Optical laminate and organic el display device

Abstract

Provided is an optical laminate capable of suppressing changes in black display ability due to reflection of external light in an image display device to which the optical laminate is applied, and capable of imparting good black display ability to the same degree as in a front direction when the image display device is observed from an oblique direction. An optical laminate (100) includes a polarizing film (10), an A plate (21), and a first C plate (20), and the angle between the absorption axis of the polarizing film (10) and the slow axis of the A plate (21) is about 45°. The rate of change in the visibility correction reflectance of the optical laminate (100) when attached to a light-reflecting layer (17) is less than 15%.

Description

[0001] This application is a divisional application, whose parent application application number is 202080016204.8 (PCT / JP2020 / 002320), application date is January 23, 2020, and invention title is: Optical Laminate and Organic EL Display Device. Technical Field

[0002] This invention relates to optical laminates and organic EL display devices. Background Technology

[0003] In recent years, image display devices, represented by organic electroluminescent (OLED) displays, have been rapidly gaining popularity. OLED displays incorporate a circular polarizer equipped with a polarizing film and a phase retardation film (λ / 4 plate, phase retardation value approximately 140nm). By configuring the circular polarizer, reflection of incoming light can be prevented, improving image visibility. The display device's ability to prevent reflection of incoming light is directly related to its performance in displaying black as its true black. The higher this performance, the higher the contrast ratio of the display device.

[0004] A circular polarizer can be obtained by combining a polarizing film with an A-plate (λ / 4 plate, phase difference value of approximately 140 nm) (see, for example, Patent Document 1). The phase difference value of the A-plate differs in appearance when viewed from an oblique direction and when viewed from the front. Therefore, there is a problem that the intensity of reflected light changes depending on the direction of the viewing image, and the black level of the display device changes with the angle.

[0005] To compensate for changes in phase difference that depend on the orientation of the viewed image, a scheme involving further combining the C-plate has been proposed. Previous understanding held that the stacking order of the A-plate and C-plate was arbitrary, regardless of the characteristics of the combined light-reflecting layers. However, a display device equipped with a circular polarizer having a phase difference film designed to match the characteristics of the light-reflecting layers cannot necessarily be considered a display device that achieves black display capability independent of the orientation of the viewed image.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2016-40603 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] To ensure the optimal stacking order of the polarizing film, A-plate, and C-plate when placing a circular polarizing plate on an ideal specular reflective layer and achieving uniform reflectivity of incoming light when changing the in-plane azimuth angle in a tilted field of view, the polarizing film, A-plate, and C-plate are necessary. This can be confirmed by performing polarization propagation analysis using the Mueller matrix.

[0011] If a circular polarizing plate with a polarizing film and an A-plate is placed on an ideal specular reflective layer, the phase difference of the A-plate changes with the observation angle of the in-plane azimuth. Therefore, when the angle between the slow axis of the A-plate and the observer's line of sight is approximately 45°, the phase difference change reaches a minimum, resulting in a minimum reflectivity; this observation angle is called the minimum reflectivity angle. Conversely, when the angle between the slow axis of the A-plate and the observer's line of sight is approximately 90° or 0°, the phase difference change reaches a maximum, resulting in a maximum reflectivity; this observation angle is called the maximum reflectivity angle.

[0012] The stacking order of the polarizing film, C-plate, and A-plate, as in the case of a polarizing film, C-plate, A-plate, and C-plate, is theoretically not ideal. Specifically, the reflected light after entering the circular polarizing film and being reflected by the reflective layer, passing through the A-plate, becomes linearly polarized. At the maximum reflectivity angle, the vibrational electric field direction of the linearly polarized light exiting the A-plate forms an angle of approximately 45° with the observer's line of sight. Since the slow axis of the C-plate is parallel to the observer's line of sight, the angle between the vibrational electric field direction of the linearly polarized light exiting the A-plate and the slow axis of the C-plate is approximately 45°. At this point, the light entering the polarizing film, observed at the maximum reflectivity angle, becomes elliptically polarized. The polarization component of the reflected light, orthogonal to the absorption axis of the polarizing film, is not absorbed and is transmitted. Adding this increase in reflectivity to the increase in reflectivity due to the change in the phase difference of the A-plate based on the aforementioned observation angle yields the maximum reflectivity value. On the other hand, the angle between the direction of the vibrating electric field of the linearly polarized light emitted from plate A and the slow axis of plate C is approximately 0°, and the change in reflectivity is only the increase in reflectivity caused by the change in the phase difference of plate A based on the aforementioned observation angle. As a result, the rate of change from the reflectivity minimum to the reflectivity maximum becomes larger.

[0013] Research is underway on the use of highly light-diffusing reflective layers in organic EL displays. It has been clarified that in such organic EL displays, contrary to calculations for an ideal mirror, the desired stacking order of polarizing film, C-plate, A-plate, or polarizing film, C-plate, A-plate, C-plate, is that the C-plate is positioned between the polarizing film and the A-plate. This is because, due to the diffuse reflection of the reflective layer, the angular resolution at each observation angle decreases, resulting in the overlap of reflected light at the respective observation angles of the minimum and maximum reflectivity angles calculated for an ideal mirror, leading to the averaging of the minimum and maximum values. That is, compared to the ideal mirror case, the minimum reflectivity increases, and the maximum reflectivity decreases. Consequently, if a highly light-diffusing reflective layer is applied with the C-plate positioned between the polarizing film and the A-plate, the rate of change of reflectivity when the azimuth angle is altered becomes smaller.

[0014] The purpose of this invention is to provide an optical laminate that can suppress changes in black display capability caused by external light reflection in an image display device using the optical laminate, and can also provide the same level of good black display capability as in the front view when the image display device is viewed from an oblique direction, and to provide an organic EL display device equipped with the optical laminate.

[0015] means for solving problems

[0016] The present invention provides an optical laminate comprising a polarizing film, an A plate, and a first C plate, wherein the angle between the absorption axis of the polarizing film and the slow axis of the A plate is approximately 45°, and the rate of change of visibility-corrected reflectivity when attached to a light-reflecting layer is less than 15%.

[0017] In an image display device using an optical laminate constructed as described above, variations in black level caused by external light reflection can be suppressed, and the image display device can be given the same level of good black level as when viewed from an oblique direction.

[0018] The optical laminate of the present invention may sequentially include a polarizing film, a first C plate, and an A plate.

[0019] In addition, the optical laminate of the present invention may be an optical laminate with a scattering half-value angle of 10° or more for the light reflecting layer and satisfying the following formulas (i) and (ii).

[0020] 135nm<ROA(550)<150nm...(i)

[0021] -100nm≤R th C1(550)≤0nm...(ii)

[0022] [In the above formula, R0A(550) represents the in-plane phase difference value of plate A at a wavelength of 550nm, Rth C1(550) represents the phase difference along the thickness direction of the first C plate at a wavelength of 550 nm.

[0023] In addition, the optical laminate of the present invention may further include a second C plate, and sequentially include a polarizing film, a first C plate, an A plate, and a second C plate.

[0024] In addition, the optical laminate of the present invention may be an optical laminate with a scattering half-value angle of 10° or more for the light reflecting layer and satisfying the following formulas (iii), (iv) and (y).

[0025] 135nm<ROA(550)<150nm...(iii)

[0026] -100nm≤R th C1(550)<R th C2(550)≤0nm...(iv)

[0027] -100nm≤R th C1(550)+R th C2(550)...(v)

[0028] [In the above formula, R0A(550) represents the in-plane phase difference value of plate A at a wavelength of 550nm, R th C1(550) represents the phase difference value along the thickness direction of the first C plate at a wavelength of 550 nm, R th C2(550) represents the phase difference along the thickness direction of the second C plate at a wavelength of 550 nm.

[0029] In addition, the optical laminate of the present invention can be an optical laminate with a scattering half-value angle of less than 10° of the light reflecting layer and satisfying the following formulas (iii), (vi) and (vii).

[0030] 135nm<ROA(550)<150nm...(iii)

[0031] -100nm≤R th C2(550)<R th C1(550)≤0nm...(vi)

[0032] -100nm≤R th C1(550)+R th C2(550)...(vii)

[0033] [In the above formula, R0A(550) represents the in-plane phase difference value of plate A at a wavelength of 550nm, R th C1(550) represents the phase difference value along the thickness direction of the first C plate at a wavelength of 550 nm, Rth C2(550) represents the phase difference along the thickness direction of the second C plate at a wavelength of 550 nm.

[0034] In addition, the optical laminate of the present invention may be an optical laminate that satisfies the following formula (viii).

[0035] 0.80<R0A(450) / R0A(550)<0.93...(viii)

[0036] [In the above formula, R0A(450) represents the in-plane phase difference of plate A at a wavelength of 450nm, and R0A(550) represents the in-plane phase difference of plate A at a wavelength of 550nm.]

[0037] Furthermore, the present invention provides an organic EL display device comprising a light-reflecting layer and any one of the aforementioned optical layers. In this case, it is preferable to combine plate A and plate C as described above, depending on whether the scattering half-value angle is 10° or more or less than 10°.

[0038] Invention Effects

[0039] According to the present invention, an optical laminate can be provided that can suppress changes in black display capability caused by external light reflection in an image display device in which it is applied, and can also provide the same level of good black display capability as in the front view when the image display device is viewed from an oblique direction, and can provide an organic EL display device having the optical laminate. Attached Figure Description

[0040] Figure 1 This is a cross-sectional view of an optical laminate according to one embodiment of the present invention.

[0041] Figure 2 (A) and (B) are both schematic diagrams used to illustrate the measurement of the rate of change of visibility-corrected reflectance. Detailed Implementation

[0042] Hereinafter, suitable embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0043] <Optical laminate>

[0044] like Figure 1 As shown, in one embodiment of the optical laminate (hereinafter also simply referred to as "laminated laminate") 100, there are a polarizing plate 1 with a protective film 11 laminated on one side of the polarizing film 10, and a phase retardation film 2. The polarizing plate 1 and the phase retardation film 2 are laminated via an adhesive layer 13 such that the polarizing film 10 and the phase retardation film 2 face each other. Figure 1 The image shows the laminate 100 being bonded to the light-reflecting layer 17 via the adhesive layer 14. It should be noted that... Figure 1 The adhesive layer used to bond the polarizing film 10 and the protective film 11 is not shown in the figure.

[0045] The retardation film 2, starting from the side closest to the polarizing film 10, sequentially comprises a first C plate 20, an A plate 21, and a second C plate 22. The first C plate 20 and the A plate 21 are laminated via an adhesive layer 15, and the A plate 21 and the second C plate 22 are laminated via an adhesive layer 16. Furthermore, the retardation film may, in addition to the A plate, the first C plate, and the second C plate, also include, for example, an alignment film for orienting the polymerizable liquid crystal compound, a substrate film, and other retardation layers. These will be described later. It should be noted that, as another embodiment, it may be configured to omit either the first C plate 20 or the second C plate 22. Alternatively, it may be configured to have protective films 11 laminated on both sides of the polarizing film 10.

[0046] The light-reflecting layer 17 may be, for example, an electrode found in an organic EL display element. In this case, at least one layer selected from transparent or semi-transparent electrodes, hole injection layers, hole transport layers, organic light-emitting layers, hole prevention layers, electron transport layers, and electron injection layers may be provided between the light-reflecting layer 17 and the retardation film.

[0047] The optimal phase difference between plate 1C 20 and plate 2C 22 and their magnitude relationship vary with the scattering and reflection half-value angle of the light-reflecting layer. This will be described later in "(4) Relationship with the light-reflecting layer" of "<Phase Difference Film>".

[0048] The laminate 100 can have Figure 1 Layers other than the layer shown. Further layers that can be included in the laminate include a front panel, a light-shielding pattern, and a touch sensor. The front panel can be disposed on the side of the polarizer opposite to the side where the retardation film is laminated. The light-shielding pattern can be disposed between the front panel and the laminate. The light-shielding pattern can be formed on the surface of the front panel on the polarizer side. The light-shielding pattern is formed on the bezel (non-display area) of the image display device, making the wiring of the image display device invisible to the user. The touch sensor can be disposed between the front panel and the laminate, between the retardation film of the laminate and the light-reflecting layer, etc.

[0049] The shape of the laminate 100 is not particularly limited. When the laminate 100 is substantially rectangular, the length of the long side is preferably 5 cm or more and 35 cm or less, more preferably 10 cm or more and 25 cm or less, and the length of the short side is preferably 5 cm or more and 25 cm or less, more preferably 6 cm or more and 20 cm or less.

[0050] The term "substantially rectangular" means that the laminate 100 can be: a shape in which at least one of the four corners (corners) of the main surface is cut off at an obtuse angle or has an arc, or has a recess (notch) in which a portion of the end face perpendicular to the main surface is recessed inward, or has an opening in the main surface that is hollowed out in the shape of a circle, ellipse, polygon, or combination thereof.

[0051] In this embodiment, the rate of change of visibility-corrected reflectivity when the laminate is attached to the light-reflecting layer is less than 15%, more preferably less than 14%. The lower limit of the rate of change of visibility-corrected reflectivity is not particularly limited; however, ideally it is 0%, but it can also be 5% or more. If the rate of change of visibility-corrected reflectivity is of this value, the reflectivity of the reflected light from the organic EL display device can be made more uniform.

[0052] In this specification, the rate of change of visibility-corrected reflectance refers to the rate of change between the visibility-corrected reflectance Ymax at the in-plane angle where the visibility-corrected reflectance reaches its maximum, and the visibility-corrected reflectance Ymin at that in-plane angle plus 90°, when viewed from a 50° elevation angle with the organic EL display device in black mode. The in-plane angle at which the visibility-corrected reflectance reaches its maximum is defined as the angle at which the visibility-corrected reflectance reaches its maximum, measured by setting the elevation angle to 50° and changing the in-plane angle from 0° to 360°.

[0053] Specifically, refer to Figure 2 The rate of change of visibility-corrected reflectance is explained. Figure 2 (A) is a view of the laminate 100 from the side. The visibility-corrected reflectance value used to calculate the rate of change of visibility-corrected reflectance is the value when viewed from a direction 40 with an elevation angle of 30° to 50°. Figure 2 (B) is a view of the laminate 100 as seen from above (from the side opposite to the phase difference film, with the polarizing film as a reference). The rate of change of visibility-corrected reflectance is calculated by measuring the visibility-corrected reflectance value when viewed from direction 41 where the visibility-corrected reflectance value reaches its maximum, and the visibility-corrected reflectance value when viewed from direction 42 where the in-plane angle of direction 41 is increased by 90° (in-plane angle 32).

[0054] Rate of change of visibility-corrected reflectance = (Ymax - Ymin) / Ymax

[0055] The visibility-corrected reflectance is calculated using the reflectance spectrophotometer R(λ), isochromatic function y(λ), and CIE standard illuminant D65 emission spectrophotometer S(λ) measured in SCI (Specular Component Include) mode within the measurement wavelength range λ, according to the following formula. The measurement wavelength range λ is from 380 mm to 780 mm.

[0056] Visibility-corrected reflectance = ∑(R(λ)×y(λ)×S(λ)) / ∑(y(λ)×S(λ))

[0057] The visibility-corrected reflectance Ymax, which is the in-plane angle at which the visibility-corrected reflectance reaches its maximum, is preferably 4.0% or more and 6.0% or less, more preferably 4.0% or more and 5.0% or less. Furthermore, the visibility-corrected reflectance Ymin, which is the in-plane angle plus 90°, is preferably 4.0% or more and 6.0% or less, more preferably 4.0% or more and 5.0% or less.

[0058] <Polarizing plate>

[0059] In this embodiment, a polarizing plate refers to a film formed by a polarizing film and a protective film adhered to one or both sides of the polarizing film. The protective film of the polarizing plate may have surface treatment layers such as a hard coating, an anti-reflective layer, or an antistatic layer, as described later. The polarizing film and the protective film may be laminated, for example, via an adhesive layer or a bonding agent layer. The components of the polarizing plate are described below.

[0060] (1) Polarizing film

[0061] The polarizing film of the polarizing plate can be an absorption-type polarizing film with the property that it absorbs linearly polarized light having a vibration plane parallel to its absorption axis and transmits linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis). As a polarizing film, a polarizing film in which dichroic dyes are adsorbed onto a uniaxially stretched polyvinyl alcohol-based resin film and oriented accordingly can be used. The polarizing film can be manufactured, for example, by a method including the following steps: uniaxially stretching the polyvinyl alcohol-based resin film; adsorbing the dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye; treating the polyvinyl alcohol-based resin film with the adsorbed dichroic dye using a crosslinking solution such as a boric acid aqueous solution; and washing with water after treatment with the crosslinking solution.

[0062] As a polyvinyl alcohol-based resin, a resin obtained by saponifying a polyvinyl acetate-based resin can be used. In addition to polyvinyl acetate as a homopolymer of vinyl acetate, examples of polyvinyl acetate-based resins include copolymers of vinyl acetate with other monomers that can be copolymerized. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides containing ammonium groups.

[0063] In this specification, "(meth)acrylic acid" refers to at least one selected from acrylic acid and methacrylic acid. The same applies to "(meth)acryloyl" and "(meth)acrylate".

[0064] The saponification degree of polyvinyl alcohol (PVA) resins is typically 85–100 mol%, preferably 98 mol% or higher. PVA resins can be modified; for example, aldehyde-modified PVA formal or PVA acetal can be used. The average degree of polymerization of PVA resins is typically 1000–10000, preferably 1500–5000. The average degree of polymerization of PVA resins can be determined according to JIS K 6726.

[0065] The film obtained by forming this polyvinyl alcohol-based resin is used as the base film for polarizing films. The method for forming the polyvinyl alcohol-based resin film is not particularly limited, and known methods can be used. The thickness of the polyvinyl alcohol-based base film is not particularly limited; however, in order to set the thickness of the polarizing film to 15 μm or less, a base film of 5 to 35 μm is preferred. More preferably, it is 20 μm or less.

[0066] Uniaxial stretching of polyvinyl alcohol (PVA) resin films can be performed before, during, or after dyeing with dichroic pigments. When uniaxial stretching is performed after dyeing, it can be done before or during crosslinking treatment. Alternatively, uniaxial stretching can be performed at multiple stages.

[0067] In uniaxial stretching, stretching can be performed uniaxially between rollers with different circumferential speeds, or it can be performed uniaxially using heated rollers. Furthermore, uniaxial stretching can be dry stretching performed in the atmosphere, or wet stretching performed while the polyvinyl alcohol-based resin film is swollen using solvents or water. The stretching ratio is typically 3 to 8 times.

[0068] One method for dyeing polyvinyl alcohol (PVA) resin films with dichroic dyes is to immerse the film in an aqueous solution containing the dichroic dye. Iodine or a dichroic organic dye is used as the dichroic dye. It should be noted that the PVA resin film is preferably immersed in water before the dyeing process.

[0069] As a cross-linking treatment following dyeing with dichroic pigments, a common method is to immerse the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. When iodine is used as the dichroic pigment, the aqueous solution containing boric acid preferably contains potassium iodide.

[0070] The thickness of the polarizing film is typically 30 μm or less, preferably 15 μm or less, more preferably 13 μm or less, even more preferably 10 μm or less, and particularly preferably 8 μm or less. The thickness of the polarizing film is typically 2 μm or more, preferably 3 μm or more.

[0071] As a polarizing film, for example, as described in Japanese Patent Application Publication No. 2016-170368, a polarizing film obtained by aligning a dichroic pigment in a cured film obtained by polymerizing a liquid crystal compound can be used. As the dichroic pigment, a dichroic pigment having absorption in the wavelength range of 380 to 800 nm can be used, and organic dyes are preferred. Examples of dichroic pigments include azo compounds. The liquid crystal compound is a liquid crystal compound capable of polymerization while maintaining orientation, and may have polymerizable groups within its molecule. Alternatively, as described in WO2011 / 024891, a polarizing film can be formed from a dichroic pigment possessing liquid crystal properties.

[0072] The polarization degree of the visibility correction of the polarizing film is preferably 90% or more, more preferably 95% or more. There is no particular upper limit, but it is 99.9999% or less. Furthermore, the transmittance of the visibility correction monomer of the polarizing film is preferably 35% or more, more preferably 40% or more. There is no particular upper limit, but it is 49.9% or less. By giving the laminate this property of a polarizing film, reflected light is less likely to leak, making the color less noticeable.

[0073] (2) Protective film

[0074] The protective film laminated on one or both sides of the polarizing film can be a light-transmitting (preferably optically transparent) thermoplastic resin. Examples of protective films include polyolefin resins such as chain-like polyolefin resins (polypropylene resins, etc.), cyclic polyolefin resins such as norbornene resins, cellulose resins such as triacetyl cellulose and diacetyl cellulose, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate resins, (meth)acrylic resins such as methyl methacrylate resins, polystyrene resins, polyvinyl chloride resins, acrylonitrile-butadiene-styrene resins, acrylonitrile-styrene resins, polyvinyl acetate resins, polyvinylidene chloride resins, polyamide resins, polyacetal resins, modified polyphenylene ether resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyamide-imide resins, and polyimide resins.

[0075] The thickness of the protective film is usually 1 to 100 μm, but from the viewpoint of strength and operability, it is preferably 5 to 60 μm, more preferably 10 to 55 μm, and even more preferably 15 to 40 μm.

[0076] As described above, at least one of the protective films may have a surface treatment layer (coating layer) on its outer surface (the surface opposite to the polarizing film), such as a hard coating layer, an anti-glare layer, a light diffusion layer, an anti-reflection layer, a low refractive index layer, an antistatic layer, or an anti-fouling layer. It should be noted that the thickness of the protective film includes the thickness of the surface treatment layer.

[0077] The protective film can be attached to the polarizing film, for example, via an adhesive layer or a bonding agent layer. As the adhesive forming the adhesive layer, a water-based adhesive, an active energy radiation-cured adhesive, or a thermosetting adhesive can be used, preferably a water-based adhesive or an active energy radiation-cured adhesive. As the bonding agent layer, an bonding agent layer described later can be used.

[0078] Examples of aqueous adhesives include adhesives formed from aqueous solutions of polyvinyl alcohol (PVA) resins and aqueous two-component urethane emulsion adhesives. Among these, aqueous adhesives formed from aqueous solutions of PVA resins are particularly suitable. As for PVA resins, in addition to ethylene alcohol homopolymers obtained by saponifying polyvinyl acetate homopolymers, PVA copolymers obtained by saponifying copolymers of vinyl acetate and other monomers capable of copolymerization, or modified PVA polymers whose hydroxyl groups have been partially modified, can also be used. Aqueous adhesives may contain crosslinking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine compounds, hydroxymethyl compounds, isocyanate compounds, amine compounds, and polyvalent metal salts.

[0079] When using a water-based adhesive, after bonding the polarizing film to the protective film, it is preferable to perform a drying process to remove water contained in the water-based adhesive. After the drying process, a curing process can be performed, for example, at a temperature of 20–45°C.

[0080] The aforementioned active energy ray curable adhesive is an adhesive containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays, preferably an ultraviolet curable adhesive.

[0081] The aforementioned curable compounds can be cationicly polymerizable or free-radically polymerizable. Examples of cationicly polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule), oxetane compounds (compounds having one or more oxetane rings in the molecule), or combinations thereof. Examples of free-radically polymerizable curable compounds include (meth)acrylic acid compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), other vinyl compounds with free-radically polymerizable double bonds, or combinations thereof. Cationicly polymerizable and free-radically polymerizable curable compounds can also be used in combination. Active energy radiation-curable adhesives typically also contain cationic polymerization initiators and / or free-radical polymerization initiators for initiating the curing reaction of the aforementioned curable compounds.

[0082] When bonding the polarizing film and the protective film, surface activation treatment can be applied to at least one of their bonding surfaces to improve adhesion. Examples of surface activation treatments include dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, and ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.); and wet treatments using solvents such as water and acetone, such as ultrasonic treatment, saponification treatment, and anchor coating treatment. These surface activation treatments can be performed individually or in combination of two or more.

[0083] When bonding protective films to both sides of a polarizing film, the adhesives used to bond these protective films can be the same type of adhesive or different types of adhesives.

[0084] <Phase difference film>

[0085] The retardation film is composed of an A-plate and a C-plate. In addition, the retardation film may also include the substrate and alignment film described later, or it may include a retardation layer other than the A-plate and C-plate.

[0086] (1) Board A

[0087] The A-plate is preferably an A-plate having the characteristics shown in equations (1) to (3) below. The A-plate can be a positive A-plate or a λ / 4 plate. In addition, the A-plate preferably exhibits reverse wavelength dispersion. By having such an A-plate, the coloration of reflected light can be suppressed. The A-plate is arranged such that its slow axis is about 45° relative to the absorption axis of the polarizing film. The term about 45° means 45 ± 5°.

[0088] nx>ny≈nz...(1)

[0089] 0.80<R0A(450) / R0A(550)<0.93...(2)

[0090] 135nm<R0A(550)<150nm...(3)

[0091] In equations (1) to (3), nx represents the refractive index in the slow axis direction within the film surface, ny represents the refractive index in the direction orthogonal to the slow axis within the film surface, and nz represents the refractive index in the thickness direction of the film. R0A(λ) represents the in-plane phase difference value at wavelength λnm of plate A.

[0092] The condition ny≈nz includes not only the case where ny and nz are exactly equal, but also the case where ny and nz are substantially equal. Specifically, as long as the difference between ny and nz is within 0.01, it can be said that ny and nz are substantially equal.

[0093] R0A(λ) can be calculated based on the refractive index n(λ) at wavelength λnm and the thickness d using the following formula.

[0094] R0A(λ)=[nx(λ)-ny(λ)]×d

[0095] Here, R0A(450) / R0A(550) represents the wavelength dispersion of plate A, which is preferably 0.92 or less.

[0096] In addition, for the in-plane phase difference value R0A(λ) of plate A at wavelength λnm, R0A(450) is preferably 100nm or more and 135nm or less, R0A(550) is preferably 137nm or more and 145nm or less, and R0A(650) is preferably 137nm or more and 165nm or less.

[0097] (2) C board

[0098] For the C-plate, it is preferable that both the first C-plate and the second C-plate have the characteristics shown in equation (4) below. The C-plate can be a positive C-plate. By having this phase retardation film, the coloration of reflected light can be suppressed.

[0099] nx≈ny<nz...(4)

[0100] In equation (4), nx represents the refractive index in the slow axis direction within the film surface, ny represents the refractive index in the direction orthogonal to the slow axis within the film surface, and nz represents the refractive index in the thickness direction of the film.

[0101] The expression nx ≈ ny includes not only the case where nx and ny are completely equal, but also the case where nx and ny are substantially equal. Specifically, as long as the difference between nx and ny is within 0.01, it can be said that nx and ny are substantially equal.

[0102] Although it depends on the reflective properties of the light-reflecting layer described later, specifically, the phase difference value in the thickness direction of the C plate is preferably -100nm or more and 0nm or less at a wavelength of 550nm, more preferably -90nm or more and -20nm or less.

[0103] (3) Other phase difference layers

[0104] In addition to plates A and C, the phase retardation film may include one or more other layers with phase retardation (hereinafter sometimes referred to as "other phase retardation layers"). Examples of other phase retardation layers include touch sensors of display elements, sealing layers of light-emitting elements, and base films of light-emitting elements. Alternatively, other phase retardation layers may be protective films adhered to the polarizing film. The other phase retardation layers are disposed between the polarizing film and the light-reflecting layer, preferably between the light-reflecting layer and plate A or plate C, which is located closest to the light-reflecting layer.

[0105] Other retardation layers can also be A-plates, but are typically C-plates. Other retardation layers can have the properties shown in equation (9). That is, other retardation layers can be negative C-plates.

[0106] nx≈ny>nz...(9)

[0107] In equation (9), nx represents the refractive index in the slow axis direction within the film surface, ny represents the refractive index in the direction orthogonal to the slow axis within the film surface, and nz represents the refractive index in the thickness direction of the film.

[0108] The expression nx ≈ ny includes not only the case where nx and ny are completely equal, but also the case where nx and ny are substantially equal. Specifically, as long as the difference between nx and ny is within 0.01, it can be said that nx and ny are substantially equal.

[0109] (4) Relationship with light-reflecting layer

[0110] The phase difference film of at least plate A and plate C satisfies the following equation (5) or (6) based on the scattering half-value angle of the light reflection layer.

[0111] R th C1(550)<R th C2(550)...(5)

[0112] R th C2(550)<R th C1(550)...(6)

[0113] In equations (5) and (6), R th C(λ) represents the phase difference along the thickness direction at a wavelength of λnm on plate C. th C1 represents the phase difference value of the first C plate, Rth C2 represents the phase difference value of the 2C plate.

[0114] R th C(λ) can be calculated based on the refractive index n(λ) at wavelength λnm and the thickness d using the following formula.

[0115] R th C(λ)={〔nx(λ)+ny(λ)〕 / 2-nz}×d

[0116] R th C(450) / R th C(550) represents the wavelength dispersion of plate C, which is preferably 1.5 or less, and more preferably 1.1 or less.

[0117] The inventors conducted in-depth research and found that the optimal compensation value for a practical display device varies depending on the reflective properties of the light-reflecting layer. Equations (5) and (6) above are derived based on the above findings.

[0118] When the scattering half-value angle of the light-reflecting layer is 10° or greater, the first C plate and the second C plate preferably satisfy the relationship of equation (5). That is, the phase difference value R in the thickness direction of the first C plate is... th The phase difference R between plate C1 and plate 2C in the thickness direction th The magnitude of C2 affects the characteristics of reflected light, which were previously considered to have no impact. For the range of phase difference values, R0A (550) and R... th C1(550) and R th The sum of C2(550) is -50nm to +50nm, more preferably -20nm to +20nm, and even more preferably -10nm to +10nm. Furthermore, regarding the range of the phase difference value, R is preferred. th C1(550) and R th The sum of C2(550) is -100nm to +100nm, more preferably -80nm to +80nm, and even more preferably -60nm to +60nm. By making the phase retardation film satisfy the above relationship, the change in reflected light when viewed from an oblique direction can be suppressed.

[0119] In this invention, the scattering half-value angle of the light-reflecting layer is the following value: when light is incident on the light-reflecting layer from an elevation angle of 50°, in the variable angle scattering intensity analysis obtained by measuring every 1° within a 90° range centered on the positive reflection angle of 50°, it is the angle difference between two points where the scattering intensity reaches half of the maximum reflection intensity. Details are provided in the methods described in the embodiments below.

[0120] It should be noted that, as one implementation method, when the phase retardation film does not have a second C plate, R thCl(550) is preferably -100nm to 0nm, more preferably -80nm to -20nm.

[0121] On the other hand, when the scattering half-value angle of the light-reflecting layer is less than 10°, the first C plate and the second C plate preferably satisfy the relationship of equation (6). That is, the phase difference value R in the thickness direction of the first C plate is... th The phase difference R between plate C1 and plate 2C in the thickness direction th The magnitude of C2 affects the characteristics of reflected light that were previously considered unaffected. For the range of phase difference values, R is preferred. th A(550) and R th C1(550) and R th The sum of C2(550) is -50nm to +50nm, more preferably -20nm to +20nm, and even more preferably -10nm to +10nm. Furthermore, regarding the range of the phase difference value, R is preferred. th C1(550) and R th The sum of C2(550) is -100nm to +100nm, more preferably -80nm to +80nm, and even more preferably -60nm to +60nm. By making the phase retardation film satisfy the above relationship, the change in reflected light when viewed from an oblique direction can be suppressed.

[0122] (5) Methods for forming phase retardation films

[0123] The phase retardation film includes an A plate, a first C plate, and a second C plate, which can be formed from a thermoplastic resin or a composition containing a polymeric liquid crystal compound (described later). The A plate, the first C plate, and the second C plate are preferably formed from a composition containing a polymeric liquid crystal compound. Examples of layers formed from a composition containing a polymeric liquid crystal compound include layers obtained by curing the polymeric liquid crystal compound.

[0124] The relationships between Equations (1) to (3) satisfied by plate A, Equation (4) satisfied by plate 1C and plate 2C, and Equation (5) or Equation (6) satisfied by plate 1C and plate 2C can be controlled, for example, by adjusting the type and mixing ratio of the thermoplastic resin and polymeric liquid crystal compound used to form plate A and plate C, or by adjusting the thickness of plate A and plate C.

[0125] A layer obtained by curing a polymeric liquid crystal compound is formed, for example, on an alignment film disposed on a substrate. This substrate may be a strip-shaped substrate that functions to support the alignment film. This substrate acts as a release support, supporting the phase retardation film for transfer. Furthermore, a substrate with adhesive strength to the degree of peelability is preferred. Resin films, which are exemplified as materials for the aforementioned protective film, can be used as substrates.

[0126] The thickness of the substrate is not particularly limited, but it is preferably set to a range of 20 μm or more and 200 μm or less. If the thickness of the substrate is 20 μm or more, it can impart strength. On the other hand, if the thickness is 200 μm or less, when the substrate is cut into single sheets, the increase of processing chips and the wear of the cutting blade can be suppressed.

[0127] It should be noted that various anti-adhesion treatments can be applied to the substrate. Examples of anti-adhesion treatments include easy-bonding treatments, internal filler treatments, and embossing (knurling). By applying such anti-adhesion treatments to the substrate, adhesion between substrates during winding can be effectively prevented, enabling high-productivity manufacturing of optical films.

[0128] Layers obtained by curing a polymeric liquid crystal compound are sandwiched between alignment films on a substrate. That is, layers obtained by curing a polymeric liquid crystal compound are stacked on the alignment film in the order of substrate and alignment film.

[0129] It should be noted that the alignment film is not limited to a vertical alignment film; it can also be an alignment film in which the molecular axes of the polymeric liquid crystal compound are horizontally aligned, or an alignment film in which the molecular axes of the polymeric liquid crystal compound are tilted. When manufacturing plate A, a horizontal alignment film can be used; when manufacturing plate C, a vertical alignment film can be used. Preferably, the alignment film has solvent resistance that prevents dissolution due to coating of the composition containing the polymeric liquid crystal compound (described later), and heat resistance for solvent removal and heat treatment during the alignment of the liquid crystal compound. Examples of alignment films include alignment films containing an oriented polymer, photo-alignment films, and groove alignment films in which an uneven pattern or multiple grooves are formed on the surface and aligned thereto. The thickness of the alignment film is typically in the range of 10 nm to 10,000 nm, preferably in the range of 10 nm to 1,000 nm, more preferably 500 nm or less, and even more preferably in the range of 10 nm to 200 nm.

[0130] The resin used in the alignment film is not particularly limited as long as it is a resin known for use as a material in alignment films. Cured products obtained by curing monofunctional or polyfunctional (meth)acrylate monomers under a polymerization initiator, as previously known, can be used. Specifically, examples of (meth)acrylate monomers include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, and carbamate acrylates. It should be noted that the resin can be one of these or a mixture of two or more.

[0131] The photo-alignment film is formed from a composition comprising a polymer or monomer having a photoreactive group and a solvent. A photoreactive group is a group that generates liquid crystal alignment capability upon light irradiation. Specifically, it includes photoreactive groups that participate in orientation-inducing or isomerizing reactions, dimerization reactions, photocrosslinking reactions, or photodecomposition reactions of molecules caused by light irradiation, thus becoming the origin of liquid crystal alignment capability. Among these, groups participating in dimerization or photocrosslinking reactions exhibit excellent orientation properties, and are preferred from this perspective. As a photoreactive group, it is preferable to have a group having an unsaturated bond, particularly a double bond, and especially preferably a group having at least one selected from carbon-carbon double bonds (C=C), carbon-nitrogen double bonds (C=N), nitrogen-nitrogen double bonds (N=N), and carbon-oxygen double bonds (C=O).

[0132] Examples of photoreactive groups with C=C bonds include vinyl, polyene, stilbene, stilbenezyl, stilbenezyl-2-yl, chalcone, and cinnamoyl. Examples of photoreactive groups with C=N bonds include groups with aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups with N=N bonds include azophenyl, azonaphthyl, aromatic heterocyclic azo, diazo, and methyl... (formazan) group, and groups having an azobenzene structure, etc. Examples of photoreactive groups with C=O bonds include benzophenone group, coumarin group, anthraquinone group, and maleimide group. These groups can have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid group, and haloalkyl.

[0133] Among these, photoreactive groups that participate in the photodimerization reaction are preferred. Considering the need for less polarized light irradiation required for photoorientation and the ease of obtaining photoorientation films with excellent thermal stability and long-term stability, cinnamyl and chalcone groups are preferred. As a polymer having photoreactive groups, it is particularly preferred that the polymer side chain ends with a cinnamyl group that forms a cinnamic acid structure.

[0134] There is no particular limitation on the type of polymeric liquid crystal compound used in this embodiment; however, based on its shape, it can be classified into rod-shaped (rod-shaped liquid crystal compound) and disc-shaped (disc-shaped liquid crystal compound, disc-shaped liquid crystal compound). Furthermore, each has low-molecular-weight and high-molecular-weight types. It should be noted that "high-molecular-weight" generally refers to molecules with a degree of polymerization of 100 or higher (Polymer Physics: Phase Transition Dynamics, Masao Doi, p. 2, Iwanami Shoten, 1992).

[0135] In this embodiment, any polymerizable liquid crystal compound can be used. Alternatively, two or more rod-shaped liquid crystal compounds, two or more disc-shaped liquid crystal compounds, or a mixture of rod-shaped and disc-shaped liquid crystal compounds can be used.

[0136] It should be noted that, as a rod-shaped liquid crystal compound, the compound described in claim 1 of Japanese Patent Application Publication No. 11-513019, or in paragraphs

[0026] to

[0098] of Japanese Patent Application Publication No. 2005-289980, may be suitable, for example. As a disc-shaped liquid crystal compound, the compound described in paragraphs

[0020] to

[0067] of Japanese Patent Application Publication No. 2007-108732, or in paragraphs

[0013] to

[0108] of Japanese Patent Application Publication No. 2010-244038, may be suitable, for example.

[0137] Two or more polymerizable liquid crystal compounds may be used together. In this case, at least one of them has two or more polymerizable groups within its molecule. That is, the layer obtained by curing the polymerizable liquid crystal compound is preferably a layer formed by fixing the liquid crystal compound having polymerizable groups through polymerization. In this case, it is no longer necessary to exhibit liquid crystal properties after it has become a layer.

[0138] Polymerizable liquid crystal compounds have polymerizable groups capable of undergoing polymerization reactions. For example, polymerizable olefinic unsaturated groups, cyclic polymerizable groups, and other functional groups capable of addition polymerization reactions are preferred.

[0139] More specifically, examples of polymerizable groups include (meth)acryloyl, vinyl, styrene, and allyl. Among these, (meth)acryloyl is preferred. It should be noted that the term (meth)acryloyl is a concept encompassing both methacryloyl and acryloyl groups.

[0140] The layer obtained by curing the polymeric liquid crystal compound, as described below, can be formed, for example, by coating a composition containing the polymeric liquid crystal compound onto an alignment film. The composition may contain components other than the polymeric liquid crystal compound described above. For example, the composition preferably contains a polymerization initiator. The polymerization initiator used can be selected, for example, a thermal polymerization initiator or a photopolymerization initiator, depending on the form of the polymerization reaction. Examples of photopolymerization initiators include α-carbonyl compounds, azobin ethers, α-hydrocarbon-substituted aromatic azobin compounds, polynuclear quinone compounds, and combinations of triarylimidazolium dimers and p-aminophenyl ketones. The amount of polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, relative to the total solid content in the coating solution.

[0141] Furthermore, the composition may include a polymerizable monomer from the perspective of coating film uniformity and film strength. Examples of polymerizable monomers include free radical polymerizable or cationic polymerizable compounds. Among these, multifunctional free radical polymerizable monomers are preferred.

[0142] It should be noted that, as a polymerizable monomer, a monomer capable of copolymerizing with the aforementioned polymerizable liquid crystal compound is preferred. Specific examples of polymerizable monomers include those described in paragraphs

[0018] to

[0020] of Japanese Patent Application Publication No. 2002-296423. Regarding the amount of polymerizable monomer used, relative to the total mass of the polymerizable liquid crystal compound, it is preferably 1 to 50% by mass, more preferably 2 to 30% by mass.

[0143] Furthermore, the composition may include a surfactant to improve the uniformity and strength of the coated film. Conventionally known compounds can be cited as surfactants. Fluorinated compounds are particularly preferred. Specific surfactants include, for example, the compounds described in paragraphs

[0028] to

[0056] of Japanese Patent Application Publication No. 2001-330725 and the compounds described in paragraphs

[0069] to

[0126] of Japanese Patent Application Publication No. 2005-62673.

[0144] Additionally, the composition may contain a solvent, preferably an organic solvent. Examples of organic solvents include amides (e.g., N,N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Furthermore, two or more organic solvents may be used together.

[0145] In addition, the composition may contain various orientation agents such as vertical orientation promoters (e.g., polarizing film interface-side vertical orientation agents, air interface-side vertical orientation agents) and horizontal orientation promoters (e.g., polarizing film interface-side horizontal orientation agents, air interface-side horizontal orientation agents). Furthermore, in addition to the above-mentioned components, the composition may also contain adhesion modifiers, plasticizers, polymers, etc.

[0146] In this embodiment, the thicknesses of plate A, plate 1C, and plate 2C can be set to 0.1 μm or more and 5 μm or less. If the thicknesses of plate A, plate 1C, and plate 2C are within this range, sufficient durability can be obtained, which can help to achieve thinner laminates. Of course, the thicknesses of plate A, plate 1C, and plate 2C can be adjusted to obtain the desired in-plane phase difference value and the phase difference value in the thickness direction for layers with a phase difference of λ / 4, layers with a phase difference of λ / 2, positive plate A, or positive plate C, etc.

[0147] When the phase retardation film comprises two or more layers of polymeric liquid crystal compound cured as plates A, 1C, and 2C, layers of polymeric liquid crystal compound cured on the alignment film are respectively fabricated, and the two are laminated through an adhesive layer and a binder layer, thereby manufacturing the phase retardation film. After laminating the two, the substrate and the alignment film can be peeled off. The thickness of the phase retardation film is preferably 3 to 30 μm, more preferably 5 to 25 μm.

[0148] <Light Reflecting Layer>

[0149] The light-reflecting layer is a layer that reflects light incident on the laminate. Typically, it may contain the electrodes found in organic EL display elements. An organic EL display element has a thin-film structure with an organic light-emitting material layer sandwiched between a pair of facing electrodes. Electrons are injected into the organic light-emitting material layer from one electrode, and holes are injected from the other electrode, thereby causing electron-hole recombination within the organic light-emitting material layer to produce self-emission. Compared to backlighting liquid crystal display elements, it offers advantages such as better visibility, the ability to be further thinned, and the ability to achieve low-voltage DC drive.

[0150] There are no restrictions on the materials used to form the light-reflecting layer. The light-reflecting layer can be formed from metals such as gold, silver, copper, iron, nickel, chromium, molybdenum, titanium, and aluminum, or their alloys.

[0151] Visibility-corrected reflectance is the reflectance measured using the method described above. It is the reflectance corrected for visibility using the isochromatic function y(λ) (JIS Z8701). Visibility-corrected reflectance can be measured using a spectrophotometer.

[0152] As described above, when the scattering half-value angle of the light-reflecting layer is greater than 10° and the A plate, the 1C plate, and the 2C plate satisfy the relationship of equations (3) and (5), and when the scattering half-value angle of the light-reflecting layer is less than 10° and the A plate, the 1C plate, and the 2C plate satisfy the relationship of equations (3) and (6), the combination of this phase difference film and the light-reflecting layer can suppress the intensity change of reflected light when viewed from the tilt direction.

[0153] When the half-value angle of scattering of the light-reflecting layer is greater than 10°, the half-value angle can be greater than 10° and less than 30°. When the half-value angle of scattering of the light-reflecting layer is less than 10°, the half-value angle can be greater than 3° and less than 10°. The half-value angle of scattering of the light-reflecting layer can be adjusted by utilizing the material and surface shape of the light-reflecting layer.

[0154] <Adhesive layer>

[0155] The adhesive layer can be used to laminate the components of a laminate. When the light-reflecting layer includes electrodes for an organic EL display element, the organic EL display element and the retardation film can be laminated via the adhesive layer. The adhesive layer can be composed of an adhesive composition with resins such as (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether as the main component. Adhesive compositions with (meth)acrylic resins as the base polymer, exhibiting excellent transparency, weather resistance, and heat resistance, are particularly suitable. The adhesive composition can be of the active energy radiation curing type or the thermosetting type. The thickness of the adhesive layer is typically 3–30 μm, preferably 3–25 μm.

[0156] The (meth)acrylic resin (base polymer) used in the adhesive composition may, for example, be a polymer or copolymer with one or more (meth)acrylates such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, or 2-ethylhexyl (meth)acrylate as monomers. It is preferable to copolymerize the base polymer with polar monomers. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate, which have carboxyl, hydroxyl, amide, amino, or epoxy groups.

[0157] The adhesive composition may contain only the aforementioned base polymer, but typically also includes a crosslinking agent. Examples of crosslinking agents include: metal ions with a valence of divalent or higher that form a metal carboxylic acid salt between themselves and a carboxyl group; polyamine compounds that form an amide bond between themselves and a carboxyl group; polyepoxide compounds and polyols that form an ester bond between themselves and a carboxyl group; and polyisocyanate compounds that form an amide bond between themselves and a carboxyl group. Among these, polyisocyanate compounds are preferred.

[0158] Front Panel

[0159] A front panel can be disposed on the visible side of the polarizing plate. The front panel can be laminated to the polarizing plate via an adhesive layer. Examples of adhesive layers include the aforementioned adhesive layer and bonding agent layer.

[0160] Examples of suitable front panels include glass and front panels with a hard coating on at least one side of a resin film. For example, high-transmittance glass or tempered glass can be used. When using a particularly thin transparent material, chemically strengthened glass is preferred. The thickness of the glass can be, for example, from 100 μm to 5 mm.

[0161] A front panel formed by including a hard coating on at least one side of a resin film can be flexible, unlike conventional glass. The thickness of the hard coating is not particularly limited, and can be, for example, 5–100 μm.

[0162] As a resin membrane, it can be a membrane formed from polymers such as cycloolefin derivatives containing monomers such as norbornene or polycyclic norbornene monomers, cellulose (diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, isobutyl cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose), ethylene-vinyl acetate copolymers, polycyclic cyclic olefins, polyesters, polystyrene, polyamides, polyetherimides, polyacrylic acids, polyimides, polyamide-imides, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, epoxy resin, etc. The resin membrane can be unstretched, uniaxial, or biaxially stretched. These polymers can be used individually or in combination of two or more. Preferred resin films include polyamide-imide films or polyimide films with excellent transparency and heat resistance, uniaxial or biaxial stretched polyester films, cycloolefin derivative films with excellent transparency and heat resistance and capable of handling large-scale film production, polymethyl methacrylate films, and transparent triacetyl cellulose and isobutyl cellulose films without optical anisotropy. The thickness of the resin film can be 5–200 μm, preferably 20–100 μm.

[0163] <Light-blocking pattern>

[0164] A light-shielding pattern (border) can be formed on the display element side of the front panel. The light-shielding pattern can conceal the wiring of the display device from the user's view. The color and / or material of the light-shielding pattern are not particularly limited and can be formed from resin materials in various colors such as black, white, and gold. In one embodiment, the thickness of the light-shielding pattern can be 2μm to 50μm, preferably 4μm to 30μm, and more preferably 6μm to 15μm. Furthermore, to suppress air bubble intrusion and visibility of the interface caused by the height difference between the light-shielding pattern and the display area, the light-shielding pattern can be shaped.

[0165] <Manufacturing Method of Optical Laminates>

[0166] by Figure 1 Taking the laminate 100 shown as an example, the manufacturing method of the laminate will be described. The laminate 100 can be manufactured, for example, by laminating the polarizer 1 and the phase difference film 2 via adhesive layers 13 and 14.

[0167] The polarizing film 10 and the protective film 11 can be laminated separately using adhesive layers to manufacture the polarizing plate 1. The polarizing plate 1 can be manufactured by preparing long strip components, bonding the components together in a roll-to-roll manner, and then cutting them into a specified shape, or by bonding the components together after cutting them into a specified shape. Then, an adhesive layer 13 formed on the release film is laminated onto the polarizing film 10.

[0168] The phase retardation film 2 can be manufactured, for example, as shown below. An alignment film is formed on a substrate, and a coating liquid containing a polymerizable liquid crystal compound is coated onto the alignment film. While the polymerizable liquid crystal compound is aligned, it is irradiated with active energy rays to cure the polymerizable liquid crystal compound. By operating in this manner, a film having a first C plate 20 is manufactured. Similarly, a film having an A plate 21 and a second C plate 22 is manufactured.

[0169] An adhesive layer 15 is formed on the first C plate 20 or the A plate 21 to bond the film having the first C plate 20 to the film having the A plate 21. Then, the substrate film, or substrate film and alignment film of the A plate are peeled off, and an adhesive layer 16 is formed thereon to bond the film having the A plate 21 and the first C plate 20 to the film having the second C plate 22. Then, the substrate film, or substrate film and alignment film of the second C plate are peeled off to fabricate the phase retardation film 2.

[0170] The phase difference film 2 can be manufactured by preparing long strip components, bonding the components together in a roll-to-roll manner, and then cutting them into a specified shape, or by bonding the components after cutting them into a specified shape. The first C plate and the second C plate can be obtained by directly forming the first C plate and the second C plate on the A plate. That is, the adhesive layer 15 and the adhesive layer 16 can be omitted.

[0171] The release film on the adhesive layer 13 is peeled off, and the resulting polarizer is bonded to the phase retardation film 2 via the exposed adhesive layer 13. The film obtained in this manner can function as a circular polarizer and can be bonded to the light-reflecting layer 17 via the adhesive layer 14. When the light-reflecting layer 17 contains electrodes of an organic EL display element, the laminate 100 of this embodiment is manufactured by laminating the circular polarizer to the organic EL display element. The circular polarizer is, for example, laminated to the organic EL display element containing the light-reflecting layer 17 via the adhesive layer 14.

[0172] <Application>

[0173] The laminate of this embodiment can be used in a wide variety of display devices. A display device is a device having display elements, including a light-emitting element or light-emitting device as a light source. Examples of display devices include liquid crystal display devices, organic EL display devices, inorganic electroluminescent (hereinafter also called inorganic EL) display devices, electron emission display devices (e.g., field emission display devices (also called FED), surface field emission display devices (also called SED)), electronic paper (display devices using electronic ink, electrophoretic elements, plasma display devices, projection display devices (e.g., grating light valve (also called GLV) display devices, display devices with digital micromirror devices (also called DMD)) and piezoelectric ceramic displays, etc. Liquid crystal display devices include any of transmissive liquid crystal display devices, semi-transmissive liquid crystal display devices, etc. The laminate of this embodiment is particularly effective for organic EL display devices or inorganic EL display devices. In this case, Figure 1 The light-reflecting layer 17 shown is positioned as a component of the touch sensor and panel contained in the display device.

[0174] In particular, the organic EL display device with the invented stacked structure can suppress the intensity variation of reflected light from external sources, and can also display a stable black display capability when viewed from an oblique direction as it does when viewed from the front.

[0175] The above describes suitable embodiments of the present invention; however, the present invention is not limited to any of the above embodiments.

[0176] Example

[0177] The present invention will be described in more detail below with reference to embodiments and comparative examples. It should be noted that the present invention is not limited to the embodiments described below. It should also be noted that, unless otherwise specified, "%" and "parts" in the examples refer to mass percentage and mass parts, respectively.

[0178] <Determination Method>

[0179] (1) Methods for measuring membrane thickness:

[0180] The thickness of the film was measured using an ellipticity meter M-220 manufactured by Japan Spectrophotometer Co., Ltd., and contact film thickness gauges (MH-15M manufactured by Nikon Co., Ltd., TC101 counter, MS-5C).

[0181] (2) Method for measuring phase difference:

[0182] The phase difference in the thickness direction and the in-plane phase difference were measured using KOBRA-WPR from Oji Measurement Equipment Co., Ltd.

[0183] (3) Visibility-corrected reflectance when viewed from a 50° elevation angle:

[0184] The measurements were performed using the DMS803 display evaluation system manufactured by Instrument Systems GmbH.

[0185] <Preparation of the light-reflecting layer>

[0186] The following three light-reflecting layers are used. Each light-reflecting layer has a flat reflection spectrum, and white or silver reflected light can be observed.

[0187] Light reflective layer 1: NTK SUS 304B manufactured by Nippon Metal Industries, Ltd. as a SUS board.

[0188] Light-reflecting layer 2: The matte surface of Myfoil Thick Type 50 aluminum foil manufactured by UACJ Co., Ltd.

[0189] Light reflective layer 3: The MIRO55011GP, manufactured by Alanod Corporation, is used as a high-reflectivity reflector and is an aluminum vapor-deposited reflector.

[0190] The reflectivity of each light-reflecting layer is shown in Table 1. The reflectivity of each layer was measured using the DMS803 display evaluation system manufactured by Instrument Systems GmbH, with visibility correction applied.

[0191] The half-value angle of scattering of the light reflector is the angle difference between two points where the scattering intensity reaches half of the maximum reflection intensity, measured in 1° increments within a 90° range centered at a positive reflection angle of 50° when light is incident on the light reflector from an elevation angle of 50°. The variable-angle scattering intensity profiles of the light reflector shown in the following table all exhibit a unimodal distribution. For visual confirmation as described later, graphics were drawn on the surfaces of light reflectors 1–3 using a green oil-based marker (McKee, Zebra).

[0192] The measurement conditions for the light-reflecting layer are shown below.

[0193] Light source: Halogen lamp (Philips, Capsuleline LV (20W 310lm))

[0194] Convergence method: parabolic mirror

[0195] Converging spot diameter: 5mm

[0196] Distance between light source and light reflector: 100mm

[0197] [Table 1]

[0198] type Scattering half-value angle (°) Light reflector layer 1 20 Light reflector layer 2 15 Light reflector layer 3 7

[0199] <Making of a Circular Polarizing Plate>

[0200] [The fabrication of circular polarizing plate 1]

[0201] [Preparation of compositions for horizontally oriented film formation]

[0202] Five parts of a photo-aligning material with the following structure (weight average molecular weight: 30,000) were mixed with 95 parts of cyclopentanone (solvent). The resulting mixture was stirred at 80°C for 1 hour to obtain a composition for forming horizontally aligned films.

[0203]

[0204] [Preparation of compositions for vertically oriented film formation]

[0205] It uses SUNEVER SE610 manufactured by Nissan Chemical Industries, Ltd.

[0206] [Preparation of a composition for forming a horizontally oriented liquid crystal curable film]

[0207] To form a horizontally aligned liquid crystal cured film (plate A), polymerizable liquid crystal compound A and polymerizable liquid crystal compound B were used. Polymerizable liquid crystal compound A was manufactured using the method described in Japanese Patent Application Publication No. 2010-31223. Polymerizable liquid crystal compound B was manufactured using the method described in Japanese Patent Application Publication No. 2009-173893. Their respective molecular structures are given below.

[0208] [Polymerizable liquid crystal compound A]

[0209]

[0210] [Polymerizable liquid crystal compound B]

[0211]

[0212] Polymerizable liquid crystal compound A and polymerizable liquid crystal compound B were mixed at a mass ratio of 90:10. 1.0 part of a leveling agent (F-556; manufactured by DIC Corporation) and 6 parts of 2-dimethylamino-2-benzyl-1-(4-morpholinylphenyl)-1-butanone (Irgacure 369; manufactured by BASF JAPAN Corporation) as a polymerization initiator were added to 100 parts of the resulting mixture. Furthermore, N-methyl-2-pyrrolidone (NMP) was added to achieve a solids concentration of 13%, and the mixture was stirred at 80°C for 1 hour to obtain a composition for forming a horizontally oriented liquid crystal curable film.

[0213] [Preparation of a composition for forming a vertically oriented liquid crystal curable film]

[0214] To form vertically oriented liquid crystal curable films (plate 1C and plate 2C), a composition was prepared according to the following steps: 0.1 parts of F-556 as a leveling agent and 3 parts of Irgacure 369 as a polymerization initiator were added relative to 100 parts of Paliocolor LC242 (a registered trademark of BASF) as a polymerizable liquid crystal compound. Cyclopentanone was added to achieve a solids concentration of 13% to obtain a composition for forming vertically oriented liquid crystal curable films.

[0215] [Making of a polarizing plate]

[0216] A polyvinyl alcohol (PVA) film with an average degree of polymerization of approximately 2400, a saponification degree of ≥99.9 mol%, and a thickness of 75 μm was prepared. The PVA film was immersed in pure water at 30°C, and then immersed in an aqueous solution of iodine / potassium iodide / water at 30°C for iodine staining (iodine staining step). The iodine-stained PVA film was then immersed in an aqueous solution of potassium iodide / boric acid / water at 56.5°C for boric acid treatment (boric acid treatment step). The boric acid-treated PVA film was washed with pure water at 8°C and dried at 65°C to obtain a polarizing film with iodine adsorbed and oriented in the polyvinyl alcohol. The PVA film was stretched during the iodine staining and boric acid treatment steps. The total stretching ratio of the PVA film was 5.3 times. The thickness of the resulting polarizing film was 27 μm.

[0217] A polarizing film was bonded to a saponified triacetyl cellulose (TAC) film (Konica Minolta Co., Ltd., KC4UYTAC, 40 μm thick) using a holding roller with an aqueous adhesive. While maintaining the tension of the resulting laminate at 430 N / m, it was dried at 60°C for 2 minutes to obtain a polarizing plate with a TAC film on one side as a protective film. It should be noted that the aqueous adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (Kuraray Co., Ltd., "KurarayPoval KL318") and 1.5 parts of water-soluble polyamide epoxy resin (Taoka Chemical Industry Co., Ltd., "SumirezResin 650", 30% aqueous solution of solids) to 100 parts of water.

[0218] The optical properties of the obtained polarizing plate were measured. The polarizing film surface of the polarizing plate obtained above was used as the incident surface, and measurements were performed using a spectrophotometer (“V7100”, manufactured by Nippon Spectrophotometer Co., Ltd.). The absorption axis of the polarizing plate was aligned with the stretching direction of the polyvinyl alcohol. The obtained polarizing plate had a visibility-corrected monomer transmittance of 42.3%, a visibility-corrected polarization degree of 99.996%, a monomer hue a of -1.0, and a monomer hue b of 2.7.

[0219] [Fabrication of the phase retardation film (A plate)]

[0220] Corona treatment was performed on a cyclic olefin resin (COP) film (ZF-14-50) manufactured by Zeon Corporation, Japan. Corona treatment was performed using a TEC-4AX machine manufactured by USHIO Electric Corporation. One corona treatment was performed at an output power of 0.78 kW and a processing speed of 10 m / min. A horizontally oriented film-forming composition was coated onto the COP film using a bar coater and dried at 80°C for 1 minute. A polarized UV irradiation device (“SPOT CURE SP-9”, manufactured by USHIO Electric Corporation) was used to achieve a cumulative light intensity of 100 mJ / cm² at a wavelength of 313 nm. 2 The coated film was subjected to polarized UV exposure at an axial angle of 45°. The resulting horizontally oriented film had a thickness of 100 nm.

[0221] Next, a horizontally aligned liquid crystal curing film forming composition was applied to the horizontally aligned film using a bar coater and dried at 120°C for 1 minute. The coated film was then irradiated with ultraviolet light (cumulative light intensity at 365nm wavelength under a nitrogen atmosphere: 500mJ / cm²) using a high-pressure mercury lamp (“Unicure VB-15201BY-A”, manufactured by USHIO Electric Co., Ltd.). 2 This process forms a horizontally oriented liquid crystal cured film. The thickness of the horizontally oriented liquid crystal cured film is 2.3 μm.

[0222] An adhesive layer is laminated onto a horizontally aligned liquid crystal cured film. The film, consisting of the COP film, the alignment film, and the horizontally aligned liquid crystal cured film, is then bonded to glass via this adhesive layer. The COP film is then peeled off to obtain a sample for measuring the phase difference.

[0223] The phase difference R0A(λ) at each wavelength was measured, and the results are as follows:

[0224] R0A(450) = 121nm

[0225] R0A(550) = 142nm

[0226] R0A(650) = 146nm

[0227] R0A(450) / R0A(550)=0.85、

[0228] R0A(650) / R0A(550)=1.03,

[0229] The horizontally oriented liquid crystal curing film exhibits reverse wavelength dispersion.

[0230] The horizontally oriented liquid crystal curing film is a positive A-plate that satisfies the relationship nx>ny≈nz (hereafter sometimes simply referred to as "A-plate").

[0231] It should be noted that the phase difference R at each wavelength was measured. th A(λ), the result is:

[0232] R th A(450) = 61nm

[0233] R th A(550) = 71nm

[0234] R th A(650)=73nm.

[0235] [Fabrication of vertically aligned liquid crystal curing film (C-plate)]

[0236] The COP film was subjected to corona treatment. The corona treatment conditions were the same as described above. A vertically oriented film-forming composition was coated onto the COP film using a bar coater, and dried at 80°C for 1 minute to obtain a vertically oriented film. The thickness of the resulting vertically oriented film was 50 nm.

[0237] The vertically aligned liquid crystal curable film forming composition was applied to the vertically aligned film using a bar coater and dried at 90°C for 120 seconds. The coated film was then irradiated with ultraviolet light (cumulative light intensity at 365nm wavelength under nitrogen atmosphere: 500mJ / cm²) using a high-pressure mercury lamp (“Unicure VB-15201BY-A”, manufactured by USHIO Electric Co., Ltd.). 2 This process forms a vertically oriented liquid crystal cured film. By operating as described above, a film is obtained consisting of a COP film, a vertically oriented film, and a vertically oriented liquid crystal cured film. The thickness of the vertically oriented liquid crystal cured film is 0.7 μm.

[0238] An adhesive layer is laminated onto a vertically aligned liquid crystal cured film. The film formed by the COP film, alignment film, and vertically aligned liquid crystal cured film is then bonded to glass via this adhesive layer. The COP film is peeled off to obtain a sample for measuring the phase difference. The phase difference value R at a wavelength of 550 nm is measured. th C1(550), the result is:

[0239] R th C1(550) = -50nm.

[0240] The vertically oriented liquid crystal curing film is a positive C-plate (the first C-plate) that satisfies the relationship nx≈ny<nz.

[0241] Except for adjusting the thickness of the vertically aligned liquid crystal cured film to 0.4 μm, the vertically aligned film and the vertically aligned liquid crystal cured film were formed following the same steps as described above, and an adhesive layer was laminated on the vertically aligned liquid crystal cured film. The film formed by the COP film, the alignment film, and the vertically aligned liquid crystal cured film was then bonded to the glass via this adhesive layer. The COP film was peeled off to obtain a sample for measuring the phase difference. The phase difference value R at a wavelength of 550 nm was measured. th C2(550), the result is that R th C2(550) = -30nm. The vertically oriented liquid crystal curing film is a positive C-plate (the second C-plate) that satisfies the relationship nx≈ny<nz.

[0242] The vertically oriented liquid crystal cured film and the vertically oriented liquid crystal cured film (first C plate) formed on the COP film are bonded to the horizontally oriented liquid crystal cured film and the horizontally oriented liquid crystal cured film (A plate) formed on the COP film using an adhesive. Then, the COP film on the A plate side is peeled off, resulting in a film sequentially stacked with the COP film, the first C plate, and the A plate. Next, the A plate side of this film is bonded to the vertically oriented liquid crystal cured film and the vertically oriented liquid crystal cured film (second C plate) formed on the COP film using an adhesive. Then, the COP film on the second C plate side is peeled off, resulting in a film sequentially stacked with the COP film, the first C plate, the A plate, and the second C plate.

[0243] The COP film stacked on the first C plate is peeled off, and the vertically oriented liquid crystal curing film (first C plate) is subjected to corona treatment. The corona treatment conditions are set as described above. The polarizing film of the polarizing plate and the vertically oriented liquid crystal curing film (first C plate) are laminated together via an adhesive layer in such a way that the polarizing film of the polarizing plate and the vertically oriented liquid crystal curing film (first C plate) are in contact with each other. At this time, the angle between the absorption axis of the polarizing film and the slow axis of the horizontally oriented liquid crystal curing film is 45°. By operating in this manner, a circular polarizing plate 1 is obtained by laminating the phase difference film and the polarizing plate via an adhesive layer. The circular polarizing plate 1 has a layer structure consisting of a TAC film, a polarizing film, an adhesive layer, a vertically oriented liquid crystal curing film (first C plate), an adhesive layer, a horizontally oriented liquid crystal curing film (A plate), an adhesive layer, and a vertically oriented liquid crystal curing film (second C plate). th A(550)+R th C1(550)+R th C2(550)=9nm.

[0244] [The Making of Circular Polarizing Plate 2]

[0245] In addition to making the thickness of the vertically oriented liquid crystal curing film 1.1 μm, R th C1(550) = -80nm, and without setting a second C plate, a circular polarizing plate 2 is made in the same way as the circular polarizing plate 1.

[0246] [The Making of Circular Polarizing Plate 3]

[0247] Besides making R th C1(550) = -30nm, R th Beyond C2(550)=-50nm, a circular polarizing plate 3 is fabricated in the same manner as the circular polarizing plate 1.

[0248] [The fabrication of circular polarizing plate 4]

[0249] Except for not setting up the 1C board and making R th Beyond C2(550)=-80nm, a circular polarizing plate 4 is fabricated in the same manner as the circular polarizing plate 1.

[0250] <Example 1>

[0251] An adhesive layer is stacked on the surface exposed by peeling off the COP film from the circular polarizer. The circular polarizer 1 and the light-reflecting layer 1 are then stacked via this adhesive layer to obtain a laminate.

[0252] The rate of change of visibility-corrected reflectance was measured for the resulting laminate. Specifically, the visibility-corrected reflectance was measured using a display evaluation system DMS803 by changing the in-plane angle of the laminate from an elevation angle of 50°. The reflectance hue value at the in-plane angle where the measured visibility-corrected reflectance value reaches its maximum, and the rate of change of the visibility-corrected reflectance value when the in-plane angle is increased by 90°, were calculated.

[0253] The visibility of the pattern drawn on the surface of the light-reflecting layer was visually evaluated on the resulting laminate. The pattern was a green Landolt ring with a diameter of 3 mm and an opening of 0.5 mm. The opening direction was random. Observation was performed by varying the relationship between the optical axis of the horizontally aligned liquid crystal curing film and the observer's position. Specifically, it was observed visually from an elevation angle of approximately 50° at an in-plane angle parallel to the fast axis of plate A. The hue of the reflected light in this direction was green, and since it was similar to the color of the pattern drawn on the surface of the light-reflecting layer, observation became relatively difficult. On the other hand, when observed visually from an elevation angle of approximately 50° at an in-plane angle parallel to the slow axis of plate A, the hue of the reflected light was red, and since it was different from the color of the pattern drawn on the surface of the light-reflecting layer, observation became relatively easy. The visibility of the opening direction of the pattern was clearly determined in both the slow axis and fast axis directions using criteria 1 to 4 described below, according to the following evaluation criteria.

[0254] "1": The opening direction can be clearly identified.

[0255] “2”: Able to identify the direction of the opening.

[0256] “3”: Able to identify the direction of the opening when staring.

[0257] “4”: Unable to identify the opening direction.

[0258] The results show that the laminate obtained in Example 1 exhibits uniform color of reflected light when viewed from any direction, and can form a good black display at a wide viewing angle. These results are presented in Table 2.

[0259] [Examples 2-6, Comparative Examples 1-6]

[0260] Except for changing the combination of the circular polarizer and the light-reflecting layer as shown in Table 2, a laminate was fabricated in the same manner as in Example 1. The skew angle difference of the resulting laminate was measured in the same manner as in Example 1. Furthermore, the hue of the reflected light was visually observed on the resulting laminate as in Example 1, with the relationship between the optical axis of the horizontally aligned liquid crystal curing film and the observer's position changed. The results are shown in Table 2.

[0261] [Table 2]

[0262]

[0263] Industrial availability

[0264] The optical laminate of the present invention can be applied, for example, to organic EL display devices.

[0265] Explanation of reference numerals in the attached figures

[0266] 1. Polarizing plate, 2. Phase retardation film, 10. Polarizing film, 11. Protective film, 13 and 14. Adhesive layers, 15 and 16. Bonding layers, 17. Light reflection layer, 20. Plate 1C, 21. Plate A, 22. Plate 2C, 30. Elevation angle, 32. In-plane angle, 40, 41, and 42. Direction, 100. Optical laminate.

Claims

1. An optical laminate comprising a polarizing film, an A plate, a first C plate, and a second C plate, wherein the polarizing film, the first C plate, the A plate, and the second C plate are sequentially provided. The angle between the absorption axis of the polarizing film and the slow axis of plate A is 45°±5°. The rate of change in visibility-corrected reflectivity when the optical laminate is attached to the light-reflecting layer is less than 15%. The scattering half-value angle of the light-reflecting layer is less than 10°. The optical laminate satisfies the following equations (iii), (vi) and (vii): 135nm<ROA(550)<150nm…(iii) -100nm≤R th C2(550)<R th C1(550)≤0nm…(vi) -100nm≤R th C1(550)+R th C2(550)…(vii) In the above formula, R0A(550) represents the in-plane phase difference value of plate A at a wavelength of 550nm, R th C1(550) represents the phase difference value along the thickness direction of the first C plate at a wavelength of 550 nm, R th C2(550) represents the phase difference in the thickness direction of the second C plate at a wavelength of 550 nm.

2. The optical laminate according to claim 1, which satisfies the following formula (viii): 0.80<R0A(450) / R0A(550)<0.93...(viii) In the above formula, R0A(450) represents the in-plane phase difference value of plate A at a wavelength of 450nm, and R0A(550) represents the in-plane phase difference value of plate A at a wavelength of 550nm.

3. The optical laminate according to claim 1 or 2, further comprising a front panel, a light-shielding pattern, or a touch sensor.

4. The optical laminate according to any one of claims 1 to 3, wherein, A front panel is disposed on the visible side of the polarizing film.

5. The optical laminate according to claim 4, wherein, A touch sensor is disposed between the polarizing film and the front panel.

6. An organic EL display device, comprising: Light reflector layer, and The optical laminate according to any one of claims 1 to 5.

7. An organic EL display device, comprising: A light-reflecting layer with a scattering half-value angle of less than 10°, and the optical laminate as described in claim 1.

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