Phase difference film, laminated optical film, optical article, and virtual reality display device

Abstract

The present invention addresses the problem of providing a phase difference film, a laminated optical film, an optical article, and a virtual reality display device with which there is little ghosting when used in a virtual reality display device, an electronic viewfinder, or the like. This phase difference film is obtained by arranging a light interference layer and a phase difference layer adjacent to each other in this order, and the film thickness of the light interference layer satisfies 60 nm to 110 nm or 230 nm to 330 nm.

Description

Technical Field

[0001] The present invention relates to a retardation film, a laminated optical film, an optical article, and a virtual reality display device. Background Art

[0002] A reflective polarizer is a polarizer having a function of reflecting one polarized light of incident light and transmitting the other polarized light. The reflected light and the transmitted light based on the reflective polarizer become mutually orthogonal polarization states. Here, the mutually orthogonal polarization states refer to polarization states that are diametrically opposite to each other on the Poincare sphere. For example, mutually orthogonal linearly polarized lights, and right-handed circularly polarized light and left-handed circularly polarized light belong to this category.

[0003] Regarding a linear reflective polarizer in which the transmitted light and the reflected light are linearly polarized light, for example, a film formed by stretching a dielectric multilayer film as described in Patent Document 1 and a wire grid polarizer as described in Patent Document 2 are known.

[0004] Moreover, as a reflective circular polarizer in which the transmitted light and the reflected light are circularly polarized light, for example, a film having a light reflection layer in which a cholesteric liquid crystal phase is immobilized as described in Patent Document 3 is known.

[0005] The reflective polarizer is used for the purpose of extracting only a specific polarized light from incident light, or separating incident light into two polarized lights. For example, in a liquid crystal display device, it can be used as a brightness enhancement film for improving light use efficiency by reflecting unnecessary polarized light from a backlight and reusing it. Also, in a liquid crystal projector, it can also be used as a beam splitter that separates light from a light source into two linearly polarized lights and supplies them to a liquid crystal panel respectively.

[0006] Moreover, in recent years, a method of using a reflective polarizer for the purpose of reflecting a part of light from external light and / or an image display device to generate a virtual image or a real image has been proposed. For example, a vehicle-mounted rearview mirror (Room Mirror) that uses a reflective polarizer to reflect light from behind is disclosed in Patent Document 4. Also, a method is disclosed in Patent Document 5: A linear reflective polarizer and a half mirror (half-transmissive mirror) are arranged in a condenser lens system in a virtual reality display device (head-mounted display), and a retardation film having a function of a quarter-wave plate is further arranged between them, thereby miniaturizing and thinning the display unit.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-053705

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2015-028656

[0011] Patent Document 3: Japanese Patent No. 6277088

[0012] Patent Document 4: Japanese Patent Application Laid-Open No. 2017-227720

[0013] Patent Document 5: Japanese Patent Application Laid-Open No. 2003-504663 Summary of the Invention

[0014] Technical Problem to be Solved by the Invention

[0015] According to the research of the present inventors, in the virtual reality display device described in Document 5, double images are observed, and there is room for further improvement.

[0016] The present invention has been completed in view of the above problems, and the problem to be solved by the present invention is to provide a retardation film, a laminated optical film, an optical article, and a virtual reality display device that produce less double images when used in a virtual reality display device, an electronic viewfinder, etc.

[0017] Means for Solving the Technical Problem

[0018] The present inventors conducted in-depth research on the above problems and found that the above problems can be achieved by the following structure.

[0019] 〔1〕A retardation film formed by sequentially arranging an optical interference layer and a retardation layer adjacent to each other, wherein the film thickness of the optical interference layer is 60 nm to 110 nm or 230 nm to 330 nm.

[0020] 〔2〕The retardation film according to 〔1〕, wherein

[0021] the refractive index in the in-plane direction of the optical interference layer is 1.50 to 1.70.

[0022] 〔3〕The retardation film according to 〔1〕, wherein

[0023] the refractive index in the in-plane direction of the optical interference layer is 1.53 to 1.59.

[0024] 〔4〕The retardation film according to any one of 〔1〕 to 〔3〕, wherein

[0025] the retardation film further has an adhesive layer, and the retardation film is formed by sequentially arranging the adhesive layer, the optical interference layer, and the retardation layer adjacent to each other, wherein

[0026] when the refractive index of the adhesive layer is nA and the average refractive index of the retardation layer is nL, the refractive index nI in the in-plane direction of the optical interference layer is (nA × nL)1 / 2 -0.03 ≤ nI ≤ (nA × nL) 1 / 2 +0.03

[0027] 〔5〕The retardation film according to any one of 〔1〕 to 〔4〕, wherein

[0028] the above-mentioned light interference layer is a photo-aligned film

[0029] 〔6〕The retardation film according to any one of 〔1〕 to 〔4〕, wherein

[0030] the above-mentioned light interference layer is a C-plate

[0031] 〔7〕The retardation film according to 〔6〕, wherein

[0032] a compound having a cinnamoyl group is present between the above-mentioned C-plate and the above-mentioned retardation layer

[0033] 〔8〕The retardation film according to any one of 〔1〕 to 〔4〕, wherein

[0034] the above-mentioned light interference layer is a hard coat

[0035] 〔9〕A laminated optical film having at least a retardation film and a linear reflection polarizer, wherein

[0036] the above-mentioned retardation film is the retardation film according to any one of 〔1〕 to 〔8〕, and the above-mentioned linear reflection polarizer is disposed on the side of the above-mentioned retardation layer opposite to the above-mentioned light interference layer

[0037] 〔10〕The laminated optical film according to 〔9〕, wherein

[0038] the laminated optical film further includes a linear polarizer

[0039] 〔11〕The laminated optical film according to 〔10〕, wherein

[0040] the above-mentioned linear polarizer at least includes a light absorption anisotropic layer containing a liquid crystal compound and a dichroic substance

[0041] 〔12〕The laminated optical film according to 〔9〕, wherein

[0042] the laminated optical film further includes a positive C-plate

[0043] 〔13〕The laminated optical film according to 〔9〕, wherein

[0044] the laminated optical film further includes an antireflection layer

[0045] 〔14〕The laminated optical film according to 〔13〕, wherein

[0046] The above antireflection layer is a moth-eye film or an AR film.

[0047] 〔15〕The laminated optical film according to 〔9〕, wherein

[0048] the laminated optical film contains a resin substrate having a peak temperature of the loss tangent tanδ of 170°C or lower.

[0049] 〔16〕An optical article comprising the laminated optical film according to any one of 〔9〕 to 〔15〕 and a lens.

[0050] 〔17〕A virtual reality display device comprising the optical article according to 〔16〕.

[0051] Advantages of the Invention

[0052] According to the present invention, it is possible to provide a retardation film, a laminated optical film, an optical article, and a virtual reality display device that generate less ghosting when used in a virtual reality display device, an electronic viewfinder, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a schematic diagram showing an example of the retardation film of the present invention.

[0054] Figure 2 is a schematic diagram showing another example of the retardation film of the present invention.

[0055] Figure 3 is an example of a virtual reality display device using the laminated optical film of the present invention.

[0056] Figure 4 is an example of a virtual reality display device using the laminated optical film of the present invention.

[0057] Figure 5 is a schematic diagram showing an example of the laminated optical film of the present invention.

[0058] Figure 6 is a diagram for explaining the operation of a conventional retardation film.

[0059] Figure 7 is a diagram for explaining the operation of the retardation film of the present invention.

[0060] Figure 8 is another example of a virtual reality display device using the retardation film of the present invention. DETAILED DESCRIPTION

[0061] Hereinafter, the present invention will be described in detail. The description of the constituent elements described below is sometimes completed based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0062] In addition, in this specification, the numerical range represented by "~" means the range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0063] In this specification, regarding "orthogonal", it does not mean exactly 90° in the strict sense, but means 90° ± 10°, preferably 90° ± 5°. And regarding "parallel", it does not mean exactly 0° in the strict sense, but means 0° ± 10°, preferably 0° ± 5°. Furthermore, regarding "45°", it does not mean exactly 45° in the strict sense, but means 45° ± 10°, preferably 45° ± 5°.

[0064] In this specification, the "absorption axis" means the polarization direction in which the in-plane absorbance becomes maximum when linearly polarized light is incident. And the "reflection axis" means the polarization direction in which the in-plane reflectance becomes maximum when linearly polarized light is incident. And the "transmission axis" means the direction orthogonal to the absorption axis or the reflection axis in the plane. Furthermore, the "slow axis" means the direction in which the refractive index in the plane becomes maximum.

[0065] In this specification, unless otherwise specified, the phase difference means the in-plane retardation, denoted as Re(λ). Here, Re(λ) represents the in-plane retardation at wavelength λ, and if not otherwise specified, the wavelength λ is set to 550 nm.

[0066] [[ID=1`2]]And in this specification, the retardation in the thickness direction at wavelength λ is denoted as Rth(λ), and if not otherwise specified, the wavelength λ is set to 550 nm.

[0067] Regarding Re(λ) and Rth(λ), the values measured at wavelength λ using AxoScan OPMF-1 (manufactured by Opto Science, Inc.) can be used. By inputting the average refractive index ((nx + ny + nz) / 3) and the film thickness (d (μm)) using AxoScan, the following can be calculated:

[0068] Slow axis direction (°)

[0069] Re(λ) = R0(λ)

[0070] Rth(λ) = ((nx + ny) / 2 - nz) × d.

[0071] [Phase difference film]

[0072] The phase difference film of the present invention is formed by sequentially and adjacently arranging an optical interference layer and a phase difference layer, and the film thickness of the above optical interference layer is 60 nm to 110 nm or 230 nm to 330 nm.

[0073] Hereinafter, the phase difference film of the present invention will be described in detail with reference to the drawings.

[0074] Figure 1 is a schematic cross-sectional view showing an example of the structure of the retardation film 10. In Figure 1 the shown manner, the retardation film 10 is composed of a retardation layer 21 and an optical interference layer 22, and is disposed adjacent to each other.

[0075] The retardation film of the present invention can be used for a laminated optical film. The laminated optical film can be used for an optical article, and the optical article is used for a virtual reality display device. The retardation film has the above structure, and by setting the film thickness of the above optical interference layer to satisfy the above relationship, an antireflection effect can be imparted. Thus, in the conventional structure without an optical interference layer, the reflected light generated by the interface reflection between the retardation layer and the layer adjacent to the retardation layer (for example, an adhesive layer and a lens, etc.) can be suppressed. Here, when circularly polarized light is reflected by the interface, the rotation direction of the circularly polarized light changes (for example, right-handed circularly polarized light becomes left-handed circularly polarized light due to interface reflection). Since the rotation direction of the circularly polarized light reflected by the interface changes, it becomes one of the causes of ghosting. Therefore, it is considered that by suppressing the interface reflection, the generation of ghosting can be suppressed.

[0076] The retardation film of the present invention may include an adhesive layer for attaching the retardation film to a lens. Figure 2 is a schematic cross-sectional view showing an example of the structure of the retardation film 11. In Figure 2 the shown manner, the retardation film 11 is composed of a retardation layer 21, an optical interference layer 22, and an adhesive layer 23, and is disposed adjacent to each other.

[0077] Hereinafter, the action of the retardation film of the present invention will be described in more detail.

[0078] First, Figure 6 a description will be given of a conventional structure without an optical interference layer.

[0079] Figure 6 The shown example is one in which a retardation film 90 having a retardation layer 21 and an adhesive layer 23 is laminated on a lens 600 on the adhesive layer 23 side, and a linear reflection polarizer 102 is laminated on the retardation layer 21 side with an adhesive layer 101 interposed therebetween. This structure corresponds to an optical article for a virtual reality display device described later, and is used as a reciprocating optical system (retroreflective optical system) in combination with a half mirror. When used as a reciprocating optical system, Figure 6 the upper side (lens 600 side) is the image display device side, and the lower side (linear reflection polarizer 102 side) is the visual recognition side.

[0080] For example, if right-handed circularly polarized light is incident from the lens 600 side, the right-handed circularly polarized light that passes through the lens 600 and the adhesive layer 23 is converted into linearly polarized light in the retardation layer 21. As an example, it is described as an example of linearly polarized light in the left-right direction in the figure. This linearly polarized light passes through the adhesive layer 101 and is incident on the linear reflection polarizer 102. For example, when the linear reflection polarizer 102 reflects linearly polarized light in the left-right direction in the figure and transmits linearly polarized light in the direction perpendicular to the plane of the figure in the drawing, the linearly polarized light in the left-right direction incident on the linear reflection polarizer 102 is reflected. The reflected linearly polarized light in the left-right direction passes through the adhesive layer 101 and is incident on the retardation layer 21. The retardation layer 21 converts the linearly polarized light in the left-right direction into right-handed circularly polarized light and transmits it. This right-handed circularly polarized light passes through the adhesive layer 23 and the lens 600. The transmitted light is incident on, for example, a half mirror.

[0081] Here, a part of the right-handed circularly polarized light reflected by the linear reflection polarizer 102 and converted by the retardation layer 21 is reflected at the interface between the retardation layer 21 and the adhesive layer 23. And even in a structure without the adhesive layer 23, this circularly polarized light is reflected at the interface between the retardation layer 21 and other layers. The rotation direction of the right-handed circularly polarized light reflected at the interface changes to the opposite direction. That is, the right-handed circularly polarized light reflected at the interface becomes left-handed circularly polarized light. The retardation layer 21 converts this left-handed circularly polarized light into linearly polarized light in the direction perpendicular to the plane of the figure in the drawing. This linearly polarized light passes through the adhesive layer 101 and is incident on the linear reflection polarizer 102. However, since the linear reflection polarizer 102 has a transmission axis in the direction perpendicular to the plane of the paper, the linearly polarized light in the direction perpendicular to the plane of the paper passes through the linear reflection polarizer 102 and is emitted to the visual recognition side. In this way, in the conventional structure, unnecessary light reflected at the interface is emitted to the visual recognition side, so it is visually recognized as a ghost image.

[0082] Next, use Figure 7 The structure using a retardation film having an optical interference layer according to the present invention will be described.

[0083] Figure 7 The example shown is an example in which a retardation film 11 having a retardation layer 21, an optical interference layer 22, and an adhesive layer 23 is laminated on the lens 600 on the adhesive layer 23 side, and a linear reflection polarizer 102 is laminated on the retardation layer 21 side with the adhesive layer 101 interposed therebetween. This structure corresponds to an optical article for a virtual reality display device to be described later, and is used as a reciprocating optical system (folded optical system) in combination with a half mirror. When used as a reciprocating optical system, Figure 7 the upper side (the lens 600 side) is the image display device side, and the lower side (the linear reflection polarizer 102 side) is the visual recognition side.

[0084] For example, if right-handed circularly polarized light is incident from the lens 600 side, the right-handed circularly polarized light that passes through the lens 600, the adhesive layer 23, and the optical interference layer 22 is converted into linearly polarized light in the retardation layer 21. As an example, it is described as an example of linearly polarized light in the left-right direction in the figure. This linearly polarized light passes through the adhesive layer 101 and is incident on the linear reflection polarizer 102. For example, when the linear reflection polarizer 102 reflects linearly polarized light in the left-right direction in the figure and transmits linearly polarized light in the direction perpendicular to the plane of the figure in the figure, the linearly polarized light in the left-right direction incident on the linear reflection polarizer 102 is reflected. The reflected linearly polarized light in the left-right direction passes through the adhesive layer 101 and is incident on the retardation layer 21. The retardation layer 21 converts the linearly polarized light in the left-right direction into right-handed circularly polarized light and transmits it. This right-handed circularly polarized light passes through the optical interference layer 22, the adhesive layer 23, and the lens 600. The transmitted light is incident on, for example, a half mirror.

[0085] Moreover, a part of the right-handed circularly polarized light reflected by the linear reflection polarizer 102 and converted by the retardation layer 21 is reflected at the interface between the retardation layer 21 and the optical interference layer 22 (in the figure, reflected light I1). Also, another part of the right-handed circularly polarized light is reflected at the interface between the optical interference layer 22 and the adhesive layer 23 (in the figure, reflected light I2). The rotation directions of the right-handed circularly polarized light reflected at each interface, that is, the reflected lights I1 and I2, change in opposite directions. That is, the right-handed circularly polarized light reflected at the interface, that is, the reflected lights I1 and I2, respectively become left-handed circularly polarized light. The left-handed circularly polarized light, that is, the reflected lights I1 and I2, is converted into linearly polarized light in the direction perpendicular to the plane of the figure by the retardation layer 21. This linearly polarized light passes through the adhesive layer 101 and is incident on the linear reflection polarizer 102. However, since the linear reflection polarizer 102 has a transmission axis in the direction perpendicular to the paper surface, the linearly polarized light in the direction perpendicular to the paper surface passes through the linear reflection polarizer 102 and is emitted to the visual recognition side.

[0086] Here, since the optical path lengths of the reflected light I1 reflected at the interface between the retardation layer 21 and the optical interference layer 22 and the reflected light I2 reflected at the interface between the optical interference layer 22 and the adhesive layer 23 are different, interference occurs. Depending on the difference in the optical path lengths of the reflected light I1 and the reflected light I2 (that is, the phase shift amount), they sometimes enhance each other and sometimes weaken each other. However, in the present invention, by setting the film thickness of the optical interference layer 22 to 60 nm to 110 nm or 230 nm to 330 nm, the mutual weakening of the reflected light I1 and the reflected light I2 is generated, and unnecessary light reflected at the interface can be suppressed from being emitted to the visual recognition side, thereby reducing ghosting.

[0087] In addition, the film thickness of the above-described optical interference layer 22 is defined such that in the vicinity of the front surface and near a wavelength of 550 nm, mutual attenuation occurs between the reflected light I1 and the reflected light I2, that is, the phases of the reflected light I1 and the reflected light I2 are substantially shifted by λ / 2 or substantially shifted by 3λ / 2. The aspects are as follows: Regarding interface reflection, in the process of incident light from the front surface and the inclined direction with respect to the interface, particularly in the vicinity of the front surface is an important aspect, and light near a wavelength of 550 nm contributes greatly to the visual recognition of double images. Aspects such as the refractive index of the optical interference layer 22.

[0088] 〔Phase difference layer〕

[0089] The phase difference layer used in the present invention is a retardation plate having a function of converting linearly polarized light of a certain specific wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light). More specifically, it is a plate in which the in-plane retardation Re at a specified wavelength of λ nm exhibits λ / 4 (or an odd multiple thereof).

[0090] The in-plane retardation (Re(550)) of the phase difference layer at a wavelength of 550 nm can have an error of about 25 nm with respect to the ideal value (137.5 nm). For example, it is preferably 110 to 160 nm, more preferably 120 to 150 nm.

[0091] The phase difference layer used in the present invention is more preferably a layer that exhibits the characteristics of a λ / 4 plate at each wavelength throughout the visible light region. Such a phase difference layer is particularly called a broadband λ / 4 plate. The broadband λ / 4 plate preferably satisfies the following formulas (A) and (B) for the in-plane retardation (Re(λ)) at a wavelength of λ nm.

[0092] Formula (A) Re(450) / Re(550) < 1.00

[0093] Formula (B) Re(650) / Re(550) ≥ 1.00

[0094] Re(450) represents the in-plane retardation of the λ / 4 plate at a wavelength of 450 nm, Re(550) represents the in-plane retardation of the λ / 4 plate at a wavelength of 550 nm, and Re(650) represents the in-plane retardation of the λ / 4 plate at a wavelength of 650 nm.

[0095] The phase difference layer used in the present invention can be composed of a single-layer phase difference layer, or it can be composed of two or more phase difference layers stacked by methods such as bonding and successive formation. The phase difference layer referred to herein refers to a layer showing optical anisotropy. As a phase difference layer, for example, at least two different layers of nx, ny and nz can be cited. In addition, nx represents the refractive index in the direction perpendicular to the thickness direction of the phase difference layer (in-plane direction) and the direction giving the maximum refractive index. Ny represents the refractive index in the direction perpendicular to the in-plane direction of the phase difference layer and to the direction of nx. Nz represents the refractive index in the thickness direction of the phase difference layer.

[0096] The material constituting the phase difference layer used in the present invention is not particularly limited, and examples thereof include liquid crystal compounds and polymers. With respect to liquid crystal compounds, the liquid crystal material is oriented to exhibit refractive index anisotropy, thereby forming a phase difference layer. With respect to polymers, a polymer film obtained by casting and coating is made to exhibit refractive index anisotropy by stretching, etc., thereby forming a phase difference layer. In terms of thickness, the phase difference layer used in the present invention is preferably a layer formed using a liquid crystal compound, more preferably a layer formed using a liquid crystal compound having a polymerizable group.

[0097] There is no particular limitation on the type of liquid crystal compound. Generally, liquid crystal compounds can be classified into rod-like types (rod-like liquid crystal compounds) and disc-like types (disc-like liquid crystal compounds) according to their shape. Moreover, liquid crystal compounds can be classified into low molecular weight types and high molecular weight types. High molecules generally refer to substances with a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, by Masao Doi, 2 pages, Iwanami Shoten, 1992). In the present invention, any liquid crystal compound can also be used, but it is preferred to use a rod-like liquid crystal compound or a disc-like liquid crystal compound, more preferably a rod-like liquid crystal compound. Two or more rod-like liquid crystal compounds, two or more disc-like liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disc-like liquid crystal compound can be used.

[0098] Examples of rod-like liquid crystal compounds include those described in claim 1 of Japanese Unexamined Patent Application Publication No. 11-513019 and paragraphs 0026 to 0098 of Japanese Unexamined Patent Application Publication No. 2005-289980.

[0099] Examples of the discotic liquid crystal compound include those described in paragraphs 0020 to 0067 of JP-A-2007-108732 and paragraphs 0013 to 0108 of JP-A-2010-244038.

[0100] The liquid crystal compound preferably has a polymerizable group. That is, the liquid crystal compound is preferably a polymerizable liquid crystal compound. When the liquid crystal compound has a polymerizable group, the alignment state of the liquid crystal compound can be easily fixed by the curing treatment described later.

[0101] The type of the polymerizable group possessed by the liquid crystal compound is not particularly limited, and it is preferably a functional group capable of undergoing an addition polymerization reaction, more preferably a polymerizable ethylenically unsaturated group or a ring-polymerizable group, and still more preferably a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group.

[0102] The number of polymerizable groups possessed by the liquid crystal compound is not particularly limited, and it is preferably 2 or more. The upper limit is not particularly limited, and it is mostly 10 or less.

[0103] The liquid crystal compound may be a liquid crystal compound showing either positive wavelength dispersion or inverse wavelength dispersion. In the case of using a retardation layer that exhibits the characteristics of a broadband λ / 4 plate in a single film form, a liquid crystal compound showing inverse wavelength dispersion is preferred, and a liquid crystal compound having 2 or more polymerizable groups and showing inverse wavelength dispersion is more preferred.

[0104] In this specification, a "liquid crystal compound showing inverse wavelength dispersion" means that when measuring the in-plane retardation (Re) value of an optically anisotropic layer made of this compound at a specific wavelength (visible light range), the relationships of the above formulas (A) and (B) are satisfied.

[0105] Moreover, in this specification, a "liquid crystal compound showing positive wavelength dispersion" means that when measuring the in-plane retardation (Re) value of a retardation layer made of this compound at a specific wavelength (visible light range), the following relationships of formulas (C) and (D) are satisfied.

[0106] Formula (C) Re(450) / Re(550) ≥ 1.00

[0107] Formula (D) Re(650) / Re(550) < 1.00

[0108] As described above, the retardation layer is preferably a layer formed using a liquid crystal compound having a polymerizable group, and more preferably a layer in which the alignment state of the liquid crystal compound having a polymerizable group is fixed.

[0109] The preferable alignment states of the liquid crystal compound having an aggregating group are not particularly limited. For example, homogeneous alignment, vertical alignment, twisted alignment, cholesteric alignment, hybrid alignment (an alignment in which the tilt angle of the liquid crystal compound continuously changes from one surface to the other surface), and tilted alignment (an alignment in which the tilt angle of the liquid crystal compound is constant from one surface to the other surface) can be cited. In addition, the twisted alignment indicates an alignment state in which the liquid crystal compound is twisted around the thickness direction as the rotation axis. When the liquid crystal compound has a twisted alignment and has a specified tilt angle (the tilt angle exceeds 0°), it belongs to the twisted hybrid alignment. In addition, in the present specification, the twisted alignment belongs to a mode in which the twist angle of the liquid crystal compound is less than 360°, and the cholesteric alignment belongs to a mode in which the twist angle of the liquid crystal compound is 360° or more.

[0110] In addition, the "fixed" state is the most typical and preferable mode in which the alignment of the liquid crystal compound is maintained. It is not limited thereto. Specifically, it is more preferably a state in which there is no fluidity in the layer within a temperature range of usually 0 to 50°C and more severe conditions of -3 to 70°C, and the fixed alignment form can be stably maintained without the alignment form being changed by an external field or external force.

[0111] The retardation layer formed using the liquid crystal compound may have regions with different alignment states of the liquid crystal compound in the thickness direction. For example, the retardation layer may have a region in which the homogeneous alignment state of the liquid crystal compound in the thickness direction is fixed and a region in which the twisted alignment state of the liquid crystal compound is fixed.

[0112] The thickness of the retardation layer is not particularly limited, but it is preferably 0.1 to 10.0 μm, more preferably 0.5 to 5.0 μm.

[0113] As a specific example of the structure of a broadband λ / 4 plate, as an example composed of a single-layer retardation layer, examples include the retardation layer using a liquid crystal compound showing inverse wavelength dispersion disclosed in International Publication WO2019 / 160016, Japanese Patent Laid-Open No. 2020-173460, International Publication WO2021 / 157694, etc., and the retardation layer disclosed in International Publication WO2022 / 030308, Japanese Patent Laid-Open No. 2022-184691, etc. This retardation layer has a plurality of regions with different alignment states of liquid crystal compounds along the thickness direction. And, as a structure composed of a stack of two or more retardation layers, examples include the structure combining a λ / 4 retardation layer and a λ / 2 retardation layer disclosed in Japanese Patent Laid-Open No. 2001-108825, Japanese Patent Laid-Open No. 2001-091741, International Publication WO2013 / 137464, etc., and the structure combining a retardation layer with a twisted alignment and other retardation layers disclosed in Japanese Patent Laid-Open No. 2001-021720, Japanese Patent Laid-Open No. 2014-209219, International Publication WO2022 / 255105, etc. And, in order to compensate for the change in retardation with respect to incident light in the tilt direction, other retardation layers such as a positive C-plate and a negative C-plate can be further added.

[0114] 〔Optical interference layer〕

[0115] The retardation film of the present invention includes an optical interference layer. The optical interference layer can be composed of a single-layer optical interference layer, or can be formed by laminating two or more optical interference layers by methods such as bonding and sequential formation.

[0116] The film thickness of the single-layer optical interference layer is preferably in the range of 60 nm to 110 nm or 230 nm to 330 nm, more preferably in the range of 75 nm to 100 nm or 245 nm to 300 nm, and most preferably in the range of 80 nm to 95 nm or 260 nm to 285 nm.

[0117] When using general liquid crystal materials and adhesive layers, their refractive indices are about 1.625 and about 1.5 respectively. Therefore, the refractive index of the optical interference layer is preferably 1.50 to 1.70, more preferably 1.53 to 1.59.

[0118] For an adhesive layer and a retardation layer with arbitrary refractive indices, the preferred range of the optical interference layer can be generalized using the average refractive index of the adhesive layer and the retardation layer, and preferably satisfies the following conditions. That is, when the refractive index of the adhesive layer adjacent to the optical interference layer is nA and the average refractive index of the retardation layer is nL, the refractive index nI of the optical interference layer is preferably (nA × nL) 1 / 2 -0.03 ≤ nI ≤ (nA × nL) 1 / 2+0.03, more preferably (nA × nL) 1 / 2 -0.02 ≤ nI ≤ (nA × nL) 1 / 2 +0.02, most preferably (nA × nL) 1 / 2 -0.01 ≤ nI ≤ (nA × nL) 1 / 2 +0.01

[0119] It is considered that by setting the refractive index of the optical interference layer within this range, the amplitude reflectivities on both surfaces of the optical interference layer can be made to be of the same magnitude, so a large antireflection effect can be obtained. Thus, the reflected light generated by the interface reflection can be suppressed. It is considered that the reflected light whose rotation direction changes due to the interface reflection is one of the causes of ghosting, so by suppressing the interface reflection, the generation of ghosting can be suppressed.

[0120] In addition, the refractive indices of the optical interference layer, the retardation layer, and the adhesive layer can be measured with reference to the methods described in the examples.

[0121] When forming the optical interference layer, it can be formed on the retardation layer, or the optical interference layer can be first formed on the pseudo support and then the retardation layer can be formed thereon. As the material for forming the optical interference layer, a hard coat material made of a crosslinkable monomer, an optically oriented film, and a C-plate using a liquid crystal material can be used. Among them, the optically oriented film also functions to orient the liquid crystal when the retardation layer is formed thereon using a liquid crystal material, so it is more preferable. And the C-plate among them also functions for optical compensation adjustment, so it is more preferable. Moreover, a positive C-plate is more preferable. Here, a positive C-plate means a retardation layer in which Re is substantially zero and Rth has a negative value. A positive C-plate can be obtained, for example, by vertically orienting a rod-like liquid crystal compound. For the details of the manufacturing method of the positive C-plate, reference can be made to, for example, the descriptions in Japanese Patent Application Laid-Open No. 2017-187732, Japanese Patent Application Laid-Open No. 2016-053709, Japanese Patent Application Laid-Open No. 2015-200861, etc.

[0122] [Material for optically oriented film]

[0123] As the optical interference layer, it is also a preferred mode to use a so-called optically oriented film (optically oriented layer) in which an orientation layer is formed by irradiating a material with photo-orientability with polarized light or non-polarized light. It is preferable to impart an orientation restricting force to the optically oriented film by a process of irradiating polarized light from a vertical direction or an inclined direction or a process of irradiating non-polarized light from an inclined direction.

[0124] By using the optically oriented film, a specific liquid crystal compound can be oriented with an excellent symmetry level. Therefore, the retardation layer positive A-plate formed using the optically oriented film is particularly useful for optical compensation in liquid crystal display devices such as an IPS (In-Place-Switching) mode liquid crystal display device that does not require a pretilt angle for driving the liquid crystal.

[0125] As a photo-alignment material for a photo-alignment film, for example, azo compounds described in JP-A-2006-285197, JP-A-2007-076839, JP-A-2007-138138, JP-A-2007-094071, JP-A-2007-121721, JP-A-2007-140465, JP-A-2007-156439, JP-A-2007-133184, JP-A-2009-109831, Japanese Patent No. 3883848, and Japanese Patent No. 4151746; aromatic ester compounds described in JP-A-2002-229039; maleimide and / or alkenyl-substituted nadimide compounds having a photo-alignment unit described in JP-A-2002-265541 and JP-A-2002-317013; photocrosslinkable silane derivatives described in Japanese Patent No. 4205195 and Japanese Patent No. 4205198; photocrosslinkable polyimide, polyamide, or ester described in JP-T-2003-520878, JP-T-2004-529220, and Japanese Patent No. 4162850; compounds capable of photodimerization described in JP-A-9-118717, JP-T-10-506420, JP-T-2003-505561, WO2010 / 150748, JP-A-2013-177561, and JP-A-2014-012823, particularly cinnamate compounds, chalcone compounds, and coumarin compounds. As particularly preferred examples, azo compounds, photocrosslinkable polyimide, polyamide, ester, cinnamate compounds, and chalcone compounds can be mentioned.

[0126] [Material for interlayer photo-alignment film]

[0127] The photo-interference layer preferably contains a material for an interlayer photo-alignment film. Thereby, when a liquid crystal material is coated on the photo-interference layer, the liquid crystal can be aligned, and a structure in which the photo-interference layer is adjacent to the light reflection layer can be formed. As the material for the interlayer photo-alignment film, a photo-alignment polymer described in JP-A-2021-143336 can be used.

[0128] The material for the interlayer photo-alignment film is preferably a compound having a cinnamoyl group. The cinnamoyl compound is preferably contained between the photo-interference layer (preferably a C plate) and the retardation layer. That is, the cinnamoyl compound is preferably contained in a region near the boundary between the photo-interference layer (preferably a C plate) and the retardation layer.

[0129] [Adhesive layer]

[0130] As long as the adhesive layer has a refractive index satisfying the above relational expression, known adhesives, pressure-sensitive adhesives, etc. can be appropriately used. For example, the adhesives and / or pressure-sensitive adhesives used in the laminated optical film described later can be appropriately used.

[0131] As the pressure-sensitive adhesive for the above pressure-sensitive adhesive layer, commercially available pressure-sensitive adhesives can be arbitrarily used. From the viewpoints of thinning and reducing the surface roughness Ra, the thickness is preferably 25 μm or less, more preferably 15 μm or less, and most preferably 6 μm or less. Also, the pressure-sensitive adhesive is preferably less likely to generate outgassing. In particular, in the case of stretching, molding, etc., vacuum processes, heating processes, etc. are sometimes performed, and it is preferably not to generate outgassing under these conditions either.

[0132] As the adhesive for the above adhesive layer, commercially available adhesives, etc. can be arbitrarily used. For example, epoxy resin-based adhesives and acrylic resin-based adhesives can be used.

[0133] From the viewpoints of thinning and reducing the surface roughness Ra of the wire reflection polarizer for the laminated optical film, the thickness of the adhesive is preferably 25 μm or less, more preferably 5 μm or less, and most preferably 1 μm or less. Also, from the viewpoints of thinning the adhesive layer and coating the adhesive on the adherend with a uniform thickness, the viscosity of the adhesive is preferably 300 cP or less, more preferably 100 cP or less.

[0134] Also, in the case where the adherend has surface irregularities, from the viewpoint of reducing the surface roughness Ra of the wire reflection polarizer for the laminated optical film, the pressure-sensitive adhesive and the adhesive can also be selected with appropriate viscoelasticity or thickness so as to be able to embed the surface irregularities of the adhered layer. From the viewpoint of embedding the surface irregularities, the viscosity of the pressure-sensitive adhesive and the adhesive is preferably 50 cP or more. Also, the thickness is preferably thicker than the height of the surface irregularities.

[0135] As a method for adjusting the viscosity of the adhesive, for example, a method of using an adhesive containing a solvent can be cited. In this case, the viscosity of the adhesive can be adjusted by the ratio of the solvent. Also, by drying the solvent after coating the adhesive on the adherend, the thickness of the adhesive can be further reduced.

[0136] In the laminated optical film, from the viewpoints of reducing reflection at the interface and suppressing the generation of ghosts, the pressure-sensitive adhesive or adhesive for bonding each layer is preferably small in refractive index difference from the adjacent layer. Since the retardation layer has birefringence and the refractive indices in the fast axis direction and the slow axis direction are different, when the values obtained by adding the refractive indices in the fast axis direction and the slow axis direction and dividing by 2 are set as the average refractive index n of the liquid crystal layer aveWhen it comes to the refractive index of the adjacent pressure-sensitive adhesive layer or adhesive layer, the difference from n ave is preferably 0.075 or less, more preferably 0.05 or less, and still more preferably 0.025 or less. The refractive index of the pressure-sensitive adhesive or adhesive can be adjusted, for example, by mixing fine particles of titanium oxide and fine particles of zirconium oxide.

[0137] Moreover, regarding the adhesive layer between the respective layers, the thickness of the adhesive layer is also preferably 100 nm or less. If the thickness of the adhesive layer is 100 nm or less, the refractive index difference is not obvious for the light in the visible region, and unnecessary reflection can be suppressed. The thickness of the adhesive layer is more preferably 50 nm or less, and still more preferably 30 nm or less. As a method for forming an adhesive layer with a thickness of 100 nm or less, for example, a method of vapor-depositing a ceramic adhesive such as silicon oxide (SiOx layer) on the bonding surface can be cited. The bonding surface of the bonding member can be subjected to surface modification treatments such as plasma treatment, corona treatment, and saponification treatment before bonding, and a primer layer can be imparted. Moreover, in the case where there are a plurality of bonding surfaces, the type and thickness of the adhesive layer can be adjusted for each bonding surface. Specifically, for example, the adhesive layer with a thickness of 100 nm or less can be provided according to the steps shown in (1) to (3) below.

[0138] (1) Bond the layers to be laminated to a dummy support made of a glass substrate.

[0139] (2) Form a SiOx layer with a thickness of 100 nm or less on both the surface of the layer to be laminated and the surface of the layer to be laminated by vapor deposition or the like. Regarding vapor deposition, SiOx powder can be used as a vapor deposition source and, for example, a vapor deposition apparatus (model ULEYES) manufactured by ULVAC, Inc. can be used. Moreover, it is preferable to perform plasma treatment on the surface of the formed SiOx layer.

[0140] (3) After bonding the formed SiOx layers to each other, peel off the dummy support. Regarding bonding, for example, it is preferably performed at a temperature of 120°C.

[0141] The coating, bonding, or lamination of each layer can be performed in a roll-to-roll (Roll to Roll) manner or in a single-piece manner.

[0142] From the viewpoints of improving productivity or reducing the shaft offset of each layer, the roll-to-roll method is preferred.

[0143] On the other hand, in terms of being suitable for small-lot, multi-variety production and being able to select a special bonding method such as the thickness of the adhesive layer being 100 nm or less as described above, the single-piece method is preferred.

[0144] Further, as a method for applying an adhesive to an adherend, for example, known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing can be cited.

[0145] The retardation film of the present invention may include a support and an alignment layer, etc., but the support and the alignment layer may be a pseudo-support that is peeled off and removed when manufacturing the laminated optical film described later. In the case of using a pseudo-support, by transferring the retardation film to another laminated optical film and then peeling off and removing the pseudo-support, the laminated optical film can be thinned. Furthermore, the retardation of the pseudo-support can eliminate the adverse effect on the polarization degree of transmitted light, so it is preferred.

[0146] The type of the support is not particularly limited, and it is preferably transparent to visible light. For example, films such as cellulose acylates, polycarbonates, polysulfones, polyethersulfones, polyacrylates, polymethacrylates, cyclic polyolefins, polyolefins, polyamides, polystyrenes, and polyesters can be used. Among them, cellulose acylate films, cyclic polyolefins, polyacrylates, or polymethacrylates are preferred. In addition, commercially available cellulose acetate films (for example, "TD80U" and "Z-TAC" manufactured by FUJIFILM Corporation, etc.) can also be used.

[0147] In the case where the support is a pseudo-support, from the viewpoint of preventing breakage during peeling, a support with high tear strength is preferred. For example, polycarbonate and polyester-based films are preferred.

[0148] Further, from the viewpoint of suppressing the adverse effect on the polarization degree of transmitted light, the support preferably has a small retardation. Specifically, the magnitude of Re at 550 nm is preferably 10 nm or less, and the absolute value of the magnitude of Rth is preferably 50 nm or less. Moreover, even when the support is used as the above-mentioned pseudo-support, from the aspect of quality inspection of the retardation film and the laminated optical film in the manufacturing process of the laminated optical film described later, it is preferred that the retardation of the pseudo-support is small.

[0149] Furthermore, in terms of minimizing the influence on various sensors that use near-infrared light as a light source, such as eye tracking, expression recognition, and iris authentication, which are assembled into optical systems such as virtual reality display devices and electronic viewfinders, it is preferred that the retardation film for the laminated optical film described later is transmissive to near-infrared light.

[0150] [Laminated Optical Film]

[0151] The laminated optical film of the present invention preferably has at least a retardation film that converts circularly polarized light into linearly polarized light and a linear reflection polarizer in this order.

[0152] As the above-mentioned retardation film, the above-mentioned retardation film is used. The preferred embodiment of the retardation film is as described above.

[0153] The linear reflection polarizer is preferably disposed on the side of the retardation layer opposite to the optical interference layer.

[0154] As a preferred use example of the laminated optical film of the present invention, a virtual reality display device using the laminated optical film of the present invention is cited, and the action of the laminated optical film of the present invention is described in detail.

[0155] Figure 3 It is a schematic diagram of a virtual reality display device using the laminated optical film of the present invention. In Figure 3 In the virtual reality display device of the shown embodiment, a laminated optical film 100 having the above-mentioned retardation film and linear reflection polarizer, a half mirror 300, a circular polarizer 400, and an image display panel 500 are sequentially arranged from the visual recognition side. As Figure 3 shown, the light 1000 emitted from the image display panel 500 passes through the circular polarizer 400 to become circularly polarized light and passes through the half mirror 300. Then, after passing through the retardation film of the laminated optical film 100 of the present invention and being converted into linearly polarized light parallel to the reflection axis of the linear reflection polarizer, it is reflected by the linear reflection polarizer. Then, it is reflected by the half mirror 300 again and incident on the laminated optical film 100 again. At this time, the polarization state of the light 1000 becomes circularly polarized light with a rotation direction opposite to that of the circularly polarized light when it is first incident on the laminated optical film 100 due to being reflected by the half mirror. If the light of this polarization state passes through the retardation film of the laminated optical film, it is converted into linearly polarized light parallel to the transmission axis of the linear reflection polarizer. Thus, the light 1000 passes through the laminated optical film 100 and is visually recognized by the user. Furthermore, when the light 1000 is reflected by the half mirror 300, since the half mirror has a concave mirror shape, the image displayed on the image display panel 500 is enlarged, and the user can visually recognize the enlarged virtual image. The above mechanism is called a reciprocating optical system or a folding-back optical system, etc.

[0156] On the other hand, Figure 4 It is a schematic diagram for explaining the occurrence of ghosting in the virtual reality display device shown in Figure 3 more specifically, it is a schematic diagram showing the case where, in the virtual reality display device, when the light 2000 is first incident on the laminated optical film 100, it is not reflected to the half mirror but passes through and becomes leakage light. As Figure 4 shown, when the light 2 000 is first incident on the laminated optical film 100, in the case where it passes through without being reflected to the half mirror and leakage light is generated, from Figure 4 it can be seen that the user will visually recognize an unenlarged image. This image is called ghosting, etc., and it is required to suppress it.

[0157] There are mainly two reasons for the light leakage (ghosting). One is caused by the phase difference in the reflective polarizer, and the other is the light leakage (ghosting) caused by the change in the rotation direction due to the interface reflection as described before in Figure 6 .

[0158] Since the laminated optical film 100 of the present invention has a high degree of polarization, it is possible to reduce the leakage of transmitted light (i.e., ghosting) when light first enters the laminated optical film 100.

[0159] Moreover, since the laminated optical film 100 of the present invention also has a high degree of polarization for transmitted light, it is possible to increase the transmittance when light enters the laminated optical film 100 for the second time, and it is possible to increase the brightness of the virtual image and thereby suppress the coloring of the virtual image.

[0160] As Figure 3 and Figure 4 shown, the laminated optical film 100 is preferably curved. Regarding the structure in which the laminated optical film 100 is curved, the laminated optical film 100 itself can be formed into a curved surface shape, or, as Figure 8 shown, it can be curved by being laminated on the surface of a component having a curved surface such as a lens 600.

[0161] An example of the layer structure of the laminated optical film 100 of the present invention is shown in Figure 5 . Figure 5 In the laminated optical film 100 shown, a retardation film 11, an adhesive layer 101, a linear reflective polarizer 102, an adhesive layer 103, and a linear polarizer 104 are sequentially arranged. As described above, the retardation film 11 has a retardation layer 21, an optical interference layer 22, and an adhesive layer 23. The linear polarizer 104 is preferably an absorption type linear polarizer.

[0162] The laminated optical film of the present invention sequentially has a retardation layer 11 that converts circularly polarized light into linearly polarized light, a linear reflective polarizer 102, and a linear polarizer 104, so it is possible to absorb the transmitted light from the linear reflective polarizer 102 through the linear polarizer. Therefore, it is possible to increase the degree of polarization of the transmitted light.

[0163] Moreover, the surface roughness Ra of the laminated optical film of the present invention is preferably 100 nm or less. If Ra is small, for example, when the laminated optical film is used in a virtual reality display device or the like, the clarity of the image can be improved. The inventor speculates that when light is reflected in the laminated optical film, if there are irregularities, it will cause the deviation of the reflection angle of the reflected light, image distortion, blurring, etc. The Ra of the laminated optical film is more preferably 50 nm or less, further preferably 30 nm or less, and particularly preferably 10 nm or less.

[0164] Moreover, the laminated optical film of the present invention is produced by laminating a plurality of layers. According to the research of the present inventors, it has been found that when other layers are laminated on a layer having irregularities, the irregularities may be amplified. Therefore, in the laminated optical film of the present invention, it is preferable that the Ra of all layers is small. The Ra of each layer of the laminated optical film of the present invention is preferably 50 nm or less, more preferably 30 nm or less, and still more preferably 10 nm or less.

[0165] Moreover, from the viewpoint of improving the image clarity of the reflected image, in particular, it is preferable that the Ra of the linear reflection polarizer is small.

[0166] The surface roughness Ra can be measured, for example, using a non-contact surface / layer cross-sectional shape measurement system VertScan (manufactured by Ryoka Systems Inc.). Since Vertscan is a surface shape measurement method using the phase of the reflected light from the specimen, when measuring a linear reflection polarizer, there may be a case where the reflected light from the inside of the film overlaps and the surface shape cannot be accurately measured. In this case, a metal layer can be formed on the surface of the specimen to increase the surface reflectivity and thereby suppress the reflection from the inside. As a method of forming a metal layer on the surface of the specimen, for example, a sputtering method can be used. As a material for sputtering, Au, Al, Pt, etc. can be used.

[0167] The laminated optical film of the present invention preferably has a small number of point defects per unit area. Since the laminated optical film of the present invention is produced by laminating a plurality of layers, it is preferable that the number of point defects in each layer is also small in order to reduce the number of point defects in the entire laminated optical film. Specifically, the number of point defects in each layer is preferably 20 or less, more preferably 10 or less, and still more preferably 1 or less per 1 square meter. As for the entire laminated optical film, the number of point defects is preferably 100 or less, more preferably 50 or less, and still more preferably 5 or less per 1 square meter.

[0168] Point defects can cause a decrease in the degree of polarization of transmitted light and a decrease in image clarity, etc., so it is preferable that there are few point defects.

[0169] Here, point defects include foreign matters, scratches, dirt, film thickness variations, poor alignment of liquid crystal compounds, etc.

[0170] Moreover, regarding the number of the above-mentioned point defects, it is preferably as follows: The counting is preferably the number of point defects having a size of 100 μm or more, more preferably 30 μm or more, and most preferably 10 μm or more.

[0171] In addition, various sensors that use near-infrared light as a light source, such as eye tracking, expression recognition, and iris authentication, are sometimes assembled in optical systems such as virtual reality display devices and electronic viewfinders. In order to minimize the impact on the sensors, it is preferable that the laminated optical film of the present invention is transmissive to near-infrared light.

[0172] [Polarizer]

[0173] The polarizer used for the laminated optical film of the present invention is preferably an absorption-type polarizer. The absorption-type polarizer absorbs linearly polarized light in the absorption axis direction of the incident light and transmits linearly polarized light in the transmission axis direction. As the polarizer, a general polarizer can be used. For example, it can be a polarizer obtained by dyeing polyvinyl alcohol or other polymer resins with a dichroic substance and stretching it to orient the dichroic substance, or it can be a polarizer obtained by orienting a dichroic substance by using the orientation of a liquid crystal compound. From the viewpoints of availability and improving the degree of polarization, a polarizer obtained by dyeing polyvinyl alcohol with iodine and stretching it is preferred.

[0174] The thickness of the polarizer is preferably 10 μm or less, more preferably 7 μm or less, and further preferably 5 μm or less. If the polarizer is thin, cracks and breaks in the film can be prevented when stretching or molding the laminated optical film.

[0175] In addition, the single-sheet transmittance of the polarizer is preferably 40% or more, more preferably 42% or more. And the degree of polarization is preferably 90% or more, more preferably 95% or more, and further preferably 99% or more. In addition, in this specification, the single-sheet transmittance and the degree of polarization of the polarizer are measured using an automatic polarization film measuring device: VAP-7070 (manufactured by JASCO Corporation).

[0176] In addition, the direction of the transmission axis of the polarizer is preferably the same as the polarization axis direction of the light converted into linearly polarized light by the retardation layer. For example, when the retardation layer is a layer having a retardation of 1 / 4 wavelength, the angle formed by the transmission axis of the polarizer and the slow axis of the retardation layer is preferably approximately 45°.

[0177] The polarizer used for the laminated optical film of the present invention is also preferably a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic substance. A polarizer containing a liquid crystal compound and a dichroic substance can make its thickness thinner and is not likely to generate cracks and breaks even when stretched and molded, etc., so it is preferred. The thickness of the light-absorbing anisotropic layer is not particularly limited, and from the viewpoint of thinning, it is preferably 0.1 to 8 μm, more preferably 0.3 to 5 μm.

[0178] Regarding a linear polarizer containing a liquid crystal compound and a dichroic substance, for example, it can be produced by referring to Japanese Patent Application Laid-Open No. 2020-023153 and the like. From the viewpoint of improving the degree of polarization of the linear polarizer, the degree of orientation of the dichroic substance in the light absorption anisotropic layer is preferably 0.95 or more, more preferably 0.97 or more.

[0179] The liquid crystal compound contained in the light absorption anisotropic layer-forming composition for forming the light absorption anisotropic layer is preferably a liquid crystal compound that does not exhibit dichroism in the visible region.

[0180] As the liquid crystal compound, either a low-molecular liquid crystal compound or a high-molecular liquid crystal compound can be used. Here, the "low-molecular liquid crystal compound" refers to a liquid crystal compound that does not have a repeating unit in its chemical structure. And the "high-molecular liquid crystal compound" refers to a liquid crystal compound that has a repeating unit in its chemical structure.

[0181] As the high-molecular liquid crystal compound, for example, a thermotropic liquid crystal polymer described in Japanese Patent Application Laid-Open No. 2011-237513 can be cited. And the high-molecular liquid crystal compound preferably has a crosslinkable group (for example, an acryloyl group and a methacryloyl group) at its terminal.

[0182] The liquid crystal compound can be used alone or in combination of two or more. It is also preferred to use a high-molecular liquid crystal compound and a low-molecular liquid crystal compound in combination.

[0183] The content of the liquid crystal compound is preferably 25 to 2000 parts by mass, more preferably 33 to 1000 parts by mass, and further preferably 50 to 500 parts by mass with respect to 100 parts by mass of the content of the dichroic substance in the present composition. By the content of the liquid crystal compound being within the above range, the degree of orientation of the polarizer is further improved.

[0184] The dichroic substance contained in the light absorption anisotropic layer-forming composition for forming the light absorption anisotropic layer is not particularly limited, and examples include visible light absorption substances (dichroic pigments), ultraviolet absorption substances, infrared absorption substances, nonlinear optical substances, carbon nanotubes, etc., and conventionally known dichroic substances (dichroic pigments) can be used.

[0185] In the present invention, two or more dichroic substances can be used in combination. For example, from the viewpoint of obtaining a high degree of polarization in a wider wavelength range, it is preferred to use in combination at least one dichroic substance having a maximum absorption wavelength in the range of 370 to 550 nm and at least one dichroic substance having a maximum absorption wavelength in the range of 500 to 700 nm.

[0186] When the linear polarizer is composed of a light absorption anisotropic layer containing a liquid crystal compound and a dichroic substance, the linear polarizer may include a support and an alignment layer, etc. The support and the alignment layer may be a pseudo-support that is peeled off and removed when manufacturing the laminated optical film. When using a pseudo-support, by transferring the light absorption anisotropic layer to another laminate and then peeling off and removing the pseudo-support, the laminated optical film can be thinned. Furthermore, the retardation of the pseudo-support can eliminate the adverse effects on the degree of polarization of the transmitted light, so it is preferred.

[0187] The type of the support is not particularly limited, and it is preferably transparent to visible light. For example, the same support as that used for the above-mentioned retardation layer can be used. The preferred mode of the support for the linear polarizer is the same as the preferred mode of the support used for the above-mentioned retardation layer.

[0188] Moreover, in order to minimize the influence on various sensors that use near-infrared light as a light source, such as eye tracking, expression recognition, and iris authentication, which are assembled into optical systems such as virtual reality display devices and electronic viewfinders, it is preferred that the linear polarizer for the laminated optical film of the present invention is transmissive to near-infrared light.

[0189] 〔Other functional layers〕

[0190] In addition to the retardation film, the linear reflection polarizer, and the linear polarizer, the laminated optical film of the present invention may also have other functional layers.

[0191] Moreover, in order to minimize the influence on various sensors that use near-infrared light as a light source, such as eye tracking, expression recognition, and iris authentication, which are assembled into optical systems such as virtual reality display devices and electronic viewfinders, other functional layers are preferably transmissive to near-infrared light.

[0192] <Positive C plate>

[0193] The laminated optical film of the present invention also preferably further has a positive C plate. Here, the positive C plate refers to a retardation layer in which Re is substantially zero and Rth has a negative value. The positive C plate can be obtained, for example, by vertically aligning a rod-shaped liquid crystal compound. For the detailed content of the manufacturing method of the positive C plate, reference can be made to, for example, the descriptions in Japanese Patent Application Laid-Open No. 2017-187732, Japanese Patent Application Laid-Open No. 2016-053709, Japanese Patent Application Laid-Open No. 2015-200861, etc.

[0194] The positive C plate functions as an optical compensation layer for improving the degree of polarization of the transmitted light for light incident from an oblique direction. The positive C plate can be provided at any position of the laminated optical film, and multiple positive C plates can be provided.

[0195] The positive C-plate can be adjacent to the retardation film or disposed inside the retardation film. When, for example, a layer formed by immobilizing a rod-like liquid crystal compound is used as the retardation film, the retardation layer has a positive Rth. At this time, for the retardation layer, when light is incident from an oblique direction, the polarization state of the transmitted light sometimes changes due to the action of Rth, and the degree of polarization of the transmitted light decreases. If a positive C-plate is provided inside or near the retardation layer, the change in the polarization state of the obliquely incident light can be further suppressed, and the decrease in the degree of polarization of the transmitted light can be further suppressed. As a result, ghosting can be further suppressed, so it is preferred. According to the research of the present inventors, the positive C-plate is preferably disposed between the lens and the retardation film, but it can also be disposed between the retardation film and the linear reflection polarizer, or can be provided at other positions. At this time, Re(550) of the positive C-plate is preferably about 10 nm or less, and Rth(550) is preferably -90 to -40 nm.

[0196] <Anti-reflection layer>

[0197] The laminated optical film of the present invention also preferably has an anti-reflection layer on its surface. The laminated optical film of the present invention has the function of reflecting specific circularly polarized light and transmitting circularly polarized light orthogonal to the specific circularly polarized light. The reflection on the surface of the laminated optical film usually includes the reflection of unintended polarized light, which sometimes reduces the degree of polarization of the transmitted light. Therefore, the laminated optical film preferably has an anti-reflection layer on its surface. The anti-reflection layer can be provided only on one surface of the laminated optical film, or can be provided on both surfaces.

[0198] The type of the anti-reflection layer is not particularly limited. From the viewpoint of further reducing the reflectance, a moth-eye film or an AR (Anti-Reflective) film is preferred. The moth-eye film and the AR film can use known films.

[0199] Moreover, in the case of stretching or molding the laminated optical film, since the moth-eye film can maintain high anti-reflection performance even when the film thickness changes due to stretching, it is preferred. Further, the anti-reflection layer includes a support. In the case of stretching and molding, etc., from the viewpoint of facilitating stretching and molding, etc., the peak temperature of the glass transition temperature Tg of the above support is preferably 170 °C or lower, and more preferably 130 °C or lower. Specifically, for example, a PMMA film or the like is preferred.

[0200] <Second retardation layer>

[0201] The laminated optical film of the present invention also preferably further has a second retardation layer. For example, it can sequentially include a retardation film, a linear reflection polarizer, a linear polarizer, and a second retardation layer.

[0202] The second retardation layer is preferably a layer that converts linearly polarized light into circularly polarized light. For example, it is preferably a retardation layer having a Re of 1 / 4 wavelength. The reason therefor will be described below.

[0203] The light that is incident on the laminated optical film from the retardation film side and passes through the linear reflection polarizer and the linear polarizer becomes linearly polarized light, and a part of it is reflected on the outermost surface on the linear polarizer side and then exits again from the surface on the retardation film side. Such light is unnecessary reflected light and may be the main cause of reducing the degree of polarization of the reflected light. Therefore, it is preferably reduced. Therefore, in order to suppress the reflection on the outermost surface on the linear polarizer side, there is a method of laminating an antireflection layer. However, when the laminated optical film is used by being adhered to a medium such as glass and plastic, even if an antireflection layer is provided on the adhesion surface of the laminated optical film, the reflection on the medium surface cannot be suppressed, and thus it is difficult to obtain an antireflection effect.

[0204] On the other hand, when a second retardation layer that converts linearly polarized light into circularly polarized light is provided, the light that reaches the outermost surface on the linear polarizer side becomes circularly polarized light and is converted into orthogonally circularly polarized light when reflected on the outermost surface of the medium. Then, when it passes through the second retardation layer again and reaches the linear polarizer, the light becomes linearly polarized light in the absorption axis azimuth of the linear polarizer and is absorbed by the linear polarizer. Thereby, unnecessary reflection can be prevented.

[0205] From the viewpoint of more effectively suppressing unnecessary reflection, the second retardation layer preferably substantially has inverse wavelength dispersion.

[0206] <Support>

[0207] The laminated optical film of the present invention may further have a support (resin substrate). The support can be provided at any position. For example, when the retardation film, the linear reflection polarizer, or the linear polarizer is a film used by being transferred from a pseudo support, the support can be used as its transfer target (Target).

[0208] The type of the support is not particularly limited, and it is preferably transparent to visible light. For example, films such as cellulose acylates, polycarbonates, polysulfones, polyethersulfones, polyacrylates, polymethacrylates, cyclic polyolefins, polyolefins, polyamides, polystyrenes, and polyesters can be used. Among them, cellulose acylate films, cyclic polyolefins, polyacrylates, or polymethacrylates are preferred. In addition, commercially available cellulose acetate films (for example, "TD80U", "Z-TAC", etc. manufactured by FUJIFILM Corporation) can also be used.

[0209] Further, from the viewpoints of suppressing adverse effects on the degree of polarization of transmitted light and facilitating optical inspection of the laminated optical film, it is preferable that the retardation of the support is small. Specifically, the magnitude of Re is preferably 10 nm or less, and the absolute value of the magnitude of Rth is preferably 50 nm or less.

[0210] In the case of stretching and molding the laminated optical film of the present invention, etc., the peak temperature of the loss tangent tanδ of the support (resin substrate) is preferably 170°C or less. From the viewpoint of being able to perform molding at a low temperature, the peak temperature of tanδ is preferably 150°C or less, and more preferably 130°C or less.

[0211] Here, the method for measuring tanδ is described. Using a dynamic viscoelasticity measuring device (DVA-200 manufactured by IT KeisokuSeigyo Co., Ltd.), for a film specimen that has been conditioned at a temperature of 25°C and a humidity of 60% RH for 2 hours or more in advance, E” (loss elastic modulus) and E’ (storage elastic modulus) are measured under the following conditions, and the value of tanδ (= E” / E’) is obtained therefrom.

[0212] Device: DVA-200 manufactured by IT Keisoku Seigyo Co., Ltd.

[0213] Specimen: 5 mm, length 50 mm (gap 20 mm)

[0214] Measurement conditions: Tensile mode

[0215] Measurement temperature: -150°C to 220°C

[0216] Temperature increase condition: 5°C / min

[0217] Frequency: 1 Hz

[0218] In addition, usually in optical applications, a resin substrate that has been subjected to a stretching treatment is mostly used, and the peak temperature of tanδ often becomes high due to the stretching treatment. For example, the peak temperature of tanδ of a TAC (triacetyl cellulose) substrate (TG40, manufactured by FUJIFILM Corporation) is 180°C or higher.

[0219] The support with a peak temperature of tanδ below 170°C is not particularly limited, and various resin substrates can be used. For example, polyolefins such as polyethylene, polypropylene, and norbornene-based polymers can be mentioned; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; acrylic resins such as polymethyl acrylate and polyacrylate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyether ketone; polyphenylene sulfide and polyphenylene oxide. Among them, from the viewpoints of being easily available in the market or having excellent transparency, cyclic olefin-based resins, polyethylene terephthalate, or acrylic resins are preferred, and cyclic olefin-based resins or polymethyl acrylate are particularly preferred.

[0220] As commercially available resin substrates, TECHNOLLOY S001G, TECHNOLLOY S014G, TECHNOLLOY S000, TECHNOLLOY C001, TECHNOLLOY C000 (Copyright Sumika Acryl Co., Ltd), Lumirror U type, Lumirror FX10, Lumirror SF20 (TORAY INDUSTRIES, INC.), HK-53A (HYNT. Co.), TEFLEX FT3 (Teijin DuPont Films Japan Ltd.), ESSINA, and SCA40 (SEKISUICHEMICAL CO., LTD.), ZEO NOR film (ZEON CORPORATION.), ARTON film (JSR Corporation), etc. can be mentioned.

[0221] The thickness of the support is not particularly limited, preferably 5 to 300 μm, more preferably 5 to 100 μm, and further preferably 5 to 30 μm.

[0222] Furthermore, the laminated optical film may have layers other than the above-mentioned layers. For example, as layers other than the above, a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive described later, a bonding layer formed of an adhesive described later, and a refractive index adjustment layer can be mentioned.

[0223] Moreover, a refractive index adjustment layer with a refractive index difference between the fast axis direction and the slow axis direction smaller than that of the retardation layer can be provided between the retardation layer and the pressure-sensitive adhesive or between the retardation layer and the adhesive. In this case, it is preferred that the refractive index adjustment layer has a layer formed by fixing the alignment state of a cholesteric liquid crystal. By having the refractive index adjustment layer, interface reflection can be further suppressed, and the generation of ghost images can be further suppressed. Furthermore, it is more preferred that the average refractive index of the refractive index adjustment layer is smaller than the average refractive index of the retardation layer.

[0224] 〔Bonding method for each layer〕

[0225] The laminated optical film of the present invention is a laminate composed of multiple layers. Each layer can be bonded by any bonding method. For example, pressure-sensitive adhesives and adhesives can be used.

[0226] As the pressure-sensitive adhesive, commercially available pressure-sensitive adhesives can be arbitrarily used. From the viewpoints of thinning and reducing the surface roughness Ra of the laminated optical film, the thickness is preferably 25 μm or less, more preferably 15 μm or less, and most preferably 6 μm or less. Also, the pressure-sensitive adhesive is preferably less likely to generate outgassing. In particular, in cases such as stretching and forming, vacuum processes and heating processes are sometimes performed, and it is preferably not to generate outgassing under these conditions either.

[0227] As the adhesive, commercially available adhesives can be arbitrarily used. For example, epoxy resin-based adhesives and acrylic resin-based adhesives can be used.

[0228] From the viewpoints of thinning and reducing the surface roughness Ra of the laminated optical film, the thickness of the adhesive is preferably 25 μm or less, more preferably 5 μm or less, and most preferably 1 μm or less. Also, from the viewpoints of thinning the adhesive layer and coating the adhesive on the adherend with a uniform thickness, the viscosity of the adhesive is preferably 300 cP or less, more preferably 100 cP or less, and further preferably 10 cP or less.

[0229] Also, in the case where the adherend has surface irregularities, from the viewpoint of reducing the surface roughness Ra of the laminated optical film, the pressure-sensitive adhesive and the adhesive can also select appropriate viscoelasticity or thickness to be able to embed the surface irregularities of the layer to be bonded. From the viewpoint of embedding the surface irregularities, the viscosity of the pressure-sensitive adhesive and the adhesive is preferably 50 cP or more. Also, the thickness is preferably thicker than the height of the surface irregularities.

[0230] As a method for adjusting the viscosity of the adhesive, for example, a method of using an adhesive containing a solvent can be cited. In this case, the viscosity of the adhesive can be adjusted by the ratio of the solvent. Also, by drying the solvent after coating the adhesive on the adherend, the thickness of the adhesive can be further reduced.

[0231] In the laminated optical film, from the viewpoints of reducing unnecessary reflection and suppressing the reduction of the polarization degree of transmitted light and reflected light, the pressure-sensitive adhesive or adhesive used for bonding each layer is preferably small in refractive index difference from the adjacent layer. Specifically, the refractive index difference between adjacent layers is preferably 0.1 or less, more preferably 0.05 or less, and further preferably 0.01 or less. The refractive index of the pressure-sensitive adhesive or adhesive can be adjusted, for example, by mixing fine particles of titanium oxide and fine particles of zirconium oxide.

[0232] Further, the phase difference layer, the wire reflection polarizer, and the linear polarizer sometimes have in-plane refractive index anisotropy, and preferably the refractive index difference from the adjacent layer is 0.05 or less in all directions in the plane. Therefore, the pressure-sensitive adhesive or the adhesive may have in-plane refractive index anisotropy.

[0233] Further, regarding the adhesive layer between the layers, the thickness of the adhesive layer is also preferably 100 nm or less. If the thickness of the adhesive layer is 100 nm or less, the refractive index difference is not obvious for the light in the visible region, and reflection at the interface can be suppressed. The thickness of the adhesive layer is more preferably 50 nm or less. As a method for forming an adhesive layer with a thickness of 100 nm or less, for example, a method of vapor-depositing a ceramic adhesive such as silicon oxide (SiOx layer) on the bonding surface can be cited. The bonding surface of the bonding member can be subjected to surface modification treatments such as plasma treatment, corona treatment, and saponification treatment, or a primer layer can be applied before bonding. And, in the case where there are a plurality of bonding surfaces, the type or thickness of the adhesive layer can be adjusted for each bonding surface. Specifically, for example, an adhesive layer with a thickness of 100 nm or less can be provided according to the steps shown in (1) to (3) below.

[0234] (1) Bond the layers to be laminated to a dummy support made of a glass substrate.

[0235] (2) Form a SiOx layer with a thickness of 100 nm or less on both the surface of the layer to be laminated and the surface of the layer to be laminated by vapor deposition or the like. Regarding vapor deposition, SiOx powder can be used as a vapor deposition source and, for example, a vapor deposition apparatus (model ULEYES) manufactured by ULVAC, Inc. can be used. And, it is preferable to perform plasma treatment on the surface of the formed SiOx layer.

[0236] (3) After bonding the formed SiOx layers to each other, peel off the dummy support. Regarding bonding, for example, it is preferably performed at a temperature of 120°C.

[0237] Coating, bonding, or laminating of each layer can be performed in a roll-to-roll manner or in a single-piece manner. From the viewpoint of improving productivity or reducing the shaft offset of each layer, a roll-to-roll method is preferred.

[0238] On the other hand, in terms of being suitable for small-lot, multi-variety production or being able to select a special bonding method such as the thickness of the adhesive layer being 100 nm or less as described above, a single-piece method is preferred.

[0239] And, as a method for applying the adhesive to the adherend, for example, known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing can be cited.

[0240] [Direct coating of each layer]

[0241] It is also preferable that there is no adhesive layer between the layers of the laminated optical film of the present invention. When forming a layer, coating can be directly performed on an already formed adjacent layer, so that an adhesive layer can be omitted. Further, when one or both of the adjacent layers are layers containing a liquid crystal compound, it is preferable that the alignment direction of the liquid crystal compound continuously changes at the interface to reduce the refractive index difference in all in-plane directions. For example, it is also possible to directly coat a retardation layer containing a liquid crystal compound on a linear polarizer containing a liquid crystal compound and a dichroic substance, and based on the alignment restricting force of the liquid crystal compound of the linear polarizer, align the liquid crystal compound of the retardation layer in a continuous manner at the interface.

[0242] [Lamination order of each layer]

[0243] The laminated optical film of the present invention is composed of multiple layers, and the order of the steps of laminating these layers is not particularly limited and can be arbitrarily selected.

[0244] For example, in the case of transferring a functional layer from a film composed of a pseudo support and a functional layer, wrinkles and cracks during transfer can be prevented by adjusting the lamination order so that the thickness of the film to be transferred becomes 10 μm or more.

[0245] Further, from the viewpoint of reducing the surface roughness Ra of the laminated optical film, when laminating other layers on a layer with large surface irregularities, since the surface irregularities may further increase, it is preferable to laminate the layers in order starting from the layer with a small surface roughness Ra.

[0246] Moreover, the lamination order can also be selected from the viewpoints of improving the manufacturing yield of the laminated optical film or reducing costs.

[0247] [Application of the laminated optical film of the present invention]

[0248] For example, as described in Patent Documents 4 to 5, the laminated optical film of the present invention can be used as a reflective polarizer assembled into a vehicle-mounted rearview mirror, a virtual reality display device, an electronic viewfinder, etc. In particular, in a virtual reality display device and an electronic viewfinder having a reciprocating optical system in which light is reflected and reciprocated between a reflective polarizer and a semi-reflective mirror, the laminated optical film of the present invention is very useful from the viewpoint of improving the clarity of the displayed image. Moreover, a virtual reality display device and an electronic viewfinder having a reciprocating optical system sometimes have optical films such as an absorption-type polarizer and a circular polarizer in addition to the reflective polarizer, but by also using the components for the laminated optical film of the present invention for optical films other than the above-mentioned reflective polarizer, the clarity of the displayed image can be further improved.

[0249] <Optical article>

[0250] One mode of the optical article of the present invention is a compound lens composed of a lens and the laminated optical film of the present invention. A semi-reflective mirror may be formed on one surface of the lens. As the lens, a convex lens or a concave lens can be used. As the convex lens, a biconvex lens, a plano-convex lens, or a convex meniscus lens can be used. As the concave lens, a biconcave lens, a plano-concave lens, or a concave meniscus lens can be used. As the lens for a virtual reality display device, in order to widen the viewing angle, a convex meniscus lens or a concave meniscus lens is preferred. Furthermore, in terms of being able to suppress chromatic aberration less, a concave meniscus lens is more preferred. As the material of the lens, materials transparent to visible light such as glass, crystal, and plastic can be used. Birefringence of the lens causes iridescence or light leakage, so it is preferably small in birefringence, and more preferably a zero-birefringence material. The laminated optical film of the present invention for the optical article of the present invention may be flat or curved, but in terms of less image distortion or aberration, a curved surface is preferred.

[0251] <Virtual Reality Display Device>

[0252] One mode of the virtual reality display device includes at least an image display device that emits polarized light and a compound lens as the optical article of the present invention. And, in addition to this, additional optical components such as a semi-reflective mirror and a diopter adjustment lens may also be provided.

[0253] <Image Display Device>

[0254] As the image display device for the present invention, a known image display device can be used. For example, display devices in which self-luminous fine light-emitting bodies are arranged on a transparent substrate such as an organic electroluminescence display device, an LED (Light Emitting Diode) display device, and a micro-LED display device can be exemplified. These self-luminous display devices usually have a (circular) polarizing plate attached to the display surface to prevent reflection of the display surface. Therefore, the emitted light is polarized. And, as other image display devices, a liquid crystal display device is exemplified. The liquid crystal display device also has a polarizing plate on the surface, so the emitted light is polarized. In the following description, the organic electroluminescence display device is also referred to as an OLED. OLED is an abbreviation for "Organic Light Emitting Diode".

[0255] <Molding Method>

[0256] The laminated optical film of the present invention can be used in a flat form or can be molded into an arbitrary shape for use. Here, the laminated optical film is referred to as an optical film, and the molding method is described. The molding method of the optical film includes: a step of heating the optical film; a step of pressing the optical film onto a mold and deforming it along the shape of the mold; and a step of cutting the optical film.

[0257] [Process of heating the optical film]

[0258] As a method of heating the optical film, heating by contact with a heated solid, heating by contact with a heated liquid, heating by contact with a heated gas, heating by irradiating infrared rays, heating by irradiating microwaves, etc. can be used. However, heating by remotely irradiating infrared rays capable of heating immediately before molding is preferred.

[0259] The wavelength of the infrared rays for heating is preferably from 1.0 μm to 30.0, and more preferably from 1.5 μm to 5 μm. As the IR light source, a near-infrared lamp heater in which a tungsten wire is enclosed in a quartz tube, a wavelength control heater having a multi-quartz tube structure and a mechanism for air-cooling a part between the quartz tubes, etc. can be used. Also, by applying an infrared irradiation amount distribution on the optical film, the physical property values during molding can be controlled according to the purpose. As a method of applying the intensity distribution, a method of making the arrangement density of the IR light sources sparse or dense and a method of arranging a filter that patterns the transmittance of infrared light between the IR light source and the optical film can be used. As a filter that patterns the transmittance, a filter obtained by vapor-depositing a metal on glass, a filter that infraredizes the reflection band of a cholesteric liquid crystal layer, a filter that infraredizes the reflection band in a dielectric multilayer film, and an ink that absorbs infrared rays, etc. are used. Regarding the temperature control of the optical film, it is controlled by the intensity of infrared irradiation, and is controlled by the infrared irradiation time or the illuminance of infrared irradiation. The temperature of the optical film can be monitored using a non-contact radiation thermometer, a thermocouple, etc., and molded at the target temperature.

[0260] [Process of pressing the optical film onto a mold and deforming it along the shape of the mold]

[0261] As a method of pressing the optical film onto a mold and deforming it along the shape of the mold, decompression and pressurization of the molding space are used. Also, a method of pressing into the mold can be used.

[0262] [Process of cutting the optical film]

[0263] As a method of cutting the molded optical film into an arbitrary shape, a cutter, scissors, a cutting plotter, a laser cutting machine, etc. can be used.

[0264] <Molding device>

[0265] Regarding one form of a molding apparatus, it is composed of a mold box 1 having an opening in the upper direction and a mold box 2 having an opening in the lower direction. In order to form a molding space, the opening of mold box 1 is directly docked with the opening of mold box 2 or via other jigs, thereby forming a sealed molding space. In the molding space, a mold of the shape to be molded (also referred to as an adherend) and a film to be molded are arranged. The film to be molded serves as a separator, dividing the molding space composed of mold box 1 and mold box 2 into two spaces. The above-mentioned mold is arranged on the side of mold box 1 below the film to be molded. Moreover, a plurality of heating elements for heating the film to be molded are dispersedly arranged in the vacuum molding apparatus. The heating elements can be arranged in the molding space or outside the molding space and irradiate the film to be molded through a transparent window.

[0266] Examples

[0267] Hereinafter, examples are given to further specifically illustrate the features of the present invention. In addition, as long as the gist of the present invention is not departed from, the materials, usage amounts, ratios, treatment contents, treatment steps, etc. shown below can be appropriately changed. And, as long as the gist of the present invention is not departed from, it can also be set to a structure other than the structure shown below.

[0268] [Preparation of coating liquid R-1 for retardation layer]

[0269] The coating liquid R-1 for retardation layer was prepared by stirring and dissolving the following composition in a container maintained at 70°C.

[0270]

[0271] Mixture A of rod-like liquid crystal compounds

[0272] [Chemical formula 1]

[0273]

[0274] In the above mixture, the values are in mass%. And, R is a group bonded through an oxygen atom. Furthermore, the average molar extinction coefficient of the above rod-like liquid crystal compound at a wavelength of 300 to 400 nm is 140 / mol·cm.

[0275] Surfactant F1

[0276] [Chemical formula 2]

[0277]

[0278] Photoinitiator B

[0279] [Chemical formula 3]

[0280]

[0281] [Preparation of Coating Liquid R-2 for Phase Difference Layer]

[0282] The following composition was stirred and dissolved in a container maintained at 70 °C to prepare coating liquid R-2 for a phase difference layer having reverse wavelength dispersion.

[0283]

[0284] [Chemical Formula 4]

[0285]

[0286] [Chemical Formula 5]

[0287]

[0288] [Chemical Formula 6]

[0289]

[0290] [Chemical Formula 7]

[0291]

[0292] <Coating Liquid PA-1 for Light Interference Layer>

[0293] The following composition was stirred and dissolved in a container maintained at 60 °C to prepare coating liquid PA-1 for a light interference layer.

[0294]

[0295]

[0296] Photoinitiator C

[0297] [Chemical Formula 8]

[0298]

[0299] Photoacid Generator

[0300] [Chemical Formula 9]

[0301]

[0302] Hydrophilic Polymer

[0303] [Chemical Formula 10]

[0304]

[0305] Vertical Alignment Agent

[0306] [Chemical Formula 11]

[0307]

[0308] Visbreaking agent

[0309] [Chemical Formula 12]

[0310]

[0311] Material for interlayer photo-alignment film

[0312] [Chemical Formula 13]

[0313]

[0314] Stabilizer

[0315] [Chemical Formula 14]

[0316]

[0317] [Fabrication of retardation film 1]

[0318] As a pseudo support, a TAC (triacetyl cellulose) film with a thickness of 60 μm (manufactured by FUJIFILM Corporation, TG60) was prepared.

[0319] After coating the coating liquid PA-1 for the optical interference layer prepared above on the TAC film shown above using a wire bar coater, it was dried at 80 °C for 60 seconds. Then, in a low-oxygen atmosphere (100 ppm), at 78 °C, light from an ultraviolet LED lamp (wavelength 365 nm) with an irradiation dose of 300 mJ / cm 2 was irradiated to cure the liquid crystal compound, and at the same time, the cleavage groups of the material for the interlayer photo-alignment film were cleaved. Then, by heating at 115 °C for 25 seconds, the substituents containing fluorine atoms were removed. Thus, an optical interference layer with a positive C-plate function having a cinnamoyl group on the outermost surface and a film thickness of 90 nm was formed. The refractive index nI at a wavelength of 550 nm measured using an interference film thickness meter OPTM (manufactured by Otsuka Electronics Co., Ltd., analyzed by the least squares method) was 1.57. The Rth at a wavelength of 550 nm measured using Axoscan (manufactured by Axometrics, Inc.) was -9 nm.

[0320] Next, from the positive C-plate side, an illuminance of 7 mW / cm 2 and an irradiation dose of 7.9 mJ / cm 2polarized UV (wavelength 313 nm). The polarized UV with a wavelength of 313 nm is obtained by making the ultraviolet light emitted from a mercury lamp pass through a band-pass filter having a transmission band at a wavelength of 313 nm and a wire grid polarizer. After coating the phase difference layer preparation liquid R-1 prepared above on the light interference layer using a wire bar coater, it was dried at 110 °C for 72 seconds. Then, in a low oxygen atmosphere (100 ppm or less), at 100 °C, light from a metal halide lamp with an illuminance of 80 mW / cm 2 and an exposure dose of 500 mJ / cm 2 was irradiated for curing, thereby obtaining a phase difference film composed of a light interference layer and a phase difference layer. At this time, the coating thickness was adjusted so that the film thickness of the cured phase difference layer became 0.86 μm. The phase difference of the obtained phase difference film 1 at a wavelength of 550 nm was Re = 146 nm and Rth = 73 nm. In addition, AxoScan OPMF-1 (manufactured by Opto Science, Inc.) was used for the evaluation of the phase difference.

[0321] 〔Fabrication of Phase Difference Films 2 - 6, 8 - 16〕

[0322] For phase difference films 2 - 5, 8 - 16, the film thickness of the light interference layer was changed as shown in Table 1 below, and otherwise, they were fabricated by the same fabrication method as phase difference film 1. And for phase difference film 6, instead of providing a light interference layer, a phase difference layer was fabricated on a rubbed PET film (A4265 manufactured by TOYOBO CO., LTD., film thickness 100 μm) under the same conditions as phase difference film 1, thereby fabricating a phase difference film without a light interference layer.

[0323] 〔Fabrication of Phase Difference Film 7〕

[0324] Referring to the description of Example 3 in Japanese Patent Laid-Open No. 2012-155308, a coating liquid 1 for a photo-alignment film was prepared and coated on a 60-μm-thick TAC (triacetyl cellulose) film (TG60 manufactured by FUJIFILM Corporation) using a wire bar. By drying with warm air at 115 °C for 60 seconds, a light interference layer having a cinnamoyl group on the outermost surface and a film thickness of 90 nm and having the function of a photo-alignment film was formed. The refractive index nI at a wavelength of 550 nm measured using an interference film thickness meter OPTM (manufactured by Otsuka Electronics Co., Ltd., analyzed by the least squares method) was 1.55. The Rth at a wavelength of 550 nm measured using Axoscan (manufactured by Axometrics, Inc.) was 0 nm.

[0325] Next, from the light interference layer side, light with an illuminance of 7 mW / cm 2 and an exposure dose of 7.9 mJ / cm 2Polarized light UV (wavelength 313 nm). The polarized UV with a wavelength of 313 nm is obtained by transmitting the ultraviolet light emitted from a mercury lamp through a band-pass filter having a transmission band at a wavelength of 313 nm and a wire grid polarizer. After coating the phase difference layer preparation solution R-2 prepared above on the optical interference layer using a wire bar coater, it was dried at 110 °C for 72 seconds. Then, in a low oxygen atmosphere (100 ppm or less), at 100 °C, light from a metal halide lamp with an illuminance of 80 mW / cm 2 and an irradiation dose of 500 mJ / cm 2 was used for curing, thereby obtaining a phase difference film having an optical interference layer and a phase difference layer with reverse wavelength dispersion. At this time, the coating thickness was adjusted so that the film thickness of the cured phase difference layer became 2.5 μm. The phase difference of the obtained phase difference film 7 at a wavelength of 550 nm was Re = 146 nm and Rth = 73 nm. In addition, AxoScan OPMF-1 (manufactured by Opto Science, Inc.) was used for the evaluation of the phase difference.

[0326] [Fabrication of Phase Difference Film 17]

[0327] In the phase difference film 17, an optical alignment layer was formed as the optical interference layer by the following process, and the phase difference layer preparation solution was changed to R-2. Otherwise, it was fabricated by the same fabrication method as the phase difference film 1.

[0328] <Formation of Optical Alignment Layer>

[0329] The coating solution PA2 for forming an alignment layer described later was continuously coated on a 60-μm-thick TAC (triacetyl cellulose) film (manufactured by FUJIFILM Corporation, TG60) using a wire bar. The support with the formed coating film was dried with warm air at 140 °C for 120 seconds, and then, the coating film was irradiated with polarized ultraviolet light (10 mJ / cm 2 , using an ultra-high pressure mercury lamp), thereby forming an optical alignment layer. The film thickness was 90 nm. The refractive index nI at a wavelength of 550 nm measured using an interference film thickness meter OPTM (manufactured by Otsuka Electronics Co., Ltd., analyzed by the least squares method) was 1.55. The Rth at a wavelength of 550 nm measured using Axoscan (manufactured by Axometrics, Inc.) was 0 nm.

[0330]

[0331] Polymer M-PA-1

[0332] [Chemical Formula 15]

[0333]

[0334] Acid generator PAG-1

[0335] [Chemical formula 16]

[0336]

[0337] Acid generator CPI-110TF

[0338] [Chemical formula 17]

[0339]

[0340] [Production of retardation film 18]

[0341] The retardation of the retardation layer of the retardation film 18 was changed as shown in Table 1 below, and otherwise, it was produced by the same production method as that of the retardation film 17.

[0342] [Production of retardation film 19]

[0343] A hard coat with a refractive index of 1.56 and a film thickness of 90 nm was coated on the retardation layer of the retardation film 6, thereby forming an optical interference layer. The composition of the hard coat coating solution and the coating process are shown below.

[0344]

[0345] After coating the adjusted hard coat coating solution HC-1 on the retardation layer of the retardation film 6 shown above using a wire bar coater, it was dried at 80 °C for 60 seconds. Then, in a low oxygen atmosphere (100 ppm), ultraviolet light from an ultraviolet LED lamp (wavelength 365 nm) with an irradiation dose of 300 mJ / cm 2 was irradiated at 78 °C to cure the polymerizable compound. Thus, a retardation film 19 having an optical interference layer with a film thickness of 90 nm made of a hard coat material on the outermost surface was produced. The refractive index nI at a wavelength of 550 nm measured using an interference film thickness meter OPTM (manufactured by Otsuka Electronics Co., Ltd., analyzed by the least squares method) was 1.56. The Rth at a wavelength of 550 nm measured using Axoscan (manufactured by Axometrics, Inc.) was 0 nm.

[0346] The characteristics of the produced retardation films 1 to 19 are shown in Table 1 below. In addition, in Table 1, the retardation Re is the retardation Re of the retardation film, the refractive index is the refractive index of the optical interference layer, and the Rth is the Rth of the optical interference layer.

[0347] Table 1. Produced retardation films 1 to 19[Table 1]

[0348] Phase difference film Phase difference Re (nm) Thickness of the optical interference layer (nm) Refractive index Rth (nm) Phase difference film 1 146 90 1.57 -9 Phase difference film 2 146 80 1.57 -8 Phase difference film 3 146 100 1.57 -10 Phase difference film 4 146 270 1.57 -27 Phase difference film 5 146 180 1.57 -18 Phase difference film 6 146 None - - Phase difference film 7 146 90 1.55 0 Phase difference film 8 146 50 1.57 -5 Phase difference film 9 146 60 1.57 -6 Phase difference film 10 146 70 1.57 -7 Phase difference film 11 146 110 1.57 -11 Phase difference film 12 146 120 1.57 -12 Phase difference film 13 146 210 1.57 -21 Phase difference film 14 146 230 1.57 -23 Phase difference film 15 146 330 1.57 -33 Phase difference film 16 146 350 1.57 -35 Phase difference film 17 146 90 1.55 0 Phase difference film 18 292 90 1.55 0 Phase difference film 19 146 90 1.56 0

[0349] <Fabrication of linear polarizer>

[0350] A linear polarizer was fabricated according to the following steps.

[0351] (Fabrication of cellulose acylate film 1)

[0352] -Fabrication of core layer cellulose acylate concentrate-

[0353] The following composition was put into a mixing tank and stirred to dissolve each component, and a cellulose acetate solution used as the core layer cellulose acylate concentrate was prepared.

[0354]

[0355] Compound F

[0356] [Chemical formula 18]

[0357]

[0358] -Fabrication of outer layer cellulose acylate concentrate-

[0359] 10 parts by mass of the following matting agent solution was added to 90 parts by mass of the above-mentioned core layer cellulose acylate concentrate to prepare a cellulose acetate solution used as the outer layer cellulose acylate concentrate.

[0360]

[0361] -Fabrication of cellulose acylate film 1-

[0362] After filtering the above-mentioned core layer cellulose acylate concentrate and the above-mentioned outer layer cellulose acylate concentrate with a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm, the above-mentioned core layer cellulose acylate concentrate and the outer layer cellulose acylate concentrates on both sides thereof were simultaneously cast from a casting port onto a drum at 20 °C (a tape casting machine).

[0363] Next, it was peeled off in a state where the solvent content rate was about 20% by mass, and both ends in the width direction of the film were fixed with a tenter clamp, stretched transversely at a stretching ratio of 1.1 times, and dried.

[0364] After that, it was further dried by being conveyed between the rollers of a heat treatment device to produce an optical film with a thickness of 40 μm, which was used as cellulose acylate film 1. The in-plane retardation of the obtained cellulose acylate film 1 was 0 nm.

[0365] <Formation of photo-alignment layer PA1>

[0366] The alignment layer forming coating liquid S-PA-1 described below was continuously coated on the above-mentioned cellulose acylate film 1 using a wire bar. The support with the formed coating film was dried with warm air at 140 °C for 120 seconds. Then, polarized ultraviolet light irradiation (10 mJ / cm 2 , using an ultra-high pressure mercury lamp) was performed on the coating film, thereby forming a photo-alignment layer PA1. The film thickness was 0.3 μm.

[0367]

[0368] <Formation of the photoabsorptive anisotropic layer P1>

[0369] The coating liquid S-P-1 for forming the photoabsorptive anisotropic layer described below was continuously coated on the obtained alignment layer PA1 using a wire bar to form a coating layer P1. Then, the coating layer P1 was heated at 140 °C for 30 seconds and cooled to room temperature (23 °C). Next, it was heated at 90 °C for 60 seconds and cooled to room temperature again. After that, it was irradiated for 2 seconds under the irradiation condition of an LED lamp (center wavelength 365 nm) with an illuminance of 200 mW / cm 2 , thereby forming a photoabsorptive anisotropic layer P1 as a linear polarizer on the alignment layer PA1. The film thickness was 1.6 μm.

[0370]

[0371] Dichroic substance D-1

[0372] [Chemical formula 19]

[0373]

[0374] Dichroic substance D-2

[0375] [Chemical formula 20]

[0376]

[0377] Dichroic substance D-3

[0378] [Chemical formula 21]

[0379]

[0380] Polymeric liquid crystalline compound M-P-1

[0381] [Chemical formula 22]

[0382]

[0383] Low-molecular liquid crystalline compound M-1

[0384] [Chemical formula 23]

[0385]

[0386] Surfactant F-3

[0387] [Chemical Formula 24]

[0388]

[0389] [Fabrication of Stacked Optical Film 1]

[0390] As a wire reflection polarizer, a broadband dielectric multilayer film (trade name APF by 3M Company) was used. On one surface of the broadband dielectric multilayer film, a UV adhesive CHEMISEAL U2084B (manufactured by CHEMITECH CO., LTD., refractive index n 1.60 after curing) was coated using a wire bar coater until the thickness reached 2 μm. A phase difference film 1 was laminated thereon in such a way that the side opposite to the dummy support contacted the UV adhesive using a laminator. After purging with nitrogen in a nitrogen replacement chamber until the oxygen concentration became 100 ppm or less, ultraviolet rays from a high-pressure mercury lamp were irradiated from the dummy support side of the phase difference film 1 for curing. The illuminance was 25 mW / cm 2 , and the irradiation dose was 1000 mJ / cm 2 . After curing, the dummy support was peeled off. Also, on the surface of the broadband dielectric multilayer film opposite to the phase difference film 1, the light absorption anisotropic layer P1 was transferred in the same steps as above. The light absorption anisotropic layer P1 side of the fabricated film was laminated to a PMMA film with a thickness of 75 μm using the above UV adhesive CHEMISEAL U2084B. Thus, a stacked optical film 1 composed of a phase difference film 1, a wire reflection polarizer, and a linear polarizer was obtained.

[0391] For the phase difference films 2 to 17, 19, stacked optical films 2 to 17, 19 were also fabricated in the same steps.

[0392] [Fabrication of Stacked Optical Film 18]

[0393] As a linear reflection polarizer, a broadband dielectric multilayer film (trade name APF of 3M Company) was used. On one surface of the broadband dielectric multilayer film, a UV adhesive CHEMISEAL U2084B (manufactured by CHEMITECH CO., LTD., refractive index n 1.60 after curing) was coated using a wire bar coater until the thickness reached 2 μm. A phase difference film 18 was laminated thereon in such a manner that the side opposite to the pseudo support contacted the UV adhesive. At this time, the angle formed by the reflection axis of the broadband dielectric multilayer film and the slow axis of the phase difference film 18 was set to be 15 degrees. After purging with nitrogen in a nitrogen replacement chamber until the oxygen concentration became 100 ppm or less, ultraviolet rays from a high-pressure mercury lamp were irradiated from the pseudo support side of the phase difference film 18 for curing. The illuminance was 25 mW / cm 2 , and the irradiation dose was 1000 mJ / cm 2 . After curing, the pseudo support was peeled off. Next, a pressure-sensitive adhesive with a thickness of 5 μm (refractive index 1.49) was laminated on the surface of the phase difference film 18 on the side opposite to the linear reflection polarizer. A phase difference film 17 was laminated thereon in such a manner that the side opposite to the pseudo support contacted the pressure-sensitive adhesive. At this time, the angle formed by the reflection axis of the broadband dielectric multilayer film and the slow axis of the phase difference film 17 was set to be 75 degrees. After that, the pseudo support was peeled off. Also, on the surface of the broadband dielectric multilayer film on the side opposite to the phase difference film, the light absorption anisotropic layer P1 was transferred using the UV adhesive CHEMISEAL U2084B in the same steps as above. The light absorption anisotropic layer P1 side of the fabricated film was laminated to a PMMA film with a film thickness of 75 μm using the above UV adhesive CHEMISEAL U2084B. Thus, a laminated optical film 18 composed of a phase difference film 17 (Re(550) = 146 nm), a phase difference film 18 (Re(550) = 292 nm), a linear reflection polarizer, and a linear polarizer was obtained. A laminate in which the phase difference film 17 (Re(550) = 146 nm) and the phase difference film 18 (Re(550) = 292 nm) were overlapped at the above angles had the performance of a broadband λ / 4 plate, and thus a laminated optical film having a broadband λ / 4 plate was obtained.

[0394] [Forming a half mirror on the lens]

[0395] On the convex side of a lens (a convex meniscus lens LE1076-A (diameter 2 inches, focal length 100 mm) manufactured by Thorlabs and having an optical film 2 laminated on the concave side), aluminum evaporation was performed so that the reflectance became 40%, and a half mirror was formed.

[0396] [Molding method]

[0397] The laminated optical film 1 is placed in a molding device. The molding space in the molding device is composed of a mold box 1 and a mold box 2 separated by the laminated optical film 1. On the mold box 1 located on the lower side of the laminated optical film 1, a convex meniscus lens LE1076-A (diameter 2 inches, focal length 100 mm, curvature radius of the concave side 65 mm) manufactured by Thorlabs, Inc. with aluminum evaporation on the convex side is arranged with its concave surface facing upward as a mold. And, a transparent window is provided on the upper part of the mold box 2 located on the upper side of the laminated optical film 1, and an IR light source for heating the laminated optical film 1 is provided outside it. A circular patterned infrared reflection filter is arranged between the IR light source and the laminated optical film 1. This circular patterned infrared reflection filter is obtained by cutting out a circular shape with a diameter of 1 inch from a cholesteric liquid crystal layer that reflects infrared rays with a wavelength of 2.2 μm to 3.0 μm at a reflectivity of about 50%. At this time, it is arranged such that the center of the patterned infrared reflection filter is located at the center of the mold when viewed from directly above. Then, the inside of the mold box 1 and the inside of the mold box 2 are evacuated with a vacuum pump until they reach below 0.1 atmospheres respectively. Then, as a process of heating the laminated optical film 1, infrared rays are irradiated and heated until the center of the laminated optical film 1 reaches 99 °C and the ends reach 108 °C. The glass transition temperature Tg of the PMMA film used as a support is 105 °C, so the goal is to make it a state where the center is not easily stretched and the ends are easily stretched during molding. Then, as a process of pressing the laminated optical film 1 onto the mold and deforming it along the shape of the mold, gas is made to flow into the mold box 2 from a cylinder and pressurized to 300 kPa, and the laminated optical film 1 is pressed onto the mold. At this time, the laminated optical film 1 is optically bonded to the lens as a mold through a pressure-sensitive adhesive sheet. Finally, for the laminated optical film 1, by cutting and trimming the part that overflows from the lens as a mold, a composite lens 1 in which the laminated optical film 1 formed into a curved surface is attached to the lens is obtained.

[0398] The laminated optical films 2 to 19 are also formed into curved surfaces in the same steps.

[0399] 〔Evaluation of ghosting〕

[0400] [Fabrication of virtual reality display device]

[0401] The virtual reality display device adopting a reciprocating optical system, namely the virtual reality display device "Huawei VR Glass" manufactured by Huawei Technologies Co., Ltd., was disassembled, and all compound lenses were taken out. Instead, the compound lens 1 with the laminated optical film 1 attached was arranged such that the laminated optical film was located between the compound lens 1 and the eyes, thereby fabricating the virtual reality display device of Example 1. Additionally, at this time, the refractive index nA of the adhesive layer used when the laminated optical film 1 was set on the lens was 1.49 at a wavelength of 550 nm, and the average refractive index nL of the retardation layer was 1.63 at a wavelength of 550 nm. The square root of the product of these values ((nA × nL) 1 / 2 ) is 1.56, and the refractive index of the optical interference layer is 1.57. Therefore, it can be known that the refractive index of the optical interference layer is a preferable value for imparting an antireflection ability to the retardation film. In the fabricated virtual reality display device, a black-and-white checkerboard pattern was displayed on the image display panel, and the double image visibility was visually observed and evaluated in the following five stages.

[0402] Here, the refractive index of the adhesive layer and the average refractive index of the liquid crystal layer were measured using an interference film thickness meter OPTM (manufactured by Otsuka Electronics Co., Ltd., and analyzed using the least squares method).

[0403] <Evaluation of double image>

[0404] A: Completely invisible.

[0405] B: Slightly visible but not obvious.

[0406] C: Weak double image visible.

[0407] D: Slightly stronger double image visible.

[0408] E: Strong double image visible.

[0409] Furthermore, virtual reality display devices were fabricated in the same procedure using the laminated optical films 2 - 6, 8 - 16 for Examples 2 - 4, 6 - 10 and Comparative Examples 1 - 6. The refractive index nA of the adhesive layer used when the laminated optical films 2 - 6, 8 - 16 were set on the lens was 1.49 at a wavelength of 550 nm, and the average refractive index nL of the retardation layer was 1.63 at a wavelength of 550 nm. The square root of the product of these values ((nA × nL) 1 / 2 ) is 1.56, and the refractive index of the optical interference layer is 1.57. Therefore, it can be known that the refractive index of the optical interference layer is a preferable value for imparting an antireflection ability to the retardation film.

[0410] Furthermore, a virtual reality display device was fabricated in the same manner using the laminated optical film 7 for Example 5. The refractive index nA of the adhesive layer used when the laminated optical film 7 was disposed on the lens was 1.49 at a wavelength of 550 nm, and the average refractive index nL of the retardation layer was 1.58 at a wavelength of 550 nm. The square root of the product of these values ((nA × nL) 1 / 2 ) was 1.53, and the refractive index of the optical interference layer was 1.55. Therefore, it was found that the refractive index of the optical interference layer was a preferable value for imparting an antireflection ability to the retardation film.

[0411] Furthermore, a virtual reality display device was fabricated in the same manner using the laminated optical films 17 and 18 for Examples 11 and 12. The refractive index nA of the adhesive layer used when the laminated optical films 17 and 18 were disposed on the lens was 1.49 at a wavelength of 550 nm, and the average refractive index nL of the retardation layer was 1.58 at a wavelength of 550 nm. The square root of the product of these values ((nA × nL) 1 / 2 ) was 1.53, and the refractive index of the optical interference layer was 1.55. Therefore, it was found that the refractive index of the optical interference layer was a preferable value for imparting an antireflection ability to the retardation film.

[0412] Furthermore, a virtual reality display device was fabricated in the same manner using the laminated optical film 19 for Example 13. The refractive index nA of the adhesive layer used when the laminated optical film 19 was disposed on the lens was 1.49 at a wavelength of 550 nm, and the average refractive index nL of the retardation layer was 1.63 at a wavelength of 550 nm. The square root of the product of these values ((nA × nL) 1 / 2 ) was 1.56, and the refractive index of the optical interference layer was 1.56. Therefore, it was found that the refractive index of the optical interference layer was a preferable value for imparting an antireflection ability to the retardation film.

[0413] The types of retardation films and laminated optical films used in each of the examples and comparative examples are shown in Table 2. Also, the evaluation results of these double image visual recognition degrees are shown in Table 2.

[0414] As a result, in the virtual reality display devices of Comparative Examples 1 to 6, in the black display regions of the black-and-white grid pattern, the light in a part of the white display regions was visually recognized as strong double images. On the other hand, in the virtual reality display devices of Examples 1 to 13 using the retardation films provided with the optical interference layers satisfying the specified conditions, it was confirmed that the double images were improved. Furthermore, in Example 13 where the film thickness of the optical interference layer was 90 nm and the difference between (nA × nL) 1 / 2 and the refractive index of the optical interference layer was 0.00, it was confirmed that the double images were improved to such an extent that they were slightly visible but not obvious.

[0415] Table 2. Evaluation Results of Retardation Films and Double Images for Examples and Comparative Examples [Table 2]

[0416]

[0417] Symbol Explanation

[0418] 10 - 11 - retardation film, 21 - retardation layer, 22 - optical interference layer, 23 - adhesive layer, 100 - laminated optical film, 101 - adhesive layer, 102 - linear reflection polarizer, 103 - adhesive layer, 104 - linear polarizer, 300 - half - mirror, 400 - circular polarizer, 500 - image display panel, 600 - lens, 1000 - light rays forming virtual image, 2000 - light rays forming ghost image.

Claims

1. A retardation film formed by sequentially and adjacently disposing an optical interference layer and a retardation layer, wherein, The film thickness of the optical interference layer is 60 nm to 110 nm or 230 nm to 330 nm.

2. The retardation film according to claim 1, wherein the refractive index of the optical interference layer in the in-plane direction is 1.50 to 1.

70.

3. The retardation film according to claim 1, wherein the refractive index of the optical interference layer in the in-plane direction is 1.53 to 1.

59.

4. The retardation film according to claim 1, wherein the retardation film further has an adhesive layer, the retardation film is formed by arranging the adhesive layer, the optical interference layer, and the retardation layer adjacent to each other in sequence. When the refractive index of the adhesive layer is nA and the average refractive index of the retardation layer is nL, the in-plane refractive index nI of the optical interference layer is (nA × nL) 1 / 2 -0.03 ≤ nI ≤ (nA × nL) 1 / 2 +0.03 5. The retardation film according to any one of claims 1 to 4, wherein the optical interference layer is an optically oriented film.

6. The retardation film according to any one of claims 1 to 4, wherein the optical interference layer is a C-plate.

7. The retardation film according to claim 6, wherein a compound having a cinnamoyl group exists between the C-plate and the retardation layer.

8. The retardation film according to any one of claims 1 to 4, wherein the optical interference layer is a hard coat layer.

9. A laminated optical film having at least a retardation film and a wire reflection polarizer, wherein the retardation film is the retardation film according to any one of claims 1 to 4, and the wire reflection polarizer is disposed on the side of the retardation layer opposite to the optical interference layer.

10. The laminated optical film according to claim 9, wherein the laminated optical film further includes a linear polarizer.

11. The laminated optical film according to claim 10, wherein the linear polarizer at least includes a light absorption anisotropic layer containing a liquid crystal compound and a dichroic substance.

12. The laminated optical film according to claim 9, wherein the laminated optical film further includes a positive C-plate.

13. The laminated optical film according to claim 9, wherein the laminated optical film further includes an antireflection layer.

14. The laminated optical film according to claim 13, wherein the antireflection layer is a moth-eye film or an AR film.

15. The laminated optical film according to claim 9, wherein the laminated optical film includes a resin substrate having a peak temperature of the loss tangent tanδ of 170 °C or lower.

16. An optical article including the laminated optical film according to claim 9 and a lens.

17. A virtual reality display device including the optical article according to claim 16.

Images