WO2025004793A1 - 偏光板、表示装置 - Google Patents

偏光板、表示装置 Download PDF

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Publication number
WO2025004793A1
WO2025004793A1 PCT/JP2024/021212 JP2024021212W WO2025004793A1 WO 2025004793 A1 WO2025004793 A1 WO 2025004793A1 JP 2024021212 W JP2024021212 W JP 2024021212W WO 2025004793 A1 WO2025004793 A1 WO 2025004793A1
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Prior art keywords
optically anisotropic
anisotropic layer
layer
polarizer
liquid crystal
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English (en)
French (fr)
Japanese (ja)
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浩樹 桑原
彩子 松本
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Fujifilm Corp
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Fujifilm Corp
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    • 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
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • 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
    • H10K50/86—Arrangements for improving contrast, e.g. preventing reflection of ambient light
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/10—OLED displays

Definitions

  • the present invention relates to a polarizing plate and a display device.
  • Patent Document 1 discloses a polarizing plate including a retardation film in which a predetermined optically anisotropic layer is laminated.
  • the inventors combined the retardation film described in Patent Document 1 with a polarizer and applied it to a display device as a polarizing plate, and when they evaluated the reflection characteristics of the resulting display device from the polarizing plate side, they found that in some cases further reduction in reflectance was necessary.
  • a polarizer (1) a polarizer; an optically anisotropic layer X having an in-plane retardation; An optically anisotropic layer X and an adjacent layer X adjacent to each other, the difference in refractive index between the optically anisotropic layer X and the adjacent layer X in the transmission axis direction of the polarizer is 0.15 or less; The refractive index anisotropy ⁇ n of the optically anisotropic layer X is 0.09 or less, A polarizing plate, in which the angle between the transmission axis of the polarizer and the in-plane slow axis of the optically anisotropic layer X is 20° or less.
  • the optically anisotropic layer further includes an adjacent layer Y disposed on the side opposite to the optically anisotropic layer X side of the optically anisotropic layer Y, the adjacent layer Y being adjacent to the optically anisotropic layer Y; the difference in refractive index between the optically anisotropic layer X and the optically anisotropic layer Y in the transmission axis direction of the polarizer is 0.15 or less;
  • a display device comprising a display element and the polarizing plate according to any one of (1) to (6).
  • the display element is an organic electroluminescence display element.
  • the present invention it is possible to provide a polarizing plate that can realize a low reflectance when applied to a display device.
  • the present invention also provides a display device.
  • FIG. 1 is a diagram conceptually illustrating an embodiment of a polarizing plate of the present invention.
  • FIG. 2 is a diagram showing the relationship between the absorption axis of a polarizer and the in-plane slow axes of a second optically anisotropic layer and a third optically anisotropic layer in one embodiment of the polarizing plate of the present invention.
  • FIG. 3 is a schematic diagram showing the relationship between the absorption axis of a polarizer and the angle between the absorption axis of a polarizer and the in-plane slow axis of each of a second optically anisotropic layer and a third optically anisotropic layer when observed from the direction of a white arrow in FIG. 2 .
  • the in-plane slow axis and the in-plane fast axis are defined at a wavelength of 550 nm unless otherwise specified.
  • the in-plane slow axis direction it means the direction of the in-plane slow axis at a wavelength of 550 nm.
  • the refractive index is defined at a wavelength of 550 nm unless otherwise specified.
  • Re( ⁇ ) and Rth( ⁇ ) respectively represent the in-plane retardation and the retardation in the thickness direction at a wavelength ⁇ .
  • the wavelength ⁇ is 550 nm.
  • Re( ⁇ ) and Rth( ⁇ ) are values measured at a wavelength ⁇ using an AxoScan OPMF-1 (manufactured by Optosciences Inc.).
  • AxoScan OPMF-1 manufactured by Optosciences Inc.
  • NAR-4T Abbe refractometer
  • the average refractive index can be measured by measuring a film fixed in an optically isotropic phase by this method.
  • the A plate and the C plate are defined as follows. There are two types of A plates, positive A plates and negative A plates, and when the refractive index in the slow axis direction (the direction in which the refractive index in the plane is maximum) in the film plane is nx, the refractive index in the direction perpendicular to the slow axis in the plane is ny, and the refractive index in the thickness direction is nz, the positive A plate satisfies the relationship of formula (A1), and the negative A plate satisfies the relationship of formula (A2). Note that the positive A plate has a positive Rth value, and the negative A plate has a negative Rth value.
  • Formula (A1) nx>ny ⁇ nz
  • Formula (A2) ny ⁇ nx ⁇ nz
  • ⁇ includes not only the case where the two are completely identical, but also the case where the two are substantially identical.
  • “ny ⁇ nz” includes the case where (ny-nz) ⁇ d (where d is the thickness of the film) is -10 to 10 nm, preferably -5 to 5 nm
  • “nx ⁇ nz” includes the case where (nx-nz) ⁇ d is -10 to 10 nm, preferably -5 to 5 nm.
  • ultraviolet rays refers to light having a wavelength of 10 nm or more and less than 400 nm.
  • orthogonal and parallel include the range of error permitted in the technical field to which the present invention pertains. For example, it means being within a range of ⁇ 5° from the exact angle, and the error from the exact angle is preferably within a range of ⁇ 3°.
  • Fig. 1 shows a schematic cross-sectional view of one embodiment of the polarizing plate of the present invention.
  • the circular polarizing plate 100 includes a polarizer 20, a first optically anisotropic layer 12, a second optically anisotropic layer 14, a third optically anisotropic layer 16, and a fourth optically anisotropic layer 18 in this order.
  • the first optically anisotropic layer 12 is a negative C plate
  • the second optically anisotropic layer 14 is a negative A plate
  • the third optically anisotropic layer 16 is a layer formed by fixing rod-shaped liquid crystal compounds twisted and oriented along a helical axis extending in the thickness direction
  • the fourth optically anisotropic layer 18 is a positive C plate.
  • the in-plane slow axis of the second optically anisotropic layer 14 is parallel to the in-plane slow axis of the third optically anisotropic layer 16 on the surface facing the second optically anisotropic layer 14 .
  • the second optically anisotropic layer 14 corresponds to the optically anisotropic layer X having an in-plane retardation contained in the polarizing plate of the present invention
  • the first optically anisotropic layer 12 corresponds to the optically anisotropic layer Y having a retardation in the thickness direction contained in the polarizing plate of the present invention.
  • a first adhesion layer 30 is disposed between the second optically anisotropic layer 14 and the third optically anisotropic layer 16, and the first adhesion layer 30 is disposed adjacent to the second optically anisotropic layer 14.
  • the first adhesion layer 30 corresponds to an adjacent layer X adjacent to the optically anisotropic layer X included in the polarizing plate of the present invention.
  • a second adhesion layer 32 is disposed between the polarizer 20 and the first optically anisotropic layer 12, and the second adhesion layer 32 is disposed adjacent to the first optically anisotropic layer 12.
  • the second adhesion layer 32 corresponds to an adjacent layer Y adjacent to the optically anisotropic layer Y included in the polarizing plate of the present invention.
  • the polarizer 20, the second optically anisotropic layer 14, and the first adhesive layer 30 in the circular polarizing plate 100 are essential components, and the other components are optional components.
  • the difference in refractive index between the second optically anisotropic layer 14, which is the optically anisotropic layer X, and the first adhesive layer 30, which is the adjacent layer X, in the transmission axis direction of the polarizer 20 is 0.15 or less, and is preferably 0.13 or less, more preferably 0.12 or less, in terms of lowering the reflectance in a display device including the polarizing plate of the present invention (hereinafter, also simply referred to as "the point where the effect of the present invention is better").
  • the lower limit of the difference is not particularly limited, and is often 0 or more, more often 0.05 or more, and even more often 0.10 or more.
  • the difference between the refractive index of the second optically anisotropic layer 14, which is the optically anisotropic layer X, and the refractive index of the first adhesive layer 30, which is the adjacent layer X is equal to or less than the above-mentioned predetermined value, reflection is suppressed at the interface between the second optically anisotropic layer 14, which is the optically anisotropic layer X, and the first adhesive layer 30, which is the adjacent layer X.
  • the light that has passed through the polarizer 20 is polarized parallel to the transmission axis, by adjusting the refractive index difference in the transmission axis direction of the polarizer 20, it is possible to reduce the reflectance more than in the conventional technology.
  • the method for adjusting the refractive index of the second optically anisotropic layer 14, which is the optically anisotropic layer X is not particularly limited, and examples of the method include a method of adjusting the manufacturing conditions of the optically anisotropic layer (particularly, the heating temperature) and a method of using a predetermined additive, as described later.
  • the refractive index of the second optically anisotropic layer 14 which is the optically anisotropic layer X and the refractive index of the first adhesive layer 30 which is the adjacent layer X are both refractive indices at a wavelength of 550 nm.
  • the method for measuring the refractive index difference is as follows.
  • the refractive index of the second optically anisotropic layer 14, which is the optically anisotropic layer X in the transmission axis direction of the polarizer 20, first, ne and no of the second optically anisotropic layer 14, which is the optically anisotropic layer X, are calculated. Specifically, the complex reflectance of the second optically anisotropic layer 14, which is the optically anisotropic layer X, at an incidence angle of 50 to 70°, obtained by ellipsometry, is analyzed using an optical model that takes into account the anisotropy of the refractive index, and ne and no of the second optically anisotropic layer 14, which is the optically anisotropic layer X, are obtained.
  • the refractive index of the polarizer 20 in the transmission axis direction is calculated from the obtained ne and no.
  • the refractive index is measured at a wavelength of 550 nm.
  • the measuring device used may be a Woollam RC2 or a Semilab SE-2000.
  • the refractive index of the first adhesion layer 30, which is the adjacent layer X in the transmission axis direction of the polarizer 20 is measured according to a procedure similar to the above-mentioned method for measuring the refractive index of the second optically anisotropic layer 14, which is the optically anisotropic layer X in the transmission axis direction of the polarizer 20.
  • the difference between the refractive index of the first adhesion layer 30, which is the adjacent layer X in the transmission axis direction of the polarizer 20, and the refractive index of the second optically anisotropic layer 14, which is the optically anisotropic layer X in the transmission axis direction of the polarizer 20, is calculated.
  • the angle between the transmission axis of the polarizer 20 and the in-plane slow axis of the second optically anisotropic layer 14, which is the optically anisotropic layer X is 20° or less.
  • an angle of 18° or less is preferable, and 16° or less is more preferable.
  • the difference in refractive index between the second optically anisotropic layer 14, which is the optically anisotropic layer X, and the first optically anisotropic layer 12, which is the optically anisotropic layer Y, in the transmission axis direction of the polarizer 20 is not particularly limited, but in terms of better effects of the present invention, it is preferably 0.15 or less, more preferably 0.10 or less, and even more preferably 0.05 or less.
  • the lower limit of the difference is not particularly limited, and is often 0 or more, more often 0.02 or more, and even more often 0.03 or more.
  • the refractive index of the second optically anisotropic layer 14 which is the optically anisotropic layer X and the refractive index of the first optically anisotropic layer 12 which is the optically anisotropic layer Y are both refractive indices at a wavelength of 550 nm.
  • the difference between the refractive index of the second optically anisotropic layer 14, which is the optically anisotropic layer X, and the refractive index of the first optically anisotropic layer 12, which is the optically anisotropic layer Y, is not more than the above-mentioned specified value, reflection at the interface between the second optically anisotropic layer 14, which is the optically anisotropic layer X, and the first optically anisotropic layer 12, which is the optically anisotropic layer Y, is suppressed.
  • the method for measuring the difference in refractive index may be the same as that described above for measuring the difference in refractive index between the second optically anisotropic layer 14 as the optically anisotropic layer X and the first adhesive layer 30 as the adjacent layer X.
  • the difference in refractive index between the first optically anisotropic layer 12, which is the optically anisotropic layer Y, and the second adhesive layer 32, which is the adjacent layer Y, in the transmission axis direction of the polarizer 20 is not particularly limited, but is preferably 0.15 or less, and more preferably 0.14 or less, in terms of better effects of the present invention.
  • the lower limit of the difference is not particularly limited, and is often 0 or more, more often 0.05 or more, and even more often 0.10 or more.
  • the difference between the refractive index of the first optically anisotropic layer 12, which is the optically anisotropic layer Y, and the refractive index of the second adhesion layer 32, which is the adjacent layer Y, is less than the above-mentioned specified value, reflection at the interface between the first optically anisotropic layer 12, which is the optically anisotropic layer Y, and the second adhesion layer 32, which is the adjacent layer Y, is suppressed.
  • the method for measuring the difference in refractive index may be the same as that described above for measuring the difference in refractive index between the second optically anisotropic layer 14 as the optically anisotropic layer X and the first adhesive layer 30 as the adjacent layer X.
  • the first optically anisotropic layer 12 corresponds to the optically anisotropic layer Y having a retardation in the thickness direction, which is included in the polarizing plate of the present invention.
  • the first optically anisotropic layer 12 is preferably a negative C plate.
  • the retardation in the thickness direction of the first optically anisotropic layer 12 at a wavelength of 550 nm is not particularly limited, but is preferably 5 to 100 nm, more preferably 10 to 90 nm, even more preferably 15 to 50 nm, and particularly preferably 30 nm or more and less than 40 nm, in that when the polarizing plate of the present invention is applied to a display device and the display device is observed at all azimuth angles from an oblique direction, the change in color is smaller.
  • the refractive index of the first optically anisotropic layer 12 is not particularly limited, but is preferably 1.55 to 1.65, and more preferably 1.57 to 1.63.
  • the structure of the first optically anisotropic layer 12 is not particularly limited.
  • a negative C plate it may be a layer in which horizontally aligned discotic liquid crystal compounds are fixed, and a resin film.
  • the state in which the discotic liquid crystal compound is horizontally aligned means that the disc surface of the discotic liquid crystal compound is parallel to the main surface of the layer, but it is not required that they be strictly parallel, and the angle between the disc surface and the main surface of the layer is preferably within a range of 0 ⁇ 20°, and more preferably within a range of 0 ⁇ 10°.
  • the "fixed" state refers to a state in which the alignment of the liquid crystal compound is maintained.
  • the layer has no fluidity in a temperature range of usually 0 to 50° C., or under more severe conditions, ⁇ 30 to 70° C., and that the alignment state is not changed by an external field or external force, and the fixed alignment state can be stably maintained.
  • discotic liquid crystal compound known compounds can be used.
  • the discotic liquid crystal compound include the compounds described in paragraphs 0020 to 0067 of JP-A-2007-108732 and paragraphs 0013 to 0108 of JP-A-2010-244038.
  • the discotic liquid crystal compound may have a polymerizable group.
  • the type of polymerizable group is not particularly limited, and a functional group capable of an addition polymerization reaction is preferable, a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferable, and a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group is further preferable.
  • the first optically anisotropic layer 12 is preferably a layer formed by fixing a horizontally aligned discotic liquid crystal compound having a polymerizable group by polymerization.
  • the first optically anisotropic layer 12 is preferably a layer formed using a thermotropic liquid crystal compound.
  • the thickness of the first optically anisotropic layer 12 is not particularly limited.
  • the thickness of the first optically anisotropic layer 12 is preferably 10 ⁇ m or less, more preferably 0.1 to 5.0 ⁇ m, and even more preferably 0.3 to 2.0 ⁇ m.
  • the thickness of the first optically anisotropic layer 12 is preferably from 10 to 100 ⁇ mm, and more preferably from 15 to 90 ⁇ m.
  • the thickness of the first optically anisotropic layer 12 is preferably 520 nm ⁇ 40 nm, 690 nm ⁇ 40 nm, 860 nm ⁇ 40 nm, or 980 nm or more, in terms of better effects of the present invention.
  • the thickness of the first optically anisotropic layer 12 refers to the average thickness of the first optically anisotropic layer 12. The average thickness is determined by measuring the thicknesses of any five or more points of the first optically anisotropic layer 12 and calculating the arithmetic average.
  • the second optically anisotropic layer 14 corresponds to the optically anisotropic layer X having an in-plane retardation, which is included in the polarizing plate of the present invention.
  • the second optically anisotropic layer 14 is preferably a negative A plate.
  • the in-plane retardation of the second optically anisotropic layer 14 at a wavelength of 550 nm is not particularly limited, but is preferably from 120 to 240 nm, more preferably from 130 to 230 nm, in terms of obtaining better effects of the present invention.
  • the retardation in the thickness direction of the second optically anisotropic layer 14 at a wavelength of 550 nm is not particularly limited, but is preferably ⁇ 120 to ⁇ 60 nm, more preferably ⁇ 115 to ⁇ 65 nm, in terms of superior effects of the present invention.
  • the refractive index anisotropy ⁇ n of the second optically anisotropic layer 14 is 0.09 or less, and from the viewpoint of the superior effect of the present invention, 0.08 or less is more preferable.
  • the lower limit of the refractive index anisotropy ⁇ n of the second optically anisotropic layer 14 is not particularly limited, but from the viewpoint of thinning, it is preferably 0.03 or more, and more preferably 0.05 or more.
  • the refractive index anisotropy ⁇ n means the refractive index anisotropy of the optically anisotropic layer (the difference between the refractive index on the in-plane slow axis and the refractive index on the in-plane fast axis).
  • the refractive index anisotropy ⁇ n is a value at a wavelength of 550 nm.
  • the refractive index of the second optically anisotropic layer 14 is not particularly limited, but is preferably 1.55 to 1.65, and more preferably 1.57 to 1.60.
  • the second optically anisotropic layer 14 may exhibit forward wavelength dispersion (the property that the in-plane retardation decreases as the measured wavelength increases) or may exhibit reverse wavelength dispersion (the property that the in-plane retardation increases as the measured wavelength increases). Note that the forward wavelength dispersion and reverse wavelength dispersion are preferably exhibited in the visible light range.
  • the second optically anisotropic layer 14 is not particularly limited in its configuration.
  • examples of the layer include a layer in which a discotic liquid crystal compound is fixed that is vertically oriented and whose optical axis (axis perpendicular to the disc surface) is aligned in the same direction, and a stretched film.
  • a layer in which a discotic liquid crystal compound is fixed that is vertically oriented and whose optical axis (axis perpendicular to the disc surface) is aligned in the same direction is preferred.
  • the state in which the discotic liquid crystal compound is vertically aligned means that the disc surface of the discotic liquid crystal compound is parallel to the thickness direction of the layer, but this is not required to be strictly parallel, and the angle between the disc surface and the thickness direction of the layer is preferably within a range of 0 ⁇ 20°, and more preferably within a range of 0 ⁇ 10°.
  • the state in which the optical axes (axes perpendicular to the disc surface) of the discotic liquid crystal compounds are aligned in the same direction does not require that they be aligned in the same direction strictly, but means that when the orientations of the slow axes are measured at any 20 positions within the plane, the maximum difference between the slow axis orientations at the 20 positions (the difference between the two slow axis orientations with the largest difference among the 20 slow axis orientations) is less than 2°.
  • the discotic liquid crystal compound include the discotic liquid crystal compounds exemplified for the first optically anisotropic layer 12 .
  • the discotic liquid crystal compound may have a polymerizable group.
  • the type of the polymerizable group that the discotic liquid crystal compound may have is as described above.
  • the second optically anisotropic layer 14 is preferably a layer formed by fixing a discotic liquid crystal compound having a polymerizable group by polymerization.
  • the second optically anisotropic layer 14 is preferably a layer formed using a thermotropic liquid crystal compound.
  • the thickness of the second optically anisotropic layer 14 is not particularly limited, and is preferably 10 ⁇ m or less, more preferably 0.1 to 5.0 ⁇ m, and even more preferably 0.3 to 3.0 ⁇ m.
  • the thickness of the second optically anisotropic layer 14 refers to the average thickness of the second optically anisotropic layer 14. The average thickness is determined by measuring the thicknesses of the second optically anisotropic layer 14 at any five or more points and calculating the arithmetic average.
  • the third optically anisotropic layer 16 is preferably a layer in which rod-like liquid crystal compounds are fixed and twisted along a helical axis extending in the thickness direction.
  • the third optically anisotropic layer 16 is preferably a layer formed by fixing a chiral nematic phase having a so-called helical structure.
  • the twist angle of the rod-shaped liquid crystal compounds is not particularly limited and is often more than 0° and not more than 360°.
  • the twist angle is preferably within the range of 80 ⁇ 30° (within the range of 50 to 110°), and more preferably within the range of 80 ⁇ 20° (within the range of 60 to 100°).
  • the torsion angle is measured using an AxoScan (polarimeter) device manufactured by Axometrics Inc. and the device analysis software of the same company.
  • the twisted alignment of the rod-shaped liquid crystal compounds means that the rod-shaped liquid crystal compounds are twisted around the thickness direction of the third optically anisotropic layer 16 from one main surface to the other main surface of the third optically anisotropic layer 16. Accordingly, the alignment direction (in-plane slow axis direction) of the rod-shaped liquid crystal compounds differs depending on the position in the thickness direction of the third optically anisotropic layer 16. In the twisted orientation, the long axes of the rod-shaped liquid crystal compounds are arranged so as to be parallel to the main surface of the third optically anisotropic layer 16.
  • the angle between the long axes of the rod-shaped liquid crystal compounds and the main surface of the third optically anisotropic layer 16 is preferably within the range of 0 ⁇ 20°, and more preferably within the range of 0 ⁇ 10°.
  • the value of the product ⁇ nd of the refractive index anisotropy ⁇ n of the third optical anisotropic layer 16 at a wavelength of 550 nm and the thickness d of the third optical anisotropic layer 16 is not particularly limited, but is preferably 120 to 240 nm, and more preferably 130 to 230 nm, in terms of superior effects of the present invention.
  • the above ⁇ nd is measured using an AxoScan (polarimeter) device manufactured by Axometrics and the device analysis software of the same company.
  • the angle between the in-plane slow axis of the second optically anisotropic layer 14 and the in-plane slow axis of the third optically anisotropic layer 16 on the surface facing the second optically anisotropic layer 14 is not particularly limited, but is preferably in the range of 0 to 30°, and more preferably in the range of 0 to 20°.
  • the type of rod-like liquid crystal compound used to form the third optically anisotropic layer 16 is not particularly limited, and examples thereof include known compounds.
  • Examples of the rod-shaped liquid crystal compound include the compounds described in claim 1 of JP-T-11-513019 and in paragraphs 0026 to 0098 of JP-A-2005-289980.
  • the rod-shaped liquid crystal compound may have a polymerizable group.
  • the type of polymerizable group that the rod-shaped liquid crystal compound may have is as described above.
  • the third optically anisotropic layer 16 is preferably a layer formed by fixing a rod-shaped liquid crystal compound having a polymerizable group through polymerization. More specifically, it is more preferable that the third optically anisotropic layer 16 is a layer formed by fixing a rod-shaped liquid crystal compound having a twisted polymerizable group through polymerization.
  • the thickness of the third optically anisotropic layer 16 is not particularly limited, and is preferably 10 ⁇ m or less, more preferably 0.1 to 5.0 ⁇ m, and even more preferably 0.3 to 3.0 ⁇ m.
  • the thickness of the third optically anisotropic layer 16 refers to the average thickness of the third optically anisotropic layer 16. The average thickness is determined by measuring the thicknesses of any five or more points of the third optically anisotropic layer 16 and calculating the arithmetic average thereof.
  • the fourth optically anisotropic layer 18 is preferably a positive C plate.
  • the retardation in the thickness direction of the fourth optically anisotropic layer 18 at a wavelength of 550 nm is not particularly limited, but is preferably ⁇ 100 to ⁇ 10 nm, more preferably ⁇ 100 to ⁇ 30 nm, in terms of superior effects of the present invention.
  • the configuration of the fourth optically anisotropic layer 18 is not particularly limited.
  • examples of the configuration include a layer in which vertically aligned rod-like liquid crystal compounds are fixed, and a resin film.
  • a layer in which vertically aligned rod-like liquid crystal compounds are fixed is preferred.
  • the state in which the rod-like liquid crystal compounds are vertically aligned means that the long axes of the rod-like liquid crystal compounds are parallel to the thickness direction of the fourth optically anisotropic layer 18.
  • the angle between the long axes of the rod-like liquid crystal compounds and the thickness direction of the fourth optically anisotropic layer 18 is preferably within the range of 0 ⁇ 20°, and more preferably within the range of 0 ⁇ 10°.
  • rod-shaped liquid crystal compound known compounds can be used.
  • the rod-shaped liquid crystal compound include the rod-shaped liquid crystal compounds exemplified for the third optically anisotropic layer 16 .
  • the rod-shaped liquid crystal compound may have a polymerizable group.
  • the type of polymerizable group that the rod-shaped liquid crystal compound may have is as described above.
  • the fourth optically anisotropic layer 18 is preferably a layer formed by fixing vertically aligned rod-shaped liquid crystal compounds having polymerizable groups by polymerization.
  • the thickness of the fourth optically anisotropic layer 18 is not particularly limited, and is preferably 10 ⁇ m or less, more preferably 0.1 to 5.0 ⁇ m, and even more preferably 0.3 to 2.0 ⁇ m.
  • the thickness of the fourth optically anisotropic layer 18 refers to the average thickness of the fourth optically anisotropic layer 18. The average thickness is determined by measuring the thicknesses of any five or more points of the fourth optically anisotropic layer 18 and calculating the arithmetic average thereof.
  • the polarizer 20 may be any member having a function of converting natural light into a specific linearly polarized light, and may be, for example, an absorptive polarizer.
  • an absorptive polarizer There is no particular limitation on the type of polarizer 20, and any commonly used polarizer can be used, such as an iodine-based polarizer, a dye-based polarizer using a dichroic material, and a polyene-based polarizer.
  • Iodine-based polarizers and dye-based polarizers are generally produced by adsorbing iodine or a dichroic dye to polyvinyl alcohol and stretching it.
  • a protective film may be disposed on one or both sides of the polarizer 20 .
  • the first adhesion layer 30 and the second adhesion layer 32 are disposed between the respective members and have the function of adhering the members to each other.
  • the refractive index of the first adhesive layer 30 and the second adhesive layer 32 is not particularly limited, but is preferably 1.40 to 1.55, and more preferably 1.45 to 1.50.
  • the first adhesion layer 30 and the second adhesion layer 32 may be a known pressure-sensitive adhesive layer and adhesive layer.
  • the thickness of the first adhesion layer 30 and the second adhesion layer 32 is preferably 0.1 to 50 ⁇ m. From the viewpoint of thinning, it is more preferably 25 ⁇ m or less, even more preferably 15 ⁇ m or less, and particularly preferably 5 ⁇ m or less. From the viewpoint of preventing interference unevenness, it is more preferably 5 ⁇ m or more, even more preferably 15 ⁇ m or more, and particularly preferably 25 ⁇ m or more.
  • the circularly polarizing plate 100 may include other components in addition to the components described above.
  • the circularly polarizing plate 100 may further include an alignment film.
  • the alignment film may be disposed between each of the optically anisotropic layers. It is preferable that the circularly polarizing plate 100 does not have an alignment film between the optically anisotropic layers.
  • the alignment layer can be formed by such means as rubbing an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having microgrooves, or accumulation of an organic compound (e.g., ⁇ -tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearate) by the Langmuir-Blodgett method (LB film).
  • an alignment film is also known which exhibits an alignment function when an electric field is applied, a magnetic field is applied, or light (preferably polarized light) is irradiated.
  • the alignment film is preferably formed by a rubbing treatment of a polymer.
  • the alignment film also includes a photoalignment film.
  • the thickness of the alignment film is not particularly limited as long as it can exhibit an alignment function, but is preferably 0.01 to 5.0 ⁇ m, more preferably 0.05 to 2.0 ⁇ m, and even more preferably 0.1 to 0.5 ⁇ m.
  • the circularly polarizing plate 100 may further include a substrate.
  • the substrate is preferably a transparent substrate.
  • the transparent substrate refers to a substrate having a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more.
  • the thickness of the substrate is not particularly limited, but is preferably from 10 to 200 ⁇ m, more preferably from 10 to 100 ⁇ m, and even more preferably from 20 to 90 ⁇ m.
  • the substrate may also be made of a laminate of multiple sheets.
  • the surface of the substrate may be subjected to a surface treatment (e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment) to improve adhesion with a layer provided thereon.
  • a surface treatment e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment
  • an adhesive layer undercoat layer
  • the substrate may be a so-called temporary support. For example, after the optically anisotropic layer is produced on the substrate, the substrate may be peeled off from the optically anisotropic layer, if necessary.
  • FIG. 2 is a diagram showing the relationship between the absorption axis of the polarizer 20 and the in-plane slow axes of the second optically anisotropic layer 14 and the third optically anisotropic layer 16 in the circular polarizing plate 100 shown in Fig. 1. Note that the arrows in the polarizer 20 in Fig. 2 represent the absorption axis, and the arrows in the second optically anisotropic layer 14 and the third optically anisotropic layer 16 represent the in-plane slow axes in the respective layers.
  • FIG. 1 Axial relationship of each layer
  • FIG. 3 is a diagram showing the relationship between the absorption axis (dashed line) of the polarizer 20 and the in-plane slow axes (solid lines) of the second optically anisotropic layer 14 and the third optically anisotropic layer 16 when observed from the white arrow in FIG. 1 .
  • the rotation angle of the in-plane slow axis is expressed as a positive angle in the counterclockwise direction and a negative angle in the clockwise direction with respect to the absorption axis of the polarizer 20 as the reference (0°) when observed from the white arrow in Fig. 1.
  • the twist direction of the liquid crystal compound is determined as right twist (clockwise) or left twist (counterclockwise) based on the in-plane slow axis on the surface of the front side (opposite the polarizer 20 side) of the third optically anisotropic layer 16 when observed from the white arrow in Fig. 1.
  • the angle ⁇ a1 between the absorption axis of the polarizer 20 and the in-plane slow axis of the second optically anisotropic layer 14 is 76°. More specifically, the in-plane slow axis of the second optically anisotropic layer 14 rotates 76° (76° counterclockwise) with respect to the absorption axis of the polarizer 20. Note that, although Figures 2 and 3 show an embodiment in which the in-plane slow axis of the second optically anisotropic layer 14 is at a position of 76°, the present invention is not limited to this embodiment and falls within the range of 70 to 90°.
  • the angle between the absorption axis of the polarizer 20 and the in-plane slow axis of the second optically anisotropic layer 14 is within the range of 70 to 90°. In other words, the angle between the transmission axis of the polarizer 20 and the in-plane slow axis of the second optically anisotropic layer 14 is 20° or less (0 to 20°).
  • the in-plane slow axis at surface 141 facing the polarizer 20 of the second optically anisotropic layer 14 is parallel to the in-plane slow axis at surface 142 facing the third optically anisotropic layer 16 of the second optically anisotropic layer 14.
  • the in-plane slow axis of the second optically anisotropic layer 14 and the in-plane slow axis of the third optically anisotropic layer 16 on the second optically anisotropic layer 14 side are parallel to each other.
  • FIG. 2 and 3 show an embodiment in which the in-plane slow axis of the second optically anisotropic layer 14 and the in-plane slow axis of the third optically anisotropic layer 16 on the second optically anisotropic layer 14 side are parallel, but the present invention is not limited to this embodiment, and it is preferable that the angle between the in-plane slow axis of the second optically anisotropic layer 14 and the in-plane slow axis of the third optically anisotropic layer 16 on the second optically anisotropic layer 14 side is within the range of 0 to 30°. Therefore, for example, when observed from the white arrow in FIG.
  • the in-plane slow axis of the second optically anisotropic layer 14 on the surface 161 of the third optically anisotropic layer 16 may be arranged at a position 30° clockwise or 30° counterclockwise based on the in-plane slow axis of the second optically anisotropic layer 14.
  • the third optically anisotropic layer 16 is a layer in which rod-shaped liquid crystal compounds are fixed and twisted along a helical axis extending in the thickness direction.
  • the in-plane slow axis of the third optically anisotropic layer 16 on the second optically anisotropic layer 14 side and the in-plane slow axis of the third optically anisotropic layer 16 on the surface 162 opposite to the second optically anisotropic layer 14 side form the above-mentioned twist angle (80° in Figure 2).
  • the angle ⁇ a2 between the in-plane slow axis of the third optically anisotropic layer 16 on the second optically anisotropic layer 14 side and the in-plane slow axis of the third optically anisotropic layer 16 on the surface 161 opposite to the second optically anisotropic layer 14 side is 80°.
  • the twist direction of the rod-like liquid crystal compound in the third optically anisotropic layer 16 is left-handed (counterclockwise), and the twist angle is 80°. Therefore, the angle between the absorption axis of the polarizer 20 and the in-plane slow axis on the surface 162 of the third optically anisotropic layer 16 opposite to the second optically anisotropic layer 14 side is 4°.
  • 2 and 3 show an embodiment in which the twist angle of the rod-shaped liquid crystal compound in the third optically anisotropic layer 16 is 80°, but the present invention is not limited to this embodiment, and the twist angle of the rod-shaped liquid crystal compound is preferably within a range of 80 ⁇ 30°.
  • the angle between the in-plane slow axis of the surface 161 of the third optically anisotropic layer 16 facing the second optically anisotropic layer 14 and the in-plane slow axis of the surface 162 of the third optically anisotropic layer 16 facing away from the second optically anisotropic layer 14 is preferably within a range of 80 ⁇ 30°.
  • the in-plane slow axis of the second optically anisotropic layer 14 is rotated 76° clockwise with respect to the absorption axis of the polarizer 20, and the twist direction of the rod-like liquid crystal compound in the third optically anisotropic layer 16 may be clockwise (right twist).
  • the twist direction of the rod-like liquid crystal compound in the third optically anisotropic layer is counterclockwise with respect to the in-plane slow axis on the surface of the third optically anisotropic layer on the fourth optically anisotropic layer side.
  • the twist direction of the rod-like liquid crystal compound in the third optically anisotropic layer is clockwise with respect to the in-plane slow axis on the surface of the third optically anisotropic layer on the fourth optically anisotropic layer side.
  • the method for producing the circularly polarizing plate is not particularly limited, and may be any known method.
  • a method in which a polarizer and a retardation film including the first optically anisotropic layer 12 to the fourth optically anisotropic layer 18 are attached via an adhesive layer can be mentioned.
  • the method for producing the retardation film is not particularly limited, and any known method can be used.
  • the first to fourth optically anisotropic layers are prepared and then laminated in a predetermined order via an adhesive layer (eg, a pressure sensitive adhesive layer or an adhesive layer) to produce a retardation film.
  • the first to fourth optically anisotropic layers can be produced using compositions for forming optically anisotropic layers, each of which contains a liquid crystal compound having a polymerizable group.
  • optically anisotropic layers first to fourth optically anisotropic layers
  • a composition for forming an optically anisotropic layer that contains a liquid crystal compound having a polymerizable group.
  • the liquid crystal compound having a polymerizable group contained in the composition for forming an optically anisotropic layer (hereinafter also referred to as "polymerizable liquid crystal compound”) is as described above.
  • a rod-shaped liquid crystal compound and a discotic liquid crystal compound are appropriately selected depending on the properties of the optically anisotropic layer to be formed.
  • the content of the polymerizable liquid crystal compound in the composition for forming an optically anisotropic layer is preferably from 60 to 99% by mass, more preferably from 70 to 98% by mass, based on the total solid content of the composition for forming an optically anisotropic layer.
  • the solid content means a component capable of forming an optically anisotropic layer from which the solvent has been removed, and even if the component is in a liquid state, it is considered to be a solid content.
  • the composition for forming an optically anisotropic layer may contain compounds other than the liquid crystal compound having a polymerizable group.
  • the composition for forming the optically anisotropic layer for forming the third optically anisotropic layer 16 preferably contains a chiral agent in order to cause the liquid crystal compound to be twisted.
  • the chiral agent is added to cause the liquid crystal compound to be twisted, but of course, when the liquid crystal compound is a compound that exhibits optical activity, such as having an asymmetric carbon in the molecule, the addition of the chiral agent is not necessary. Also, depending on the manufacturing method and twist angle, the addition of the chiral agent is not necessary.
  • the chiral agent is not particularly limited in structure as long as it is compatible with the liquid crystal compound used in combination. Any of the known chiral agents (for example, those described in "Liquid Crystal Device Handbook," edited by the 142nd Committee of the Japan Society for the Promotion of Science, Chapter 3, Section 4-3, Chiral Agents for TN and STN, p. 199, 1989) can be used.
  • the amount of the chiral agent used is not particularly limited, and is adjusted so as to achieve the above-mentioned twist angle.
  • the composition for forming an optically anisotropic layer may contain a polymerization initiator.
  • the polymerization initiator to be used is selected depending on the type of polymerization reaction, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator.
  • the content of the polymerization initiator in the composition for forming an optically anisotropic layer is preferably from 0.01 to 20% by mass, more preferably from 0.5 to 10% by mass, based on the total solid content of the composition for forming an optically anisotropic layer.
  • compositions for forming the optically anisotropic layer include, in addition to those mentioned above, polyfunctional monomers, alignment control agents (vertical alignment agents, horizontal alignment agents), surfactants, adhesion improvers, plasticizers, and solvents.
  • alignment control agents vertical alignment agents, horizontal alignment agents
  • surfactants adhesion improvers, plasticizers, and solvents.
  • Methods for applying the composition for forming the optically anisotropic layer include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, and wire bar methods.
  • the formed coating film is subjected to an alignment treatment to align the polymerizable liquid crystal compound in the coating film.
  • the discotic liquid crystal compound is aligned horizontally.
  • the discotic liquid crystal compound is aligned vertically, so that the optical axes (axes perpendicular to the disc surface) of the discotic liquid crystal compound are aligned in the same direction.
  • the rod-shaped liquid crystal compound is aligned in a twisted manner.
  • the fourth optically anisotropic layer 18 the rod-shaped liquid crystal compound is aligned vertically.
  • the alignment treatment can be carried out by drying the coating film at room temperature or by heating the coating film.
  • the liquid crystal phase formed by the alignment treatment can generally be transitioned by a change in temperature or pressure.
  • the transition can also be caused by a composition ratio such as the amount of solvent.
  • the conditions for heating the coating are not particularly limited, but the heating temperature is preferably 50 to 250° C., more preferably 50 to 150° C., and the heating time is preferably 10 seconds to 10 minutes. After the coating film is heated, the coating film may be cooled, if necessary, before the curing treatment (light irradiation treatment) described below.
  • the coating film in which the polymerizable liquid crystal compound is aligned is subjected to a curing treatment.
  • the method of hardening treatment performed on the coating film in which the polymerizable liquid crystal compound is oriented is not particularly limited, and examples thereof include light irradiation treatment and heat treatment. Among them, from the viewpoint of manufacturability, light irradiation treatment is preferred, and ultraviolet irradiation treatment is more preferred.
  • the irradiation conditions for the light irradiation treatment are not particularly limited, but the amount of irradiation is preferably 50 to 1000 mJ/ cm2 .
  • the atmosphere during the light irradiation treatment is not particularly limited, but a nitrogen atmosphere is preferred.
  • the refractive index of the optically anisotropic layer in the transmission axis direction of the polarizer can be adjusted by changing the type of compound used.
  • the refractive index of the obtained optically anisotropic layer can be adjusted by adjusting the type and content of an additive (e.g., a polyfunctional monomer) for adjusting the refractive index.
  • the refractive index of the optically anisotropic layer in the transmission axis direction of the polarizer can be adjusted by changing the manufacturing conditions.
  • the refractive index of the obtained optically anisotropic layer can be adjusted by carrying out a heat treatment together with the light irradiation treatment and adjusting the temperature of the heat treatment.
  • the first optically anisotropic layer 12 is a negative C plate, but the present invention is not limited to this embodiment and may be a positive C plate.
  • the configuration of the optically anisotropic layer Y is not limited to the embodiment shown in FIG. 1
  • the second optically anisotropic layer 14 is a negative A plate, but the present invention is not limited to this embodiment and may be a positive A plate.
  • the configuration of the optically anisotropic layer X is not limited to the embodiment shown in FIG.
  • FIG. 1 an embodiment has been described in which the third optically anisotropic layer 16 is a layer formed by fixing rod-shaped liquid crystal compounds that are twisted and aligned along a helical axis extending in the thickness direction.
  • the present invention is not limited to this embodiment, and the third optically anisotropic layer 16 may be a layer formed by fixing discotic liquid crystal compounds that are twisted and aligned along a helical axis extending in the thickness direction.
  • the fourth optically anisotropic layer 18 is a positive C plate has been described, but the present invention is not limited to this embodiment and may be a negative C plate.
  • the polarizing plate of the present invention can be used for various purposes.
  • the polarizing plate of the present invention can be used as a circular polarizing plate.
  • a circular polarizing plate is an optical element that converts unpolarized light into circularly polarized light.
  • the circular polarizing plate of the present invention having the above-mentioned configuration is suitably used for anti-reflection applications in displays such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescence displays (ELDs), and cathode ray tube displays (CRTs).
  • LCDs liquid crystal displays
  • PDPs plasma display panels
  • ELDs electroluminescence displays
  • CRTs cathode ray tube displays
  • the polarizing plate of the present invention can be suitably applied to display devices.
  • the display device of the present invention comprises a display element and the above-mentioned polarizing plate (preferably a circular polarizing plate).
  • the display device of the present invention preferably has a surface protective film including a hard coat layer in addition to the display element and the above-mentioned polarizing plate.
  • the polarizing plate of the present invention is applied to a display device, it is preferably applied as the above-mentioned circular polarizing plate.
  • the circular polarizing plate is arranged on the viewing side
  • the polarizer in the circular polarizing plate is arranged on the viewing side.
  • the display device further has a surface protective film
  • the surface protective film is arranged on the viewing side further than the polarizer.
  • the display element is not particularly limited, and examples thereof include an organic electroluminescence display element and a liquid crystal display element.
  • Example 1 Preparation of Cellulose Acylate Film
  • the following composition was put into a mixing tank, stirred, and heated at 90° C. for 10 minutes.
  • the obtained composition was then filtered through a filter paper with an average pore size of 34 ⁇ m and a sintered metal filter with an average pore size of 10 ⁇ m to prepare a dope.
  • the dope prepared above was cast using a drum film-forming machine.
  • the dope was cast from a die so that it was in contact with a metal support cooled to 0°C, and then the resulting web (film) was peeled off.
  • the drum was made of SUS.
  • the web (film) obtained by casting was peeled off from the drum, and then dried for 20 minutes in a tenter apparatus, which clips both ends of the web with clips while transporting the film at 30 to 40°C.
  • the web was then post-dried by zone heating while being transported by rolls.
  • the obtained web was knurled and then wound up.
  • the thickness of the obtained cellulose acylate film was 40 ⁇ m, the in-plane retardation at a wavelength of 550 nm was 1 nm, and the retardation in the thickness direction at a wavelength of 550 nm was 26 nm.
  • the cellulose acylate film is also called an optically anisotropic layer (1a).
  • the above-mentioned cellulose acylate film was passed through a dielectric heating roll at a temperature of 60°C, and the film surface temperature was raised to 40°C. Then, an alkaline solution having the composition shown below was applied to the band surface of the film with a coating amount of 14 ml/ m2 using a bar coater, and the film was transported for 10 seconds under a steam type far-infrared heater manufactured by Noritake Co., Ltd., which was heated to 110°C. Then, 3 ml/ m2 of pure water was applied using the same bar coater. Next, after washing with water using a fountain coater and draining with an air knife three times, the film was transported to a drying zone at 70°C for 10 seconds and dried to prepare an alkaline saponified cellulose acylate film.
  • an alignment film coating solution 1 having the following composition was continuously coated with a wire bar of #14. The coating film thus obtained was then dried with hot air at 60° C. for 60 seconds and then with hot air at 100° C. for 120 seconds to obtain an alignment film 1.
  • the above-prepared alignment film 1 was continuously subjected to rubbing treatment.
  • the longitudinal direction of the long film (cellulose acylate film) was parallel to the transport direction, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was 76°.
  • the longitudinal direction of the film (transport direction) was set to 90°, and the clockwise direction was expressed as a positive value with the film width direction as the reference (0°) when observed from the film side, so that the rotation axis of the rubbing roller was at -14°.
  • the position of the rotation axis of the rubbing roller when observed from the film side is a position rotated 76° clockwise with the longitudinal direction of the film as a reference.
  • an optically anisotropic layer-forming composition (1b) containing a discotic liquid crystal compound of the following composition was applied using a Giesser coater to form a composition layer.
  • the obtained composition layer was then heated with hot air at 100°C for 2 minutes to dry the solvent and ripen the alignment of the discotic liquid crystal compound.
  • the obtained composition layer was then irradiated with UV light (500 mJ/ cm2 ) at 90°C to fix the alignment of the discotic liquid crystal compound, forming an optically anisotropic layer (1b) corresponding to the second optically anisotropic layer.
  • the optically anisotropic layer (1b) was an optically anisotropic layer X and was a negative A plate.
  • the optically anisotropic layer (1b) had a thickness of about 1.7 ⁇ m.
  • the retardation at a wavelength of 550 nm was 158 nm.
  • the average tilt angle of the discotic surface of the discotic liquid crystal compound with respect to the film surface was 90°, and it was confirmed that the compound was aligned perpendicular to the film surface.
  • the angle of the in-plane slow axis of the optically anisotropic layer (1b) was parallel to the rotation axis of the rubbing roller, and when the width direction of the film was 0° (the longitudinal direction was 90° counterclockwise and ⁇ 90° clockwise), the in-plane slow axis direction of the optically anisotropic layer (1b) was ⁇ 14° when viewed from the optically anisotropic layer (1b) side.
  • ⁇ Composition for forming optically anisotropic layer (1b) ⁇ 80 parts by weight of the following discotic liquid crystal compound 1 20 parts by weight of the following discotic liquid crystal compound 2 0.55 parts by weight of the following alignment film interface alignment agent 1 0.1 parts by weight of the following fluorine-containing compound A 0.05 parts by weight of the following fluorine-containing compound C 0.21 parts by weight of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 10 parts by weight of photopolymerization initiator (Irgacure 907, manufactured by BASF) ) 3.0 parts by mass Methyl ethyl ketone 200 parts by mass ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  • Alignment film interface alignment agent 1 Alignment film interface alignment agent 1
  • Fluorine-containing compound A (in the formula below, a and b represent the content (mass%) of each repeating unit relative to the total repeating units, a represents 90 mass% and b represents 10 mass%.
  • the weight-average molecular weight was 15,000.
  • Fluorine-containing compound B (The value in each repeating unit indicates the content (mass%) relative to the total repeating units. The weight-average molecular weight was 12,500.)
  • Fluorine-containing compound C (The value in each repeating unit indicates the content (mass%) relative to the total repeating units. The weight-average molecular weight was 12,500.)
  • a laminate (1a-1b) was produced in which an optically anisotropic layer (1a) and an optically anisotropic layer (1b) were laminated.
  • the obtained film was heated at 60°C for 1 minute with hot air, and irradiated with ultraviolet light at an irradiation dose of 100 mJ/ cm2 using a 365 nm UV-LED while purging with nitrogen so that the atmosphere had an oxygen concentration of 100 ppm by volume or less. Thereafter, the obtained coating film was annealed with hot air at 120°C for 1 minute to form an optically anisotropic layer (1d) corresponding to the fourth optically anisotropic layer.
  • the obtained optically anisotropic layer (1d) was irradiated with 7.9 mJ/ cm2 (wavelength: 313 nm) of UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) through a wire grid polarizer at room temperature to form a composition layer having alignment control ability on the surface.
  • the thickness of the optically anisotropic layer (1d) thus formed was 0.7 ⁇ m.
  • the in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction at a wavelength of 550 nm was ⁇ 88 nm.
  • the average tilt angle of the long axis direction of the rod-like liquid crystal compound with respect to the film surface was 90°, and it was confirmed that the compound was aligned perpendicular to the film surface.
  • ⁇ Optically anisotropic layer forming composition (1d) ⁇ Rod-shaped liquid crystal compound (A) shown below: 100 parts by weight Polymerizable monomer (A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.) 4.0 parts by weight Polymerization initiator S-1 (oxime type) shown below: 5.0 parts by weight Photoacid generator D-1 3.0 parts by weight Polymer M-1 shown below 2.0 parts by weight Vertical alignment agent S01 shown below 2.0 parts by weight Photoalignment polymer A-1 shown below 2.0 parts by weight Methyl ethyl ketone 42.3 parts by mass Methyl isobutyl ketone 627.5 parts by mass ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  • Rod-shaped liquid crystal compound (A) (hereinafter, a mixture of compounds)
  • Polymer M-1 (The numerical value in each repeating unit indicates the content (mass%) relative to the total repeating units. The weight average molecular weight was 58,000.)
  • Photoalignable polymer A-1 (The numerical value in each repeating unit indicates the content (mass%) of each repeating unit relative to the total repeating units. The weight-average molecular weight was 69,800.)
  • the thickness of the optically anisotropic layer (1c) was 1.2 ⁇ m, ⁇ nd at a wavelength of 550 nm was 173 nm, and the twist angle of the liquid crystal compound was 84°.
  • the in-plane slow axis direction (the alignment axis angle of the liquid crystal compound) was 11° on the air side and 95° on the side in contact with the optically anisotropic layer (1d), assuming that the width direction of the film is 0° (the longitudinal direction is 90°).
  • the in-plane slow axis direction of the optically anisotropic layer is expressed as negative when rotated clockwise (right-handed) and positive when rotated counterclockwise (left-handed), with the width direction of the substrate taken as the reference 0°, when observing the substrate from the surface side of the optically anisotropic layer.
  • composition for forming an optically anisotropic layer (1c) The above-mentioned rod-shaped liquid crystal compound (A) 100 parts by weight Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by weight Photopolymerization initiator (Irgacure 819, manufactured by BASF) 3 parts by weight 0.60 parts by mass of the left-handed twisted chiral agent (L1) above 0.08 parts by mass of the above fluorine-containing compound C 156 parts by mass ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  • a laminate (1c-1d) was produced in which the optically anisotropic layer (1d) and the optically anisotropic layer (1c) were directly laminated on a long cellulose acylate film.
  • the surface side of the optically anisotropic layer (1b) formed on the optically anisotropic layer (1a) made of the long-sized cellulose acylate film prepared above and the surface side of the optically anisotropic layer (1c) of the laminate (1c-1d) formed on the long-sized cellulose acylate film prepared above were continuously bonded together via an adhesive A (product name: SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.) having a thickness of about 20 ⁇ m so that the angle between the in-plane slow axis of the optically anisotropic layer (1b) and the in-plane slow axis of the surface side of the optically anisotropic layer (1c) was 3°.
  • an adhesive A product name: SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.
  • the cellulose acylate film as the optically anisotropic layer (1a) and the rubbing-treated alignment film were peeled off to expose the surface of the optically anisotropic layer (1b) that had been in contact with the cellulose acylate film.
  • an optical film (1d-1c-1b) was obtained in which the optically anisotropic layer (1d), the optically anisotropic layer (1c), and the optically anisotropic layer (1b) were laminated in this order on the long cellulose acylate film.
  • the support surface of a cellulose triacetate film TJ25 (manufactured by Fujifilm Corporation: thickness 25 ⁇ m) was subjected to an alkali saponification treatment. Specifically, the support was immersed in a 1.5N sodium hydroxide aqueous solution at 55° C. for 2 minutes, and then washed in a water washing bath at room temperature, and further neutralized with 0.1N sulfuric acid at 30° C. After neutralization, the support was washed in a water washing bath at room temperature, and further dried with hot air at 100° C. to obtain a polarizer protective film.
  • a rolled polyvinyl alcohol (PVA) film having a thickness of 60 ⁇ m was continuously stretched in the longitudinal direction in an iodine aqueous solution and dried to obtain a polarizer having a thickness of 13 ⁇ m.
  • the luminosity-corrected single transmittance of the polarizer was 43%.
  • the absorption axis direction of the polarizer coincided with the longitudinal direction.
  • the above polarizer protective film was attached to one surface of the above polarizer using the following PVA adhesive to prepare a linear polarizing plate.
  • PVA adhesive was prepared by dissolving 100 parts by mass of a polyvinyl alcohol resin having acetoacetyl groups (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: 5 mol%) and 20 parts by mass of methylol melamine in pure water at a temperature of 30°C to give an aqueous solution with a solids concentration of 3.7% by mass.
  • a circular polarizing plate (P1) consisting of the optical film (1d-1c-1b) and the linear polarizing plate was prepared.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (1b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (1b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • Example 2 (Formation of Optically Anisotropic Layer (2a))
  • a long cellulose acylate film was prepared, and an optically anisotropic layer-forming composition (2a) containing a discotic liquid crystal compound having the following composition was applied onto the cellulose acylate film using a Giesser coater to form a composition layer.
  • the film on which the composition layer was formed was heated with hot air at 116°C for 1 minute, and irradiated with ultraviolet light at an irradiation dose of 150 mJ/ cm2 using a 365 nm UV-LED while purging with nitrogen so that the atmosphere had an oxygen concentration of 100 volume ppm or less at a temperature of 95°C.
  • the resulting coating film was annealed with hot air at 115°C for 25 seconds to form an optically anisotropic layer (2a) corresponding to the first optically anisotropic layer.
  • the optically anisotropic layer (2a) was an optically anisotropic layer Y and a negative C plate.
  • the obtained optically anisotropic layer (2a) was irradiated with 7.9 mJ/ cm2 (wavelength: 313 nm) of UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) through a wire grid polarizer at room temperature to obtain a long film 1 having an orientation control ability imparted to the surface of the optically anisotropic layer (2a).
  • the thickness of the optically anisotropic layer (2a) formed was 0.7 ⁇ m.
  • the in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction at a wavelength of 550 nm was 35 nm.
  • the average tilt angle of the discotic surface of the discotic liquid crystal compound with respect to the film surface was 0°, and it was confirmed that the compound was aligned horizontally with respect to the film surface.
  • ⁇ Composition for forming an optically anisotropic layer (2a) ⁇ 4 parts by weight of the following discotic liquid crystal compound 1 1 part by weight of the following discotic liquid crystal compound 2 95.0 parts by weight of the following discotic liquid crystal compound 3 12.0 parts by weight of the following polymerizable monomer 1 Polymerization initiator S- Photoacid generator D-1 (oxime type) 3.0 parts by weight Photoalignable polymer A-1 (see below) 0.6 parts by weight Diisopropylethylamine 0.2 parts by weight o-xylene 475 parts by weight Club------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  • Photoalignable polymer A-1 (The alphabet in each repeating unit indicates the content (mass%) of each repeating unit relative to the total repeating units, a and b were 53 mass% and 47 mass%, respectively. The weight average molecular weight was 183,000.)
  • an optically anisotropic layer-forming composition (2b) containing a discotic liquid crystal compound of the following composition was applied onto the optically anisotropic layer (2a) using a Giesser coater, and the layer was heated for 120 seconds with hot air at 100° C. Subsequently, the obtained composition layer was irradiated with UV (100 mJ/cm 2 ) at 90° C. to fix the orientation of the liquid crystal compound, thereby forming an optically anisotropic layer (2b) (corresponding to a negative A plate) corresponding to the second optically anisotropic layer.
  • the optically anisotropic layer (2b) corresponds to the optically anisotropic layer X and was a negative A plate.
  • the optically anisotropic layer (2b) had a thickness of about 1.7 ⁇ m and an in-plane retardation of 158 nm at a wavelength of 550 nm.
  • the average inclination angle of the discotic plane of the discotic liquid crystal compound with respect to the film plane was 90°, and it was confirmed that the compound was aligned perpendicular to the film plane.
  • the in-plane slow axis direction of the optically anisotropic layer (2b) is ⁇ 14° when viewed from the optically anisotropic layer (2b) side.
  • Alignment film interface alignment agent 1 Alignment film interface alignment agent 1
  • Fluorine-containing compound D (The value in each repeating unit indicates the content relative to the total repeating units. The weight-average molecular weight was 12,500.)
  • Fluorine-containing compound E (The value in each repeating unit indicates the content relative to the total repeating units. The weight-average molecular weight was 12,500.)
  • the optically anisotropic layer (2a) and the optically anisotropic layer (2b) were directly laminated on the long cellulose acylate film, and a laminate film (2a-2b) was obtained that was wound into a roll.
  • the surface side of the optically anisotropic layer (2b) of the laminate (2a-2b) formed on the long cellulose acylate film prepared above and the surface side of the optically anisotropic layer (1c) of the laminate (1c-1d) formed on the long cellulose acylate film prepared in Example 1 were continuously bonded together via an adhesive A (product name: SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.) having a thickness of about 20 ⁇ m so that the angle between the in-plane slow axis of the optically anisotropic layer (2b) and the in-plane slow axis of the surface side of the optically anisotropic layer (1c) was 3°.
  • an adhesive A product name: SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.
  • the cellulose acylate film on the optically anisotropic layer (2a) side was peeled off to expose the surface of the optically anisotropic layer (2a) that had been in contact with the cellulose acylate film.
  • an optical film (2a-2b-1c-1d) was obtained in which the optically anisotropic layer (1d), the optically anisotropic layer (1c), the optically anisotropic layer (2b), and the optically anisotropic layer (2a) were laminated in this order on the long cellulose acylate film.
  • a circular polarizing plate (P2) consisting of the optical film (2a-2b-1c-1d) and a linear polarizing plate was prepared.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (2a), the optically anisotropic layer (2b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (2b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (2b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (2b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • Example 3 (Formation of Optically Anisotropic Layer (3b)) An optically anisotropic layer (3b) was formed in the same manner as in Example 2, except that the temperature during UV irradiation in the preparation of the optically anisotropic layer (2b) was 100° C. and the film thickness was changed.
  • the optically anisotropic layer (3b) had a thickness of about 2.0 ⁇ m and an in-plane retardation of 158 nm at a wavelength of 550 nm.
  • the average inclination angle of the discotic plane of the discotic liquid crystal compound with respect to the film plane was 90°, and it was confirmed that the compound was aligned perpendicular to the film plane.
  • the in-plane slow axis direction of the optically anisotropic layer (3b) is ⁇ 14° when viewed from the optically anisotropic layer (3b) side.
  • a circular polarizing plate (P3) consisting of an optical film (2a-3b-1c-1d) and a linear polarizing plate was prepared in the same manner as in Example 2.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (2a), the optically anisotropic layer (3b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (3b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (3b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (3b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the polarizer absorption axis and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • Example 4 (Formation of Optically Anisotropic Layer (4b)) An optically anisotropic layer (4b) was formed in the same manner as in Example 2, except that in the preparation of the optically anisotropic layer (2b), a composition for forming an optically anisotropic layer (4b) using Lumiplus LPK-2000 manufactured by Mitsubishi Gas Chemical Company, Inc. was used instead of the polymerizable monomer 1, and the film thickness was changed.
  • the optically anisotropic layer (4b) had a thickness of about 2.0 ⁇ m and an in-plane retardation of 158 nm at a wavelength of 550 nm.
  • the average tilt angle of the discotic plane of the discotic liquid crystal compound with respect to the film plane was 90°, and it was confirmed that the compound was aligned perpendicular to the film plane.
  • the width direction of the film is 0° (the longitudinal direction is 90° counterclockwise and ⁇ 90° clockwise)
  • the in-plane slow axis direction of the optically anisotropic layer (4b) is ⁇ 14° when viewed from the optically anisotropic layer (4b) side.
  • composition for forming an optically anisotropic layer (4b) The above discotic liquid crystal compound 1: 80 parts by weight The above discotic liquid crystal compound 2: 20 parts by weight The above alignment film interface alignment agent 1: 1.8 parts by weight Lumiplus LPK-2000: 15.0 parts by weight The above polymerization initiator S-1 (Oxime type) 5.0 parts by mass of the above fluorine-containing compound A 0.1 parts by mass of the above fluorine-containing compound D 0.21 parts by mass of the above fluorine-containing compound E 0.06 parts by mass of the above defoamer 1 2. 1 part by mass Methyl ethyl ketone 299 parts by mass ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  • a circular polarizing plate (P4) consisting of an optical film (2a-4b-1c-1d) and a linear polarizing plate was prepared in the same manner as in Example 2.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (2a), the optically anisotropic layer (4b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (4b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (4b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (4b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • Example 5 (Formation of Optically Anisotropic Layer (5a)) An optically anisotropic layer (5a) was formed in the same manner as in Example 2, except that in the preparation of the optically anisotropic layer (2a), the temperature during UV irradiation was set to 100° C. and the film thickness was changed. The thickness of the optically anisotropic layer (5a) thus formed was about 0.9 ⁇ m.
  • the in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction at a wavelength of 550 nm was 35 nm.
  • the average tilt angle of the discotic surface of the discotic liquid crystal compound with respect to the film surface was 0°, and it was confirmed that the compound was aligned horizontally with respect to the film surface.
  • a circular polarizing plate (P5) consisting of an optical film (5a-2b-1c-1d) and a linear polarizing plate was prepared in the same manner as in Example 2.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (5a), the optically anisotropic layer (2b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (2b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (2b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (2b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • Example 6 (Formation of Optically Anisotropic Layer (5a)) An optically anisotropic layer (5a) was formed in the same manner as in Example 5.
  • a circular polarizing plate (P6) consisting of an optical film (5a-3b-1c-1d) and a linear polarizing plate was prepared in the same manner as in Example 2.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (5a), the optically anisotropic layer (3b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (3b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (3b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (3b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • Example 7 (Formation of Optically Anisotropic Layer (7a)) An optically anisotropic layer (7a) was formed in the same manner as in Example 2, except that the temperature during UV irradiation was 90° C. in the preparation of the optically anisotropic layer (2a). The thickness of the optically anisotropic layer (7a) thus formed was about 0.7 ⁇ m.
  • the in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction at a wavelength of 550 nm was 35 nm.
  • the average tilt angle of the discotic surface of the discotic liquid crystal compound with respect to the film surface was 0°, and it was confirmed that the compound was aligned horizontally with respect to the film surface.
  • a circular polarizing plate (P7) consisting of an optical film (7a-2b-1c-1d) and a linear polarizing plate was prepared in the same manner as in Example 2.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (7a), the optically anisotropic layer (2b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (2b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (2b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (2b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • Example 8 (Formation of Optically Anisotropic Layer (8a)) An optically anisotropic layer (8a) was formed in the same manner as in Example 2, except that the thickness of the optically anisotropic layer (2a) was changed. The thickness of the optically anisotropic layer (8a) thus formed was 0.6 ⁇ m.
  • the in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction at a wavelength of 550 nm was 35 nm.
  • the average tilt angle of the discotic surface of the discotic liquid crystal compound with respect to the film surface was 0°, and it was confirmed that the compound was aligned horizontally with respect to the film surface.
  • a circular polarizing plate (P8) consisting of an optical film (8a-2b-1c-1d) and a linear polarizing plate was prepared in the same manner as in Example 2.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (8a), the optically anisotropic layer (2b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (2b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (2b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (2b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • optically anisotropic layer (9b) was formed in the same manner as in Example 2, except that the temperature during UV irradiation was 80° C. in the preparation of the optically anisotropic layer (2b).
  • the optically anisotropic layer (9b) had a thickness of about 1.4 ⁇ m and an in-plane retardation of 158 nm at a wavelength of 550 nm.
  • the average inclination angle of the discotic plane of the discotic liquid crystal compound with respect to the film plane was 90°, and it was confirmed that the compound was aligned perpendicular to the film plane.
  • the in-plane slow axis direction of the optically anisotropic layer (9b) is ⁇ 14° when viewed from the optically anisotropic layer (9b) side.
  • a circular polarizing plate (P9) consisting of an optical film (9a-9b-1c-1d) and a linear polarizing plate was prepared in the same manner as in Example 2.
  • the polarizer protective film, the polarizer, the optically anisotropic layer (9a), the optically anisotropic layer (9b), the optically anisotropic layer (1c) and the optically anisotropic layer (1d) were laminated in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (9b) was 76°.
  • the angle between the in-plane slow axis of the optically anisotropic layer (9b) and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (9b) side was 3°.
  • the twist angle of the liquid crystal compound of the optically anisotropic layer (1c) was 84°.
  • the angle between the polarizer absorption axis and the in-plane slow axis of the optically anisotropic layer (1c) on the surface of the optically anisotropic layer (1d) side was 5°.
  • ⁇ Film thickness measurement> The thickness of the optically anisotropic layer was measured using a reflection spectroscopic film thickness meter FE3000 (manufactured by Otsuka Electronics Co., Ltd.).
  • ⁇ Measurement of refractive index> The complex reflectance at incident angles of 50 to 70° obtained by ellipsometry was analyzed using an optical model that took into account the anisotropy of the refractive index to obtain ne and no of the optically anisotropic layer, and the refractive index anisotropy ⁇ n was calculated from the obtained ne and no.
  • the refractive index in the transmission axis direction of the polarizer was calculated from the obtained ne and no. For example, when the transmission axis direction of the polarizer is a position shifted by x degrees from ne, the refractive index nT in the transmission axis direction is calculated from the following formula.
  • nT ne*(cosx)/(cosx+sinx)+no*(sinx)/(cosx+sinx)
  • the refractive index is measured at a wavelength of 550 nm.
  • the measuring device used may be a Woollam RC2 or a Semilab SE-2000. Further, for the adjacent layer X and the adjacent layer Y, the refractive index in the transmission axis direction of the polarizer was calculated according to the same procedure as above.
  • the column “angle” in the column “optically anisotropic layer X” indicates the angle between the transmission axis of the polarizer and the in-plane slow axis of the optically anisotropic layer X.
  • the polarizing plate of the present invention exhibited the desired effects.
  • Example 1 By comparing Example 1 with the other Examples, it was confirmed that when the polarizing plate had the optically anisotropic layer Y, the effect was more excellent.
  • Example 7 By comparing Example 7 with other Examples, it was confirmed that when the difference between the refractive index of the optically anisotropic layer Y and the refractive index of the adjacent layer Y is within a predetermined range, the effect is more excellent.
  • Example 8 it was confirmed that when the optically anisotropic layer Y had a predetermined thickness, the effect was superior.

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Citations (8)

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JP2015068847A (ja) * 2013-09-26 2015-04-13 大日本印刷株式会社 偏光板、画像表示装置、および画像表示装置における明所コントラストの改善方法
JP2016200817A (ja) * 2015-04-10 2016-12-01 東洋紡株式会社 液晶表示装置
JP2020034950A (ja) * 2014-10-30 2020-03-05 東洋紡株式会社 液晶表示装置及び偏光板
JP2021039275A (ja) * 2019-09-04 2021-03-11 日東電工株式会社 積層光学フィルムおよび画像表示装置
JP2021051316A (ja) * 2014-09-17 2021-04-01 日本ゼオン株式会社 円偏光板、広帯域λ／４板、及び、有機エレクトロルミネッセンス表示装置
WO2021261276A1 (ja) * 2020-06-26 2021-12-30 日東電工株式会社 偏光板、位相差層付偏光板および画像表示装置
JP2022184691A (ja) * 2021-06-01 2022-12-13 富士フイルム株式会社 位相差フィルム、円偏光板、表示装置
JP2023084440A (ja) * 2021-12-07 2023-06-19 富士フイルム株式会社 積層フィルム、円偏光板、表示装置

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015068847A (ja) * 2013-09-26 2015-04-13 大日本印刷株式会社 偏光板、画像表示装置、および画像表示装置における明所コントラストの改善方法
JP2021051316A (ja) * 2014-09-17 2021-04-01 日本ゼオン株式会社 円偏光板、広帯域λ／４板、及び、有機エレクトロルミネッセンス表示装置
JP2020034950A (ja) * 2014-10-30 2020-03-05 東洋紡株式会社 液晶表示装置及び偏光板
JP2016200817A (ja) * 2015-04-10 2016-12-01 東洋紡株式会社 液晶表示装置
JP2021039275A (ja) * 2019-09-04 2021-03-11 日東電工株式会社 積層光学フィルムおよび画像表示装置
WO2021261276A1 (ja) * 2020-06-26 2021-12-30 日東電工株式会社 偏光板、位相差層付偏光板および画像表示装置
JP2022184691A (ja) * 2021-06-01 2022-12-13 富士フイルム株式会社 位相差フィルム、円偏光板、表示装置
JP2023084440A (ja) * 2021-12-07 2023-06-19 富士フイルム株式会社 積層フィルム、円偏光板、表示装置

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