancing treatment such as saponification treatment, corona treatment, plasma treatment, primer treatment, anchor coating treatment, etc.
To form a coating layer of the adhesive composition, various coating methods can be used, such as a die coater, a comma coater, a gravure coater, a wire bar coater, or a doctor blade coater.

The light irradiation intensity when irradiating with active energy rays is determined for each composition of the active energy ray-curable adhesive composition and is not particularly limited, but is preferably 10 mW/ ^cm2 or more and 1,000 mW/ ^cm2 or less. The irradiation intensity is preferably an intensity in a wavelength region effective for activating a photocationic polymerization initiator or a photoradical polymerization initiator. It is preferable to irradiate once or multiple times with such light irradiation intensity, and the accumulated light amount is preferably 10 mJ/ ^cm2 or more, more preferably 100 mJ/ ^cm2 or more and 1,000 mJ/ ^cm2 or less.
The light source used for polymerizing and curing the active energy ray-curable adhesive composition is not particularly limited, but examples 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 chemical lamp, a black light lamp, a microwave excited mercury lamp, and a metal halide lamp.

<Adhesive composition>
In the optical laminate 1, the adhesive composition can be used as a material for forming the first adhesive layer 21 and the second adhesive layer 34. As the adhesive composition, any conventionally known adhesive composition having excellent optical transparency can be used without any particular limitation, and for example, an adhesive composition having a base polymer such as an acrylic resin, a urethane resin, a silicone resin, or a polyvinyl ether resin can be used. In addition, an active energy ray curable adhesive composition, a heat curable adhesive composition, or the like may be used. Among these, an adhesive composition having an acrylic resin as a base polymer, which is excellent in transparency, adhesive strength, removability, weather resistance, heat resistance, and the like, is preferable.
The pressure-sensitive adhesive composition may further contain a crosslinking agent, a silane compound, an antistatic agent, and the like.

((Meth)acrylic resin)
The (meth)acrylic resin contained in the pressure-sensitive adhesive composition is preferably a polymer (hereinafter also referred to as a "(meth)acrylic acid ester polymer") having as its main component (e.g., containing 50 parts by mass or more per 100 parts by mass of the structural unit of the (meth)acrylic resin) a structural unit derived from a (meth)acrylic acid alkyl ester represented by the following formula (I) (hereinafter also referred to as "structural unit (I)"):
In this specification, the (meth)acrylic resin means either an acrylic resin or a methacrylic resin, and the "(meth)" in (meth)acrylate has the same meaning.

［式中、Ｒ^１０は、水素原子またはメチル基を表し、Ｒ^２０は、炭素数１～２０のアルキル基を表し、前記アルキル基は直鎖状、分岐状または環状のいずれの構造を有していてもよく、前記アルキル基の水素原子は、炭素数１～１０のアルコキシ基で置き換わっていてもよい。］

[In the formula, R ¹⁰ represents a hydrogen atom or a methyl group, R ²⁰ represents an alkyl group having 1 to 20 carbon atoms, the alkyl group may have any of a linear, branched, or cyclic structure, and the hydrogen atom of the alkyl group may be replaced by an alkoxy group having 1 to 10 carbon atoms.]

Examples of the (meth)acrylic acid ester represented by formula (I) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, i-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and n- Examples of the alkyl acrylate containing an alkoxy group include 2-methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and the like. Among these, it is preferable to include n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate, n- and i-nonyl (meth)acrylate, n-decyl (meth)acrylate, i-decyl (meth)acrylate, n-dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, and t-butyl (meth)acrylate. Specific examples of the alkyl acrylate containing an alkoxy group include 2-methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and the like. Among these, it is preferable to include n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate, and it is particularly preferable to include n-butyl (meth)acrylate.

The (meth)acrylic acid ester polymer may contain a structural unit derived from a monomer other than the structural unit (I). The structural unit derived from the other monomer may be one type or two or more types. Examples of other monomers that the (meth)acrylic acid ester polymer may contain include a monomer having a polar functional group, a monomer having an aromatic group, and an acrylamide monomer.

Monomers having a polar functional group include (meth)acrylates having a polar functional group. Examples of the polar functional group include a hydroxy group; a carboxy group; an amino group substituted with an alkyl group having 1 to 6 carbon atoms or an unsubstituted amino group; and a heterocyclic group such as an epoxy group.

The content of structural units derived from monomers having polar functional groups in the (meth)acrylic acid ester polymer is preferably 10 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, even more preferably 0.5 parts by mass or more and 5 parts by mass or less, and particularly preferably 1 part by mass or more and 5 parts by mass or less, relative to 100 parts by mass of all structural units of the (meth)acrylic acid ester polymer.

Examples of monomers having an aromatic group include (meth)acrylic acid esters having one (meth)acryloyl group and one or more aromatic rings (e.g., benzene ring, naphthalene ring, etc.) in the molecule, and having a phenyl group, a phenoxyethyl group, or a benzyl group. By including these structural units, it is possible to suppress the white void phenomenon that occurs in optical laminates in high temperature and high humidity environments.

The content of structural units derived from monomers having an aromatic group in the (meth)acrylic acid ester polymer is preferably 20 parts by mass or less, more preferably 4 parts by mass or more and 20 parts by mass or less, and even more preferably 4 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of all structural units of the (meth)acrylic acid ester polymer.

Examples of acrylamide monomers include N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, and N-(2-methylpropoxymethyl)acrylamide. By including these structural units, it is possible to suppress the bleeding out of additives such as antistatic agents, which will be described later.

Furthermore, structural units derived from monomers other than structural unit (I) may include structural units derived from styrene-based monomers, structural units derived from vinyl-based monomers, structural units derived from monomers having multiple (meth)acryloyl groups in the molecule, and the like.

The weight average molecular weight (hereinafter, simply referred to as "Mw") of the (meth)acrylic resin (1) is preferably 500,000 to 2,500,000. When the weight average molecular weight is 500,000 or more, the durability of the first adhesive layer in a high temperature and high humidity environment can be improved. When the weight average molecular weight is 2,500,000 or less, the operability when applying a coating liquid containing the adhesive composition is improved. The molecular weight distribution (Mw/Mn), which is expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (hereinafter, simply referred to as "Mn"), is usually 2 to 10. In this specification, "weight average molecular weight" and "number average molecular weight" are polystyrene-equivalent values measured by gel permeation chromatography (GPC).

When the (meth)acrylic resin is dissolved in ethyl acetate to form a solution with a concentration of 20% by mass, the viscosity at 25°C is preferably 20 Pa·s or less, and more preferably 0.1 to 15 Pa·s. If the viscosity of the (meth)acrylic resin at 25°C is within the above range, it contributes to improved durability and reworkability of the optical laminate including the pressure-sensitive adhesive layer formed from the resin. The viscosity can be measured using a Brookfield viscometer.

The glass transition temperature (Tg) of the (meth)acrylic resin is, for example, −60 to 20° C., preferably −50 to 15° C., more preferably −45 to 10° C., and even more preferably −40 to 0° C. The glass transition temperature can be measured by a differential scanning calorimeter (DSC).

The (meth)acrylic resin may contain two or more types of (meth)acrylic acid ester polymers. Examples of such (meth)acrylic acid ester polymers include (meth)acrylic acid ester polymers having a relatively low molecular weight, such as those having a weight average molecular weight in the range of 50,000 to 300,000, that are mainly composed of structural units (I) derived from the (meth)acrylic acid ester.

(Meth)acrylic resins can usually be produced by known polymerization methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. In producing (meth)acrylic resins, polymerization is usually carried out in the presence of a polymerization initiator. The amount of polymerization initiator used is usually 0.001 to 5 parts by mass per 100 parts by mass of the total of all monomers constituting the (meth)acrylic resin. (Meth)acrylic resins can also be produced by a method of polymerization using active energy rays such as ultraviolet rays.

(Crosslinking Agent)
The pressure-sensitive adhesive composition preferably contains a crosslinking agent. Examples of the crosslinking agent include conventional crosslinking agents (e.g., isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds, peroxides, etc.), and in particular, from the viewpoints of the pot life of the pressure-sensitive adhesive composition, crosslinking speed, and durability of the polarizing plate, it is preferable to use an isocyanate compound.

The isocyanate compound is a compound having at least two isocyanato groups (-NCO) in the molecule. Specific examples include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Other examples include adducts obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylolpropane, and dimers and trimers of these isocyanate compounds. Two or more types of isocyanate compounds may be combined.

The proportion of the crosslinking agent is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 1 part by mass, per 100 parts by mass of the (meth)acrylic resin.

(Silane Compound)
The pressure-sensitive adhesive composition may further contain a silane compound.
Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethoxydimethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.
The silane compound may also contain an oligomer derived from the above silane compound.

The content of the silane compound in the adhesive composition is usually 0.01 to 10 parts by mass, and preferably 0.05 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic resin. When the content of the silane compound is 0.01 parts by mass or more, the adhesion between the adhesive layer and the adherend tends to be improved, and when the content is 10 parts by mass or less, bleeding out of the silane compound from the adhesive layer tends to be suppressed.

(Antistatic Agent)
The pressure-sensitive adhesive composition may further include an antistatic agent. Examples of the antistatic agent include known ones, and ionic antistatic agents are preferred. Examples of the cationic component constituting the ionic antistatic agent include organic cations and inorganic cations. Examples of the organic cation include pyridinium cation, imidazolium cation, ammonium cation, sulfonium cation, phosphonium cation, etc. Examples of the inorganic cation include alkali metal cations such as lithium cation, potassium cation, sodium cation, and cesium cation, and alkaline earth metal cations such as magnesium cation and calcium cation. Examples of the anionic component constituting the ionic antistatic agent may be either inorganic anion or organic anion, but an anionic component containing a fluorine atom is preferred in terms of excellent antistatic performance. Examples of the anion component containing a fluorine atom include a hexafluorophosphate anion (PF ₆ ⁻ ), a bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ⁻ ], and a bis(fluorosulfonyl)imide anion [(FSO ₂ ) ₂ N ⁻ ] anion.
In view of excellent stability over time of the antistatic performance of the pressure-sensitive adhesive composition, an ionic antistatic agent that is solid at room temperature is preferred.
The content of the antistatic agent is, for example, 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, and more preferably 1 to 7 parts by mass, relative to 100 parts by mass of the (meth)acrylic resin.

The adhesive composition may contain one or more additives such as ultraviolet absorbers, solvents, crosslinking catalysts, tackifiers, and plasticizers. It is also useful to incorporate an ultraviolet-curable compound into the adhesive composition, form an adhesive layer, and then irradiate the adhesive with ultraviolet light to cure the layer, thereby forming a harder adhesive layer.

The adhesive layer can be formed, for example, by dissolving or dispersing the adhesive composition in a solvent to form a solvent-containing adhesive composition, which is then applied to the surface of the layer on which the adhesive layer is to be formed, and then drying.

[Linear polarizing plate]
The linear polarizing plate 10 is a film having anisotropic light absorption properties, and is generally a film including a polarizer 13 made of a polarizing film or a polarizing membrane in which a dichroic dye is uniaxially oriented. In order to uniaxially align the dichroic dye, the linear polarizing plate 10 can be produced from a film uniaxially stretched in a state in which iodine or an organic dichroic dye is impregnated in a polymer such as PVA, or a polarizing membrane formed by orienting a dichroic dye and a polymerizable liquid crystal compound. That is, the linear polarizing plate 10 exhibits a polarizing function by anisotropically absorbing light by the dichroic dye encapsulated in the polymer of the stretched polymer or the polymerizable liquid crystal compound.

The polarization performance of the linear polarizing plate can be measured using a spectrophotometer. For example, the transmittance (T1) in the transmission axis direction (direction perpendicular to the orientation) and the transmittance (T2) in the absorption axis direction (direction of orientation) in the visible light wavelength range of 380 nm to 780 nm can be measured by a double beam method using a device in which a prism polarizer is set in a spectrophotometer. The polarization performance in the visible light range can be calculated as the luminosity-corrected single transmittance (Ty) and luminosity-corrected polarization degree (Py) by calculating the single transmittance and the degree of polarization at each wavelength using the following formulas (Formula 1) and (Formula 2), and further performing luminosity correction using a 2-degree visual field (C light source) according to JIS Z 8701. Similarly, the chromaticity a ^* and b ^* in the L ^* a ^* b ^* (CIE) color system are calculated from the transmittance measured in the same manner using the color matching function of the C light source to obtain the hue of the linear polarizer alone (single hue), the hue of linear polarizers arranged in parallel (parallel hue), and the hue of linear polarizers arranged perpendicularly (orthogonal hue). The closer the values of ^a* and b ^* are to 0, the more neutral the hue is.
Single-piece transmittance (%)=(T1+T2)/2 (Equation 1)
Degree of polarization (%) = (T1-T2)/(T1+T2)×100 (Formula 2)

The luminosity-corrected polarization degree Py of a linear polarizer is usually 80% or more, preferably 90% or more, more preferably 95% or more, even more preferably 98% or more, and particularly preferably 99% or more. If it is 99.9% or more, it can be suitably used in liquid crystal displays. Increasing the luminosity-corrected polarization degree Py of a linear polarizer is advantageous in enhancing the anti-reflection function of the optical laminate. If the luminosity-corrected polarization degree Py is less than 80%, it may not be able to fulfill its anti-reflection function when used as an anti-reflection film.

The higher the luminosity-corrected single transmittance Ty of the linear polarizer, the greater the clarity of the white display. However, as can be seen from the relationship between (Equation 1) and (Equation 2), if the single transmittance is too high, there is a problem that the degree of polarization decreases. Therefore, it is preferably 30% to 60%, more preferably 35% to 55%, even more preferably 38% to 50%, and even more preferably 40% to 45%. If the luminosity-corrected single transmittance Ty is too high, the luminosity-corrected polarization degree Py will be too low, and the anti-reflection function may be insufficient when used as an anti-reflection film.

The linear polarizing plate includes a first protective film 11 and a second protective film 15 on both sides of a polarizer 13. Thermoplastic resin films can be used as the protective films 11 and 15. The polarizer 13 and the protective films 11 and 15 are laminated via an adhesive layer. The film made of a thermoplastic resin may be subjected to a surface treatment (e.g., corona treatment, etc.) to improve adhesion with the polarizer 13, and a thin layer such as a primer layer (also called an undercoat layer) may be formed.

The thermoplastic resin constituting the thermoplastic resin film is preferably a transparent film, and examples thereof include cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamide; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having cyclo- and norbornene structures (also called norbornene resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins, and the like. Among these, the thermoplastic resin film is preferably a cyclic polyolefin resin film, a cellulose ester resin film, a polyester resin film, or a (meth)acrylic resin film. Among these, the protective films 11 and 15 are preferably resin films made of cellulose resins such as triacetyl cellulose and cyclic polyolefin resins having cyclo- and norbornene structures from the viewpoint of the balance of optical properties, processability, and economic efficiency, and in particular, the second protective film 15 is preferably a triacetyl cellulose (TAC) film from the viewpoint of refractive index.

The thickness of the protective films 11 and 15 is preferably 3 μm to 60 μm, more preferably 5 μm to 40 μm, and even more preferably 10 μm to 30 μm.

The protective films 11 and 15 may be a thermoplastic resin film having a hard coat layer formed thereon. The hard coat layer may be formed on one side of the thermoplastic resin film, or on both sides. By providing the hard coat layer, the thermoplastic resin film can be improved in hardness and scratch resistance. The hard coat layer is, for example, a cured layer of an active energy ray curable resin, preferably an ultraviolet ray curable resin. Examples of ultraviolet ray curable resins include (meth)acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The hard coat layer may contain additives to improve strength. The additives are not particularly limited, and examples include inorganic fine particles, organic fine particles, and mixtures thereof.

The adhesive layer used to laminate the polarizer 13 and the protective films 11 and 15 is formed using the adhesive composition. Examples of adhesive compositions include aqueous adhesive compositions and curable adhesive compositions that are cured by heating or by irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays. When an aqueous adhesive composition is used, from the viewpoints of adhesion and processability, the film thickness is preferably in the range of 0.01 μm to 1.0 μm, more preferably in the range of 0.02 μm to 0.5 μm, and even more preferably in the range of 0.03 μm to 0.3 μm.

When the refractive index of the second protective film 15 for light having a wavelength of 589 nm is N _aII , the absolute value of the difference between the refractive index of the first adhesive layer for light having a wavelength of 589 nm and N _bI is expressed by the following formula (1):
|N _aII -N _bI |<0.1...(1)
Configure it to satisfy the following.
From the viewpoint of reducing interference unevenness visible from an oblique direction to a higher level, the absolute value of the difference between _NaII and _NbI is preferably 0.08 or less, more preferably 0.06 or less, and even more preferably 0.04 or less.

The refractive index _NaII of the second protective film 15 is preferably 1.46 or more, more preferably 1.47 or more, and even more preferably 1.48 or more. The refractive index _NaII for light with a wavelength of 589 nm is preferably 1.56 or less, more preferably 1.54 or less, and even more preferably 1.52 or less. When the refractive index of the protective film 15 is in the above range, interference unevenness occurring between the interface between the second protective film 15 and the first adhesive layer 21 is suppressed, and interference unevenness viewed from an oblique direction of the optical laminate 1 can be further reduced.

<Polarizing film>
A polarizing film, that is, a film obtained by uniaxially stretching a polymer such as a polyvinyl alcohol-based resin film (PVA) impregnated with iodine or an organic dichroic dye, can usually be produced through a process of uniaxially stretching a polyvinyl alcohol-based resin film, a process of dyeing the polyvinyl alcohol-based resin film with a dichroic dye such as iodine to adsorb the dichroic dye, a process of treating the polyvinyl alcohol-based resin film with the adsorbed dichroic dye with a crosslinking agent such as an aqueous boric acid solution, and a process of washing with water after the treatment with the crosslinking agent such as an aqueous boric acid solution. The polarizing film may contain a crosslinking agent.

The thickness of the polarizing film is usually 30 μm or less, preferably 18 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The thickness is usually 1 μm or more, for example, 5 μm or more.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing with a dichroic dye. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before or during the boric acid treatment. Of course, the uniaxial stretching can be performed in the multiple stages shown here. For the uniaxial stretching, a method of uniaxially stretching in the film transport direction between rolls with different peripheral speeds, a method of uniaxially stretching in the film transport direction using a heated roll, or a method of stretching in the width direction using a tenter can be used. The uniaxial stretching may be performed by dry stretching in the air, or by wet stretching in a state in which the polyvinyl alcohol-based resin film is swollen using a solvent such as water. The stretching ratio is usually about 3 to 8 times. In addition, an aqueous solution containing polyvinyl alcohol may be applied to the thermoplastic resin film, followed by drying, and then stretched together with the thermoplastic resin film by the above method.

Dyeing of a polyvinyl alcohol-based resin film with a dichroic dye can be carried out, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. Specific examples of the dichroic dye that can be used include iodine and dichroic organic dyes.

<Polarizing film>
A polarizing film, i.e., an optically anisotropic layer containing a polymer of a polymerizable liquid crystal compound containing a dichroic dye, can be suitably used for, for example, flexible display applications, since the hue can be arbitrarily controlled, the thickness can be significantly reduced, and the layer is non-shrinkable since it is not stretched or relaxed by heat.

The polarizing film is formed by applying a polarizing film-forming composition onto an alignment film formed on a substrate as necessary, and orienting the dichroic dye contained in the polarizing film-forming composition. The polarizing film has a thickness of 0.1 μm to 5 μm, more preferably 0.3 μm to 4 μm, and even more preferably 0.5 μm to 3 μm. If the film thickness is thinner than this range, the necessary light absorption may not be obtained, and if the film thickness is thicker than this range, the alignment control force of the alignment film decreases, and alignment defects tend to occur easily. In addition, the polarizing film-forming composition may further contain a solvent, a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, an adhesion improver, and the like.

In an optically anisotropic layer in which a dichroic dye and a polymerizable liquid crystal compound are oriented horizontally relative to the substrate surface, the ratio (dichroic ratio) of the absorbance A1 (λ) in the orientation direction for light with a wavelength of λ nm to the absorbance A2 (λ) in the vertical direction within the orientation plane is preferably 7 or more, more preferably 20 or more, and even more preferably 40 or more. The higher this value, the better the absorption selectivity of the polarizing plate. Although it depends on the type of dichroic dye, in the case of a liquid crystal cured film cured in a nematic liquid crystal phase state, the ratio is about 5 to 10.

By mixing two or more dichroic dyes with different absorption wavelengths, it is possible to produce polarizing films of various hues, and to produce polarizing films that absorb the entire visible light range. By producing polarizing films with such absorption properties, they can be used in a variety of applications.

<Polarizing film; polymerizable liquid crystal compound>
The polymerizable liquid crystal compound is a compound having a polymerizable group and having liquid crystal properties (hereinafter, also referred to as a polymerizable liquid crystal). The polymerizable group means a group involved in a polymerization reaction, and the polymerizable liquid crystal compound is a compound having a polymerizable group and a liquid crystal property (hereinafter, also referred to as a polymerizable liquid crystal). Here, the photopolymerizable group refers to a group that can be involved in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator described later. The polymerizable group is , vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, etc. Among them, acryloyloxy group, methacryloyloxy group The liquid crystallinity may be thermotropic or lyotropic, but when mixed with a dichroic dye described later, it is preferred to use a thermotropic liquid crystal or a lyotropic liquid crystal. The polymerizable liquid crystal compound may be a monomer or a polymer obtained by polymerizing a dimer or higher.

When the polymerizable liquid crystal compound 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. From the viewpoint of being able to exhibit high dichroism, the liquid crystal state exhibited by the polymerizable liquid crystal compound is preferably a smectic phase, and a high-order smectic phase is more preferable from the viewpoint of improving performance. Among them, a high-order smectic liquid crystal compound that forms a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase, or a smectic L phase is more preferable, and a high-order smectic liquid crystal compound that forms a smectic B phase, a smectic F phase, or a smectic I phase is even more preferable. If the liquid crystal phase formed by the polymerizable liquid crystal is one of these high-order smectic phases, a polarizing film with higher polarization performance can be manufactured. Furthermore, such polarizing films with high polarizing performance are those that, in X-ray diffraction measurements, show Bragg peaks resulting from higher-order structures such as hexatic and crystalline phases. The Bragg peaks are peaks resulting from the periodic structure of molecular orientation, and films with periodic intervals of 3 to 6 Å can be obtained. From the viewpoint of obtaining higher polarization characteristics, it is preferable for the polarizing film of the present invention to contain a polymer of the polymerizable liquid crystal oriented in a smectic phase state.

As the polymerizable liquid crystal compound, one type may be used alone, or two or more types may be used in combination. The polymerizable liquid crystal composition containing other compounds described later may contain other polymerizable liquid crystal compounds other than the polymerizable liquid crystal compound as long as the effect of the present invention is not impaired. From the viewpoint of obtaining a polarizing film with a high degree of alignment order, the ratio of the polymerizable liquid crystal compound to the total mass of all polymerizable liquid crystal compounds contained in the polymerizable liquid crystal composition is preferably 51% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

The content of the polymerizable liquid crystal compound in the polarizing film-forming composition of the present invention is preferably 40 to 99.9% by mass, more preferably 60 to 99% by mass, and even more preferably 70 to 99% by mass, based on the solid content of the polymerizable liquid crystal composition. When the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to be high. In this specification, the solid content refers to the total amount of components excluding the solvent from the polymerizable liquid crystal composition.

<Polarizing film; dichroic dye>
A dichroic dye is a dye that has different absorbance in the long axis direction of the molecule and in the short axis direction. A dichroic dye has the 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 them, azo dyes are preferable. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakis azo dyes, and stilbene azo dyes, and bisazo dyes and trisazo dyes are preferable. The dichroic dyes may be used alone or in combination. In order to obtain absorption over the entire visible light range, it is preferable to combine two or more dichroic dyes, and it is more preferable to combine three or more dichroic dyes. More preferred.

Examples of the azo dye include a compound represented by formula (I) (hereinafter, sometimes referred to as "compound (I)").
T ¹ -A ¹ (-N=NA ² ) _p -N=NA ³ -T ² (I)
[In formula (I), A ¹ , A ² , and A ³ each independently represent a 1,4-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, a benzoic acid phenyl ester group which may have a substituent, a 4,4'-stilbenylene group which may have a substituent, or a divalent heterocyclic group which may have a substituent, and T ¹ and T ² each represent an electron-withdrawing group or an electron-releasing group, and are located at a position substantially at 180° with respect to the azo bond plane. p represents an integer of 0 to 4. When p is 2 or more, each A ² may be the same or different from each other. Within the range in which absorption in the visible region is exhibited, the -N=N- bond may be replaced with a -C=C-, -COO-, -NHCO-, or -N=CH- bond.]

The content of the dichroic dye (the total amount when multiple types are included) is usually 1 to 60 parts by mass, preferably 1 to 40 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound, from the viewpoint of obtaining good light absorption characteristics. 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 the content is more than this range, the alignment of the liquid crystal molecules may be hindered.

<Frontmost layer>
The linear polarizing plate 10 may have an antireflection layer on the front surface. The antireflection layer has a function of preventing reflected light of external light from being visible on the surface of the linear polarizing plate 10, and can be formed by a conventional method for forming an antireflection layer, i.e., a coating method, a sputtering method, a vacuum deposition method, or the like. The antireflection layer may be formed in advance on the front side of a protective film provided on the front side of the linear polarizing plate 10, and the linear polarizing plate with an antireflection layer may be constituted using such a protective film, or may be provided separately from the protective film.

The linear polarizing plate 10 may have a surface treatment layer other than the anti-reflection layer on the front surface. Examples of such surface treatment layers include a hard coat layer, an anti-sticking layer, an anti-glare layer, a diffusion layer, etc.

[Retardation Plate]
The retardation plate 30 has a first liquid crystal retardation film 31 and a second liquid crystal retardation film 32, and the first liquid crystal retardation film 31 and the second liquid crystal retardation film 32 contain a cured product of a liquid crystal compound. The retardation plate 30 may have a third liquid crystal retardation film. The first liquid crystal retardation film, the second liquid crystal retardation film, and the third liquid crystal retardation film may each be composed of two or more layers. Hereinafter, an explanation that applies to any of the first liquid crystal retardation film 31, the second liquid crystal retardation film 32, and the third liquid crystal retardation film may be simply referred to as a "liquid crystal retardation film".

<Liquid crystal phase difference film>
In this specification, the optical axis of the polymerizable liquid crystal is defined as being aligned horizontally to the substrate plane as horizontal alignment, and the optical axis of the polymerizable liquid crystal is defined as being aligned perpendicularly to the substrate plane as vertical alignment. The optical axis refers to the direction in which a cross section cut in a direction perpendicular to the optical axis of an index ellipsoid formed by the orientation of the polymerizable liquid crystal is a circle, that is, the direction in which the refractive indexes in the three directions are all equal.

Polymerizable liquid crystals include rod-shaped polymerizable liquid crystals and disk-shaped polymerizable liquid crystals. When rod-shaped polymerizable liquid crystals are aligned horizontally or vertically to the substrate, the optical axis of the polymerizable liquid crystal coincides with the long axis direction of the polymerizable liquid crystal. When disk-shaped polymerizable liquid crystals are aligned, the optical axis of the polymerizable liquid crystal exists in a direction perpendicular to the disk surface of the polymerizable liquid crystal.

In order for the layer formed by polymerizing the polymerizable liquid crystal to exhibit in-plane retardation, the polymerizable liquid crystal may be aligned in an appropriate direction. When the polymerizable liquid crystal is rod-shaped, the optical axis of the polymerizable liquid crystal is aligned horizontally to the substrate plane to exhibit in-plane retardation. In this case, the optical axis direction and the slow axis direction are the same. When the polymerizable liquid crystal is disc-shaped, the optical axis of the polymerizable liquid crystal is aligned horizontally to the substrate plane to exhibit in-plane retardation. In this case, the optical axis and the slow axis are perpendicular to each other. The alignment state of the polymerizable liquid crystal can be adjusted by combining an alignment film with the polymerizable liquid crystal.

The in-plane retardation value of the liquid crystal retardation film can be adjusted by the thickness of the retardation film. Since the in-plane retardation value is determined by the formula (4), the desired in-plane retardation value (Re(λ)) can be obtained by adjusting Δn(λ) and the film thickness d.
Re(λ)=d×Δn(λ) (4)
In the formula, Re(λ) represents the in-plane retardation value at a wavelength of λ nm, d represents the film thickness, and Δn(λ) represents the birefringence at a wavelength of λ nm.

The birefringence Δn(λ) is obtained by measuring the in-plane retardation value and dividing it by the thickness of the retardation film. In a specific measurement method, the actual characteristics of the retardation film can be measured by measuring a film formed on a substrate that does not have an in-plane retardation in the substrate itself, such as a glass substrate.

When the optical axis of the rod-shaped polymerizable liquid crystal is aligned horizontally to the substrate plane, the refractive index relationship of the resulting retardation film is nx>ny≧nz (positive A plate), and the axis of the nx direction in the refractive index ellipsoid coincides with the slow axis.

In addition, when the optical axis of the disc-shaped polymerizable liquid crystal is oriented horizontally to the substrate plane, the refractive index relationship of the resulting retardation film is nx<ny≦nz (negative A plate), and the axis of the refractive index ellipsoid in the ny direction coincides with the slow axis.

In order for a layer formed by polymerizing a polymerizable liquid crystal to exhibit retardation in the thickness direction, the polymerizable liquid crystal may be oriented in an appropriate direction. In this specification, the expression of retardation in the thickness direction is defined as a property in which Rth (retardation value in the thickness direction) is negative in formula ( ₂₀ ). Rth can be calculated from the retardation value (R40) measured by tilting the in-plane fast axis at 40 degrees as the tilt axis, and the in-plane retardation value (Re). That is,
Rth can be calculated by determining nx, ny, and nz from Re, _R40 , d (the thickness of the retardation film), and n0 (the average refractive index of the retardation film) using the following formulas (21) to (23) and substituting these into formula (20).
Rth=[(nx+ny)/2-nz]×d (20)
Re = (nx-ny)×d (21)
R ₄₀ = (nx-ny') x d/cos(φ) (22)
(nx+ny+nz)/3=n0 (23)
Where:
φ=sin ^-1 [sin (40°)/n0]
ny'=ny×nz/[ny ² ×sin ² (φ)+nz ² ×cos ² (φ)] ^1/2
Additionally, nx, ny and nz are defined as above.

When the polymerizable liquid crystal is rod-shaped, the optical axis of the polymerizable liquid crystal is oriented perpendicular to the substrate plane to produce a phase difference in the thickness direction. When the polymerizable liquid crystal is disc-shaped, the optical axis of the polymerizable liquid crystal is oriented horizontally to the substrate plane to produce a phase difference in the thickness direction. In the case of disc-shaped polymerizable liquid crystal, the optical axis of the polymerizable liquid crystal is parallel to the substrate plane, so when Re is determined, the thickness is fixed and Rth is uniquely determined, but in the case of rod-shaped polymerizable liquid crystal, the optical axis of the polymerizable liquid crystal is perpendicular to the substrate plane, so Rth can be adjusted by adjusting the thickness of the retardation film without changing Re.

<Polymerizable Liquid Crystal>
The polymerizable liquid crystal is a compound having a polymerizable group and liquid crystallinity. The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group that can be involved in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystallinity of the polymerizable liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and when the thermotropic liquid crystal is classified according to the degree of order, it may be a nematic liquid crystal or a smectic liquid crystal.

Examples of rod-shaped polymerizable liquid crystals include compounds represented by the following formula (A) and compounds containing a group represented by the following formula (X). As rod-shaped polymerizable liquid crystals, liquid crystals having a T-shaped or H-shaped mesogen structure that is oriented perpendicular to the molecular axis direction and has birefringence are preferred from the viewpoint of wavelength dispersion expression, and T-shaped liquid crystals are more preferred from the viewpoint of obtaining stronger dispersion. Specific examples of the structure of T-shaped liquid crystals include compounds represented by the following formula (A).

(Compound represented by formula (A))
Formula (A) is as follows: Hereinafter, the compound represented by formula (A) may be referred to as polymerizable liquid crystal (A).

In formula (A), Ar represents a divalent aromatic group which may have a substituent. The divalent aromatic group preferably contains at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. When the divalent group Ar contains two or more aromatic groups, the two or more aromatic groups may be bonded to each other via a divalent bonding group such as a single bond, -CO-O-, or -O-.
G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be 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, and a carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom.
L ¹ , L ² _, B ¹ and B ² each independently represent a single bond or a divalent linking group.
k and l each independently represent an integer of 0 to 3, and satisfy the relationship 1≦k+l, where, when 2≦k+l, B ¹ and B ² , G ¹ and G ² may be the same as or different from each other.
^E1 and ^E2 each independently represent an alkanediyl group having 1 to 17 carbon atoms, in which a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and _-CH2- contained in the alkanediyl group may be substituted with -O-, -S- or -COO-, and when there are a plurality of -O-, -S- or -COO-, they are not adjacent to each other. ^P1 and ^P2 each independently represent a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

G ¹ and G ² are each independently preferably a 1,4-phenylenediyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, or a 1,4-cyclohexanediyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably a 1,4-phenylenediyl group substituted with a methyl group, an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group.
At least one of a plurality of ^G1 and ^G2 is preferably a divalent alicyclic hydrocarbon group, and more preferably at least one of ^G1 and ^G2 bonded to ^L1 or ^L2 is a divalent alicyclic hydrocarbon group.

^L1 and ^L2 each independently represent preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a1 OR ^a2 -, -R ^a3 COOR ^a4 -, -R ^a5 OCOR ^a6 -, R ^a7 OC=OOR ^a8 -, -N=N-, -CR ^c =CR ^d -, or C≡C-, where R ^a1 to R ^a8 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently more preferably a single bond, -OR ^a2-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 -, or OCOR ^a6-1 -. Here, R ^a2-1 , R ^a4-1 , and R ^a6-1 each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. L ¹ and L ² are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, or OCO-.

B ¹ and B ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -, -R ^a11 COOR ^a12 -, -R ^a13 OCOR ^a14 -, or -R ^a15 OC(═O)OR ^a16 -. Here, R ^a9 to R ^a16 are each independently a single bond, or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently more preferably a single bond, -OR ^a10-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 -, or OCOR ^a14-1 -. Here, R ^a10-1 , R ^a12-1 and R ^a14-1 each independently represent a single bond, -CH ₂ - or -CH ₂ CH ₂ -. B ¹ and B ² each independently represent more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, -OCO- or -OCOCH ₂ CH ₂ -.

From the viewpoint of expressing reverse wavelength dispersion, k and l are preferably in the range of 2≦k+l≦6, preferably k+l=4, and more preferably k=2 and l=2. k=2 and l=2 are preferable because they result in a symmetrical structure.

E ¹ and E ² each independently preferably represent an alkanediyl group having 1 to 17 carbon atoms, and more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of the polymerizable group represented by ^P1 or ^P2 include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

It is preferable that Ar has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferable. Examples of the aromatic heterocycle include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among them, it is preferable that Ar has a thiazole ring, a benzothiazole ring, or a benzofuran ring, and it is more preferable that Ar has a benzothiazole group. In addition, when Ar contains a nitrogen atom, it is preferable that the nitrogen atom has π electrons.

In formula (A), the total number Nπ of π electrons contained in the divalent aromatic group represented by _Ar is preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. Also, it is preferably 30 or less, more preferably 26 or less, and even more preferably 24 or less.

Suitable examples of aromatic groups represented by Ar include the following groups:

In formulae (Ar-1) to (Ar-23), the mark * represents a linking portion, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or an N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

Q ¹ , Q ² and Q ³ each independently represent -CR ^2' R ^3' -, -S-, -NH-, -NR ^2' -, -CO- or O-, and R ^2' and R ^3' each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

Y ¹ , Y ² and Y ³ each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may be substituted.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group, or a halogen atom; m represents an integer of 0 to 6.

Examples of the aromatic hydrocarbon group in ^Y1 , ^Y2 , and ^Y3 include aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, of which a phenyl group and a naphthyl group are preferred, and a phenyl group is more preferred. Examples of the aromatic heterocyclic group include aromatic heterocyclic groups having 4 to 20 carbon atoms and containing at least one heteroatom, such as a nitrogen atom, an oxygen atom, or a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group, of which a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group are preferred.

^Y1 , ^Y2 and ^Y3 may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Z ⁰ , Z ¹ and Z ² are each preferably independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms, Z ⁰ is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group.

Q ¹ , Q ² and Q ³ are preferably -NH-, -S-, -NR ^2' - or -O-, and R ^2' is preferably a hydrogen atom, with -S-, -O- and -NH- being particularly preferred.

Among the formulae (Ar-1) to (Ar-23), the formulae (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.
In formulae (Ar-16) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ^0. Examples of the aromatic heterocyclic group include those described above as aromatic heterocyclic rings that Ar may have, such as a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. This aromatic heterocyclic group may have a substituent. In addition, Y ¹ may be, together with the nitrogen atom to which it is bonded and Z ⁰ , the aforementioned polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group which may be substituted. Examples include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring.

(Compound containing a group represented by formula (X))
Formula (X) is as follows: Hereinafter, a compound containing a group represented by formula (X) may be referred to as polymerizable liquid crystal (B).
P11-B11-E11-B12-A11-B13- (X)

In formula (X), P11 represents a polymerizable group.
A11 represents a divalent alicyclic hydrocarbon group or a divalent aromatic hydrocarbon group. A hydrogen atom contained in the divalent alicyclic hydrocarbon group and the divalent aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, or a nitro group, and a hydrogen atom contained in the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms may be substituted with a fluorine atom.
B11 represents -O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -CO-NR ¹⁶ -, -NR ¹⁶ -CO-, -CO-, -CS- or a single bond, and R ¹⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
B12 and B13 each independently represent -C≡C-, -CH=CH-, -CH ₂ -CH ₂ -, -O-, -S-, -C(=O)-, -C(=O)-O-, -O-C(=O)-O-, -CH=N-, -N=CH-, -N=N-, -C(=O)-NR ¹⁶ -, -NR ¹⁶ -C(=O)-, -OCH ₂ -, _-OCF 2 -, -CH ₂ O-, -CF ₂ O-, -CH=CH-C(=O)-O-, -O-C(=O)-CH=CH- or a single bond.
E11 represents an alkanediyl group having 1 to 12 carbon atoms, a hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. In addition, -CH ₂ - constituting the alkanediyl group may be replaced with -O- or -CO-.]

The number of carbon atoms in the aromatic hydrocarbon group and alicyclic hydrocarbon group of A11 is preferably in the range of 3 to 18, more preferably in the range of 5 to 12, and particularly preferably 5 or 6. A11 is preferably a cyclohexane-1,4-diyl group or a 1,4-phenylene group.

E11 is preferably a linear alkanediyl group having 1 to 12 carbon atoms. --CH ₂ -- constituting the alkanediyl group may be replaced with --O--.
Specific examples of such alkyl groups include linear alkanediyl groups having 1 to 12 carbon atoms, such as a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane- _1,9 -diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, and a dodecane-1,12-diyl group; -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -, -CH 2 -CH ₂ -O-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ - and -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -O-CH ₂ Examples include —CH ₂ —.
As B11, --O--, --S--, --CO--O--, and --O--CO-- are preferable, and among them, --CO--O-- is more preferable.
As B12 and B13, each independently is preferably -O-, -S-, -C(=O)-, -C(=O)-O-, -O-C(=O)- or -O-C(=O)-O-, and among these, -O- or -O-C(=O)-O- is more preferable.

As the polymerizable group represented by P11, a radically polymerizable group or a cationic polymerizable group is preferred because of its high polymerization reactivity, particularly photopolymerization reactivity. In addition, the polymerizable group is preferably a group represented by the following formulae (P-11) to (P-15), because it is easy to handle and the liquid crystal compound itself is easy to manufacture.

[In formulas (P-11) to (P-15),
R ¹⁷ to R ²¹ each independently represent an alkyl group having 1 to 6 carbon atoms or a hydrogen atom.]

Specific examples of the groups represented by formulas (P-11) to (P-15) include the groups represented by the following formulas (P-16) to (P-20).

P11 is preferably a group represented by formula (P-14) to formula (P-20), and more preferably a vinyl group, a p-stilbene group, an epoxy group or an oxetanyl group.
The group represented by P11-B11- is more preferably an acryloyloxy group or a methacryloyloxy group.

The polymerizable liquid crystal (B) may be a compound represented by formula (I), formula (II), formula (III), formula (IV), formula (V) or formula (VI).
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-B16-E12-B17-P12 (I)
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-F11 (II)
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-E12-B17-P12 (III)
P11-B11-E11-B12-A11-B13-A12-B14-A13-F11 (IV)
P11-B11-E11-B12-A11-B13-A12-B14-E12-B17-P12 (V)
P11-B11-E11-B12-A11-B13-A12-F11 (VI)
(Wherein,
A12 to A14 each independently have the same meaning as A11, B14 to B16 each independently have the same meaning as B12, B17 has the same meaning as B11, and E12 has the same meaning as E11.
F11 represents a hydrogen atom, an alkyl group having 1 to 13 carbon atoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, a nitro group, a trifluoromethyl group, a dimethylamino group, a hydroxy group, a methylol group, a formyl group, a sulfo group ( _-SO3H ), a carboxy group, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom, and _-CH2- constituting the alkyl group and the alkoxy group may be replaced by -O-.

Specific examples of polymerizable liquid crystals (B) include compounds having a polymerizable group among those described in "3.8.6 Network (fully cross-linked type)" and "6.5.1 Liquid crystal materials b. Polymerizable nematic liquid crystal materials" in Liquid Crystal Handbook (edited by Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2000), and the polymerizable liquid crystals described in JP-A Nos. 2010-31223, 2010-270108, 2011-6360, and 2011-207765.

Specific examples of the polymerizable liquid crystal (B) include compounds represented by the following formulas (I-1) to (I-4), (II-1) to (II-4), (III-1) to (III-26), (IV-1) to (IV-26), (V-1) to (V-2), and (VI-1) to (VI-6). In the following formulas, k1 and k2 each independently represent an integer from 2 to 12. These polymerizable liquid crystals (B) are preferred in terms of ease of synthesis or availability.

An example of a disc-shaped polymerizable liquid crystal is a compound containing a group represented by formula (W) (hereinafter sometimes referred to as polymerizable liquid crystal (C)).

［式（Ｗ）中、Ｒ^４０は、下記式（Ｗ－１）～（Ｗ－５）を表わす。

In formula (W), R ⁴⁰ represents any one of the following formulae (W-1) to (W-5).

X ⁴⁰ and Z ⁴⁰ each represent an alkyl group having 1 to 12 carbon atoms, a hydrogen atom contained in the alkyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. In addition, -CH ₂ - constituting the alkyl group may be replaced with -O- or -CO-.

Specific examples of the polymerizable liquid crystal (C) include the compounds described in "6.5.1 Liquid crystal material b. Polymerizable nematic liquid crystal material FIG. 6.21" in Liquid Crystal Handbook (edited by Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2000), and the polymerizable liquid crystals described in JP-A-7-258170, JP-A-7-30637, JP-A-7-309807, and JP-A-8-231470.

The retardation plate 30 having the optical properties represented by formulas (11) and (12) can be obtained by combining layers having the optical properties represented by formulas (14), (16), and (17) with layers having the optical properties represented by formulas (15), (16), and (17) in a specific slow axis relationship.
Re(450)/Re(550)≦1.00 (11)
1.00≦Re(650)/Re(550) (12)
100nm<Re(550)<150nm (14)
150nm<Re(550)<320nm (15)
Re(450)/Re(550)≧1.00 (16)
1.00≧Re(650)/Re(550) (17)

The retardation plate 30 preferably has the optical characteristics expressed by formulas (11) and (12). When the retardation plate 30 has the optical characteristics expressed by formulas (11) and (12), uniform polarization conversion characteristics can be obtained for light of each wavelength in the visible light range, and coloring of reflected light when displaying black on a display device such as an organic EL display device can be suppressed.

The polymerizable liquid crystal having the specific structure may be, for example, the polymerizable liquid crystal (A). By orienting the polymerizable liquid crystal (A) so that the optical axis is horizontal to the substrate plane, a retardation film having the optical properties represented by formula (11) and formula (12) can be obtained, and by adjusting the film thickness, a retardation film having a desired in-plane retardation value such as the optical property represented by formula (14) can be obtained.
100nm<Re(550)<150nm (14)

A method of combining a layer having optical properties represented by formulas (14), (16), and (17) with a layer having optical properties represented by formulas (15), (16), and (17) in a specific slow axis relationship includes well-known methods. For example, JP-A-2001-4837, JP-A-2001-21720, and JP-A-2000-206331 disclose a retardation film having at least two retardation films made of liquid crystal compounds. The layer having optical properties represented by formula (14) is also called a 1/4 wavelength layer, the layer having optical properties represented by formula (15) is also called a 1/2 wavelength layer, and the optical properties represented by formulas (16) and (17) are also called positive wavelength dispersion. Furthermore, from the viewpoint of being able to compensate for the anti-reflection function in an oblique direction, it is preferable to further include a layer having anisotropy in the thickness direction (positive C plate). Furthermore, each optically anisotropic layer may have a tilt alignment or may form a cholesteric alignment state.

A retardation film having the optical characteristics expressed by the above formulas (16) and (17) can be obtained by a known method. In other words, a retardation film obtained by a method other than the method for obtaining a retardation film having the optical characteristics expressed by the above formulas (11) and (12) generally has the optical characteristics expressed by the above formulas (16) and (17).

In a preferred embodiment of the retardation plate 30, the first liquid crystal retardation film 31 has optical characteristics expressed by the formulas (15), (16), and (17), and the second liquid crystal retardation film 32 has optical characteristics expressed by the formulas (14), (16), and (17).
100nm<Re(550)<150nm (14)
150nm<Re(550)<320nm (15)
Re(450)/Re(550)≧1.00 (16)
1.00≧Re(650)/Re(550) (17)
The second liquid crystal retardation film 32 is preferably a layer having the optical characteristic expressed by formula (14-1), and the first liquid crystal retardation film 31 is preferably a layer having the optical characteristic expressed by formula (15-1).
130nm<Re(550)<150nm (14-1)
265nm<Re(550)<285nm (15-1)

The first liquid crystal retardation film 31 is preferably a coating layer formed by polymerizing a polymerizable liquid crystal (C). The second liquid crystal retardation film 32 is preferably a coating layer formed by polymerizing a polymerizable liquid crystal (B).

The first liquid crystal phase difference film 31 and the second liquid crystal phase difference film 32 each preferably have a thickness of 0.2 μm or more and 3.0 μm or less, and more preferably 0.4 μm or more and 2.8 μm or less. According to the present invention, even if the thickness of the first liquid crystal phase difference film 31 and the second liquid crystal phase difference film 32 is 3.0 μm or less, it is possible to reduce interference unevenness visible from an oblique direction.

The thickness of the liquid crystal retardation film can be determined by measurement using an interference thickness gauge, a laser microscope, or a stylus thickness gauge.

The first liquid crystal retardation film 31 and the second liquid crystal retardation film 32 are preferably arranged so that they intersect in-plane at an intersecting angle of, for example, 50° to 70°. The intersecting angle here means the narrowest intersecting angle between the two slow axes.

With respect to the absorption axis of the polarizer, the slow axis of the first liquid crystal retardation film 31 is, for example, 10° to 20°, preferably 12° to 18°, and more preferably about 15°, and the slow axis of the second liquid crystal retardation film 32 is, for example, 70° or more and 80° or less, more preferably 72° or more and 78° or less, and more preferably about 75°.
In another embodiment, the slow axis of the first liquid crystal retardation film 31 is, for example, −10° to −20°, preferably −12° to −18°, and more preferably about −15°, relative to the absorption axis of the polarizer, and the slow axis of the second liquid crystal retardation film 32 is, for example, −70° to −80°, more preferably −72° to −78°, and more preferably about −75°.
In still another embodiment, the slow axis of the first liquid crystal retardation film 31 is at an angle of 70° to 80°, preferably 72° to 78°, and more preferably about 75°, relative to the absorption axis of the polarizer, and the slow axis of the second liquid crystal retardation film 32 is at an angle of, for example, 10° to 20°, more preferably 12° to 18°, and more preferably about 15°.
In still another embodiment, the slow axis of the first liquid crystal retardation film 31 is −70° to −80°, preferably −72° to −78°, and more preferably about −75°, relative to the absorption axis of the polarizer, and the slow axis of the second liquid crystal retardation film 32 is, for example, −10° to −20°, more preferably −12° to −18°, and more preferably about −15°.

<Substrate>
The retardation plate 30 may have a substrate. The substrate is usually a transparent substrate. The transparent substrate means a substrate having transparency capable of transmitting light, particularly visible light, and transparency means a property in which the transmittance for light rays having a wavelength of 380 to 780 nm is 80% or more. Examples of the substrate include glass substrates and film substrates, and film substrates are preferred, with long rolled films being more preferred in terms of being continuously manufactured. Examples of resins constituting the film substrate include plastics such as polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide, and polyphenylene oxide. Among these, from the viewpoint of transparency when used in optical film applications, a film substrate selected from any one of triacetyl cellulose, cyclic olefin resins, polymethacrylic acid esters, and polyethylene terephthalate is more preferable.

Examples of commercially available cellulose ester substrates include "FUJITAC FILM" (manufactured by Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY" and "KC4UY" (all manufactured by Konica Minolta Opto, Inc.).
Examples of commercially available cyclic olefin resins include "Topas" (registered trademark) (manufactured by Ticona (Germany)), "Arton" (registered trademark) (manufactured by JSR Corporation), "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (all manufactured by Zeon Corporation), and "Apel" (registered trademark) (manufactured by Mitsui Chemicals, Inc.). Such cyclic olefin resins can be formed into a film by known means such as a solvent casting method or a melt extrusion method to form a substrate. Commercially available cyclic olefin resin substrates can also be used. Examples of commercially available cyclic olefin resin substrates include "S-Cina" (registered trademark), "SCA40" (registered trademark) (all manufactured by Sekisui Chemical Co., Ltd.), "ZEONOR Film" (registered trademark) (manufactured by Optes Co., Ltd.), and "Arton Film" (registered trademark) (manufactured by JSR Corporation).

The thickness of the substrate is preferably thin enough to allow practical handling, but if it is too thin, the strength decreases and workability tends to be poor. The thickness of the substrate is usually 5 μm to 300 μm, preferably 10 μm to 200 μm, and more preferably 10 to 50 μm. Furthermore, a further thinning effect can be obtained by peeling off the substrate and transferring a polarizing film or a retardation film.

<Alignment film>
In this specification, the alignment film has an alignment regulating force for aligning a polymerizable liquid crystal compound in a desired direction.

The alignment film facilitates the alignment of the polymerizable liquid crystal compound. The state of liquid crystal alignment, such as horizontal alignment, vertical alignment, hybrid alignment, and tilt alignment, varies depending on the properties of the alignment film and the polymerizable liquid crystal compound, and the combination can be selected arbitrarily. For example, if the alignment film is a material that exerts horizontal alignment as an alignment control force, the polymerizable liquid crystal compound can form a horizontal alignment or a hybrid alignment, and if the alignment film is a material that exerts vertical alignment, the polymerizable liquid crystal compound can form a vertical alignment or a tilt alignment. The expressions horizontal, vertical, and the like refer to the direction of the optical axis of the aligned polymerizable liquid crystal compound when the plane of the optical anisotropic layer is used as a reference. For example, vertical alignment means that the optical axis of the aligned polymerizable liquid crystal compound is in a direction perpendicular to the plane of the optical anisotropic layer. The term "vertical" here means 90°±20° relative to the plane of the optical anisotropic layer.

When the alignment film is made of an alignment polymer, the alignment control force can be adjusted as desired by changing the surface condition and rubbing conditions. When the alignment film is made of a photoalignment polymer, the alignment control force can be adjusted as desired by changing the polarized light irradiation conditions, etc. In addition, the liquid crystal alignment can also be controlled by selecting the physical properties of the polymerizable liquid crystal compound, such as the surface tension and liquid crystallinity.

The alignment film formed between the substrate and the liquid crystal retardation film is preferably insoluble in the solvent used to form the liquid crystal retardation film on the alignment film, and is heat resistant to the heat treatment for removing the solvent and for orienting the liquid crystal. Examples of the alignment film include an alignment film made of an orienting polymer, a photoalignment film, a groove alignment film, and a stretched film stretched in the alignment direction. When applied to a long rolled film, a photoalignment film is preferred because the alignment direction can be easily controlled.

The thickness of the alignment film is usually 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.

Examples of the alignment polymers used in the rubbed alignment film include polyamides and gelatins having amide bonds in the molecule, polyimides having imide bonds in the molecule, and their hydrolyzates such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. Among these, polyvinyl alcohol is preferred. These alignment polymers may be used alone or in combination of two or more.

One method of rubbing is to bring a film of oriented polymer formed on the surface of a substrate by applying an oriented polymer composition to the substrate and annealing the composition into contact with a rotating rubbing roll wrapped with a rubbing cloth.

The photo-alignment film is made of a polymer, oligomer, or monomer that has a photoreactive group. The photo-alignment film can obtain an alignment control force by irradiating it with polarized light. The photo-alignment film is more preferable in that the direction of the alignment control force can be freely controlled by selecting the polarization direction of the irradiated polarized light.

Photoreactive groups are groups that develop liquid crystal alignment ability when irradiated with light. Specifically, they are groups that develop photoreactions that are the origin of liquid crystal alignment ability, such as molecular alignment induction or isomerization reactions, dimerization reactions, photocrosslinking reactions, or photodecomposition reactions, which are induced by light irradiation. Among these photoreactive groups, those that undergo dimerization reactions or photocrosslinking reactions are preferred in terms of excellent alignment properties. As photoreactive groups that can develop the above-mentioned reactions, those having unsaturated bonds, particularly double bonds, are preferred, and groups having at least one selected from the group consisting of carbon-carbon double bonds (C=C bonds), carbon-nitrogen double bonds (C=N bonds), nitrogen-nitrogen double bonds (N=N bonds), and carbon-oxygen double bonds (C=O bonds) are more preferred.

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

The polarized light can be irradiated directly from the film surface or from the substrate side and then transmitted through the film. 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 the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) with a wavelength of 250 to 400 nm is particularly preferable. Examples of light sources used for the 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 ultraviolet light with a wavelength of 313 nm with a high emission intensity. The light from the light source can be irradiated through an appropriate polarizer to irradiate the polarized light. Examples of such polarizers include polarizing filters, polarizing prisms such as Glan-Thompson and Glan-Taylor, and wire grid type polarizers.

<Composition for forming polarizing film, composition for forming liquid crystal retardation film>
The composition for forming a polarizing film or the composition for forming a liquid crystal retardation film (hereinafter also referred to as the composition for forming an optically anisotropic layer) may further contain a solvent, a leveling agent, a polymerization initiator, a photosensitizer, a polymerization inhibitor, The composition may contain reactive additives such as a crosslinking agent and an adhesion agent, and preferably contains a solvent and a leveling agent from the viewpoint of processability.

(solvent)
The composition for forming an optically anisotropic layer may contain a solvent. Since the polymerizable liquid crystal compound generally has a high viscosity, the composition for forming an optically anisotropic layer is easily applied by dissolving the compound in a solvent, and as a result, the optically anisotropic layer is often easily formed. As the solvent, a solvent that can completely dissolve the polymerizable liquid crystal compound is preferable, and a solvent that is inactive to the polymerization reaction of the polymerizable liquid crystal compound is preferable.

Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone or 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; aromatic hydrocarbon solvents such as toluene and xylene, and nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; and amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 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 relative to the total amount of the composition for forming an optically anisotropic layer. In other words, the content of the solid content in the composition for forming an optically anisotropic layer is preferably 2 to 50% by mass, more preferably 5 to 30% by mass. If the content of the solid content is 50% by mass or less, the viscosity of the composition for forming an optically anisotropic layer is low, and the thickness of the optically anisotropic layer becomes approximately uniform, so that interference unevenness tends to be less likely to occur in the optically anisotropic layer. In addition, the content of the solid content can be determined in consideration of the thickness of the optically anisotropic layer to be produced.

(Leveling Agent)
The optically anisotropic layer forming composition may contain a leveling agent.The leveling agent is an additive that adjusts the fluidity of the composition and makes the film obtained by applying the composition flatter, and for example, includes organic modified silicone-based, polyacrylate-based and perfluoroalkyl-based leveling agents.Among them, when horizontal alignment is performed, polyacrylate-based and perfluoroalkyl-based leveling agents are preferred, and when vertical alignment is performed, organic modified silicone-based and perfluoroalkyl-based leveling agents are preferred.

When the composition for forming an optically anisotropic layer contains a leveling agent, the amount is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the amount of the leveling agent is within the above range, the polymerizable liquid crystal compound is easily aligned horizontally, and the optically anisotropic layer obtained tends to be smoother. When the amount of the leveling agent relative to the polymerizable liquid crystal compound exceeds the above range, interference unevenness tends to occur in the optically anisotropic layer obtained. The composition for forming an optically anisotropic layer may contain two or more types of leveling agents.

(Polymerization initiator)
The composition for forming an optically anisotropic layer may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating a polymerization reaction of a polymerizable liquid crystal compound or 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.

The photopolymerization initiator may be any known photopolymerization initiator, so long as it is a compound capable of initiating the polymerization reaction of the polymerizable liquid crystal compound. Specific examples include photopolymerization initiators capable of generating active radicals or acids under the action of light, and among these, photopolymerization initiators that generate radicals under the action of light are preferred. Photopolymerization initiators may be used alone or in combination of two or more types.

As the photopolymerization initiator, a known photopolymerization initiator can be used. For example, as a photopolymerization initiator that generates active radicals, self-cleavage type benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, azo compounds, etc. can be used, and hydrogen abstraction type benzophenone compounds, alkylphenone compounds, benzoin ether compounds, benzyl ketal compounds, dibenzosuberone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, triazine compounds, etc. can be used. As a photopolymerization initiator that generates acid, iodonium salts and sulfonium salts can be used. From the viewpoint of excellent reaction efficiency at low temperatures, self-cleavage type photopolymerization initiators are preferred, and acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are particularly preferred.

The content of the polymerization initiator in the composition for forming the optically anisotropic layer can be adjusted as appropriate depending on the type and amount of the polymerizable liquid crystal compound, but is usually 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 8 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerization initiator is within the above range, polymerization can be carried out without disturbing the alignment of the polymerizable liquid crystal compound.

(Sensitizer)
The composition for forming an optically anisotropic layer may contain a sensitizer. The sensitizer is preferably a photosensitizer. Examples of the sensitizer include xanthone compounds such as xanthone and thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and alkoxy group-containing anthracene (e.g., dibutoxyanthracene, etc.); phenothiazine, rubrene, etc.

When the composition for forming an optically anisotropic layer contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the composition for forming an optically anisotropic layer can be further promoted. The amount of such a sensitizer used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

(Antioxidants)
In order to stably proceed with the polymerization reaction, the composition for forming the optically anisotropic layer may contain an antioxidant, which can control the degree of progress of the polymerization reaction of the polymerizable liquid crystal compound.

The antioxidant may be, for example, a primary antioxidant selected from a phenol-based antioxidant, an amine-based antioxidant, a quinone-based antioxidant, or a nitroso-based antioxidant, or a secondary antioxidant selected from a phosphorus-based antioxidant and a sulfur-based antioxidant.

When the composition for forming an optically anisotropic layer contains an antioxidant, the content of the antioxidant is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. The antioxidants can be used alone or in combination of two or more kinds. When the content of the antioxidant is within the above range, polymerization can be carried out without disturbing the alignment of the polymerizable liquid crystal compound.

<Composition for forming optically anisotropic layer; reactive additive>
The composition for forming an optically anisotropic layer may contain a reactive additive. The reactive additive preferably has a carbon-carbon unsaturated bond, an active hydrogen reactive group, or a thiol group in its molecule. The term "active hydrogen reactive group" as used herein means a group reactive to a group having active hydrogen such as a carboxyl group (-COOH), a hydroxyl group (-OH), or an amino group (-NH ₂ ), and 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 reactive groups possessed by the reactive additive is usually 1 to 20, and preferably 1 to 10, for each.

<Polarizing film, liquid crystal retardation film>
(Protective Layer)
The polarizing film or liquid crystal retardation film (hereinafter also referred to as an optically anisotropic layer) may further have a protective layer. The optically anisotropic layer is laminated on another film by adhesion with a pressure-sensitive adhesive or the like. In such a case, the presence of a protective layer can prevent low molecular weight components such as unreacted polymerizable liquid crystal compounds and dichroic dyes in the optically anisotropic layer from diffusing into other layers.

It is preferable that the protective layer is thin so that it can prevent low molecular weight components such as unreacted polymerizable liquid crystal compounds and dichroic dyes in the optically anisotropic layer from diffusing into other layers. The preferred film thickness is 0.1 μm to 10 μm, more preferably 0.1 μm to 5 μm, and even more preferably 0.1 μm to 3 μm.

The protective layer is preferably a polymer with a high crosslink density or a water-soluble polymer with high hydrophilic interaction. For example, it contains at least one selected from the group consisting of acrylic resin, epoxy resin, oxetane resin, urethane resin, melamine resin, and polyvinyl alcohol resin. Among these, from the viewpoint of high curability and ease of formation, it is preferable to contain at least one selected from the group consisting of acrylic resin, epoxy resin, oxetane resin, urethane resin, and melamine resin, and it is more preferable to contain at least one selected from the group consisting of acrylic resin and urethane resin. Also, from the viewpoint of hydrophilicity, polyvinyl alcohol resin is preferable.

<Method of manufacturing optically anisotropic layer>
The optically anisotropic layer can be produced by applying a composition for forming an optically anisotropic layer onto a substrate and an alignment film.

<Coating of composition for forming optically anisotropic layer>
Examples of the method for applying the composition for forming an optically anisotropic layer on a substrate or an alignment film include an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a CAP coating method, a slit coating method, a microgravure method, a die coating method, and an inkjet method. Examples of the method for applying the composition using a coater such as a dip coater, a bar coater, or a spin coater are also included. Among these, when applying continuously in a roll-to-roll format, the application method using the microgravure method, the inkjet method, the slit coating method, or the die coating method is preferred, and when applying to a sheet substrate such as glass, the spin coating method, which has high uniformity, is preferred. When applying in a roll-to-roll format, the composition for forming an alignment film is applied to the substrate to form an alignment film, and the composition for forming an optically anisotropic layer can be continuously applied on the obtained alignment film.

<Drying of the composition for forming an optically anisotropic layer>
Examples of drying methods for removing the solvent contained in the composition for forming an optically anisotropic layer include natural drying, ventilation drying, heat drying, reduced pressure drying, and combinations of these. Of 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, and even more preferably in the range of 50 to 130°C. The drying time is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes. The composition for forming a photo-alignment film and the alignable polymer composition can also be dried in the same manner.

<Polymerization of polymerizable liquid crystal compound>
Photopolymerization is preferred as a method for polymerizing the polymerizable liquid crystal compound. Photopolymerization is performed by irradiating an active energy ray to a laminate in which an optically anisotropic layer-forming composition containing a polymerizable liquid crystal compound is applied on a substrate or an alignment film. The active energy ray to be irradiated is appropriately selected according to the type of polymerizable liquid crystal compound contained in the dried coating (particularly, the type of photopolymerizable functional group possessed by the polymerizable liquid crystal compound), the type of photopolymerization initiator when a photopolymerization initiator is contained, and the amount thereof. 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 them, ultraviolet light is preferred in that the progress of the polymerization reaction is easily controlled and that photopolymerization devices widely used in this field can be used, and it is preferable to select the type of polymerizable liquid crystal compound so that it can be photopolymerized by ultraviolet light.

Examples of light sources for the active energy rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium interferometer lamps, excimer lasers, LED light sources emitting light in the wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

The ultraviolet irradiation intensity is usually 10 mW/cm ² to 3,000 mW/cm ^2. The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a cationic polymerization initiator or a radical polymerization initiator. The time for irradiating light is usually 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. When irradiating once or a plurality of times with such ultraviolet irradiation intensity, the accumulated light amount is 10 mJ/cm ² to 3,000 mJ/cm ² , preferably 50 mJ/cm ² to 2,000 mJ/cm ² , and more preferably 100 mJ/cm ² to 1,000 mJ/cm ^2. When the accumulated light amount is less than this range, the polymerizable liquid crystal compound may not be sufficiently cured, and good transferability may not be obtained. Conversely, when the accumulated light amount is more than this range, the optical film including the optically anisotropic layer may be colored.

[Method of manufacturing phase difference plate]
In the method for producing the retardation plate, the order in which the first liquid crystal retardation film and the second liquid crystal retardation film are formed is arbitrary.

Figure 2 is a schematic cross-sectional view showing a specific example of the retardation plate 30. Figure 2(a) is a retardation plate 30 in which a first liquid crystal retardation film 31 and a second liquid crystal retardation film 32 are laminated. Figure 2(b) is a retardation plate 30 in which a base material 33, a first liquid crystal retardation film 31, and a second liquid crystal retardation film 32 are laminated in this order. Figure 2(c) is a retardation plate 30 in which a base material 33, a second liquid crystal retardation film 32, and a first liquid crystal retardation film 31 are laminated in this order. Figure 2(d) is a retardation plate 30 in which a first liquid crystal retardation film 31, a base material 33, and a second liquid crystal retardation film 32 are laminated in this order.

By removing the substrate 33 from the retardation film 30, a retardation film 30 without a substrate (Figure 2(a)) can be obtained.

The retardation plate 30 can also be manufactured by bonding a substrate 33 having a first liquid crystal retardation film 31 and a substrate 33' having a second liquid crystal retardation film 32 together. Specific examples are shown in Figures 2(e), 2(f) and 2(g). A second adhesive layer 34 is used for bonding. The second adhesive layer 34 is not shown in Figures 2(a) to 2(g).

[Method of manufacturing optical laminate]
The optical laminate of this embodiment can be obtained by bonding the retardation plate and the linear polarizer using the first adhesive layer. The method of bonding a retardation plate without a substrate to a linear polarizer includes a method of bonding a retardation plate from which the substrate has been removed to a linear polarizer using the first adhesive layer, and a method of bonding a retardation plate to a linear polarizer using the first adhesive layer and then removing the substrate. In this case, the first adhesive layer may be directly formed by applying an adhesive to the retardation film side of the retardation plate, or may be directly formed by applying an adhesive to the linear polarizer side, or a first adhesive layer formed on another substrate in advance may be interposed between the linear polarizer and the retardation plate. If there is an alignment film between the substrate and the retardation film, the alignment film may be removed together with the substrate.

Substrates having functional groups on their surface that form chemical bonds with retardation films or alignment films tend to form chemical bonds with the retardation films or alignment films, making them difficult to remove. Therefore, when removing the substrate by peeling, substrates with fewer functional groups on the surface are preferred, and substrates that have not been subjected to a surface treatment that forms functional groups on the surface are preferred.

Also, since an alignment film having functional groups that form chemical bonds with a substrate tends to have a strong adhesive force between the substrate and the alignment film, when the substrate is to be removed by peeling, an alignment film having fewer functional groups that form chemical bonds with the substrate is preferred. Also, it is preferable that the alignment film does not contain a reagent that crosslinks the substrate and the alignment film, and further, it is preferable that the solution of the alignment polymer composition and the photoalignment film forming composition does not contain a component such as a solvent that dissolves the substrate.

Also, an alignment film having a functional group that forms a chemical bond with the retardation film tends to have a strong adhesive force between the retardation film and the alignment film. Therefore, when the alignment film is to be removed together with the substrate, an alignment film having a small number of functional groups that form a chemical bond with the retardation film is preferred. Also, it is preferable that the retardation film and the alignment film do not contain a reagent that crosslinks the retardation film and the alignment film.

In addition, a retardation film having a functional group that forms a chemical bond with the alignment film tends to have a strong adhesive force between the alignment film and the retardation film. Therefore, when removing the substrate or removing the alignment film together with the substrate, a retardation film having a small number of functional groups that form a chemical bond with the substrate or alignment film is preferred. In addition, the polymerizable liquid crystal composition preferably does not contain a reagent that crosslinks the substrate or alignment film with the retardation film.

For example, a first adhesive layer 21 can be attached to the surface of the first liquid crystal phase difference film 31 of a phase difference plate 30 in which a substrate, a second liquid crystal phase difference film 32, a second adhesive layer 34, and a first liquid crystal phase difference film 31 are laminated in this order, a linear polarizer 10 is laminated thereto, and then the substrate of the phase difference plate 30 can be removed to produce an optical laminate having the configuration shown in Figure 1 in which a linear polarizer 10, a first adhesive layer 21, a first liquid crystal phase difference film 31, a second adhesive layer 34, and a second liquid crystal phase difference film 32 are laminated in this order. In addition, a polarizing plate in which a linear polarizing plate, a second liquid crystal retardation film, a first adhesive layer, and a second liquid crystal retardation film are laminated in this order can be manufactured by attaching a second adhesive layer to the surface of the second liquid crystal retardation film of a retardation plate in which a substrate, a first adhesive layer, and a second liquid crystal retardation film are laminated in this order, and then laminating a linear polarizing plate thereon, and then removing the substrate of the retardation plate. From the viewpoint of thinning, it is preferable to peel off the substrate.

The method for polishing the end faces of the optical laminate includes, for example, the following steps.
[a] a first step of stacking a plurality of optical laminates to obtain a laminate; and [b] a second step of cutting the end face of the obtained laminate by moving a cutting tool having a cutting blade, which rotates around a rotation axis, relative to the laminate along the length direction of the end face of the laminate.

[First step]
In the manufacturing method of the optical laminate 1, for example, after the first step (above [a]) is performed, polishing can be performed in the second step (above [b]) on the four sides of the optical laminate, which has a rectangular shape when viewed in a plane.

The first step is to obtain a laminate W by stacking a plurality of raw optical laminates cut into a predetermined shape. The number of raw laminates contained in the laminate W is not particularly limited, but the laminate W may be, for example, a laminate of 100 to 500 laminates. The optical laminate constituting the laminate W may be, for example, obtained by cutting a long optical laminate having the layered structure of the optical laminate.

The second step is to cut the end faces of the laminate W obtained in the first step using a rotary tool 60 to form an optical laminate having polished end faces.

The cutting process in the second step can be performed by an apparatus equipped with a support part 50 and two rotating tools 60, as shown in FIG. 3, for example. The support part 50 presses the laminate W from above and below to fix the laminate W so that it does not move during the cutting process and to prevent the stacked laminates from shifting. The rotating tool 60 is used to cut the end surface of the laminate W and can rotate around the rotation axis R.

The support unit 50 can include a flat substrate (a means for moving the laminate W) 51; a gate-shaped frame 52 arranged on the substrate 51; a rotary table 53 arranged on the substrate 51 and rotatable about a central axis; and a cylinder 54 arranged opposite the rotary table 53 on the frame 52 and movable up and down. The laminate W is sandwiched and fixed between the rotary table 53 and the cylinder 54 via a jig 55.

The rotary tool 60 has a disk-shaped rotor that rotates around the rotation axis R. The rotor rotates in the direction indicated by the arrow in FIG. 3. On the disk surface of the rotor (the surface facing the end face of the laminate W and parallel to said end face), multiple cutting blades (e.g., 2 to 10, preferably 3 to 7) are arranged at intervals in the rotation direction of the rotor. The rotation axis R is preferably set to pass through the center of the disk surface of the rotor. The cutting blades are provided so as to protrude from the disk surface of the rotor toward the end face of the laminate W, and the rotor rotates around the rotation axis R with the cutting blades in contact with the end face of the laminate W, thereby cutting the end face of the laminate W.

Two rotating tools 60 are provided on both sides of the substrate 51, facing each other. The rotating tools 60 can move in the direction of the rotation axis R according to the size of the laminate W, and the substrate 51 can move so as to pass between the two rotating tools 60. In the cutting process, the laminate W is fixed to the support 50, the position of the rotating tools 60 in the direction of the rotation axis R is appropriately adjusted, and the substrate 51 is moved so that the laminate W passes between the opposing rotating tools 60 while rotating the rotating tools 60 about their rotation axes R. This allows the cutting process to be performed by moving the rotating tool 60 relative to the laminate W in a direction parallel to the end faces of the laminate W and perpendicular to the stacking direction, while abutting the cutting blades of the rotating tool 60 against the exposed end faces facing each other of the laminate W to cut off these end faces.

The relative movement speed between the laminate W and the rotary tool 60 can be selected, for example, from a range of 200 mm/min to 5000 mm/min (more typically, from a range of 500 mm/min to 3000 mm/min). The rotation speed of the rotary tool 60 can be selected, for example, from a range of 2000 rpm to 8000 rpm (more typically, from a range of 2500 rpm to 6000 rpm).

As described above, the optical laminate of this embodiment can suppress contamination of the end surface during the polishing process.

[Image display device]
Fig. 4 is a schematic cross-sectional view showing an example of an image display device according to the present embodiment. As shown in Fig. 4, the image display device 2 has, from the front side, the optical laminate 1 shown in Fig. 1 and an image display panel 40, in this order. In the image display device 2, the optical laminate 1 is disposed in an orientation such that the linear polarizer 10 side is closer to the front than the retardation plate 30.

When the optical laminate 1 is a circular polarizing plate, in the image display device 2, the incident light from the outside is divided into light reflected by the optical laminate 1 and light transmitted through the optical laminate 1. The optical laminate 1 may have an anti-reflection layer on the front surface, and by providing an anti-reflection layer, the light reflected on the surface of the optical laminate 1 (hereinafter also referred to as "external reflected light") can be reduced. The light transmitted through the optical laminate 1 is reflected by the image display panel 40 and becomes reflected light (hereinafter also referred to as "internal reflected light") and is absorbed by the optical laminate 1. Although it is desirable that all of the internal reflected light is absorbed by the optical laminate 1, a portion of the internal reflected light is emitted from the front surface (hereinafter such light is also referred to as "emitted internal reflected light").

The optical laminate 1 may be configured as a polarizing plate with an adhesive layer, with an adhesive layer provided on the rear surface, which can be used to attach the optical laminate 1 to the image display panel 40.

The image display device is not particularly limited, and examples include image display devices such as organic electroluminescence (organic EL) display devices, inorganic electroluminescence (inorganic EL) display devices, liquid crystal display devices, and electroluminescence display devices.

The image display device can be used as mobile devices such as smartphones and tablets, televisions, digital photo frames, electronic billboards, measuring instruments or gauges, office equipment, medical equipment, computing equipment, etc.

<Other Layers That the Image Display Device May Have>
The image display device 2 may have layers other than the layers described above. Examples of other layers that the image display device 2 may have are given below.

(Touch sensor panel)
The touch sensor panel is a device (sensor) that detects (senses) a finger or the like that touches the screen of an image display device, and is used as an input means for detecting the position of the finger on the screen and inputting the finger to the image display device. The touch sensor panel may be disposed between the optical laminate 1 and the image display panel 40, or may be disposed on the front side of the optical laminate 1. As the touch sensor panel, the detection method is not limited as long as it is a sensor that can detect the touched position, and examples of touch sensor panels include resistive film type, electrostatic capacitance coupling type, optical sensor type, ultrasonic type, electromagnetic induction coupling type, surface acoustic wave type, infrared type, and the like. Resistive film type and electrostatic capacitance coupling type touch sensor panels are preferably used because of their low cost.

One example of a resistive touch sensor panel is composed of a pair of substrates arranged opposite each other, an insulating spacer sandwiched between the pair of substrates, a transparent conductive film provided as a resistive film on the inner front surface of each substrate, and a touch position detection circuit. In an image display device equipped with a resistive touch sensor panel, when the surface of the front panel is touched, the opposing resistive film shorts out and a current flows through the resistive film. The touch position detection circuit detects the change in voltage at this time, and the touched position is detected.

An example of a capacitive touch sensor panel is composed of a substrate, a transparent electrode for position detection provided on the entire surface of the substrate, and a touch position detection circuit. In an image display device equipped with a capacitive touch sensor panel, when the surface of the front panel is touched, the transparent electrode is grounded via the electrostatic capacitance of the human body at the touched point. The touch position detection circuit detects the grounding of the transparent electrode and detects the touched position. A capacitive touch sensor panel is divided into an active area and an inactive area located on the outer periphery of the active area. The active area is an area corresponding to the area (display section) where the screen is displayed on the display panel and is an area where the user's touch is detected, and the inactive area is an area corresponding to the area (non-display section) where the screen is not displayed on the display device.

The thickness of the touch sensor panel may be, for example, 5 μm or more and 2,000 μm or less, or 5 μm or more and 100 μm or less.

<Flexible image display device>
The image display device may be a flexible image display device. The flexible image display device is a foldable image display device. The flexible image display device includes an optical fingerprint authentication system incorporated therein, a foldable image display element, and the polarizing plate of the present invention. The foldable image display element is, for example, an organic EL display panel. The polarizing plate of the present invention is disposed on the viewing side of the organic EL display panel, and is configured to be foldable. The polarizing plate for a flexible image display device may further include a front plate and a touch sensor panel.
It is preferable that the front plate, the polarizing plate of the present invention, and the touch sensor panel are laminated in this order from the viewing side, or the front plate, the touch sensor panel, and the polarizing plate of the present invention are laminated in this order from the viewing side. If a polarizer is present on the viewing side of the touch sensor panel, the pattern of the touch sensor panel becomes difficult to see, and as a result, the visibility of the displayed image is improved. Therefore, it is more preferable to have a configuration in which the polarizing plate of the present invention is provided on the viewing side of the touch sensor panel, that is, the front plate, the polarizing plate of the present invention, and the touch sensor panel are provided in this order. Each member can be laminated using an adhesive, a pressure-sensitive adhesive, or the like. In addition, a light-shielding pattern formed on at least one surface of any of the layers of the front plate, the polarizing plate, and the touch sensor panel can be provided.

In a flexible image display device including, from the viewing side, a front plate, the polarizing plate of the present invention, and a foldable image display panel, the front plate and the polarizing plate of the present invention constitute a front plate-attached polarizing plate including a polarizing plate and a front plate. In this front plate-attached polarizing plate, the front plate is usually disposed on the viewing side of the polarizing plate, and is laminated with the polarizing plate, for example, by a pressure-sensitive adhesive or adhesive.
In a flexible image display device comprising, from the viewing side, a touch sensor panel, the polarizing plate of the present invention, and a foldable image display panel, the touch sensor panel and the polarizing plate of the present invention constitute a polarizing plate with a touch sensor panel comprising a polarizing plate and a touch sensor panel. In a flexible image display device comprising, from the viewing side, the polarizing plate of the present invention, a touch sensor panel, and a foldable image display element, the touch sensor panel and the polarizing plate of the present invention constitute a polarizing plate with a touch sensor panel comprising a polarizing plate and a touch sensor panel. In this polarizing plate with a touch sensor panel, the touch sensor panel may be disposed on the rear side (opposite the viewing side) of the polarizing plate, or may be disposed on the viewing side of the polarizing plate. The touch sensor panel and the polarizing plate are laminated together, for example, with an adhesive or a bonding agent.

The polarizing plate of the present invention can also be used as a polarizing plate with a front plate by laminating a front plate on the viewing side. A polarizing plate with a front plate comprises the polarizing plate of the present invention and a front plate disposed on the viewing side.

(Front panel)
Examples of the front plate include glass and resin film having a hard coat layer on at least one side. As the glass, for example, highly transparent glass or tempered glass can be used. In particular, when a thin transparent surface material is used, chemically tempered glass is preferable. The thickness of the glass can be, for example, 50 μm to 5 mm.

A front panel comprising a hard coat layer on at least one side of a resin film can have flexible properties, rather than being rigid like existing glass. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 μm to 100 μm.

The resin film may be a film formed of a polymer such as norbornene, a cycloolefin derivative having a monomer unit containing a cycloolefin such as a polycyclic norbornene monomer, cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose), ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacrylic, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, or epoxy. Each of these polymers may be used alone or in a mixture of two or more.
The resin film may be an unstretched film or a stretched film, such as a uniaxially stretched film or a biaxially stretched film. As the resin film, polyamideimide film, polyimide film, uniaxially stretched polyester film, and biaxially stretched polyester film are preferred because of their excellent transparency and heat resistance, cycloolefin derivative film and polymethyl methacrylate film are preferred because of their excellent transparency and heat resistance and their ability to accommodate large-sized films, and triacetyl cellulose and isobutyl ester cellulose films are preferred because of their relative ease of availability as transparent and optically non-anisotropic resin films. The thickness of the resin film is usually 5 to 200 μm, and preferably 20 to 100 μm.

(Light blocking pattern)
The light-shielding pattern is a member also called a bezel, and can be formed on the display element side of the front panel. By providing the light-shielding pattern, it is possible to hide each wiring constituting the display device so that it is not visible to the user. The color and material of the light-shielding pattern are not particularly limited, and the light-shielding pattern can be formed of a resin material having various colors such as black, white, gold, etc. In one embodiment, the thickness of the light-shielding pattern may be 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. In addition, a shape can be given to the light-shielding pattern in order to suppress the inclusion of air bubbles and the visibility of the boundary due to a step between the light-shielding pattern and the display part.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The blending amounts expressed as "%" and "parts" in the examples and comparative examples are % by mass and parts by mass unless otherwise specified.

[Preparation of optical laminate]
1. Preparation of Adhesive Composition (1) Preparation of Adhesive 1 (Active Energy Ray-Curable Adhesive) The following components were blended and mixed, and then degassed to prepare an active energy ray-curable adhesive.
[Cationically polymerizable compound]
Neopentyl glycol diglycidyl ether (product name: EX-211L, manufactured by Nagase ChemteX Corporation) 30 parts by mass 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (product name: OXT-221, manufactured by Toagosei Co., Ltd.) 13 parts by mass Bisphenol A type epoxy resin (product name: EP-4100E, manufactured by ADEKA Corporation, viscosity 13 Pa·s (temperature 25° C.)) 45 parts by mass
Aromatic-containing oxetane compound (product name: TCM-104, manufactured by TRONLY) 12 parts by mass [photocationic polymerization initiator]
CPI-100P, manufactured by San-Apro Co., Ltd., 50% propylene carbonate solution, 2.25 parts by mass (solid content)
[Photosensitizer assistant]
1,4-diethoxynaphthalene 1 part by mass

The storage modulus of adhesive 1 at 23°C was 2.45 GPa, the storage modulus at 80°C was 0.03 GPa, and the refractive index for light with a wavelength of 589 nm was 1.54.

(2) Preparation of Adhesive 2 (Active Energy Ray-Curable Adhesive) The following components were blended and mixed, and then degassed to prepare an active energy ray-curable adhesive.
[Cationically polymerizable compound]
3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (product name: CEL2021P, manufactured by Daicel Corporation): 70 parts by mass Neopentyl glycol diglycidyl ether (product name: EX-211, manufactured by Nagase ChemteX Corporation): 20 parts by mass 2-Ethylhexyl glycidyl ether (product name: EX-121, manufactured by Nagase ChemteX Corporation): 10 parts by mass [Photocationic polymerization initiator]
Cationic polymerization initiator (product name: CPI-100P 50% solution propylene carbonate solution, manufactured by San-Apro Co., Ltd.)
: 4.5 parts by mass (actual solid content 2.25 parts by mass)
[Photosensitizing aid]
1,4-diethoxynaphthalene: 2 parts by mass

The storage modulus of adhesive 2 at 23°C was 2.63 GPa, the storage modulus at 80°C was 0.8 GPa, and the refractive index for light with a wavelength of 589 nm was 1.51.

(3) Measurement of storage modulus of adhesive The prepared adhesive was coated on one side of a polyethylene terephthalate film (product name "Toyobo Ester Film E7002", manufactured by Toyobo Co., Ltd.) using a coating machine (bar coater, manufactured by Daiichi Rika Co., Ltd.) so that the film thickness after curing would be approximately 10 μm. Next, the adhesive was cured by irradiating it with ultraviolet rays at an integrated light amount of 600 mJ/cm ² (UV-B) using an ultraviolet irradiation device (manufactured by Fusion UV Systems Co., Ltd.). This was cut into a size of 5 mm x 30 mm, and the polyethylene terephthalate film was peeled off to obtain a cured film of the adhesive. The cured film thus obtained was held with its long side in the tensile direction at a gripping distance of 2 cm using a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement & Control Co., Ltd., and the storage modulus was determined at temperatures of 23°C and 80°C by setting the tensile and contraction frequency to 1 Hz and the heating rate to 3°C/min.

(4) Measurement of refractive index of adhesive The prepared adhesive was applied to one side of a stretched norbornene resin film ("ZEONORFILM" manufactured by ZEON Co., Ltd.) using a bar coater (manufactured by Daiichi Rika Co., Ltd.), and the adhesive was irradiated with an ultraviolet ray irradiation device (manufactured by Fusion UV Systems Co., Ltd.) at an integrated light amount of 600 mJ/cm ² (UV-
B) was irradiated with ultraviolet light to obtain a cured product. The film thickness of the obtained cured product was about 30 μm. The norbornene-based resin film was peeled off from the obtained cured product, and the refractive index (589 nm) of the cured product layer was measured in a 25° C. environment using a multi-wavelength Abbe refractometer ("DR-M2" manufactured by Atago Co., Ltd.).

2. Preparation of Adhesive Layer (1) Fabrication of Adhesive Layer 1 (Acrylic Adhesive Layer) (Preparation of Acrylic Resin Solution 1)
A reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer was charged with a mixed solution of 100 parts of ethyl acetate, 99.0 parts of butyl acrylate, 0.5 parts of 2-hydroxyethyl acrylate, and 0.5 parts of acrylic acid, and the internal temperature was raised to 55°C while the air in the vessel was replaced with nitrogen gas to make it oxygen-free. Then, the entire amount of a solution in which 0.12 parts of azobisisobutyronitrile (polymerization initiator) was dissolved in 10 parts of ethyl acetate was added. After the addition of the polymerization initiator, the temperature was maintained for 1 hour, and then ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54 to 56°C, and the addition of ethyl acetate was stopped when the concentration of the (meth)acrylic resin reached 35% by mass, and the temperature was maintained until 6 hours had elapsed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 20% by mass, and acrylic resin solution 1 was prepared. The resulting acrylic resin had a weight average molecular weight Mw of 1.7 million and a molecular weight distribution Mw/Mn of 3.9. Mw and Mn were measured in terms of standard polystyrene using two "TSKgel GMH _HR -H(S)" columns manufactured by Tosoh Corporation connected in series as columns in a GPC apparatus, tetrahydrofuran as an eluent, a sample concentration of 2 mg/mL, a sample introduction amount of 100 μL, a temperature of 40° C., and a flow rate of 1 mL/min.

(Preparation of Pressure-Sensitive Adhesive Composition 1)
To 80 parts of the solid content of the acrylic resin solution 1 obtained above, 20 parts (solid content) of a bifunctional acrylate (obtained from Shin-Nakamura Chemical Co., Ltd.; product number "A-DOG"), 2.5 parts of a crosslinking agent (manufactured by Tosoh Corporation: product name "Coronate L" (ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75% by mass)) based on active ingredients, 1.5 parts of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: product name "Irgacure 500"), and 0.3 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: product name "KBM-403") were added, and ethyl acetate was further added to make the solid content concentration 13%, to obtain a pressure-sensitive adhesive composition 1. A-DOG is a diacrylate of an acetal compound of hydroxypivalaldehyde and trimethylolpropane, and has the following structure.

(Preparation of Pressure-Sensitive Adhesive Layer 1)
The pressure-sensitive adhesive composition 1 prepared above was applied to the release-treated surface of a separate film made of a release-treated polyethylene terephthalate film ["PLZ-383030" obtained from Lintec Corporation] using an applicator so that the thickness after drying would be 5 μm, and the film was dried at 100° C. for 1 minute to prepare a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet). Next, the surface of the obtained pressure-sensitive adhesive layer opposite the separator film was bonded to the release-treated surface of a separate film made of a release-treated polyethylene terephthalate film ["PLR-381031" obtained from Lintec Corporation]. Subsequently, ultraviolet light was irradiated under the following conditions to prepare a pressure-sensitive adhesive layer 1. The obtained pressure-sensitive adhesive layer had a storage modulus of 0.13 MPa at a temperature of 23° C., a storage modulus of 0.054 MPa at a temperature of 80° C., and a refractive index of 1.48 for light with a wavelength of 589 nm.

<UV irradiation conditions>
- Fusion UV lamp system (manufactured by Fusion UV Systems) H bulb used - Accumulated light amount in UV wavelength region UVA: 250 mJ/cm ² (measurement device: measured value using UV Power Puck II manufactured by Fusion UV)

(2) Preparation of Pressure-Sensitive Adhesive Layer 2 (Acrylic Pressure-Sensitive Adhesive Layer) (Preparation of Acrylic Resin Solution 2)
A reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer was charged with a mixed solution of 81.8 parts of ethyl acetate, 90.0 parts of butyl acrylate, 5.0 parts of methyl acrylate, and 5.0 parts of acrylic acid, and the air in the vessel was replaced with nitrogen gas to make it oxygen-free, while raising the internal temperature to 55°C. Then, a solution of 0.15 parts of azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts of ethyl acetate was added in its entirety. After the addition of the polymerization initiator, the temperature was maintained for 1 hour, and then ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54 to 56°C, and the addition of ethyl acetate was stopped when the concentration of the (meth)acrylic resin reached 35% by mass, and the temperature was maintained for 6 hours from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 20% by mass, and acrylic resin solution 2 was prepared. The resulting acrylic resin had a weight average molecular weight Mw of 1.6 million and a molecular weight distribution Mw/Mn of 4.5. Mw and Mn were measured in terms of standard polystyrene using two "TSKgel GMH _HR -H(S)" columns manufactured by Tosoh Corporation connected in series as columns in a GPC apparatus, tetrahydrofuran as an eluent, a sample concentration of 2 mg/mL, a sample introduction amount of 100 μL, a temperature of 40° C., and a flow rate of 1 mL/min.

(Preparation of Pressure-Sensitive Adhesive Composition 2)
To 100 parts of the solid content of the acrylic resin solution 2 obtained above, 0.15 parts on an active ingredient basis of a crosslinking agent (manufactured by Tosoh Corporation: product name "Coronate L" (a solution of a trimethylolpropane adduct of tolylene diisocyanate in ethyl acetate (solid content concentration 75% by mass)) and 0.2 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: product name "KBM-403") were added, and ethyl acetate was further added so that the solid content concentration became 13%, thereby obtaining a pressure-sensitive adhesive composition 2.

(Preparation of Pressure-Sensitive Adhesive Layer 2)
The pressure-sensitive adhesive composition 2 prepared above was applied to the release-treated surface of a separate film made of a release-treated polyethylene terephthalate film ["PLR-382190" obtained from Lintec Corporation] using an applicator so that the thickness after drying would be as shown in Table 3, and the coating was dried at 100°C for 1 minute to prepare a pressure-sensitive adhesive layer. The surface of the obtained pressure-sensitive adhesive layer opposite the separator film was then bonded to the release-treated surface of a separate film made of a release-treated polyethylene terephthalate film ["PET-251130" obtained from Lintec Corporation], and then irradiated with ultraviolet light under the same conditions as those for preparing the pressure-sensitive adhesive layer 1, to prepare a pressure-sensitive adhesive layer 2. The storage modulus of the obtained pressure-sensitive adhesive layer 2 at a temperature of 23°C was 0.026 MPa, the storage modulus at a temperature of 80°C was 0.019 MPa, and the refractive index for light with a wavelength of 589 nm was 1.48.

(3) Measurement of storage modulus of adhesive layer The storage modulus of the adhesive layer at temperatures of 23° C. and 80° C. was measured using a viscoelasticity measuring device (MCR-301, Anton Paar). After cutting the adhesive sheet into a width of 30 mm × length of 30 mm, the separator was peeled off, and a plurality of sheets were laminated to a thickness of 200 μm and attached to a measurement stage. After that, in a state where the sheets were attached to a parallel plate having a diameter of 25 mm, measurements were performed in a temperature range of 20° C. to 85° C. under conditions of a frequency of 1.0 Hz, a deformation amount of 1%, and a heating rate of 10° C./min, to determine the storage modulus G′ at temperatures of 23° C. and 80° C.

(4) Measurement of Refractive Index of Pressure-Sensitive Adhesive Layer The refractive index (589 nm) of the resulting pressure-sensitive adhesive layer was measured in an environment of 25° C. using a multi-wavelength Abbe refractometer ("DR-M2" manufactured by Atago Co., Ltd.).

3. Preparation of Polarizing Film A polyvinyl alcohol film having a thickness of 20 μm, a degree of polymerization of 2400, and a degree of saponification of 99% or more was uniaxially stretched to a stretching ratio of 4.5 times on a heated roll, and while maintaining the tension, was immersed for 60 seconds in a dye bath at 28° C. containing 0.05 part by mass of iodine and 5 parts by mass of potassium iodide per 100 parts by mass of water.

Then, it was immersed for 110 seconds in boric acid aqueous solution 1 at 64°C, which contains 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water. Then, it was immersed for 30 seconds in boric acid aqueous solution 2 at 67°C, which contains 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water. Thereafter, it was washed with pure water at 10°C and dried to obtain a polarizer. The polarizer had a thickness of 8 μm and a boron content of 4.3% by mass.

4. Preparation of Water-Based Adhesive A polyvinyl alcohol aqueous solution was prepared by dissolving 3 parts by mass of carboxyl group-modified polyvinyl alcohol ("KL-318" manufactured by Kuraray Co., Ltd.) in 100 parts by mass of water. A water-soluble polyamide epoxy resin ("Sumirez Resin 650 (30)" manufactured by Taoka Chemical Co., Ltd., solid content concentration 30% by mass) was mixed with the obtained aqueous solution in a ratio of 1.5 parts by mass per 100 parts by mass of water to obtain a water-based adhesive.

5. Preparation of Linear Polarizing Plate A hard coat (HC) layer-attached cyclic polyolefin resin film (HC-COP) was laminated as a first protective film and a triacetyl cellulose film (TAC) was laminated as a second protective film on both sides of the polarizing film prepared above, using a roll laminator, via the aqueous adhesive obtained above. After lamination, a drying treatment was performed at 80°C for 3 minutes. The obtained roll was cut into a rectangle so that the longitudinal direction was the absorption axis of PVA, and a linear polarizing plate 10 was obtained in which a protective film was laminated on both sides of the polarizing film. The linear polarizing plate 10 had a layer structure of a first protective film/adhesive layer/polarizer/adhesive layer/second protective film. The refractive index of the second protective film for light with a wavelength of 589 nm was 1.48.

6. Preparation of the first liquid crystal retardation film and the second liquid crystal retardation film (1) Preparation of an oriented polymer composition (1) Water was added to commercially available polyvinyl alcohol (polyvinyl alcohol 1000 fully saponified type, manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was heated at 100°C for 1 hour to obtain an oriented polymer composition (1).

(2) Preparation of photoalignable polymer composition (1) The photoalignable material having the following structure (weight average molecular weight: 50,000, m:n = 50:50) was produced according to the method described in JP 2021-196514 A. Photoalignable polymer composition (1) was prepared by mixing 2 parts of the photoalignable material and 98 parts of propylene glycol monomethyl ether (PGME, solvent) as components and stirring the resulting mixture at 80 ° C. for 1 hour.
Photo-alignable materials:

(3) Production of polymerizable liquid crystal compound Polymerizable liquid crystal compound (A1) and polymerizable liquid crystal compound (A2) having the structures shown below were prepared in the same manner as described in JP-A-2010-244038.

Polymerizable liquid crystal compound (A1):

Polymerizable liquid crystal compound (A2):

(4) Preparation of liquid crystal retardation film forming composition (Y1) The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) were mixed in a mass ratio of 80:20 to obtain a mixture. To 100 parts of the obtained mixture, a leveling agent "Megafac F-556" (manufactured by DIC Corporation) part, a photopolymerization initiator "Omnirad 907" (manufactured by IGM Resin B.V.) and an ionic compound (B) were added. Furthermore, cyclopentanone was added, and the mixture was stirred at a temperature of 80 ° C. for 1 hour to prepare a retardation film forming composition (Y1). The amount of each component added is as shown in Table 1 below.

Ionic compound (B):

(5) Preparation of liquid crystal retardation film forming composition (Y2) Polymerizable liquid crystal compound Paliocolor LC242 (manufactured by BASF Japan), leveling agent "BYK-361N" (manufactured by BYK-Chemie), and photopolymerization initiator "Omnirad907" (manufactured by IGM Resin B.V.) were added. Furthermore, propylene glycol 1-monomethyl ether 2-acetate (PGME) was added, and the mixture was stirred at a temperature of 80°C for 1 hour to prepare retardation film forming composition (Y2). The amount of each component added is as shown in Table 2 below.

Polymerizable liquid crystal compound LC242:

(6) Preparation of the first liquid crystal retardation film (Z1) The oriented polymer composition (1) was applied to a rectangular cut triacetyl cellulose film (TAC) (Konica Minolta, Inc., KC4UY) to form an oriented polymer film with a thickness of 100 nm after drying. The surface of the obtained oriented polymer film was subjected to a rubbing treatment at an angle of −15° from the longitudinal direction of the TAC so that the slow axis of the retardation film (Z1) formed below was formed, and the retardation layer forming composition (Y1) was applied thereon by a bar coater. The obtained coating film was dried at 100° C. for 1 minute, and then cooled to room temperature to obtain a dried film. Next, the dried film was irradiated with ultraviolet light at an exposure dose of 1000 mJ/cm ² (based on 365 nm) under a nitrogen atmosphere using a high-pressure mercury lamp ("Uniqure VB-15201BY-A" manufactured by Ushio Inc.), thereby forming a first liquid crystal retardation film (X1) in which the polymerizable liquid crystal compound was cured in a state of being aligned horizontally relative to the substrate plane, and a retardation film (Z1) consisting of TAC/alignment film/first liquid crystal retardation film (X1) (horizontally aligned liquid crystal cured film) was obtained. The thickness of the obtained first liquid crystal retardation film (X1) was measured with a laser microscope and found to be 1.8 μm. The in-plane retardation value was measured using KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd. As a result, the in-plane retardation value at a wavelength of 550 nm was Re(550)=270 nm, and the in-plane retardation value at a wavelength of 450 nm was Re(450)=291 nm. In addition, since the retardation value of TAC at a wavelength of 550 nm is approximately 0, there is no influence on the optical characteristics. The orientation angle was −15° with respect to the longitudinal direction of the TAC. The first liquid crystal retardation film satisfied the formula (2).

(7) Preparation of second liquid crystal retardation film (Z2) The photoalignable polymer composition (1) was applied to a rectangular cut triacetyl cellulose film (TAC) (Konica Minolta, Inc., KC4UY). The resulting coating film was dried at 120°C for 2 minutes, and then cooled to room temperature to form a dry coating. Furthermore, a UV irradiation device was used to continuously irradiate 100 mJ of polarized ultraviolet light (based on 313 nm) at 75° to the longitudinal direction of the TAC to form a 100 nm photoalignment film. The retardation film-forming composition (Y2) was applied thereon by a bar coater. The resulting coating film was dried at 100°C for 1 minute, and then cooled to room temperature to obtain a dry coating. Next, the dried film was continuously irradiated with ultraviolet light having an exposure dose of 1000 mJ/cm ² (based on 365 nm) under a nitrogen atmosphere using a high-pressure mercury lamp, thereby forming a second liquid crystal retardation film (X2) in which the polymerizable liquid crystal compound was cured in a state of being aligned horizontally relative to the substrate surface, and a retardation film (Z2) consisting of TAC/alignment film/second liquid crystal retardation film (X2) (horizontally aligned liquid crystal cured film) was obtained. The thickness of the obtained second liquid crystal retardation film (X2) was measured with a laser microscope and found to be 1.0 μm. The in-plane retardation value was measured using KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd. As a result, the in-plane retardation value at a wavelength of 550 nm was Re(550)=142 nm, and the in-plane retardation value at a wavelength of 450 nm was Re(450)=153.4 nm. Note that the retardation value at a wavelength of 550 nm of TAC is approximately 0, so there is no effect on the optical properties. The alignment angle was 75° with respect to the longitudinal direction of the TAC. The second liquid crystal retardation film satisfied formula (3).

7. Preparation of optical laminates (Examples 1 to 4, Example 5 (comparison), Examples 6 to 10, Comparative Examples 1 to 3)
(1) Preparation of retardation plate The first liquid crystal retardation film (X1) of the first liquid crystal retardation film (Z1) and the second liquid crystal retardation film (X2) of the second liquid crystal retardation film (Z2) were each subjected to corona treatment. Then, the corona treatment surfaces of both were laminated via the second adhesive layer described in Table 3 to obtain a retardation plate laminated in the order of TAC/alignment film/first liquid crystal retardation film (X2)/second adhesive layer/second liquid crystal retardation film (X1)/alignment film/TAC.

When the second adhesive layer was formed using the adhesives 1 and 2, the retardation plate was prepared as follows. An adhesive was applied to the corona-treated surface of either the first liquid crystal retardation film (X1) or the second liquid crystal retardation film (X2), and the first liquid crystal retardation film (Z1) and the second liquid crystal retardation film (Z2) were laminated together. The second liquid crystal retardation film (Z2) was irradiated with ultraviolet light to cure the ultraviolet-curable adhesive, forming an adhesive layer (second adhesive layer). The ultraviolet light was irradiated so that the UVA with a wavelength of 320 nm to 390 nm was 420 mJ/cm ^2. The thickness of the adhesive layer after curing was measured with a laser microscope (manufactured by Olympus Corporation, "LEXT"), and was as shown in Table 3.

When the second adhesive layer was formed using adhesive layers 1 and 2, the retardation plate was produced as follows. The first liquid crystal retardation film (Z1) and the second liquid crystal retardation film (Z2) were bonded together with adhesive layers 1 and 2 interposed between the first liquid crystal retardation film (X1) and the second liquid crystal retardation film (X2).

(Corona treatment)
The corona treatment device used was AGF-B10 manufactured by Kasuga Denki Co., Ltd. The corona treatment was carried out once using the corona treatment device under conditions of an output of 0.3 kW and a treatment speed of 3 m/min.

(2) Preparation of optical laminate The TAC substrate of the first liquid crystal retardation film (X1) was peeled off from the retardation plate in which TAC/alignment film/first liquid crystal retardation film (X1)/second adhesive layer/second liquid crystal retardation film (X2)/alignment film/TAC was laminated in this order. The exposed surface of the alignment film of the first liquid crystal retardation film (X1) and the surface of the second protective film (TAC film) of the linear polarizer 1 were laminated via the first adhesive layer described in Table 3 so that their longitudinal directions were in the same direction. The TAC substrate of the second liquid crystal retardation film (X2) was peeled off from the retardation plate to obtain an optical laminate. After forming the optical laminate, one of the separator films of the adhesive layer 2 prepared to have a thickness of 25 μm was peeled off and attached to the alignment film surface of the second liquid crystal retardation film (X2) of the optical laminate. The end surface was polished according to the method described in FIG. 3 to obtain the optical laminates of Examples 1 to 10 and Comparative Examples 1 to 3.

8. Evaluation (1) Inspection of interference unevenness After laminating an acrylic adhesive (film thickness 25 μm) on the surface of the retardation plate side of the optical laminate of the example and the comparative example, it was cut into a size of 150 mm × 150 mm. The cut optical laminate with the acrylic adhesive was attached to an aluminum reflector to obtain a test piece for observing interference unevenness. The test piece for observing interference unevenness was placed on a stand so that the angle between the floor surface and the floor surface was 45° when the floor surface was set to 0°. A linear polarizing plate was placed between the three-wavelength fluorescent lamp as a light source and the test piece for observing interference unevenness. The test piece for observing interference unevenness was irradiated with light from the three-wavelength fluorescent lamp from a direction of 90° (above the test piece for observing interference unevenness). When the observer observed the test piece from the 0° direction, a polarizing plate was placed so that it was perpendicular to the absorption axis of the linear polarizing plate placed on the three-wavelength fluorescent lamp, and the sample was observed through the placed polarizing plate.
A: No visible interference unevenness B: Slightly visible interference unevenness but weaker than C C: Slightly visible interference unevenness D: Visible interference unevenness

(2) Measurement of reflectance An acrylic adhesive (film thickness 25 μm) was attached to the surface of the retardation plate side of the optical laminate of the examples and comparative examples, and then cut into a size of 150 mm × 150 mm. The cut optical laminate with acrylic adhesive was attached to a glass plate (Corning, Eagle XG, 0.7 mmt) so that the adhesive side was the glass plate side to prepare a sample for measurement. The glass plate side of the measurement sample was placed on a reflector plate (Alanod, MIRO5 5011GP) so that it was in contact with the reflector plate, and the reflectance was measured using a spectrophotometer (CM2600d, Konica Minolta, Inc.). For the measurement, a mask with an opening diameter φ of 8.0 mm when light enters the integrating sphere from the evaluation sample was attached, and the reflectance of the center part of the measurement sample was measured in SCI mode.
A: 4.95% or more and less than 5.00% B: 5.00% or more and less than 5.05% C: 5.05% or more and less than 5.20% D: 5.20% or more

(3) Evaluation of End Face Polishing 300 optical laminates were stacked, and the end faces were polished using a rotary tool. One optical laminate was removed from the polished laminate, and the end face was observed using an optical microscope (VHX-7000, 100x field of view) to evaluate the maximum size of cracks and glue chipping that occurred.
A: The maximum size of cracks and glue chips is less than 100 μm. B: The maximum size of cracks and glue chips is 100 μm or more and less than 250 μm. C: The maximum size of cracks and glue chips is 250 μm or more and less than 500 μm. D: The maximum size of cracks and glue chips is 500 μm or more.

1 Optical laminate, 2 Image display device, 10 Linear polarizing plate, 11 First protective film, 12, 14 Adhesive layer, 13 Polarizer, 15 Second protective film, 21 First adhesive layer, 30 Retardation plate, 31 First liquid crystal retardation film, 32 Second liquid crystal retardation film, 34 Second adhesive layer, 40 Image display panel, 50 Support, 60 Rotating tool, R Rotating shaft, W Laminate.

Claims (2)

An optical laminate comprising a first protective film, an adhesive layer, a polarizer, an adhesive layer, a second protective film, a first adhesive layer, a first liquid crystal retardation film, a second adhesive layer, and a second liquid crystal retardation film laminated adjacent to each other in this order,
The second protective film and the first adhesive layer have a refractive index of N _aII for light having a wavelength of 589 nm, and a refractive index of the first adhesive layer for light having a wavelength of 589 nm, which can be _expressed by the following formula (1):
|N _aII -N _bI |≦0.04...(1)
Fulfilling
The first liquid crystal retardation film and the second liquid crystal retardation film each independently represent a compound represented by the following formula (2) or (3):
nx>ny≧nz...(2)
nx<ny≦nz...(3)
Fulfilling
the second adhesive layer is an adhesive layer, has a thickness of 3.6 μm to 7 μm, has a refractive index with respect to light having a wavelength of 589 nm of 1.48 to 1.59, and has a storage modulus at a temperature of 80° C. of 0.001 GPa or more and 5 GPa or less;
the first adhesive layer is a pressure-sensitive adhesive layer having a thickness of 2 μm or more and 10 μm or less, the refractive index _NbI being 1.48 to 1.54, and the storage modulus at a temperature of 80° C. being 0.01 MPa or more and 0.8 MPa or less.
(In formulas (2) and (3), nx represents a principal refractive index in a direction parallel to a plane of the first liquid crystal retardation film or the second liquid crystal retardation film in an index ellipsoid formed by the first liquid crystal retardation film or the second liquid crystal retardation film, ny represents a refractive index in a direction parallel to the plane in the index ellipsoid and perpendicular to the direction of nx, and nz represents a refractive index in a direction perpendicular to the plane in the index ellipsoid.) The optical laminate according to claim 1, wherein the second adhesive layer has a refractive index of 1.50 to 1.57 for light with a wavelength of 589 nm.

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