Optical laminate

Abstract

Provided is an optical laminate having excellent optical compensation performance in the lamination direction and in the oblique direction. An optical laminate according to an embodiment of the present invention is provided with a polarizing member and a plurality of phase difference members disposed on the viewing side of the polarizing member. The ellipticity of the optical laminate measured at an elevation angle of 90 DEG and an elevation angle of 30 DEG at an azimuth angle of 0 DEG is 0.75 or more.

Description

Technical Field

[0001] The present invention relates to optical stacks. Background Art

[0002] Image display devices represented by liquid crystal display devices and electroluminescent (EL) display devices (for example, organic EL display devices, inorganic EL display devices) are rapidly becoming popular. In image display devices, in order to realize image display and improve the performance of image display, optical laminates including polarization components and phase difference components have been widely used. On the other hand, new uses of image display devices have been developed in recent years. As an example of such uses, aerial displays and the like can be cited (for example, see patent document 1). In aerial displays, the use of aerial displays that effectively utilize aerial imaging based on retro-reflection (AIRR: aeriallimaging by retro-reflection) has been explored in various situations, and it is expected to improve the conversion efficiency from incident light of the device to real images. However, even if the optical laminate including polarization components and phase difference components is applied to AIRR-type aerial displays, the optical compensation performance is not sufficient, and sometimes the optical laminate cannot effectively convert light that is obliquely incident relative to the display element. Therefore, it is difficult to produce clear aerial imaging.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-31074 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The present invention has been made to solve the above-mentioned conventional problems, and a main object of the present invention is to provide an optical layered body having excellent optical compensation performance in a stacking direction and in an oblique direction intersecting the stacking direction.

[0008] Solutions to the problem

[0009] [1] An optical layered body according to an embodiment of the present invention comprises:

[0010] polarizing member, and

[0011] A plurality of phase difference components are arranged on the visible side of the polarization component,

[0012] The ellipticity of the optical layered body measured at an azimuth angle of 0°, an elevation angle of 90°, and an elevation angle of 30° is 0.75 or more.

[0013] [2] In the optical layered body described in [1] above, the ellipticity of the optical layered body measured at an azimuth angle of 45°, an elevation angle of 90°, and an elevation angle of 30° may be 0.70 or more.

[0014] [3] In the optical layered body described in [1] or [2] above, the plurality of phase difference members may include, in order from the visible side:

[0015] a first phase difference member having a refractive index of nz>nx=ny,

[0016] A second phase difference member functioning as a λ / 4 member,

[0017] a third phase difference member having a refractive index of nz>nx≥ny, and

[0018] The fourth phase difference member has a refractive index of nx>ny≥nz.

[0019] [4] In the optical layered body described in [1] or [2] above,

[0020] The plurality of phase difference components may include, in order from the visible side:

[0021] a first phase difference member having a refractive index of nz>nx=ny,

[0022] a second phase difference member functioning as a λ / 4 member, and

[0023] a fifth phase difference member having a refractive index of nx>nz>ny,

[0024] An angle formed between the absorption axis direction of the polarization member and the slow axis direction of the fifth phase difference member may be 90°±1.5° or less.

[0025] Effects of the Invention

[0026] According to the embodiment of the present invention, an optical layered body having excellent optical compensation performance in the stacking direction and in an oblique direction can be realized. If such an optical layered body is applied to a retroreflective aerial imaging device, clear aerial imaging can be produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic cross-sectional view of an optical layered body according to one embodiment of the present invention.

[0028] Figure 2 It is a schematic cross-sectional view of an optical layered body according to another embodiment of the present invention.

[0029] Figure 3 It is used for Figure 1A schematic top view illustrating the azimuth angles involved in an optical stack.

[0030] Figure 4 It is used for Figure 1 A side schematic diagram illustrating the elevation angle involved in an optical stack.

[0031] Figure 5 It is a schematic diagram of the structure of an aerial imaging device including an optical layered body according to one embodiment of the present invention.

[0032] Explanation of symbols

[0033] 100 Optical laminate

[0034] 1. First phase difference component

[0035] 2. Second phase difference component

[0036] 3. The third phase difference component

[0037] 4 Fourth phase difference component

[0038] 5 Polarization components

[0039] 51 Polarizing film DETAILED DESCRIPTION

[0040] Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0041] (Definition of Terms and Symbols)

[0042] The definitions of terms and symbols in this specification are as follows.

[0043] (1) Refractive index (nx, ny, nz)

[0044] "nx" is the refractive index in the direction where the refractive index in the plane reaches the maximum (ie, the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (ie, the fast axis direction), and "nz" is the refractive index in the thickness direction.

[0045] (2) In-plane phase difference (Re)

[0046] "Re(λ)" is the in-plane phase difference measured at 23°C with light of wavelength λnm. For example, "Re(550)" is the in-plane phase difference measured at 23°C with light of wavelength 550nm. When the thickness of the layer (film) is d(nm), Re(λ) can be calculated by the formula: Re(λ) = (nx-ny)×d.

[0047] (3) Retardation in the thickness direction (Rth)

[0048] "Rth(λ)" is the phase difference in the thickness direction measured at 23°C with light of wavelength λnm. For example, "Rth(550)" is the phase difference in the thickness direction measured at 23°C with light of wavelength 550nm. When the thickness of the layer (film) is d(nm), Rth(λ) can be calculated by the formula: Rth(λ) = (nx-nz)×d.

[0049] (4) Nz coefficient

[0050] The Nz coefficient can be calculated by Nz=Rth / Re.

[0051] (5) Angle

[0052] In this specification, when an angle is mentioned, the angle includes both clockwise and counterclockwise angles relative to a reference direction. Therefore, for example, "45°" means ±45°.

[0053] A. Overall structure of optical laminate

[0054] Figure 1 is a schematic cross-sectional view of an optical layered body according to one embodiment of the present invention; Figure 2 It is a schematic cross-sectional view of an optical layered body according to another embodiment of the present invention.

[0055] The optical laminate 100 shown in the figure comprises: a polarizing component 5 including a polarizing film 51, and a plurality of phase difference components arranged on the visible side of the polarizing component 5. In the optical laminate 100, the ellipticity measured at an azimuth angle of 0°, an elevation angle of 90° and an elevation angle of 30° is 0.75 or more. The ellipticity measured at an azimuth angle of 0° and an elevation angle of 90° is preferably 0.80 or more, more preferably 0.85 or more, further preferably 0.88 or more, and particularly preferably 0.90 or more. The ellipticity measured at an azimuth angle of 0° and an elevation angle of 30° is preferably 0.80 or more, more preferably 0.82 or more, further preferably 0.84 or more, and particularly preferably 0.85 or more.

[0056] When the ellipticity measured at an azimuth angle of 0° at an elevation angle of 90° and an elevation angle of 30° is above the above lower limit, the optical compensation performance can be improved in the stacking direction of the optical stack and in the oblique direction intersecting the stacking direction. Therefore, if such an optical stack is applied to the aerial imaging device described later, light incident obliquely relative to the optical stack can be effectively converted, so that clear aerial imaging can be produced. The upper limit of the ellipticity measured at an azimuth angle of 0° at an elevation angle of 90° and an elevation angle of 30° is typically less than 1.00, and for example, less than 0.95.

[0057] In this specification, the "azimuth" is as follows: Figure 3The angle θ1 shown here refers to the angle θ1 formed between the reference direction and the plane direction (direction perpendicular to the stacking direction) of the optical laminate, with the absorption axis direction of the polarizing film as the reference. When the azimuth angle θ1 is 0°, the plane direction is substantially parallel to the reference direction.

[0058] In this specification, the "elevation angle" is as follows: Figure 4 As shown, it refers to the angle θ2 formed by the reference direction and the measurement direction located on the same imaginary plane as the reference direction of the optical stack. The measurement direction is typically the direction connecting the light receiving part of the ellipticity measuring device (representatively a Mueller matrix polarimeter) and an arbitrary point on the surface of the optical stack when measuring the ellipticity. When the elevation angle is 0°, the measurement direction is substantially parallel to the reference direction, and when the elevation angle is 90°, the measurement direction is substantially parallel to the stacking direction.

[0059] In this specification, "ellipticity" is an indicator of whether light (polarized light) is close to circular polarization or linear polarization, and is the ratio of the short axis radius b to the long axis radius a of elliptically polarized light (b / a). An ellipticity of 1.0 means substantially circular polarization, and an ellipticity of 0 means substantially linear polarization.

[0060] The ellipticity can be calculated, for example, by the following method.

[0061] Make each light of wavelength 450nm, 550nm and 650nm incident on the optical laminate from the polarizing component side, measure the major axis radius a and minor axis radius b of the outgoing light (elliptically polarized light) emitted after passing through multiple phase difference components at a given elevation angle and azimuth angle, and take the average value of the minor axis radius b / major axis radius a of these lights with different wavelengths as the ellipticity. It should be noted that, in more detail, the ellipticity can be calculated according to the method described in the embodiments described later.

[0062] In one embodiment, in the optical laminate 100, the ellipticity measured at an azimuth angle of 45°, at an elevation angle of 90° and at an elevation angle of 30° is 0.70 or more. The ellipticity measured at an azimuth angle of 45° and at an elevation angle of 90° is preferably 0.80 or more, more preferably 0.85 or more, further preferably 0.88 or more, and particularly preferably 0.90 or more. The ellipticity measured at an azimuth angle of 45° and at an elevation angle of 30° is preferably 0.80 or more, more preferably 0.81 or more, further preferably 0.83 or more, and particularly preferably 0.84 or more.

[0063] When the ellipticity measured at an azimuth angle of 45°, an elevation angle of 90° and an elevation angle of 30° are above the above lower limit, the optical compensation performance in the stacking direction and the oblique direction can be stably improved. The upper limit of the ellipticity measured at an azimuth angle of 45°, an elevation angle of 90° and an elevation angle of 30° is typically less than 1.00, and for example, less than 0.95.

[0064] like Figure 1 and Figure 2 As shown, the plurality of phase difference members typically include, in order from the visible side, a first phase difference member 1 having a refractive index of nz>nx=ny and a second phase difference member 2 functioning as a λ / 4 member. With such a configuration, the optical compensation performance in the stacking direction and in an oblique direction can be more stably improved.

[0065] like Figure 1 As shown, in one embodiment, the plurality of phase difference components include, in order from the visible side: the above-mentioned first phase difference component 1, the above-mentioned second phase difference component 2, the third phase difference component 3 having a refractive index of nz>nx≥ny, and the fourth phase difference component 4 having a refractive index of nx>ny≥nz.

[0066] In addition, if Figure 2 As shown, the plurality of phase difference components include, in order from the visible side: the first phase difference component 1 mentioned above, the second phase difference component 2 mentioned above, and the fifth phase difference component 50 having a refractive index of nx>nz>ny. That is, the plurality of phase difference components may include the fifth phase difference component 50 instead of the third phase difference component 3 and the fourth phase difference component 4. In this case, the angle formed by the absorption axis direction of the polarizing film 51 provided by the polarizing component 5 and the slow axis direction of the fifth phase difference component 50 is, for example, 90°±1.5° or less (i.e., 88.5° or more and 91.5° or less), preferably 90°±less than 1.0° (i.e., more than 89.0° and less than 91.0°), and more preferably 90°±0.5° or less (i.e., 89.5° or more and 90.5° or less).

[0067] According to these structures, the optical compensation performance in the stacking direction and in the oblique direction can be improved more stably.

[0068] It should be noted that in Figure 1 In the embodiment, the number of phase difference components is 4. Figure 2 In the embodiment, the number of phase difference components is 3, but the number of phase difference components is not limited thereto. In addition to the above-mentioned phase difference components, the plurality of phase difference components may further include another phase difference component.

[0069] In one embodiment, the optical laminate 100 further comprises: a substrate 6 located on the opposite side of the first phase difference member 1 from the second phase difference member 2, and an optical functional layer 7 located on the opposite side of the substrate 6 from the first phase difference member 1. By providing the optical laminate with the optical functional layer, an optical function corresponding to the optical functional layer can be imparted to the optical laminate.

[0070] In one embodiment, the optical laminate 100 further includes a first surface protection film 8 located on the opposite side of the first phase difference member 1 to the second phase difference member 2. In the example shown in the figure, the first surface protection film 8 is located on the opposite side of the substrate 6 to the first phase difference member 1.

[0071] In addition, the optical laminate 100 may further include a second surface protection film 9. The second surface protection film 9 is located on the side of the first surface protection film 8 opposite to the first phase difference member 1, and is temporarily bonded to the first surface protection film 8.

[0072] In one embodiment, the optical laminate 100 further includes an adhesive layer 20 located on the opposite side of the polarizing member 5 to the plurality of phase difference members (opposite to the visible side). Thus, the optical laminate 100 can be attached to various optical components (e.g., image display unit, retroreflective sheet) via the adhesive layer 20.

[0073] In addition, the optical laminate 100 may further include a release liner 10. The release liner 10 is located on the side of the adhesive layer 20 opposite to the polarizing element 5 and is temporarily attached to the surface of the adhesive layer 20. The release liner 10 is temporarily attached to the adhesive layer 20 until the optical laminate is attached to the optical component, and the release liner 10 is peeled off from the adhesive layer 20 when the optical laminate is attached.

[0074] Typically, the optical stack 100 is rectangular when viewed from the stacking direction. More specifically, the optical stack 100 may be rectangular with a long side of about 10 mm to 70 mm and a short side of about 10 mm to 70 mm, a long side of about 20 mm to 40 mm and a short side of about 10 mm to 30 mm, and more specifically, a long side of about 30 mm and a short side of about 20 mm.

[0075] Hereinafter, components of the optical layered body will be described.

[0076] B. Polarization Components

[0077] The polarizing component 5 is typically an absorption-type polarizing component. The polarizing component 5 includes a polarizing film 51. The polarizing component 5 may further include a protective layer. The protective layer may be provided on at least one side of the polarizing film, or may be provided on both sides of the polarizing film. In the illustrated example, the polarizing component 5 includes a protective layer 52 provided on a side of the polarizing film 51 opposite to the visible side. Typically, the protective layer 52 is bonded to the polarizing film 51 via any appropriate adhesive layer 53. As an adhesive forming the adhesive layer 53, a UV-curable adhesive may be typically cited. The thickness of the adhesive layer 53 is, for example, greater than 1.5 μm, preferably greater than 2.0 μm, for example, less than 5.0 μm, preferably less than 3.0 μm.

[0078] B-1. Polarizing film

[0079] Any appropriate absorption-type polarizing film can be used as the polarizing film 51. The polarizing film 51 typically includes a resin film containing a dichroic substance. The polarizing film 51 can be made of a single-layer resin film or a laminate of two or more layers.

[0080] In the case of a single-layer resin film, for example, a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or a partially saponified film of an ethylene-vinyl acetate copolymer can be subjected to dyeing treatment using a dichroic substance such as iodine or a dichroic dye, stretching treatment, etc., thereby obtaining an absorbing polarizing film. Among them, an absorbing polarizing film obtained by dyeing a PVA film with iodine and uniaxially stretching the film is preferred.

[0081] The dyeing using iodine can be performed, for example, by immersing the PVA film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching can be performed after the dyeing treatment or while dyeing. In addition, the dyeing can also be performed after the stretching. The PVA film can be subjected to swelling treatment, cross-linking treatment, cleaning treatment, drying treatment, etc. as needed.

[0082] As a laminate produced using the above-mentioned two or more layers, there can be cited a laminate of a resin substrate and a PVA-type resin layer (PVA-type resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-type resin layer formed by coating on the resin substrate. The absorption-type polarizing film obtained by using a laminate of a resin substrate and a PVA-type resin layer formed by coating on the resin substrate can be produced by the following method: for example, a PVA-type resin solution is applied to a resin substrate, and the PVA-type resin layer is formed on the resin substrate by drying; the laminate is stretched and dyed to make the PVA-type resin layer into an absorption-type polarizing film. In this embodiment, it is preferred to form a polyvinyl alcohol-type resin layer containing a halide and a polyvinyl alcohol-type resin on one side of the resin substrate. Stretching typically includes immersing the laminate in a boric acid aqueous solution for stretching. In addition, stretching may further include stretching the laminate in a gas atmosphere at a high temperature (for example, above 95°C) before stretching in a boric acid aqueous solution as needed. In addition, in the present embodiment, it is preferred that the laminate is subjected to a drying shrinkage treatment in which the laminate is shrunk by more than 2% in the width direction by heating while being conveyed in the length direction. Representatively, the manufacturing method of the present embodiment includes sequentially performing an auxiliary stretching treatment in a gas atmosphere, a dyeing treatment, a stretching treatment in an aqueous solution, and a drying shrinkage treatment on the laminate. By introducing the auxiliary stretching, the crystallinity of the PVA can be improved even when the PVA is coated on the thermoplastic resin, and high optical properties can be achieved. In addition, by simultaneously improving the orientation of the PVA in advance, it is possible to prevent problems such as a decrease in orientation and dissolution of the PVA when immersed in water in the subsequent dyeing process and the stretching process, and high optical properties can be achieved. In addition, when the PVA-type resin layer is immersed in a liquid, the orientation disorder of the polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to the case where the PVA-type resin layer does not contain a halide. As a result, the optical properties of the absorption-type polarizing film obtained by the treatment process of immersing the laminate in a liquid such as a dyeing treatment and a stretching treatment in an aqueous solution can be improved. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through the drying shrinkage treatment. The obtained laminate of resin substrate / absorption type polarizing film can be used directly (that is, the resin substrate can be made into a protective layer of the absorption type polarizing film), or the resin substrate can be peeled off from the laminate of resin substrate / absorption type polarizing film, and any appropriate protective layer corresponding to the purpose can be laminated on the peeled surface or on the side opposite to the peeled surface. The details of the manufacturing method of such an absorption type polarizing film are described in, for example, Japanese Patent Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated into this specification by reference.

[0083] The thickness of the polarizing film is, for example, 1 μm to 20 μm, preferably 2 μm to 15 μm, more preferably 12 μm or less, further preferably 10 μm or less, particularly preferably 8 μm or less, and particularly preferably 5 μm or less.

[0084] The polarizing film preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The orthogonal transmittance (Tc) of the polarizing film is, for example, 0.5% or less, preferably 0.1% or less, and more preferably 0.05% or less. The single transmittance (Ts) of the polarizing film is, for example, 41.0% to 46.0%, and preferably 42.0% or more. The polarization degree of the polarizing film is, for example, 97.0% to 99.997% or more, preferably 99.0% or more, and more preferably 99.9% or more.

[0085] B-2. Protective layer

[0086] The protective layer can be formed of any appropriate film that can be used as a protective layer of the polarizing film. Specific examples of the material that becomes the main component of the film include cycloolefins (COP) such as polynorbornenes, polyesters such as polyethylene terephthalate (PET), cellulose resins such as triacetate cellulose (TAC), polycarbonates (PC), (meth) acrylic acid, polyvinyl alcohol, polyamide, polyimide, polyether sulfone, polysulfone, polystyrene, polyolefin, acetate and other transparent resins. In addition, thermosetting resins or ultraviolet curing resins such as (meth) acrylic acid, carbamate, (meth) acrylic acid carbamate, epoxy, silicone, etc. can also be mentioned. It should be noted that "(meth) acrylic resin" refers to acrylic resin and / or methacrylic resin. In addition, glassy polymers such as siloxane polymers can also be mentioned. In addition, the polymer film of recording in Japanese Patent Publication No. 2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl and nitrile group in the side chain can be used, and for example: a resin composition having an alternating copolymer formed by isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be cited. This polymer film can be, for example, an extrusion molding of the above-mentioned resin composition. The material of the resin film can be used alone or in combination.

[0087] The thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and further preferably 5 μm to 150 μm.

[0088] In addition, a hard coating layer 54 may be provided on the surface of the protective layer 52 on the opposite side to the polarizing film 51 (opposite to the visible side). That is, the polarizing member 5 may include a hard coating layer 54. The hard coating layer 54 is directly formed on the surface of the protective layer 52. In this specification, "directly" means without intervening an adhesive layer (adhesive layer or adhesive layer).

[0089] The hard coating layer 54 preferably has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. The hard coating layer 54 can be formed of any appropriate resin. The hard coating layer 54 can be typically formed of an ultraviolet curable resin. Examples of ultraviolet curable resins include polyesters, acrylics, urethanes, amides, silicones, and epoxies. The thickness of the hard coating layer 54 is, for example, 0.5 μm or more, preferably 1 μm or more, and, for example, 20 μm or less, preferably 15 μm or less.

[0090] C. First phase difference component

[0091] The first phase difference member 1 is located on the opposite side of the second phase difference member 2 from the polarization member 5. The first phase difference member 1 is typically a phase difference film. The first phase difference member 1 is typically attached to the second phase difference member 2 via any appropriate adhesive layer 11. As an adhesive forming the adhesive layer 11, a UV curable adhesive can be typically cited. The thickness of the adhesive layer 11 is, for example, 1.5 μm or more, preferably 2.0 μm or more, for example, 5.0 μm or less, preferably 3.0 μm or less.

[0092] As described above, the first phase difference component 1 has a refractive index of nz>nx=ny. Sometimes a layer (film) having a refractive index of nz>nx=ny is called a "positive C plate" or the like. It should be noted that "nx=ny" includes not only the case where nx and ny are completely equal, but also the case where they are substantially equal. The in-plane phase difference Re(550) of the first phase difference component 1 can be, for example, greater than 0 nm and less than 10 nm.

[0093] The retardation Rth(550) in the thickness direction of the first phase difference member 1 is typically less than 0 nm, preferably -5 nm or less, more preferably -50 nm or less, for example -200 nm or more, preferably -150 nm or more, more preferably -110 nm or more.

[0094] The first phase difference member 1 can be formed of any appropriate material. The first phase difference member 1 is preferably formed of a film containing a liquid crystal material fixed to a homeotropic orientation. The liquid crystal material (liquid crystal compound) capable of homeotropic orientation can be a liquid crystal monomer or a liquid crystal polymer. As a specific example of the method for forming the liquid crystal compound and the optical compensation layer, the liquid crystal compound and the method for forming the optical compensation layer described in

[0020] to

[0028] of Japanese Patent Gazette No. 2002-333642 can be cited. In this case, the thickness of the first phase difference member 1 is, for example, less than 10 μm, preferably less than 8 μm, more preferably less than 5 μm, and representatively more than 0.5 μm.

[0095] D. Second phase difference component

[0096] The second phase difference member 2 Figure 1 is located between the first phase difference member 1 and the third phase difference member 3, Figure 2 The second phase difference member 2 is located between the first phase difference member 1 and the fifth phase difference member 50. The second phase difference member 2 is typically a phase difference film. The second phase difference member 2 is typically attached to the third phase difference member 3 or the fifth phase difference member 50 via any appropriate adhesive layer 21. As an adhesive forming the adhesive layer 21, for example, (meth) acrylic adhesives, urethane adhesives, silicone adhesives, rubber adhesives can be cited, and (meth) acrylic adhesives can be preferably cited. The thickness of the adhesive layer 21 is, for example, greater than 3.5 μm and less than 35 μm.

[0097] As described above, the second phase difference member 2 functions as a λ / 4 member. The second phase difference member 2 typically has a refractive index of nx>ny≥nz. It should be noted that, here, "ny=nz" includes not only the case where ny and nz are completely equal but also the case where they are substantially equal.

[0098] The in-plane phase difference Re(550) of the second phase difference member 2 is typically 100 nm to 200 nm, preferably 110 nm to 180 nm, more preferably 130 nm to 150 nm. The Nz coefficient of the second phase difference member 2 is preferably 0.9 to 2.0, more preferably 0.9 to 1.5, and further preferably 0.9 to 1.2.

[0099] The angle between the absorption axis direction of the polarizing film 51 and the slow axis direction of the second phase difference member 2 is typically 40° to 50°, preferably 42° to 48°, more preferably 44° to 46°, and particularly preferably 45°.

[0100] The second phase difference component 2 may show a reverse wavelength dispersion characteristic in which the phase difference value increases with the wavelength of the measurement light, may show a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measurement light, or may show a flat wavelength dispersion characteristic in which the phase difference value hardly changes with the wavelength of the measurement light. The second phase difference component 2 preferably shows a reverse wavelength dispersion characteristic. That is, the second phase difference component 2 preferably satisfies the relationship of Re(450)<Re(550).

[0101] As the resin constituting the second phase difference member 2, for example, polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, (meth) acrylic resins. Such resins can be used alone or in combination. The resin constituting the second phase difference member 2 preferably includes a polycarbonate resin.

[0102] The polycarbonate resin preferably contains at least one structural unit selected from the structural unit represented by the following general formula (1) and / or the structural unit represented by the following general formula (2). These structural units are structural units derived from divalent oligofluorenes, and are sometimes referred to as oligofluorene structural units hereinafter. Such polycarbonate resins and the like have positive refractive index anisotropy.

[0103] [Chemical formula 1]

[0104]

[0105] [Chemical formula 2]

[0106]

[0107] In the general formulas (1) and (2), R 1 ~R 3 Each independently represents a directly bonded, substituted or unsubstituted alkylene group having 1 to 4 carbon atoms; R 4 ~R 9 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms, a substituted sulfur atom, a substituted silicon atom, a halogen atom, a nitro group, or a cyano group; wherein R 4 ~R 9 They can be the same or different from each other, R4 ~R 9 At least two adjacent groups in the group may be bonded to each other to form a ring.

[0108] The content ratio of the oligofluorene structural unit in the polycarbonate resin is, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 18% by mass or more, for example, 40% by mass or less, preferably 35% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less. When the content ratio of the oligofluorene structural unit is above the above lower limit, the desired reverse wavelength dispersion dependence can be stably exhibited in the second phase difference component. When the content ratio of the oligofluorene structural unit is below the above upper limit, the phase difference can be stably exhibited.

[0109] The polycarbonate resin preferably contains a structural unit represented by the following structural formula (3) and / or a structural unit represented by the following structural formula (4) in addition to the oligofluorene structural unit. If the polycarbonate resin contains a structural unit represented by the following structural formula (3) and / or the following structural formula (4), the desired reverse wavelength dispersion dependence can be more stably exhibited in the second phase difference member 2.

[0110] [Chemical formula 3]

[0111]

[0112] [Chemical formula 4]

[0113]

[0114] The content ratio of the structural unit represented by the above structural formula (3) in the polycarbonate resin is, for example, 5 mass% or more, preferably 10 mass% or more, more preferably 20 mass% or more, and further preferably 25 mass% or more, for example, 90 mass% or less, preferably 70 mass% or less, and more preferably 50 mass% or less.

[0115] The content ratio of the structural unit represented by the above structural formula (4) in the polycarbonate resin is, for example, 5 mass % or more, preferably 10 mass % or more, more preferably 15 mass % or more, for example, 90 mass % or less, preferably 70 mass % or less, more preferably 50 mass % or less.

[0116] It is particularly preferred that the resin constituting the second phase difference member 2 contains a (meth)acrylic resin in addition to the polycarbonate resin.

[0117] The (meth) acrylic resin typically contains a structural unit derived from methyl methacrylate. The content ratio of the structural unit derived from methyl methacrylate in the (meth) acrylic resin is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. When the content ratio of the structural unit derived from methyl methacrylate is above the above lower limit, excellent compatibility with the polycarbonate resin can be exhibited. The content ratio of the structural unit derived from methyl methacrylate is typically 100% by mass or less.

[0118] The weight average molecular weight Mw of the (meth) acrylic resin is, for example, 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and for example, 200,000 or less, preferably 180,000 or less, more preferably 150,000 or less. It should be noted that the above-mentioned weight average molecular weight is a molecular weight in terms of polystyrene measured by GPC. If the weight average molecular weight Mw is within such a range, excellent compatibility with polycarbonate resins can be stably exhibited.

[0119] The content ratio of the (meth) acrylic resin in the resin constituting the second phase difference member 2 is, for example, 0% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, for example, 2.0% by mass or less, preferably 1.5% by mass or less, more preferably 1.0% by mass or less, further preferably 0.9% by mass or less, and particularly preferably 0.8% by mass or less. When the content ratio of the (meth) acrylic resin is within the above range, the elongation and phase difference performance can be significantly increased, and the haze can be suppressed.

[0120] Such a second phase difference member 2 is typically a stretched film of a polymer film formed of the resin constituting the above-mentioned second phase difference member, and is produced by stretching the polymer film.

[0121] The thickness of the second phase difference member 2 can be set to obtain desired optical characteristics. The thickness of the second phase difference member 2 is, for example, 15 μm or more, preferably 10 μm or more, more preferably 20 μm or more, for example, 60 μm or less, preferably 55 μm or less, and more preferably 50 μm or less.

[0122] E. The third phase difference component

[0123] like Figure 1 As shown, the third phase difference member 3 is located between the second phase difference member 2 and the fourth phase difference member 4. Typically, the third phase difference member 3 is attached to the fourth phase difference member 4 via any appropriate adhesive layer 31. The adhesive forming the adhesive layer 31 and the range of the thickness of the adhesive layer 31 are the same as those of the adhesive layer 11 described above.

[0124] As described above, the third phase difference member 3 has a refractive index of nz>nx≥ny. The third phase difference member 3 preferably has a refractive index of nz>nx>ny. A layer (film) having a refractive index of nz>nx>ny is sometimes called a "positive B plate" or the like.

[0125] The in-plane phase difference Re(550) of the third phase difference member 3 is, for example, greater than or equal to 15 nm, or preferably greater than or equal to 20 nm, and for example, less than or equal to 55 nm, or preferably less than or equal to 45 nm.

[0126] The retardation Rth(550) in the thickness direction of the third phase difference member 3 is typically 0 nm or less, preferably -20 nm or less, more preferably -60 nm or less, for example -250 nm or more, preferably -200 nm or more, more preferably -150 nm or more.

[0127] When the third phase difference member 3 has a refractive index of nz>nx>ny, the angle formed by the slow axis direction of the third phase difference member 3 and the absorption axis direction of the polarizing film 51 is representatively 80° or more and 100° or less, preferably 85° or more and 95° or less, more preferably 88° or more and 92° or less, and further preferably 89° or more and 91° or less. In addition, the slow axis direction of the third phase difference member 3 and the absorption axis direction of the polarizing film 51 may also be substantially parallel. In this case, the angle formed by the slow axis direction of the third phase difference member 3 and the absorption axis direction of the polarizing film 51 is representatively 0°±5° or less, preferably 0°±1° or less.

[0128] The third phase difference member 3 may exhibit reverse wavelength dispersion characteristics, positive wavelength dispersion characteristics, or flat wavelength dispersion characteristics. The third phase difference member 3 preferably exhibits reverse wavelength dispersion characteristics. That is, the third phase difference member 3 preferably satisfies the relationship of Re(450)<Re(550).

[0129] The third phase difference member 3 may have any appropriate structure. Specifically, the phase difference member may be a single phase difference member or a laminate of two or more identical or different phase difference members. The third phase difference member 3 is preferably a single phase difference member (phase difference film).

[0130] As the resin constituting the third phase difference component 3, for example, thermoplastic resins can be cited, and polymers showing negative birefringence and polymers showing positive birefringence can be preferably cited. Such resins can be used alone or in combination. The resin constituting the third phase difference component 3 more preferably includes a polymer showing negative birefringence. By using a polymer showing negative birefringence, a phase difference component having a refractive index ellipsoid of nz>nx>ny and excellent uniformity in the slow axis direction can be easily obtained. Here, "showing negative birefringence" means that when the polymer is oriented by stretching, the refractive index in the stretching direction becomes relatively small. In other words, the refractive index in the direction orthogonal to the stretching direction becomes larger. As a polymer showing negative birefringence, for example, polymers having chemical bonds and functional groups with large polarization anisotropy such as aromatic rings and carbonyl groups introduced into the side chains. Specifically, acrylic resins, styrene resins, maleimide resins, and fumarate resins can be cited, and styrene resins and fumarate resins can be preferably cited.

[0131] Preferred examples of the styrene-based resin constituting the third phase difference member 3 include styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-(meth)acrylate copolymers, styrene-maleimide copolymers, vinyl ester-maleimide copolymers, and olefin-maleimide copolymers.

[0132] As the fumarate-based resin constituting the third phase difference member 3 , preferably, a fumarate-(meth)acrylate copolymer is used.

[0133] These can be used alone or in combination of two or more.

[0134] In addition, as the above-mentioned polymer showing negative birefringence, a polymer having a repeating unit represented by the following general formula (I) can also be preferably used. Such a polymer can show higher negative birefringence, and has excellent heat resistance and mechanical strength. Such a polymer can be obtained by, for example, using the N substituent of the maleimide monomer as the starting material and introducing an N-phenyl substituted maleimide having a phenyl substituent at least in the ortho position.

[0135] [Chemical formula 5]

[0136]

[0137] In the above general formula (I), R 1 ~R 5 Each independently represents hydrogen, a halogen atom, a carboxylic acid, a carboxylic acid ester, a hydroxyl group, a nitro group, or a linear or branched alkyl or alkoxy group having 1 to 8 carbon atoms (wherein R 1 and R 5 are not hydrogen atoms at the same time), R 6 and R7 represents hydrogen or a linear or branched alkyl or alkoxy group having 1 to 8 carbon atoms, and n represents an integer of 2 or greater.

[0138] Such a third phase difference member 3 is typically a stretched film of a polymer film formed of the resin constituting the above-mentioned third phase difference member 3 , and can be produced by stretching the polymer film under any appropriate stretching conditions.

[0139] The thickness of the third phase difference member 3 can be set to obtain desired optical characteristics. The thickness of the third phase difference member 3 is, for example, 5 μm or more, preferably 10 μm or more, more preferably 20 μm or more, for example, 70 μm or less, preferably 60 μm or less, and more preferably 40 μm or less.

[0140] F. Fourth phase difference member 4

[0141] The fourth phase difference member 4 is typically bonded to the polarizing film 51 via any appropriate adhesive layer 41. The adhesive forming the adhesive layer 41 and the thickness range of the adhesive layer 41 are the same as those of the above-mentioned adhesive layer 11. The fourth phase difference member 4 is typically a phase difference film.

[0142] As described above, the fourth phase difference component 4 shows a refractive index of nx>ny≥nz. Sometimes a layer (film) having a refractive index of nx>ny>nz is called a "negative B plate" or the like. Sometimes a layer (film) having a refractive index of nx>ny=nz is called a "positive A plate" or the like. It should be noted that "ny=nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. The fourth phase difference component 4 preferably shows a refractive index of nx>ny>nz.

[0143] The in-plane phase difference Re (550) of the fourth phase difference member 4 is, for example, 70 nm or more, preferably 90 nm or more, and for example, 140 nm or less, preferably 130 nm or less.

[0144] The retardation Rth(550) in the thickness direction of the fourth phase difference member 4 is, for example, not less than 40 nm, preferably not less than 60 nm, and for example, not more than 120 nm, preferably not more than 100 nm.

[0145] The angle between the slow axis direction of the fourth phase difference component 4 and the absorption axis direction of the polarizing film 51 is typically 80° or more and 100° or less, preferably 85° or more and 95° or less, more preferably 88° or more and 92° or less, and further preferably 89° or more and 91° or less. In addition, the slow axis direction of the fourth phase difference component 4 and the absorption axis direction of the polarizing film 51 may also be substantially parallel. In this case, the angle between the slow axis direction of the fourth phase difference component 4 and the absorption axis direction of the polarizing film 51 is typically 0°±5° or less, preferably 0°±1° or less.

[0146] The slow axis direction of the third phase difference member 3 is preferably substantially parallel to the slow axis direction of the fourth phase difference member 4. In this case, the angle formed by the slow axis direction of the third phase difference member 3 and the slow axis direction of the fourth phase difference member 4 is typically 0°±5° or less, preferably 0°±1° or less.

[0147] The fourth phase difference member 4 may have a reverse wavelength dispersion characteristic, a positive wavelength dispersion characteristic, or a flat wavelength dispersion characteristic. The fourth phase difference member 4 preferably has a flat wavelength dispersion characteristic.

[0148] As the resin constituting the fourth phase difference member 4, for example, there can be cited: norbornene resin, polycarbonate resin, cellulose resin, polyvinyl alcohol resin, polysulfone resin. Such resins can be used alone or in combination. The resin constituting the fourth phase difference member 4 preferably includes norbornene resin and / or cellulose resin.

[0149] Typically, the fourth phase difference member 4 is a stretched film of a polymer film formed of the resin constituting the fourth phase difference member 4 described above, and can be produced by stretching the polymer film under any appropriate stretching conditions.

[0150] The thickness of the fourth phase difference member 4 can be set to obtain desired optical characteristics. The thickness of the fourth phase difference member 4 is, for example, 10 μm or more, preferably 20 μm or more, more preferably 60 μm or more, for example, 100 μm or less, preferably 90 μm or less, and further preferably 80 μm or less.

[0151] G. Fifth phase difference member

[0152] like Figure 2 As shown, the fifth phase difference member 50 is typically bonded to the polarizing film 51 via any appropriate adhesive layer 41 .

[0153] As described above, the fifth phase difference member 50 has a refractive index of nx>nz>ny. A layer (film) having a refractive index of nx>nz>ny is sometimes referred to as a "Z film" or the like.

[0154] The in-plane phase difference Re(550) of the fifth phase difference member 50 is typically greater than or equal to 210 nm and less than or equal to 360 nm, and preferably greater than or equal to 250 nm and less than or equal to 290 nm.

[0155] The Nz coefficient of the fifth phase difference member 50 is typically greater than or equal to 0.1 and less than or equal to 1.0, and preferably greater than or equal to 0.3 and less than or equal to 0.7.

[0156] The fifth phase difference member 50 may have a reverse wavelength dispersion characteristic, a positive wavelength dispersion characteristic, or a flat wavelength dispersion characteristic. The fifth phase difference member 50 preferably has a flat wavelength dispersion characteristic.

[0157] The fifth phase difference component 50 is typically a phase difference film formed by any appropriate resin capable of achieving the above-mentioned characteristics. As the resin constituting the fifth phase difference component 50, for example, polyarylate resins, polyamide resins, polyimide resins, polyester resins, polyaryletherketone resins, polyamideimide resins, polyesterimide resins, polyvinyl alcohol resins, polyfumarate resins, polyethersulfone resins, polysulfone resins, cycloolefin resins, polycarbonate resins, cellulose resins, and polyurethane resins can be cited. Such resins can be used alone or in combination.

[0158] As the resin constituting the fifth phase difference member 50, cycloolefin resins are preferred, and norbornene resins are more preferred. Specific examples of norbornene resins include "cycloolefin resins obtained by hydrogenating a ring-opening polymer of a norbornene monomer" described in Japanese Patent Application Laid-Open No. 2006-208925.

[0159] The fifth phase difference member 50 can be made as described below: for example, a high shrinkage film (for example, a polypropylene film) is laminated on both sides of a polymer film with the above-mentioned resin as the main component, and a roller stretching machine is used to heat and stretch it by a longitudinal uniaxial stretching method. The high shrinkage film is used to impart a shrinkage force in a direction orthogonal to the stretching direction during heating and stretching, thereby increasing the refractive index (nz) in the thickness direction of the fifth phase difference member 50. There is no particular limitation on the method of laminating a high shrinkage film on both sides of the above-mentioned polymer film, and a method of bonding an acrylic adhesive layer with an acrylic polymer as the base polymer between the above-mentioned polymer film and the above-mentioned high shrinkage film can be cited.

[0160] The thickness of the fifth phase difference member 50 is typically 20 μm or more, preferably 30 μm or more, more preferably 40 μm or more, and is typically 200 μm or less, preferably 150 μm or less.

[0161] H. Base material

[0162] The substrate 6 is a functional layer forming substrate for forming the optical functional layer 7, and is located on the opposite side (visible side) of the first phase difference member 1 to the second phase difference member 2. Typically, the substrate 6 is attached to the first phase difference member 1 via any appropriate adhesive layer 61. The adhesive forming the adhesive layer 61 and the range of the thickness of the adhesive layer 61 are the same as those of the above-mentioned adhesive layer 21.

[0163] The substrate 6 is formed of any appropriate resin film. As the resin constituting the resin film, for example, polyester resins such as polyethylene terephthalate (PET), cycloolefin resins such as norbornene resins, resins (COC) obtained by addition polymerization of cycloolefins (e.g., norbornene) and α-olefins (e.g., ethylene), cellulose resins such as triacetyl cellulose (TAC), and (meth) acrylic resins can be cited. Such resins can be used alone or in combination. The resin constituting the substrate 6 preferably includes a (meth) acrylic resin, and more preferably includes a (meth) acrylic resin having a glutarimide structure.

[0164] The thickness of the substrate 6 can be appropriately set according to the purpose. The thickness of the substrate 6 is, for example, 20 μm or more, preferably 50 μm or more, more preferably 70 μm or more, for example, 200 μm or less, preferably 150 μm or less, more preferably 90 μm or less.

[0165] I. Optical Functional Layer

[0166] Typically, the optical functional layer 7 is formed directly on the surface of the substrate 6 opposite to the first phase difference member 1 (the surface on the visible side). Examples of the optical functional layer 7 include a hard coat layer, an anti-reflection layer, an anti-adhesion layer, and an anti-glare layer. In the example shown in the figure, the optical functional layer 7 is an anti-reflection layer 7a.

[0167] The antireflection layer 7a is provided to prevent reflection of external light (for example, fluorescent light) or the like.

[0168] Any appropriate structure can be adopted as the antireflection layer 7a. Representative structures of the antireflection layer 7a include: (1) a single layer of a low refractive index layer having an optical film thickness of 120 nm to 140 nm and a refractive index of about 1.35 to 1.55; (2) a laminate having a medium refractive index layer, a high refractive index layer, and a low refractive index layer in order from the substrate 6; (3) a laminate having a plurality of layers alternating high refractive index layers and low refractive index layers.

[0169] Examples of materials that can form the low refractive index layer include silicon oxide (SiO 2 ), magnesium fluoride (MgF 2The refractive index of the low refractive index layer is typically about 1.35 to 1.55. Examples of materials that can form the high refractive index layer include titanium oxide (TiO 2 ), niobium oxide (Nb 2 O 3 or Nb 2 O 5 ), tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), ZrO 2 -TiO 2 The refractive index of the high refractive index layer is typically about 1.60 to 2.20. Examples of materials that can form the medium refractive index layer include titanium oxide (TiO 2 ), a mixture of a material that can form a low refractive index layer and a material that can form a high refractive index layer (for example, a mixture of titanium oxide and silicon oxide). The refractive index of the medium refractive index layer is typically about 1.50 to 1.85. The thickness of the low refractive index layer, the medium refractive index layer and the high refractive index layer can be set in a manner that can achieve an appropriate optical film thickness corresponding to the layer structure of the anti-reflection layer, the desired anti-reflection performance, etc.

[0170] The thickness of the antireflection layer 7a is, for example, approximately 20 nm to 300 nm.

[0171] The difference between the maximum reflectivity and the minimum reflectivity of the antireflection layer 7a in the wavelength range of 400nm to 700nm is preferably 2.0% or less, more preferably 1.9% or less, and further preferably 1.8% or less. If the difference between the maximum reflectivity and the minimum reflectivity is within such a range, coloration of reflected light can be well prevented.

[0172] J.1st surface protection film

[0173] In the example shown in the figure, the first surface protection film 8 is located on the opposite side (visible side) of the substrate 6 to the first phase difference member 1, and is attached to the optical functional layer 7 (more specifically, the anti-reflection layer 7a) via the adhesive layer 82. The first surface protection film 8 may be a material that is temporarily attached during the conveying process of the optical laminate and peeled off before the use of the optical laminate (used as a process material), or may be a material that is directly used while being attached to the surface of the optical laminate (for the purpose of permanent bonding).

[0174] The first surface protection film 8 includes a film base material 81 and an adhesive layer 82 laminated on the film base material 81 .

[0175] K. Second surface protection film

[0176] The second surface protection film 9 is a process material which is temporarily attached during the conveyance process of the optical layered body and is peeled off from the first surface protection film 8 before the foreign matter inspection of the optical layered body. The second surface protection film 9 is attached to the film base material 81 of the first surface protection film 8 .

[0177] L. Adhesive layer

[0178] In the example shown in the figure, the adhesive layer 20 is located on the side of the protective layer 52 opposite to the polarizing film 51, and is laminated on the hard coat layer 54. The adhesive forming the adhesive layer 20 is the same as that of the adhesive layer 21 described above.

[0179] The thickness of the adhesive layer 20 is typically 1 μm or more, preferably 5 μm or more, more preferably 12 μm or more, and is typically 60 μm or less, preferably 30 μm or less, more preferably 23 μm or less.

[0180] M. Release liner

[0181] The release liner 10 is formed of any appropriate resin film. Specific examples of the material that is the main component of the resin film include polyethylene terephthalate (PET), polyethylene, and polypropylene. The materials of the resin film can be used alone or in combination. The release liner 10 can be transparent or opaque.

[0182] A release layer may also be provided on the contact surface of the release liner 10 with the adhesive layer 20. Examples of release agents for forming the release layer include silicone release agents, fluorine release agents, and long-chain alkyl acrylate release agents. The release agents may be used alone or in combination. The thickness of the release layer is typically 50 nm or more and 400 nm or less.

[0183] The thickness of the release liner 10 is typically 5 μm or more, preferably 20 μm or more, and typically 60 μm or less, preferably 45 μm or less. When a release treatment layer is provided, the thickness of the release liner includes the thickness of the release treatment layer.

[0184] N. Image display device

[0185] The optical laminate described in the above-mentioned items A to M can be applied to an image display device. In more detail, after the second surface protective film 9 is peeled off from the first surface protective film 8 and the release liner 10 is peeled off from the adhesive layer 20, the optical laminate is adhered to the image display element (image display unit) via the adhesive layer 20 and applied to the image display device. Therefore, one embodiment of the present invention also includes an image display device using such an optical laminate. As representative examples of image display devices, liquid crystal display devices and organic EL display devices can be cited. The image display device of an embodiment of the present invention is representatively equipped with the optical laminate described in the above-mentioned items A to M on its visible side. The image display device includes an image display panel. The image display panel includes an image display element (image display unit). It should be noted that the image display device is sometimes referred to as an optical display device, the image display panel is sometimes referred to as an optical display panel, and the image display unit is sometimes referred to as an optical display unit.

[0186] In one embodiment, the optical laminate is applied to an image display device in such a manner that its lamination direction is substantially parallel to the thickness direction of the image display panel, thereby stably providing the image display device with excellent optical compensation performance in the front direction and in an oblique direction intersecting the front direction.

[0187] In one embodiment, the optical layered body can be suitably applied to a retroreflective aerial imaging device (AIRR type aerial display). That is, the optical layered body 100 is preferably an optical layered body for a retroreflective aerial imaging device.

[0188] like Figure 5 As shown, the retroreflective aerial imaging device 102 (hereinafter referred to as the aerial imaging device 102) includes a display element 25, the above-mentioned optical stack 100, a beam splitter 26, a retroreflective sheet 27, and a λ / 4 phase difference plate 28. In the example shown in the figure, the display element 25, the beam splitter 26, and the retroreflective sheet 27 are arranged in a substantially triangular shape when viewed from the side.

[0189] The display element 25 has a display surface for displaying an image. Examples of the display element 25 include a liquid crystal display and an organic EL display.

[0190] The optical laminate 100 is provided between the display element 25 and the beam splitter 26. Typically, the optical laminate 100 is attached to the display surface of the display element 25. More specifically, the second surface protection film 9 is peeled off from the first surface protection film 8, the release liner 10 is peeled off from the adhesive layer 20, and then the optical laminate is attached to the display element 25 through the adhesive layer 20. Light corresponding to the image displayed by the display element 25 is incident on the optical laminate 100. The optical laminate 100 converts the light (random light) of the display element 25 incident from all directions into circularly polarized light of the first rotation direction.

[0191] In a state where the optical stack is applied to an aerial imaging device, representatively, the stacking direction of the optical stack 100 is substantially parallel to a direction orthogonal to the display surface. In the optical stack 100, a plurality of phase difference components are located on the opposite side of the polarization component 5 from the display element 25. In the case where the plurality of phase difference components include a first phase difference component 1, a second phase difference component 2, a third phase difference component 3, and a fourth phase difference component 4, the first phase difference component 1, the second phase difference component 2, the third phase difference component 3, and the fourth phase difference component 4 are sequentially arranged from the beam splitter 26 side. In the case where the plurality of phase difference components include a first phase difference component 1, a second phase difference component 2, and a fifth phase difference component 50, the first phase difference component 1, the second phase difference component 2, and the fifth phase difference component 50 are sequentially arranged from the beam splitter 26 side.

[0192] The beam splitter 26 is a circularly polarized light beam splitter, which selectively reflects circularly polarized light in a first rotation direction and selectively transmits circularly polarized light in a second rotation direction opposite to the first rotation direction. The beam splitter 26 is made of, for example, cholesteric liquid crystal. The angle between the beam splitter 26 and the display element 25 is typically within 45°±5°.

[0193] The retroreflective sheet 27 can reflect the light reflected by the beam splitter 26 toward the beam splitter 26 (reflect the light from the beam splitter in a direction opposite to the incident direction). As the retroreflective sheet 27, any appropriate structure can be adopted. As the retroreflective sheet, for example, a bead type and a prism type can be cited. The angle between the retroreflective sheet 27 and the display element 25 is typically within 90°±5°.

[0194] The λ / 4 phase difference plate 28 is arranged between the retroreflective sheet 27 and the beam splitter 26. The λ / 4 phase difference plate 28 is typically provided on the surface of the retroreflective sheet 27 on the beam splitter side. The λ / 4 phase difference plate 28 typically has a refractive index of nx>ny≥nz. It should be noted that here, "ny=nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. The in-plane phase difference Re(550) of the λ / 4 phase difference plate 28 is, for example, 100nm to 200nm, preferably 130nm to 150nm.

[0195] The thickness of the λ / 4 phase difference plate 28 is set so as to have an appropriate function as a λ / 4 wave plate. The thickness of the λ / 4 phase difference plate 28 is, for example, 20 to 100 μm, preferably 20 to 60 μm, and more preferably 30 to 50 μm.

[0196] Next, the formation of an aerial image in the aerial imaging device 102 will be described.

[0197] In the aerial imaging device 102 of the example shown in the figure, first, light corresponding to the image displayed by the display element 25 is incident on the optical stack 100. The optical stack 100 converts the incident light (random light) into circularly polarized light in the first rotation direction and emits it. Since the ellipticity is greater than the above lower limit, the optical stack 100 can effectively convert light incident along the stacking direction and light incident along the oblique direction intersecting the stacking direction.

[0198] Then, the beam splitter 26 reflects the circularly polarized light of the first rotation direction from the optical stack 100 toward the retroreflective sheet 27. The circularly polarized light of the first rotation direction after being reflected by the beam splitter 26 passes through the λ / 4 phase difference plate 28 before reaching the retroreflective sheet 27 and after being retroreflected by the retroreflective sheet 27. As a result, the rotation direction of the circularly polarized light becomes the opposite direction. In other words, the circularly polarized light of the first rotation direction becomes the circularly polarized light of the second rotation direction. Then, the circularly polarized light of the second rotation direction passes through the beam splitter 26 and is imaged at a position symmetrical to the beam splitter 26 and the display element 25. As a result, a clear aerial image I is formed.

[0199] Example

[0200] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. It should be noted that the measuring methods of various properties are as follows.

[0201] (1) Determination of phase difference

[0202] The phase difference of each of the first to fifth phase difference members used in Examples and Comparative Examples was automatically measured using KOBRA-WPR manufactured by Oji Scientific Instruments. The measurement wavelength was 550 nm and the measurement temperature was 23°C.

[0203] (2) Determination of ellipticity

[0204] The ellipticity of the optical laminate obtained in the embodiment and the comparative example was measured using a high-speed / high-precision Mueller matrix polarimeter (manufactured by Axometrics, AxoScan). In more detail, the optical laminate was placed in the above-mentioned polarimeter, and light of wavelengths of 450nm, 550nm, and 650nm was incident from the polarization component side at 23°C, and the light was emitted from the first phase difference component side, and the short-axis radius b / major axis radius a of the emitted light at the azimuth and elevation angles shown in Table 1 was measured, and the average value of the short-axis radius b / major axis radius a under the above three wavelengths of light was shown in Table 1 as the ellipticity.

[0205] [Production of Polarization Component]

[0206] <Production Example 1>

[0207] As the thermoplastic resin substrate, a long amorphous isophthalic acid copolymer polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used, and one surface of the resin substrate was subjected to a corona treatment.

[0208] To 100 parts by mass of a PVA-based resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a ratio of 9:1, 13 parts by mass of potassium iodide was added, and the resulting mixture was dissolved in water to prepare a PVA aqueous solution (coating solution).

[0209] The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C., thereby forming a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.

[0210] The obtained laminate was uniaxially stretched to 2.4 times in the longitudinal direction (length direction) in an oven at 130° C. (auxiliary stretching treatment in an atmosphere).

[0211] Next, the laminate was immersed in an insolubilization bath (boric acid aqueous solution obtained by blending 4 parts by mass of boric acid with respect to 100 parts by mass of water) at a liquid temperature of 40° C. for 30 seconds (insolubilization treatment).

[0212] Next, the film was immersed in a dyeing bath (an iodine aqueous solution obtained by combining iodine and potassium iodide in a weight ratio of 1:7 relative to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the monomer transmittance (Ts) of the final polarizing film reached the desired value (dyeing treatment).

[0213] Next, the sample was immersed in a crosslinking bath (boric acid aqueous solution containing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid per 100 parts by mass of water) at a liquid temperature of 40° C. for 30 seconds (crosslinking treatment).

[0214] Then, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%) at a liquid temperature of 70°C and uniaxially stretched (stretching treatment in aqueous solution) in the longitudinal direction (length direction) between rollers with different circumferential speeds so that the total stretching ratio reached 5.5 times.

[0215] Then, the laminated body was immersed in a cleaning bath (an aqueous solution containing 4 parts by mass of potassium iodide per 100 parts by mass of water) at a liquid temperature of 20° C. (cleaning treatment).

[0216] Thereafter, the film was dried in an oven maintained at about 90° C. and brought into contact with a SUS heating roll maintained at a surface temperature of about 75° C. (drying shrinkage treatment).

[0217] In this manner, a polarizing film having a thickness of about 5 μm was formed on the resin substrate, thereby obtaining a laminate having a structure of resin substrate / polarizing film.

[0218] A cellulose resin film (thickness: 32 μm) provided with a hard coat layer was attached as a protective layer to the polarizing film surface (the side opposite to the resin substrate) of the obtained laminate via an ultraviolet curable adhesive layer. Next, the resin substrate was peeled off to obtain a polarizing member having a protective layer / polarizing film structure.

[0219] [Preparation of the First Phase Difference Member (Positive C Plate) Having a Refractive Index of nz>nx=ny]

[0220] <Production Example 2>

[0221] A liquid crystal coating liquid was prepared by dissolving 20 parts by mass of a side chain liquid crystal polymer represented by the following chemical formula (II) (the numbers 65 and 35 in the formula represent the molar % of the monomer unit; for convenience, it is expressed as a block polymer with a weight average molecular weight of 5000), 80 parts by mass of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242), and 5 parts by mass of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd.: trade name IRGACURE 907) in 200 parts by mass of cyclopentanone.

[0222] [Chemical formula 6]

[0223]

[0224] Then, the coating liquid was applied to a substrate film (norbornene resin film: manufactured by Zeon Corporation of Japan, trade name "ZEONEX") by a wire bar coater, and then heated and dried at 80°C for 4 minutes to align the liquid crystal. The liquid crystal layer was irradiated with ultraviolet rays to cure the liquid crystal layer, thereby forming a first phase difference member (first phase difference film) with a thickness of 4 μm on the substrate.

[0225] The first phase difference member thus obtained has a refractive index of nz>nx=ny. Table 1 shows the phase difference Rth(550) in the thickness direction of the first phase difference member (positive C plate).

[0226] [Production of the Second Phase Difference Member Functioning as a λ / 4 Wave Plate]

[0227] <Production Example 3>

[0228] In a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100° C., 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19×10 mol of calcium acetate monohydrate as a catalyst were added. -2 Parts by mass (6.78×10-5mol). After the reactor was replaced with nitrogen under reduced pressure, it was heated by a heat medium and stirring was started when the internal temperature reached 100°C. 40 minutes after the start of heating, the internal temperature reached 220°C, and the pressure was reduced while controlling to maintain the temperature, so that it reached 13.3kPa 90 minutes after reaching 220°C. The phenol vapor produced as a by-product during the polymerization reaction was introduced into a 100°C reflux condenser, so that a certain amount of monomer components contained in the phenol vapor returned to the reactor, and the uncondensed phenol vapor was introduced into a 45°C condenser for recovery. After nitrogen was introduced into the first reactor and temporarily restored to atmospheric pressure, the reaction liquid after oligomerization in the first reactor was transferred to the second reactor. Next, the heating and pressure reduction in the second reactor were started, so that it reached an internal temperature of 240°C and a pressure of 0.2kPa in 50 minutes. Then, the polymerization was carried out until the given stirring power was reached. When the predetermined power was reached, nitrogen gas was introduced into the reactor to restore the pressure, and the produced polyester carbonate resin was extruded into water, and the strands were cut to obtain pellets.

[0229] The obtained polyester carbonate resin (pellets) was vacuum dried at 80°C for 5 hours, and then stretched along the width direction of the roller at a stretching temperature of 150°C using a film-making device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200 mm, setting temperature: 250°C), a cold hard rolling roller (setting temperature: 120-130°C) and a winder to obtain a second phase difference component (second phase difference film) with a thickness of 47 μm as shown in Table 1.

[0230] The Re(550) of the second phase difference member obtained in this manner was 147 nm, and it could function as a λ / 4 member.

[0231] [Production of the Third Phase Difference Member (Positive B Plate) Having a Refractive Index of nz>nx>ny]

[0232] <Production Example 4>

[0233] Hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metolose 60SH-50) 48 parts by mass, distilled water 15601 parts by mass, diisopropyl fumarate 8161 parts by mass, 3-ethyl-3-oxetanylmethyl acrylate 240 parts by mass, and tert-butyl peroxypivalate 45 parts by mass as a polymerization initiator were added, and nitrogen bubbling was performed for 1 hour, and then the mixture was kept at 49° C. for 24 hours while stirring, thereby performing free radical suspension polymerization. Then, the mixture was cooled to room temperature, and the suspension containing the generated polymer particles was centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure.

[0234] The obtained fumarate resin was dissolved in a toluene / methyl ethyl ketone mixed solution (toluene / methyl ethyl ketone 50% by mass / 50% by mass) to prepare a 20% by mass solution. Furthermore, 5 parts by mass of tributyl trimellitate as a plasticizer was added to 100 parts by mass of the fumarate resin to prepare a dope.

[0235] A biaxially stretched film (75 μm thick, 1350 mm wide) of polyester (polyethylene terephthalate / ethylene isophthalate copolymer) was used as a support film, and the prepared dope was formed into a film having an arbitrary thickness and then heated and dried.

[0236] The above-mentioned laminate was placed in the delivery section of the stretching device, and while the laminate was delivered and transported to the downstream side, the stretching ratio and the stretching temperature were adjusted to achieve the phase difference value shown in Table 1, and free-end uniaxial stretching was performed in the stretching furnace. The support was peeled off from the stretched laminate to obtain a third phase difference member (third phase difference film).

[0237] The third retardation member (third retardation film) obtained in this manner has a refractive index of nz>nx>ny. Table 1 shows the in-plane retardation Re(550) and the retardation Rth(550) in the thickness direction of the third retardation member.

[0238] <Production Examples 5 to 9>

[0239] Except having changed the stretching ratio so that the phase difference value shown in Table 1 might be achieved, it carried out similarly to Production Example 4, and obtained the 3rd phase difference member (3rd phase difference film) with a thickness of 5 micrometers described in Table 1.

[0240] [Fabrication of the Fourth Phase Difference Member (Negative B Plate) Having a Refractive Index of nx>ny>nz]

[0241] <Production Example 10>

[0242] A long norbornene resin film (manufactured by Zeon Co., Ltd., trade name Zeonor, thickness 40 μm, photoelastic coefficient 3.10×10 -12 m 2 / N), the stretching ratio and the drying temperature were adjusted so as to achieve the phase difference values ​​shown in Table 1, and fixed-end transverse stretching was performed to prepare a fourth phase difference member (fourth phase difference film) having a thickness of 18 μm.

[0243] The fourth phase difference member thus obtained has a refractive index of nx>ny>nz. Table 1 shows the in-plane phase difference Re(550) and the phase difference Rth(550) in the thickness direction of the fourth phase difference member.

[0244] <Production Example 11>

[0245] The fourth phase difference member described in Table 1 was obtained in the same manner as in Production Example 10 except that the stretching ratio and the drying temperature were changed so as to achieve the phase difference value shown in Table 1.

[0246] [Production of the Fifth Phase Difference Member (Z Film) Having a Refractive Index of nx>nz>ny]

[0247] <Production Example 12>

[0248] A shrinkable film (Torayfan BO2873, manufactured by Tosoh Corporation) with a thickness of 60 μm was attached to one side of a norbornene resin film (Zeonor ZF-14-100, manufactured by Optes Co., Ltd.) with a thickness of 130 μm via an acrylic adhesive layer (thickness 20 μm). Then, the film was stretched to 1.3 times in an air circulation oven at 146°C, thereby obtaining a laminate having a fifth phase difference member (fifth phase difference film) formed on the shrinkable film. Next, the fifth phase difference member was peeled off from the shrinkable film.

[0249] The fifth phase difference member thus obtained has a refractive index of nx>nz>ny. Table 1 shows the in-plane phase difference Re(550) and Nz coefficient of the fifth phase difference member.

[0250] <<Examples 1 to 7>>

[0251] As shown in Table 1, the first phase difference component of Manufacturing Example 2, the second phase difference component of Manufacturing Example 3, the third phase difference component of any of Manufacturing Examples 4 to 9, the fourth phase difference component of Manufacturing Example 10 or 11, and the polarization component (polarization film / protective layer) of Manufacturing Example 1 are stacked in sequence. The stacking is performed in such a way that the angle between the absorption axis direction of the polarizer and the slow axis direction of the phase difference component (each of the first phase difference component to the fourth phase difference component) reaches the value of Table 1. In addition, the first phase difference component and the second phase difference component are bonded together via an ultraviolet curing adhesive layer (thickness 1μm). The second phase difference component and the third phase difference component are bonded together via a (meth) acrylic adhesive layer (thickness 23μm). The third phase difference component and the fourth phase difference component are bonded together via an ultraviolet curing adhesive layer (thickness 1μm). The fourth phase difference component and the polarization component (specifically a polarization film) are bonded together via an ultraviolet curing adhesive layer (thickness 1μm).

[0252] In this way, an optical layered body was produced. The obtained optical layered body was subjected to the above-mentioned measurement of ellipticity.

[0253] <<Example 8>>

[0254] As shown in Table 1, the first phase difference component of Manufacturing Example 2, the second phase difference component of Manufacturing Example 3, the fifth phase difference component of Manufacturing Example 12, and the polarization component (polarization film / protective layer) of Manufacturing Example 1 are stacked in sequence. The stacking is performed in such a way that the angle between the absorption axis direction of the polarizer and the slow axis direction of the phase difference component (the first phase difference component, the second phase difference component, and the fifth phase difference component) reaches the value of Table 1. In addition, the first phase difference component and the second phase difference component are bonded together via an ultraviolet curing adhesive layer (thickness 1 μm). The second phase difference component and the fifth phase difference component are bonded together via a (meth) acrylic adhesive layer (thickness 23 μm). The fifth phase difference component and the polarization component (specifically a polarization film) are bonded together via an ultraviolet curing adhesive layer (thickness 1 μm).

[0255] In this way, an optical layered body was produced. The obtained optical layered body was subjected to the above-mentioned measurement of ellipticity.

[0256] <<Example 9>>

[0257] As shown in Table 1, the first phase difference component of Manufacturing Example 2, the second phase difference component of Manufacturing Example 3, and the polarization component (polarization film / protective layer) of Manufacturing Example 1 are stacked in sequence. The stacking is performed in such a way that the angle between the absorption axis direction of the polarizer and the slow axis direction of the phase difference component (the first phase difference component or the second phase difference component) reaches the value of Table 1. In addition, the first phase difference component and the second phase difference component are bonded together via an ultraviolet curing adhesive layer (thickness 1 μm). The second phase difference component and the polarization component (specifically, a polarization film) are bonded together via an ultraviolet curing adhesive layer (thickness 1 μm).

[0258] In this way, an optical layered body was produced. The obtained optical layered body was subjected to the above-mentioned measurement of ellipticity.

[0259] <<Example 10>>

[0260] An optical layered body was prepared in the same manner as in Example 8 except that the angle between the absorption axis direction of the polarizer and the slow axis direction of the fifth phase difference member was changed to the value shown in Table 1. The obtained optical layered body was subjected to the above-mentioned ellipticity measurement.

[0261] <<Comparative Example 1>>

[0262] As shown in Table 1, the second phase difference component of Manufacturing Example 3 and the polarizing component (polarizing film / protective layer) of Manufacturing Example 1 were stacked in sequence. The stacking was performed in such a manner that the angle formed by the absorption axis direction of the polarizer and the slow axis direction of the second phase difference component reached the value in Table 1. In addition, the second phase difference component and the polarizing component (specifically, the polarizing film) were bonded together via an ultraviolet curable adhesive layer (thickness 1 μm).

[0263] In this way, an optical layered body was produced. The obtained optical layered body was subjected to the above-mentioned measurement of ellipticity.

[0264] <<Comparative Examples 2 to 4>>

[0265] An optical layered body was prepared in the same manner as in Example 8 except that the angle between the absorption axis direction of the polarizer and the slow axis direction of the fifth phase difference member was changed to the value shown in Table 1. The obtained optical layered body was subjected to the above-mentioned ellipticity measurement.

[0266]

[0267] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above-described embodiments may be replaced with substantially the same configuration, a configuration that exhibits the same effects, or a configuration that can achieve the same purpose.

[0268] Industrial Applicability

[0269] The optical layered body of the present invention can be used for image display devices (typically, liquid crystal display devices and organic EL display devices), and can be particularly preferably used for retroreflective aerial imaging devices (aerial floating displays).

Claims

1. An optical laminate comprising: polarizing member, and a plurality of phase difference components arranged on the visible side of the polarization component, The ellipticity of the optical layered body measured at an azimuth angle of 0°, an elevation angle of 90°, and an elevation angle of 30° is 0.75 or more.

2. The optical layered body according to claim 1, wherein: The ellipticity of the optical layered body measured at an azimuth angle of 45°, an elevation angle of 90°, and an elevation angle of 30° is 0.70 or more.

3. The optical layered body according to claim 1 or 2, wherein: The plurality of phase difference components include, in order from the visible side: a first phase difference member having a refractive index of nz>nx=ny, A second phase difference member functioning as a λ / 4 member, a third phase difference member having a refractive index of nz>nx≥ny, and The fourth phase difference member has a refractive index of nx>ny≥nz.

4. The optical layered body according to claim 1 or 2, wherein: The plurality of phase difference components include, in order from the visible side: a first phase difference member having a refractive index of nz>nx=ny, a second phase difference member functioning as a λ / 4 member, and a fifth phase difference member having a refractive index of nx>nz>ny, An angle formed by the absorption axis direction of the polarization member and the slow axis direction of the fifth phase difference member is 90°±1.5° or less.

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