CN115047554A - Optical laminate and elliptically polarizing plate - Google Patents

Optical laminate and elliptically polarizing plate Download PDF

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Publication number
CN115047554A
CN115047554A CN202210222730.0A CN202210222730A CN115047554A CN 115047554 A CN115047554 A CN 115047554A CN 202210222730 A CN202210222730 A CN 202210222730A CN 115047554 A CN115047554 A CN 115047554A
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phase
phase delay
section
polarizing plate
lambda
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Chinese (zh)
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出崎光
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Sumitomo Chemical Co Ltd
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Sumitomo Chemical Co Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/868—Arrangements for polarized light emission
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/42—Polarizing, birefringent, filtering

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Polarising Elements (AREA)
  • Laminated Bodies (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

The invention provides an optical laminate and an elliptically polarizing plate which can ensure good display performance even if the optical laminate is obliquely viewed in at least 2 directions orthogonal to each other in a plane when the optical laminate is arranged on a light reflecting layer. An optical laminate according to one embodiment of the present invention includes a lambda/2 section having a1 st slow axis, and a lambda/4 section having a2 nd slow axis and laminated on the lambda/2 section such that the 2 nd slow axis is in a range of approximately 60 DEG with respect to the 1 st slow axis, wherein N of the lambda/2 section Z N with a coefficient of approximately 0.5, lambda/4 Z The coefficient is 0.3 or more and 0.7 or less.

Description

Optical laminate and elliptically polarizing plate
Technical Field
The present invention relates to an optical laminate and an elliptically polarizing plate.
Background
As a conventional technique in this field, there is a technique described in patent document 1. Patent document 1 discloses an optical laminate in which a λ/2 section and a λ/4 section are laminated. The optical laminate described in patent document 1 has a phase difference close to λ/4 over the entire visible light range, and therefore, when combined with a linear polarizer, functions as an elliptically polarizing plate having an ellipticity of 97% or more over the entire visible light range. When the film is disposed on a light reflecting layer of an OLED display device or the like, external light reflection can be suppressed in a wide range of a visible light region.
Documents of the prior art
Patent document
Patent document 1: international publication No. 2018/003416
Disclosure of Invention
Problems to be solved by the invention
The optical laminate described in patent document 1 has insufficient compensation of the viewing angle. Therefore, the performance of the optical laminate described in patent document 1 is limited to the case where the display device is viewed from the substantially front side, and there is a problem that the external light reflectance is increased when viewing is performed obliquely, and the display performance is lowered.
The purpose of the present invention is to provide an optical laminate and an elliptically polarizing plate that, when disposed on a light reflecting layer, can ensure good display performance even when viewed obliquely in at least 2 directions orthogonal in the plane.
Means for solving the problems
An optical laminate according to one aspect of the present invention includes:
a lambda/2 part having a1 st slow axis; and
a lambda/4 section having a2 nd slow axis and laminated on the lambda/2 section so that the 2 nd slow axis is in a range of approximately 60 DEG with respect to the 1 st slow axis,
n of the above lambda/2 part Z The factor is approximately 0.5 of the total,
n of the lambda/4 part Z The coefficient is 0.3 or more and 0.7 or less.
In the optical laminate, N passing through the λ/2 part Z A coefficient of approximately 0.5, N of the lambda/4 part Z The coefficient is 0.3 or more and 0.7 or less, so that when the optical layered body is disposed on the light reflection layer, good display performance can be ensured even when the optical layered body is viewed obliquely in at least 2 directions orthogonal in the plane.
Optionally, each of the λ/2 section and the λ/4 section has a1 st phase retardation element, the 1 st phase retardation element has inverse dispersibility and imparts a phase difference of substantially λ/4, a direction of a slow axis of the 1 st phase retardation element included in the λ/2 section substantially coincides with a direction of the 1 st slow axis, and a direction of a slow axis of the 1 st phase retardation element included in the λ/4 section substantially coincides with a direction of the 2 nd slow axis.
Optionally, the λ/2 part has 21 st phase delay elements and 2 nd phase delay elements, the lambda/4 section has a1 st phase delay element, the 21 st phase delay elements of the lambda/2 section and the 1 st phase delay element of the lambda/4 section have inverse dispersion properties and impart a phase difference of substantially lambda/4, the 2 nd phase delay elements 2 of the λ/2 section are positive C plates, the slow axis directions of the 21 st phase delay elements and the 2 nd phase delay elements 2 of the λ/2 section substantially coincide with the 1 st slow axis direction, the direction of the slow axis of the 1 st phase delay element included in the λ/4 section substantially coincides with the direction of the 2 nd slow axis. In this case, when the optical layered body is disposed on the light reflection layer, good display performance can be easily ensured even when the optical layered body is viewed obliquely in each of the in-plane orthogonal 2 directions and the in-plane oblique direction with respect to the orthogonal 2 directions.
The 21 st phase delay elements and the 2 nd phase delay elements may be stacked in the order of the 1 st phase delay element, the 2 nd phase delay element, and the 1 st phase delay element. In this case, when the optical layered body is disposed on the light reflection layer, it is easy to ensure further excellent display performance even when the optical layered body is viewed obliquely in each of the in-plane orthogonal 2 directions and the in-plane oblique direction with respect to the orthogonal 2 directions.
Optionally, the λ/2 section includes 21 st phase delay elements and 2 nd phase delay elements, the λ/4 section includes 1 st phase delay elements and 2 nd phase delay elements, the 21 st phase delay elements included in the λ/2 section and the 1 st phase delay elements included in the λ/4 section are elements having inverse dispersibility and giving a phase difference of substantially λ/4, the 2 nd phase delay elements included in the λ/2 section and the 2 nd phase delay elements included in the λ/4 section are positive C plates, the direction of the slow axis of each of the 21 st phase delay elements and the 2 nd phase delay elements included in the λ/2 section substantially coincides with the direction of the 1 st slow axis, and the direction of the slow axis of each of the 1 st phase delay elements and the 2 nd phase delay elements included in the λ/4 section substantially coincides with the upward direction of the slow axis of the 1 st phase delay element and the 2 nd phase delay element included in the λ/4 section The 2 nd slow axis direction is substantially the same, the 21 st phase delay elements and the 2 nd phase delay elements of the λ/2 section are stacked in the order of the 1 st phase delay element, the 2 nd phase delay element, and the 1 st phase delay element and the 2 nd phase delay element of the λ/4 section are stacked in the order of the 1 st phase delay element and the 2 nd phase delay element from the λ/2 section side.
In the above configuration, when the optical layered body is disposed on the light reflection layer, good display performance can be ensured in each of the in-plane orthogonal 2 directions and the in-plane oblique direction with respect to the orthogonal 2 directions even when the optical layered body is viewed obliquely.
An elliptically polarizing plate according to another aspect of the present invention includes a polarizing plate and the optical laminate laminated on the polarizing plate, wherein the polarizing plate, the λ/2 section, and the λ/4 section are arranged in this order from the polarizing plate to the λ/2 section.
The elliptically polarizing plate includes the optical laminate. Therefore, when the elliptically polarizing plate is disposed on the light reflecting layer, it is possible to ensure good display performance even when the elliptically polarizing plate is viewed obliquely in at least 2 directions orthogonal to the plane.
Effects of the invention
According to the present invention, it is possible to provide an optical laminate and an elliptically polarizing plate which can ensure good display performance even when the optical laminate is disposed on a light reflecting layer and viewed obliquely in at least 2 directions orthogonal to each other in a plane.
Drawings
Fig. 1 is a schematic diagram showing a schematic configuration of a display device including an optical laminate according to an embodiment.
Fig. 2 is a schematic diagram showing the arrangement relationship of the slow axis of the λ/2 part (1 st slow axis), the slow axis of the λ/4 part (2 nd slow axis), and the transmission axis of the polarizing plate.
Fig. 3 is a graph showing the wavelength dispersion characteristics of in-plane Retardation (recording) of the trial-produced elliptically polarizing plate.
Fig. 4 is a drawing for explaining the tilt angle when the elliptically polarizing plate is tilted in the experiment.
Fig. 5 is a drawing for explaining in-plane angles and tilt directions in experiments and calculations.
Fig. 6 is a drawing for explaining in-plane angle regions used in experiments and calculations.
FIG. 7 is a graph showing the results of examples and comparative examples.
Description of the reference numerals
20 … elliptically polarizing plate, 31 … polarizer, 40 … optical laminate, 41 … λ/2 section, 41a … slow axis (1 st slow axis), 42 … λ/4 section, 42a … slow axis (2 nd slow axis), Q … phase retarder (1 st phase retarder), Z … phase retarder (2 nd phase retarder).
Detailed Description
Hereinafter, embodiments of the present invention will be described. First, terms used in the present invention will be explained.
[ phase retarder ]
The phase retarder in the present invention refers to an optical medium having birefringence. Birefringence refers to an optical property in which the difference in refractive index between at least 2 of orthogonal 3 directions exceeds 0.02.
[ refractive index of phase retarder ]
The refractive indices in the above orthogonal 3 directions in the phase retarder are referred to as nx, ny, and nz. nx represents a principal refractive index in a direction parallel to the plane of the phase retarder in a refractive index ellipsoid formed by the phase retarder. ny represents a refractive index in a direction parallel to the phase retarder plane and orthogonal to the nx direction in a refractive index ellipsoid formed by the phase retarder. nz denotes a refractive index in a direction perpendicular to a phase retarder plane in a refractive index ellipsoid formed by the phase retarder.
[ in-plane retardation and thickness-direction retardation of phase retarder ]
The delay Re is a physical quantity representing anisotropy of the phase retarder. The retardation Re includes an in-plane retardation Reo and a thickness direction retardation Reth.
The in-plane retardation Reo (λ) at a wavelength λ nm is represented by formula (1). D in formula (1) represents the thickness (nm) of the phase retarder.
Reo(λ)＝(nx-ny)×d···(1)
The thickness direction retardation Reth (λ) at the wavelength λ nm is represented by formula (2). D in the formula (2) is the thickness (nm) of the retarder, similarly to d in the formula (1).
Reth(λ)＝-{nz-(nx+ny)/2}×d···(2)
[ Positive A plate ]
The positive a plate is a phase retarder whose refractive index in each direction satisfies the relationship of expression (3). In a case where it is not described, the slow axis of the positive A plate is parallel to nx, and ny ≈ nz indicates a state where the difference between ny and nz is less than 0.02.
nx＞ny≈nz····(3)
A positive a plate may be used as the λ/4 plate. The in-plane retardation at wavelength 550nm of the λ/4 plate may be substantially λ/4. The in-plane retardation Reo (550) at a wavelength of 550nm of a λ/4 plate whose in-plane retardation is substantially λ/4 may be in the range of the formula (4).
92nm≤Reo(550)≤183nm···(4)
A preferable range of the Reo (550) value of the λ/4 plate is preferably 100nm or more and 160nm or less, and more preferably 110nm or more and 150nm or less. The in-plane retardation Reo (λ) of the positive a plate at the wavelength λ nm and the thickness direction retardation Reth (λ) have a relationship of formula (5) derived from formulae (1), (2), and (3).
Reth(λ)＝0.5×Reo(λ)···(5)
The thickness direction retardation Reth (550) at a wavelength of 550nm of the λ/4 plate may be in the range of expression (6).
46nm≤Reth(550)≤92nm···(6)
A preferable range of the value of Reth (550) is preferably 50nm or more and 80nm or less, and more preferably 55nm or more and 75nm or less.
[ Positive C plate ]
The positive C plate is a phase retarder whose refractive index in each direction satisfies the relationship of expression (7). In a case not illustrated, the slow axis of the positive C plate is parallel to nz, and nx ≈ ny indicates a state where the difference between nx and ny is less than 0.02.
nx≈ny＜nz···(7)
[ wavelength Dispersion ]
The dispersion relationship of wavelength to retardation is also referred to simply as wavelength dispersion. A phase retarder satisfying the formulas (8) and (9) is referred to as inverse wavelength dispersion, also simply referred to as inverse dispersion.
Re(450)/Re(550)≤1.00···(8)
1.00≤Re(650)/Re(550)···(9)
The Re (450)/Re (550) of the phase retarder in the present invention is preferably 0.90 or less, more preferably 0.85 or less, and usually 0.60 or more, preferably 0.70 or more. The phase retarder of the present invention preferably has Re (650)/Re (550) of 1.02 or more, more preferably 1.10 or more, and usually 1.30 or less, preferably 1.20 or less.
A phase retarder satisfying the expressions (10) and (11) is referred to as positive wavelength dispersion, and is also simply referred to as positive dispersion.
Re(450)/Re(550)＞1.00···(10)
1.00>Re(650)/Re(550)···(11)
[ phase retarder laminate ]
An optical laminate in which a plurality of phase retarders are laminated may be referred to as a phase retarder laminate.
[ Nz coefficient ]
The Nz coefficient of the phase retarder can be expressed by equation (12). Note that the in-plane retardation of the entire phase retarder stack at a wavelength λ (nm) (e.g., wavelength 550nm) is ReoG, and the thickness direction retardation of the entire phase retarder stack is RethG.
The Nz coefficient ≡ (RethG/ReoG) + 0.5. cndot. (12)
Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description thereof is omitted. The dimensional ratios in the drawings do not necessarily correspond to the dimensional ratios illustrated.
Fig. 1 is a schematic diagram showing a schematic configuration of a display device including an optical laminate according to an embodiment. The display device 100 shown in fig. 1 includes a light-reflective image display layer 10 (hereinafter, simply referred to as "image display layer 10") and an elliptically polarizing plate 20. In the present invention, the elliptically polarizing plate also includes the concept of a circularly polarizing plate.
[ image display layer ]
The image display layer 10 forms an image therein, and displays the image on the image display surface 10 a. The image display layer 10 includes an element structure for forming an image, and the like. Therefore, the electrodes included in the element structures, the wiring connecting the element structures, and the like function as reflection portions that reflect light. Therefore, the image display layer 10 has light reflectivity for reflecting light incident on the display device 100 from the elliptically polarizing plate 20 side, and functions as a light reflecting layer in the display device 100. The image display layer 10 may have flexibility that allows bending or may have rigidity that does not allow bending.
The image display layer 10 is not limited in layer structure and material, as long as it is configured to form an image on the image display surface 10 a. The image display layer 10 may be a multi-layered structure including a portion (or layer) formed of electrodes and wires using a metal such as gold, silver, copper, iron, nickel, chromium, molybdenum, titanium, or aluminum, or an alloy thereof, a dielectric portion such as a resin film, a barrier material, or a light-emitting element, and other layers.
The image display layer 10 is, for example, a flat panel display device. An example of the flat panel display device is a thin (or panel-shaped) organic electroluminescent display device (hereinafter, also referred to as an "OLED display device"). The display device exemplified as the image display layer 10 is a device in which no member for performing optical compensation is included on the image display surface.
When the image display layer 10 is an OLED display device, typically, an electrode (for example, a metal electrode) provided in the OLED display device is the above-described reflection portion. The OLED display device has a thin-film structure in which an organic light-emitting material layer is sandwiched between a pair of electrodes facing each other. Electrons are injected from one electrode into the organic light emitting material layer, and holes are injected from the other electrode into the organic light emitting material layer, whereby electrons and holes are combined in the organic light emitting material layer to perform self-luminescence. Of the 2 electrodes sandwiching the organic light emitting material layer, the electrode on the image display surface 10a side has a function of transmitting light from the organic light emitting material layer, and the other electrode has a function of reflecting light from the organic light emitting material layer toward the image display surface 10 a. Therefore, the other electrode typically functions as a reflective portion in the OLED display device.
The OLED display device has advantages of being excellent in visibility, being capable of being further thinned, and being driven by a dc low voltage, as compared with a liquid crystal display device or the like that requires a backlight.
The elliptically polarizing plate 20 is laminated on the image display layer 10. Therefore, in the display device 100, an image is visually recognized from the side of the elliptical polarizing plate 20. Therefore, the side opposite to the image display layer 10 is also referred to as a "viewing side" with reference to the elliptically polarizing plate 20. The elliptically polarizing plate 20 includes a polarizer 31 and an optical laminate 40. As shown in fig. 1, in the elliptically polarizing plate 20, a polarizing plate 31 and an optical laminate 40 are arranged in this order from the viewing side.
The polarizing plate 31 is laminated on the optical laminate 40. The polarizing plate 31 may be an absorption type film having the following properties: linearly polarized light having a vibration plane parallel to the absorption axis thereof is absorbed, and linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis) is transmitted. As the polarizing plate 31, a film in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film can be suitably used. The polarizing plate 31 can be manufactured, for example, by a method including the steps of: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing the polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye; treating the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with a crosslinking liquid such as an aqueous boric acid solution; and a step of washing with water after the treatment with the crosslinking liquid.
As the polyvinyl alcohol resin, a resin obtained by saponifying a polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other copolymerizable monomers. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group, and the like.
In the present invention, "(meth) acrylic acid" means at least one selected from acrylic acid and methacrylic acid. The same applies to "(meth) acryloyl group", "meth (acrylate)" and the like.
The thickness of the polarizing plate 31 is usually 30 μm or less, preferably 15 μm or less, more preferably 13 μm or less, still more preferably 10 μm or less, and particularly preferably 8 μm or less. The thickness of the polarizing plate 31 is usually 2 μm or more, preferably 3 μm or more.
As the polarizing plate 31, for example, as described in japanese patent application laid-open No. 2016 and 170368, a polarizing plate in which a dichroic dye is aligned in a cured film obtained by polymerizing a liquid crystal compound can be used. As the dichroic dye, a dye having absorption in the wavelength range of 380 to 800nm can be used, and an organic dye is preferably used. Examples of the dichroic dye include azo compounds. The liquid crystal compound is a liquid crystal compound capable of being polymerized in an aligned state, and may have a polymerizable group in a molecule. Further, as described in WO2011/024891, a polarizing film may be formed from a dichroic dye having liquid crystallinity.
The visibility correction polarization degree of the polarizing plate 31 is preferably 90% or more, more preferably 95% or more. The upper limit is not particularly limited, but is 99.9999% or less.
The visibility-correcting monomer transmittance of the polarizing film is preferably 35% or more, and more preferably 40% or more. The upper limit is not particularly limited, but is 49.9% or less. By providing the laminate with the polarizing plate 31 having such properties, reflected light is less likely to leak, and coloring can be made inconspicuous.
As shown in fig. 1, a protective film 32 may be provided on one or both sides of the polarizing plate 31. A laminate in which the protective film 32 is laminated on the polarizer 31 may be referred to as a linear polarizing plate 30.
The protective film 32 may be a thermoplastic resin having light transmittance (preferably optically transparent). The protective film 32 may be a polyolefin resin including, for example, a chain polyolefin resin (such as a polypropylene resin) and a cyclic polyolefin resin (such as a norbornene resin); cellulose resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; a polycarbonate-based resin; (meth) acrylic resins such as methyl methacrylate resins; a polystyrene-based resin; a polyvinyl chloride resin; acrylonitrile butadiene styrene resins; acrylonitrile-styrene resin; polyvinyl acetate resin; a polyvinylidene chloride resin; a polyamide resin; a polyacetal resin; modified polyphenylene ether resin; a polysulfone-based resin; a polyether sulfone-based resin; a polyarylate-based resin; a polyamide imide resin; a film of a polyimide resin or the like.
The phase difference value of the protective film 32 can be appropriately controlled to an appropriate value. In order to improve the visibility of a screen when a user wears polarized sunglasses or the like, the in-plane retardation value at a wavelength of 550nm may be set to 70 to 140 nm.
The thickness of the protective film 32 is usually 1 to 100 μm, preferably 5 to 60 μm, more preferably 10 to 55 μm, and further preferably 15 to 40 μm from the viewpoint of strength, handling properties, and the like.
When the protective films 32 are bonded to both surfaces of the polarizing plate 31, the 2 protective films 32 may be made of the same kind of thermoplastic resin or different kinds of thermoplastic resins. The thicknesses of the 2 protective films 32 may be the same or different. In addition, the 2 protective films 32 may have the same retardation characteristics or may have different retardation characteristics.
As described above, at least one of the protective films 32 may have a surface treatment layer (coat layer) such as a hard coat layer, an antiglare layer, a light diffusion layer, an antireflection layer, a low refractive index layer, an antistatic layer, and an antifouling layer on its outer surface (the surface opposite to the polarizing plate 31).
The thickness of the protective film 32 includes the thickness of the surface treatment layer.
The protective film 32 may be attached to the polarizing plate 31 via an adhesive layer or an adhesive layer, for example. As the adhesive for forming the adhesive layer, an aqueous adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and an aqueous adhesive or an active energy ray-curable adhesive is preferable. As the pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer described later can be used.
Examples of the aqueous adhesive include an adhesive containing an aqueous polyvinyl alcohol resin solution, and an aqueous two-pack type urethane emulsion adhesive. Among them, an aqueous adhesive containing an aqueous solution of a polyvinyl alcohol resin is suitably used. As the polyvinyl alcohol resin, in addition to a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate, a polyvinyl alcohol copolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith, a modified polyvinyl alcohol polymer obtained by modifying a hydroxyl group portion thereof, and the like can be used. The aqueous adhesive may contain a crosslinking agent such as an aldehyde compound (glyoxal or the like), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.
When an aqueous adhesive is used, it is preferable to perform a drying step for removing water contained in the aqueous adhesive after the polarizing plate 31 and the protective film 32 are bonded. After the drying step, a curing step of curing at a temperature of 20 to 45 ℃ may be provided, for example.
The active energy ray-curable adhesive is an adhesive containing a curable compound that is cured by irradiation with an active energy ray such as ultraviolet ray, visible light, electron beam, or X-ray, and is preferably an ultraviolet ray-curable adhesive.
The curable compound may be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of the cationically polymerizable curable compound include an epoxy compound (a compound having 1 or 2 or more epoxy groups in a molecule), an oxetane compound (a compound having 1 or 2 or more oxetane rings in a molecule), and a combination thereof. Examples of the radically polymerizable curable compound include a (meth) acrylic compound (a compound having 1 or 2 or more (meth) acryloyloxy groups in the molecule), another vinyl compound having a radically polymerizable double bond, and a combination thereof. The cationically polymerizable curable compound and the radically polymerizable curable compound may be used in combination. The active energy ray-curable adhesive usually further contains a cationic polymerization initiator and/or a radical polymerization initiator for initiating a curing reaction of the curable compound.
When the polarizing plate 31 and the protective film 32 are bonded to each other, at least one of the bonding surfaces may be subjected to a surface activation treatment in order to improve the adhesion. Examples of the surface activation treatment include dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, and ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.); a wet process such as an ultrasonic treatment, a saponification treatment, and an anchor coat treatment using a solvent such as water or acetone is used. These surface activation treatments may be performed alone or in combination of 2 or more.
When the protective films 32 are bonded to both surfaces of the polarizing plate 31, the adhesives used for bonding these protective films 32 may be the same type of adhesive or different types of adhesives.
The optical laminate 40 is disposed between the polarizer 31 (linear polarizing plate 30 in the embodiment shown in fig. 1) and the image display layer 10 in the display device 100. The optical laminate 40 has a λ/2 portion 41 and a λ/4 portion 42. The lambda/2 section 41 and the lambda/4 section 42 are arranged in the order of the lambda/2 section 41 and the lambda/4 section 42 from the viewing side.
The λ/2 unit 41 has a function of giving a phase difference of λ/2 to incident light of wavelength λ.
The value of the Nz coefficient of the λ/2 portion 41 is preferably substantially 0.5. A value of Nz coefficient of approximately 0.5 means that the Nz coefficient is in the range of 0.5 ± 0.1. The Nz coefficient of the λ/2 section 41 is preferably in a range of 0.45 to 0.55. Unless otherwise stated, the slow axis of the λ/2 section 41 is parallel to nx.
The λ/4 section 42 preferably has an Nz coefficient in an appropriate range of 0.3 to 0.7, more preferably 0.4 to 0.6, of the λ/4 section 42 having a function of giving a phase difference of substantially λ/4 to the incident light of the wavelength λ. More preferably 0.45 to 0.55. Unless otherwise stated, the slow axis of the λ/4 section 42 is parallel to nx.
Fig. 2 is a schematic diagram showing the arrangement relationship of the slow axis 41a of the λ/2 section 41, the slow axis 42a of the λ/4 section 42, and the transmission axis 31a of the polarizing plate 31. As shown in fig. 2, the λ/2 section 41 and the λ/4 section 42 are arranged such that an angle θ 1 between the slow axis 41a of the λ/2 section 41 and the slow axis 42a of the λ/4 section 42 is substantially 60 °. By substantially 60 ° is meant the range 60 ° ± 5 °. The λ/2 part 41 is preferably arranged with respect to the polarizing plate 31 so that the angle formed by the slow axis 41a of the λ/2 part 41 and the transmission axis 31a of the polarizing plate 31 is substantially 15 °. By substantially 15 we mean the range 15 ° ± 5 °. In this case, the λ/4 part 42 is preferably arranged with respect to the polarizing plate 31 so that an angle θ 3 formed by the slow axis 42a of the λ/4 part 42 and the transmission axis 31a of the polarizing plate 31 is substantially 75 °. By substantially 75 is meant the range of 75 ° ± 5 °.
The λ/2 section 41 and the λ/4 section 42 each have at least 1 phase delay element (1 st phase delay element) Q. The λ/2 section 41 may have 2 phase delay elements Q and 2 phase delay elements (2 nd phase delay elements) Z. The λ/4 section 42 may have 1 phase delay element Z.
[ phase delay element Q ]
The phase retarder Q is a retardation film having inverse dispersibility and giving a phase difference of substantially λ/4 to incident light of a wavelength λ. Approximately λ/4 refers to the range of one sixth to one third of the wavelength λ. The phase delay element Q may be a λ/4 plate. The phase delay element Q may be a positive a plate. The retardation element Q may be obtained by curing a polymerizable liquid crystal compound, or may be obtained by molding a molten resin or further stretching the resin.
[ phase delay element Z ]
The phase delay element Z may be a positive C plate. The positive C-plate thickness direction delay Reth (550) satisfies equation (13).
-30nm≥Reth(550)≥-120nm···(13)
The preferable range of the Reth (550) of the phase retarder Z is preferably-100 nm or more and-40 nm or less, and more preferably-90 nm or more and-50 nm or less. The polymerizable liquid crystal compound may be obtained by curing, or may be obtained by molding or further stretching a molten resin.
When the phase retardation element Q and the phase retardation element Z are layers obtained by curing polymerizable liquid crystal, the phase retardation element Q and the phase retardation element Z are formed on an alignment film provided on a base material. The substrate may be a long substrate having a function of supporting the alignment film. The substrate can function as a releasable support and can support a phase difference film for transfer. Further, the surface preferably has a sufficient adhesive force to enable peeling. The substrate may be a resin film exemplified as a material of the protective film 32.
The thickness of the substrate is not particularly limited, and is preferably in the range of, for example, 20 μm or more and 200 μm or less. If the thickness of the base material is 20 μm or more, strength can be imparted. On the other hand, if the thickness is 200 μm or less, increase of machining chips and abrasion of the cutting blade can be suppressed when the base material is cut into a single base material.
The substrate may be subjected to various anti-blocking treatments. Examples of the anti-blocking treatment include an easy adhesion treatment, a treatment of mixing a filler or the like, and an embossing (knurling treatment). By applying such anti-blocking treatment to the base material, adhesion between the base materials when the base materials are wound up, so-called blocking, can be effectively prevented, and the optical film can be produced with high productivity.
The layer obtained by curing the polymerizable liquid crystal compound is formed on the substrate via an alignment film. That is, a substrate and an alignment film are laminated in this order, and a layer obtained by curing a polymerizable liquid crystal compound is laminated on the alignment film.
The alignment film is not limited to a vertical alignment film, and may be an alignment film in which the molecular axis of the polymerizable liquid crystal compound is aligned horizontally or an alignment film in which the molecular axis of the polymerizable liquid crystal compound is aligned obliquely. In the case of manufacturing the phase retardation element Q, a horizontal alignment film may be used, and in the case of manufacturing the phase retardation element Z, a vertical alignment film may be used.
The alignment film is preferably one having solvent resistance that is not dissolved by coating of a composition containing a polymerizable liquid crystal compound described later and heat resistance for use in heat treatment for removing the solvent and aligning the liquid crystal compound. Examples of the alignment film include an alignment film containing an alignment polymer, a photo-alignment film, and a groove alignment film in which a concave-convex pattern and a plurality of grooves are formed on the surface thereof and the grooves are aligned. The thickness of the alignment film is usually in the range of 10nm to 10000nm, preferably 10nm to 1000nm, more preferably 500nm or less, and still more preferably 10nm to 200 nm.
The resin used for the alignment film is not particularly limited as long as it is a resin used as a material of a known alignment film, and a conventionally known cured product obtained by curing a monofunctional or polyfunctional (meth) acrylate monomer with a polymerization initiator, or the like can be used. Specifically, examples of the (meth) acrylate monomer include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, and urethane acrylate. The resin may be a mixture of 1 or 2 or more of them.
The type of the polymerizable liquid crystal compound used in the present embodiment is not particularly limited, but the polymerizable liquid crystal compound can be classified into a rod-like type (rod-like liquid crystal compound) and a discotic type (discotic liquid crystal compound ) according to its shape. Further, there are a low molecular type and a high molecular type, respectively. The polymer generally refers to a molecule having a polymerization degree of 100 or more (polymer physics and phase transition kinetics, native well, 2 p., rock book store, 1992).
In the present embodiment, any polymerizable liquid crystal compound may be used. In addition, 2 or more kinds of rod-like liquid crystal compounds, 2 or more kinds of discotic liquid crystal compounds, or a mixture of rod-like liquid crystal compounds and discotic liquid crystal compounds may be used.
As the rod-like liquid crystal compound, for example, the compounds described in claim 1 of Japanese patent application laid-open No. 11-513019 or paragraphs [0026] to [0098] of Japanese patent application laid-open No. 2005-289980 can be suitably used. As the disk-shaped liquid crystal compound, for example, compounds described in paragraphs [0020] to [0067] of Japanese patent laid-open No. 2007-108732 or paragraphs [0013] to [0108] of Japanese patent laid-open No. 2010-244038 can be suitably used.
The polymerizable liquid crystal compound may be used in combination of 2 or more. In this case, at least 1 species has 2 or more polymerizable groups in the molecule. That is, the layer formed by curing the polymerizable liquid crystal compound is preferably a layer in which a liquid crystal compound having a polymerizable group is fixed by polymerization. In this case, it is no longer necessary to exhibit liquid crystallinity after the layer is formed.
The polymerizable liquid crystal compound has a polymerizable group capable of undergoing a polymerization reaction. The polymerizable group is preferably a functional group capable of addition polymerization such as a polymerizable ethylenically unsaturated group or a cyclopolymerizable group. More specifically, examples of the polymerizable group include a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, (meth) acryloyl groups are preferable. The term "meth (acryloyl group" means a concept including both a methacryloyl group and an acryloyl group.
The layer obtained by curing the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound to, for example, an alignment film. The composition may contain components other than the polymerizable liquid crystal compound. For example, the composition preferably contains a polymerization initiator. The polymerization initiator used is selected from, for example, a thermal polymerization initiator and a photopolymerization initiator depending on the form of the polymerization reaction. Examples of the photopolymerization initiator include α -carbonyl compounds, acyloin ethers, α -hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminobenzophenones, and the like. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content in the coating liquid.
The composition may contain a polymerizable monomer in terms of uniformity of the coating film and strength of the film. Examples of the polymerizable monomer include radically polymerizable and cationically polymerizable compounds. Among them, polyfunctional radical polymerizable monomers are preferable.
As the polymerizable monomer, a polymerizable monomer copolymerizable with the polymerizable liquid crystal compound is preferable. Specific examples of the polymerizable monomer include polymerizable monomers described in paragraphs [0018] to [0020] in Japanese patent laid-open publication No. 2002-296423. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, based on the total mass of the polymerizable liquid crystal compound.
The composition may contain a surfactant in terms of uniformity of the coating film and strength of the film. Examples of the surfactant include conventionally known compounds. Among them, fluorine compounds are particularly preferable. Specific examples of the surfactant include compounds described in paragraphs [0028] to [0056] in Japanese patent application laid-open No. 2001-330725 and compounds described in paragraphs [0069] to [0126] in Japanese patent application laid-open No. 2003-295212.
The composition may contain a solvent, and an organic solvent is preferably used. Examples of the organic solvent include amides (e.g., N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1, 2-dimethoxyethane). Among them, alkyl halides and ketones are preferable. In addition, 2 or more organic solvents may be used in combination.
The composition may contain various orientation agents such as a vertical orientation promoter such as a polarizing film interface-side vertical orientation agent and an air interface-side vertical orientation agent, and a horizontal orientation promoter such as a polarizing film interface-side horizontal orientation agent and an air interface-side horizontal orientation agent. The composition may further contain an adhesion improving agent, a plasticizer, a polymer, and the like in addition to the above components.
When the λ/2 unit 41 has 2 phase delay elements Q and 2 phase delay elements Z and the λ/4 unit 42 has 1 phase delay element Q and 1 phase delay element Z, the phase delay elements Q and Z may be arranged as shown in table 1.
[ TABLE 1]
Lambda/2 part 41 Lambda/4 section 42
Configuration example a Q Z Z Q Q Z
Configuration example b Q Z Z Q Z Q
Configuration example c Q Z Q Z QZ
Configuration example d Q Z Q Z Z Q
Configuration example e Z Q Z Q Z Q
Example of arrangement f Q Q Z Z Q Z
In table 1, the arrangement of the λ/2 portion 41 and the λ/4 portion 42 indicates the arrangement state of the λ/2 portion 41 and the λ/4 portion 42 in the optical layered body 40, and the λ/2 portion 41 side is the viewing side. Therefore, in each unit showing the arrangement example of the phase delay elements Q and Z in the λ/2 section 41 and the λ/4 section 42, the left side is the viewing side. Q and Z in each unit respectively represent a phase delay element Q and a phase delay element Z, and for example, the arrangement of Q and Z corresponds to the arrangement of the phase delay element Q and the phase delay element Z.
The arrangement example a shown in table 1 is the arrangement example shown in fig. 1. That is, in the λ/2 section 41, 2 phase delay elements Q and 2 phase delay elements Z are arranged in the order of the phase delay element Q, the phase delay element Z, and the phase delay element Q from the viewing side. In the λ/4 section 42, the phase delay element Q and the phase delay element Z are arranged in the order of the phase delay element Q and the phase delay element Z from the viewing side (the λ/2 section 41 side). In the configuration example a, the Rth (550nm) of the phase retardation element Z of the λ/4 section 42 is preferably-50 nm, -70nm, or-90 nm, and more preferably-70 nm.
Configuration example b is the same configuration example as configuration example a except that the arrangement of the phase delay element Q and the phase delay element Z is reversed in the λ/4 section 42.
Configuration example c is the same configuration example as configuration example a except that in the λ/2 section 41, 2 phase delay elements Q and 2 phase delay elements Z are arranged in the order of phase delay element Q, phase delay element Z, phase delay element Q, and phase delay element Z from the viewing side.
Configuration example d is the same configuration example as configuration example c except that the arrangement of the phase delay element Q and the phase delay element Z is reversed in the λ/4 section 42.
Configuration example e is the same configuration example as configuration example b (or configuration example d), except that in the λ/2 section 41, 2 phase delay elements Q and 2 phase delay elements Z are arranged in the order of phase delay element Z, phase delay element Q, phase delay element Z and phase delay element Q from the viewing side.
Configuration example f is the same configuration example as configuration example a except that in the λ/2 section 41, 2 phase delay elements Q and 2 phase delay elements Z are arranged in the order of phase delay element Q, phase delay element Z and phase delay element Z from the viewing side.
The direction of the slow axis of the phase delay element Q of the λ/2 section 41 may substantially coincide with the direction of the slow axis 41a of the λ/2 section 41. Likewise, the direction of the slow axis of the phase delay element Q of the λ/4 section 42 may substantially coincide with the direction of the slow axis 42a of the λ/4 section 42. Approximately coincident means that the directions of the 2 slow axes may deviate by about ± 5 ° (the same applies hereinafter).
The retardation element Q of the λ/2 section 41 and the λ/4 section 42 may be a laminate of a plurality of retardation films that function as the retardation element Q as a whole. The slow axis directions of the plurality of retardation films constituting the phase retardation element Q substantially coincide with the direction of the slow axis 41 a. Similarly, the retardation element Z included in the λ/2 section 41 and the λ/4 section 42 may be a laminate of a plurality of retardation films that function as the retardation element Z as a whole. The slow axis directions of the plurality of retardation films constituting the phase retardation element Z substantially coincide with the slow axis 42a direction.
The respective members (including the phase retardation element Q and the phase retardation element Z) constituting the linear polarizing plate 30, the optical laminate 40, and the display device 100 as a laminate may be laminated using an adhesive layer (not shown), for example. When the image display layer 10 includes an electrode provided in the organic EL display element, the organic EL display element and the optical layered body 40 may be layered with an adhesive layer interposed therebetween.
The pressure-sensitive adhesive layer may be composed of a pressure-sensitive adhesive composition containing a resin such as a (meth) acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin as a main component. Among them, a pressure-sensitive adhesive composition containing a (meth) acrylic resin excellent in transparency, weather resistance, heat resistance and the like as a base polymer is preferable. The adhesive composition may be an active energy ray-curable type or a thermosetting type. The thickness of the pressure-sensitive adhesive layer is usually 3 to 30 μm, preferably 3 to 25 μm.
As the (meth) acrylic resin (base polymer) that can be used in the adhesive composition, for example, a polymer or copolymer in which 1 or 2 or more kinds of (meth) acrylic acid esters such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are used as monomers is suitably used. It is preferred to copolymerize the polar monomer with the base polymer. Examples of the polar monomer include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.
The adhesive composition may comprise only the above-mentioned base polymer, but typically also contains a crosslinking agent. Examples of the crosslinking agent include a crosslinking agent which is a metal ion having a valence of 2 or more and forms a metal carboxylate salt with a carboxyl group; a crosslinking agent which is a polyamine compound and forms an amide bond with a carboxyl group; a crosslinking agent which is a polyepoxy compound, a polyol and forms an ester bond with a carboxyl group; a crosslinking agent which is a polyisocyanate compound and forms an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferable.
Elliptical polarizing plate and method for manufacturing display device
The elliptically polarizing plate 20 is manufactured by laminating an optical laminate 40 including a λ/2 section 41 and a λ/4 section 42 and a polarizer 31 via an adhesive layer. For example, as shown in fig. 1, when a linear polarizing plate 30 in which protective films 32 are laminated on both surfaces of a polarizing plate 31 is used, the linear polarizing plate 30 is obtained by manufacturing the polarizing plate 31 and laminating the protective films 32 on both surfaces of the polarizing plate 31. Then, the pressure-sensitive adhesive layer formed on the release film is laminated on the protective film 32 facing the optical laminate 40. The polarizing plate 20 is obtained by peeling the release film on the pressure-sensitive adhesive layer and bonding the polarizer 31 to the separately manufactured λ/2 section 41 and λ/4 section 42 through the exposed pressure-sensitive adhesive layer. The elliptically polarizing plate 20 is laminated on the image display layer 10 via an adhesive layer, for example, to obtain the display device 100.
The optical laminate 40 includes a lambda/2 section 41 and a lambda/4 section 42. The Nz coefficient of the lambda/2 section 41 is substantially 0.5 and the Nz coefficient of the lambda/4 section 42 is 0.3 to 0.7. When the elliptically polarizing plate 20 including such an optical layered body 40 is layered on the image display layer 10 as a light reflection layer as shown in fig. 1, good display performance can be ensured even when the elliptically polarizing plate 20 including the optical layered body 40 is visually recognized in a state in which the display device 100 is tilted in at least 2 directions orthogonal in the plane.
For example, when the display surface is rectangular when viewed from the viewing side as in a mobile terminal (for example, a smartphone), the long side direction and the short side direction of the rectangle are given as the 2 directions orthogonal to each other in the plane. Mobile terminals such as smartphones tend to be used in a portrait configuration (corresponding to a case where a screen is viewed from a long side direction) or in a landscape configuration (corresponding to a case where a screen is viewed from a short side direction). Therefore, even when the viewer obliquely views the image in at least 2 directions orthogonal to each other in the plane, the good display performance can be ensured, and thus the viewer can view the good image even if the viewer tilts the mobile terminal.
In the mode in which the λ/2 section 41 has 2 phase delay elements Q and 2 phase delay elements Z and the λ/4 section 42 has the phase delay elements Q and the phase delay elements Z, the Nz coefficient of the λ/2 section 41 and the Nz coefficient of the λ/4 section 42 can be easily realized. In such an aspect, even when the elliptically polarizing plate 20 is obliquely viewed in at least 2 directions orthogonal in the plane, it is easy to further secure a better display performance. In particular, in the arrangement example a shown in table 1, even when the viewer views the display screen obliquely in a direction other than the 2 directions orthogonal to the plane, it is easy to ensure good display performance.
Fig. 3 is a graph showing the measurement result of the chromatic dispersion of the in-plane retardation of the trial-produced elliptically polarizing plate 20. The black dots in the graph are measurement points, and the solid line is a fit based on theoretical calculations. The dotted line indicates the wavelength dispersion in the case of an ideal λ/4 plate with an in-plane retardation of λ/4 at each wavelength. The transmittance and in-plane retardation of each of the polarizing plate 31, the λ/2 portion 41, and the λ/4 portion 42 are used in the theoretical calculation. The elliptically polarizing plate 20 used for measurement has the configuration of the configuration example (a) with the λ/2 section 41 and the λ/4 section 42. The in-plane retardation of the λ/2 part 41 and the λ/4 part 42 used for the measurement with respect to a wavelength of 550nm was 288nm and 144nm, respectively. The Nz coefficients of the λ/2 part 41 and the λ/4 part 42 used for the measurement are both 0.5. In the elliptically polarizing plate used for the measurement, the angle formed by the slow axis 41a of the λ/2 portion 41 and the transmission axis 31a of the polarizer 31 was 15.4 °, and the angle formed by the slow axis 42a of the λ/4 portion 42 and the transmission axis 31a of the polarizer 31 was 75.4 °.
A delay measuring device ("KOBRA-WPR", manufactured by Oji scientific instruments) was used for the measurement.
In fig. 3, the horizontal axis represents the wavelength (nm) and the vertical axis represents the in-plane retardation (nm) of the elliptically polarizing plate manufactured in trial. The solid line in fig. 3 represents a fitted curve with respect to the measurement results (plotted points in the figure). The dotted line in fig. 3 is a straight line indicating λ/4. As shown in fig. 3, in the optical laminate 40 of the present embodiment and the elliptically polarizing plate 20 including the optical laminate 40, since a phase difference close to λ/4 can be realized over the entire visible light, an excellent viewing angle compensation function can be realized over the entire visible light.
By applying the optical laminate 40 or the elliptically polarizing plate 20 comprising the optical laminate 40 to an LCD display device, a head-mounted display device, or the like, a wide viewing angle and high contrast can be provided over the entire visible light region. Further, by applying the optical laminate 40 or the elliptical polarizing plate 20 including the optical laminate 40 to visible circularly polarized light communication, it is possible to provide a circularly polarized light source having little radiation angle dependence over the entire visible light region.
The present invention is not limited to the above embodiments, and is intended to include the scope indicated by the claims, and all modifications within the meaning and scope equivalent to the claims.
[ examples ] A method for producing a compound
The present invention will be specifically described below with reference to examples. Unless otherwise specified, "%" and "part" in the following description mean mass% and part by mass. The present invention is not limited to the following examples.
Method for measuring film thickness
The thickness of the film was measured using a contact type film thickness meter ("MH-15M", "Counter TC 101", "MS-5C", manufactured by Nikon K.K.).
Measurement method of delay
The retardation in the thickness direction of the λ/2 part and the λ/4 part and the in-plane retardation of the λ/2 part, the λ/4 part, and the elliptically polarizing plate were measured by using a retardation measuring apparatus ("KOBRA-WPR", manufactured by prince measuring instruments).
Method for measuring refractive index
The refractive index of a film, layer, or the like is measured using a spectroscopic ellipsometer ("M-2000", manufactured by j.a. woollam corporation).
Visibility correction and hue calculation method
The visibility correction monomer transmittance Ty, the monomer transmission hue a, the monomer transmission hue b, and the visibility correction polarization degree Py, and the visibility correction reflectance Ry10, the reflection hue a, which will be described later * 10. Reflection color tone b * 10. Visibility correctionThe reflectance Ry50 is calculated using the spectral spectra corresponding to each, i.e., the single spectral transmittance T, the spectral polarization degree P, the spectral reflectance R, and the color matching function, the standard light source.
The visibility correction value is obtained by dividing the tristimulus value Y of the corresponding spectroscopic spectrum by the tristimulus value Yo of the standard light source. Color tone a * 、b * Is L of the corresponding spectral spectrum * a * b * Hue in the color system. The hues a and b are hues in the Lab color system of the corresponding spectroscopic spectra.
Among the stimulus values of red light, green light, and blue light to the pyramidal cells of the eye, the value indicating the stimulus caused by green is set as the tristimulus value Y. (refer to "color engineering, Tabok-rattan-lang co-written, SENGBEI publication, pp. 106-107, 2007"). The color matching function used the international commission on illumination (CIE) recommendations (1931). The standard light source uses D65(ISO 10526: 1999/CIES 005/E-1998). The standard white surface is used as a complete reflection surface.
Method for measuring spectral polarization degree P of polarizing plate, monomer spectral transmittance T, and monomer transmission color tones a and b
The spectral transmittance in the transmission axis direction and the spectral transmittance in the absorption axis direction of the polarizing plate were measured by an ultraviolet-visible spectrophotometer ("V7100", manufactured by japan spectrochemical corporation), and the spectral polarization degree P, the monomer spectral transmittance T, the monomer transmission color tone a, and the monomer transmission color tone b were calculated.
The monomer spectral transmittance T is an average value of the transmission axis direction spectral transmittance and the absorption axis direction spectral transmittance.
The spectral polarization degree P is obtained by dividing the difference between the transmission axis direction spectral transmittance and the absorption axis direction spectral transmittance by the sum of the transmission axis direction spectral transmittance and the absorption axis direction spectral transmittance.
The transmission axis direction spectral transmittance is a transmittance for linearly polarized light at each wavelength that vibrates parallel to the polarizing plate transmission axis.
The absorption axis direction spectral transmittance is a transmittance for linearly polarized light vibrating parallel to the absorption axis of the polarizing plate at each wavelength.
The absorption axis of the polarizer coincides with the stretching direction of polyvinyl alcohol.
Measurement of reflectance and reflectance color tone
The spectral reflectance R when the elliptical polarizing plate was disposed on the light reflecting layer was measured using the SCI mode of a display measurement system ("DMS 803", manufactured by Instrument Systems corporation), and the visibility-corrected reflectance Ry and the reflection color tone a were calculated * And a reflection color tone b * 。
The visibility correction reflectance and the reflection color tone at an inclination angle θ of 10 ° (the inclination angle will be described later) are referred to as Ry10 and a, respectively * 10、b * 10. The visibility correction reflectance at the tilt angle θ of 50 ° is referred to as Ry 50.
The spectral reflectance R at the tilt angle θ of 10 ° and θ of 50 ° was measured with the reflection intensity of only the light reflecting layer without the elliptically polarizing plate being disposed as 100%. The measurement wavelength was in the range from 380nm to 780nm for each 1 nm.
The light reflection layer was obtained by peeling a cover glass and an elliptically polarizing plate from an organic EL display device (smartphone Galaxy S9 SC-02K, manufactured by Sumsung) taken out of a commercially available smartphone.
As shown in fig. 4, a direction perpendicular to a plane p (a direction of a broken line n in fig. 4) which is developed by an axis parallel to the refractive index nx and an axis parallel to the refractive index ny is set to an inclination angle θ of 0 °. The plane p corresponds to the viewing side surface of the elliptically polarizing plate. As shown in fig. 5, the direction of the in-plane angle Φ is taken as the tilt center axis. In fig. 5, this is schematically illustrated by open arrows in the case where the plane p is inclined when Φ is 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 °, and 315 °, respectively. In each experimental example described below, the spectral reflectance R was measured in 5 ° steps in the range of expression (14). Phi, which minimizes Ry50, is 90 °. In fig. 5, the position of the in-plane angle Φ of 0 ° (or 90 °) in the plane p is for convenience of illustration.
0°≤φ＜360°···(14)
Then, Ry10, a * 10、b * 10 is a face of formula (14)Average of the range of internal angles.
Definition of the normalized reflection luminance L
The normalized reflection luminance L50 was calculated using an LCD analyzer simulator ("LCD Master ver.6", manufactured by Shintec corporation) at an inclination angle θ of 50 °.
Through the calculation by the simulator, the visibility corrected reflection Luminance luminence normalized with the visibility corrected reflection ratio calculated using the spectral reflection ratio when the standard light source is incident on the standard white surface set to 1 can be obtained.
Then, the normalized reflection Luminance L of luminence is expressed in percentage, and L50 is the normalized reflection Luminance with an inclination angle θ of 50 °. The calculation of the simulator uses the transmission axis direction spectral transmittance and the absorption axis direction spectral transmittance of the polarizing plate described in the present specification measured by the ultraviolet-visible spectrophotometer, and the refractive index obtained by measuring the phase retarder Q and the phase retarder Z described in the present specification by the ellipsometer.
In the calculation, the light reflection layer was set to be a perfect mirror surface with a reflectance of 100%.
The in-plane angle Φ shown in equation (14) is calculated as a tilt center axis in 1 ° steps. Further, in each calculation example, Φ at which the normalized reflection luminance L is the minimum is set to 90 °.
In luminence obtained by the calculation of the simulator, the influence of the interface reflection occurring between the atmosphere and the outermost surface of the elliptical polarizing plate is not included in the method of the simulator described above. Therefore, there is a deviation between the visibility correction reflectance Ry as a measured value and the normalized reflected luminance L as a calculated value, which corresponds to the reflection of the atmosphere from the interface at the outermost surface of the elliptical polarizing plate. This deviation can be inferred by Fresnel (Fresnel) formula, and if the refractive index of a front panel that is generally used is set to about 1.5, the difference between the normalized reflected luminance L50 and the visibility correction reflectance Ry50 at an inclination angle of 50 ° is estimated to be about 5.9 to 6.2%. Although there is such a deviation, the correlation between the normalized reflected luminance L50 and the value of the visibility correction reflectance Ry50 is confirmed, and it is determined that the magnitude relation of the measurement value can be sufficiently estimated by calculation using a simulator.
Question mark (Experimental value: Ry50)
In the range of the in-plane angle Φ in expression (14), as shown in fig. 6, an in-plane angle region PA1, an in-plane angle region PA2, an in-plane angle region PA3, and an in-plane angle region PA4 are set. The in-plane angle region PA1, the in-plane angle region PA2, the in-plane angle region PA3, and the in-plane angle region PA4 are ranges represented by expressions (15) to (18).
In-plane angle region PA 1:
phi is more than or equal to 85 degrees and less than or equal to 95 degrees and phi is more than or equal to 265 degrees and less than or equal to 275 degrees (15)
In-plane angle region PA 2:
phi is more than or equal to 355 degrees and less than or equal to 5 degrees and phi is more than or equal to 175 degrees and less than or equal to 185 degrees (16)
In-plane angle region PA 3:
phi is more than or equal to 40 degrees and less than or equal to 50 degrees and phi is more than or equal to 220 degrees and less than or equal to 230 degrees (17)
In-plane angle region PA 4:
phi is more than or equal to 130 degrees and less than or equal to 140 degrees and phi is more than or equal to 310 degrees and less than or equal to 320 degrees (18)
In each experimental example described below, the average value is calculated for each in-plane angular region shown in fig. 6 and expressions (15) to (18) with respect to the visibility correction reflectance Ry 50. In the following description, "Ry 50 (regions PA1 to PA 4)" represents an average value of Ry50 in the in-plane angle regions PA1 to PA 4.
Question mark (Calculation value L50)
The average value of each in-plane angle region represented by expressions (15) to (18) was calculated for the normalized reflection luminance L50 in each experimental example. In the following description, "L50 (regions PA1 to PA 4)" represents an average value of L50 of the in-plane angle regions PA1 to PA 4.
For the experiment, the following preparations were performed.
[ preparation of light reflecting layer ]
The cover glass and the elliptically polarizing plate were peeled off from an organic EL display device (smartphone Galaxy S9 SC-02K, manufactured by Sumsung) taken out of a commercially available smartphone, and provided as a light reflecting layer.
[ preparation of composition for Forming horizontally oriented film ]
5 parts of a photo-alignment material (weight average molecular weight: 30000) having the following structure and 95 parts of cyclopentanone (solvent) were mixed. The resulting mixture was stirred at 80 ℃ for 1 hour, thereby obtaining a composition for forming a horizontally oriented film.
[ chemical formula 1]
Figure BDA0003534037950000261
[ preparation of composition for Forming vertical alignment film ]
SuNEVER SE610, manufactured by Nissan chemical industries, Ltd.
[ preparation of composition for Forming phase delay element Q ]
In order to form the phase retardation element Q (inverse dispersive positive a plate), the following polymerizable liquid crystal compound a and polymerizable liquid crystal compound B were used. The polymerizable liquid crystal compound a is produced by the method described in japanese patent application laid-open No. 2010-31223. The polymerizable liquid crystal compound B is produced by the method described in Japanese patent laid-open No. 2009-173893. The respective molecular structures are shown below.
[ polymerizable liquid Crystal Compound A ]
[ chemical formula 2]
Figure BDA0003534037950000262
[ polymerizable liquid Crystal Compound B ]
[ chemical formula 3]
Figure BDA0003534037950000263
The polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B were mixed at a mass ratio of 90: 10. To 100 parts of the obtained mixture were added 1.0 part of a leveling agent ("Megaface F-556", available from DIC corporation) and 6 parts of 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one ("Omnirad 369", available from IGM Resins B.V.) as a polymerization initiator. Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%, and the mixture was stirred at 80 ℃ for 1 hour to obtain a composition for forming a phase retarder Q.
[ preparation of composition for Forming phase delay element Z ]
To form the phase retardation member Z (positive C plate), a composition was prepared according to the following procedure. To 100 parts of a polymerizable liquid crystal compound ("Paliocolor LC 242", manufactured by BASF corporation), 0.1 part of F-556 as a leveling agent and 3 parts of Omnirad369 as a polymerization initiator were added. Cyclopentanone was added so that the solid content concentration became 13%, to obtain a composition for forming the phase retarder Z.
[ production of polarizing plate ]
A polyvinyl alcohol (PVA) film having an average polymerization degree of about 2400, a saponification degree of 99.9 mol% or more and a thickness of 75 μm was prepared. The PVA film was immersed in pure water at 30 ℃ and then immersed in an aqueous solution having an iodine/potassium iodide/water mass ratio of 0.02/2/100 at 30 ℃ to carry out iodine dyeing (iodine dyeing step). The PVA film subjected to the iodine dyeing step was immersed in an aqueous solution of potassium iodide/boric acid/water at a mass ratio of 12/5/100 at 56.5 ℃ to be subjected to boric acid treatment (boric acid treatment step). The PVA film subjected to the boric acid treatment step was washed with pure water at 8 ℃ and then dried at 65 ℃ to obtain a polarizing film in which iodine was adsorbed and oriented to polyvinyl alcohol. The PVA film is stretched in the iodine dyeing step and the boric acid treatment step. The total stretch ratio of the PVA film was 5.3 times. The thickness of the obtained polarizing film was 10 μm.
A polarizing film and a saponified triacetyl cellulose (TAC) film (KC 4UYTAC thickness 40 μm, manufactured by Konika Mentoda Co., Ltd.) were bonded to each other with a nip roll using a water-based adhesive. The obtained laminate was dried at 60 ℃ for 2 minutes while maintaining the tension of 430N/m, to obtain a polarizing plate having a TAC film as a protective film on one side. The water-based adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (manufactured by Kuraray, "Kuraray Poval KL 318", ltd.) and 1.5 parts of water-soluble polyamide-epoxy Resin (manufactured by tiangang chemical corporation, "Sumirez Resin 650", an aqueous solution having a solid content concentration of 30%) to 100 parts of water.
The optical properties of the obtained polarizing plate were measured. The visibility-correcting monomer transmittance Ty of the obtained polarizing plate was 41.9%, the visibility-correcting polarization degree Py was 99.962%, the monomer transmission color tone a was-1.5, and the monomer transmission color tone b was 3.6.
[ production of phase delay element Q (inverse dispersive Positive A plate) ]
A film (ZF-14-50) of cycloolefin resin (COP) manufactured by ZEON K.K. Japan was subjected to corona treatment. The corona treatment was carried out using TEC-4AX available from Ushio Motor Co. The corona treatment was carried out 1 time at a treatment speed of 10 m/min and an output of 0.78 kW. The composition for forming a horizontally oriented film was applied to a COP film by a bar coater and dried at 80 ℃ for 1 minute. The coating film was irradiated with polarized UV light (SPOT CURE SP-9, manufactured by Ushio Motor Co., Ltd.) so that the cumulative amount of light at a wavelength of 313nm became 100mJ/cm 2 In this way, polarized UV exposure is carried out at an axial angle of 45 °. The thickness of the obtained horizontal alignment film was 100 nm.
Next, the composition for forming the phase retardation element Q (reverse dispersion positive a plate) was applied to a horizontal alignment film using a bar coater, and dried at 120 ℃ for 1 minute. The coating film was irradiated with ultraviolet rays (cumulative light amount at a wavelength of 365nm under a nitrogen atmosphere: 500 mJ/cm) using a high-pressure mercury lamp ("Unicure VB-15201 BY-A", manufactured BY Ushio Motor Co., Ltd.) 2 ) Thereby forming the phase delay element Q. The film thickness of the phase retardation element Q was 2.3. mu.m.
An adhesive layer is laminated on the phase delay element Q. Films including a COP film, an alignment film, and a horizontally aligned liquid crystal cured film were bonded to glass via the adhesive layer. The COP film was peeled off to obtain a sample for measuring retardation.
As a result of measuring the in-plane retardation ReoQ (lambda) of the phase retarder Q at each wavelength,
ReoQ(450)＝121nm，
ReoQ(550)＝142nm，
ReoQ(650)＝146nm，
ReoQ(450)/ReoQ(550)＝0.85，
ReoQ(650)/ReoQ(550)＝1.03，
the phase delay element Q exhibits reverse wavelength dispersion.
The phase delay element Q is a positive A plate satisfying the relationship nx > ny ≈ nz.
In addition, as a result of measuring the thickness direction retardation RethQ (λ) at each wavelength,
RethQ(450)＝61nm，
RethQ(550)＝72nm，
RethQ(650)＝73nm。
[ production of phase delay element Z (Positive C plate) ]
The COP film was subjected to corona treatment. The conditions of the corona treatment were the same as described above. The composition for forming a vertically aligned film was applied to a COP film by a bar coater and dried at 80 ℃ for 1 minute to obtain a vertically aligned film. The thickness of the obtained vertical alignment film was 50 nm.
The composition for forming the phase retardation element Z was coated on the vertically oriented film using a bar coater and dried at 90 ℃ for 120 seconds. The coating film was irradiated with ultraviolet rays (cumulative light amount at a wavelength of 365nm under a nitrogen atmosphere: 500 mJ/cm) using a high-pressure mercury lamp ("Unicure VB-15201 BY-A", manufactured BY Ushio Motor Co., Ltd.) 2 ) Thereby forming the phase delay element Z. The film formed of the COP film, the vertical alignment film, and the phase retardation element Z was obtained by the operation as described above. The film thickness of the phase retardation element Z was 0.6. mu.m.
An adhesive layer is laminated on the phase delay element Z. The films formed of the COP film, the alignment film, and the phase retardation element Z were bonded to glass via the adhesive layer. The COP film was peeled off to obtain a sample for measuring retardation. As a result of measuring the thickness direction retardation RethZ (550) of the phase retardation element Z at a wavelength of 550nm,
RethZ(550)＝-70nm。
the phase retardation element Z is a positive C plate satisfying the relationship nx ≈ ny < nz.
[ phase retarder laminate 1]
The phase retardation element Z of the vertical alignment film and the phase retardation element Z (C plate) formed on the COP film and the phase retardation element Q of the horizontal alignment film and the phase retardation element Q (a plate) formed on the COP film are bonded via an adhesive. Then, the COP film on the phase retardation element Q side was peeled off to obtain a film in which the COP film and the phase retardation element laminate 1 were laminated in this order.
The arrangement relationship of the retardation element Q and the retardation element Z in the retardation element laminate 1 is as follows. In order to show the arrangement of the phase retardation element Q and the phase retardation element Z with respect to the COP film, the COP film is shown in parentheses in the following arrangement relationship. Therefore, the following symbols indicate that the phase delay element Z and the phase delay element Q are arranged in the order of the phase delay element Z and the phase delay element Q from the COP film side. The same reference numerals are used in some cases for the arrangement relationship between elements (or between layers).
(COP film)/Z/Q
[ phase retardation element laminate 2]
The phase retardation element Z surface of the vertical alignment film and the phase retardation element Z formed on the COP film and the phase retardation element Q of the horizontal alignment film and the phase retardation element Q formed on the COP film are bonded via an adhesive, and then the COP film on the phase retardation element Z side is peeled off to obtain a film in which the COP film and the phase retardation element laminate 2 are sequentially laminated. The arrangement relationship of the retardation element Q and the retardation element Z in the retardation element laminate 2 is as follows.
(COP film)/Q/Z
[ phase retardation element laminate 3]
A phase retardation element Q of a horizontal alignment film and a phase retardation element Q (a plate) formed on a COP film and a phase retardation element Q of a horizontal alignment film and a phase retardation element Q (a plate) formed on a COP film are bonded via an adhesive, and then the COP film on one phase retardation element Q side is peeled off to obtain a film in which a COP film and a phase retardation element laminate 3 are sequentially laminated.
The arrangement relationship of the phase delay element Q and the phase delay element Z in the phase delay element laminate 3 is as follows.
(COP film)/Q
[ phase retardation element laminate 4]
After the phase retardation element Z surface of the vertical alignment film and the phase retardation element Z (C plate) formed on the COP film and the phase retardation element Z of the vertical alignment film and the phase retardation element Z (C plate) formed on the COP film are bonded via an adhesive, the COP film on one phase retardation element Z side is peeled off to obtain a film in which the COP film and the phase retardation element laminate 4 are sequentially laminated. The arrangement relationship of the retardation element Q and the retardation element Z in the retardation element laminate 4 is as follows.
(COP film)/Z
[ phase retardation element laminate 5]
The phase retardation element Z side of the film formed of the COP film and the phase retardation element laminate 2 and the phase retardation element Z side of the film formed of the COP film and the phase retardation element laminate 4 were bonded via an adhesive layer, and then the COP film on the phase retardation element Q side was peeled off to obtain a film in which the phase retardation element laminate 5 and the COP film were laminated in this order. The arrangement relationship of the retardation element Q and the retardation element Z in the retardation element laminate 5 is as follows.
Q/Z/Z/(COP film)
[ example 1]
< lambda/2 part >
Films formed of 2 COP films and a phase retardation member laminate 2, which were cut so that the slow axes of 2 layers of phase retardation members Q were aligned when the phase retardation member Z sides were in close contact with each other, were prepared, and the phase retardation member Z sides were bonded to each other via an adhesive. Then, the COP film on the side of one phase retardation element Q was peeled off to obtain a film in which the COP film and the λ/2 section (phase retardation element Q, adhesive layer, phase retardation element Z, adhesive layer, phase retardation element Q) were laminated in this order. The λ/2 section (phase retardation element Q, adhesive layer, phase retardation element Z, adhesive layer, phase retardation element Q) means that the phase retardation element Q, adhesive layer, phase retardation element Z, adhesive layer, and phase retardation element Q are arranged in this order in the λ/2 section. The same reference numerals are sometimes used for other members (for example, λ/4 portion).
< lambda/4 part >
The phase retarder laminate 1 described above is used as the λ/4 section.
< elliptically polarizing plate >
In the polarizing plate on which the TAC film is laminated, the surface of the polarizing plate opposite to the TAC film, and the phase retardation element Q side of the film formed of the COP film and the λ/2 part are bonded via an adhesive layer, and the COP film is peeled off to obtain a laminated body. At this time, the angle formed by the transmission axis of the polarizing plate and the slow axis of the λ/2 section was 15 °. Next, the phase retardation element Q of the laminate and the phase retardation element Q of the film formed of the COP film and the λ/4 portion were bonded via an adhesive layer, and the COP film was peeled off to obtain an elliptically polarizing plate EP 1. At this time, the angle formed by the transmission axis of the polarizing plate and the slow axis of the λ/4 section was 75 °. N of lambda/2 part Z Coefficient of 0.51, N of lambda/4 part Z The coefficient was 0.51.
In the elliptically polarizing plate EP1, a polarizer, an adhesive layer, a λ/2 section (phase retardation element Q, adhesive layer, phase retardation element Z, adhesive layer, phase retardation element Q), an adhesive layer, and a λ/4 section (phase retardation element Q, adhesive layer, phase retardation element Z) were laminated in this order on a TAC film. The arrangement of the phase retarder Q and the phase retarder Z in the optical laminate formed by laminating the λ/2 section and the λ/4 section in the elliptically polarizing plate EP1 is the arrangement of the arrangement example a in table 1.
Delay of
An adhesive layer is laminated on the phase retardation element Z located on the opposite side to the TAC film in the above-described elliptically polarizing plate EP 1. An elliptically polarizing plate EP1 was attached to glass via this adhesive layer to obtain a sample for measuring retardation.
As a result of measuring the in-plane retardation Reo (. lamda.) at each wavelength,
Reo(450)＝112nm
Reo(550)＝138nm
Reo(650)＝162nm
Reo(450)/Reo(550)＝0.81
Reo(650)/Reo(550)＝1.17。
reflectance and reflection color tone at 10 ° to the tilt angle
The elliptically polarizing plate EP1 was bonded to the light reflective layer via an adhesive to obtain sample S1.
The average value of the visibility corrected reflectance and the in-plane angle of the reflected color tone at an inclination angle θ of 10 ° with respect to the sample S1 was measured, and as a result, Ry10 was 4.6%, and a * 10＝0.00、b * 10＝-0.25。
Reflectance at an angle of inclination of 50 ° (experimental value)
The average value of each in-plane angle region of the visibility corrected reflectance Ry50 when the inclination angle θ of the sample S1 was 50 ° was measured and calculated, and the result was
Ry50 (region PA1) ═ 6.0%
Ry50 (region PA2) ═ 6.2%
Ry50 (region PA3) ═ 6.3%
Ry50 (area PA4) ═ 6.3%.
Reflectance at an angle of inclination of 50 ° (calculated value)
As a calculation model of the elliptically polarizing plate EP1, a laminate having the same lamination structure as that of the elliptically polarizing plate EP1 was designed (hereinafter, referred to as "elliptically polarizing plate EP1 s"), except that the TAC film and the adhesive layer in the elliptically polarizing plate EP1 were omitted. The elliptically polarizing plate EP1s is a laminate in which a polarizing plate, a λ/2 portion, and a λ/4 portion are laminated in this order. The sections λ/2 and λ/4 have the following configurations, respectively.
Lambda/2 part: Q/Z/Z/Q
Lambda/4 part: Q/Z
The angle formed by the transmission axis of the polarizing plate and the slow axis of the λ/2 section was set to 15 °. The angle formed by the slow axis of the transmission axis lambda/4 part of the polarizing plate was set to 75 deg.. The average value of the respective in-plane angle regions of the normalized reflected luminance L50 when the tilt angle θ was 50 ° was calculated, and as a result,
l50 (region PA1) ═ 0.03%
L50 (region PA2) ═ 0.12%
L50 (region PA3) ═ 0.07%
L50 (region PA4) ═ 0.05%.
Visual confirmation of display Properties
Visual confirmation of display performance was performed in the field by 5 observers during the daytime on a sunny day. In the case of the inclination angle of 10 ° and the case of the inclination angle of 50 °, the observation is performed at each in-plane angle corresponding to the region PA1 to the region PA 4. When 4 or more of 5 persons did not feel rainbow-colored reflected light from the light reflecting layer, the evaluation was made to show good display performance in which the reflected light was well prevented. Otherwise, the display performance was evaluated to be impaired. The method of visually confirming the display performance is also the same in the case of performing in other examples and comparative examples described later.
The results of visual confirmation in the case of the inclination angle of 10 ° and the case of the inclination angle of 50 ° in example 1 are as follows.
(visual confirmation at an angle of inclination of 10 degrees)
When the external light reflection of the light reflective layer was observed from the elliptically polarizing plate EP1 side with the inclination angle θ of sample S1 being 10 °, good display performance was confirmed in which the reflected light was satisfactorily prevented.
(visual confirmation at an inclination of 50 degrees)
When the sample S1 was observed under sunlight with the external light reflection of the light reflecting layer at an inclination angle θ of 50 °, it was confirmed that the display performance was excellent in preventing the reflected light at any in-plane angle corresponding to the regions PA1 to PA 4.
Fig. 7 is a graph showing the results of example 1, and fig. 7 also shows the results of example 2 and thereafter. In fig. 7, "1", "2", "3", and "4" in the column of "phase delay element" indicate that phase delay elements corresponding to "1", "2", "3", and "4" are arranged from the viewing side. In the graph shown in fig. 7, "o" in the column of "50 ° oblique view" indicates good display performance in which reflected light is well prevented, and "x" indicates that iridescent reflected light is seen, which impairs display performance. In other words, "o" corresponds to a case where iridescent reflected light is not observed as in the evaluation of "x".
< example 2>
An elliptically polarizing plate EP2 was obtained in the same manner as in example 1, except that the thickness direction retardation RethZ (550) of the λ/4 phase retardation element Z having a wavelength of 550nm was-50 nm, and the Nz coefficient of the λ/4 part was 0.65. The elliptically polarizing plate EP2 is composed of layers of a TAC film, a polarizer, an adhesive layer, λ/2 sections (phase retardation element Q, adhesive layer, phase retardation element Z, adhesive layer, phase retardation element Q), an adhesive layer, and λ/4 sections (phase retardation element Q, adhesive layer, phase retardation element Z).
An elliptically polarizing plate EP2 was bonded to the light reflective layer via an adhesive to obtain sample S2. The average value of each in-plane angle region of the visibility corrected reflectance Ry50 when the inclination angle θ of the sample S2 was 50 ° was measured, and the result is shown in the graph of fig. 7.
As a calculation model of the elliptically polarizing plate EP2, a laminate having the same laminate structure as that of the elliptically polarizing plate EP2 was designed (hereinafter, referred to as "elliptically polarizing plate EP2 s") except that the TAC film and the adhesive layer in the elliptically polarizing plate EP2 were omitted, as in the case of example 1. The average value of each in-plane angle region of the normalized reflected luminance L50 when the tilt angle θ of the elliptically polarizing plate EP2s is 50 ° is calculated, and the result is shown in the graph of fig. 7.
When the external light reflection of the light reflecting layer was observed visually under sunlight at an inclination angle θ of 50 ° in sample S2, it was confirmed that the display performance was excellent in preventing the reflected light at any in-plane angle corresponding to the regions PA1 to PA 4.
< example 3>
An elliptically polarizing plate EP3 was obtained in the same manner as in example 1, except that the thickness direction retardation RethZ (550) of the λ/4 phase retardation element Z having a wavelength of 550nm was-90 nm, and the Nz coefficient of the λ/4 part was 0.37. The elliptically polarizing plate EP3 is composed of layers of a TAC film, a polarizer, an adhesive layer, λ/2 sections (phase retardation element Q, adhesive layer, phase retardation element Z, adhesive layer, phase retardation element Q), an adhesive layer, and λ/4 sections (phase retardation element Q, adhesive layer, phase retardation element Z).
An elliptically polarizing plate EP3 was bonded to the light reflective layer via an adhesive to obtain sample S3. The average value of each in-plane angular region of the visibility-corrected reflectance Ry50 when the inclination angle θ of the sample S3 was 50 ° was measured, and the result is shown in the graph of fig. 7.
As a calculation model of the elliptically polarizing plate EP3, a laminate having the same laminate structure as that of the elliptically polarizing plate EP3 was designed (hereinafter, referred to as "elliptically polarizing plate EP3 s") as in the case of example 1, except that the TAC film and the adhesive layer in the elliptically polarizing plate EP3 were omitted. The average value of each in-plane angle region of the normalized reflected luminance L50 when the tilt angle θ of the elliptically polarizing plate EP3s is 50 ° is calculated, and the result is shown in the graph of fig. 7.
When the sample S3 was observed under sunlight at an inclination angle θ of 50 °, it was confirmed that the light-reflecting layer reflected external light, and as a result, the light-reflecting layer exhibited good display performance in which the reflected light was satisfactorily prevented at any in-plane angle corresponding to the regions PA1 to PA 4.
< example 4>
The polarizing plate laminate structure was a polarizer, λ/2 sections (phase retardation element Q, phase retardation element Z, phase retardation element Q), and λ/4 sections (phase retardation element Z, phase retardation element Q), as an elliptical polarizing plate EP4s for calculation. The angle formed by the transmission axis of the polarizing plate and the slow axis of the λ/2 section was set to 15 °.
The angle formed by the transmission axis of the polarizing plate and the slow axis of the λ/4 section was set to 75 °.
The average value of each in-plane angle region of the normalized reflected luminance L50 when the tilt angle θ of the elliptically polarizing plate EP4s is 50 ° was calculated, and the result is as shown in the graph of fig. 7.
< example 5>
When the phase retardation element Z and the phase retardation element Q are bonded to each other, a film formed of a COP film and the phase retardation element laminate 2 and a film formed of a COP film and the phase retardation element laminate 1, which are cut so that the slow axes of the 2-layer phase retardation element Q are oriented in the same direction, are prepared, and the phase retardation element Z side of the phase retardation element laminate 2 and the phase retardation element Q side of the phase retardation element laminate 1 are bonded to each other via an adhesive. Then, the COP film on the phase retardation element Z side was peeled off, and a film in which the COP film and the λ/2 portion (phase retardation element Q, Z, Q, Z) were sequentially stacked was obtained.
An elliptically polarizing plate EP5 was obtained in the same manner as in example 1, except for the λ/2 portion.
The elliptically polarizing plate EP5 includes a TAC film, a polarizer, an adhesive layer, layers of λ/2 units (phase retardation element Q, adhesive layer, phase retardation element Z, adhesive layer, phase retardation element Q, adhesive layer, phase retardation element Z), an adhesive layer, and λ/4 units (phase retardation element Q, adhesive layer, phase retardation element Z).
An elliptically polarizing plate EP5 was bonded to the light reflective layer via an adhesive to obtain sample S5. The average value of each in-plane angular region of the visibility-corrected reflectance Ry50 when the inclination angle θ of the sample S5 was 50 ° was measured, and the result is shown in the graph of fig. 7.
When the external light reflection of the light reflecting layer is observed under sunlight at an inclination angle θ of 50 ° in sample S5, it is confirmed that the display performance is good in that the reflected light is well prevented at an in-plane angle corresponding to the region PA1 and the region PA2, but strong rainbow-colored reflected light is observed at an in-plane angle corresponding to the region PA3 and the region PA4, and the display performance is impaired.
As a calculation model of the elliptically polarizing plate EP5, a laminate having the same lamination configuration as that of the elliptically polarizing plate EP5 was designed (hereinafter, referred to as "elliptically polarizing plate EP5 s") except that the TAC film and the adhesive layer in the elliptically polarizing plate EP5 were omitted, as in the case of example 1. The average value of each in-plane angular region of the normalized reflected luminance L50 when the inclination angle θ of the elliptically polarizing plate EP5s is 50 ° was calculated, and the result is shown in the graph of fig. 7.
< example 6>
The polarizing plate laminated structure was a polarizer, λ/2 sections (phase retardation element Q, phase retardation element Z, phase retardation element Q, phase retardation element Z), and λ/4 sections (phase retardation element Z, phase retardation element Q), and was used as the elliptical polarizing plate EP6s for calculation. The transmission axis of the polarizing plate makes an angle of 15 with the slow axis of the λ/2 section. The transmission axis of the polarizer makes an angle of 75 ° with the slow axis of the λ/4 portion.
The average value of each in-plane angle region of the normalized reflected luminance L50 when the tilt angle θ of the elliptically polarizing plate EP6s is 50 ° is calculated, and the result is shown in the graph of fig. 7.
< example 7>
The polarizing plate laminate structure was a polarizer, λ/2 sections (phase retardation element Z, phase retardation element Q, phase retardation element Z, phase retardation element Q), and λ/4 sections (phase retardation element Z, phase retardation element Q), as an elliptical polarizing plate EP7s for calculation. The transmission axis of the polarizing plate makes an angle of 15 with the slow axis of the λ/2 section. The transmission axis of the polarizer makes an angle of 75 ° with the slow axis of the λ/4 portion.
The average value of each in-plane angular region of the normalized reflected luminance L50 when the inclination angle θ of the elliptically polarizing plate EP7s is 50 ° is calculated, and the result is shown in the graph of fig. 7.
< example 8>
The polarizing plate laminate structure was a polarizer, λ/2 sections (phase retardation element Q, phase retardation element Z), and λ/4 sections (phase retardation element Q, phase retardation element Z), and used as an elliptical polarizing plate EP8s for calculation. The transmission axis of the polarizer makes an angle of 15 with the slow axis of the lambda/2 section.
The transmission axis of the polarizer makes an angle of 75 with the slow axis of the λ/4 section.
The average value of each in-plane angle region of the normalized reflected luminance L50 when the tilt angle θ of the elliptically polarizing plate EP8s is 50 ° is calculated, and the result is shown in the graph of fig. 7.
< comparative example 1>
An elliptically polarizing plate EP9 was obtained in the same manner as in example 1, except that the phase retardation element laminate 3 was set to λ/2 parts, the phase retardation element Q was set to 4 parts, and the phase retardation element Q side of the film formed of the COP film and the phase retardation element laminate 3 and the phase retardation element Q side of the film formed of the COP film, the horizontal alignment film, and the phase retardation element Q were bonded via an adhesive layer.
The elliptically polarizing plate EP9 has a layer configuration of a TAC film, a polarizer, an adhesive layer, a λ/2 section (phase retardation element Q, adhesive layer, phase retardation element Q), an adhesive layer, and a λ/4 section (phase retardation element Q).
An elliptically polarizing plate EP9 was bonded to the light reflective layer via an adhesive to obtain sample S9. The average value of each in-plane angle region of the visibility corrected reflectance Ry50 when the inclination angle θ of the sample S9 was 50 ° was measured, and the result is shown in the graph of fig. 7.
When the sample S9 was observed under sunlight at an inclination angle θ of 50 °, it was confirmed that the light-reflecting layer exhibited good display performance in which the reflected light was prevented to some extent at an in-plane angle corresponding to the region PA1, but the reflected light was strongly iridescent at an in-plane angle corresponding to the region PA 2. Strong rainbow-colored reflected light was observed at an in-plane angle corresponding to the region PA3 and the region PA4, and it was confirmed that the display performance was impaired when the inclination was in three orthogonal directions.
As a calculation model of the elliptically polarizing plate EP9, a laminate having the same lamination configuration as that of the elliptically polarizing plate EP9 was designed (hereinafter, referred to as "elliptically polarizing plate EP9 s") except that the TAC film and the adhesive layer in the elliptically polarizing plate EP9 were omitted, as in the case of example 1. The average value of each in-plane angle region of the normalized reflected luminance L50 when the tilt angle θ of the elliptically polarizing plate EP9s is 50 ° is calculated, and the result is shown in the graph of fig. 7.
< comparative example 2>
An elliptically polarizing plate EP10 was obtained in the same manner as in example 1, except that the phase retardation element laminate 3 was set to λ/2, the phase retardation element laminate 1 was set to λ/4, and the phase retardation element Q side of the film formed of the COP film and the phase retardation element laminate 3 and the phase retardation element Q side of the film formed of the COP film and the phase retardation element laminate 1 were bonded to each other via an adhesive layer.
The elliptically polarizing plate EP10 has a TAC film, a polarizer, an adhesive layer, layers of λ/2 sections (phase retardation element Q, adhesive layer, phase retardation element Q), an adhesive layer, and λ/4 sections (phase retardation element Q, adhesive layer, phase retardation element Z).
An elliptically polarizing plate EP10 was bonded to the light reflective layer via an adhesive to obtain sample S10.
The average value of each in-plane angle region of the visibility corrected reflectance Ry50 when the inclination angle θ of the sample S10 was 50 ° was measured, and the result is shown in the graph of fig. 7.
When the sample S10 was observed under sunlight at an inclination angle θ of 50 °, it was confirmed that the light-reflecting layer reflected external light had good display performance in which the reflected light was well prevented at an in-plane angle corresponding to the region PA1, but the reflected light was strongly iridescent at an in-plane angle corresponding to the region PA 2. Strong rainbow-colored reflected light was observed at an in-plane angle corresponding to the region PA3 and the region PA4, and it was confirmed that the display performance was impaired when the inclination was in three orthogonal directions.
As a calculation model of the elliptically polarizing plate EP10, a laminate having the same lamination configuration as that of the elliptically polarizing plate EP10 was designed (hereinafter, referred to as "elliptically polarizing plate EP10 s") except that the TAC film and the adhesive layer in the elliptically polarizing plate EP10 were omitted, as in the case of example 1. The average value of each in-plane angle region of the normalized reflected luminance L50 when the tilt angle θ of the elliptically polarizing plate EP10s is 50 ° is calculated, and the result is shown in the graph of fig. 7.
< comparative example 3>
An elliptically polarizing plate EP11 was obtained in the same manner as in example 1, except that the phase retardation element laminate 3 was set to λ/2, the phase retardation element laminate 5 was set to λ/4, and the phase retardation element Q side of the film formed of the COP film and the phase retardation element laminate 3 and the phase retardation element Q side of the film formed of the COP film and the phase retardation element laminate 5 were bonded to each other via an adhesive layer.
The elliptically polarizing plate EP11 has a layer structure of a TAC film, a polarizer, an adhesive layer, a λ/2 section (phase retardation element Q, adhesive layer, phase retardation element Q), an adhesive layer, a λ/4 section (phase retardation element Q, adhesive layer, phase retardation element Z).
The elliptically polarizing plate EP11 was bonded to the light reflective layer via an adhesive to obtain sample S11.
The average value of each in-plane angle region of the visibility corrected reflectance Ry50 when the inclination angle θ of the sample S11 was 50 ° was measured, and the result is shown in the graph of fig. 7.
When the sample S11 was observed under sunlight at an inclination angle θ of 50 °, strong rainbow-colored reflected light was observed at any in-plane angle corresponding to the region PA1 to the region PA4, and it was confirmed that the display performance was impaired.
As a calculation model of the elliptically polarizing plate EP11, a laminate having the same lamination configuration as that of the elliptically polarizing plate EP11 was designed (hereinafter, referred to as "elliptically polarizing plate EP11 s") as in the case of example 1, except that the TAC film and the adhesive layer in the elliptically polarizing plate EP11 were omitted. The average value of each in-plane angle region of the normalized reflected luminance L50 when the tilt angle θ of the elliptically polarizing plate EP11s is 50 ° is calculated, and the result is shown in the graph of fig. 7.
< results common to examples 2 and 3, example 5, and comparative examples 1 to 3>
The in-plane retardation Reo (λ) at each wavelength of the elliptically polarizing plates EP2, EP3 (examples 2 and 3), the elliptically polarizing plate EP5 (example 5), and the elliptically polarizing plates EP9 to EP11 (comparative examples 1 to 3) was measured. Any of the results is as follows, as in the case of the elliptically polarizing plate EP1 (example 1).
Reo(450)＝112nm，
Reo(550)＝138nm，
Reo(650)＝162nm，
Reo(450)/Reo(550)＝0.81，
Reo(650)/Reo(550)＝1.17，
The visibility corrected reflectance and the reflected color tone were measured at an inclination angle θ of 10 ° for each of samples S2, S3 (examples 2 and 3), sample S5 (example 5), and samples S9 to S11 (comparative examples 1 to 3), and as a result, Ry10 was 4.6%, a, and b, as in sample S1 (example 1) * 10＝0.00、b * 10＝-0.25。
When the external light reflection of the light reflective layer was observed under sunlight at an inclination angle θ of 10 ° in each of samples S2 and S3 (examples 2 and 3), sample S5 (example 5), and samples S9 to S11 (comparative examples 1 to 3), it was confirmed that the external light reflection was excellent in preventing the reflected light, similarly to sample S1 (example 1).
[ study of results ]
N satisfying lambda/2 part 41 Z A coefficient of approximately 0.5 and N of the lambda/4 part 42 Z The coefficient is 0.3 or more and 0.7 or less. On the other hand, comparative examples 1 to 3 do not satisfy the above conditions. As shown in fig. 7, in examples 1 to 8, in the results of visual observation at an inclination angle of 50 ° (hereinafter, referred to as "results of oblique visual observation at 50 °), it was confirmed that the reflected light was favorably prevented at the in-plane angle corresponding to at least the region PA1 and the region PA2, and the favorable display performance was exhibited. In contrast, in comparative examples 1 to 3, good display performance was not confirmed in both of the regions PA1 and PA2 or in the region PA2 as a result of 50 ° oblique observation.
In the experiment, as the in-plane angle Φ, Φ at which Ry50 is the smallest (darkest) is set to 90 ° as a reference of the in-plane angle Φ. Therefore, the regions PA1 and PA2 correspond to 2 directions orthogonal to each other at 90 ° with respect to Φ as a reference, and correspond to a case where the direction of the elliptically polarizing plate applied to the display device is viewed obliquely as a vertical direction or a horizontal direction. On the other hand, in the region PA3 and the region PA4, the direction in which the elliptically polarizing plate applied to the display device is obliquely viewed corresponds to the oblique direction. Therefore, it can be understood that N satisfies the lambda/2 part 41 Z Coefficient of performanceApproximately 0.5 and N of lambda/4 part 42 Z In examples 1 to 8 in which the coefficients are set to 0.3 or more and 0.7 or less, even when the elliptically polarizing plate is viewed obliquely in at least 2 directions orthogonal in the plane, good display performance can be ensured.
In examples 1 to 3, the results of the 50 ° oblique visual observation confirmed good display performance in which reflected light was satisfactorily prevented even at in-plane angles corresponding to the regions PA1 to PA4, respectively. That is, it can be understood that in examples 1 to 3, even when the elliptically polarizing plate is tilted by placing the display device vertically, horizontally, or obliquely, respectively, good display performance can be ensured. Therefore, it can be understood that the arrangement order of the 2 phase delay elements Q and the 2 phase delay elements Z included in the λ/2 section and the arrangement order of the phase delay elements Q and the phase delay elements Z included in the λ/4 section are preferably the arrangement order adopted in embodiments 1 to 3.
In the experimental example in which any of Ry50 (regions PA1 to PA4) was 8.1% or more, it was confirmed that iridescent reflected light was strongly visually recognized in a region where a result of 8.1% or more was obtained, and the display performance in the region was impaired. Accordingly, the value of Ry50 (regions PA1 to PA4) is preferably less than 8.1%, more preferably 6.8% or less, and still more preferably 6.3% or less. From the correspondence between the value of Ry50 and L50, it is assumed that in the experimental example in which any one of L50 (regions PA1 to PA4) is 1.13% or more, iridescent reflected light is strongly visible, and display performance is impaired. The L50 (regions PA1 to PA4) is preferably less than 1.13%, more preferably 0.78% or less, and still more preferably 0.12% or less.
From the above viewpoint, it can be understood that the arrangement order of the 2 phase delay elements Q and the 2 phase delay elements Z in the λ/2 section and the arrangement order of the phase delay elements Q and the phase delay elements Z in the λ/4 section are preferably the arrangement orders adopted in embodiments 1 to 3.
As described above, in the experiment, as the in-plane angle Φ, Φ at which Ry50 is the smallest (darkest) was set to 90 °. Therefore, Ry50 of PA1 to PA4 was compared with Ry50 of the region PA1 as a reference. In this case, in example 1, Ry50 of the region PA1 was 6.0, and the regions PA2 to PA4 were also 6.2 or 6.3. That is, in example 1, Ry50 of the region PA1 to the region PA4 is smaller than 6.3, and Ry50 of the region PA2 to the region PA4 is substantially the same value as Ry50 of the region PA1 to be the reference. Therefore, in embodiment 1, substantially constant display performance can be ensured in the areas PA1 to PA 4. Therefore, the constitution of embodiment 1 can be understood as being further preferable.

Claims (6)

1. An optical laminate comprising:
a lambda/2 part having a1 st slow axis; and
a lambda/4 unit having a2 nd slow axis and laminated on the lambda/2 unit so that the 2 nd slow axis is in a range of approximately 60 DEG with respect to the 1 st slow axis,
n of the lambda/2 part Z The factor is approximately 0.5 of the total,
n of the lambda/4 part Z The coefficient is 0.3 or more and 0.7 or less.
2. The optical stack according to claim 1, wherein each of said λ/2 portion and said λ/4 portion has a1 st phase retardation element,
the 1 st phase delay element has inverse dispersion and gives a phase difference of substantially lambda/4,
the direction of the slow axis of the 1 st phase delay element included in the λ/2 section substantially coincides with the direction of the 1 st slow axis,
the direction of the slow axis of the 1 st phase delay element included in the λ/4 section substantially coincides with the direction of the 2 nd slow axis.
3. The optical stack of claim 1, wherein the λ/2 section has 2 phase 1 retarding elements and 2 phase 2 retarding elements,
the lambda/4 section has a1 st phase delay element,
the 21 st phase delay elements of the lambda/2 section and the 1 st phase delay elements of the lambda/4 section have inverse dispersibility and impart a phase difference of substantially lambda/4,
the 2 nd phase delay elements of the lambda/2 part are positive C plates,
the 21 st phase delay elements and the 2 nd phase delay elements of the λ/2 section have respective slow axis directions substantially coincident with the 1 st slow axis direction,
the direction of the slow axis of the 1 st phase delay element included in the λ/4 section substantially coincides with the direction of the 2 nd slow axis.
4. The optical stack of claim 3, wherein the 21 st phase retarding elements and the 2 nd phase retarding elements are stacked in the order of 1 st phase retarding element, 2 nd phase retarding element and 1 st phase retarding element.
5. The optical stack of claim 1, wherein the λ/2 section has 2 phase 1 retarding elements and 2 phase 2 retarding elements,
the lambda/4 section has a1 st phase delay element and a2 nd phase delay element,
the 21 st phase delay elements of the lambda/2 section and the 1 st phase delay elements of the lambda/4 section have inverse dispersibility and impart a phase difference of substantially lambda/4,
the 2 nd phase delay elements of the λ/2 section and the 2 nd phase delay elements of the λ/4 section are positive C plates,
the 21 st phase delay elements and the 21 st phase delay elements of the λ/2 section have respective slow axis directions substantially coincident with the 1 st slow axis direction,
the slow axes of the 1 st phase delay element and the 2 nd phase delay element in the λ/4 section are substantially aligned with the direction of the 2 nd slow axis,
the 21 st phase delay elements and the 2 nd phase delay elements of the λ/2 section are stacked in the order of the 1 st phase delay element, the 2 nd phase delay element, and the 1 st phase delay element,
the 1 st phase delay element and the 2 nd phase delay element of the λ/4 block are stacked in the order of the 1 st phase delay element and the 2 nd phase delay element from the λ/2 block side.
6. An elliptical polarizing plate comprising:
a polarizing plate; and
the optical laminate according to any one of claims 1 to 5, which is laminated on the polarizing plate,
the polarizing plate, the lambda/2 section and the lambda/4 section are arranged in this order.
CN202210222730.0A 2021-03-09 2022-03-07 Optical laminate and elliptically polarizing plate Pending CN115047554A (en)

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