Laminate and virtual reality display device

Abstract

The present invention provides a laminate having excellent heat resistance and excellent image sharpness when applied to a pancake lens type virtual reality display device, and a virtual reality display device. This laminate is provided with: an absorption-type polarizer which is a stretched resin film; a first protective layer disposed on one surface side of the absorption-type polarizer; and a second protective layer disposed on the other surface side of the absorption-type polarizer, in which the laminate has a curved surface portion, the absorption-type polarizer contains a resin having a cross-linked portion, the amount of a cross-linking agent derived from the cross-linked portion is 0.050 * 10-6 g / m3 or less, the thickness of each of the first protective layer and the second protective layer is 0.10-10 [mu] m, and the thickness of each of the first protective layer and the second protective layer is 0.10-10 [mu] m. The first protective layer and the second protective layer each contain a resin selected from the group consisting of an acrylic resin and a methacrylic resin.

Description

Technical Field

[0001] This invention relates to a laminate and a virtual reality display device. Background Technology

[0002] Virtual reality display devices are those that, by wearing dedicated headsets on the head and visually recognizing images displayed through lenses, provide a sense of presence as if entering a virtual world.

[0003] Virtual reality display devices typically have an image display panel and a Fresnel lens, but due to the large distance between the image display panel and the Fresnel lens, the headset becomes thicker, resulting in poor wearability.

[0004] Therefore, as described in Patent Document 1, a lens structure called a pancake lens is proposed, which has an image display panel, a reflective polarizer and a semi-reflective mirror, and the overall thickness of the headphones is reduced by making the light emitted from the image display panel reciprocate between the reflective polarizer and the semi-reflective mirror.

[0005] Previous technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 2020-519964 Summary of the Invention

[0008] The technical problem to be solved by the invention

[0009] In pancake lens-type virtual reality display devices, there is a need to further improve image clarity.

[0010] In the virtual reality display device described in Patent Document 1, an absorptive polarizer is used. This absorptive polarizer needs to be curved depending on the shape of the lens, etc. The inventors applied a conventional absorptive polarizer to a virtual reality display device and evaluated its characteristics, finding that image sharpness did not meet the latest higher requirements and needed further improvement.

[0011] Furthermore, high heat resistance is required in the absorption polarizers used. In addition, heat resistance refers to the suppression of changes in transmittance, an optical property, after the absorption polarizer has been left to stand in a high-temperature and high-humidity environment.

[0012] In view of the above, the objective of the present invention is to provide a laminate with excellent heat resistance and excellent image clarity when used in pancake lens type virtual reality display devices.

[0013] Another objective of this invention is to provide a virtual reality display device.

[0014] means for solving technical problems

[0015] The inventors have conducted in-depth research on the above-mentioned issues and discovered that the following structure can solve these issues.

[0016] (1) A laminated body having:

[0017] As an absorptive polarizer for stretching resin films;

[0018] A first protective layer is disposed on one surface side of the absorption polarizer; and

[0019] The second protective layer is disposed on the other surface side of the absorption polarizer, wherein...

[0020] The laminate has a curved surface.

[0021] Absorption polarizers contain resin with cross-linked portions.

[0022] The amount of crosslinking agent originating from the crosslinking section is 0.050 × 10⁻⁶. -6 g / m 3 the following,

[0023] The thickness of both the first and second protective layers is 0.10–10 μm.

[0024] Both the first and second protective layers contain resins selected from the group consisting of acrylic resins and methacrylic resins.

[0025] (2) A laminated body having:

[0026] As an absorptive polarizer for stretching resin films;

[0027] A first protective layer is disposed on one surface side of the absorption polarizer; and

[0028] The second protective layer is disposed on the other surface side of the absorption polarizer, wherein...

[0029] The laminate has a curved surface.

[0030] Absorption polarizers contain resins with boric acid crosslinking portions.

[0031] The amount of boric acid derived from the boric acid cross-linking section is 0.050 × 10⁻⁶. -6 g / m 3 the following,

[0032] The thickness of both the first and second protective layers is 0.10–10 μm.

[0033] Both the first and second protective layers contain resins selected from the group consisting of acrylic resins and methacrylic resins.

[0034] (3) The laminate according to (1) or (2), wherein,

[0035] Absorption polarizers contain iodine and polyvinyl alcohol resins.

[0036] (4) A virtual reality display device comprising, in sequence, an image display panel, an absorptive polarizer, a first phase difference layer, a half-reflective mirror, a second phase difference layer, a reflective polarizer, and a laminate as described in any one of (1) to (3).

[0037] (5) A virtual reality display device, comprising in sequence an image display panel, an absorptive polarizer, a phase difference layer, a half-reflective mirror, a reflective circular polarizer, and a stack of any one of (1) to (3).

[0038] Invention Effects

[0039] According to the present invention, a laminate with excellent heat resistance and excellent image clarity when used in pancake lens type virtual reality display devices can be provided.

[0040] According to the present invention, a virtual reality display device can be provided. Attached Figure Description

[0041] Figure 1 This is a top view of an example of the laminate of the present invention.

[0042] Figure 2 It is along Figure 1 A sectional view cut along line AA.

[0043] Figure 3 This is a diagram illustrating an example of a first embodiment of the virtual reality display device of the present invention.

[0044] Figure 4 This is a diagram illustrating an example of a second embodiment of the virtual reality display device of the present invention. Detailed Implementation

[0045] The present invention will now be described in detail.

[0046] The following description of the constituent elements is sometimes based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0047] In addition, in this specification, the numerical range indicated by “~” refers to the range included by taking the values ​​recorded before and after “~” as the lower limit and upper limit values.

[0048] In this specification, "absorption axis" refers to the polarization direction in which the in-plane absorbance is maximized when linearly polarized light is incident. "Reflection axis" refers to the polarization direction in which the in-plane reflectivity is maximized when linearly polarized light is incident. "Transmission axis" refers to the direction in-plane orthogonal to either the absorption or reflection axis. Furthermore, "slow axis" refers to the direction in-plane where the refractive index is maximized.

[0049] Furthermore, in this specification, Re(λ) and Rth(λ) represent the in-plane retardation and thickness retardation at wavelength λ, respectively. Unless otherwise specified, wavelength λ is set to 550 nm.

[0050] In this invention, Re(λ) and Rth(λ) are values ​​measured at wavelength λ using an AxoScan (manufactured by Axometrics). The following values ​​are calculated by inputting the average refractive index ((nx+ny+nz) / 3) and film thickness (d) into the AxoScan.

[0051] Slow axis direction (°)

[0052] Re(λ)=R0(λ)

[0053] Rth(λ)=((nx+ny) / 2-nz)×d

[0054] Additionally, R0(λ) is displayed as a value calculated by AxoScan, but refers to Re(λ).

[0055] Furthermore, in this specification, the refractive indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by ATAGO CO.,LTD.) and a sodium lamp (λ = 589 nm) as the light source. Moreover, when measuring wavelength dependence, a multi-wavelength Abbe refractometer DR-M2 (manufactured by ATAGO CO.,LTD.) can be used in combination with an interference filter for measurement.

[0056] Furthermore, values ​​from the polymer handbook (JOHN WILEY & SONS, INC) and various optical film product catalogs can be used. The following examples illustrate the average refractive index values ​​for major optical films: cellulose acylate (1.48), cyclic olefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0057] As a characteristic feature of the laminate of the present invention, the amount of crosslinking agent from the crosslinking portion (preferably the amount of boric acid from the boric acid crosslinking portion as described later) is below a specified value, and a protective layer containing a specified resin and having a thickness within a specified range is used.

[0058] The inventors investigated why conventionally stretched resin films used as absorbent polarizers failed to achieve the desired effects when applied to pancake lens-type virtual reality display devices. They discovered that when the absorbent polarizer was molded into a curved shape, its surface properties deteriorated, resulting in decreased image clarity. Therefore, through further research, the inventors found that reducing the amount of crosslinking agent originating from the crosslinking sections could prevent this surface property deterioration. Reducing the amount of crosslinking agent from the crosslinking sections means a lower crosslinking density. Consequently, it is speculated that the absorbent polarizer is easier to stretch when molded into a curved shape, and deformation during stretching can be suppressed, thereby preventing surface property deterioration.

[0059] Furthermore, in the laminate of the present invention, heat resistance is improved by using a protective layer containing a specified resin and having a thickness within a specified range. As a mechanism for heat resistance degradation, the inventors discovered that transmittance changes due to the diffusion of dichroic material contained in the absorptive polarizer to adjacent layers. Therefore, it is hypothesized that by configuring a protective layer containing a specified resin and having a thickness within a specified range as the layer adjacent to the absorptive polarizer, although the dichroic material diffuses into the protective layer, the concentration of the dichroic material tends to increase due to the thinness of the protective layer. As a result, the concentration gradient between the absorptive polarizer and the protective layer becomes smaller, suppressing the diffusion of the dichroic material and thus suppressing changes in transmittance.

[0060] <Layered Body>

[0061] The laminate of the present invention has an absorptive polarizer as a stretched resin film, a first protective layer disposed on one surface side of the absorptive polarizer, and a second protective layer disposed on the other surface side of the absorptive polarizer.

[0062] The laminate of the present invention has a curved surface.

[0063] The laminate of the present invention can be entirely curved, or a portion thereof can be curved. When a portion of the laminate is curved, the other portions can be planar.

[0064] The curved surface refers to the part with a curved shape.

[0065] The aforementioned surface shapes refer to shapes with a curvature exceeding 0, including surface shapes that are developable surfaces and three-dimensional surface shapes. A developable surface is a surface that can be planarly unfolded without stretching.

[0066] Regarding the shape of a developable surface, examples include surfaces equivalent to the circumference of a cylinder, elliptical cylinder, cone, and elliptical cone. These can be convex or concave surfaces. A three-dimensional surface refers to a surface that cannot be formed by deforming a plane; that is, a surface that is not a developable surface. Examples of three-dimensional surfaces include surfaces equivalent to spheres and ellipsoids of revolution, as well as surfaces with cross-sections that are parabolic or hyperbolic (e.g., paraboloids of revolution). These can be convex or concave surfaces.

[0067] The surface shape is preferably lens-shaped. Examples of lens-shaped surface shapes include spherical shapes and ellipsoidal surfaces, which can be either convex or concave.

[0068] The shape of the curved surface of the laminate is preferably spherical, ellipsoidal, or paraboloidal. That is, the curved surface is preferably a spherical part, an ellipsoidal part, or a paraboloidal part.

[0069] As described above, the shape of the curved surface of the laminate is preferably a body of revolution.

[0070] The radius of curvature of the curved surface of the laminate is not particularly limited, but it is preferably 20 to 80 mm, more preferably 30 to 80 mm.

[0071] exist Figure 1 An example of the laminate of the present invention is shown in the figure.

[0072] Figure 1 This is a top view of a stacked structure. Figure 2 It is along Figure 1 A sectional view cut along line AA. Line AA is the line passing through the center C of the stacked body 10, which is circular when viewed from above.

[0073] like Figure 1 and Figure 2 As shown, the laminate 10 includes an absorptive polarizer 12, a first protective layer 14 disposed on one surface of the absorptive polarizer 12, and a second protective layer 16 disposed on the other surface of the absorptive polarizer 12.

[0074] And, as Figure 1 and Figure 2 As shown, the laminate 10 has a curved shape. More specifically, as... Figure 2 As shown, the laminate 10 has a convex shape that curves towards the upper surface of the paper (convex shape). That is, the laminate 10 has a convex shape that protrudes towards one surface. Alternatively, the laminate 10 can also be described as having a concave shape that is recessed towards the other surface.

[0075] In the stack 10, the stack 10 as a whole corresponds to a curved surface.

[0076] like Figure 2 As shown, the laminate 10 has two opposing first surfaces 10A and second surfaces 10B. The first surface 10A is a convex curved surface facing the upper side of the paper surface, and the second surface 10B is a convex curved surface facing the upper side of the paper surface.

[0077] in addition, Figure 1 and Figure 2 The surface shape of the layer 10 shown is a paraboloid of revolution, but it can also be a spherical shape or an ellipsoid of revolution.

[0078] like Figure 1 As shown, when viewing the stacked body 10 from the normal direction of the cross plane of the center C (equivalent to the vertex of the convex part) of the stacked body 10 (viewing the stacked body 10 from above), the shape of the stacked body 10 is circular.

[0079] Furthermore, the center C of the aforementioned stacked body 10 is the intersection of the axis of the ellipsoidal shape and the stacked body 10, and when the stacked body 10 is assembled into the virtual reality display device described later, it is equivalent to the position where it intersects the normal of the center of the exit surface of the image display device.

[0080] When assembling the laminate 10 into the virtual reality display device described later, the laminate 10 is configured in a convex manner toward the image display panel side.

[0081] In addition, Figure 1 The invention describes the curved surface of the stacked body as circular when viewed from above (viewed from the axis of rotation of the stacked body), but the invention is not limited to this method. The curved surface of the stacked body when viewed from above can also be elliptical or other shapes.

[0082] The following is a detailed description of each component contained in the laminate.

[0083] <Absorption Polarizer>

[0084] The laminate of the present invention includes an absorptive polarizer (absorptive linear polarizer) as a stretched resin film.

[0085] Stretched resin film refers to a film obtained by stretching a resin film.

[0086] The polarization degree of the absorption polarizer is not particularly limited, but from the viewpoint of better performance in virtual reality display devices applicable to laminates, it is preferable to have a polarization degree of 99.0% or higher, more preferably 99.5% or higher, and even more preferably 99.9% or higher. The upper limit is not particularly limited, and 100% can be cited as an example.

[0087] The method for measuring the polarization degree of an absorption polarizer is as follows.

[0088] First, a portion of the absorptive polarizer (especially the central part) was cut into 2cm squares and attached to the FUJITAC TD80UL (manufactured by Fujifilm Corporation) using an adhesive sheet “NCF-D692(5)” manufactured by LINTEC Corporation. Then, the degree of polarization after visibility correction was calculated using an automatic polarization film measuring device VAP-7070 manufactured by JASCO Corporation.

[0089] Here, "polarization degree with visibility correction" refers to the average value obtained by measuring the transmittance in the wavelength region of 380-780nm when the light source, linear polarizer, and absorption polarizer are set up in sequence, the polarization degree of each wavelength is calculated by the following formula, and then multiplied by the visibility correction coefficient.

[0090] Degree of polarization P(%)={((Ty-Tx) / (Ty+Tx)) 1 / 2 ×100}

[0091] Tx: Transmittance when the incident polarized light emitted through the linear polarizer is configured in a manner that makes the transmission axis of the absorptive polarizer 1 orthogonal to the Nicol axis (with the incident polarized light set to 100%).

[0092] Ty: Transmittance when the incident polarized light emitted through the linear polarizer is arranged in a manner parallel to the transmission axis of the absorption polarizer 1 (with the incident polarized light set to 100%).

[0093] Absorption polarizers contain resin. The type of resin is not particularly limited, and well-known resins can be cited. Examples of resins include polyvinyl alcohol-based resins, (meth)acrylic resins, styrene-based resins, and cellulose-based resins.

[0094] Among them, polyvinyl alcohol-based resins are preferred, and examples include polyvinyl alcohol and its derivatives. Examples of polyvinyl alcohol derivatives include polyvinyl formal; polyvinyl acetal; and derivatives obtained by modifying polyvinyl alcohol, polyvinyl formal, and polyvinyl acetal with olefins such as ethylene and propylene, or unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid.

[0095] The average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10,000, more preferably 1,000 to 10,000.

[0096] Furthermore, the degree of saponification of the polyvinyl alcohol-based resin is preferably 80-100 mol%, more preferably 95-99.95 mol%.

[0097] In addition, the average degree of polymerization and degree of saponification can be determined in accordance with JIS K 6726.

[0098] The resin in an absorption polarizer has a cross-linked portion. The cross-linked portion is a bonding portion formed using a known cross-linking agent.

[0099] The type of crosslinking agent is not particularly limited, but when using the aforementioned polyvinyl alcohol-based resin as the resin, boric acid is preferred as the crosslinking agent. That is, the absorption polarizer can include a resin with boric acid crosslinking portions. The boric acid crosslinking portion refers to the crosslinking portion formed when boric acid is used as the crosslinking agent, which is formed by boric acid and the hydroxyl groups present in the resin.

[0100] The amount of crosslinking agent derived from the aforementioned crosslinking portion is 0.050 × 10⁻⁶. -6 g / m 3 From the viewpoint that the image clarity is superior when the laminate of the present invention is applied to a pancake lens type virtual reality display device, a resolution of 0.045 × 10⁻⁶ is preferred. -6 g / m 3 Below. Furthermore, from the viewpoint that laminates exhibit superior heat resistance, a heat resistance of 0.010 × 10⁻⁶ is preferred. -6 g / m 3 The above is preferred, 0.020×10 -6 g / m 3 The above is further optimized to 0.030×10 -6 g / m 3 above.

[0101] Furthermore, when the crosslinking part is a boric acid crosslinking part, the amount of the crosslinking agent is equivalent to the amount of boric acid.

[0102] The method for calculating the amount of crosslinking agent derived from the aforementioned crosslinking portion is not particularly limited, and known methods can be cited. For example, a method can be cited that involves cleaving bonds in the crosslinking portion to extract the crosslinking agent constituting the crosslinking portion and then measuring its content.

[0103] More specifically, when the cross-linking part is a boric acid cross-linking part, the amount of boric acid can be calculated through the following steps. First, an absorptive polarizer is cut into 1cm × 1cm pieces, 3cc of nitric acid is added, and then it is ashed using microwave at a maximum temperature of 230°C. After adding water to the obtained product to make the total amount 50g, the luminescence intensity of boron is measured using an ICP-OES (Optima 7300DV) manufactured by PerkinElmer.

[0104] Next, several aqueous solutions with known boric acid concentrations were prepared. Based on the ICP luminescence intensity data of boron measured using each aqueous solution, a calibration curve representing the relationship between boric acid content and luminescence intensity was prepared. Using this calibration curve, the boric acid content (g) was calculated based on the boron luminescence intensity data measured using an absorption polarizer. Then, the calculated boric acid content (g) was divided by the sample volume (1 cm × 1 cm × thickness) to calculate the boric acid content (g / m³). 3 ).

[0105] The resin content in the absorptive polarizer is not particularly limited, but it is preferably 50-99% by mass, more preferably 75-99% by mass, relative to the total mass of the absorptive polarizer.

[0106] Absorption polarizers preferably contain dichroic materials.

[0107] Dichroism refers to substances whose absorbance varies depending on the direction of light.

[0108] Dichroic materials are not particularly limited, and examples include visible light absorbing materials (dichroic pigments), luminescent materials (fluorescent materials, phosphorescent materials), ultraviolet light absorbing materials, infrared light absorbing materials, nonlinear optical materials, carbon nanotubes and inorganic materials (e.g., quantum rods), etc., and conventionally known dichroic materials (preferably dichroic pigments) can be used.

[0109] Among these, iodine is preferred as a dichroic substance. Iodine can exist in an ionic state.

[0110] Furthermore, in the case where an absorptive polarizer contains iodine and polyvinyl alcohol (PVA) resin, iodine can be used in the absorptive polarizer as I... - I2, I3 - I3 - -PVA complex and I5 - It exists in the form of PVA complexes, etc.

[0111] The content of dichroic material in an absorption polarizer is not particularly limited, but is preferably 0.1–1.5 g / m. 2 More preferably 0.1–1.0 g / m 2 .

[0112] In addition, the above g / m 2 This represents the area per unit area (m²) of an absorption polarizer. 2 The content (g) of dichroic substances in ).

[0113] Absorption polarizers may contain components other than the resin and dichroic material mentioned above. Examples of such components include plasticizers.

[0114] <First protective layer and second protective layer>

[0115] The laminate of the present invention includes a first protective layer and a second protective layer. The first and second protective layers are disposed on both sides of an absorptive polarizer to prevent the diffusion of dichroic substances. Both the first and second protective layers can function as adhesive layers.

[0116] Both the first and second protective layers are in contact with the absorption polarizer.

[0117] The thickness of both the first and second protective layers is 0.10 to 10 μm. From the viewpoint of superior heat resistance of the laminate, a thickness of 0.10 to 8.0 μm is preferred, and 0.10 to 6.0 μm is more preferred. Furthermore, when the thickness is 0.1 μm or more, the protective performance of the absorption polarizer is improved, and the adhesion is excellent when the first or second protective layer functions as an adhesive layer. Moreover, when the thickness is 10 μm or less, the heat resistance of the laminate is excellent.

[0118] The thickness mentioned above is the average thickness, which is calculated as follows.

[0119] First, expose the cross-section of the laminate and measure the thickness of the first protective layer (or the second protective layer) at more than 20 locations. Calculate the average thickness by arithmetically averaging these values ​​and use this value as the thickness of the first protective layer (or the second protective layer).

[0120] Both the first and second protective layers contain a resin selected from the group consisting of acrylic resins and methacrylic resins (hereinafter also referred to as "(meth)acrylic resin").

[0121] (Meth)acrylic resins refer to polymers whose main component is a monomer containing a (meth)acryloyl group. Here, the main component refers to the monomer with the highest content (by mass%) among the monomer components constituting the (meth)acrylic resin.

[0122] (Meth)acryloyl group refers to a group selected from the group consisting of acryloyl group and methacryloyl group.

[0123] The number of (meth)acryloyl groups in a monomer is not particularly limited, but 1 to 3 are preferred.

[0124] Examples of monomers having a (meth)acryloyl group include alkyl (meth)acrylates. Alkyl (meth)acrylates can be alkyl esters having 1 to 20 carbon atoms in the alkyl group, and the alkyl group can be straight-chain or branched. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate.

[0125] Alkyl methacrylates can be used alone or in combination of two or more.

[0126] In (meth)acrylic resin, the content of repeating units derived from (meth)acrylic alkyl esters is not particularly limited, but from the viewpoint of superior heat resistance of the laminate, 70 to 100% by mass is preferred, and 80 to 100% by mass is more preferred.

[0127] Other monomers besides (meth)acrylates include, for example, monomers having reactive groups (e.g., hydroxyl, carboxyl, amino, and epoxy groups) and monomers having aromatic rings.

[0128] Other monomers are preferably monomers having (meth)acryloyl groups.

[0129] The content of (meth)acrylic resin in the first protective layer is not particularly limited, but it is preferably 50 to 100% by mass, more preferably 75 to 99% by mass, relative to the total mass of the first protective layer.

[0130] The content of (meth)acrylic resin in the second protective layer is not particularly limited, but it is preferably 50 to 100% by mass, more preferably 75 to 99% by mass, relative to the total mass of the second protective layer.

[0131] <Method for manufacturing laminates>

[0132] The manufacturing method of the above-mentioned laminate is not particularly limited and can be any known method.

[0133] For example, the preferred method is as follows: after obtaining an absorptive polarizer as a stretched resin film, a first protective layer and a second protective layer are formed on both sides of the obtained absorptive polarizer, and then a curved surface is formed.

[0134] The steps of the above method are described in detail below.

[0135] There are no particular limitations on the methods for obtaining absorption polarizers; well-known methods can be cited.

[0136] When the absorptive polarizer contains iodine and polyvinyl alcohol-based resin and the crosslinking portion is a boric acid crosslinking portion, the following steps 1 to 6 are preferably performed. As described later, boric acid is used in steps 3 and 5, and boric acid is also used in step 6 as needed. By adjusting the amount of boric acid used in these steps, the amount of boric acid originating from the aforementioned boric acid crosslinking portion can be adjusted.

[0137] Step 1: A process of coating a composition containing a polyvinyl alcohol-based resin onto a substrate to form a resin layer, thereby obtaining a film before stretching.

[0138] Step 2: The process of stretching the pre-stretch film obtained in Step 1 (aerial assisted stretching process).

[0139] Step 3: The process of bringing the stretched film into contact with boric acid (insoluble treatment process).

[0140] Step 4: The process of dyeing the film obtained in Step 3 with iodine (dyeing treatment process).

[0141] Step 5: The step of contacting the film obtained in Step 4 with boric acid (crosslinking treatment step).

[0142] Step 6: The process of stretching the film obtained in Step 5 in an aqueous solution (aqueous stretching treatment process).

[0143] The steps for each process are described in detail below.

[0144] Step 1 is a process of coating a composition containing a polyvinyl alcohol resin onto a substrate to form a resin layer on the substrate, thereby obtaining a film before stretching.

[0145] The polyvinyl alcohol resin contained in the composition is as described above.

[0146] The above composition may contain a solvent. Examples of solvents include water and organic solvents.

[0147] From the viewpoint of improving the orientation of stretch-based polyvinyl alcohol molecules, the composition may contain halides. Examples of halides include iodides and sodium chloride. Examples of iodides include potassium iodide, sodium iodide, and lithium iodide.

[0148] The substrate used in step 1 is not particularly restricted, but thermoplastic resin substrate is preferred.

[0149] Examples of thermoplastic resin base materials include ester resins such as polyethylene terephthalate resins, cyclic olefin resins such as norbornene resins, olefin resins such as polypropylene resins, polyamide resins, polycarbonate resins, and their copolymers.

[0150] Examples of coating methods for the composition include roller coating, spin coating, wire rod coating, dip coating, mold coating, curtain coating, spray coating, and doctor blade coating (comma coating, etc.).

[0151] Step 2 is a process of stretching the pre-stretch film obtained in Step 1.

[0152] Examples of stretching methods in this process include fixed-end stretching (e.g., stretching using a tenter frame) and free-end stretching (e.g., uniaxial stretching by passing the film between rollers with different circumferential speeds).

[0153] The preferred stretch ratio is 2.0 to 3.5 times.

[0154] Stretching can be performed in one stage or in multiple stages.

[0155] The stretching temperature is preferably above the glass transition temperature (Tg) of the thermoplastic resin substrate, and more preferably above the glass transition temperature (Tg) + 10°C.

[0156] Step 3 is the process of bringing the stretched film into contact with boric acid.

[0157] The steps in this process are not particularly limited; for example, impregnating a film in a boric acid aqueous solution can be used.

[0158] The content of boric acid in the boric acid aqueous solution is preferably 1 to 10 parts by mass relative to 100 parts by mass of water.

[0159] The preferred temperature for the boric acid aqueous solution is 20–50°C.

[0160] Step 4 is the process of dyeing the film obtained in step 3 with iodine.

[0161] The steps of this process are not particularly limited. For example, methods such as immersing the film in a dyeing solution containing iodine, applying the dyeing solution to the film, and spraying the dyeing solution onto the film can be cited.

[0162] The iodine content in the staining solution is preferably 0.05 to 0.5 parts by weight relative to 100 parts by weight of water.

[0163] To improve the solubility of iodine in water, the staining solution preferably contains iodide. The iodide content in the staining solution is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, relative to 100 parts by weight of water.

[0164] The preferred temperature of the staining solution is 20–50°C.

[0165] The contact time between the film and iodine is preferably 5 seconds to 5 minutes, more preferably 30 to 90 seconds.

[0166] The ratio of iodine to iodide in the staining solution (iodine / iodide) is preferably 1 / 5 to 1 / 20, more preferably 1 / 5 to 1 / 10.

[0167] Step 5 is the process of bringing the thin film obtained in step 4 into contact with boric acid.

[0168] The steps in this process are not particularly limited; for example, impregnating a film in a boric acid aqueous solution can be used.

[0169] The content of boric acid in the boric acid aqueous solution is preferably 1 to 10 parts by mass relative to 100 parts by mass of water.

[0170] The preferred temperature for the boric acid aqueous solution is 20–50°C.

[0171] Step 6 is the process of stretching the film obtained in step 5 in an aqueous solution.

[0172] Boric acid aqueous solution is preferred as the aqueous solution used in this process.

[0173] The content of boric acid in the boric acid aqueous solution is preferably 1 to 10 parts by mass relative to 100 parts by mass of water, and more preferably 2.5 to 6 parts by mass.

[0174] Furthermore, the aqueous solution of boric acid may contain iodides.

[0175] The preferred temperature of the aqueous solution is 40–85°C, more preferably 60–75°C.

[0176] The preferred immersion time of the film in the aqueous solution is 15 seconds to 5 minutes.

[0177] Examples of stretching methods in this process include fixed-end stretching (e.g., stretching using a tenter frame) and free-end stretching (e.g., uniaxial stretching by passing the laminate between rollers with different circumferential speeds).

[0178] The stretching ratio is preferably 1.5 times or more, and more preferably 3 times or more.

[0179] The film obtained in step 6 can be further cleaned and dried.

[0180] The method of forming the first protective layer and the second protective layer on both sides of the obtained absorptive polarizer is not particularly limited. For example, a method can be given by coating the surface of the absorptive polarizer with a composition containing (meth)acrylic resin to form the first protective layer (or the second protective layer).

[0181] The (meth)acrylic resin contained in the above composition is as described above.

[0182] The above composition may contain a solvent. Examples of solvents include water and organic solvents.

[0183] Examples of coating methods for the composition include roller coating, spin coating, wire rod coating, dip coating, mold coating, curtain coating, spray coating, and doctor blade coating (comma coating, etc.).

[0184] Furthermore, as another method, one can cite another method of coating the above composition on a pseudo-support to form a first protective layer (or a second protective layer) and then transferring it onto an absorption polarizer.

[0185] The method for forming the curved surface is not particularly limited, and known methods can be used. For example, a method can be given for forming a laminate containing a first protective layer, an absorption polarizer, and a second protective layer using a molding die with a molding surface having a concave or convex shape.

[0186] Virtual Reality Display Devices

[0187] As a first embodiment of the virtual reality display device of the present invention, a virtual reality display device may be provided having an image display panel, an absorptive polarizer, a first phase difference layer, a half-reflective mirror, a second phase difference layer, a reflective polarizer, and the above-described stacked body in sequence.

[0188] Furthermore, as a second embodiment of the virtual reality display device of the present invention, a virtual reality display device comprising, in sequence, an image display panel, an absorptive polarizer, a phase difference layer, a semi-reflective mirror, a reflective circular polarizer, and the above-described stacked body can be cited.

[0189] Hereinafter, each embodiment will be described with reference to the accompanying drawings.

[0190] Figure 3 The virtual reality display device 100A shown has, in sequence, an image display panel 20, a λ / 4 phase difference layer 22, an absorptive polarizer 24, a λ / 4 phase difference layer 26, an anti-reflection layer 28, a semi-reflective mirror 30, a lens substrate 32, a λ / 4 phase difference layer 34, a reflective polarizer 36, and a laminate 38.

[0191] The laminate 38 includes the first protective layer, the absorption polarizer, and the second protective layer.

[0192] exist Figure 3 In the example shown, the λ / 4 phase difference layer 22, the absorptive polarizer 24, the λ / 4 phase difference layer 26, and the anti-reflection layer 28 are sequentially stacked on the display surface side of the image display panel 20.

[0193] The lens substrate 32 is arranged at a predetermined distance from the image display panel 20 (anti-reflective layer 28), with the side of the image display panel 20 being convex and the opposite side being concave.

[0194] The semi-reflective mirror 30 is stacked on the convex side of the lens substrate 32 and is bent along the curved shape of the convex surface of the lens substrate 32.

[0195] A λ / 4 phase difference layer 34, a reflective polarizer 36, and a stack 38 are sequentially stacked on the concave side of the lens substrate 32, and are respectively bent along the curved surface shape of the concave surface of the lens substrate 32.

[0196] In this virtual reality display device 100A, when unpolarized light (image light) is irradiated from the image display panel 20, it is converted into linearly polarized light in an unpolarized state through the λ / 4 phase difference layer 22, and then converted into circularly polarized light in the λ / 4 phase difference layer 26. That is, the transmission axis of the absorption polarizer 24 and the slow axis of the λ / 4 phase difference layer 26 are configured at 45°.

[0197] As an example, if we assume that the light is converted to left-hand circularly polarized light in the λ / 4 phase difference layer 26, then the left-hand circularly polarized light is incident on the half-reflector 30.

[0198] Approximately half of the left-handed circularly polarized light incident on the half-reflector 30 passes through the half-reflector 30 and the lens substrate 32, and is then incident on the λ / 4 phase retardation layer 34, where it is converted into linearly polarized light. This linearly polarized light then enters the reflective polarizer 36. The reflective polarizer 36 is configured to reflect this incident linearly polarized light, thus the linearly polarized light reflected by the reflective polarizer 36 is reflected towards the half-reflector 30. The linearly polarized light reflected by the reflective polarizer 36 is converted into left-handed circularly polarized light by the λ / 4 phase retardation layer 34. Approximately half of the left-handed circularly polarized light incident on the half-reflector 30 is reflected by the half-reflector 30. At this point, the left-handed circularly polarized light is converted into right-handed circularly polarized light.

[0199] Right-handed circularly polarized light, reflected by the semi-reflective mirror 30, passes through the lens substrate 32 and enters the λ / 4 phase retardation layer 34, where it is converted into linearly polarized light. This linearly polarized light then enters the reflective polarizer 36. The reflective polarizer 36 is configured to allow the incident linearly polarized light to pass through, thus the incident linearly polarized light passes through the reflective polarizer 36 and enters the laminate 38. An absorptive polarizer included in the laminate 38 is configured to allow the linearly polarized light to pass through, so the linearly polarized light also passes through the laminate 38 and exits towards the user U. Here, when viewed from the user U's side, the semi-reflective mirror 30 is concave. Therefore, due to the concave mirror effect of the semi-reflective mirror 30, the light is more focused and exits towards the visual recognition side shortly after being incident on the image display panel 20. Thus, the light appears to be emitted from a position farther than the image display panel 20. Therefore, for the user U who sees this light, it appears as if the light is incident from the back side of the image display panel 20 (the side opposite to the user U's side). Therefore, the image displayed on the image display panel 20 is perceived by the user U visually as a virtual image on the back side of the image display panel 20.

[0200] Furthermore, approximately half of the left-handed circularly polarized light reflected by the reflective circular polarizer 36 and incident on the semi-reflective mirror 30 passes through the semi-reflective mirror 30. This transmitted left-handed circularly polarized light passes through the anti-reflection layer 28 and is incident on the λ / 4 phase retardation layer 26, where it is converted into linearly polarized light. This linearly polarized light passes through the absorptive polarizer 24 and is incident on the λ / 4 phase retardation layer 22, where it is converted into circularly polarized light. This circularly polarized light is reflected by the surface of the image display panel 20 and is then incident again on the λ / 4 phase retardation layer 22. During reflection, the rotation direction of the circularly polarized light reverses, thus converting it into linearly polarized light in a direction orthogonal to the transmission axis of the absorptive polarizer 26 at the λ / 4 phase retardation layer 22. This linearly polarized light is absorbed by the absorptive polarizer 26.

[0201] Figure 4 The virtual reality display device 100B shown has, in sequence, an image display panel 20, a λ / 4 phase difference layer 22, an absorptive polarizer 24, a λ / 4 phase difference layer 26, an anti-reflection layer 28, a semi-reflective mirror 30, a lens substrate 32, a reflective circular polarizer 40, a λ / 4 phase difference layer 42, and a laminate 38.

[0202] The laminate 38 includes the first protective layer, the absorption polarizer, and the second protective layer.

[0203] Figure 4 The virtual reality display device 100B shown includes a reflective circular polarizer 40 and a λ / 4 phase difference layer 42 instead of Figure 3 The λ / 4 phase difference layer 34 and reflective polarizer 36 in the virtual reality display device 100A shown, apart from this, have the same... Figure 3It has the same structure as the virtual reality display device 100A shown.

[0204] exist Figure 4 In the virtual reality display device 100B shown, the same as described above Figure 3 Similarly, in the virtual reality display device 100A shown, left-handed circularly polarized light is incident on the semi-reflective mirror 30.

[0205] About half of the left-handed circularly polarized light incident on the half-reflecting mirror 30 passes through the half-reflecting mirror 30 and the lens substrate 32 before entering the reflective circular polarizer 40. At this time, the reflective circular polarizer 40 is a circular polarizer that reflects the left-handed circularly polarized light while allowing the right-handed circularly polarized light to pass through. Therefore, the incident left-handed circularly polarized light is reflected by the reflective circular polarizer 40 towards the half-reflecting mirror 30 side.

[0206] Approximately half of the left-handed circularly polarized light incident on the half-reflecting mirror 30 after being reflected by the reflective circular polarizer 40 is reflected by the half-reflecting mirror 30. At this point, the left-handed circularly polarized light is converted into right-handed circularly polarized light.

[0207] Right-hand circularly polarized light reflected by the semi-reflective mirror 30 passes through the lens substrate 32 and enters the reflective circular polarizer 40. However, the reflective circular polarizer 40 is a circular polarizer that allows right-hand circularly polarized light to pass through. Therefore, the incident right-hand circularly polarized light passes through the reflective circular polarizer 40 and enters the λ / 4 phase difference layer 42. The right-hand circularly polarized light incident on the λ / 4 phase difference layer 42 is converted into linearly polarized light and enters the laminate 38. The absorptive polarizer in the laminate 38 is configured to allow the linearly polarized light to pass through. Therefore, the linearly polarized light passes through the laminate 38 and exits towards the user U.

[0208] In the first and second embodiments described above, the method of using a λ / 4 phase difference layer as a phase difference layer was described, but the type of phase difference layer is not limited to this method.

[0209] The components, excluding the laminate, included in the virtual reality display device (first embodiment and second embodiment) described below will be described in detail.

[0210] (Image display panel)

[0211] Image display panels include, for example, well-known image display panels (display panels) such as organic electroluminescent (EL) display panels.

[0212] (λ / 4 phase difference layer)

[0213] A λ / 4 phase difference layer refers to a layer with λ / 4 functionality. Specifically, it refers to a layer that has the function of converting linearly polarized light of a specific wavelength (preferably visible light) into circularly polarized light (or converting circularly polarized light into linearly polarized light).

[0214] The in-plane delay of the λ / 4 phase retardation layer at a wavelength of 550 nm is not particularly limited, but it is preferably 120-150 nm, more preferably 125-150 nm, and even more preferably 135-150 nm.

[0215] In addition to the λ / 4 phase retardation layer, it is also preferable to have an in-plane retardation layer at a wavelength of 550 nm that is 3 / 4 or 5 / 4 of the wavelength of any light in the visible spectrum.

[0216] (Absorption polarizer)

[0217] An absorption polarizer is a component that absorbs polarized light (linearly polarized light) in a specific direction.

[0218] As an absorption polarizer, it is possible to use known absorption polarizers.

[0219] (Anti-reflective layer)

[0220] The type of anti-reflective layer is not particularly limited, but from the point of view of further reducing reflectivity, moth-eye film and AR (Anti Reflection) film are preferred.

[0221] (Partial reflective mirror)

[0222] A semi-reflective mirror is a component that allows approximately half of the incident light to pass through and reflects approximately half of the remaining light. Conventionally known semi-reflective mirrors can be used as semi-reflective mirrors.

[0223] The transmittance of the semi-reflective mirror is preferably 50±30%, more preferably 50±10%.

[0224] There are no particular restrictions on the types of semi-reflective mirrors; examples include reflective layers made of metal. Examples of metals include silver and aluminum.

[0225] The thickness of the semi-reflective mirror is preferably 1–20 nm, more preferably 2–10 nm, and even more preferably 3–6 nm.

[0226] (Lens substrate)

[0227] As a lens substrate, known lens substrates can be used, such as convex lenses and concave lenses.

[0228] Examples of convex lenses include biconvex lenses, plano-convex lenses, and convex meniscus lenses. Examples of concave lenses include biconcave lenses, plano-concave lenses, and concave meniscus lenses.

[0229] As a lens used in a virtual reality display device, from the viewpoint of expanding the viewing angle, a convex meniscus lens or a concave meniscus lens is preferred, and from the viewpoint of being able to further suppress chromatic aberration, a concave meniscus lens is more preferred.

[0230] Materials that are transparent to visible light, such as glass, crystals, and plastics, can be used as lens substrates.

[0231] (Reflective polarizer (Reflective linear polarizer))

[0232] A reflective polarizer is a polarizer that reflects one of two orthogonally polarized linearly polarized lights and allows the other linearly polarized light to pass through.

[0233] Examples of reflective polarizers include thin-film polarizers and wire-grid polarizers, which are formed by stretching dielectric multilayer films. Commercially available examples include the reflective polarizer (trade name APF) manufactured by 3M Company and the wire-grid polarizer (trade name WGF) manufactured by Asahi Kasei Corporation.

[0234] (Reflective circular polarizer)

[0235] A reflective circular polarizer is a polarizer that reflects one of the circularly polarized lights, either right-handed or left-handed, while allowing the other circularly polarized light to pass through.

[0236] Cholesterol-type liquid crystal layers can be cited as an example of reflective circular polarizers.

[0237] In addition to the components mentioned above, virtual reality display devices may also include other components.

[0238] Other components include, for example, a phase retardation layer such as a positive C-plate, a support structure, and an adhesive layer.

[0239] Example

[0240] The following examples provide a more detailed description of the features of the present invention. Furthermore, the materials, amounts, proportions, processing contents, and processing steps shown below can be appropriately modified as long as they do not depart from the spirit of the present invention. Moreover, structures other than those shown below can also be used, as long as they do not depart from the spirit of the present invention.

[0241] <Fabrication of Absorption Polarizer>

[0242] As the resin substrate, a strip-shaped amorphous polyethylene terephthalate (PET) copolymer film (thickness: 100 μm) with a water absorption rate of 0.75% and a glass transition temperature (Tg) of approximately 75 °C was used. One side of the resin substrate was subjected to corona treatment.

[0243] A PVA aqueous solution (coating solution) was prepared by adding 13 parts by mass of potassium iodide to 100 parts by mass of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEPHIMER Z410") in a 9:1 ratio.

[0244] A laminate was fabricated by coating the above-mentioned PVA aqueous solution onto the corona-treated surface of a resin substrate and drying it at 60°C to form a PVA-based resin layer with a thickness of 13 μm.

[0245] The obtained laminate was stretched uniaxially by 2.4 times along the longitudinal (length direction) free end between rollers with different circumferential speeds in an oven at 130°C (air-assisted stretching treatment).

[0246] Next, the laminate was immersed in an insoluble bath (an aqueous solution of boric acid containing 3.0% by mass of boric acid relative to the total mass of the aqueous boric acid solution) at a liquid temperature of 40°C for 30 seconds (insoluble treatment).

[0247] Next, the polarizer was immersed in a staining bath at 30°C (an iodine aqueous solution prepared by mixing iodine and potassium iodide in a mass ratio of 1:7 relative to 100 parts by mass of water) for 60 seconds while adjusting the concentration (staining treatment) to make the final polarizer's monomer transmittance (Ts) greater than 43.0%.

[0248] Next, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (an aqueous solution of boric acid prepared relative to 100 parts by mass of water, 3 parts by mass of potassium iodide, and 3.0 parts by mass of boric acid).

[0249] Then, while immersing the laminate in a boric acid aqueous solution (3.0% by mass boric acid and 5% by mass potassium iodide) at a temperature of 70°C, uniaxial stretching was performed between rollers with different circumferential speeds along the longitudinal direction (length direction) to make the total stretch ratio 5.5 times (water stretching treatment).

[0250] Then, the laminate was immersed in a cleaning bath at 20°C (an aqueous solution of 4 parts by mass of potassium iodide relative to 100 parts by mass of water) (cleaning treatment).

[0251] The resulting laminate was then dried in an oven maintained at 90°C while being brought into contact with SUS heated rollers with a surface temperature maintained at 75°C for approximately 2 seconds (drying shrinkage treatment). The width shrinkage rate of the laminate based on the drying shrinkage treatment was 5.2%.

[0252] In this manner, an absorption polarizer 1 with a thickness of 5 μm was formed on a resin substrate. At this time, the content of the dichroic material in the absorption polarizer was 0.5 g / m. 2 .

[0253] As shown in Table 1, the concentration (mass%) of boric acid in the insoluble bath during the insoluble treatment, the amount (mass%) of boric acid in the crosslinking bath during the crosslinking treatment, and the concentration (mass%) of boric acid in the aqueous solution of boric acid during the stretching treatment in water were changed. Otherwise, the absorptive polarizers 2 to 5 were manufactured according to the same steps as absorptive polarizer 1.

[0254] In addition, in Table 1, the "Boric Acid Concentration" column indicates the boric acid concentration (mass%) in the insoluble bath during the insoluble treatment and the boric acid concentration (mass%) in the aqueous boric acid solution during the stretching treatment in water, expressed as a value in "mass %". The amount of boric acid (parts by mass) in the crosslinking bath during the crosslinking treatment is expressed as a value in "parts by mass". For example, in the absorption polarizer 2, it indicates that the boric acid concentration (mass%) in the insoluble bath during the insoluble treatment and the boric acid concentration (mass%) in the aqueous boric acid solution during the stretching treatment in water are 2 parts by mass, and the amount of boric acid (parts by mass) in the crosslinking bath during the crosslinking treatment is 2 parts by mass.

[0255] [Table 1]

[0256] boric acid concentration Absorption polarizer 1 3 Absorption polarizer 2 2 Absorption polarizer 3 1 Absorption polarizer 4 0 Absorption polarizer 5 4

[0257] <Manufacturing of Polymer P1>

[0258] In a reaction vessel equipped with a stirrer, thermometer, reflux cooler, and nitrogen inlet, a mixture containing butyl acrylate (65 parts by mass), methyl acrylate (23 parts by mass), 2-phenoxyethyl acrylate (6 parts by mass), 2,2'-azobisisobutyronitrile (AIBN) (0.1 parts by mass), and ethyl acetate and toluene as solvents (solids concentration 50% by mass, toluene content in solvent 5% by mass) was stirred at 55°C under nitrogen atmosphere for 6 hours (polymerization reaction). This yielded a solution containing an acrylic polymer (polymer P1). Then, ethyl acetate was added to this solution to adjust the polymer concentration to 30% by mass. This yielded a polymer solution containing the acrylic polymer (polymer P1). The weight-average molecular weight of the acrylic polymer in the polymer solution was 1.15 million.

[0259] <Fabrication of components with protective layer>

[0260] The aforementioned polymer solution was applied to the corona-treated surface of a 38 μm thick transparent polyethylene terephthalate (PET) film, one side of which had undergone corona treatment (first side), and dried by heating at 130°C for 2 minutes, thereby forming an adhesive layer with a thickness of 5 μm. A 25 μm thick PET film (release film), one side of which had undergone release treatment based on a silicone-based release agent, was then bonded to this adhesive layer, thus creating a protective layer component 1 comprising the corona-treated PET film, a protective layer 1 as the adhesive layer, and a release film.

[0261] In addition, the thickness of the protective layer was set from 5 μm to 10 μm. Otherwise, the protective layer component 2 was manufactured according to the same steps as the manufacturing steps of the protective layer component 1 described above.

[0262] Furthermore, the thickness of the protective layer was set from 5 μm to 15 μm, and the protective layer component 3 was manufactured following the same steps as those for the above-mentioned component 1 with the protective layer.

[0263] <Creating Layered Bodies>

[0264] The PET film (peelable film) that has undergone a single-sided peeling treatment based on a silicone-based peeling agent is removed from the protective layer component 1, and the exposed protective layer 1 is attached to the absorptive polarizer 1, and the resin substrate adjacent to the absorptive polarizer 1 is peeled off.

[0265] The PET film (release film) on which a silicone-based release agent has been applied to one side is removed from the protective layer component 1, and the protective layer 1 is also applied to the side of the absorption polarizer 1 opposite to the side on which the protective layer 1 is applied, thereby creating a laminate 1 containing an absorption polarizer 1 with protective layers 1 on both sides.

[0266] In addition, a protective layer component 2 was used instead of a protective layer component 1. Otherwise, the laminate 2 was manufactured in the same manner as the laminate 1 described above.

[0267] Furthermore, an absorptive polarizer 2 was used instead of an absorptive polarizer 1. Otherwise, the laminate 3 was fabricated following the same steps as those for fabricating the laminate 1 described above.

[0268] Furthermore, an absorptive polarizer 3 was used instead of an absorptive polarizer 1. Otherwise, the laminate 4 was fabricated following the same steps as those for fabricating the laminate 1 described above.

[0269] Furthermore, an absorptive polarizer 4 was used instead of an absorptive polarizer 1. Otherwise, the laminate 5 was fabricated following the same steps as those for fabricating the laminate 1 described above.

[0270] Furthermore, the protective layer component 3 was used instead of the protective layer component 1, and the laminate 6 was manufactured in the same manner as the laminate 1 described above.

[0271] Furthermore, an absorptive polarizer 5 was used instead of an absorptive polarizer 1. Otherwise, the laminate 7 was fabricated following the same steps as those for fabricating the laminate 1 described above.

[0272] <Making of C-plate 1>

[0273] A positive C-plate 1 was fabricated by adjusting the film thickness, referring to the method described in paragraphs 0132 to 0134 of Japanese Patent Application Publication No. 2016-053709. The positive C-plate 1 has Re = 0.2 nm and Rth = -70 nm.

[0274] <Fabrication of Phase Difference Layer 1>

[0275] A phase retardation layer 1 with anti-wavelength dispersion was fabricated according to the method described in paragraphs 0151 to 0163 of Japanese Patent Application Publication No. 2020-084070. The phase retardation layer 1 has Re = 146 nm and Rth = 73 nm.

[0276] <Fabrication of Optical Components>

[0277] A corona-treated PET film was peeled off from both sides of the laminate 1 to obtain an absorptive polarizer 1 with protective layers 1 on both sides. Next, an optical component 1 was fabricated by sequentially bonding a retardation layer 1, a reflective polarizer, an absorptive polarizer 1 with protective layers 1 on both sides, and the retardation layer 1. Furthermore, the retardation layer 1 and the reflective polarizer were bonded using an adhesive sheet “NCF-D692(5)” manufactured by LINTEC Corporation.

[0278] In addition, a laminate 2 was used instead of a laminate 1, and the optical component 2 was manufactured in the same manner as the optical component 1 described above.

[0279] Furthermore, a laminate 3 was used instead of a laminate 1, and the optical component 3 was manufactured in the same manner as the optical component 1 described above.

[0280] Furthermore, a laminate 4 was used instead of a laminate 1, and the optical component 4 was manufactured in the same manner as the optical component 1 described above.

[0281] Furthermore, a laminate 5 was used instead of a laminate 1, and the optical component 5 was manufactured in the same manner as the optical component 1 described above.

[0282] Furthermore, a laminate 6 was used instead of a laminate 1, and the optical component 6 was manufactured in accordance with the same steps as those for the optical component 1 described above.

[0283] Furthermore, a laminate 7 was used instead of a laminate 1, and the optical component 7 was manufactured in the same manner as the optical component 1 described above.

[0284] <The Production of Virtual Reality Display Devices>

[0285] The image display panel of Facebook's Oculus Quest virtual reality display device was removed after disassembly. This image display panel is an organic EL display panel, and the λ / 4 phasor layer and absorptive polarizer attached to the surface were peeled off.

[0286] Next, using an adhesive sheet "NCF-D692(5)" manufactured by LINTEC Corporation, the fabricated retardation layer 1, the absorptive polarizer 5, the retardation layer 1, and the positive C-plate 1 were sequentially bonded to the surface of the aforementioned image display panel. Furthermore, during the bonding of the retardation layer 1, the absorptive polarizer 5, and the positive C-plate 1, their respective pseudo-supports were peeled off and removed. The image display panel 1 obtained in this manner emits right-handed circularly polarized light.

[0287] Next, a concave meniscus lens (made of optical glass) with a diameter of 50 mm, a curvature radius of 65 mm on the curved surface, and a single side coated with a semi-reflective mirror was prepared, and the optical component 1 was formed on the curved surface of the concave meniscus lens. That is, a laminate 1 with a curved surface was formed. In addition, regarding the forming of the laminate 1 (optical component 1) on the curved surface of the concave meniscus lens, an adhesive sheet "NCF-D692(5)" manufactured by Lintec Corporation was attached to the bonding surface of the phase difference layer 1 in the optical component 1, and vacuum forming was performed by the method described in Japanese Patent Application Publication No. 2012-116094 with the release film of the adhesive sheet removed. The forming temperature was set to 120°C. In this way, a concave meniscus lens 1 with the optical component 1 attached to the curved surface and coated with a semi-reflective mirror was produced. In addition, the optical component 1 was attached to the concave meniscus lens 1 in such a way that the reflective polarizer was positioned closer to the semi-reflective mirror coating side than the absorptive polarizer. At this time, the concave meniscus lens 1 is configured such that the concave side is located on the visual recognition side, and the distance of the concave meniscus lens is adjusted and set to appropriately display virtual reality display images, thereby creating a virtual reality display device 1.

[0288] In addition, optical component 2 was used instead of optical component 1. Otherwise, virtual reality display device 2 was manufactured in the same manner as virtual reality display device 1 described above.

[0289] Furthermore, optical component 3 was used instead of optical component 1, and the virtual reality display device 3 was manufactured in accordance with the same steps as those for manufacturing the virtual reality display device 1 described above.

[0290] Furthermore, optical component 4 was used instead of optical component 1, and the virtual reality display device 4 was manufactured in accordance with the same steps as those for manufacturing the virtual reality display device 1 described above.

[0291] Furthermore, optical component 5 was used instead of optical component 1, and the virtual reality display device 5 was manufactured in accordance with the same steps as those for manufacturing the virtual reality display device 1 described above.

[0292] Furthermore, optical component 6 was used instead of optical component 1, and the virtual reality display device 6 was manufactured in accordance with the same steps as those for manufacturing the virtual reality display device 1 described above.

[0293] Furthermore, optical component 7 was used instead of optical component 1, and the virtual reality display device 7 was manufactured in accordance with the same steps as those for manufacturing the virtual reality display device 1 described above.

[0294] <Evaluation>

[0295] (Quantitative evaluation of boric acid)

[0296] The absorptive polarizer 1 was cut into 1cm × 1cm pieces, and after adding 3cc of nitric acid, it was ashed using microwave at a maximum temperature of 230°C. Water was added to the obtained product to make a total volume of 50g, and the luminescence intensity of boron was measured using an ICP-OES instrument (Optima 7300DV) manufactured by PerkinElmer.

[0297] Next, several aqueous solutions with known boric acid concentrations were prepared, and a calibration curve representing the relationship between boric acid content and luminescence intensity was prepared based on the ICP luminescence intensity data of boron measured using each aqueous solution. Using this calibration curve, the boric acid content (g) was calculated based on the boron luminescence intensity data measured using the sample with absorption polarizer 1. Then, the calculated boric acid content (g) was divided by the sample volume (1cm × 1cm × thickness) to calculate the boric acid content (g / m³). 3 ).

[0298] For absorption polarizers 2 to 5, the amount of boric acid was calculated using the same procedure.

[0299] (Polarization degree evaluation)

[0300] Following the same steps as described in the above-mentioned <Production of Virtual Reality Display Device>, the absorptive polarizer 1 was surface-formed. Regarding the polarization performance of the obtained surface-formed absorptive polarizer 1, a 2cm square section was cut from the center of the absorptive polarizer 1. After attaching it to a FUJITAC TD80UL (manufactured by Fujifilm Corporation) using an adhesive sheet "NCF-D692(5)" manufactured by LINTEC Corporation, the degree of polarization after visibility correction was calculated using an automatic polarization film measuring device VAP-7070 manufactured by JASCO Corporation, and the results were evaluated. The results are shown in Table 2 below.

[0301] Here, "polarization degree with visibility correction" refers to the average value obtained by measuring the transmittance in the wavelength region of 380 to 780 nm incident from the FUJITAC TD80UL side by sequentially setting up the light source, linear polarizer, and absorption polarizer 1, calculating the polarization degree of each wavelength using the following formula, and multiplying it by the visibility correction coefficient.

[0302] Degree of polarization P(%)={((Ty-Tx) / (Ty+Tx)) 1 / 2 ×100}

[0303] Tx: Transmittance when the incident polarized light emitted through the linear polarizer is configured in a manner that makes the transmission axis of the absorptive polarizer 1 orthogonal to the Nicol axis (with the incident polarized light set to 100%).

[0304] Ty: Transmittance when the incident polarized light emitted through the linear polarizer is arranged in a manner parallel to the transmission axis of the absorption polarizer 1 (with the incident polarized light set to 100%).

[0305] In addition, the degree of polarization for absorption polarizers 2 to 5 was calculated using the same procedure.

[0306] (Heat resistance test)

[0307] Following the same steps as described in the above-mentioned <Fabrication of Virtual Reality Display Device>, laminate 1 was surface-formed. For the surface-formed laminate 1, a 2cm x 2cm section was cut from the center, a PET film was peeled off from one side, and it was attached to a FUJITAC TD80UL (manufactured by Fujifilm Corporation). The remaining PET film was then peeled off, thus preparing a sample attached to the FUJITAC TD80UL. The single-layer transmittance of the prepared sample was measured using the following method. Then, the sample was placed in a constant temperature and humidity chamber and stored at 85°C and dry for 500 hours to conduct a heat resistance test. The single-layer transmittance of the sample after the heat resistance test was measured using the following method. Based on the single-layer transmittance values ​​before and after the heat resistance test measured using the above method, the transmittance change ΔT (single-layer transmittance after heat resistance test - single-layer transmittance before heat resistance test) was calculated. The closer the transmittance change ΔT is to 0, the better the heat resistance. If the answer is A to C, then it is a level that is practically feasible.

[0308] The heat resistance of laminates 2–7 was evaluated using the same procedure.

[0309] A: Transmittance change ΔT is greater than 0.0% and less than 1.0%.

[0310] B: Transmittance change ΔT is greater than 1.0% and less than 3.0%.

[0311] C: Transmittance change ΔT is greater than 3.0% and less than 5.0%.

[0312] D: Transmittance change ΔT is 5.0% or more.

[0313] -Plate transmittance-

[0314] Transmittance refers to the average value obtained by multiplying the transmittance measured using the JASCO Corporation VAP-7070 automatic polarizing film measuring device at wavelengths of 380 to 780 nm by a visibility correction factor. The transmittance of a single panel is defined as (Tx+Ty) / 2 as shown in the following formula.

[0315] Tx: Transmittance when the incident polarized light and the transmission axis of the absorptive polarizer in the sample are orthogonal to each other (with the incident polarized light set to 100%).

[0316] Ty: Transmittance when the incident polarized light is arranged parallel to the transmission axis of the absorptive polarizer in the sample (with the incident polarized light set to 100%).

[0317] <Evaluation of image sharpness>

[0318] In the manufactured virtual reality display devices 1 to 7, a black and white checkered pattern was displayed on an image display device, and the degree of image sharpness was visually evaluated in three stages. Furthermore, if the image sharpness is poor, part or all of the checkered pattern appears distorted. Option A or B is preferred.

[0319] A: The deformation of the grid pattern is almost undetectable.

[0320] B; The distortion of the grid pattern can be slightly identified, but it is not a major issue.

[0321] C; The deformation of the grid pattern can be clearly identified.

[0322] [Table 2]

[0323]

[0324] As shown in Table 2, the laminate of the present invention exhibits the desired effect.

[0325] Based on the comparison of Examples 1 and 2, it was confirmed that the heat resistance was better when the thickness of the protective layer was less than 8.0 μm.

[0326] Based on the comparison of Examples 1 and 3-4, it was confirmed that a crosslinking dosage of 0.020 × 10⁻⁶ was optimal. -6 g / m 3 Under the above conditions, the heat resistance is even better, at 0.030×10 -6 g / m 3 Under the above conditions, the heat resistance is further improved.

[0327] Symbol Explanation

[0328] 10, 38 - Laminated body; 12, 26 - Absorption polarizer; 14 - First protective layer; 16 - Second protective layer; 20 - Image display panel; 22, 26, 34, 42 - λ / 4 phase difference layer; 28 - Anti-reflection layer; 30 - Semi-reflective mirror; 32 - Lens substrate; 36 - Reflective polarizer; 38 - Laminated body; 40 - Reflective circular polarizer.

Claims

1. A laminated body having: As an absorptive polarizer for stretching resin films; A first protective layer is disposed on one surface side of the absorption polarizer; and A second protective layer is disposed on the other surface side of the absorption polarizer, wherein... The laminate has a curved surface. The absorptive polarizer comprises a resin having cross-linked portions. The amount of crosslinking agent originating from the crosslinking portion is 0.050 × 10⁻⁶. -6 g / m 3 the following, The thickness of both the first protective layer and the second protective layer is 0.10–10 μm. Both the first protective layer and the second protective layer comprise a resin selected from the group consisting of acrylic resins and methacrylic resins.

2. A laminated body having: As an absorptive polarizer for stretching resin films; A first protective layer is disposed on one surface side of the absorption polarizer; and A second protective layer is disposed on the other surface side of the absorption polarizer, wherein... The laminate has a curved surface. The absorptive polarizer comprises a resin having a boric acid crosslinking portion. The amount of boric acid originating from the boric acid crosslinking portion is 0.050 × 10⁻⁶. -6 g / m 3 the following, The thickness of both the first protective layer and the second protective layer is 0.10–10 μm. Both the first protective layer and the second protective layer comprise a resin selected from the group consisting of acrylic resins and methacrylic resins.

3. The laminate according to claim 1 or 2, wherein, The absorptive polarizer contains iodine and polyvinyl alcohol resin.

4. A virtual reality display device, comprising, in sequence, an image display panel, an absorptive polarizer, a first phase difference layer, a half-reflective mirror, a second phase difference layer, a reflective polarizer, and the laminate as described in claim 1 or 2.

5. A virtual reality display device, comprising, in sequence, an image display panel, an absorptive polarizer, a phase difference layer, a semi-reflective mirror, a reflective circular polarizer, and the laminate as described in claim 1 or 2.

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