Wire grid polarization element, method for producing wire grid polarization element, image projection display device, and vehicle

Abstract

In the present invention, a wire grid polarization element 1 comprises: a substrate 10 made of an inorganic material; a grid structure 20 in which a plurality of projecting strip sections 22 are integrally formed with a base part 21 which is made of an organic material and provided on the substrate 10; and a functional film 30 which is made of a metal material and covers a part of a projecting strip section 22. The organic material is a cured product of a photocurable acrylic resin for imprinting, which contains a photopolymerizable component. The photopolymerizable component contains a resin (A) and a resin (B). The resin (A) is a monofunctional acrylate monomer having a phenyl group and / or a benzyl group. The resin (B) is a difunctional compound. The content of the resin (A) is 20-42 mass% relative to the overall photopolymerizable component. The content of the resin (B) is 43-66 mass% relative to the overall photopolymerizable component.

Description

Wire grid polarizer, method for manufacturing wire grid polarizer, projection display device and vehicle

[0001] The present invention relates to a wire grid polarizer having good polarization characteristics, excellent transmittance for obliquely incident light and light incident at a wide range of angles of incidence, without compromising heat dissipation or manufacturing costs, a method for manufacturing a wire grid polarizer, a projection display device having excellent polarization characteristics and heat resistance, and a vehicle equipped with the projection display device. This application claims the benefit of priority based on Japanese Patent Application No. 2023-216487 filed on December 22, 2023, and Japanese Patent Application No. 2024-225993 filed on December 23, 2024, the contents of which are incorporated herein by reference.

[0002] As one type of projection display device, many vehicular head-up display devices have been developed in recent years, which display images on a semi-transparent plate (hereinafter collectively referred to as a "display surface") such as a windshield or a combiner of a vehicle. A vehicular head-up display device is an image display device that is disposed, for example, on the dashboard of a vehicle and projects image light onto the windshield to display driving information as a virtual image. Because the driver can simultaneously view the virtual image and the scenery through the windshield, this has the advantage of reducing the driver's line of sight movement compared to conventional display devices such as liquid crystal displays that are installed outside the range of the windshield.

[0003] However, because the above-mentioned head-up display device projects a display image from below toward the windshield (upward), sunlight can enter the display element in a direction opposite to the direction of projection of the display image. Head-up display devices often include a reflector for reflecting and enlarging the display image to meet the demands for compactness and to enlarge the display image. In such cases, sunlight entering the head-up display device is concentrated near the display element, potentially causing heat degradation or failure of the display element.

[0004] Therefore, a technology has been developed to provide a reflective polarizing element in a head-up display device in order to prevent sunlight from entering the display element. For example, Patent Document 1 discloses a head-up display device in which a reflective polarizing element (wire grid polarizer) is provided between a reflector and a display element.

[0005] Examples of polarizing elements that can be used in head-up display devices include polarizing elements made of birefringent resin, wire-grid polarizing elements in which multiple conductors (thin metal wires) extend parallel to a transparent substrate, and polarizing elements made of cholesteric phase liquid crystal. Among these, wire-grid polarizing elements, which have excellent polarization characteristics, are widely used. Wire-grid polarizing elements form a wire grid in which conductor wires made of metal or other materials are arranged in a lattice pattern at a specific pitch. By setting the arrangement pitch of the wire grid to a pitch smaller (e.g., half or less) than the wavelength of incident light (e.g., visible light), it is possible to reflect most of the light with an electric field vector component oscillating parallel to the conductor wires and transmit most of the light with an electric field vector component perpendicular to the conductor wires. As a result, wire-grid polarizing elements can be used as polarizing elements that generate single-polarized light and can reflect and reuse light that is not transmitted, making them desirable from the perspective of efficient light utilization. The term "polarizing element" as used here also includes polarizing elements that can be used as polarizing beam splitters that separate incident light into S-polarized and P-polarized light.

[0006] As an example of such a wire-grid polarizing element, Patent Document 2 discloses a wire-grid polarizing plate including a resin substrate having grid-shaped convex portions, a dielectric layer provided so as to cover the grid-shaped convex portions of the resin substrate, and metal wires provided on the dielectric layer.

[0007] Patent Document 3 discloses a wire grid polarizer having a substrate made of a resin or the like and having a concave-convex structure extending in a specific direction on its surface, and a conductor provided so as to be unevenly distributed on one side surface of the convex portions of the concave-convex structure. In this wire grid polarizer, the pitch, which is the distance between two adjacent convex portions, and the height of the convex portions are adjusted in a cross-sectional view perpendicular to the extending direction of the concave-convex structure.

[0008] Furthermore, Patent Document 4 discloses a projection-type image display device that uses a reflective liquid crystal display element and a reflective wire-grid polarizer as a polarizing beam splitter. In the projection-type image display device using the reflective liquid crystal display element described in Patent Document 4, the reflective wire-grid polarizer is arranged at an angle of approximately 45° to the optical axis of light emitted from a light source. The light emitted from the light source is separated into a first polarized light (reflected light) and a second polarized light (transmitted light) by entering the reflective wire-grid polarizer at an angle of approximately 45° to the reflective liquid crystal display element. The first polarized light reflected by the reflective wire-grid polarizer is then modulated and reflected by the reflective liquid crystal display element to become the second polarized light, and the second polarized light is transmitted through the reflective wire-grid polarizer to be projected and displayed.

[0009] Furthermore, Patent Document 5 discloses a vehicle headlamp that uses a reflective wire-grid polarizer as a polarized beam splitter. In the vehicle headlamp described in Patent Document 5, the reflective wire-grid polarizer is also disposed at an angle of approximately 45° to the optical axis of light emitted from a light source. When light emitted from the light source enters the reflective wire grid at an angle of incidence of approximately 45°, the light is separated into a first polarized light (reflected light) and a second polarized light (transmitted light).

[0010] When a reflective wire-grid polarizer is positioned at an angle of approximately 45° to the light emitted from a light source, such as in the projection-type image display device described in Patent Document 4 and the vehicle headlamp described in Patent Document 5, the incident light does not only enter the reflective wire-grid polarizer at a single incident angle of 45°, but also at incident angles in the range of approximately 45°±15°.

[0011] Furthermore, Patent Document 6 discloses a wire grid polarization beam splitter in which a plurality of grids made entirely of silver or aluminum are formed on a substrate so as to protrude therefrom.

[0012] JP 2018-72507 A JP 2008-83657 A JP 2017-173832 A JP 2004-184889 A JP 2019-50134 A JP 2003-508813 A JP 2018-125559 A Japanese Patent No. 4824068

[0013] Generally, the temperature environment required for devices used in vehicles is −40 to 105°C. However, when considering use in high-temperature environments, such as a head-up display mounted on the dashboard of a vehicle in summer, high heat resistance and heat dissipation are required. In this regard, the wire grid polarizers described in Patent Documents 1 to 3 are required to have further improvements in heat resistance and heat dissipation. Furthermore, in order to brightly illuminate the road at night using the vehicle headlamp described in Patent Document 5, it is essential that the vehicle headlamp be made highly bright. For this reason, the wire grid polarizer described in Patent Document 5 is required to have high heat resistance and heat dissipation against heat from the light source.

[0014] Furthermore, conventional wire grid polarizers have problems such as high manufacturing costs and being unsuitable for mass production, because the uneven surface shape is generally formed using photolithography or etching techniques.

[0015] The inventors of the present invention conducted extensive research to solve the above-mentioned problems and discovered the following. First, the substrate of a wire-grid polarizer is formed from a transparent inorganic material, and the grid structure provided on the substrate is integrally formed from a transparent organic material. This allows the wire-grid polarizer to have a hybrid structure made of organic and inorganic materials. As a result, the heat dissipation properties of the wire-grid polarizer can be significantly improved.

[0016] Furthermore, the grid structure used has a base portion provided along the surface of the substrate and a plurality of ridge portions protruding from the base portion, which are integrally formed. This allows the grid structure to be formed by a technique such as nanoimprinting, which reduces the manufacturing cost of the grid structure compared to when photolithography or etching is used, and also enables mass production.

[0017] Furthermore, when a functional film such as a reflective film that reflects light or an absorbing film that absorbs light is provided on the convex rib portions of the grid structure, the coverage area and coverage form of the convex rib portions by the functional film are suitably adjusted. That is, the tip of the convex rib portions and the upper side of one or both side surfaces are covered by the functional film so as to envelop them, while the lower side of the side surface of the convex rib portions and the surface of the base portion are left open without being covered by the functional film. The functional film is then rounded and shaped to bulge in the width direction of the convex rib portions, enveloping the tip of the convex rib portions and the upper side surfaces of the side surfaces. Furthermore, the maximum width (W) of the grid, which is the sum of the convex rib portions and the functional film enveloping the convex rib portions, is adjusted to a value that is less than the maximum width (W) of the grid. ＭＡＸ ) is the width of the bottom of the ridge portion (W Ｂ The shape and size of the ridges and the functional film are adjusted so that the height (H) of the ridges is at least 100%. Furthermore, it is preferable to limit the area where the functional film covers the side surface of the ridges to a specific area on the upper side of the side surface (for example, a range of 25% to 80% of the height (H) of the ridges).

[0018] As a result, even when obliquely incident light having a large and wide range of incident angles is incident on the wire-grid polarization element, the transmittance (Tp) of the second polarized light (P-polarized light) through the wire-grid polarization element can be prevented from decreasing depending on the incident angle. Therefore, the product (Tp × Rs) of the reflection axis reflectance (Rs) of the first polarized light (S-polarized light) and the transmission axis transmittance (Tp) of the second polarized light (P-polarized light) through the wire-grid polarization element can be maintained at a high value. Therefore, when the wire-grid polarization element is used as, for example, a polarizing beam splitter, sufficient transmittance and polarization separation characteristics can be obtained even for obliquely incident light having a large and wide range of incident angles.

[0019] Incidentally, in imprint molding such as the above-mentioned nanoimprint, the fine concave-convex shape of the master is pressed against an uncured resin layer formed on a substrate, the uncured resin layer is cured in that state, and the master is peeled off, thereby forming a fine concave-convex shape on the substrate.

[0020] In imprint molding, if the thickness (layer thickness) of the uncured resin layer when pressed against the master is non-uniform, the peeling force applied when peeling the master from the cured resin layer (hereinafter referred to as the "cured resin layer") will be non-uniform within the plane of the cured resin layer. This may result in a portion of the cured resin layer peeling off from the substrate. Furthermore, the cured resin layer that has peeled off from the substrate may remain on the master, making it impossible to reuse the master. Furthermore, when peeling off the master, the fine concave-convex shape transferred to the cured resin layer may be deformed, potentially degrading the optical properties due to the fine concave-convex structure.

[0021] Furthermore, in imprint molding, if the uncured resin composition has poor conformability to the fine unevenness when the master is pressed against the resin, there will be areas in the uncured resin layer where the fine unevenness of the master is not transferred.

[0022] Therefore, in order to make the thickness of the uncured resin layer uniform when the master is pressed against it and to improve the ability of the uncured resin composition to conform to the fine unevenness, for example, Patent Documents 7 and 8 have developed technologies for lowering the viscosity of the uncured resin composition.

[0023] In order to lower the viscosity of the uncured resin composition, it is conceivable to increase the content of the monofunctional monomer and the low-viscosity difunctional monomer in the resin composition.

[0024] However, increasing the content of the monofunctional monomer and the low-viscosity bifunctional monomer causes a problem in that the heat resistance of the resin layer after curing decreases.

[0025] Therefore, the present invention has been made in consideration of the above circumstances, and aims to provide a wire grid polarizer with excellent heat resistance, a method for manufacturing the polarizer, and a projection display device and a vehicle equipped with the polarizer.

[0026] In order to solve the above-described problems, according to one aspect of the present invention, there is provided a wire grid polarization element comprising: a substrate made of an inorganic material; a grid structure made of an organic material, the grid structure having a base portion provided on the substrate and a plurality of ridge portions protruding from the base portion integrally formed therewith; and a functional film made of a metal material and covering a portion of the ridge portions, wherein the organic material is a cured product of a photocurable acrylic resin for imprinting containing a photopolymerizable component, the photopolymerizable component containing: a resin (A) and a resin (B), the resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, and the resin (B) is a bifunctional compound, the content of the resin (A) relative to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less, and the content of the resin (B) relative to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less.

[0027] The photopolymerizable component may further contain a resin (C), the resin (C) being an acrylate monomer having three or more functional groups, and the content of the resin (C) relative to the entire photopolymerizable component may be 1 mass % or more and 30 mass % or less.

[0028] The resin (A) may be one or both of phenylethyl acrylate and benzyl acrylate.

[0029] The resin (B) may be one or more selected from the group consisting of (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate, (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate, and 1,6-hexanediol diacrylate.

[0030] The resin (B) may contain 1,6-hexanediol diacrylate, and one of (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate and (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate.

[0031] The resin (C) may contain one or both of dipentaerythritol hexaacrylate and tris-(2-acryloxyethyl) isocyanurate.

[0032] The viscosity of the photocurable acrylic resin for imprints at 25° C. may be 90 mPa·s or less.

[0033] The cured product of the photocurable acrylic resin for imprints may have a YI value of 3.0 or less after being kept at 150°C for 500 hours.

[0034] The storage modulus of the cured product of the photocurable acrylic resin for imprints at 30°C is 2.0 × 10 ９ The storage modulus of the cured product at 120°C is 1.3 x 10 ８ It may be set to Pa or more.

[0035] The storage modulus of the cured product at 130°C is 1.4 × 10 ８ It may be set to Pa or more.

[0036] After maintaining a cured product of the photocurable acrylic resin for imprints at 150°C for 500 hours, the cured product may have an average transmittance of 91% or more for light in a wavelength region of 430 nm or more and 680 nm or less, and may have an average transmittance of 90% or more for light in a wavelength region of 430 nm or more and 510 nm or less.

[0037] The convex rib portion has a tapered shape that narrows in width as it moves away from the base portion, the functional film covers the tip of the convex rib portion and the upper side of at least one of the side surfaces, but does not cover the lower sides of both side surfaces of the convex rib portion or the base portion, and when the coverage rate (Rc) of the side surface of the convex rib portion by the functional film is the ratio of the height (Hx) of the part of the side surface of the convex rib portion covered by the functional film to the height (H) of the convex rib portion, the coverage rate (Rc) may be 30% or more and 70% or less.

[0038] At least the portion of the convex ridge that is covered with the functional film may be inclined at an inclination angle (α) of more than 0° and 15° or less with respect to the normal direction of the substrate.

[0039] The convex rib portion may be bent midway in the height direction of the convex rib portion, and the portion of the convex rib portion above the bent position may be inclined at the inclination angle (α) with respect to the normal direction of the substrate.

[0040] The entire convex ridge portion may be inclined at the inclination angle (α) with respect to the normal direction of the substrate.

[0041] The inclination angle (α) may be set to be equal to or greater than 5° and equal to or less than 10°.

[0042] The functional film may cover the tip and upper sides of both side surfaces of the convex rib portion, and the coverage rate (Rc) of the both side surfaces of the convex rib portion by the functional film may be 30% or more and 70% or less.

[0043] The coverage (Rc) of the first side surface of the ridge portion on the inclined side of the ridge portion may be 35% or more and 50% or less.

[0044] The coverage (Rc) of the first side surface may be 40% or more and 53% or less.

[0045] The coverage (Rc) of a second side surface of the ridge portion opposite the inclined side of the ridge portion may be 35% or more and 55% or less.

[0046] The coverage (Rc) of the second side surface may be 35% or more and 45% or less.

[0047] The thickness (TB) of the base portion may be 0.15 mm or less.

[0048] The thickness (TB) of the base portion may be 0.09 mm or less.

[0049] The thickness (TB) of the base portion may be 0.045 mm or less.

[0050] The thickness (TB) of the base portion may be 0.02 mm or less.

[0051] The wire grid polarizer may be a hybrid type that combines the substrate made of the inorganic material with the grid structure made of the organic material.

[0052] The surface of the functional film that encases the convex ridge portion is rounded and bulges out in the width direction of the convex ridge portion, and the maximum width (W ＭＡＸ ) is the width (W) of the part of the ridge that is not covered with the functional film at a position 20% above the bottom of the ridge. Ｂ ) or more.

[0053] The cross-sectional shape of the entire convex structure composed of the convex streak portion and the functional film may have a constricted portion in which the width of the entire convex structure in the width direction is narrowed directly below the lower end of the functional film that covers the convex streak portion.

[0054] The product (Tp×Rs) of the transmission axis transmittance (Tp) and the reflection axis reflectance (Rs) of light incident on the wire grid polarizer at an incident angle of 45° may be 70% or more.

[0055] The height (H) of the ridge portion may be 160 nm or more.

[0056] The thickness (Dt) of the functional film covering the tip of the ridge portion may be 5 nm or more.

[0057] The thickness (Ds) of the functional film covering the side surface of the protruding ridge may be set to 10 nm or more and 30 nm or less.

[0058] The thickness (TB) of the base portion may be 1 nm or more.

[0059] The cross-sectional shape of the convex ridges in a cross section perpendicular to the reflection axis direction of the wire grid polarizer may be a trapezoid, a triangle, a bell shape, or an ellipse whose width narrows with increasing distance from the base portion.

[0060] The device may further include a protective film formed so as to cover at least the surface of the functional film.

[0061] The protective coating may include a water-repellent or oil-repellent coating.

[0062] The functional film may further include a dielectric film.

[0063] When θ is 30° or more and 60° or less, the difference between the transmission axis transmittance (Tp(+)) of incident light having an incident angle of +θ to the wire-grid polarizer and the transmission axis transmittance (Tp(-)) of incident light having an incident angle of −θ may be within 3%.

[0064] The functional film may be a reflective film that reflects incident light.

[0065] The wire grid polarizer may be a polarizing beam splitter that splits obliquely incident light into a first polarized light and a second polarized light.

[0066] In order to achieve the above object, according to another aspect of the present invention, there is provided a method for manufacturing the above wire grid polarization element, comprising the steps of: forming a grid structure material made of an organic material on a substrate made of an inorganic material; forming a grid structure having a base portion provided on the substrate and a plurality of ridge portions protruding from the base portion by nanoimprinting the grid structure material; and forming a functional film using a metal material to cover a portion of the ridge portions, wherein the organic material is a cured product of a photocurable acrylic resin for imprinting containing a photopolymerizable component, and the photopolymerizable component includes: resin (A) and resin (B), wherein the resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, and the resin (B) is a bifunctional compound, and a content of the resin (A) with respect to the entire photopolymerizable component is 20 mass % or more and 42 mass % or less, The method for producing a wire-grid polarization element is provided, wherein the content of the resin (B) relative to the total photopolymerizable components is 43 mass % or more and 66 mass % or less.

[0067] The photocurable acrylic resin for imprinting may further contain a photopolymerization initiator for polymerizing the photopolymerizable component, and the step of forming the grid structure may include: mixing the resin (A) and the resin (B); and mixing the photopolymerization initiator into the mixed resin of the resin (A) and the resin (B).

[0068] The photopolymerizable component may further include a resin (C), which is an acrylate monomer having three or more functional groups, and the content of the resin (C) relative to the entire photopolymerizable component may be 1 mass % or more and 30 mass % or less, and the step of forming the grid structure may include: mixing the resin (A) and the resin (B) to produce a first mixed resin; and mixing the resin (C) with the first mixed resin to produce a second mixed resin.

[0069] In the step of forming the functional film, films may be formed alternately from a plurality of directions on the ridge portion by sputtering or vapor deposition.

[0070] In order to solve the above problem, according to another aspect of the present invention, there is provided a projection display device comprising: a light source; a polarizing beam splitter arranged so that incident light from the light source is incident at an incident angle within a predetermined range including 45°, and separating the incident light into a first polarized light and a second polarized light; a reflective liquid crystal display element arranged so that the first polarized light reflected by the polarizing beam splitter or the second polarized light transmitted through the polarizing beam splitter is incident, and reflecting and modulating the incident first polarized light or the second polarized light; and a lens arranged so that the first polarized light or the second polarized light reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter, wherein the polarizing beam splitter is constituted by the wire grid polarizer.

[0071] The predetermined range of incident angles may be equal to or greater than 30° and equal to or less than 60°.

[0072] A heat dissipation member may be provided around the wire grid polarizer.

[0073] In order to solve the above-mentioned problems, according to another aspect of the present invention, there is provided a vehicle equipped with the projection display device.

[0074] According to the present invention, a wire-grid polarizer having excellent heat resistance can be provided.

[0075] FIG. 1 is a cross-sectional view schematically showing a wire-grid polarization element according to a first embodiment of the present invention. FIG. 2 is a plan view schematically showing the wire-grid polarization element according to the same embodiment. FIG. 3 is a cross-sectional view schematically showing a specific example of a tapered shape of a convex portion of a grid structure according to the same embodiment. FIG. 4 is a cross-sectional view schematically showing a specific example of a shape of a concave portion of a grid structure according to the same embodiment. FIG. 5 is a cross-sectional view schematically showing a wire-grid polarization element according to the same embodiment. FIG. 6 is a cross-sectional view schematically showing a specific example of a shape of a reflective film according to the same embodiment. FIG. 7 is a cross-sectional view schematically showing a polarization element covered with a protective film according to the same embodiment. FIG. 8 is a cross-sectional view schematically showing a modified example of a polarization element covered with a protective film according to the same embodiment. FIG. 9 is a perspective view schematically showing a polarization element including a heat dissipation member according to the same embodiment. FIG. 10 is a photograph showing an actual grid structure and a reflective film according to the same embodiment. FIG. 11 is a process chart showing a method for manufacturing the wire-grid polarization element according to the same embodiment. FIG. 12 is a process chart showing a method for manufacturing a conventional wire-grid polarization element. FIG. 13 is a process chart showing a method for manufacturing a master according to the same embodiment. FIG. 14 is a schematic diagram showing a head-up display device as an example of the projection display device according to the embodiment. FIG. 15 is a schematic diagram showing a first specific example of the projection display device according to the embodiment. FIG. 16 is a schematic diagram showing a second specific example of the projection display device according to the embodiment. FIG. 17 is a schematic diagram showing a third specific example of the projection display device according to the embodiment. FIG. 18 is a cross-sectional view schematically showing a wire-grid polarizer according to a second embodiment of the present invention. FIG. 19 is a cross-sectional view schematically showing a modification of the wire-grid polarizer according to the second embodiment of the present invention. FIG. 20 is a diagram for explaining a polarizer according to Example 40. FIG. 21 is a diagram for explaining a polarizer according to Example 40. FIG. 22 is a diagram for explaining a polarizer according to Example 42. FIG. 23 is a diagram for explaining a polarizer according to Example 43. FIG. 24 is a diagram for explaining a polarizer according to Example 44.

[0076] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted. For ease of explanation, the states of the components disclosed in the following drawings may be represented schematically at different scales and shapes from the actual state.

[0077] 1. Overview of Wire-Grid Polarizer First, an overview of a wire-grid polarizer 1 according to a first embodiment of the present invention will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a cross-sectional view schematically showing the wire-grid polarizer 1 according to this embodiment. Fig. 2 is a plan view schematically showing the wire-grid polarizer 1 according to this embodiment.

[0078] The wire-grid polarizer 1 according to this embodiment is a reflective polarizer and a wire-grid polarizer. The wire-grid polarizer 1 may be, for example, a plate-shaped wire-grid polarizer. The wire-grid polarizer is a plate-shaped wire-grid polarizer. The wire-grid polarizer may be, for example, a flat plate-shaped or curved plate-shaped. In other words, the surface of the wire-grid polarizer 1 (the surface onto which light is incident) may be either flat or curved. An example in which the wire-grid polarizer 1 according to this embodiment is a flat wire-grid polarizer will be described below. However, the wire-grid polarizer of the present invention is not limited to this example and may have any shape depending on its application, function, etc.

[0079] The wire grid polarization element of the present invention may be used, for example, as a polarizer that transmits only light vibrating in one specific direction, or as a polarization beam splitter that separates incident light into a first polarization (S polarization) and a second polarization (P polarization). The following mainly describes an example in which the wire grid polarization element 1 according to this embodiment is used as a polarization beam splitter.

[0080] As shown in Figures 1 and 2, the wire-grid polarizer 1 (hereinafter sometimes abbreviated as "polarizer 1") includes a transparent substrate 10, a transparent grid structure 20, and an opaque functional film (e.g., a reflective film 30).

[0081] In this specification, "transparent" means that the transmittance of light of wavelength λ belonging to a used band (e.g., the visible light band, the infrared light band, or the visible and infrared light bands) is high, for example, the transmittance of the light is 70% or more. The wavelength band of visible light is, for example, 360 nm or more and 830 nm or less. The wavelength band of infrared light (infrared light) is wider than the wavelength band of visible light, for example, 830 nm or more. From the viewpoint of the suitable wavelength range of visible light projected as a display image, the wavelength λ of the used band in the polarizing element 1 according to this embodiment is, for example, preferably 400 nm or more and 800 nm or less, and more preferably 420 nm or more and 680 nm or less. The polarizing element 1 according to this embodiment is formed of a material transparent to light in the used band, and therefore does not adversely affect the polarization characteristics, light transmittance, etc. of the polarizing element 1.

[0082] The substrate 10 is made of a transparent inorganic material such as glass, etc. The substrate 10 is a flat substrate having a predetermined thickness TS.

[0083] The grid structure 20 is made of a transparent organic material, for example, an organic resin material such as an ultraviolet-curable resin or a thermosetting resin that has excellent heat resistance. The grid structure 20 has a concavo-convex structure for realizing the polarization function of the polarizing element 1. Specifically, the grid structure 20 has a base portion 21 provided along the surface of the substrate 10, and a plurality of ridge portions 22 that protrude in a grid pattern from the base portion 21. The base portion 21 and the plurality of ridge portions 22 of the grid structure 20 are integrally formed using the same organic material.

[0084] The base portion 21 is a thin film having a predetermined thickness TB, and is laminated over the entire main surface of the substrate 10 (the XY plane shown in FIGS. 1 and 2 ). The thickness TB of the base portion 21 is preferably substantially uniform over the entire main surface of the substrate 10, but it does not have to be exactly uniform and may vary with a certain degree of error from the reference thickness of TB. For example, TB may vary by approximately ±3 μm from the reference thickness of 6 μm. In this way, the thickness TB of the base portion 21 is determined, allowing for molding errors when molding the base portion 21 by imprinting or the like.

[0085] The plurality of convex ridges 22 are arranged on the base portion 21 at equal intervals in the X direction at a predetermined pitch P. The pitch P is the spacing between the plurality of convex ridges 22 arranged in the X direction of the polarizing element 1. The plurality of convex ridges 22 are arranged in a lattice pattern so as to extend parallel to each other in the Y direction. A predetermined gap is formed between two convex ridges 22 adjacent to each other in the X direction. This gap serves as a path for incident light to enter. Each convex ridge 22 is a wall-like convex portion formed to protrude and extend elongatedly in a predetermined direction (the Y direction shown in Figures 1 and 2). The height (H) in the Z direction and the width (W) in the X direction of the plurality of convex ridges 22 are Ｔ , W Ｂ ) are substantially identical to each other. The longitudinal direction (Y direction) of the ridge portion 22 is the direction of the reflection axis of the polarizing element 1, and the width direction (X direction) of the ridge portion 22 is the direction of the transmission axis of the polarizing element 1.

[0086] The functional film is a film for imparting a predetermined function to the grid structure 20 of the polarizing element 1. The functional film is made of, for example, an opaque metal material and is provided so as to cover a portion of the ridge portion 22 of the grid structure 20. The functional film may be, for example, a reflective film 30 that has the function of reflecting incident light that is incident on the polarizing element 1, or an absorbing film (not shown) that has the function of absorbing the incident light, or a film having other functions. In this embodiment, an example in which the functional film is a reflective film 30 will be described, but the functional film of the present invention is not limited to the example of a reflective film 30.

[0087] The reflective film 30 is a thin film made of a metallic material (metal or metal oxide, etc.) such as aluminum or silver. The reflective film 30 is formed so as to cover at least the tops of the protruding stripes 22. The reflective film 30 may be made of a metal film that functions as the thin metallic wires of the wire grid. The reflective film 30 has the function of reflecting incident light that is incident on the grid structure 20.

[0088] The convex ridges 22 of the grid structure 20 and the reflective film 30 constitute the grid of the wire-grid polarizer 1. The pitch P in the X direction of the multiple convex ridges 22 in the grid structure 20 (i.e., the grid arrangement pitch) is set to a pitch smaller than (e.g., equal to or smaller than half) the wavelength λ of incident light (e.g., visible light). This allows the polarizer 1 to reflect most of the light (S-polarized light) whose electric field vector component oscillates in a direction parallel to the reflective film 30 (conductor wire) extending in the Y direction (reflection axis direction: Y direction), and to transmit most of the light (P-polarized light) whose electric field vector component oscillates in a direction perpendicular to the reflective film 30 (conductor wire) (transmission axis direction: X direction).

[0089] As described above, the wire grid polarizer 1 according to this embodiment achieves polarization function by combining the grid structure 20 having a fine concave-convex structure with a functional film (e.g., reflective film 30) selectively added to the ridge portions 22 of the grid structure 20. The substrate 10 of the wire grid polarizer 1 is made of an inorganic material such as glass that has excellent heat resistance, and the grid structure 20 is made of an organic resin material that is also heat resistant. In this way, the wire grid polarizer 1 according to this embodiment is a hybrid polarizer that combines organic and inorganic materials. Therefore, the thermal resistance R [m ２ Heat can be efficiently dissipated from the grid structure 20, which has a small [K / W] ratio, to the substrate 10, resulting in excellent heat dissipation. Therefore, the hybrid wire-grid polarizer 1 according to this embodiment has excellent heat resistance and heat dissipation properties compared to conventional film-type polarizers made only of organic materials (heat resistance: approximately 100°C), and is heat resistant in high-temperature environments up to, for example, approximately 200°C. Therefore, excellent polarization characteristics can be achieved while maintaining a good heat dissipation effect.

[0090] Furthermore, the wire grid polarizer 1 according to this embodiment may include a protective film 40 (see FIGS. 7 and 8) that covers the surface of the grid structure 20. The protective film 40 is made of an inorganic material, for example, SiO ２ The protective film 40 may be laminated over the entire surface of the wire-grid polarizer 1 so as to cover the entire surfaces of the base portion 21, the ridge portions 22, and the reflective film 30 of the grid structure 20 (see FIG. 7 ). Providing such a protective film 40 has the advantageous effect of further reducing the thermal resistance R of the polarizer 1, thereby achieving excellent polarization characteristics while maintaining a better heat dissipation effect.

[0091] Furthermore, as described above, the grid structure 20, in which the base portion 21 and the ridge portions 22 are integrally configured, can be manufactured using a printing technique such as nanoimprinting, thereby achieving a fine uneven structure through a simple manufacturing process. Therefore, the cost and effort required to manufacture the grid structure 20 can be reduced compared to manufacturing using photolithography or etching techniques. Therefore, the hybrid polarizing element 1 according to this embodiment has the advantage of being able to significantly reduce manufacturing costs and lower the unit price of the wire-grid polarizing element 1 compared to conventional polarizing elements made only of inorganic materials.

[0092] On the other hand, conventional film-type organic polarizing plates use a large amount of organic materials, and the thickness of the substrate (base film), double-sided tape (OCA: Optically Clear Adhesive), and grid structure are large, so they are thought to have inferior heat dissipation and heat resistance compared to the hybrid-type polarizing element 1 according to this embodiment.

[0093] Furthermore, in the wire-grid polarization element 1 according to this embodiment, the grid, which is made up of the convex streak portions 22 of the grid structure 20 and the reflective film 30, has a special tree-like shape (details of which will be described later) as shown in FIG. 1 and other figures. This prevents the transmittance (i.e., transmission axis transmittance Tp) of the second polarized light (P-polarized light) passing through the polarization element 1 from decreasing depending on the incident angle θ of the obliquely incident light, even when light is incident on the polarization element 1 at a wide range of large incident angles θ (e.g., 30 to 60°). Therefore, the product (Tp × Rs) of the reflectance (i.e., reflection axis reflectance Rs) of the first polarized light (S-polarized light) reflected by the wire-grid polarization element 1 and the transmission axis transmittance Tp can be maintained at a high value, e.g., 70% or more. Therefore, the polarization element 1 according to this embodiment has excellent polarization separation characteristics expressed by Tp × Rs, and can polarize obliquely incident light and effectively separate it into S-polarized light (reflected light) and P-polarized light (transmitted light). Therefore, the polarizing element 1 according to this embodiment can obtain sufficient transmittance and polarization separation characteristics even for obliquely incident light with a large incident angle θ and over a wide range.

[0094] As described above, the wire-grid polarizer 1 according to this embodiment has excellent heat resistance and heat dissipation properties, can reduce manufacturing costs, and exhibits excellent transmittance and polarization separation characteristics for obliquely incident light with a wide range of large incident angles θ. Therefore, the wire-grid polarizer 1 according to this embodiment can be suitably used as a variety of components in a variety of products. For example, the polarizer 1 can be used as a polarizing beam splitter installed in a smart display. The polarizer 1 can also be used as a polarizing element installed in a head-up display (HUD) that is resistant to heat from sunlight, a polarizing element installed in a head-up display (HUD) that is resistant to heat from an LED light source, a polarizing reflective mirror, and the like. The polarizer 1 can also be used as a polarizing beam splitter installed in a headlight such as an adaptive beam distribution headlamp (ADB). The polarizer 1 can also be used as a lens-integrated retardation element or lens-integrated polarizing element installed in various devices for augmented reality (AR) or virtual reality (VR).

[0095] 2. Components of Wire-Grid Polarizer> Next, the components of the wire-grid polarizer 1 according to this embodiment will be described in detail with reference to FIGS. 1 and 2 .

[0096] 1, the wire-grid polarizer 1 according to this embodiment includes a transparent substrate 10. The substrate 10 is transparent and made of an inorganic material having a certain degree of strength.

[0097] As the material for the substrate 10, from the viewpoint of obtaining better heat dissipation and heat resistance, it is preferable to use an inorganic material such as various types of glass, quartz, crystal, sapphire, etc., more preferably an inorganic material having a thermal conductivity of 1.0 W / m·K or more, and even more preferably an inorganic material having a thermal conductivity of 8.0 W / m·K or more.

[0098] The shape of the substrate 10 is not particularly limited and can be selected appropriately depending on the performance required of the polarizing element 1. For example, it can be configured to have a plate shape or a curved surface. In order not to affect the polarization characteristics of the polarizing element 1, the surface of the substrate 10 can be made flat. Furthermore, the thickness TS of the substrate 10 is not particularly limited either and can be in the range of 0.02 to 10.0 mm, for example.

[0099] 1 and 2 , the polarizing element 1 according to this embodiment includes a grid structure 20 having the above-described base portion 21 and a grid-like ridge portion 22 on a substrate 10. The grid structure 20 can obtain desired polarization characteristics by providing a reflective film 30 (described later) on the ridge portion 22.

[0100] When light is incident on the polarizing element 1 from the front surface on which the grid structure 20 is formed, a portion of the incident light is reflected by the reflective film 30. Of the light incident on the reflective film 30, light having an electric field component in a direction perpendicular to the longitudinal direction of the ridges 22 (i.e., the extension direction of the ridges 22 = the reflection axis direction: Y direction) (i.e., the width direction of the ridges 22 = the transmission axis direction: X direction) is transmitted through the polarizing element 1 with high transmittance. On the other hand, of the light incident on the reflective film 30, light having an electric field component in a direction parallel to the longitudinal direction of the ridges 22 (i.e., the extension direction of the ridges 22 = the reflection axis direction: Y direction) is mostly reflected by the reflective film 30. Therefore, in this embodiment, a single polarization can be produced by providing the grid structure 20 partially covered with the reflective film 30. A similar polarization effect can also be achieved for light incident on the back surface of the substrate 10.

[0101] As shown in FIG. 1 , the grid structure 20 has a base portion 21. The base portion 21 is a thin film provided along the surface of the substrate 10 and serves to support the ridge portions 22. When the uneven structure (ridge portions 22) of the grid structure 20 is formed by nanoimprinting or the like, the base portion 21 is inevitably formed. The base portion 21 and the ridge portions 22 are integrally formed from the same material. Furthermore, since the grid structure 20 has the base portion 21, the strength of the ridge portions 22 can be increased compared to when the ridge portions 22 are formed directly on the substrate 10. This increases the durability of the grid structure 20. Furthermore, since the base portion 21 is in close contact with the substrate 10 over the entire surface, the peel resistance of the grid structure 20 can be improved.

[0102] The thickness TB of the base portion 21 is not particularly limited, but is preferably 1 nm or more, and more preferably 10 nm or more, from the viewpoint of more reliably supporting the ridge portion 22 and facilitating imprint molding. Furthermore, from the viewpoint of ensuring good heat dissipation, the thickness TB of the base portion 21 is preferably 50 μm or less, and more preferably 30 μm or less.

[0103] Furthermore, according to the polarizing element 1 of this embodiment, the base portion 21 and the multiple ridge portions 22 of the grid structure 20 are formed directly on the substrate 10, so that the thickness TB of the base portion 21 can be made thin. Here, in order to improve heat dissipation from the grid structure 20 to the substrate 10, it is preferable to reduce the temperature difference ΔT [°C] between the front and back surfaces of the base portion 21 by making the thickness TB of the base portion 21 thin. The temperature difference ΔT is the temperature difference between the temperature T1 [°C] of the outermost surface of the base portion 21 (the roots of the multiple ridge portions 22) and the temperature T2 [°C] of the base portion 21 at the interface between the base portion 21 and the substrate 10 (ΔT = T1 - T2).

[0104] Therefore, the thickness TB of the base portion 21 is preferably 0.15 mm or less. This allows heat from the grid structure 20, which is made of an organic material, to be quickly transferred to the substrate 10, which is made of an inorganic material, and efficiently dissipates heat from the substrate 10 to the outside of the polarizing element 1, thereby reducing the temperature difference ΔT to, for example, 32°C or less. Furthermore, the thickness TB of the base portion 21 is more preferably 0.09 mm or less, thereby reducing the temperature difference ΔT to, for example, 20°C or less. Furthermore, the thickness TB of the base portion 21 is more preferably 0.045 mm or less, thereby reducing the temperature difference ΔT to, for example, 10°C or less. Furthermore, the thickness TB of the base portion 21 is particularly preferably 0.02 mm or less, thereby reducing the temperature difference ΔT to, for example, 5°C or less. In this way, reducing the thickness TB of the base portion 21 improves heat dissipation from the grid structure 20 to the outside via the substrate 10, thereby improving the heat dissipation and heat resistance of the polarizing element 1.

[0105] 1 and 2, the grid structure 20 further has a plurality of ridges 22 protruding from the base 21. The ridges 22 extend longitudinally in the direction of the reflection axis (Y direction) of the polarizing element 1 according to this embodiment. The plurality of ridges 22 are arranged at a predetermined pitch in the X direction and at predetermined intervals from one another, thereby forming a grid-like uneven structure.

[0106] 1, in a longitudinal section (XZ section) perpendicular to the reflection axis direction (Y direction) of the polarizing element 1, the pitch P of the ridge portions 22 in the transmission axis direction (X direction) must be shorter than the wavelength of light in the band of light used. The reason for this is to obtain the polarization effect described above. More specifically, from the viewpoint of achieving both ease of manufacture of the ridge portions 22 and polarization properties, the pitch P of the ridge portions 22 is preferably 50 to 300 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm.

[0107] 1 and 2, the width W of the bottom of the convex rib portion 22 in the longitudinal section (XZ section) is Ｂ is not particularly limited, but is preferably about 10 to 150 nm, more preferably about 10 to 100 nm, from the viewpoint of achieving both ease of manufacturing and polarization characteristics. Ｔ is not particularly limited, but is preferably about 5 to 60 nm, more preferably about 10 to 30 nm, from the viewpoint of achieving both ease of manufacture and polarization characteristics.

[0108] The width W of the bottom of the ridge portion 22 Ｂ and the width of the top W Ｔ can be measured by observing with a scanning electron microscope or a transmission electron microscope. For example, a cross section (XZ cross section) perpendicular to the absorption axis direction or the reflection axis direction of the polarizing element 1 is observed using a scanning electron microscope or a transmission electron microscope, and the width of the convex rib portion 22 at any four positions is measured at a height position 20% above the height H of the convex rib portion 22 from the bottom of the convex rib portion 22, and the arithmetic average value of the widths is defined as the width W of the bottom of the convex rib portion 22. Ｂ Furthermore, for the four convex rib portions 22, the widths of the convex rib portions 22 are measured at a height position 20% below the height H of the convex rib portions 22 from the tip 22a of the convex rib portion 22, and the arithmetic mean value of the widths is defined as the width W of the top of the convex rib portion 22. Ｔ It can be said that:

[0109] 1 , the height H of the ridge portions 22 in the longitudinal cross section (XZ cross section) is not particularly limited, but is preferably about 50 to 350 nm, more preferably about 100 to 300 nm, from the viewpoint of achieving both ease of manufacture and polarization characteristics. The height H of the ridge portions 22 can be measured by observation with a scanning electron microscope or a transmission electron microscope. For example, a cross section perpendicular to the absorption axis direction or the reflection axis direction of the polarizing element 1 is observed using a scanning electron microscope or a transmission electron microscope, and the heights of the ridge portions 22 at the center positions in the width direction of the ridge portions 22 at any four positions are measured, and the arithmetic average value of these measurements can be used as the height H of the ridge portions 22.

[0110] The shape of the ridges 22 of the grid structure 20 is preferably tapered in order to obtain good polarization separation characteristics for obliquely incident light. Here, the tapered shape is a shape in which the width W (width in the X direction in the XZ cross section) of the ridges 22 gradually narrows with increasing distance from the base 21, in other words, a shape in which the width W of the ridges 22 gradually narrows from the bottom to the top of the ridges 22. Therefore, when the ridges 22 have a tapered shape, the width W of the top of the ridges 22 is Ｔ is the width W of the bottom of the ridge portion 22 Ｂ becomes smaller (W Ｔ <W Ｂ ).

[0111] 3 shows a specific example of the tapered shape of the ridge portion 22 according to this embodiment. As shown in FIG. 3, the cross-sectional shape of the ridge portion 22 in the longitudinal section (XZ section) may be various shapes, such as a trapezoid, a triangle, a bell shape, an ellipse, or a rounded wedge shape, in which the width W narrows with increasing distance from the base portion 21, as long as it is the above-mentioned tapered shape. For example, the cross-sectional shape of the ridge portion 22A shown in FIG. 3 is a trapezoid (tapered shape), the cross-sectional shape of the ridge portion 22B is a triangle, the cross-sectional shape of the ridge portion 22C is a bell shape, and the cross-sectional shape of the ridge portion 22D is a wedge shape with rounded top and bottom. In this way, since the convex rib portion 22 has a tapered shape, it is easy to form a reflective film 30 that covers the tip 22a and part of the side surface 22b of the convex rib portion 22, thereby imparting polarization properties to the polarizing element 1.In addition, since the tapered shape can also be formed by nanoimprinting, it is also advantageous in terms of ease of manufacturing.

[0112] Furthermore, since the ridge portions 22 have a tapered shape, such as a tapered shape, the refractive index of the grid structure 20 gradually changes. Therefore, similar to the moth-eye structure, an anti-reflection effect of incident light due to a change in the physical refractive index of the grid structure 20 is obtained. Therefore, it is possible to reduce the reflectance on the surface of the ridge portions 22 of the grid structure 20, and it is also expected that the transmittance of the grid structure 20 can be improved.

[0113] FIG. 4 also shows a specific example of the shape of the recess 24 formed between adjacent ridge portions 22, 22. The recess 24 is a groove extending in the longitudinal direction (Y direction) of the ridge portion 22. As shown in FIG. 4, the cross-sectional shape of the recess 24 in the longitudinal section (XZ section) may be various shapes as long as the width narrows toward the bottom of the recess 24. For example, the cross-sectional shape of the recess 24A shown in FIG. 4 is a trapezoid (tapered shape), the cross-sectional shape of the recess 24B is a triangle (V-shape), the cross-sectional shape of the recess 24C is a substantially rectangular shape with a flat bottom, and the cross-sectional shape of the recess 24D is a U-shape with a rounded bottom. The optimal shape of these recesses 24 can be selected appropriately taking into account productivity, such as mold releasability during nanoimprint formation.

[0114] Furthermore, the material constituting the grid structure 20 is not particularly limited as long as it is a transparent organic material, and any known organic material can be used. For example, from the viewpoints of ensuring transparency and excellent ease of manufacture, it is preferable to use various thermosetting resins, various ultraviolet curing resins, etc. as the material for the grid structure 20.

[0115] Furthermore, from the viewpoints of ease of manufacturing and manufacturing costs, it is preferable that the material constituting the grid structure 20 is different from that of the substrate 10. In addition, if the grid structure 20 and the substrate 10 are made of different materials, the refractive indexes of the two will be different. For this reason, if the refractive index of the entire polarizing element 1 is affected, a refractive index adjustment layer may be provided between the grid structure 20 and the substrate 10 as appropriate.

[0116] For example, curable resins such as epoxy polymerizable compounds and acrylic polymerizable compounds can be used as materials for forming the grid structure 20. Epoxy polymerizable compounds are monomers, oligomers, or prepolymers having one or more epoxy groups in the molecule. Examples of epoxy polymerizable compounds include various bisphenol-type epoxy resins (such as bisphenol A and F), novolac-type epoxy resins, various modified epoxy resins such as rubber and urethane, naphthalene-type epoxy resins, biphenyl-type epoxy resins, phenol novolac-type epoxy resins, stilbene-type epoxy resins, triphenolmethane-type epoxy resins, dicyclopentadiene-type epoxy resins, triphenylmethane-type epoxy resins, and prepolymers thereof.

[0117] The acrylic polymerizable compound is a monomer, oligomer, or prepolymer having one or more acrylic groups in the molecule. Here, the monomer is further classified into a monofunctional monomer having one acrylic group in the molecule, a bifunctional monomer having two acrylic groups in the molecule, and a polyfunctional monomer having three or more acrylic groups in the molecule.

[0118] Examples of "monofunctional monomers" include carboxylic acids (acrylic acid, etc.), hydroxyl groups (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate), alkyl or alicyclic monomers (isobutyl acrylate, t-butyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, cyclohexyl acrylate), and other functional monomers (2-methoxyethyl acrylate, methoxyethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, N,N-dimethylaminoethyl acrylate, methyl ... perfluorooctyl acrylate, N,N-dimethylaminopropyl acrylamide, N,N-dimethylacrylamide, acryloylmorpholine, N-isopropylacrylamide, N,N-diethylacrylamide, 2-(perfluorooctyl)ethyl acrylate, 3-perfluorohexyl-2-hydroxypropyl acrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate, 2-(perfluorodecyl)ethyl acrylate, 2-(perfluoro-3-methylbutyl)ethyl acrylate), 2,4,6-tribromophenol acrylate, 2,4,6-tribromophenol methacrylate, 2-(2,4,6-tribromophenoxy)ethyl acrylate), 2-ethylhexyl acrylate, and the like.

[0119] Examples of "bifunctional monomers" include tri(propylene glycol) diacrylate, trimethylolpropane diallyl ether, urethane diacrylate, etc. Examples of "polyfunctional monomers" include trimethylolpropane triacrylate, dipentaerythritol penta- and hexaacrylate, ditrimethylolpropane tetraacrylate, etc.

[0120] Examples of the acrylic polymerizable compounds other than those listed above include acrylic morpholine, glycerol acrylate, polyether acrylate, N-vinylformamide, N-vinylcaprolactam, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, polyethylene glycol acrylate, EO-modified trimethylolpropane triacrylate, EO-modified bisphenol A diacrylate, aliphatic urethane oligomer, and polyester oligomer.

[0121] Furthermore, examples of the curing initiator for the curable resin include a heat-curing initiator and a photo-curing initiator. The curing initiator may be one that is cured by heat, some kind of energy ray other than light (e.g., electron beam), or the like. When the curing initiator is a heat-curing initiator, the curable resin is a thermosetting resin, and when the curing initiator is a photo-curing initiator, the curable resin is a photo-curable resin.

[0122] Among these, it is preferable to use an ultraviolet curing initiator as the curing initiator. An ultraviolet curing initiator is a type of photocuring initiator. Examples of ultraviolet curing initiators include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl phenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one. Therefore, it is preferable that the curable resin is an ultraviolet curable resin. Furthermore, from the viewpoint of transparency, it is more preferable that the curable resin is an ultraviolet curable acrylic resin.

[0123] The method for forming the grid structure 20 is not particularly limited as long as it is a method that can form the above-described base portion 21 and ridge portions 22. For example, a concavo-convex forming method such as photolithography or imprinting can be used. Among these, it is preferable to form the base portion 21 and ridge portions 22 of the grid structure 20 by imprinting, from the viewpoints that the concavo-convex pattern can be formed easily in a short time and that the base portion 21 can be reliably formed.

[0124] When the base portion 21 and the ridge portions 22 of the grid structure 20 are formed by nanoimprinting, for example, a material for forming the grid structure 20 (grid structure material) is applied to the substrate 10, and then a master having projections and recesses formed thereon is pressed against the grid structure material, and in this state, ultraviolet light is irradiated or heat is applied to harden the grid structure material. In this way, the grid structure 20 having the base portion 21 and the ridge portions 22 can be formed.

[0125] 2.3. Reflective Film (Functional Film) As shown in FIGS. 1 and 2, the polarizing element 1 according to this embodiment includes a reflective film 30 formed on the ridge portions 22 of the grid structure 20.

[0126] 1, the reflective film 30 is formed so as to cover the tips 22a and parts of the side surfaces 22b of the ridge portions 22 of the grid structure 20. As shown in Fig. 1, the reflective film 30 is formed so as to extend along the longitudinal direction (Y direction) of the ridge portions 22 of the grid structure 20. This allows the reflective film 30 to reflect light that has entered the polarizing element 1 and that has an electric field component in a direction parallel to the longitudinal direction of the ridge portions 22 (reflection axis direction: Y direction).

[0127] The material constituting the reflective film 30 is not particularly limited as long as it is a material that is reflective to light in the used band, and examples thereof include metal materials such as simple metal elements such as Al, Ag, Cu, Mo, Cr, Ti, Ni, W, Fe, Si, Ge, and Te, and alloys containing one or more of these elements.

[0128] The reflective film 30 may be a single layer film made of the above metal, or may be a multi-layer film made of multiple metal films. The reflective film 30 may also include other layers, such as a dielectric film, as needed, as long as it has a reflective function. The dielectric film is a thin film made of a dielectric material. The material of the dielectric film is SiO ２ , Al ２ O ３ , MgF ２ , TiO ２Common materials such as the above can be used. The refractive index of the dielectric film is preferably greater than 1.0 and equal to or less than 2.5. Since the optical characteristics of the reflective film 30 are also affected by the refractive index of the surroundings, the polarization characteristics may be controlled by the material of the dielectric film.

[0129] 2.4. Special Shapes of the Convex Strips and Reflective Film The special shapes of the convex strips 22 of the grid structure 20 and the reflective film 30 in the polarizing element 1 according to this embodiment will now be described in detail.

[0130] 1 and 5, in the polarizing element 1 according to this embodiment, the reflective film 30 is formed so as to cover the tips 22a and the upper side of at least one of the side surfaces 22b of the convex rib portions 22 of the grid structure 20, but not to cover the lower sides of both side surfaces 22b of the convex rib portions 22 or the base portion 21. In the example shown in Fig. 1 and 5, the reflective film 30 covers the upper sides of both side surfaces 22b of the convex rib portions 22, but it may also cover the upper side of only one of the side surfaces 22b of the convex rib portions 22.

[0131] 1 and 5, the phrase "a state in which the reflective film 30 covers the tip 22a of the convex rib portion 22 and the upper side of at least one of the side surfaces 22b" means a state in which the reflective film 30 continuously covers both the "tip 22a of the convex rib portion 22" and the "upper side of the side surface 22b connecting the tip 22a of the convex rib portion 22 and the base portion 21," while leaving the "lower side of the side surface 22b" and the "base portion 21" exposed and not covered by the reflective film 30. In this state, the reflective film 30 does not cover the entire side surface 22b of the convex rib portion 22 (all of the side surfaces 22b from the tip 22a of the convex rib portion 22 to the base portion 21).

[0132] Furthermore, the surface of the reflective film 30 that covers the tip 22a and the upper side of at least one of the side surfaces 22b of the convex rib portion 22 (hereinafter, sometimes referred to as the "top of the convex rib portion 22") has a rounded, curved shape (for example, a vertically elongated, approximately elliptical shape) and bulges out in the width direction (X direction) of the convex rib portion 22. In this way, the surface of the reflective film 30 has a rounded, smoothly curved shape and does not have sharp corners or steps. The maximum width W of the reflective film 30 that covers the top of the convex rib portion 22 in this way is ＭＡＸis the width W of the bottom of the ridge portion 22 Ｂ That's all. Furthermore, W ＭＡＸ Is W Ｂ It is preferable that it is greater than .

[0133] Here, the maximum width W of the reflective film 30 that covers the ridge portion 22 ＭＡＸ is the maximum horizontal width of the horizontal widths of the outermost surfaces of both sides of the reflective film 30 in the width direction (X direction) of the ridge portion 22. As shown in Figures 1 and 5, the horizontal widths (width in the X direction) of the outermost surfaces of both sides of the reflective film 30 that cover the ridge portion 22 vary depending on the height position (height in the Z direction) of the reflective film 30, but the maximum value of these horizontal widths is the maximum width W ＭＡＸ In other words, the maximum width W ＭＡＸ is the maximum value of the total width of the thickness Ds×2 of the reflective film 30 on both sides and the horizontal width W of the ridge portion 22. For example, when light is incident on the grid structure 20 from the front direction (Z direction) (when the incident angle θ is 0°), W ＭＡＸ corresponds to the effective grid width of the reflective film 30.

[0134] Width W of the bottom of the ridge portion 22 Ｂ 1 and 3, is the horizontal width (width in the X direction) of the convex rib portion 22 at a height position (height in the Z direction) 20% above the height H of the convex rib portion 22 from the lowest part of the convex rib portion 22 (the upper surface of the base portion 21). In other words, the width W of the bottom of the convex rib portion 22 Ｂ is the horizontal width of the ridge portion 22 at a height of 0.2×H above the top surface of the base portion 21.

[0135] The width W of the top of the ridge portion 22 Ｔ 1 and 3, is the horizontal width (width in the X direction) of the ridge portion 22 at a height position (height in the Z direction) 20% below the height H of the ridge portion 22 from the tip 22a of the ridge portion 22. In other words, the width W of the top of the ridge portion 22 Ｔ is the horizontal width of the ridge portion 22 at a position 0.8×H above the top surface of the base portion 21 (i.e., a position 0.2×H below the tip 22a of the ridge portion 22).

[0136] In the following description, the convex structure formed by combining the convex streak portion 22 and the reflective film 30 will be referred to as a "grid," and the height of the convex structure formed by combining the convex streak portion 22 and the reflective film 30 (i.e., the grid) will be referred to as a "grid height." ＭＡＸ "Grid maximum width W ＭＡＸ ", and the width W of the bottom of the ridge portion 22 Ｂ "Grid bottom width W Ｂ The width W of the top of the ridge portion 22 is also called Ｔ The width of the top of the ridge W Ｔ The width of the ridge portion 22 at the center position in the height direction is sometimes referred to as the "ridge portion center width."

[0137] In this manner, in this embodiment, the width W of the bottom of the ridge portion 22 Ｂ The horizontal width of the ridge portion 22 at a height position 20% above the lowest part (bottom) of the ridge portion 22 is used as the width W of the top of the ridge portion 22. Ｔ The horizontal width of the ridge portion 22 at a height position 20% below the tip 22 a of the ridge portion 22 is used as the horizontal width of the ridge portion 22. The reason for this is that the width of the bottom of the ridge portion 22 on the upper surface of the base portion 21 and the width of the tip 22 a of the ridge portion 22 vary greatly depending on the manufacturing conditions of the grid structure 20, and it is difficult to measure these widths precisely.

[0138] As described above, the grid structure 20 according to this embodiment is formed with tapered ridge portions 22 and a reflective film 30 that covers only the tips 22 a and the upper sides of the side surfaces 22 b of the ridge portions 22. The lower sides of the side surfaces 22 b of the ridge portions 22 are not covered with the reflective film 30 and are open.

[0139] As a result, the cross-sectional shape of the convex streak portion 22 covered with the curved reflective film 30 (i.e., the cross-sectional shape of the grid) has the following special cross-sectional shape. That is, as shown in Figures 1 and 5, the horizontal width of the upper part of the convex streak portion 22 where the reflective film 30 is present (for example, the maximum grid width W ＭＡＸ ) is large, and the horizontal width of the part from the center to the bottom side of the exposed ridge portion 22 that is not covered with the reflective film 30 (for example, the width W Ｂ) is smaller. The cross-sectional shape of the entire convex structure (i.e., "grid") composed of the convex rib portions 22 and the reflective film 30 is constricted inward at a position directly below the lower end of the curved reflective film 30, with the constricted portion having a narrower width in the X direction. Such a special cross-sectional shape of the grid can be likened to the shape of a tree. Specifically, the large, rounded leaves of the tree correspond to the portion of the reflective film 30 that covers the top of the convex rib portions 22, the trunk of the tree corresponds to the lower portion of the convex rib portions 22 that is not covered by the reflective film 30, and the ground on which the tree grows corresponds to the base portion 21. Therefore, in the following description, the special cross-sectional shape of the grid composed of the convex rib portions 22 and the reflective film 30 of the grid structure 20 described above will be referred to as a "special tree shape."

[0140] The grid of the grid structure 20 of the polarizing element 1 according to this embodiment has the special tree shape as described above. As a result, for example, when incident light is incident on the polarizing element 1 from an oblique direction, the effective grid width W Ａ becomes smaller, and the gap width W Ｇ Here, the effective grid width W Ａ is the width of the reflective film 30 in the direction perpendicular to the obliquely incident light. Ｇ is the gap between the reflective films 30 of two adjacent grids, and is the width of the gap in the direction perpendicular to the obliquely incident light. Ａ As the gap width W is larger, the obliquely incident light is more likely to be reflected by the reflective film 30 and less likely to reach the transparent ridge portion 22 or the base portion 21. Therefore, the transmittance of the obliquely incident light in the polarizing element 1 decreases. Ｇ The larger the value of , the more easily the obliquely incident light can pass between the two adjacent reflective films 30, 30 and reach the transparent ridge portion 22 and the base portion 21. Therefore, the transmittance for obliquely incident light can be increased.

[0141] Therefore, since the grid of the polarizing element 1 according to this embodiment has the above-mentioned special tree shape, the gap width W Ｇbecomes larger, and the obliquely incident light passes through the gaps between the round reflective films 30, 30, reaches the transparent grid structure 20, and is easily transmitted. Therefore, the transmission axis transmittance Tp of the obliquely incident light is high, and the transmittance and polarization separation characteristics (Tp×Rs characteristics) for the obliquely incident light are very excellent. Furthermore, a good balance can be achieved between the function of reflecting the obliquely incident light by the reflective film 30 and the function of transmitting the obliquely incident light by the grid structure 20, and the polarization separation characteristics for the obliquely incident light can be further improved.

[0142] 2.5. Method of forming reflective film and specific example Here, a method of forming the reflective film 30 will be described with reference to FIG.

[0143] As a method for forming the reflective film 30 so that it covers the tips 22 a and parts of both side surfaces 22 b of the ridge portions 22 of the grid structure 20, it is preferable to form the reflective film 30 by alternately sputtering or vapor deposition from an oblique direction (film deposition incident angle φ) relative to the ridge portions 22 of the grid structure 20, as shown in Fig. 5. This allows the reflective film 30 to be formed so as to cover the tips 22 a and the upper sides of both side surfaces 22 b of the ridge portions 22. The film deposition incident angle φ for forming the reflective film 30 by sputtering or vapor deposition is not particularly limited, but can be, for example, about 5 to 70° with respect to the surface of the substrate 10.

[0144] As described above, in this embodiment, after forming the grid structure 20 made of a transparent material, the reflective film 30 made of a metal material is formed by sputtering or vapor deposition. This allows for easy adjustment of the deposition conditions, material, and film thickness of the reflective film 30. Furthermore, it is also easy to accommodate a multilayer reflective film 30. Therefore, by combining metals, semiconductors, and dielectrics, it is possible to design a film that utilizes interference effects. Therefore, when forming the reflective film 30 by etching, as in the prior art, it is not necessary to consider the composition of materials that can be etched. This makes it easy to adjust the reflectance of polarized light parallel to the grid structure 20 and the transmittance (transmission amount) of polarized light perpendicular to the grid. In addition, by forming the reflective film 30 after forming the grid structure 20, there is no need for equipment such as a vacuum dry etching device, and there is no need to prepare safety devices such as gases and abatement devices tailored to complex processes and etching materials. This reduces running costs, such as capital investment and maintenance, and provides cost benefits.

[0145] The thickness Dt of the reflective film 30 covering the tips 22a of the ridge portions 22 shown in FIG. 5 and the thickness Ds of the reflective film 30 covering the side surfaces 22b of the ridge portions 22 are not particularly limited and can be changed appropriately depending on the shape of the ridge portions 22 of the grid structure 20, the performance required of the reflective film 30, and the like. For example, from the viewpoint of obtaining better reflective performance, the thicknesses Dt and Ds of the reflective film 30 are preferably 2 to 200 nm, more preferably 5 to 150 nm, even more preferably 10 to 100 nm, and particularly preferably 15 to 80 nm. The thickness Ds of the reflective film 30 is the thickness of the thickest portion of the reflective film 30 covering the side surfaces 22b of the ridge portions 22, as shown in FIG. 5.

[0146] Furthermore, the shape of the reflective film 30 is not particularly limited as long as it is a shape that can form the special tree shape described above, and can be selected appropriately depending on the conditions of the equipment used to form the reflective film 30 and the performance required of the reflective film 30.

[0147] Fig. 6 is a cross-sectional view schematically showing a specific example of the shape of the reflective film 30. As shown in Fig. 6, the reflective film 30 may have various shapes as long as it is curved so as to enclose the top of the protruding ridge portion 22 (the tip 22a and the upper side of the side surface 22b).

[0148] For example, the reflective film 30A shown in Figure 6 covers the tops of the ridges 22A, 22B, and 22C of various cross-sectional shapes in a rounded manner, and has a generally elliptical shape that bulges significantly in the width direction of the ridges 22. The reflective film 30B has a curved shape that covers the top of the generally wedge-shaped ridge 22D. The reflective film 30C has a curved shape that covers the top of the trapezoidal ridge 22A. The coverage rate Rc of one side surface 22b of the ridge 22 by these reflective films 30B and 30C is generally the same as the coverage rate Rc of the other side surface 22b.

[0149] Furthermore, the reflective film 30D envelops and covers the top of the approximately wedge-shaped ridge portion 22D, but is unevenly distributed on one side surface 22b of the ridge portion 22 (the left side surface 22b shown in FIG. 6 ). Specifically, the reflective film 30D covers a wide area of ​​the left side surface 22b of the ridge portion 22, with a coverage rate Rc of approximately 80%. On the other hand, the reflective film 30D only covers a narrow area on the upper side of the right side surface 22b, with a coverage rate Rc of approximately 25%. In this way, the coverage rate Rc of the reflective film 30D may differ between one side surface 22b and the other side surface 22b of the ridge portion 22.

[0150] 2.6. Suitable Range of Coverage Rc of the Convex Strip Portion by the Reflective Film Next, a suitable range of the coverage Rc of the side surface 22b of the convex strip portion 22 by the reflective film 30 according to this embodiment will be described.

[0151] The coverage ratio Rc is preferably 25% or more and 80% or less. Here, the coverage ratio Rc is the ratio of the height (Hx) of the portion of the side surface 22b of the protrusion 22 that is covered by the reflective film 30 to the height (H) of the protrusion 22 shown in Figures 1 and 5. The coverage ratio Rc is expressed by the following formula (1).

[0152] Rc [%] = (Hx / H) x 100 (1) H: height of the ridge portion 22 in the Z direction Hx: height of the portion of the side surface 22b of the ridge portion 22 covered with the reflective film 30 in the Z direction

[0153] The open area ratio Rr is the ratio of the height (H-Hx) of the portion of the side surface 22b of the protruding portion 22 that is not covered with the reflective film 30 to the height (H) of the protruding portion 22 shown in Figures 1 and 5. The open area ratio Rr is expressed by the following formula (2).

[0154] Rr[%]=((H-Hx) / H)×100...(2)

[0155] According to the above definition, Rr = 100 - Rc. Therefore, when the coverage rate Rc of the side surface 22b of the convex ridge portion 22 by the reflective film 30 is 25% or more and 80% or less, the open area rate Rr of the side surface 22b of the convex ridge portion 22 by the reflective film 30 is 20% or more and 75% or less.

[0156] As described above, in the polarizing element 1 according to this embodiment, the coverage Rc of the side surfaces 22b of the ridge portions 22 by the reflective film 30 is preferably 25% or more and 80% or less (i.e., the open area ratio Rr is 20% or more and 75% or less). In particular, in this embodiment, the reflective film 30 is formed so as to cover the tips 22a and the upper sides of both side surfaces 22b of the ridge portions 22, and to leave the lower sides of both side surfaces 22b uncovered and open. The coverage Rc is preferably 25% or more and 80% or less, more preferably 30% or more and 70% or less, and even more preferably 40% or more and 50% or less.

[0157] With this configuration, the polarizing element 1 according to this embodiment can exhibit sufficient transmittance even for obliquely incident light with a large incident angle θ (e.g., 45 to 60°). For example, when the polarizing element 1 separates obliquely incident light into S-polarized light (reflected light) and P-polarized light (transmitted light), the transmittance Tp of the P-polarized light (transmitted light) passing through the polarizing element 1 can be maintained at a high value, regardless of the incident angle θ of the obliquely incident light. Furthermore, by setting the coverage Rc to 25% or more and 80% or less, the contrast (CR = Tp / Ts), which is the ratio of the transmission axis transmittance (Tp) to the transmission axis reflectance (Ts), can be maintained at a good level, and the reflective action of the reflective film 30 can be more reliably exhibited, regardless of the incident angle θ of the obliquely incident light. Therefore, high transmittance of transmitted light can be ensured, and polarization separation characteristics can be improved, regardless of the incident angle θ of the obliquely incident light.

[0158] In contrast, as a comparative example, when the reflective film 30 is formed so as to cover only the tips 22 a of the protruding rib portions 22 of the grid structure 20, or when the reflective film 30 is formed so as to cover the entire tips 22 a and one side surface 22 b of the protruding rib portions 22, the variation in transmittance Tp becomes large depending on the incidence angle θ of the obliquely incident light, and it is considered that sufficient transmittance cannot be obtained even for obliquely incident light with a large incidence angle θ. Also, as a comparative example, when the reflective film 30 covers the entire tips 22 a and both side surfaces 22 b of the protruding rib portions 22 of the grid structure 20 (when the coverage rate Rc is 100%), the transmittance decreases significantly as the incidence angle θ of the obliquely incident light increases.

[0159] Therefore, from the viewpoint of improving the transmittance and polarization separation characteristics of transmitted light without depending on the incident angle θ of obliquely incident light, it is preferable to cover the tip 22a of the convex rib portion 22 and at least a portion of one of the side surfaces 22b (the upper side of the side surface 22b) with a reflective film 30, as in the polarizing element 1 of this embodiment.

[0160] Furthermore, from the viewpoint of the Tp×Rs characteristics required for a polarizing beam splitter (PBS), in the polarizing element 1 of this embodiment, it is preferable that the coverage rate Rc of the side surface 22b of the convex streak portion 22 by the reflective film 30 is 25% or more and 80% or less.

[0161] If the coverage Rc is less than 25%, the transmission axis transmittance Tp of P-polarized light passing through the polarizing element 1 decreases, the transmittance Tp varies depending on the incident angle θ, and a sufficiently high Tp × Rs value cannot be obtained. Therefore, for obliquely incident light with a large incident angle θ, sufficient transmittance of the transmitted light and the polarization separation characteristics expressed by Tp × Rs cannot be obtained. On the other hand, if the coverage Rc is greater than 80%, the transmission axis transmittance Tp decreases as the incident angle θ of the obliquely incident light increases (e.g., 45 to 60°), as in the case where the tip 22a and both side surfaces 22b of the protrusion 22 of the grid structure 20 are entirely covered, resulting in a large variation in the transmittance Tp depending on the incident angle θ.

[0162] Therefore, the coverage Rc of the side surface 22b of the ridge portion 22 by the reflective film 30 is preferably 25% or more and 80% or less. As a result, when light is incident on the polarizing element 1 from an oblique direction, for example, at an incident angle θ of 45°, the transmission axis transmittance Tp of the second polarized light (P polarized light) passing through the polarizing element 1 can be 75% or more. As a result, Tp × Rs can be 70% or more. Therefore, even when a wide range of obliquely incident light is incident at a large incident angle θ, the transmittance of the second polarized light (P polarized light) in the transmission axis direction of the polarizing element 1 can be increased, improving the polarization separation characteristics of the polarizing element 1 and allowing the polarizing element 1 to suitably separate the obliquely incident light into the first polarized light (S polarized light) and the second polarized light (P polarized light).

[0163] From the same viewpoint, it is more preferable that the coverage Rc is 30% or more and 70% or less (i.e., the open area Rr is 30% or more and 70% or less). As a result, under the above-mentioned oblique incidence conditions, a high transmittance Tp of 80% or more can be obtained, and a high Tp×Rs of 72% or more can be obtained. Furthermore, it is more preferable that the coverage Rc is 30% or more and 60% or less (i.e., the open area Rr is 40% or more and 70% or less). As a result, under the above-mentioned oblique incidence conditions, a high transmittance Tp of 83% or more can be obtained, and a high Tp×Rs of 75% or more can be obtained. Furthermore, it is even more preferable that the coverage Rc is 40% or more and 50% or less (i.e., the open area Rr is 50% or more and 60% or less). As a result, under the above-mentioned oblique incidence conditions, an extremely high transmittance Tp of 85% or more can be obtained, and a very high Tp×Rs of 77% or more can be obtained.

[0164] Furthermore, with regard to the reflection axis reflectance Rs, it is preferable that the coverage Rc is 20% or more, which makes it possible to obtain a high reflectance Rs of 85% or more under the above-mentioned oblique incidence conditions.

[0165] Furthermore, with regard to the contrast CR of transmitted light (CR=Tp / Ts), a sufficient contrast CR can be obtained if the coverage Rc is 20% or more. The higher the coverage Rc, the higher the contrast CR can be obtained.

[0166] 2.7. Preferred Range of Tp×Rs Next, a preferred range of “Tp×Rs,” which is an index representing the polarization separation characteristics of the wire-grid polarizer 1 according to this embodiment, will be described.

[0167] Tp×Rs [%] is the product of the transmission axis transmittance (Tp) and the reflection axis reflectance (Rs) expressed as a percentage. This Tp×Rs is an index representing the polarization separation characteristics of the wire grid polarizer 1. Tp×Rs [%] = (Tp [%] / 100) × (Rs [%] / 100) × 100

[0168] As described above, the transmission axis transmittance (Tp) is the transmittance of the second polarized light (P-polarized light) having an electric field component parallel to the transmission axis (X-direction) of the polarizing element 1. The reflection axis reflectance (Rs) is the reflectance of the first polarized light (S-polarized light) having an electric field component parallel to the reflection axis (Y-direction) of the polarizing element 1.

[0169] When the wire grid polarization element 1 according to this embodiment is used as a polarization beam splitter to separate incident light into S-polarized light and P-polarized light (see FIGS. 15 to 17 ), the polarization element 1 is positioned at a predetermined angle (e.g., 45°) with respect to the incident light from the light source. For example, when the incident light from the light source is incident on the polarization element 1 at an incident angle θ of approximately 45°, the incident light is separated by the polarization element 1 into a first polarization (S-polarized light: reflected light) and a second polarization (P-polarized light: transmitted light). The S-polarized light is incident light having an electric field component parallel to the longitudinal direction of the ridges 22 of the grid structure 20 (the reflection axis direction: Y direction shown in FIG. 2 ). On the other hand, the P-polarized light is incident light having an electric field component parallel to the width direction of the ridges 22 of the grid structure 20 (the transmission axis direction: X direction shown in FIG. 2 ).

[0170] The S-polarized light in the reflection axis direction mainly becomes reflected light reflected by the reflective film 30 of the polarizing element 1. The reflectance [%] of the S-polarized light at this time is the reflection axis reflectance (Rs). The reflection axis reflectance (Rs) represents the proportion of S-polarized light that is reflected by the polarizing element 1 out of the S-polarized light that enters the polarizing element 1. The reflection axis transmittance (Rp) represents the proportion of S-polarized light that is transmitted through the polarizing element 1 out of the S-polarized light that enters the polarizing element 1.

[0171] On the other hand, P-polarized light in the transmission axis direction mainly becomes transmitted light that passes through the transparent grid structure 20 and substrate 10 of the polarizing element 1. The transmittance [%] of the P-polarized light at this time is the transmission axis transmittance (Tp). The transmission axis transmittance (Tp) represents the proportion of P-polarized light that is transmitted through the polarizing element 1 out of the P-polarized light that is incident on the polarizing element 1. The transmission axis reflectance (Ts) represents the proportion of P-polarized light that is reflected by the polarizing element 1 out of the P-polarized light that is incident on the polarizing element 1.

[0172] Therefore, a higher transmission axis transmittance Tp means that P-polarized light in the transmission axis direction can be transmitted more efficiently. Also, a higher reflection axis reflectance Rs means that S-polarized light in the reflection axis direction can be reflected more efficiently. Therefore, the higher the Tp×Rs value, which is the product of Tp and Rs, the higher the transmittance of P-polarized light (transmitted light) and the reflectance of S-polarized light (reflected light), resulting in excellent polarization separation characteristics as a polarizing beam splitter.

[0173] Here, a preferred range of the value of Tp×Rs according to this embodiment will be described. Consider a case in which light of a predetermined wavelength range (e.g., 430 to 680 nm) is incident on the polarizing element 1 according to this embodiment from an oblique direction at a predetermined incident angle θ (e.g., 45°), and is separated into P-polarized light (transmitted light) and S-polarized light (reflected light). Under such oblique incidence conditions, from the viewpoint of good polarization separation characteristics of the polarizing element 1, it is preferable that Tp×Rs be 70% or more.

[0174] If Tp×Rs is less than 70%, the light utilization efficiency is poor in a display device to which the polarizing element is applied, the brightness of the displayed image is insufficient, and visibility is poor. In contrast, if Tp×Rs is 70% or more, the light utilization efficiency in a display device to which the polarizing element 1 is applied can be increased, sufficient brightness of the displayed image can be ensured, and visibility can be improved.

[0175] Furthermore, Tp×Rs is more preferably 72% or more, even more preferably 75% or more, and particularly preferably 80% or more, which can further improve the light utilization efficiency and the brightness and visibility of the displayed image.

[0176] <2.8. Preferred Range of Height H of Convex Rib Portion> When incident light is incident on the polarizing element 1 according to this embodiment at a relatively large incident angle θ (for example, 45°), the height H (see FIGS. 1, 3, etc.) of the convex rib portion 22 of the grid structure 20 is preferably 160 nm or more, more preferably 180 nm or more, and particularly preferably 220 nm or more. This makes it possible to obtain a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and a high contrast CR of transmitted light.

[0177] Specifically, with regard to transmittance, if the height H of the ridge portion 22 is 160 nm or more, the transmission axis transmittance Tp of obliquely incident light becomes 80% or more, resulting in high transmittance. Furthermore, if H is 180 nm or more, a Tp of 85% or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, a Tp of 87% or more can be obtained, which is particularly preferable.

[0178] Furthermore, with regard to the Tp×Rs characteristics required for a polarization beam splitter (PBS), if the height H of the ridge portion 22 is 160 nm or more, an excellent Tp×Rs of 70% or more can be obtained. Furthermore, if H is 180 nm or more, a Tp×Rs of 75% or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, a Tp×Rs of 77% or more can be obtained, which is particularly preferable.

[0179] Furthermore, with regard to the contrast CR (CR = Tp / Ts) of transmitted light, the height H of the ridge portion 22 needs to be 100 nm or more, but if H is 160 nm or more, an excellent contrast CR of 150 or more can be obtained. Furthermore, if H is 180 nm or more, an excellent CR of 250 or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, an excellent CR of 500 or more can be obtained, which is particularly preferable.

[0180] As described above, it can be seen that a larger height H of the ridge portions 22 is preferable for improving various characteristics (Tp, Tp×Rs, CR) of the polarizing element 1, particularly Tp. The reason for this is believed to be as follows. That is, when the deposition incident angle φ (see FIG. 5 ) is the same when the reflective film 30 is deposited on the ridge portions 22 by sputtering, vapor deposition, or the like, the lower the height H of the ridge portions 22, the greater the coverage Rc of the reflective film 30. As the coverage Rc increases, the area of ​​the ridge portions 22 covered by the reflective film 30 becomes wider, making it more difficult for P-polarized light to pass through the grid structure 20, and thus reducing the transmittance Tp. Therefore, under the condition that the deposition incident angle φ is the same, it is preferable to increase the height H of the ridge portions 22 to reduce the coverage Rc and increase the transmittance Tp.

[0181] <2.9. Preferred Range of Tip Thickness Dt of Functional Film (Reflective Film)> When incident light is incident on the polarizing element 1 according to this embodiment at a relatively large incident angle θ (for example, 45°), the thickness Dt of the reflective film 30 covering the tips 22 a of the protruding stripes 22 of the grid structure 20 (tip thickness Dt of the reflective film 30: see FIG. 5 ) is preferably 5 nm or more, and more preferably 15 nm or more.

[0182] If the tip thickness Dt of the reflective film 30 is 5 nm or more, both the reflection axis reflectance Rs and the transmission axis transmittance Tp of obliquely incident light will be 85% or more, resulting in high transmittance. Furthermore, when the Tp characteristics and the Tp×Rs characteristics required for a polarizing beam splitter are taken into consideration, it is more preferable that Dt be 15 nm or more.

[0183] <2.10. Suitable range of side thickness Ds of functional film (reflective film)> Furthermore, the thickness Ds of the reflective film 30 covering the side surfaces 22b of the protruding stripes 22 of the grid structure 20 (side surface thickness Ds of the reflective film 30: see FIG. 5) is preferably 10 nm or more and 30 nm or less, more preferably 12.5 nm or more and 25 nm or less, and particularly preferably 15 nm or more and 25 nm or less. This makes it possible to obtain a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and a high contrast CR of transmitted light.

[0184] Specifically, when the side thickness Ds of the reflective film 30 is 10 nm or more and 30 nm or less, the transmission axis transmittance Tp of obliquely incident light becomes 80% or more, and high transmittance is obtained. Furthermore, when Ds is 12.5 nm or more and 25 nm or less, Tp of 85% or more can be obtained, which is more preferable.

[0185] Regarding reflectivity, if the side thickness Ds of the reflective film 30 is 10 nm or more, the reflection axis reflectivity Rs of obliquely incident light becomes 80% or more, and high reflectivity is obtained. Furthermore, if Ds is 12.5 nm or more, Rs of 85% or more can be obtained, which is more preferable.

[0186] Regarding the Tp×Rs characteristics required for a polarizing beam splitter (PBS), an excellent Tp×Rs of 70% or more can be obtained if the side thickness Ds of the reflective film 30 is 12.5 nm or more and 30 nm or less. Furthermore, if Ds is 15 nm or more and 25 nm or less, a Tp×Rs of 76% or more can be obtained, which is more preferable.

[0187] Regarding the contrast CR (CR=Tp / Ts) of transmitted light, the side thickness Ds of the reflective film 30 needs to be 10 nm or more, but if Ds is 12.5 nm or more, an excellent contrast CR of 50 or more can be obtained. Furthermore, if Ds is 15 nm or more, a CR of 100 or more can be obtained, which is more preferable.

[0188] 2.11. Uneven Distribution of Reflective Film In addition, in the polarizing element 1 according to this embodiment, the reflective film 30 covering the ridge portions 22 may be unevenly distributed on one side of the ridge portions 22, to form an asymmetric shape in the width direction (X direction) of the ridge portions 22. Specifically, the side thickness Ds or coverage Rc of the reflective film 30 may be changed between one side surface 22b and the other side surface 22b of the ridge portions 22, to cause the reflective film 30 to be unevenly distributed on one side surface 22b of the ridge portions 22. In other words, the reflective film 30 may be thick and widely covering one side surface 22b of the ridge portions 22, and thin and narrowly covering the other side surface 22b.

[0189] When the reflective film 30 is unevenly distributed on one side of the ridge portion 22 in this way, it is preferable that the difference between the transmission axis transmittance Tp(+) of incident light whose incident angle with respect to the polarizing element 1 is +θ (+30° to +60°) and the transmission axis transmittance Tp(-) of incident light whose incident angle is -θ (-30° to -60°) be within 3%. Then, it is preferable to appropriately unevenly distribute the reflective film 30 on one side of the ridge portion 22 by adjusting the thickness Ds and coverage Rc of the reflective film 30 that covers one side 22b and the other side 22b of the ridge portion 22 so that the difference between Tp(+) and Tp(-) is within 3%.

[0190] An incident angle of +θ means that oblique incident light is incident on the ridge portion 22 from a direction tilted toward one side of the X direction (the width direction of the ridge portion 22). On the other hand, an incident angle of −θ means that oblique incident light is incident on the ridge portion 22 from a direction tilted toward the other side of the X direction.

[0191] As described above, when the reflective film 30 is unevenly distributed on one side of the ridge portion 22, it is preferable to keep the difference between Tp(+) and Tp(-) within 3%. This makes it possible to obtain a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and a high contrast CR of transmitted light, even when the reflective film 30 is unevenly distributed on one side of the ridge portion 22.

[0192] Specifically, with regard to transmittance, even when the reflective film 30 is biased to one side, the transmission axis transmittance Tp of obliquely incident light with an incident angle θ of +45° and −45° is 85% or more, thereby achieving high transmittance.

[0193] Furthermore, with regard to reflectivity, even when the reflective film 30 is unevenly distributed on one side, the reflection axis reflectivity Rs of obliquely incident light with an incident angle θ of +45° and −45° is 85% or more, and high reflectivity is obtained.

[0194] Furthermore, with regard to the Tp×Rs characteristics required for a polarizing beam splitter (PBS), even when the reflective film 30 is biased to one side, the Tp×Rs of obliquely incident light with an incident angle θ of 45° is 75% or more, thereby achieving excellent Tp×Rs characteristics.

[0195] Furthermore, regarding the contrast CR of transmitted light (CR=Tp / Ts), excellent contrast CR can be obtained even when the reflective film 30 is unevenly distributed on one side. Furthermore, from the viewpoint of improving contrast, of the thicknesses Ds of the reflective films 30 covering the one side surface 22b and the other side surface 22b of the convex ridge portion 22, the thinner thickness Ds is preferably 5 nm or more (its coverage rate Rc is 22% or more), and more preferably the thinner thickness Ds of the reflective film 30 is 10 nm or more (its coverage rate Rc is 33% or more).

[0196] <2.12. Other Components> The polarizing element 1 according to this embodiment may further include components other than the substrate 10, the grid structure 20, and the reflective film 30 described above.

[0197] For example, as shown in Fig. 7, the polarizing element 1 preferably further includes a protective film 40 formed so as to cover at least the surface of the reflective film 30. In particular, as shown in Fig. 7, the protective film 40 more preferably covers the entire surface of the grid structure 20. That is, the protective film 40 is more preferably formed so as to cover all of the side surfaces 22b of the ridge portions 22 of the grid structure 20, the surface of the base portion 21, and the surface of the reflective film 30. By forming such a protective film 40, the scratch resistance, stain resistance, and waterproof properties of the polarizing element 1 can be further improved.

[0198] Furthermore, it is more preferable that the protective film 40 further includes a water-repellent coating or an oil-repellent coating, which can further improve the stain-proof and waterproof properties of the polarizing element 1.

[0199] The material constituting the protective film 40 is not particularly limited as long as it can improve the scratch resistance, stain resistance, and waterproof properties of the polarizing element 1. Examples of materials constituting the protective film 40 include films made of dielectric materials, more specifically, inorganic oxides and silane-based water-repellent materials. Examples of inorganic oxides include silicon oxide and halide oxide. The silane-based water-repellent material may contain a fluorine-based silane compound such as perfluorodecyltriethoxysilane (FDTS), or a non-fluorine-based silane compound such as octadecyltrichlorosilane (OTS).

[0200] Among these materials, it is more preferable that the protective film 40 contains at least one of an inorganic oxide and a fluorine-based water-repellent material. When the protective film 40 contains an inorganic oxide, the scratch resistance of the polarizing element can be further improved, and when the protective film 40 contains a fluorine-based water-repellent material, the stain resistance and waterproofing properties of the polarizing element can be further improved.

[0201] The protective film 40 may be formed so as to cover at least the surface of the reflective film 30. However, as shown in Fig. 7, it is more preferable that the protective film 40 be formed so as to cover the entire surfaces of the grid structure 20 and the reflective film 30. In this case, for example, as shown in the upper diagram of Fig. 7, the protective film 40 may cover the end face of the grid structure 20 (the end face of the base portion 21). Alternatively, as shown in the lower diagram of Fig. 7, the protective film 40 may not cover the end face of the grid structure 20 (the end face of the base portion 21). Furthermore, as shown in Fig. 8, the protective film 40 may be formed so as to cover the entire polarizing element 1, including the surface of the substrate 10 in addition to the surfaces of the grid structure 20 and the reflective film 30. In this way, by covering the outermost surface of the grid structure 20 or the polarizing element 1 with the protective film 40 made of an inorganic oxide, the thermal resistance R of the entire polarizing element 1 can be further reduced, thereby further improving the heat dissipation properties of the polarizing element 1.

[0202] Furthermore, the polarizing element 1 according to this embodiment preferably includes a heat dissipation member 50 surrounding the periphery of the substrate 10, as shown in Fig. 9. The heat dissipation member 50 can more efficiently dissipate heat transferred from the substrate 10. Here, the heat dissipation member 50 is not particularly limited as long as it has a high heat dissipation effect. The heat dissipation member 50 may be, for example, a heat sink, a heat spreader, a die pad, a heat pipe, a metal cover, a housing, or the like.

[0203] 2.13. Actual Image of Grid Structure Next, with reference to Fig. 10 , an example of an actual fabricated polarizing element 1 according to this embodiment, and an enlarged image thereof taken using a scanning electron microscope (SEM), will be described. Fig. 10A is an SEM image of the grid structure 20 before being coated with the reflective film 30, viewed from an oblique direction. Fig. 10B is an SEM image showing a cross section of the ridge portions 22 of the grid structure 20 before being coated with the reflective film 30. Fig. 10C is an SEM image showing a cross section of the ridge portions 22 of the grid structure 20 coated with the reflective film 30.

[0204] 10A and 10B, the grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and protruding ridge portions 22 protruding from the base portion 21. The plurality of protruding ridge portions 22 are arranged at a substantially equal pitch P. Each protruding ridge portion 22 has a tapered shape that narrows in width as it moves away from the base portion 21. The width W of the top of the protruding ridge portion 22 is Ｔ is the width W of the bottom of the ridge portion 22 Ｂ The pitch P is narrower than the width W of the bottom of the ridge portion 22. Ｂ The height H of the ridge portion 22 is greater than the pitch P. In the example of FIG. 10, P=140 nm, W Ｔ = 10 nm, W Ｂ 10C, a reflective film 30 is formed to cover the tip 22a and both side surfaces 22b of the protruding ridge portion 22. The outer surface of the reflective film 30 is curved and rounded, and bulges out in the width direction of the protruding ridge portion 22.

[0205] 3. Method for Manufacturing Polarizing Element Next, a method for manufacturing the wire grid polarizer 1 according to this embodiment will be described with reference to Fig. 11. Fig. 11 is a process chart showing the method for manufacturing the wire grid polarizer 1 according to this embodiment.

[0206] As described above, the polarizing element 1 according to this embodiment is a hybrid wire-grid polarizing element 1 made of an inorganic material (substrate 10) and an organic material (grid structure 20). A method for manufacturing this hybrid wire-grid polarizing element 1 will be described below.

[0207] As shown in FIG. 11, the method for manufacturing the wire-grid polarizer 1 according to this embodiment includes a grid structure material formation step (S10), a nanoimprinting step (S12), a grid structure formation step (S14), and a reflective film formation step (S16).

[0208] Grid Structure Material Formation Step (S10) First, in S10, a grid structure material 23 made of a transparent organic material (e.g., an ultraviolet-curable resin or a thermosetting resin) is laminated by coating or the like on a substrate 10 made of a transparent inorganic material (e.g., glass). The various materials described above can be used as the inorganic material for the substrate 10. The various materials described above can be used as the organic material for the grid structure 20. Furthermore, the film thickness of the grid structure material 23 can be adjusted appropriately depending on the dimensions of the base portion 21 and the ridge portions 22 of the grid structure 20 formed by nanoimprinting in S20.

[0209] Nanoimprinting Step (S12) and Grid Structure Forming Step (S14) Next, in S12, nanoimprinting is performed on the grid structure material 23, and in S14, a grid structure 20 is formed on the substrate 10. The grid structure 20 is a micro-relief structure in which a base portion 21 provided on the substrate 10 and a plurality of protruding ridge portions 22 protruding from the base portion 21 are integrally formed. The micro-relief structure is a structure having minute protrusions and recesses on the order of, for example, several nanometers to several tens of nanometers.

[0210] In the nanoimprinting step of S12, a master 60 on which a reversed shape of the fine concave-convex shape of the grid structure 20 is formed is used to transfer the fine concave-convex shape of the master 60 to the surface of the grid structure material 23 (S12). As a result, a concave-convex pattern consisting of the base portion 21, the ridge portions 22, and the recesses 24 is formed in the grid structure material 23. Furthermore, in the nanoimprinting step, in addition to the transfer of the concave-convex pattern, the grid structure material 23 is irradiated with energy rays to harden the grid structure material 23 to which the concave-convex pattern has been transferred, thereby forming the grid structure 20 (S14). For example, when the grid structure material 23 is made of an ultraviolet curable resin, ultraviolet rays may be irradiated onto the grid structure material 23 using an ultraviolet irradiation device 66 to harden the ultraviolet curable resin to which the concave-convex pattern has been transferred. Alternatively, when the grid structure material 23 is made of a thermosetting resin, a heating device 68 such as a heater may be used to heat the grid structure material 23 to harden the thermosetting resin to which the concave-convex pattern has been transferred.

[0211] In the above steps S12 and S14, the convex rib portions 22 of the grid structure 20 are formed to have a tapered shape whose width narrows with increasing distance from the base portion 21. The convex rib portions 22 in the example of Fig. 11 are trapezoidal (tapered) in shape, but may have various other tapered shapes as shown in Fig. 3.

[0212] As described above, in this embodiment, the tapered convex ridges 22 are imprinted in the nanoimprinting step S12, so that the master 60 can be easily peeled off from the grid structure material 23, resulting in excellent mold-removal properties. Furthermore, the convex ridges 22 of the grid structure 20 can be accurately molded into a desired shape without losing their shape.

[0213] Reflective Film Forming Step (S16) Next, in S16, a metallic material such as Al or Ag is used to form a reflective film 30 that covers part of the protruding stripes 22 of the grid structure 20. The reflective film 30 is an example of a functional film that imparts a predetermined function to the polarizing element 1. The reflective film 30 is a thin metal film (a grid of thin metal wires) that reflects incident light that is incident on the grid structure 20 of the polarizing element 1.

[0214] In this reflective film forming step S16, the reflective film 30 is formed as follows. That is, the reflective film 30 is formed so that it covers the tip 22a and the upper side of at least one side surface 22b of the convex rib portion 22, but does not cover the lower sides of both side surfaces 22b of the convex rib portion 22 or the base portion 21. Furthermore, the reflective film 30 is formed so that the surface of the reflective film 30 that covers the convex rib portion 22 is rounded and bulges in the width direction of the convex rib portion 22. In addition, the maximum width W of the reflective film 30 that covers the convex rib portion 22 is ＭＡＸ (Maximum grid width W ＭＡＸ ) is the width W of the bottom of the convex ridge portion mentioned above Ｂ (Grid bottom width W Ｂ The reflective film 30 is formed so that the reflectance is equal to or greater than 100 .mu.m.

[0215] 5, for example, sputtering or vapor deposition can be used to form such a reflective film 30. The reflective film 30 is formed by sputtering or vapor depositing a metal material alternately from oblique directions relative to the ridge portions 22 of the grid structure 20. This makes it possible to suitably form the reflective film 30 in a desired shape so as to surround the tops of the ridge portions 22 in a round shape.

[0216] By forming the reflective film 30 in this manner, the convex streak portions 22 of the grid structure 20 and the reflective film 30 have the special tree-like shape described above. As a result, as described above, even when light is incident on the polarizing element 1 from an oblique direction at a relatively large and wide range of incident angles θ (e.g., 30 to 60°), the transmission axis transmittance Tp of P-polarized light contained in the obliquely incident light can be maintained at a high value, and the transmittance of P-polarized light (transmitted light) can be ensured. Therefore, the value of Tp×Rs can be maintained at a high value (e.g., 70% or more), thereby improving the polarization separation characteristics of the polarizing element 1 for obliquely incident light.

[0217] The manufacturing method for the polarizing element 1 according to this embodiment may include, as necessary, a step of forming a protective film 40 that covers the surface of the polarizing element 1 (protective film forming step) after the reflective film forming step S16 shown in Fig. 11. The protective film 40 is preferably formed so as to cover the entire surfaces of the grid structure 20 and the reflective film 30. The various materials described above can be used as the material for the protective film 40.

[0218] The above describes the method for manufacturing the polarizing element 1 according to this embodiment. By going through the above-described steps, it is possible to manufacture a polarizing element 1 that has excellent polarization properties and heat dissipation properties without increasing the manufacturing cost of the polarizing element 1 or making the manufacturing process complicated.

[0219] Here, for comparison with the manufacturing method according to this embodiment, a conventional method for manufacturing a wire grid polarizer will be briefly described with reference to FIG.

[0220] 12, in a conventional method for manufacturing a wire-grid polarizer, first, in order to create a convex grid pattern, a metal film 80 is formed on a substrate 10 (S20). In S20, a reflective film made of a material that reflects light in the used band, such as a metal film 80 made of aluminum, is formed on the substrate 10 made of an inorganic material such as glass by sputtering or vapor deposition.

[0221] Next, a resist mask 70 is patterned on the metal film 80 using photolithography (S22). After that, the metal film 80 is etched using a vacuum dry etching device or the like to form a convex shape made of the metal film 80 (S24). For example, if the etching selectivity between the resist mask 70 and the metal film 80 cannot be obtained at this time, a SiO ２ Then, a resist mask 70 is formed on the metal film 80 by photolithography (S26). ２ A protective film 40 made of a film or the like is formed by CVD or the like, and a water-repellent and oil-repellent coating process is also performed as needed (S28).

[0222] While steps S20 to S28 of the conventional manufacturing method described above show the process for producing a reflective wire-grid polarization element with a basic configuration, a more complex process is required when metal film 80 is a multilayer film. Therefore, it is expected that conventional wire-grid polarization elements produced by the process shown in S20 to S28 of Figure 12 will be expensive to manufacture and will take a long time to manufacture. Furthermore, when mass-producing polarization elements, in order to form minute convex shapes smaller than the wavelength of light, it will be necessary to prepare multiple high-precision, expensive etching devices and photolithography devices according to the production volume, and this is expected to result in even higher capital investment.

[0223] In contrast, the manufacturing method of the polarizing element 1 according to this embodiment (see FIG. 11 ) uses an imprinting technique such as nanoimprinting to form the grid structure 20, and therefore can significantly reduce manufacturing costs, manufacturing time, and capital investment compared to the conventional manufacturing method (see FIG. 12 ).

[0224] In the manufacturing method of the polarizing element 1 according to this embodiment, nanoimprinting is performed on the grid structure material 23 (S12 in FIG. 11 ), but the conditions for nanoimprinting are not particularly limited. For example, as shown in S12 in FIG. 11 , a replica master (which may also be a main mold master) is used as the master 60, and while nanoimprinting is performed, the grid structure material 23 is irradiated with UV light or heated, etc., so that the grid structure material 23 is cured in a state in which the concave-convex pattern is imprinted. Thereafter, the master 60 is released from the cured grid structure material 23. In this way, the grid structure 20 having the base portion 21 and the ridge portions 22 formed thereon can be molded by transfer.

[0225] The master 60 used in the nanoimprint step S12 (FIG. 11) in the manufacturing method for the polarizing element 1 according to this embodiment can be manufactured by photolithography, for example, as shown in Fig. 13. Fig. 13 is a process chart showing the manufacturing method for the master 60 according to this embodiment.

[0226] 13, first, a master metal film 62 is formed on a master substrate 61 (S30), and then a resist mask 70 is formed on the master metal film 62 (S32). Next, the master metal film 62 is etched using the resist mask 70, and grooves 65 corresponding to the ridge portions 22 of the grid structure 20 are formed in the etched master metal film 62 (S34).

[0227] Thereafter, the resist mask 70 is peeled off from the master metal film 62 to obtain the master 60 (S36). The master 60 has a fine uneven structure consisting of a plurality of convex portions 63 and concave grooves 65 formed on the master substrate 61. The fine uneven structure on the surface of the master 60 has an inverted shape of the fine uneven structure on the surface of the grid structure 20 of the polarizing element 1. The concave grooves 65 of the master 60 have an inverted shape of the convex streak portions 22 of the grid structure 20, and the convex portions 63 of the master 60 have an inverted shape of the concave portions 24 between the convex streak portions 22, 22 of the grid structure 20.

[0228] Furthermore, the manufacturing method according to this embodiment may include, as necessary, a step (S38) of forming a release film coat 64 on the surface of the fine concave-convex structure of the master 60. By providing the release film coat 64 on the surface of the master 60, after nanoimprinting is performed on the grid structure material 23 in the nanoimprinting step (S12) shown in Fig. 11, the master 60 can be easily peeled off from the grid structure material 23, and the releasability can be further improved.

[0229] 4. Projection Display Device Next, a projection display device to which the wire-grid polarizer 1 according to this embodiment is applied will be described with reference to FIG.

[0230] The projection display device according to this embodiment includes the above-described wire-grid polarizer 1 according to this embodiment. By including the polarizer 1 in the projection display device according to this embodiment, excellent polarization characteristics, as well as the heat resistance and heat dissipation properties of the polarizer 1 can be achieved.

[0231] Here, a projection display device is a device that projects light toward an object and irradiates the projected light (projection light) onto a display surface (projection surface) of the object, thereby displaying a virtual image such as an image or video. Examples of types of projection display devices include a head-up display device (HUD) and a projector device.

[0232] <4.1. Head-up display device> First, a head-up display device 100 including a wire-grid polarizer 1 according to this embodiment will be described with reference to Fig. 14. Fig. 14 is a schematic diagram showing an example of the head-up display device 100 according to this embodiment.

[0233] 14, the head-up display device 100 according to this embodiment includes the wire-grid polarizer 1 according to this embodiment described above. By including the polarizer 1 in the head-up display device 100, it is possible to improve polarization characteristics, heat resistance, and heat dissipation. Head-up displays incorporating conventional polarizers have poor heat dissipation properties, and are therefore considered to have insufficient heat resistance when considering long-term use and future trends toward higher brightness and larger displays.

[0234] 14 , the head-up display device 100 includes a light source 2, a display element 3 that emits a display image, a reflector 4 that reflects the display image onto a display surface 5, and a cover portion 6 that is provided at an opening of a housing 7. In the head-up display device 100, the arrangement of the polarizing element 1 is not particularly limited. For example, as shown in FIG. 14 , the polarizing element 1 can be arranged between the display element 3 and the reflector 4.

[0235] Here, the head-up display device 100 may be a vehicle head-up display device provided in a vehicle. The vehicle head-up display device displays an image on a semi-transparent plate (corresponding to the "display surface 5") such as a windshield or a combiner of the vehicle. The vehicle head-up display device is, for example, an image display device disposed on the dashboard of the vehicle, projects image light onto the windshield (display surface 5), and displays driving information as a virtual image.

[0236] The head-up display device 100 is configured to emit a display image from below toward the windshield surface (display surface 5). Therefore, sunlight may enter in a direction opposite to the emission direction of the display image and be incident on the display element 3. The head-up display device 100 according to this embodiment is provided with a reflector 4 for reflecting and enlarging the display image in order to meet the demand for compactness and to enlarge the display image. In such cases, in conventional head-up display devices, sunlight incident on the reflector from outside is concentrated near the display element, which may cause heat to deteriorate or malfunction the display element.

[0237] In contrast, the head-up display device 100 according to this embodiment is provided with the hybrid polarizing element 1, which has excellent heat dissipation and heat resistance properties as described above, in order to prevent sunlight from entering the display element 3. This polarizing element 1 can stably exhibit its polarization function even at high temperatures, for example, around 200°C. Therefore, even in a high-temperature environment, such as the inside of a car in summer, sunlight that has entered the reflector 4 from the outside can be blocked by the polarizing element 1, preventing it from reaching the display element 3, thereby suppressing deterioration and failure of the display element 3.

[0238] Note that the components of the head-up display device 100 shown in Figure 14 are examples of basic components, and the components of the projection display device are not limited to the example in Figure 14, and other components may be included as appropriate depending on the required performance, etc.

[0239] Furthermore, by using the polarizing element 1 as a pre-polarizing plate disposed in front of the display element 3, the polarizing element 1 can transmit the display image emitted from the display element 3 while suppressing the incidence of sunlight on the display element 3. Therefore, the heat resistance and durability of the head-up display device 100 can be further improved.

[0240] In addition, the arrangement of the wire grid polarizer in the projection display device is not limited to the example of the arrangement of the polarizer 1 in the head-up display device 100 shown in Fig. 14, and can be appropriately selected and changed depending on the configuration of the projection display device, the required performance, etc. For example, although not shown, the polarizer 1 can be arranged between the display element 3 and the light source 2. Also, although not shown, the polarizer 1 can be incorporated into the reflector 4. Furthermore, the cover portion 6 provided in the head-up display device 100 shown in Fig. 14 can also be composed of the polarizer 1.

[0241] Although not shown, a heat dissipation member 50 (see FIG. 9 ) may be provided around the polarizing element 1 installed in the head-up display device 100. The heat dissipation member 50 can further improve the heat dissipation properties of the polarizing element 1, thereby further improving the polarization characteristics and heat resistance of the polarizing element 1.

[0242] 15 to 17, a projection display device that uses the reflective wire-grid polarizer 1 according to this embodiment as a polarization beam splitter 230 will be described. Below, we will first comprehensively describe matters common to the three specific examples of projection display devices 200A, 200B, and 200C (hereinafter sometimes collectively referred to as "projection display device 200") shown in FIGS. 15 to 17. Then, we will individually describe each of the specific examples shown in FIGS. 15 to 17.

[0243] 15 to 17, the projection display device 200 includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250. A phase difference compensator (not shown) may be installed between the polarizing beam splitter 230 and the reflective liquid crystal display element 240.

[0244] Light source 210 may be a point light source having one light-emitting element, or may be a light source having multiple light-emitting elements such as LEDs. Furthermore, the light emitted from light source 210 may be parallel light or diffused light. Therefore, the light from light source 210 may be incident on polarizing beam splitter 230 (reflective wire-grid polarizer) at an incident angle θ within a predetermined range (e.g., a range of 45°±15°) centered around 45°.

[0245] The PS converter 220 is a polarization conversion element for converting the light from the light source 210 into a specific polarization (for example, P polarization or S polarization). The PS converter 220 may convert the light from the light source 210 into either P polarization or S polarization.

[0246] Polarizing beam splitter 230 is configured with a reflective wire-grid polarizer. A reflective wire-grid polarizer is an example of the wire-grid polarizer 1 according to this embodiment. Polarizing beam splitter 230 is disposed so that light from light source 210 is incident at an incident angle θ within a predetermined range including 45°. This predetermined range of incident angle θ is, for example, the above-mentioned 45°±15°, i.e., not less than 30° and not more than 60°.

[0247] 15 to 17, for example, the polarizing beam splitter 230 is disposed at an angle of 45° with respect to the incident direction of the incident light so that the incident light from the light source 210 is incident on the polarizing beam splitter 230 mainly at an incident angle θ of 45°. Also, the polarizing beam splitter 230 is disposed at an angle of 45° with respect to the reflective liquid crystal display element 240 so that the incident light from the reflective liquid crystal display element 240 is incident on the polarizing beam splitter 230 mainly at an incident angle θ of 45°.

[0248] The polarizing beam splitter 230 separates the incident light into a first polarized light (S polarized light) and a second polarized light (P polarized light). For example, the polarizing beam splitter 230 may separate the S polarized light and the P polarized light by reflecting the first polarized light (S polarized light) of the incident light and transmitting the second polarized light (P polarized light). Conversely, the polarizing beam splitter 230 may separate the S polarized light and the P polarized light by reflecting the second polarized light (P polarized light) of the incident light and transmitting the first polarized light (S polarized light).

[0249] When the polarizing beam splitter 230 is to reflect a desired polarized light, the polarizing beam splitter 230 is disposed so that light containing the polarized light to be reflected is incident on the surface of the polarizing beam splitter 230 (i.e., the uneven surface on the side of the polarizing element 1 on which the grid structure 20 is formed). For example, as shown in FIG. 15 , when the polarizing beam splitter 230 is to reflect S-polarized light incident from the PS converter 220, the surface of the polarizing beam splitter 230 can be directed toward the PS converter 220 that emits the S-polarized light. On the other hand, as shown in FIG. 16 , when the polarizing beam splitter 230 is to reflect S-polarized light incident from the reflective liquid crystal display element 240, the surface of the polarizing beam splitter 230 can be directed toward the reflective liquid crystal display element 240 that emits the S-polarized light.

[0250] The reflective liquid crystal display element 240 is a display element that reflects incident light and emits light that represents a display image. As shown in Figures 15 and 17, the reflective liquid crystal display element 240 may be arranged so that the first polarized light (S-polarized light) reflected by the polarizing beam splitter 230 is incident on the surface of the reflective liquid crystal display element 240. Alternatively, as shown in Figure 16, the reflective liquid crystal display element 240 may be arranged so that the second polarized light (P-polarized light) transmitted through the polarizing beam splitter 230 is incident on the surface of the reflective liquid crystal display element 240.

[0251] 15 and 17, the reflective liquid crystal display element 240 reflects and modulates the incident first polarized light (S polarized light) and emits the second polarized light (P polarized light) that represents the display image. However, without being limited to such an example, as shown in FIG. 16, the reflective liquid crystal display element 240 may reflect and modulate the incident second polarized light (P polarized light) and emit the first polarized light (S polarized light) that represents the display image.

[0252] The lens 250 magnifies the light representing the display image emitted from the reflective liquid crystal display element 240 and outputs it to the outside. The lens 250 is arranged so that the light representing the display image emitted from the reflective liquid crystal display element 240 is incident through the polarizing beam splitter 230. For example, as shown in FIGS. 15 and 17 , the lens 250 may be arranged so that the second polarized light (P polarized light) reflected and modulated by the reflective liquid crystal display element 240 passes through the polarizing beam splitter 230 and enters the lens 250. Alternatively, as shown in FIG. 16 , the lens 250 may be arranged so that the first polarized light (S polarized light) reflected and modulated by the reflective liquid crystal display element 240 is reflected by the polarizing beam splitter 230 and enters the lens 250.

[0253] As described above, the projection display device 200 according to this embodiment uses the wire-grid polarizer 1 according to this embodiment described above as the polarizing beam splitter 230. Therefore, the polarizing beam splitter 230 has excellent reflectivity for S-polarized light, excellent transmittance for P-polarized light, and excellent Tp×Rs characteristics for obliquely incident light with a relatively large and wide range of incident angles θ (for example, 30 to 60°), and is excellent in the ability to separate obliquely incident light into P-polarized light and S-polarized light.

[0254] Next, specific examples of the projection display devices 200A, 200B, and 200C shown in FIGS. 15 to 17 will be described individually.

[0255] As shown in FIG. 15, a projection display device 200A according to a first specific example of this embodiment includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250.

[0256] The light emitted from the light source 210 is unpolarized and contains equal proportions of P-polarized and S-polarized components. Therefore, if the polarizing beam splitter 230, which is made of the polarizing element 1, selects and extracts only one polarized light, the amount of light will be reduced by approximately half. Therefore, the PS converter 220 converts the light emitted from the light source 210 into either a first polarized light (S-polarized) or a second polarized light (P-polarized). This suppresses the reduction in the amount of polarized light extracted by the polarizing beam splitter 230, thereby improving light utilization efficiency. For example, the PS converter 220 shown in FIG. 15 converts the light from the light source 210 into a first polarized light (S-polarized).

[0257] The light converted into S-polarized light by PS converter 220 is incident on polarizing beam splitter 230, which is tilted at an angle of approximately 45°. Polarizing beam splitter 230 reflects the first polarized light (S-polarized light) and emits it toward reflective liquid crystal display element 240 at an emission angle of 45°. Reflective liquid crystal display element 240 modulates and reflects the first polarized light (S-polarized light) to generate second polarized light (P-polarized light) that represents a display image, and emits this second polarized light (P-polarized light) toward polarizing beam splitter 230. This second polarized light (P-polarized light) passes through polarizing beam splitter 230 and is magnified by lens 250, after which it is projected onto a display surface (not shown), and the display image is displayed.

[0258] The projection display device 200A having the above configuration includes a reflective wire-grid polarizer made of the wire-grid polarizer 1 according to this embodiment as the polarization beam splitter 230. This improves the polarization separation characteristics of the polarization beam splitter 230 for obliquely incident light and light incident at a wide incidence angle θ, and also improves the heat dissipation and heat resistance of the polarization beam splitter 230 and the projection display device 200A.

[0259] In contrast, projection display devices (not shown) that use conventional polarizing elements as polarizing beam splitters have poor heat dissipation properties. Therefore, their heat resistance is considered insufficient from the standpoints of long-term use, high brightness, and enlarged display. Furthermore, the incident angle θ of light entering a polarizing beam splitter is not limited to 45°, but can be any angle within a predetermined range (e.g., approximately 45°±15°) centered on 45°. Even when obliquely incident light with a large and wide range of incident angles θ is incident on a polarizing beam splitter, the polarizing beam splitter must be able to effectively separate the obliquely incident light into S-polarized and P-polarized light regardless of the incident angle θ. However, polarizing beam splitters using conventional polarizing elements have poor polarization separation characteristics for the obliquely incident light, resulting in poor light utilization efficiency and adverse effects on the image quality of the displayed image, such as uneven brightness.

[0260] In this regard, the polarizing beam splitter 230 of the projection display device 200A according to the first specific example of this embodiment has excellent polarization separation characteristics for obliquely incident light with a large and wide range of incident angles θ, as described above. Therefore, the projection display device 200A can improve the light utilization efficiency and reduce brightness unevenness, thereby improving the quality of the displayed image.

[0261] Furthermore, the projection display device is not limited to the example of the projection display device 200A shown in Figure 15 above, and the components and arrangement of the projection display device can be changed as appropriate, for example, to the projection display device 200B shown in Figure 16 or the projection display device 200C shown in Figure 17.

[0262] As shown in FIG. 16, a projection display device 200B according to a second specific example of this embodiment includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250.

[0263] In the projection display device 200B, the PS converter 220 converts light from the light source 210 into second polarized light (P polarized light). The light converted into P polarized light by the PS converter 220 passes through a polarizing beam splitter 230 tilted at an angle of approximately 45° and enters a reflective liquid crystal display element 240. The reflective liquid crystal display element 240 modulates and reflects the second polarized light (P polarized light) to generate first polarized light (S polarized light) that represents a display image, and emits the first polarized light (S polarized light) toward the polarizing beam splitter 230. The polarizing beam splitter 230 reflects the first polarized light (S polarized light) and emits it toward the lens 250 at an emission angle of 45°. The first polarized light (S polarized light) is magnified by the lens 250 and then projected onto a display surface (not shown), whereupon the display image is displayed.

[0264] The projection display device 200B having the above configuration, like the projection display device 200A described above (see Figure 15), has excellent polarization separation characteristics for obliquely incident light, and can improve the light utilization efficiency and reduce brightness unevenness, thereby improving the image quality of the displayed image.

[0265] Also, as shown in Figure 17, a projection display device 200C according to a third specific example of this embodiment includes a light source 210, a polarizing beam splitter 230, a reflective liquid crystal display element 240, a lens 250, and a light absorber 260, but does not include the above-mentioned PS converter 220.

[0266] In the projection display device 200C, unpolarized light emitted from the light source 210 is directly incident on the polarizing beam splitter 230, which is tilted at an angle of approximately 45°. The polarizing beam splitter 230 reflects the first polarized light (S-polarized) component of the unpolarized light and emits it toward the reflective liquid crystal display element 240 at an emission angle of 45°. On the other hand, the second polarized light (P-polarized) component of the unpolarized light incident on the polarizing beam splitter 230 passes through the polarizing beam splitter 230 and is incident on the light absorber 260. Most of this second polarized light (P-polarized) component is absorbed by the light absorber 260, thereby preventing unwanted second polarized light (P-polarized) from being incident on other optical systems within the projection display device 200C.

[0267] The reflective liquid crystal display element 240 modulates and reflects the component of the first polarized light (S polarized light) incident from the polarizing beam splitter 230 to generate a second polarized light (P polarized light) that represents a display image, and emits the second polarized light (P polarized light) toward the polarizing beam splitter 230. The second polarized light (P polarized light) passes through the polarizing beam splitter 230 and is magnified by the lens 250, and then projected onto a display surface (not shown), whereby the display image is displayed.

[0268] In the projection display device 200C having the above configuration, the PS converter 220 is not installed, and therefore the second polarized light (P polarized light) component of the unpolarized light emitted from the light source 210 is absorbed by the light absorber 260 and is not used to display the display image. This reduces the amount of light in the display image by approximately half. However, this has the advantage that the cost and installation space required for the PS converter 220 can be reduced and the number of parts in the projection display device 200C can be reduced, thereby reducing the cost of the projection display device 200C and making the projection display device 200C more compact.

[0269] The foregoing has described a specific example of the projection display device 200 that uses the reflective wire-grid polarizer 1 according to this embodiment as the polarizing beam splitter 230. Note that the projection display device is not limited to the specific examples of the projection display device 200 shown in Figures 15 to 17, and the components and arrangement of the projection display device may be changed as appropriate, or other components may be provided as appropriate, depending on the required performance, etc.

[0270] 5. Vehicle Next, a vehicle equipped with the image display device according to this embodiment will be described.

[0271] A vehicle (not shown) according to this embodiment is equipped with a projection display device having the wire-grid polarizer 1 according to this embodiment described above. The vehicle may be any of a variety of automobiles, such as passenger cars, light vehicles, buses, trucks, racing cars, construction vehicles, and other large vehicles, as long as it is capable of installing a projection display device. In addition, the vehicle may also be any of a variety of vehicles, such as motorcycles, trains, linear motor cars, and attraction vehicles.

[0272] The vehicle according to this embodiment can project and display a display image on a display surface (for example, the display surface 5 shown in FIG. 14 ) provided in the vehicle using the polarizing element 1 and the projection display device. The display surface is preferably a semi-transparent plate such as the vehicle's windshield, side window, rear window, or combiner. However, the display surface is not limited to this example and may be the surface of any object onto which a display image can be projected, such as various parts, components, or on-board equipment provided in the vehicle.

[0273] The projection display device provided in the vehicle according to this embodiment is, for example, the head-up display device 100 shown in Fig. 14 or the projection display device 200 having the polarizing beam splitter 130 shown in Figs. 15 to 17. However, the projection display device is not limited to these examples, and may be any of various image display devices, such as a projector mounted on a vehicle, a car navigation device, or a terminal device with an image display function, as long as it is a device capable of projecting or displaying an image.

[0274] As described above, in the head-up display device 100, as shown in FIG. 14 , sunlight may enter the head-up display device 100 from outside the vehicle through the windshield (display surface 5). The heat of this sunlight may cause deterioration or failure of the display element 3. Therefore, in order to prevent sunlight from entering the display element 3, the hybrid wire-grid polarizer 1 described above is provided in the head-up display device 100. This polarizer 1 has a hybrid structure with high thermal conductivity, and therefore has excellent heat dissipation and heat resistance. Therefore, the polarizer 1 can block sunlight entering the head-up display device 100 from outside, preventing it from reaching the display element 3, thereby preventing failure or damage to the display element 3. Furthermore, the polarizer 1 has excellent heat dissipation and heat resistance, and therefore can prevent damage to the polarizer 1 itself.

[0275] 15 to 17 is installed in a vehicle, the polarizing element 1 used as the polarizing beam splitter 230 can block sunlight from outside, thereby preventing breakdowns and damage to other components such as the reflective liquid crystal display element 240. Furthermore, damage to the polarizing element 1 itself, which has excellent heat dissipation and heat resistance, can also be prevented.

[0276] As described above, the projection display device installed in the vehicle of this embodiment can obtain excellent polarization characteristics (such as sunlight blocking performance and polarization separation characteristics) due to the polarizing element 1, and can also achieve excellent heat resistance and durability of the projection display device.

[0277] The vehicle is not particularly limited as long as it is equipped with the above-mentioned projection display device and polarizing element, and other conditions can be set and changed as appropriate depending on the performance required of the vehicle.

[0278] 6. Organic Material (Photo-Curable Acrylic Resin for Imprinting) Constituting the Grid Structure Next, the organic material (photo-curable acrylic resin for imprinting) constituting the grid structure 20 according to this embodiment will be described.

[0279] The photocurable acrylic resin for imprints according to this embodiment is an uncured resin composition. The photocurable acrylic resin for imprints according to this embodiment is composed of a photopolymerizable component and a photopolymerization initiator. The photopolymerizable component according to this embodiment is one type of the above-mentioned acrylic polymerizable compound. The photopolymerization initiator according to this embodiment is a substance for polymerizing the photopolymerizable component, and corresponds to the above-mentioned photocuring initiator.

[0280] <6.1. Composition of Photopolymerizable Component> Next, the composition of the photopolymerizable component of the photocurable acrylic resin for imprints according to this embodiment will be described. The photopolymerizable component according to this embodiment contains at least resin (A) and resin (B). Furthermore, the photopolymerizable component according to this embodiment may contain resin (C) in addition to resin (A) and resin (B). Furthermore, the photopolymerizable component according to this embodiment may be composed of only resin (A) and resin (B), or may be composed of only resin (A), resin (B), and resin (C). Resins (A) to (C) will be described below.

[0281] Resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, such as one or both of phenylethyl acrylate and benzyl acrylate.

[0282] Resin (A) has a viscosity of, for example, 2.0 mPa·s or more and 10.0 mPa·s or less at 25°C. When resin (A) is phenyl ethyl acrylate, resin (A) has a viscosity of 9.0 mPa·s at 25°C. When resin (A) is benzyl acrylate, resin (A) has a viscosity of 2.2 mPa·s at 25°C. The viscosity is the viscosity of a liquid measured using a rotational viscometer and a vibration viscometer in accordance with JIS Z8803. The viscosity is measured using, for example, a Brookfield viscometer manufactured by Eiko Seiki Co., Ltd. using a cone plate.

[0283] Resin (B) is a bifunctional compound. Resin (B) is, for example, a bifunctional acrylate monomer. Resin (B) is, for example, one or more selected from the group consisting of (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate, (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate, and 1,6-hexanediol diacrylate. Resin (B) preferably contains one of 1,6-hexanediol diacrylate, (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate, and (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate.

[0284] (Octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate is a bifunctional acrylate monomer represented by the following chemical formula (I): As (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate, for example, a product named "KAYARAD R-684" manufactured by Nippon Kayaku Co., Ltd. can be used. /

[0285] Bis(2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene acrylate is a bifunctional acrylate monomer represented by the following chemical formula (II): Bis(2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene acrylate can be, for example, available from Nippon Kayaku Co., Ltd. under the trade name "KAYARAD R-604." /

[0286] 1,6-Hexanediol diacrylate is a bifunctional acrylate monomer represented by the following chemical formula (III). For example, 1,6-hexanediol diacrylate manufactured by Shin-Nakamura Chemical Co., Ltd. under the product name "A-HD-N" can be used. CH ２ = CHCOO(CH ２ ) ６ OOCCH=CH ２ ... (III)

[0287] Resin (B) has, for example, a viscosity of 5.0 mPa·s or more and 500 mPa·s or less at 25°C. When resin (B) is (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate, resin (B) has a viscosity of 100 mPa·s or more and 250 mPa·s or less at 25°C. When resin (B) is bis(2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene acrylate, resin (B) has a viscosity of 200 mPa·s or more and 400 mPa·s or less at 25°C. When resin (B) is 1,6-hexanediol diacrylate, resin (B) has a viscosity of 6.5 mPa·s at 25°C.

[0288] Resin (C) is, for example, an acrylate monomer having three or more functional groups. Resin (C) contains, for example, one or both of dipentaerythritol hexaacrylate and tris-(2-acryloxyethyl) isocyanurate. For example, dipentaerythritol hexaacrylate may be available under the trade name "KAYARAD DPHA" manufactured by Nippon Kayaku Co., Ltd. For example, tris-(2-acryloxyethyl) isocyanurate may be available under the trade name "A-9300S" manufactured by Shin-Nakamura Chemical Co., Ltd.

[0289] Resin (C) has, for example, a viscosity of 1,000 mPa·s or more and 12,000 mPa·s or less at 25° C. When resin (C) is dipentaerythritol hexaacrylate, resin (C) has a viscosity of 5,000 mPa·s or more and 10,000 mPa·s or less at 25° C. When resin (C) is tris-(2-acryloxyethyl)isocyanurate, resin (C) has a viscosity of 1,000 mPa·s at 50° C.

[0290] <6.2. Content of each resin in the entire photopolymerization component> Next, the content of each resin in the entire photopolymerization component according to this embodiment will be described. In this embodiment, the content of resin (A) relative to the entire photopolymerization component is 20% by mass or more, preferably 23% by mass or more. The content of resin (A) relative to the entire photopolymerization component is 42% by mass or less, preferably 35% by mass or less, and more preferably 30% by mass or less. The content of resin (A) relative to the entire photopolymerization component is 20% by mass or more and 42% by mass or less, preferably 20% by mass or more and 35% by mass or less, and more preferably 20% by mass or more and 30% by mass or less.

[0291] In this embodiment, the content of resin (B) relative to the total photopolymerization components is 43% by mass or more, preferably 45% by mass or more. The content of resin (B) relative to the total photopolymerization components is 66% by mass or less, preferably 60% by mass or less. The content of resin (B) relative to the total photopolymerization components is 43% by mass or more and 66% by mass or less, preferably 45% by mass or more and 66% by mass or less, more preferably 45% by mass or more and 60% by mass or less.

[0292] In this embodiment, the content of resin (C) relative to the total photopolymerization components is, for example, 1% by mass or more, preferably 10% by mass or more, and more preferably 15% by mass or more. The content of resin (C) relative to the total photopolymerization components is, for example, 30% by mass or less, preferably 20% by mass or less. The content of resin (C) relative to the total photopolymerization components is, for example, 1% by mass or more and 30% by mass or less, and preferably 10% by mass or more and 20% by mass or less.

[0293] In this embodiment, the total content of resin (A) and resin (B) relative to the total photopolymerization components is, for example, 70% by mass or more, preferably 80% by mass or more, and more preferably 85% by mass. The total content of resin (A) and resin (B) relative to the total photopolymerization components is, for example, 99% by mass or less, preferably 90% by mass or less. The total content of resin (A) and resin (B) relative to the total photopolymerization components is, for example, 70% by mass or more and 99% by mass or less, and preferably 80% by mass or more and 90% by mass or less.

[0294] In this embodiment, the total content of resin (A) and resin (C) relative to the total photopolymerization components is, for example, 34% by mass or more, preferably 40% by mass or more. The total content of resin (A) and resin (C) relative to the total photopolymerization components is, for example, 57% by mass or less, preferably 54% by mass or less. The total content of resin (A) and resin (C) relative to the total photopolymerization components is, for example, 34% by mass or more and 57% by mass or less, preferably 40% by mass or more and 54% by mass or less.

[0295] In this embodiment, the total content of resin (B) and resin (C) relative to the total photopolymerization components is, for example, 58% by mass or more, preferably 67% by mass or more, and more preferably 70% by mass or more. The total content of resin (B) and resin (C) relative to the total photopolymerization components is, for example, 80% by mass or less, preferably 77% by mass or less. The total content of resin (B) and resin (C) relative to the total photopolymerization components is, for example, 58% by mass or more and 80% by mass or less, and preferably 67% by mass or more and 77% by mass or less.

[0296] In this embodiment, the content of the resin having a viscosity of 20 mPa·s or less at 25°C relative to the total photopolymerization components is, for example, 43% by mass or more, preferably 46% by mass or more, and more preferably 50% by mass or more. The content of the resin having a viscosity of 20 mPa·s or less at 25°C relative to the total photopolymerization components is, for example, 84% by mass or less, preferably 66% by mass or less, and more preferably 60% by mass or less. The content of the resin having a viscosity of 20 mPa·s or less at 25°C relative to the total photopolymerization components is 43% by mass or more and 84% by mass or less, preferably 46% by mass or more and 66% by mass or less, and more preferably 50% by mass or more and 60% by mass or less.

[0297] <6.3. Photopolymerization initiator> Next, the photopolymerization initiator according to this embodiment will be described. The photopolymerization initiator according to this embodiment is, for example, an acylphosphine oxide-based photopolymerization initiator or an alkylphenone-based photopolymerization initiator. As the photopolymerization initiator, for example, a product name "Irgacure 819" manufactured by IGM Resins B.V. can be used.

[0298] In the photocurable acrylic resin for imprinting, when the content of all photopolymerizable components is taken as 100% by mass, the content of the photopolymerization initiator is preferably 0.5% by mass or more, and more preferably 1% by mass or more. In the photocurable acrylic resin for imprinting, when the content of all photopolymerizable components is taken as 100% by mass, the content of the photopolymerization initiator is preferably 3% by mass or less. In the photocurable acrylic resin for imprinting, when the content of all photopolymerizable components is taken as 100% by mass, the content of the photopolymerization initiator is preferably 0.5% by mass or more and 3% by mass or less, and more preferably 1% by mass or more and 3% by mass or less.

[0299] <6.4. Viscosity of Photocurable Acrylic Resin for Imprinting> Next, the viscosity of the photocurable acrylic resin for imprinting according to this embodiment will be described. Due to the relationship between the contents of resin (A), resin (B), and resin (C) shown in 6.2 above, the viscosity of the photocurable acrylic resin for imprinting at 25°C is, for example, 90 mPa·s or less, preferably 70 mPa·s or less, and more preferably 30 Pa·s or less. The viscosity of the photocurable acrylic resin for imprinting at 25°C is, for example, 10 mPa·s or more. The viscosity of the photocurable acrylic resin for imprinting at 25°C is, for example, 10 mPa·s or more and 90 mPa·s or less, preferably 10 mPa·s or more and 70 mPa·s or less, and more preferably 10 mPa·s or more and 30 Pa·s or less.

[0300] 6.5. YI Value of Cured Product of Photocurable Acrylic Resin for Imprints Next, the YI (Yellow Index) value of the cured product obtained by irradiating the photocurable acrylic resin for imprints according to this embodiment with light (e.g., ultraviolet light) will be described. The YI value is calculated based on JIS K 7373:2006, "Plastics - Determination of yellowness index and change of yellowness index." The YI value is calculated, for example, from the results of measurement using a UV-Visible-Near-Infrared Spectrophotometer V-770 manufactured by JASCO Corporation. Specifically, the transmittance of the cured product for light in the wavelength range of 380 nm to 800 nm at 0° incidence is measured using a D65 light source in the UV-Visible-Near-Infrared Spectrophotometer V-770. Then, hue calculations are performed using software on the measurement results to calculate X, Y, and Z in the XYZ color system. The YI value is calculated by substituting the calculated X, Y, and Z values ​​of the XYZ color system into the following formula (3) shown in JIS K 7373:2006: YI=100×(1.2985X−1.1335Z) / Y (3)

[0301] After a cured product of the photocurable acrylic resin for imprints according to this embodiment is maintained at 150°C for 500 hours, the YI value of the cured product is preferably 0 or greater. After a cured product of the photocurable acrylic resin for imprints is maintained at 150°C for 500 hours, the YI value of the cured product may be 3.0 or less, preferably 2.5 or less, more preferably 2.0 or less, and even more preferably 1.4 or less. After a cured product of the photocurable acrylic resin for imprints is maintained at 150°C for 500 hours, the YI value of the cured product may be 0.0 or greater but 3.0 or less, preferably 0.0 or greater but 2.5 or less, more preferably 0.0 or greater but 2.0 or less, and even more preferably 0.0 or greater but 1.4 or less.

[0302] <6.6. Average transmittance of cured product of photocurable acrylic resin for imprinting> Next, the average transmittance of light of the cured product of the photocurable acrylic resin for imprinting according to this embodiment will be described. The average transmittance is calculated by measuring the transmittance at 1 nm intervals in the wavelength range of 430 nm or more and 680 nm or less, and simply averaging the obtained 251 pieces of measurement data. The transmittance is measured, for example, using a UV-Visible-Near-Infrared Spectrophotometer V-770 manufactured by JASCO Corporation.

[0303] After a cured product of the photocurable acrylic resin for imprints according to this embodiment is maintained at 150°C for 500 hours, the cured product may have an average transmittance of 91% or more, preferably 91.5% or more, and more preferably 92% or more for light in a wavelength region of 430 nm or more and 680 nm or less. After a cured product of the photocurable acrylic resin for imprints is maintained at 150°C for 500 hours, the cured product may have an average transmittance of 93% or less for light in a wavelength region of 430 nm or more and 680 nm or less. After a cured product of the photocurable acrylic resin for imprints is maintained at 150°C for 500 hours, the cured product may have an average transmittance of 91% or more and 93% or less for light in a wavelength region of 430 nm or more and 680 nm or less.

[0304] Furthermore, the difference in average transmittance of the cured product of the photocurable acrylic resin for imprints according to this embodiment for light in a wavelength region of 430 nm or more and 680 nm or less before and after holding at 150° C. for 500 hours (|average transmittance before holding−average transmittance after holding|) may be −0.2% or more. The difference in average transmittance of the cured product of the photocurable acrylic resin for imprints for light in a wavelength region of 430 nm or more and 680 nm or less before and after holding at 150° C. for 500 hours (|average transmittance before holding−average transmittance after holding|) may be 0.6% or less, preferably 0.5% or less, and more preferably 0.2% or less. The difference in average transmittance of a cured product of the photocurable acrylic resin for imprints for light in a wavelength region of 430 nm or more and 680 nm or less before and after holding the cured product at 150°C for 500 hours (|average transmittance before holding−average transmittance after holding|) may be −0.2% or more and 0.6% or less, preferably −0.2% or more and 0.5% or less, and more preferably −0.2% or more and 0.2% or less.

[0305] After a cured product of the photocurable acrylic resin for imprinting according to this embodiment is maintained at 150°C for 500 hours, the cured product may have an average transmittance of 90% or more, and preferably 91% or more, for light in a wavelength region of 430 nm or more and 510 nm or less. After a cured product of the photocurable acrylic resin for imprinting according to this embodiment is maintained at 150°C for 500 hours, the cured product may have an average transmittance of 92% or less, for light in a wavelength region of 430 nm or more and 510 nm or less. After a cured product of the photocurable acrylic resin for imprinting according to this embodiment is maintained at 150°C for 500 hours, the cured product may have an average transmittance of 90% or more and 92% or less, and preferably 91% or more and 92% or less, for light in a wavelength region of 430 nm or more and 510 nm or less.

[0306] Furthermore, the difference in average transmittance of the cured product of the photocurable acrylic resin for imprints according to this embodiment for light in a wavelength region of 430 nm or more and 510 nm or less before and after holding at 150° C. for 500 hours (|average transmittance before holding−average transmittance after holding|) may be 0.0% or more. The difference in average transmittance of the cured product of the photocurable acrylic resin for imprints for light in a wavelength region of 430 nm or more and 510 nm or less before and after holding at 150° C. for 500 hours (|average transmittance before holding−average transmittance after holding|) may be 1.6% or less, preferably 1.1% or less, and more preferably 0.5% or less. The difference in average transmittance of a cured product of the photocurable acrylic resin for imprints to light in a wavelength region of 430 nm or more and 510 nm or less before and after holding the cured product at 150°C for 500 hours (|average transmittance before holding−average transmittance after holding|) may be 0.0% or more and 1.6% or less, preferably 0.0% or more and 1.1% or less, and more preferably 0.0% or more and 0.5% or less.

[0307] 6.7. Storage Modulus of Cured Product of Photocurable Acrylic Resin for Imprinting Next, the storage modulus of the cured product of the photocurable acrylic resin for imprinting will be described. The storage modulus is the component of energy generated by external force and strain that is stored inside an object. In other words, the storage modulus indicates the hardness of the cured product. The higher the storage modulus, the harder the cured product. The storage modulus can be measured, for example, using a product named "DMA7100" manufactured by Hitachi High-Tech Corporation. For example, a sheet of the cured product can be cut into a size of 20 mm length x 3 mm width, and the temperature can be raised at a rate of 5°C / min in a tensile mode at a constant frequency (1 Hz) to measure the storage modulus from 25°C to 300°C.

[0308] The storage modulus of the cured product of the photocurable acrylic resin for imprints according to this embodiment at 30°C is 2.0 × 10 ９ Pa or more, preferably 2.5 × 10 ９ Pa or more, more preferably 3.0 × 10 ９The storage modulus of the cured product of the photocurable acrylic resin for imprints at 30°C is 3.2 × 10 ９ The storage modulus of the cured product of the photocurable acrylic resin for imprints at 30°C may be 2.0 × 10 Pa or less. ９ Pa or more, 3.2×10 ９ Pa or less, and preferably 2.5 × 10 ９ Pa or more, 3.2×10 ９ Pa or less, and more preferably 3.0 × 10 ９ Pa or more, 3.2×10 ９ Pa or less.

[0309] The storage modulus of the cured product of the photocurable acrylic resin for imprints according to this embodiment at 110°C is 1.3 × 10 ８ Pa or more, preferably 1.5 × 10 ８ Pa or more, more preferably 3.0 × 10 ８ Pa or more, and more preferably 5.0 × 10 ８ The storage modulus of the cured product of the photocurable acrylic resin for imprints according to this embodiment at 110°C is 1.1 × 10 ９ The storage modulus of the cured product of the photocurable acrylic resin for imprints according to this embodiment at 110°C may be 1.3 × 10 ８ Pa or more, 1.1×10 ９ Pa or less, and preferably 1.5 × 10 ８ Pa or more, 1.1×10 ９ Pa or less, and more preferably 3.0 × 10 ８ Pa or more, 1.1×10 ９ Pa or less, and more preferably 5.0 × 10 ８ Pa or more, 1.1×10 ９ Pa or less.

[0310] The storage modulus of the cured product of the photocurable acrylic resin for imprints according to this embodiment at 120°C is 1.3 × 10 ８ Pa or more, preferably 3.0 × 10 ８Pa or more, and more preferably 5.0 × 10 ８ The storage modulus of the cured product of the photocurable acrylic resin for imprints at 120°C is 9.1 × 10 ８ The storage modulus of the cured product of the photocurable acrylic resin for imprints at 120°C may be 1.3 × 10 Pa or less. ８ Pa or more, 9.1×10 ８ Pa or less, and preferably 3.0 × 10 ８ Pa or more, 9.1×10 ８ Pa or less, and more preferably 5.0 × 10 ８ Pa or more, 9.1×10 ８ Pa or less.

[0311] The storage modulus of the cured product of the photocurable acrylic resin for imprints according to this embodiment at 130°C is 1.4 × 10 ８ Pa or more, preferably 2.0 × 10 ８ Pa or more, and more preferably 7.0 × 10 ８ The storage modulus of the cured product of the photocurable acrylic resin for imprints at 130°C is 8.0 × 10 ８ The storage modulus of the cured product of the photocurable acrylic resin for imprints at 130°C may be 1.4 × 10 Pa or less. ８ Pa or more, 8.0×10 ８ Pa or less, and preferably 2.0 × 10 ８ Pa or more, 8.0×10 ８ Pa or less, and more preferably 7.0 × 10 ８ Pa or more, 8.0×10 ８ Pa or less.

[0312] 6.8. Glass Transition Temperature Tg of Cured Product of Photocurable Acrylic Resin for Imprinting> Next, the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprinting will be described. The glass transition temperature Tg can be measured using, for example, a "DMA7100" model manufactured by Hitachi High-Tech Corporation. For example, the glass transition temperature Tg can be measured by cutting a sheet of the cured product into a size of 20 mm length x 3 mm width, raising the temperature at a rate of 5°C / min in a tensile mode at a constant frequency (1 Hz), and confirming the maximum value of the loss tangent tanδ from 25°C to 300°C.

[0313] The glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints according to this embodiment may be 58° C. or higher, preferably 80° C. or higher, and more preferably 100° C. or higher. The glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints may be 181° C. or lower. The glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints may be 58° C. or higher and 110° C. or lower, preferably 80° C. or higher and 110° C. or lower, and more preferably 100° C. or higher and 110° C. or lower.

[0314] 6.9. Method for Producing Photocurable Acrylic Resin for Imprints Next, a method for producing the photocurable acrylic resin for imprints according to this embodiment will be described.

[0315] The method for producing a photocurable acrylic resin for imprinting according to this embodiment preferably includes mixing multiple resins contained in the photopolymerizable component and then mixing a powder photopolymerization initiator into the mixed resin of the multiple resins. For example, when the photopolymerizable component includes resin (A) and resin (B), the method for producing a photocurable acrylic resin for imprinting includes mixing resin (A) and resin (B) and mixing the mixed resin of resin (A) and resin (B) with a photopolymerization initiator. When the photopolymerizable component includes resin (A), resin (B), and resin (C), the method for producing a photocurable acrylic resin for imprinting includes mixing resin (A), resin (B), and resin (C) and mixing the mixed resin of resin (A), resin (B), and resin (C) with a photopolymerization initiator.

[0316] Furthermore, when the photopolymerization component contains multiple types of resins, the method for producing a photocurable acrylic resin for imprinting preferably involves mixing the multiple types of resins contained in the photopolymerization component in order of viscosity, starting with the resin with the lowest viscosity, to produce a mixed resin. For example, when the photopolymerization component contains resin (A), resin (B), and resin (C), the method for producing a photocurable acrylic resin for imprinting includes mixing resin (A) and resin (B) to produce a first mixed resin, and mixing resin (C) with the first mixed resin to produce a second mixed resin. It is then preferable to mix a photopolymerization initiator into the second mixed resin.

[0317] The photocurable acrylic resin for imprinting may be produced, for example, using a rotation-revolution mixer.

[0318] 6.10. Effects of Photocurable Acrylic Resin for Imprints As described above, the photocurable acrylic resin for imprints according to this embodiment is a photocurable acrylic resin for imprints containing a photopolymerizable component, the photopolymerizable component containing resin (A) and resin (B), the resin (A) being a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, and the resin (B) being a bifunctional compound, the content of resin (A) relative to all photopolymerizable components is 20% by mass or more and 42% by mass or less, and the content of resin (B) relative to all photopolymerizable components is 43% by mass or more and 66% by mass or less.

[0319] As described above, the photocurable acrylic resin for imprinting according to this embodiment contains resin (A). Resin (A) has one or both of a phenyl group and a benzyl group. Therefore, resin (A) has little steric hindrance and is highly reactive. Therefore, in the photocurable acrylic resin for imprinting according to this embodiment, even when a cured product of the photocurable acrylic resin for imprinting is heated, the terminal aromatic rings interact with each other, thereby suppressing decomposition of the cured product. Therefore, the photocurable acrylic resin for imprinting according to this embodiment can improve the heat resistance of the cured product of the photocurable acrylic resin for imprinting.

[0320] Furthermore, the resin (A) is a monofunctional acrylate monomer. Therefore, the resin (A) can terminate the reaction at the polymer terminal during the polymerization reaction (curing reaction) of the photocurable acrylic resin for imprints. This makes it possible to suppress deterioration from the terminal groups of the cured product (polymer) of the photocurable acrylic resin for imprints.

[0321] The photocurable acrylic resin for imprints according to this embodiment also contains the resin (B), which allows the photocurable acrylic resin for imprints according to this embodiment to have improved heat resistance when cured.

[0322] As described above, in the photocurable acrylic resin for imprints according to this embodiment, the content of resin (A) relative to all photopolymerizable components is 20% by mass or more and 42% by mass or less, and the content of resin (B) relative to all photopolymerizable components is 43% by mass or more and 66% by mass or less, thereby enabling the photocurable acrylic resin for imprints according to this embodiment to achieve both low viscosity and improved heat resistance of the cured product.

[0323] The low viscosity of the photocurable acrylic resin for imprinting according to this embodiment makes it possible to make the thickness (layer thickness) of the photocurable acrylic resin for imprinting uniform when the master 60 is pressed against the photocurable acrylic resin for imprinting (organic material) in the nanoimprinting step S12 ( FIG. 11 ). This makes it possible to make the peeling force applied when peeling the master 60 from the cured photocurable acrylic resin for imprinting uniform across the surface. This prevents the cured photocurable acrylic resin for imprinting from peeling off from the substrate 10. This prevents the cured photocurable acrylic resin for imprinting from remaining on the master 60, allowing the master 60 to be reused repeatedly. Furthermore, because the peeling force can be made uniform across the surface, it is possible to prevent deformation of the fine concave-convex shape transferred to the cured photocurable acrylic resin for imprinting when peeling the master 60. This prevents deterioration of the optical properties of the cured photocurable acrylic resin for imprinting, which is caused by the fine concave-convex shape. Therefore, when the grid structure 20 is manufactured using a cured product of the photocurable acrylic resin for imprinting, it is possible to suppress deterioration in the polarization characteristics of the grid structure 20 .

[0324] Furthermore, the low viscosity of the photocurable acrylic resin for imprinting according to this embodiment improves the ability of the photocurable acrylic resin for imprinting to conform to the fine concave-convex shape of the master 60 when the master 60 is pressed against the photocurable acrylic resin for imprinting in the nanoimprinting step S12. Therefore, in the nanoimprinting step S12, it becomes possible to evenly transfer the fine concave-convex shape of the master 60 onto the layer of the photocurable acrylic resin for imprinting.

[0325] Furthermore, since the photocurable acrylic resin for imprinting according to this embodiment has a low viscosity, it is possible to prevent air bubbles from being mixed into the photocurable acrylic resin for imprinting in the nanoimprinting step S12. This makes it possible to avoid a situation in which the fine concave-convex shape is partially interrupted by air bubbles in the cured product of the photocurable acrylic resin for imprinting. Therefore, when a grid structure 20 is manufactured using the cured product of the photocurable acrylic resin for imprinting, it is possible to prevent breakage of the ridge portions 22 of the grid structure 20.

[0326] The cured product of the photocurable acrylic resin for imprinting according to this embodiment has excellent heat resistance. Therefore, when an optical material (e.g., the grid structure 20 of the wire-grid polarizer 1) is produced using the cured product of the photocurable acrylic resin for imprinting, deterioration of the optical properties of the optical material can be further suppressed even when the optical material is further subjected to a heat treatment such as vapor deposition.

[0327] Furthermore, as described above, the photopolymerizable component may further contain a resin (C), which is an acrylate monomer having three or more functional groups, and the content of the resin (C) relative to the entire photopolymerizable component may be 1% by mass or more and 30% by mass or less.

[0328] This allows the photocurable acrylic resin for imprinting according to this embodiment to have an increased crosslink density during curing, thereby suppressing a decrease in the storage modulus of the cured product of the photocurable acrylic resin for imprinting at high temperatures. Furthermore, as described above, in the photocurable acrylic resin for imprinting according to this embodiment, the content of resin (C) relative to the total photopolymerization components is preferably 1% by mass or more and 30% by mass or less. This further prevents a decrease in the storage modulus of the cured product of the photocurable acrylic resin for imprinting at high temperatures.

[0329] As mentioned above, the resin (A) may be one or both of phenylethyl acrylate and benzyl acrylate.

[0330] This allows the photocurable acrylic resin for imprints according to this embodiment to have improved heat resistance in a cured product of the photocurable acrylic resin for imprints. Furthermore, in this case, the resin (A) has a viscosity of 9.0 mPa s or less at 25° C. This allows the viscosity of the photocurable acrylic resin for imprints according to this embodiment to be further reduced.

[0331] As described above, the resin (B) may be one or more selected from the group consisting of (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate, (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate, and 1,6-hexanediol diacrylate.

[0332] This allows the photocurable acrylic resin for imprints according to this embodiment to have improved heat resistance in the cured product thereof.

[0333] As described above, resin (B) may also contain 1,6-hexanediol diacrylate and one of (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate and (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate.

[0334] This makes it possible to further reduce the viscosity of the photocurable acrylic resin for imprints and further improve the heat resistance of the photocurable acrylic resin for imprints.

[0335] As described above, the resin (C) may contain one or both of dipentaerythritol hexaacrylate and tris-(2-acryloxyethyl)isocyanurate.

[0336] This makes it possible to further suppress the decrease in storage modulus at high temperatures of the cured product of the photocurable acrylic resin for imprints.

[0337] As described above, the viscosity of the photocurable acrylic resin for imprints at 25° C. may be 90 mPa·s or less.

[0338] This makes it possible to make the thickness of the layer of the photo-curable acrylic resin for imprinting more uniform when the master 60 is pressed against the photo-curable acrylic resin for imprinting in the nanoimprinting step S12, thereby improving the ability of the photo-curable acrylic resin for imprinting to conform to the fine uneven shape of the master 60 and further suppressing the inclusion of air bubbles in the photo-curable acrylic resin for imprinting.

[0339] Furthermore, as described above, in the photocurable acrylic resin for imprints according to this embodiment, by setting the content of resin (A) relative to all photopolymerizable components to 20% by mass or more and 42% by mass or less, and the content of resin (B) relative to all photopolymerizable components to 43% by mass or more and 66% by mass or less, the viscosity of the photocurable acrylic resin for imprints at 25°C can be set to 90 mPa s or less.

[0340] For example, the cured product of the photocurable acrylic resin for imprinting according to this embodiment has excellent heat resistance, and after being held at 150° C. for 500 hours, the YI value of the cured product is 3 or less. Therefore, by producing an optical material from the cured product of the photocurable acrylic resin for imprinting, yellowing of the optical material can be suppressed and transparency can be maintained even when the optical material is further subjected to a heat treatment such as vapor deposition.

[0341] As described above, the storage modulus of the cured product of the photocurable acrylic resin for imprints at 30°C is 2.0 × 10 ９ It may be set to Pa or more.

[0342] This makes it possible to more effectively prevent the fine concave-convex shape transferred to the layer of the cured photocurable acrylic resin for imprinting from being deformed when the master 60 is peeled off in the nanoimprinting step S12 ( FIG. 11 ). This makes it possible to further suppress deterioration in the optical properties caused by the fine concave-convex shape of the cured product of the photocurable acrylic resin for imprinting. Therefore, when the grid structure 20 is manufactured using the cured product of the photocurable acrylic resin for imprinting, it is possible to more effectively suppress deterioration in the polarization properties of the grid structure 20.

[0343] Furthermore, for example, the cured product of the photocurable acrylic resin for imprints according to this embodiment has excellent heat resistance, and the storage modulus of the cured product at 120°C is 1.3 × 10 ８ The hardness may be equal to or higher than Pa. Therefore, by producing an optical material from a cured product of the photocurable acrylic resin for imprints, deformation of the optical material can be further suppressed even when the optical material is further subjected to a heat treatment such as vapor deposition. This makes it possible to further suppress deterioration of the optical properties of the optical material.

[0344] Furthermore, for example, the cured product of the photocurable acrylic resin for imprints according to this embodiment has excellent heat resistance, and the storage modulus of the cured product at 130°C is 1.4 × 10 ８ The hardness may be equal to or higher than Pa. Therefore, by producing an optical material from a cured product of the photocurable acrylic resin for imprints, deformation of the optical material can be more suitably suppressed even when the optical material is further subjected to a heat treatment such as vapor deposition. This makes it possible to more suitably suppress deterioration of the optical properties of the optical material.

[0345] Furthermore, for example, the cured product of the photocurable acrylic resin for imprinting according to this embodiment has superior heat resistance, and therefore the cured product has an average transmittance of 91% or more for light in the wavelength region of 430 nm or more and 680 nm or less after being held for 500 hours at 150° C. Therefore, by producing an optical material from the cured product of the photocurable acrylic resin for imprinting, it is possible to maintain a high average transmittance of the optical material for light in the above wavelength region even when the optical material is further subjected to a heat treatment such as vapor deposition.

[0346] Furthermore, for example, the cured product of the photocurable acrylic resin for imprinting according to this embodiment has superior heat resistance, and therefore the cured product has an average transmittance of 90% or more for light in the wavelength region of 430 nm or more and 510 nm or less after being held for 500 hours at 120° C. Therefore, by producing an optical material from the cured product of the photocurable acrylic resin for imprinting, it is possible to maintain a high average transmittance of the optical material for light in the above wavelength region even when the optical material is further subjected to a heat treatment such as vapor deposition.

[0347] As described above, when manufacturing the wire-grid polarizer 1, the reflective film 30 is vapor-deposited on the grid structure 20. The grid structure 20 is heated during the vapor deposition of the reflective film 30. If the grid structure 20 has low heat resistance, the grid structure 20 may be deformed during the vapor deposition of the reflective film 30, resulting in a problem of deterioration in polarization characteristics.

[0348] However, the cured product of the photocurable acrylic resin for imprinting according to this embodiment has superior heat resistance. Therefore, by producing the grid structure 20 using the cured product of the photocurable acrylic resin for imprinting, yellowing and deformation of the grid structure 20 can be further suppressed even when the reflective film 30 is vapor-deposited, and the average transmittance of the grid structure 20 for light in the wavelength range of 430 nm or more and 680 nm or less and for light in the wavelength range of 430 nm or more and 510 nm or less can be maintained at a high level. This makes it possible to more effectively suppress deterioration of the polarization characteristics of the grid structure 20.

[0349] As described above, in the photocurable acrylic resin for imprinting according to this embodiment, the content of the resin (C) relative to the total photopolymerizable components is preferably 1% by mass or more and 30% by mass or less. This can further improve the heat resistance of the photocurable acrylic resin for imprinting according to this embodiment. For example, the storage modulus of the cured product of the photocurable acrylic resin for imprinting at 120°C can be set to 1.3 x 10 ８ The storage modulus of the cured product of the photocurable acrylic resin for imprints at 130°C can be 1.4 × 10 Pa or more. ８ Pa or more.

[0350]

[0046] Furthermore, as described above, in the method for producing a photocurable acrylic resin for imprints according to this embodiment, which comprises a photopolymerizable component and a photopolymerization initiator for polymerizing the photopolymerizable component, the photopolymerizable component includes resin (A) and resin (B), wherein the resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, and the resin (B) is a bifunctional compound, the content of resin (A) relative to the total photopolymerizable components is 20% by mass or more and 42% by mass or less, and the content of resin (B) relative to the total photopolymerizable components is 43% by mass or more and 66% by mass or less, and the method includes mixing resin (A) and resin (B), and mixing the photopolymerization initiator into the mixed resin of resin (A) and resin (B).

[0351] This allows the photopolymerization component and the photopolymerization initiator to be mixed properly, thereby allowing the photopolymerization component to be cured evenly (without unevenness), thereby enabling the heat resistance of the cured product of the photocurable acrylic resin for imprints to be made uniform.

[0352] As described above, in the method for producing a photocurable acrylic resin for imprints containing a photopolymerizable component according to this embodiment, the photopolymerizable component includes resin (A), resin (B), and resin (C), wherein resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, resin (B) is a bifunctional compound, and resin (C) is an acrylate monomer having three or more functional groups; the content of resin (A) relative to all photopolymerizable components is 20% by mass or more and 42% by mass or less, the content of resin (B) relative to all photopolymerizable components is 43% by mass or more and 66% by mass or less, and the content of resin (C) relative to all photopolymerizable components is 1% by mass or more and 30% by mass or less; and the method includes mixing resin (A) and resin (B) to produce a first mixed resin, and mixing resin (C) with the first mixed resin to produce a second mixed resin.

[0353] This allows resin (A), resin (B), and resin (C) to be mixed appropriately, thereby making it possible to uniformize the viscosity of the photocurable acrylic resin for imprints and further uniformize the heat resistance of the cured product of the photocurable acrylic resin for imprints.

[0354] <6.11. Other Components> The photocurable acrylic resin for imprints may contain other components (additives) to the extent that the effects described in the above 6.10 are not impaired. Examples of other components include antioxidants, fluorescent materials, plasticizers, ultraviolet absorbers, antifoaming agents, thixotropic agents, polymerization inhibitors, release agents, and metal oxide particles.

[0355] 7. Inclined Grid Structure Next, a wire-grid polarizer 1 having an inclined grid structure according to a second embodiment of the present invention will be described with reference to Fig. 18 and Fig. 19. Fig. 18 is a cross-sectional view schematically showing the inclined grid structure of the wire-grid polarizer 1 according to the second embodiment. Fig. 19 is a cross-sectional view schematically showing a modified example of the inclined grid structure of the wire-grid polarizer 1 according to the second embodiment.

[0356] 18 and 19 , the grid structure 20 of the wire-grid polarizer 1 (hereinafter sometimes referred to as "polarizer 1") according to the second embodiment has an inclined grid structure. The inclined grid structure is a structure in which the plurality of ridges 22 constituting the grid structure 20 are partially or entirely inclined in the width direction (X direction) of the ridges 22. This inclined grid structure will be described in more detail below.

[0357] Similar to the polarizing element 1 according to the first embodiment (see FIG. 1 , etc.), the polarizing element 1 according to the second embodiment includes a substrate 10 made of an inorganic material, a grid structure 20 made of an organic material, and a reflective film 30 (functional film) made of a metal material. The grid structure 20 is a resin structure integrally formed with a flat base portion 21 provided on the substrate 10 and a plurality of ridge portions 22 protruding from the base portion 21. The ridge portions 22 have a tapered shape such that their width in the X direction narrows with increasing distance from the base portion 21.

[0358] 1 and other figures, in the grid structure 20 according to the first embodiment described above, the ridge portions 22 protrude straight upward along the normal direction (Z direction) to the surface (XY plane) of the substrate 10, and are not inclined in the width direction (X direction) of the ridge portions 22 with respect to the normal direction (Z direction) of the substrate 10. In other words, the central axis of the ridge portions 22 (an axis passing through the center of the width direction (X direction) of the ridge portions 22 and extending in the height direction (Z direction) of the ridge portions 22) is approximately perpendicular to the surface (XY plane) of the substrate 10 and approximately parallel to the normal direction (Z direction) of the substrate 10. The central axis of the ridge portions 22 is an axis passing through the center of the width direction (X direction) of the ridge portions 22 and extending in the height direction (Z direction) of the ridge portions 22.

[0359] 18 and 19 , at least the upper sides of the convex rib portions 22 (at least the portions of the convex rib portions 22 covered with the reflective film 30) are inclined in the width direction (X direction) of the convex rib portions 22 at a predetermined inclination angle α with respect to the normal direction (Z direction) of the substrate 10. That is, the central axis 25 of the inclined portions of the convex rib portions 22 (an axis passing through the center of the width direction of the inclined portions of the convex rib portions 22 and extending in the height direction of the inclined portions of the convex rib portions 22) is inclined at the inclination angle α with respect to the normal direction (Z direction) of the substrate 10, and is also inclined at (90°-α) with respect to the surface (XY plane) of the substrate 10. As a result, the reflective film 30 covering the upper sides of the convex rib portions 22 is also inclined at the inclination angle α with respect to the normal direction (Z direction) of the substrate 10.

[0360] As described above, the grid structure 20 according to the second embodiment has a tilted grid structure in which at least the upper side of the ridges 22 is tilted. This tilted grid structure can impart directivity to the polarizing element 1 with respect to obliquely incident light 31 (e.g., θ = −45°) incident from the tilted side of the ridges 22 (the right side of the X direction in FIGS. 18 and 19 ). In other words, the tilted grid structure allows the reflective film 30 covering the upper side of the tilted ridges 22 to face the obliquely incident light 31 incident from the tilted side. This allows P-polarized light of the obliquely incident light 31 to easily pass through the gaps between the reflective films 30 of the adjacent ridges 22, thereby improving the transmittance Tp of P-polarized light and maintaining a high reflectance Rs of S-polarized light of the obliquely incident light 31 without reducing it. Therefore, it is possible to impart to the polarizing element 1 a directivity that enhances the transmittance (Tp characteristic) and polarization separation characteristic (Tp×Rs characteristic) for the obliquely incident light 31 incident from the oblique direction.

[0361] 18 and 19, for example, the convex streak portions 22 of the grid structure 20 are inclined to the right in the X direction with respect to the normal direction (Z direction). This allows the polarizing element 1 to have excellent transmittance and polarization separation characteristics for obliquely incident light, particularly for obliquely incident light 31 (e.g., θ=−45°) incident from a direction inclined to the right. On the other hand, although not shown, if the convex streak portions 22 of the grid structure 20 are inclined to the left in the X direction with respect to the normal direction (Z direction), the polarizing element 1 will have excellent transmittance and polarization separation characteristics, particularly for obliquely incident light 32 (e.g., θ=+45°) incident from a direction inclined to the left.

[0362] As described above, the inclined grid structure according to the second embodiment can impart to the polarizing element 1 directivity that further enhances the transmittance (transmittance Tp) and polarization separation characteristics (Tp×Rs characteristics) for the obliquely incident light 31, 32 incident from a specific inclined direction. Therefore, it is possible to provide a polarizing element 1 that has even better transmittance (transmittance Tp) and polarization separation characteristics (Tp×Rs characteristics) for the obliquely incident light 31, 32 incident from the specific inclined direction.

[0363] 7.1. Configuration Example of Inclined Grid Structure Next, a configuration example of an inclined grid structure according to the second embodiment will be described with reference to FIGS. 18 and 19. FIG.

[0364] When the inclined grid structure according to the second embodiment is applied to the special tree-shaped grid (a structure combining the grid structure 20 and the reflective film 30) according to the first embodiment described above, a bent inclined grid structure may be used in which only the upper part 22c of the convex stripe portion 22 is partially bent and inclined, as shown in Fig. 18. Alternatively, a bent grid structure in which the entire convex stripe portion 22 is inclined may be used, as shown in Fig. 19.

[0365] 18 , the convex rib portion 22 is bent to the right in the width direction (X direction) of the convex rib portion 22 at a position 27 midway along the height direction (Z direction) of the convex rib portion 22. Therefore, an upper portion 22c of the convex rib portion 22 above the bent position 27 (the portion above the bent position 27) is inclined at an inclination angle α with respect to the normal direction (Z direction) of the surface of the substrate 10 and extends obliquely upward along this inclination direction. On the other hand, a lower portion 22d of the convex rib portion 22 (the portion below the bent position 27) is not inclined with respect to the normal direction (Z direction) and extends straight upward along the Z direction.

[0366] Therefore, the central axis 25 of the upper portion 22c (inclined portion) of the ridge portion 22 is bent to the right in the X direction at an inclination angle α with respect to the central axis 26 of the lower portion 22d (non-inclined portion) of the ridge portion 22. The central axis 25 passes through the center in the width direction of the inclined upper portion 22c of the ridge portion 22 and extends in the height direction of the upper portion 22c. The central axis 26 passes through the center in the width direction (X direction) of the non-inclined lower portion 22d of the ridge portion 22 and extends in the height direction (Z direction) of the lower portion 22d.

[0367] Furthermore, all or part of the upper portion 22 c of the ridge portion 22 is covered with the reflective film 30. Because the upper portion 22 c of the ridge portion 22 is inclined at the inclination angle α as described above, the reflective film 30 covering the upper portion 22 c (inclined portion) of the ridge portion 22 is also inclined to the right in the X direction at the inclination angle α. On the other hand, the lower portion 22 d of the ridge portion 22 is not covered with the reflective film 30.

[0368] As described above, in the tilted grid structure shown in FIG. 18 , the convex streak portion 22 is bent in the X direction halfway along the Z direction, so that only the upper portion 22 c of the convex streak portion 22 is partially tilted. This allows obliquely incident light to be preferably incident on the open portion (the resin portion not covered with the reflective film 30) on the lower side of the side surface 22 b of the convex streak portion 22 of the grid structure 20. Therefore, the bent tilted grid structure shown in FIG. 18 is superior in transmittance and polarization separation characteristics for obliquely incident light compared to the overall tilted grid structure shown in FIG. 19 . Furthermore, the bent tilted grid structure shown in FIG. 18 can expand the preferred range of the tilt angle α compared to the overall tilted grid structure shown in FIG. 19 .

[0369] 19 , the entire ridge portion 22 is inclined in the width direction (X direction) of the ridge portion 22 at an inclination angle α with respect to the normal direction (Z direction) of the substrate 10. That is, the entire ridge portion 22 is inclined from the base of the ridge portion 22 that is joined to the base portion 21, and extends along this inclination direction.

[0370] Therefore, the central axis 25 of the entire ridge portion 22 is inclined at an inclination angle α to the right in the X direction with respect to the normal direction (Z direction) of the substrate 10. As a result, the reflective film 30 covering the upper side of the ridge portion 22 is also inclined at an inclination angle α to the right in the X direction. Note that the central axis 25 shown in Figure 19 passes through the center of the inclined ridge portion 22 in the width direction and is an axis extending in the height direction of the inclined ridge portion 22.

[0371] As described above, in the inclined grid structure shown in Fig. 19, the entire ridge portion 22 is inclined. The inclined grid structure shown in Fig. 19, in which the entire ridge portion 22 is inclined, has a relatively simple shape compared to the bent inclined grid structure shown in Fig. 18 described above. This improves mold releasability when molding the grid structure 20 using a transfer technique such as imprinting, and allows the inclined grid structure to be molded relatively easily and with high precision.

[0372] 7.2. Preferred Range of Inclination Angle α Next, a preferred range of the inclination angle α of the convex streak portion 22 of the inclined grid structure according to the second embodiment will be described.

[0373] (1) 0°<α≦15° The inclination angle α of the ridge portions 22 is preferably greater than 0° and less than or equal to 15°. If the inclination angle α of the ridge portions 22 exceeds 15°, the inclination of the ridge portions 22 is too great, and the transmittance Tp may be lower than when the ridge portions 22 are not inclined. In contrast, if the inclination angle α of the ridge portions 22 is 15° or less, the ridge portions 22 can be inclined at an appropriate inclination angle α to match the obliquely incident light incident from the inclined side of the ridge portions 22. Therefore, the transmittance Tp can be increased compared to when the ridge portions 22 are not inclined, and the polarization separation characteristics (Tp×Rs characteristics) can be improved.

[0374] 18 , when obliquely incident light 31 is incident at an incident angle θ=−45° from the side where the protruding ridge portion 22 is inclined, if the inclination angle α is greater than 0° and less than or equal to 15°, the grid structure 20 can be given directivity suitable for the obliquely incident light 31. Therefore, while maintaining the reflectance Rs at a high value of, for example, 90% or more, the transmittance Tp can be increased to, for example, 84% or more, and therefore Tp×Rs can be increased to a reference value or more (for example, 76% or more).

[0375] The reference value is a reference value of Tp×Rs measured using the grid structure 20 according to the first embodiment in which the convex stripes 22 are not inclined, and is, for example, 76%. If the value of Tp×Rs can be increased to or above the reference value by adopting the inclined grid structure according to the second embodiment, it can be said that there is an effect of improving the polarization separation characteristic (Tp×Rs) for obliquely incident light incident from a specific inclined direction.

[0376] 19 , when obliquely incident light 31 is incident at an incident angle θ=−45° from the side where the protruding ridge portion 22 is inclined, if the inclination angle α is greater than 0° and less than or equal to 10°, the grid structure 20 can be given directivity suitable for the obliquely incident light. Therefore, while maintaining the reflectance Rs at a high value of, for example, 90% or more, the transmittance Tp can be increased to, for example, 84% or more, and therefore Tp×Rs can be increased to a reference value or more (for example, 76% or more).

[0377] (2) 5°≦α≦10° Furthermore, it is more preferable that the inclination angle α of the convex ridge portion 22 is 5° or more and 10° or less. This allows the convex ridge portion 22 to be inclined at a more appropriate inclination angle α in accordance with the obliquely incident light 31 incident from the inclined side of the convex ridge portion 22. Therefore, the transmittance Tp can be further increased, and the polarization separation characteristic (Tp×Rs characteristic) can be further improved.

[0378] 18 , when obliquely incident light 31 (θ=−45°) is incident from the inclined side of the protruding ridge portion 22, if the inclination angle α is 5° or more and 10° or less, the grid structure 20 can be endowed with directivity that is more suitable for the obliquely incident light. Therefore, while maintaining Rs at a high value of, for example, 90% or more, Tp can be further increased to, for example, 85.8% or more, and therefore Tp×Rs can be further increased to, for example, 77.3% or more.

[0379] 19 , when the obliquely incident light 31 (θ=−45°) is incident, if the inclination angle α is 5° or more and 10° or less, the grid structure 20 can be given directivity that is more suitable for the obliquely incident light 31. Therefore, while maintaining Rs at a high value of, for example, 90% or more, Tp can be further increased to, for example, 84.5% or more, and therefore Tp×Rs can be further increased to, for example, 76.7% or more.

[0380] 7.3. Preferred Range of Coverage Rc Next, a preferred range of the coverage Rc when the side surface 22b of the ridge portion 22 is covered with the reflective film 30 in the inclined grid structure according to the second embodiment will be described.

[0381] 18 and 19 , in the grid structure 20 having the inclined grid structure according to the second embodiment, the reflective film 30 (functional film) covers the tip 22 a and the upper sides of both side surfaces 22 b 1 and 22 b 2 (hereinafter, sometimes collectively referred to as “side surfaces 22 b”) of the inclined protruding rib portion 22. The coverage Rc of both side surfaces 22 b 1 and 22 b 2 of the protruding rib portion 22 by the reflective film 30 (hereinafter, referred to as “coverage rates Rc1 and Rc2,” respectively) is preferably 30% or more and 70% or less.

[0382] In this way, the reflective film 30 covers both side surfaces 22b1, 22b2 of the inclined ridge portion 22, and the coverage rates Rc1, Rc2 are 30% or more and 70% or less, so that the inclined grid structure having the inclined ridge portion 22 can accommodate both "obliquely incident light 31 in the negative direction" and "obliquely incident light 32 in the positive direction." Therefore, regardless of the direction from which obliquely incident light is incident, a fairly good transmittance (transmittance Tp) and polarization separation characteristics (Tp×Rs characteristics) can be achieved.

[0383] In this specification, "obliquely incident light in the negative direction" refers to obliquely incident light that is incident from the side where the ridges 22 are inclined relative to the surface (XY plane) of the polarizing element 1. The incident angle θ of "obliquely incident light 31 in the negative direction" is a negative value less than 0° (θ<0°). In other words, when the incident angle θ is a negative value (for example, θ=−45°), this means that the obliquely incident light is incident obliquely from the direction of the inclined side of the ridges 22 (the positive direction of the X axis) toward the negative direction of the X axis.

[0384] On the other hand, "obliquely incident light in the positive direction" refers to obliquely incident light that is incident from the side opposite to the inclined side of the ridge portion 22. The incident angle θ of "obliquely incident light in the positive direction" is a positive value greater than 0° (θ>0°). In other words, when the incident angle θ is a positive value (for example, θ=+45°), this means that the obliquely incident light is incident obliquely from the direction opposite to the inclined side of the ridge portion 22 (the negative direction of the X axis) toward the inclined side of the ridge portion 22 (the positive direction of the X axis).

[0385] 18 and 19, for example, the protruding ridge portion 22 is inclined to the right in the X direction (positive direction of the X axis) with respect to the Z direction. Therefore, the "obliquely incident light in the negative direction" is the obliquely incident light 31 that is incident from the right in the X direction (positive direction of the X axis) toward the left in the X direction (negative direction of the X axis) at a negative incident angle θ (for example, θ = -45°). The "obliquely incident light in the positive direction" is the obliquely incident light 32 that is incident from the left in the X direction (negative direction of the X axis) toward the right in the X direction (positive direction of the X axis) at a positive incident angle θ (for example, θ = +45°).

[0386] The range of the incidence angle θ of the obliquely incident light varies depending on the specifications and applications of the polarizing element 1, but is, for example, a range of a predetermined angle width (e.g., ±15°, ±10°) centered on the central obliquely incident light from an oblique 45° angle. More specifically, when the incidence angle of the central obliquely incident light is 45° and the angle width is ±15°, the range of the incidence angle θ of the obliquely incident light is, for example, +45°±15° (i.e., +30° to 60°) or −45°±15° (i.e., −60° to −30°). The incidence angle of the central obliquely incident light may be various angles other than the above example of 45°, such as 30° or 55°. Furthermore, the predetermined angle width may also be various angle widths other than the above examples of ±15° and ±10°, such as ±5°, ±20°, or ±25°.

[0387] 7.3.2. First Side and Second Side of the Convex Ridge Portion The first side of the convex rib portion 22 is the side of the both side surfaces 22b, 22b of the convex rib portion 22 on the inclined side of the convex rib portion 22. On the other hand, the second side of the convex rib portion 22 is the side of the both side surfaces 22b, 22b of the convex rib portion 22 opposite the inclined side of the convex rib portion 22.

[0388] 18, the upper portion 22c of the convex rib portion 22 is inclined to the right in the X direction, and therefore, of the both side surfaces 22b, 22b of the upper portion 22c of the convex rib portion 22, the right side surface 22b1 of the upper portion 22c of the convex rib portion 22 is the first side surface, and the left side surface 22b2 of the upper portion 22c of the convex rib portion 22 is the second side surface. Also, in the example of Fig. 19, the entire convex rib portion 22 is inclined to the right in the X direction, and therefore, of the both side surfaces 22b, 22b of the entire convex rib portion 22, the right side surface 22b1 of the convex rib portion 22 is the first side surface, and the left side surface 22b2 of the convex rib portion 22 is the second side surface.

[0389] The coverage Rc1 of the first side surface 22b1 of the convex rib portion 22 is expressed by the following formula (11): Rc1 [%] = (Hx1 / H) × 100 (11), where H: height of the convex rib portion 22 in the Z direction [nm], and Hx1: height of the portion of the first side surface 22b1 of the convex rib portion 22 that is covered by the reflective film 30 in the Z direction [nm].

[0390] Similarly, the coverage Rc2 of the second side surface 22b2 of the convex rib portion 22 is expressed by the following formula (12): Rc2 [%] = (Hx2 / H) × 100 (12), where H: height of the convex rib portion 22 in the Z direction [nm], and Hx2: height of the portion of the second side surface 22b2 of the convex rib portion 22 that is covered by the reflective film 30 in the Z direction [nm].

[0391] <7.3.3. Coverage Rc1 of the first side surface of the convex rib portion> (1) Oblique incident light in the - direction (35%≦Rc1≦50%) When oblique incident light 31 is incident on the surface of the polarizing element 1 from the side where the convex rib portion 22 is inclined (that is, when "oblique incident light in the - direction" is incident at a negative incident angle θ), the coverage Rc1 of the first side surface 22b1 of the convex rib portion 22 is preferably 35% or more and 50% or less.

[0392] As a result, when "obliquely incident light in the negative direction" is incident, the coverage Rc1 of the first side surface 22b1 can be adjusted within an appropriate range to match the negative incident angle θ (for example, θ = -45°). Therefore, while maintaining the reflectance Rs at a high value, for example, 90% or more, the transmittance Tp can be increased to, for example, 84% or more, and Tp × Rs can be increased to a reference value or higher (for example, 76% or more) (see FIG. 23).

[0393] (2) Obliquely incident light in the + direction (40%≦Rc1≦53%) When obliquely incident light 32 is incident on the surface of the polarizing element 1 from the side opposite to the side on which the convex rib portion 22 is inclined (i.e., when ``obliquely incident light in the + direction'' is incident at a positive incident angle θ), it is preferable that the coverage Rc1 of the first side surface 22b1 of the convex rib portion 22 is 40% or more and 53% or less.

[0394] As a result, when "obliquely incident light in the positive direction" is incident, the coverage Rc1 of the first side surface 22b1 can be adjusted within an appropriate range to match the positive incident angle θ (e.g., θ = +45°). Therefore, while maintaining the reflectance Rs at a high value, e.g., 90% or more, the transmittance Tp can be increased to, e.g., 84% or more, and Tp × Rs can be increased to a reference value or higher (e.g., 76% or more) (see FIG. 23).

[0395] <7.3.4. Coverage Rc2 of the second side surface of the convex rib portion> (1) Oblique incident light in the - direction (35%≦Rc2≦55%) When oblique incident light 31 is incident on the surface of the polarizing element 1 from the side where the convex rib portion 22 is inclined (that is, when “oblique incident light in the - direction” is incident at a negative incident angle θ), the coverage Rc2 of the second side surface 22b2 of the convex rib portion 22 is preferably 35% or more and 55% or less.

[0396] As a result, when "obliquely incident light in the negative direction" is incident, the coverage Rc2 of the second side surface 22b2 can be adjusted to an appropriate range in accordance with a negative incident angle θ (for example, θ = -45°). Therefore, while maintaining the reflectance Rs at a high value, for example, 90% or more, the transmittance Tp can be increased to, for example, 84% or more, and Tp × Rs can be increased to a reference value or more (for example, 76% or more) (see FIG. 24).

[0397] (2) Obliquely incident light in the + direction (35%≦Rc2≦45%) When obliquely incident light 32 is incident on the surface of the polarizing element 1 from the side opposite to the side on which the convex rib portion 22 is inclined (i.e., when ``obliquely incident light in the + direction'' is incident at a positive incident angle θ), it is preferable that the coverage Rc2 of the second side surface 22b2 of the convex rib portion 22 be 35% or more and 45% or less.

[0398] As a result, when "obliquely incident light in the positive direction" is incident, the coverage Rc2 of the second side surface 22b2 can be adjusted within an appropriate range to match the positive incident angle θ (e.g., θ = +45°). Therefore, while maintaining the reflectance Rs at a high value, e.g., 90% or more, the transmittance Tp can be increased to, e.g., 84% or more, and Tp × Rs can be increased to a reference value or higher (e.g., 76% or more) (see FIG. 24).

[0399] Next, examples of the present invention will be described. However, the examples described below are specific examples given to illustrate the configuration and effects of the polarizing element 1 according to the above-described embodiment, and the present invention is not limited to the following examples.

[0400] <1. Verification Results of the Inclined Grid Structure> As an example of the present invention, a model of the wire-grid polarizer 1 having the inclined grid structure according to the second embodiment described above was created, and various characteristics of the model were simulated to evaluate the wire-grid polarizer 1 (incline angle α > 0°) according to the example. Furthermore, for comparison with the wire-grid polarizer 1 having the inclined grid structure according to the example of the present invention (incline angle α > 0°), a model of a wire-grid polarizer 1 (incline angle α = 0°) according to a comparative example that does not have the inclined grid structure was also created, and simulation and evaluation were similarly performed. Note that, for ease of explanation, the following reference numerals representing the components of the polarizer 1 (substrate 10, grid structure 20, base portion 21, ridge portion 22, reflective film 30, etc.) and the symbols representing the various dimensions of these components are assigned the same reference numerals and symbols in both the example and the comparative example.

[0401] The symbols used in the following description to represent various dimensions of the polarizing element 1 are as follows: P: pitch of the ridges 22 W: Ｔ　　 W: width of the top of the ridge portion 22 (ridge portion top width) Ｍ　　 W: width of the central position of the ridge portion 22 in the height direction (central width of the ridge portion) Ｂ　　 W: Width of the bottom of the ridge portion 22 (grid bottom width) ＭＡＸ: maximum width of the reflective film 30 that covers the convex rib portion 22 (maximum grid width) H: height of the convex rib portion 22 Hx: height of the portion of the side surface 22b of the convex rib portion 22 that is covered by the reflective film 30 Hx1: height of the portion of the first side surface 22b1 of the convex rib portion 22 that is covered by the reflective film 30 Hx2: height of the portion of the second side surface 22b2 of the convex rib portion 22 that is covered by the reflective film 30 Dt: thickness of the reflective film 30 that covers the tip 22a of the convex rib portion 22 (tip thickness of the reflective film 30) Ds: thickness of the reflective film 30 that covers the side surface 22b of the convex rib portion 22 (side surface thickness of the reflective film 30) Rc: coverage rate of the side surface 22b of the convex rib portion 22 by the reflective film 30 Rc1: coverage rate of the first side surface 22b1 of the convex rib portion 22 by the reflective film 30 Rc2 : Coverage rate of the second side surface 22b2 of the convex rib portion 22 by the reflective film 30 Rr: Opening rate of the side surface 22b of the convex rib portion 22 by the reflective film 30 Rr1: Opening rate of the first side surface 22b1 of the convex rib portion 22 by the reflective film 30 Rr2: Opening rate of the second side surface 22b2 of the convex rib portion 22 by the reflective film 30 θ: Incident angle of incident light λ: Wavelength of incident light α: Inclination angle of the convex rib portion 22

[0402] (Fortieth Embodiment) First, a fortieth embodiment of the present invention will be described with reference to Figs.

[0403] As shown in Fig. 20 , a model of a polarizing element 1 according to Example 40 was fabricated. The polarizing element 1 according to Example 40 includes a glass substrate 10 and a grid structure 20 made of an ultraviolet-curable resin (acrylic resin). The grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and a plurality of ridge portions 22 formed to protrude in a grid pattern from the base portion 21. The cross-sectional shape of the ridge portions 22 is a vertically elongated trapezoid, and is tapered toward the tips 22a of the ridge portions 22.

[0404] The reflective film 30 covering the ridge portion 22 in Example 40 is an Al film. The reflective film 30 is formed to cover the tip 22a of the ridge portion 22 and the upper sides of both side surfaces 22b1 and 22b2. However, the reflective film 30 does not cover the lower sides of both side surfaces 22b1 and 22b2 of the ridge portion 22 or the base portion 21. The coverage rates Rc1 and Rc2 of both side surfaces 22b1 and 22b2 of the ridge portion 22 by the reflective film 30 are 45%. In this way, the reflective film 30 in Example 40 roundly covers the top of the ridge portion 22 (the tip 22a and the upper sides of both side surfaces 22b1 and 22b2). The surface of the reflective film 30 is approximately elliptical, bulging outward, and bulging in the width direction of the ridge portion 22.

[0405] As a result, the grid according to Example 40 (a structure combining the ridges 22 and the reflective film 30) has the special tree shape described above. ＭＡＸ (the width of the grid at the most bulging portion of the reflective film 30) is the width W of the bottom of the ridge portion 22 Ｂ (the width of the ridge portion 22 at a height position 20% above the bottom of the ridge portion 22) or more.

[0406] In Example 40, in order to provide a tilted grid structure, the upper portion 22c of the ridge portion 22 was tilted at a tilt angle α to one side in the width direction of the ridge portion 22 (the right side in FIG. 20(a)). The tilted upper portion 22c was the portion of the upper 50% in the height direction of the ridge portion 22. The tilt angle α in Example 40 was 5°, 10°, or 15°.

[0407] On the other hand, in the model of the polarizing element 1 according to Comparative Example 40, the convex ridge portions 22 were not inclined, and no inclined grid structure was provided. That is, in Comparative Example 40, the inclination angle α was set to 0°, and the convex ridge portions 22 extended straight upward in the normal direction (Z direction) of the surface of the substrate 10.

[0408] Furthermore, as Comparative Example 41, a model was also created in which the upper portion 22c of the ridge portion 22 was inclined at a large inclination angle α of 15° or more to one side in the width direction of the ridge portion 22 (the right side in FIG. 20(a)). The inclination angles α of Comparative Example 41 were 20°, 25°, 30°, 40°, and 45°.

[0409] The dimensions and shapes of the parts of the models of the polarizing elements 1 according to Example 40 and Comparative Examples 40 and 41 are as follows: P: 142 nm W Ｔ　　 : 17 nm W Ｂ　　 : 65 nm W ＭＡＸ :65nm H :225nm Hx=Hx1=Hx2 :101nm Dt :38nm Ds :17.5nm (maximum value) Rc=Rc1=Rc2 :45% Rr=Rr1=Rr2 :55% θ :-45°, +45° λ :430-680nm α : 5°, 10°, 15° (Example 40) α : 0° (Comparative Example 40) α : 20°, 25°, 30°, 35°, 40°, 45° (Comparative Example 41)

[0410] Simulations were performed on the models of the polarizing element 1 according to Example 40 and Comparative Examples 40 and 41 prepared as described above, and the transmission axis transmittance (Tp), transmission axis reflectance (Ts), reflection axis transmittance (Rp), reflection axis reflectance (Rs), and Tp × Rs required for a polarizing beam splitter (PBS) were calculated. In this case, for each of Example 40 (α = 5° to 15°), Comparative Example 40 (α = 0°), and Comparative Example 41 (α = 20° to 45°), the values ​​of Tp, Ts, Rp, and Rs were calculated for the cases where "oblique incident light in the - direction (θ = -45°)" was incident and "oblique incident light in the + direction (θ = +45°)" was incident. The values ​​of Tp, Ts, Rp, and Rs were calculated by varying the wavelength λ of the oblique incident light in the range of 430 to 680 nm, and the average values ​​of the multiple Tp, Ts, Rp, and Rs values ​​calculated for the oblique incident light of each wavelength λ were used.

[0411] The relationships between the Tp characteristics, Rs characteristics, and Tp×Rs characteristics, and the tilt angle α, obtained as described above, for Example 40 and Comparative Examples 40 and 41 are shown in the graphs of Figures 20(b) to (d) and Figures 21(b) to (d). Note that although the scales of the tilt angle α on the horizontal axis are different in Figures 20(b) to (d) and Figures 21(b) to (d), they show the same Tp characteristics, Rs characteristics, and Tp×Rs characteristics.

[0412] 20(a), in the model of the polarizing element 1 according to Example 40, the reflective film 30 covers the tops of the ridge portions 22 and leaves the bottoms of the ridge portions 22 open, with a coverage Rc of 45%. Therefore, the grid according to Example 40 (a structure combining the ridge portions 22 and the reflective film 30) has the special tree-like shape described above. Furthermore, the grid according to Example 40 has a bent grid tilt structure in which the upper portions 22c of the ridge portions 22 are bent and tilted to the right, and the tilt angle α of the upper portions 22c of the ridge portions 22 is adjusted to an appropriate range of more than 0° and not more than 15°.

[0413] As shown in Figures 20 and 21, in Example 40 (α = 5° to 15°), the inclination angle α of the bent grid inclination structure is within an appropriate range, and therefore, compared to Comparative Example 40 (α = 0°) and Comparative Example 41 (α = 20° to 45°), Example 40 has superior transmittance (Tp characteristics) and polarization separation characteristics (Tp x Rs characteristics) for obliquely incident light from a specific inclination direction (for example, obliquely incident light in the negative direction (θ = -45°) and obliquely incident light in the positive direction (θ = +45°)).

[0414] 20(c) and 21(c), when the reflectivity Rs is compared, Rs remains high at 90% or more regardless of the magnitude of the tilt angle α within the range of 0° to 45°. Therefore, when the convex ridge portion 22 is tilted as in Example 40 (α = 5° to 15°), a high Rs of 90% or more can be ensured, just as in the case of not tilting the convex ridge portion 22 as in Comparative Example 40 (α = 0°), and it can be seen that the reflective film 30 can exhibit excellent reflectivity (Rs characteristics).

[0415] Next, comparing the transmittance Tp, as shown in FIG. 20( b), the Tp of Comparative Example 40 (α = 0°), which is the reference, is approximately 84%. Furthermore, as shown in FIG. 21( b), in Comparative Example 41 (α = 20° to 45°), the Tp is 82% or less, which is lower than the reference Comparative Example 40 (α = 0°). In Comparative Example 41, Tp decreases as α increases in the range of 20° or more, and when α = 45°, Tp drops to 60% or less. Therefore, in the case of the bent grid inclination structure shown in FIG. 20( a), when α is 20° or more, as in Comparative Example 41, the inclination angle α of the convex ridge portion 22 is too large, resulting in a small Tp, which is undesirable.

[0416] In contrast, the Tp of Example 40 (α=5° to 15°) is 84.3% or more, which is higher than the reference Comparative Example 40 (α=0°) for both obliquely incident light in the + direction (θ=+45°) and obliquely incident light in the - direction (θ=-45°). In particular, when α=5° and 10° in Example 40, excellent directivity is exhibited for obliquely incident light in the - direction (θ=-45°), and the Tp is 85.8% or more, which is significantly higher than that of Comparative Example 40 (α=0°).

[0417] Therefore, it can be seen that the transmittance (Tp characteristics) for obliquely incident light from a specific tilt direction (θ=−45°, +45°) can be improved when α is in the appropriate range of more than 0° and not more than 15°, as in Example 40. In particular, it can be seen that when α is in the preferred range of 5° or more and 10° or less, the transmittance (Tp characteristics) for obliquely incident light in the negative direction (θ=−45°) is very excellent.

[0418] Next, we compare Tp×Rs, which is the product of Rs and Tp. As shown in FIG. 20(d), Tp×Rs for Comparative Example 40 (α = 0°), which serves as the reference, is approximately 76%. Furthermore, as shown in FIG. 21(d), in Comparative Example 41 (α = 20° to 45°), Tp×Rs is 75% or less, which is lower than the reference for Comparative Example 40 (α = 0°). Furthermore, in Comparative Example 41, Tp×Rs decreases as α increases in the range of 20° or more, and when α = 45°, Tp×Rs drops to 55% or less. Therefore, in the case of the bent grid inclination structure shown in FIG. 20(a), when α is 20° or more, as in Comparative Example 41, α is too large, resulting in a small Tp×Rs, which is undesirable.

[0419] In contrast, the Tp×Rs of Example 40 (α=5° to 15°) is 76.2% or more, which is higher than the reference Comparative Example 40 for both obliquely incident light in the + direction (θ=+45°) and obliquely incident light in the - direction (θ=-45°). In particular, when α=5° and 10° in Example 40, excellent directivity is exhibited for obliquely incident light in the - direction (θ=-45°), and the Tp×Rs is 77.3% or more, which is significantly higher than that of Comparative Example 40 (α=0°).

[0420] 20(a), it can be seen that the polarization separation characteristics (Tp×Rs characteristics) for obliquely incident light from a specific tilt direction (θ=−45°, +45°) can be improved if α is within the appropriate range of more than 0° and not more than 15°, as in Example 40. In particular, it can be seen that if α is within the preferred range of 5° or more and 10° or less, it has very excellent polarization separation characteristics (Tp×Rs characteristics) for obliquely incident light in the negative direction (θ=−45°).

[0421] Thus, with regard to the Tp×Rs characteristics required for a polarizing beam splitter (PBS), Example 40 is superior to Comparative Examples 40 and 41. In particular, when the tilt angle α is 5° to 10°, a Tp×Rs characteristic with directivity for obliquely incident light in the negative direction (θ = -45°) is obtained. Therefore, when the polarizing element 1 according to Example 40 is used as a polarizing beam splitter, it is found that the transmittance (transmittance Tp) and polarization separation characteristics (Tp×Rs characteristics) of P-polarized light are significantly superior for obliquely incident light incident from a specific direction. Therefore, it can be said that the polarization separation characteristics required for a polarizing beam splitter can be fully satisfied for obliquely incident light incident from that specific direction. Therefore, when the polarizing element 1 according to Example 40 is used as a polarizing beam splitter to project an image, the brightness balance of the displayed image is well-balanced as seen by the observer, and the image quality is also good.

[0422] As described above, in Example 40, in the bent grid inclination structure shown in FIG. 20( a), the inclination angle α of the convex streak portion 22 is adjusted to an appropriate angle of greater than 0° and less than 15°. As a result, in Example 40, Tp can be increased to greater than 84% while maintaining Rs at a high value of 90% or more, and Tp×Rs can be increased to greater than 76%, which is the reference value. Therefore, it can be seen that Example 40 provides better transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) than the reference Comparative Example 40 for both obliquely incident light in the positive direction (θ=+45°) and obliquely incident light in the negative direction (θ=−45°).

[0423] In particular, it can be seen that for obliquely incident light in the negative direction (θ=−45°), the transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) can be significantly improved by tilting the upper part 22c of the convex ridge portion 22 at an inclination angle α of 5° or more and 10° or less. Therefore, it can be said that a polarizing element 1 can be provided that has directionality for obliquely incident light in the negative direction (θ=−45°) and has excellent transmittance and polarization separation characteristics.

[0424] (Forty-Second Embodiment) Next, a forty-second embodiment of the present invention will be described with reference to FIG.

[0425] 22 , a model of the polarizing element 1 according to Example 42 was fabricated. In Example 42, a grid having a special tree shape (a structure combining the protruding ridges 22 and the reflective film 30) was fabricated in the same manner as in Example 40 described above, except for the manner in which the protruding ridges 22 were inclined.

[0426] In Example 42, in order to provide a grid inclination structure, the entire ridge portion 22 was inclined at an inclination angle α to one side in the width direction of the ridge portion 22 (the right side in FIG. 22( a)). The inclination angle α in Example 42 was set to 5°, 10°, and 15°.

[0427] On the other hand, in the model of the polarizing element 1 according to Comparative Example 42, the convex ridge portions 22 were not inclined, and no inclined grid structure was provided. That is, in Comparative Example 42, the inclination angle α was set to 0°, and the convex ridge portions 22 extended straight upward in the normal direction (Z direction) of the surface of the substrate 10.

[0428] Furthermore, as Comparative Example 43, a model was also created in which the entire ridge portion 22 was inclined at a large inclination angle α of more than 10° to one side in the width direction of the ridge portion 22 (the right side in FIG. 22( a)). The inclination angles α in Comparative Example 43 were 15° and 30°.

[0429] The dimensions and shapes of the parts of the models of the polarizing elements 1 according to Example 42 and Comparative Examples 42 and 43 are as follows: P: 142 nm W Ｔ　　 : 17 nm W Ｂ　　 : 65 nm W ＭＡＸ :65nm H :225nm Hx=Hx1=Hx2 :101nm Dt :38nm Ds :17.5nm (maximum value) Rc=Rc1=Rc2 :45% Rr=Rr1=Rr2 :55% θ :-45°, +45° λ :430-680nm α : 0° (Comparative Example 42) α : 5°, 10° (Example 42) α : 15°, 30° (Comparative Example 43)

[0430] Simulations were performed on the models of the polarizing element 1 according to Example 42 and Comparative Examples 42 and 43 prepared as described above, and Tp, Ts, Rp, Rs, and Tp×Rs were calculated. In this simulation, for each of Example 42 (α = 5° to 15°), Comparative Example 42 (α = 0°), and Comparative Example 43 (α = 30°), the values ​​of Tp, Ts, Rp, and Rs were calculated for the cases of "obliquely incident light in the - direction (θ = -45°)" and "obliquely incident light in the + direction (θ = +45°)." The values ​​of Tp, Ts, Rp, and Rs were calculated by varying the wavelength λ of the obliquely incident light in the range of 430 to 680 nm and averaging the values ​​of Tp, Ts, Rp, and Rs calculated for the obliquely incident light of each wavelength λ.

[0431] The relationships between the Tp characteristics, Rs characteristics, and Tp×Rs characteristics of Example 42 and Comparative Examples 42 and 43, which were obtained as described above, and the tilt angle α, are shown in the graphs of FIGS.

[0432] 22(a), in the model of the polarizing element 1 according to Example 42, the reflective film 30 covers the tops of the ridge portions 22 and leaves the bottoms of the ridge portions 22 open, with a coverage Rc of 45%. Therefore, the grid according to Example 42 (a structure combining the ridge portions 22 and the reflective film 30) has the special tree-like shape described above. Furthermore, the grid according to Example 42 has an overall grid tilt structure in which the entire ridge portions 22 are tilted to the right, and the overall tilt angle α of the ridge portions 22 is adjusted to an appropriate range of more than 0° and not more than 15°.

[0433] As shown in Figure 22, in Example 42 (α = 5° to 10°), the tilt angle α of the overall grid tilt structure is within an appropriate range, and therefore, compared to Comparative Example 42 (α = 0°) and Comparative Example 43 (α = 30°), Example 42 has superior transmittance (Tp characteristics) and polarization separation characteristics (Tp x Rs characteristics) for obliquely incident light from a specific tilt direction (for example, obliquely incident light in the negative direction (θ = -45°) and obliquely incident light in the positive direction (θ = +45°)).

[0434] 22(c), when the reflectance Rs is compared, Rs remains high at 90% or more regardless of the magnitude of the tilt angle α within the range of 0° to 30°. Therefore, when the convex ridge portion 22 is tilted as in Example 42 (α=5° to 15°), a high Rs of 90% or more can be ensured, just as in the case of not tilting the convex ridge portion 22 as in Comparative Example 42 (α=0°), and it can be seen that the reflective film 30 can exhibit excellent reflectivity (Rs characteristics).

[0435] Next, comparing the transmittance Tp, as shown in FIG. 22( b), the Tp of the reference comparative example 42 (α = 0°) is approximately 84%. Furthermore, in comparative example 43 (α = 15°, 30°), the Tp is 83% or less, which is significantly lower than the reference comparative example 42 (α = 0°). Furthermore, in comparative example 43, as α increases in the range of 15° or more, Tp decreases. Therefore, in the case of the overall inclined grid structure shown in FIG. 22( a), when α is 15° or more as in comparative example 43, the inclination angle α of the ridge portion 22 is too large, resulting in a small Tp, which is undesirable.

[0436] In contrast, the Tp of Example 42 (α = 5°, 10°) is 84% ​​or more, which is equal to or greater than the reference Comparative Example 42 (α = 0°) for both oblique incident light in the + direction (θ = +45°) and oblique incident light in the - direction (θ = -45°). In particular, for oblique incident light in the - direction (θ = -45°), the Tp of Example 42 (α = 5°, 10°) is 84.5% or more, which is significantly higher than that of Comparative Example 42 (α = 0°). Furthermore, for α = 5° in Example 42, the Tp is 84.5% or more for both oblique incident light in the + direction (θ = +45°) and oblique incident light in the - direction (θ = -45°), which is significantly higher than that of Comparative Example 42 (α = 0°).

[0437] 22(a), it can be seen that the transmittance (Tp characteristic) for obliquely incident light from specific tilt directions (θ=−45°, +45°) can be improved if α is within the appropriate range of more than 0° and not more than 10°, as in Example 42. In particular, it can be seen that the transmittance (Tp characteristic) for obliquely incident light in the negative direction (θ=−45°) is very good.

[0438] Next, we compare Tp×Rs, which is the product of Rs and Tp. As shown in FIG. 22(d), Tp×Rs for Comparative Example 42 (α = 0°), which is the reference, is approximately 76%. Furthermore, in Comparative Example 43 (α = 15°, 30°), Tp×Rs is 75.2% or less, which is lower than the reference Comparative Example 42 (α = 0°). Therefore, in the case of the overall grid inclination structure shown in FIG. 22(a), when α is 15° or more, as in Comparative Example 43, α is too large, resulting in a small Tp×Rs, which is undesirable.

[0439] In contrast, the Tp×Rs of Example 42 (α=5°, 10°) is 76.2% or more, which is equal to or better than the reference Comparative Example 42 for both oblique incident light in the + direction (θ=+45°) and oblique incident light in the - direction (θ=-45°). In particular, it has excellent directivity for oblique incident light in the - direction (θ=-45°), and the Tp×Rs is 76.7% or more, which is significantly higher than that of Comparative Example 42 (α=0°).

[0440] 22(a), it can be seen that the polarization separation characteristics (Tp×Rs characteristics) for obliquely incident light from a specific tilt direction (θ=−45°, +45°) can be improved if α is within the appropriate range of more than 0° and not more than 10°, as in Example 42. In particular, it can be seen that if α is within the preferred range of not less than 5° and not more than 10°, it has very excellent polarization separation characteristics (Tp×Rs characteristics) for obliquely incident light in the negative direction (θ=−45°).

[0441] As described above, in Example 42, in the overall grid inclination structure shown in FIG. 22( a), the inclination angle α of the convex streak portion 22 is adjusted to an appropriate angle of more than 0° and less than 10°. As a result, in Example 42, Tp can be increased to 84% or more while maintaining Rs at a high value of 90% or more, and Tp×Rs can be increased to more than 76%, which is the reference value. Therefore, it can be seen that Example 42 provides better transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) than the reference Comparative Example 42 for both obliquely incident light in the positive direction (θ=+45°) and obliquely incident light in the negative direction (θ=−45°).

[0442] In particular, it can be seen that for obliquely incident light in the negative direction (θ=−45°), the transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) can be significantly improved by tilting the entire ridge portion 22 at an inclination angle α of 5° or more and 10° or less. Therefore, it can be said that a polarizing element 1 can be provided that has directionality for obliquely incident light in the negative direction (θ=−45°) and has excellent transmittance and polarization separation characteristics.

[0443] (Forty-third embodiment) Next, a forty-third embodiment of the present invention will be described with reference to FIG.

[0444] As shown in Figure 23, a model of a polarizing element 1 according to Example 43 was fabricated. In Example 43, a grid (a structure combining the ridge portions 22 and the reflective film 30) having a special tree shape was fabricated in the same manner as in Example 40 described above, except that the coverage Rc1 of the first side surface 22b1 of the ridge portions 22 was changed. In Example 43, in order to provide a tilted grid structure, the upper portions 22c of the ridge portions 22 (the upper 50% of the ridge portions 22) were tilted at an inclination angle α to one side in the width direction of the ridge portions 22 (the right side in Figure 23(a)). The inclination angle α in Example 43 was fixed at 10°.

[0445] In Example 44, the coverage Rc of the reflective film 30 covering the protruding rib portion 22 was varied between the first side surface 22b1 and the second side surface 22b2. The first side surface 22b1 is the side surface 22b on the inclined side of the protruding rib portion 22 (the side surface on the right in FIG. 23( a)), and the second side surface 22b2 is the side surface 22b opposite the inclined side of the protruding rib portion 22 (the side surface on the left in FIG. 23( a)). In Example 43, the coverage Rc2 (= Hx2 / H) of the second side surface 22b2 was fixed at 45%, and the coverage Rc1 (= Hx1 / H) of the first side surface 22b1 was varied within a range of 35 to 55%.

[0446] The dimensions and shapes of the parts of the model of the polarizing element 1 according to Example 43 are as follows: P: 142 nm W Ｔ　　 : 17 nm W Ｂ　　 : 65 nm W ＭＡＸ : 65 nm H : 225 nm Hx1: 79 nm, 90 nm, 101 nm, 113 nm, 124 nm (variable value) Hx2: 101 nm (fixed value) Dt : 38 nm Ds : 17.5 nm (maximum value) Rc1 : 35%, 40%, 45%, 50%, 55% (variable value) Rr1 : 65%, 60%, 55%, 50%, 45% (variable value) Rc2 : 45% (fixed value) Rr2 : 55% (fixed value) θ : -45°, +45° λ : 430 to 680 nm α : 10° (fixed value)

[0447] A simulation was performed on the model of the polarizing element 1 according to Example 43 prepared as described above, and Tp, Ts, Rp, Rs, and Tp × Rs were calculated. The values ​​of Tp, Ts, Rp, and Rs were calculated for the cases of "obliquely incident light in the negative direction (θ = -45°)" and "obliquely incident light in the positive direction (θ = +45°)." The wavelength λ of the obliquely incident light was varied in the range of 430 to 680 nm, and the average values ​​of multiple Tp, Ts, Rp, and Rs calculated for obliquely incident light of each wavelength λ were used to calculate the values ​​of Tp, Ts, Rp, and Rs. The contrast (CR) of the transmitted light was also calculated by dividing Tp by Ts (CR = Tp / Ts).

[0448] The relationships between the Tp characteristics, Rs characteristics, Tp×Rs characteristics, contrast CR, and coverage Rc1 of the first side surface 22b1 according to Example 43, which were determined as described above, are shown in the graphs of FIGS.

[0449] 23(c), the reflectance Rs of Example 43 maintains a high value of 90% or more in both the cases of "obliquely incident light in the negative direction (θ=−45°)" and "obliquely incident light in the positive direction (θ=+45°)," regardless of the magnitude of the coverage Rc1 (35 to 55%). Therefore, it is understood that a high Rs of 90% or more can be ensured regardless of Rc1, and excellent reflectivity (Rs characteristics) can be exhibited by the reflective film 30.

[0450] 23(b) and 23(d), the behavior of the Tp characteristics and the Tp×Rs characteristics according to the coverage Rc1 differs depending on whether the incident direction of the obliquely incident light is the "negative direction (θ=-45°)" or the "positive direction (θ=+45°)." Below, the Tp and Tp×Rs characteristics of Example 43 (α=10°) are compared with the reference value of Tp (84%) and the reference value of Tp×Rs (76%) of Comparative Example 40 (α=0°) shown in FIG. 20 described above, to evaluate the Tp and Tp×Rs characteristics of Example 43.

[0451] (1) Obliquely incident light in the negative direction (35%≦Rc1≦50%) First, when the incident direction is the "negative direction (θ=−45°)," in Example 43, if Rc1 is in the range of 35% or more and 50% or less, Tp is equal to or greater than the reference value (84%), as shown in FIG. 23(b). As a result, Tp×Rs is also equal to or greater than the reference value (76%), as shown in FIG. 23(d). Therefore, in the case of "obliquely incident light in the negative direction (θ=−45°)," it can be seen that good transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) can be obtained by adjusting Rc1 to the range of 35% or more and 50% or less.

[0452] Furthermore, it is preferable to adjust Rc1 to a range of 40% or more and 45% or less. As a result, Tp becomes 85.8% or more as shown in Figure 23(b), and Tp x Rs becomes 77% or more as shown in Figure 23(d). Therefore, it can be seen that even better transmittance (Tp characteristics) and polarization separation characteristics (Tp x Rs characteristics) can be obtained.

[0453] (2) Obliquely incident light in the positive direction (40%≦Rc1≦53%) On the other hand, when the incident direction is the "positive direction (θ=+45°)," in Example 43, if Rc1 is in the range of 40% or more and 53% or less, Tp is equal to or greater than the reference value (84%) as shown in Figure 23(b). As a result, Tp×Rs is also equal to or greater than the reference value (76%) as shown in Figure 23(d). Therefore, in the case of "obliquely incident light in the positive direction (θ=+45°)," it can be seen that good transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) can be obtained by adjusting Rc1 to the range of 40% or more and 53% or less.

[0454] Furthermore, it is preferable to adjust Rc1 to a range of 45% or more and 50% or less. As a result, Tp becomes 85% or more as shown in Figure 23(b), and Tp x Rs becomes 76.5% or more as shown in Figure 23(d). Therefore, it can be seen that even better transmittance (Tp characteristics) and polarization separation characteristics (Tp x Rs characteristics) can be obtained.

[0455] Furthermore, as shown in Figure 23(e), in both the case of "oblique incident light in the negative direction (θ = -45°)" and "oblique incident light in the positive direction (θ = +45°)", the larger the coverage rate Rc1, the higher the contrast CR.

[0456] The results of Example 43 above show that even when the coverage Rc1 varies during grid manufacturing, tilting the ridges 22 makes it possible to obtain transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) equivalent to or better than the standard (Comparative Example 40). Therefore, by changing the installation orientation of the tilted grid structure of the polarizing element 1 in accordance with the incident direction (+ direction or - direction) of obliquely incident light, it is possible to provide a polarizing element 1 that has excellent transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) for directional obliquely incident light.

[0457] (Forty-Fourth Embodiment) Next, a forty-fourth embodiment of the present invention will be described with reference to FIG.

[0458] As shown in Figure 24, a model of the polarizing element 1 according to Example 44 was fabricated. In Example 44, a grid (a structure combining the ridge portions 22 and the reflective film 30) having a special tree shape was fabricated in the same manner as in Example 40 described above, except that the coverage Rc2 of the second side surface 22b2 of the ridge portions 22 was changed. In Example 44, in order to provide a tilted grid structure, the upper portions 22c of the ridge portions 22 (the upper 50% of the ridge portions 22) were tilted at an inclination angle α to one side in the width direction of the ridge portions 22 (the right side in Figure 24(a)). The inclination angle α in Example 44 was fixed at 10°.

[0459] In Example 44, the coverage Rc of the reflective film 30 covering the protruding rib portion 22 was varied between the first side surface 22b1 and the second side surface 22b2. The first side surface 22b1 is the side surface 22b on the inclined side of the protruding rib portion 22 (the side surface on the right in FIG. 24(a)), and the second side surface 22b2 is the side surface 22b on the opposite side to the inclined side of the protruding rib portion 22 (the side surface on the left in FIG. 24(a)). In Example 44, the coverage Rc1 (= Hx1 / H) of the first side surface 22b1 was fixed at 45%, and the coverage Rc2 (= Hx2 / H) of the second side surface 22b2 was varied within a range of 35 to 55%.

[0460] The dimensions and shapes of the parts of the model of the polarizing element 1 according to Example 44 are as follows: P: 142 nm W Ｔ　　 : 17 nm W Ｂ　　 : 65 nm W ＭＡＸ : 65 nm H : 225 nm Hx1: 101 nm (fixed value) Hx2: 79 nm, 90 nm, 101 nm, 113 nm, 124 nm (variable value) Dt : 38 nm Ds : 17.5 nm (maximum value) Rc1 : 45% (fixed value) Rr1 : 55% (fixed value) Rc2 : 35%, 40%, 45%, 50%, 55% (variable value) Rr2 : 65%, 60%, 55%, 50%, 45% (variable value) θ : -45°, +45° λ : 430 to 680 nm α : 10° (fixed value)

[0461] A simulation was performed on the model of the polarizing element 1 according to Example 44 prepared as described above, and Tp, Ts, Rp, Rs, and Tp × Rs were calculated. The values ​​of Tp, Ts, Rp, and Rs were calculated for the cases of "obliquely incident light in the negative direction (θ = -45°)" and "obliquely incident light in the positive direction (θ = +45°)." The wavelength λ of the obliquely incident light was varied in the range of 430 to 680 nm, and the average values ​​of multiple Tp, Ts, Rp, and Rs calculated for obliquely incident light of each wavelength λ were used to calculate the values ​​of Tp, Ts, Rp, and Rs. The contrast (CR) of the transmitted light was also calculated by dividing Tp by Ts (CR = Tp / Ts).

[0462] The relationships between the Tp characteristics, Rs characteristics, Tp×Rs characteristics, contrast CR, and coverage Rc2 of the first side surface 22b1 for Example 44, which were determined as described above, are shown in the graphs of FIGS.

[0463] 24(c), the reflectance Rs of Example 44 maintains a high value of 90% or more in both the cases of "obliquely incident light in the negative direction (θ=−45°)" and "obliquely incident light in the positive direction (θ=+45°)," regardless of the magnitude of the coverage Rc2 (35 to 55%). Therefore, it is understood that a high Rs of 90% or more can be ensured regardless of Rc2, and excellent reflectivity (Rs characteristics) can be exhibited by the reflective film 30.

[0464] 24(b) and 24(d), the behavior of the Tp characteristics and the Tp×Rs characteristics according to the coverage Rc2 differs depending on whether the incident direction of the obliquely incident light is the "negative direction (θ=-45°)" or the "positive direction (θ=+45°)." Below, the Tp and Tp×Rs characteristics of Example 44 (α=10°) are compared with the reference value of Tp (84%) and the reference value of Tp×Rs (76%) of Comparative Example 40 (α=0°) shown in FIG. 20 described above, to evaluate the Tp and Tp×Rs characteristics of Example 44.

[0465] (1) Obliquely incident light in the negative direction (35%≦Rc2≦55%) First, when the incident direction is the "negative direction (θ=−45°)," in Example 44, if Rc2 is in the range of 35% or more and 55% or less, Tp is equal to or greater than the reference value (84%), as shown in FIG. 24(b). As a result, Tp×Rs is also equal to or greater than the reference value (76%), as shown in FIG. 24(d). Therefore, in the case of "obliquely incident light in the negative direction (θ=−45°)," it can be seen that good transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) can be obtained by adjusting Rc2 to the range of 35% or more and 55% or less.

[0466] Furthermore, it is preferable to adjust Rc2 to a range of 40% or more and 55% or less. As a result, Tp becomes 85.5% or more as shown in Figure 24(b), and Tp x Rs becomes 77% or more as shown in Figure 24(d). Therefore, it can be seen that even better transmittance (Tp characteristics) and polarization separation characteristics (Tp x Rs characteristics) can be obtained.

[0467] (2) Obliquely incident light in the positive direction (35%≦Rc2≦45%) On the other hand, when the incident direction is the "positive direction (θ=+45°)," in Example 44, if Rc2 is in the range of 35% or more and 45% or less, Tp is equal to or greater than the reference value (84%) as shown in Figure 24(b). As a result, Tp×Rs is also equal to or greater than the reference value (76%) as shown in Figure 24(d). Therefore, in the case of "obliquely incident light in the positive direction (θ=+45°)," it can be seen that good transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) can be obtained by adjusting Rc2 to the range of 35% or more and 45% or less.

[0468] Furthermore, it is preferable to adjust Rc2 to a range of 40% or more and 45% or less. As a result, Tp becomes approximately 85% as shown in Figure 24(b), and Tp x Rs becomes 76.5% or more as shown in Figure 24(d). Therefore, it can be seen that even better transmittance (Tp characteristics) and polarization separation characteristics (Tp x Rs characteristics) can be obtained.

[0469] Furthermore, as shown in FIG. 24( e), in both the cases of “oblique incident light in the negative direction (θ=−45°)” and “oblique incident light in the positive direction (θ=+45°),” the larger the coverage rate Rc2, the higher the contrast CR, and in particular, the contrast CR increases sharply at 45% or more.

[0470] The results of Example 44 above show that even when the coverage Rc2 varies during grid manufacturing, tilting the ridges 22 makes it possible to obtain transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) equivalent to or better than the standard (Comparative Example 40). Therefore, by changing the installation orientation of the tilted grid structure of the polarizing element 1 in accordance with the incident direction (+ direction or - direction) of obliquely incident light, it is possible to provide a polarizing element 1 that has excellent transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) for directional obliquely incident light.

[0471] <2. Verification results of the composition of organic material (photocurable acrylic resin for imprinting)>

[0472] Examples 51 to 58 and Comparative Examples 51 to 57 were prepared as photocurable acrylic resins for imprinting.

[0473] The viscosity was measured for the photocurable acrylic resins for imprints according to Examples 51 to 58 and Comparative Examples 51 to 57. The viscosity was measured using a Brookfield viscometer manufactured by Eiko Precision Instruments Co., Ltd. with a cone and plate.

[0474] The cured products of the photocurable acrylic resins for imprints according to Examples 51 to 58 and Comparative Examples 51 to 57 were held at 150°C for 500 hours (heat treatment) and then the YI values ​​were measured. The YI values ​​were calculated based on the results of measurements using a UV-Visible-Near-Infrared Spectrophotometer V-770 manufactured by JASCO Corporation. The measurement conditions and the method for calculating the YI values ​​were the same as those in the above embodiment.

[0475] The cured products of the photocurable acrylic resins for imprints according to Examples 51 to 58 and Comparative Examples 51 to 57 were measured for their average transmittance to light in the wavelength region of 430 nm or more and 680 nm or less before being subjected to a heat treatment (holding at 150°C for 500 hours), and for their average transmittance to light in the wavelength region of 430 nm or more and 510 nm or less. Furthermore, the cured products of the photocurable acrylic resins for imprints according to Examples 51 to 58 and Comparative Examples 51 to 57 were measured for their average transmittance to light in the wavelength region of 430 nm or more and 680 nm or less after being held at 150°C for 500 hours. The average transmittance was calculated by measuring the transmittance at 1 nm intervals in the wavelength region of 430 nm or more and 680 nm or less and simply averaging the resulting 251 measurement data points. The average transmittance was measured using an ultraviolet-visible-near infrared spectrophotometer V-770 manufactured by JASCO Corporation.

[0476] The storage moduli of the cured products of the photocurable acrylic resins for imprints according to Examples 51 to 58 and Comparative Examples 51 to 57 were measured at 30°C, 110°C, 120°C, and 130°C. The storage moduli were measured using a "DMA7100" model manufactured by Hitachi High-Technologies Corporation. Sheets of the cured products of the photocurable acrylic resins for imprints according to Examples 51 to 58 and Comparative Examples 51 to 57 were cut into pieces measuring 20 mm lengthwise and 3 mm widthwise, and the temperature was raised at a rate of 5°C / min in a tensile mode at a constant frequency (1 Hz) to measure the storage moduli from 25°C to 300°C.

[0477] The glass transition temperatures Tg were measured for the cured products of the photocurable acrylic resins for imprinting according to Examples 51 to 58 and Comparative Examples 51 to 57. The glass transition temperatures Tg were measured using a "DMA7100" model manufactured by Hitachi High-Tech Corporation. Sheets of the cured products of the photocurable acrylic resins for imprinting according to Examples 51 to 58 and Comparative Examples 51 to 57 were cut into pieces of 20 mm length x 3 mm width, and the temperature was raised at a rate of 5°C / min in a tensile mode at a constant frequency (1 Hz) to measure the maximum value of the loss tangent tanδ from 25°C to 300°C.

[0478] The compositions and viscosities of the photocurable acrylic resins for imprints of Examples 51 to 54 are shown in Table 1 below. The YI values, average transmittance, storage modulus, and glass transition temperatures Tg of the cured products of the photocurable acrylic resins for imprints of Examples 51 to 54 are shown in Table 2 below.

[0479] The compositions and viscosities of the photocurable acrylic resins for imprints of Examples 55 to 58 are shown in Table 3 below. The YI values, average transmittance, storage modulus, and glass transition temperatures Tg of the cured products of the photocurable acrylic resins for imprints of Examples 55 to 58 are shown in Table 4 below.

[0480] The compositions and viscosities of the photocurable acrylic resins for imprinting of Comparative Examples 51 to 54 are shown in Table 5 below. The YI values, average transmittance, storage modulus, and glass transition temperatures Tg of the cured products of the photocurable acrylic resins for imprinting of Comparative Examples 51 to 54 are shown in Table 6 below.

[0481] The compositions and viscosities of the photocurable acrylic resins for imprints of Comparative Examples 55 to 57 are shown in Table 7 below. The YI values, average transmittance, storage modulus, and glass transition temperatures Tg of the cured products of the photocurable acrylic resins for imprints of Comparative Examples 55 to 57 are shown in Table 8 below.

[0482] The units of content in Tables 1, 3, 5, and 7 are % by mass. The viscosities in Tables 1, 3, 5, and 7 are measured in mPa·s at 25°C.

[0483]

[0484]

[0485] Example 51 As shown in Table 1, Example 51 contained only resin (A), resin (B), and resin (C) as photopolymerizable components, and further contained a photopolymerization initiator. Phenylethyl acrylate (PEA) was used as resin (A). Osaka Organic Chemical Industry Co., Ltd.'s Viscoat #192HP product was used as phenylethyl acrylate. Resin (B) used was 2,2-dimethylethylene bis(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate and 1,6-hexanediol diacrylate. Nippon Kayaku Co., Ltd.'s KAYARAD R-604 product was used as 2,2-dimethylethylene bis(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate. Shin-Nakamura Chemical Co., Ltd.'s A-HD-N product was used as 1,6-hexanediol diacrylate. Dipentaerythritol hexaacrylate (DPHA) was used as resin (C). Dipentaerythritol hexaacrylate was used under the product name "KAYARAD DPHA" manufactured by Nippon Kayaku Co., Ltd. The photopolymerization initiator was "Irgacure 819" manufactured by IGM Resins B.V. In Example 51, the content of resin (A) in the entire photopolymerization components was 33% by mass, the content of resin (B) was 66% by mass, and the content of resin (C) was 1% by mass. In Example 51, the ratio of 1,6-hexanediol diacrylate to (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate in resin (B) was 1:1. In Example 51, the content of the photopolymerization initiator was 0.5% by mass when the content of the entire photopolymerization components was 100% by mass.

[0486] As shown in Table 1, the viscosity of the photocurable acrylic resin for imprints in Example 51 was 12.32 mPa·s.

[0487] As shown in Table 2, the YI value after heat treatment of the cured product of the photocurable acrylic resin for imprints of Example 51 was 1.1. These results confirmed that the cured product of Example 51 could maintain a low YI value even when heat treated at 150°C.

[0488] As shown in Table 2, the cured product of the photocurable acrylic resin for imprints of Example 51 had an average transmittance of 91.9% for light in the wavelength region of 430 nm or more and 680 nm or less before heat treatment, and an average transmittance of 91.7% for light in the wavelength region of 430 nm or more and 510 nm or less before heat treatment. Furthermore, the cured product of the photocurable acrylic resin for imprints of Example 51 had an average transmittance of 92.1% for light in the wavelength region of 430 nm or more and 680 nm or less after heat treatment, and an average transmittance of 91.6% for light in the wavelength region of 430 nm or more and 510 nm or less after heat treatment.

[0489] For the cured product of Example 51, the difference ΔA in average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less before and after heat treatment (average transmittance before heat treatment - average transmittance after heat treatment) was -0.2%. For the cured product of Example 51, the difference ΔA in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less before and after heat treatment was +0.1%. From these results, it was confirmed that even when the cured product of Example 51 was subjected to heat treatment at 150°C, there was almost no decrease in the average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less and the average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less.

[0490] As shown in Table 2, the storage modulus at 30°C of the cured product of the photocurable acrylic resin for imprints of Example 51 was 2.0 × 10 ９ The storage modulus at 110°C of the cured product of the photocurable acrylic resin for imprints in Example 51 was 1.3 × 10 ８ The storage modulus at 120°C of the cured product of the photocurable acrylic resin for imprints in Example 51 was 1.3 × 10 ８ The storage modulus at 130°C of the cured product of the photocurable acrylic resin for imprints in Example 51 was 1.4 × 10 ８ From the above results, it can be seen that the cured product of Example 51 had a viscosity of 2.0 × 10 ９It was confirmed that the cured product of Example 51 had a high storage modulus of 100 Pa. It was also confirmed that even when the cured product of Example 51 was subjected to a heat treatment at 150°C, the decrease in storage modulus was suppressed.

[0491] As shown in Table 2, the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 51 was 70.7° C. From the above results, it was confirmed that, despite having a glass transition temperature Tg of less than 110° C., the cured product of Example 51 was able to keep the YI value low after heat treatment at 150° C., maintain a high average transmittance after heat treatment at 150° C., and further suppress a decrease in storage modulus after heat treatment at 150° C.

[0492] Example 52 As shown in Table 1, Example 52 differs from Example 51 only in the content of resins (A) to (C). In Example 52, the content of resin (A) in the entire photopolymerizable components was 30% by mass, the content of resin (B) was 60% by mass, and the content of resin (C) was 10% by mass. Also in Example 52, the ratio of 1,6-hexanediol diacrylate to (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate in resin (B) was 1:1.

[0493] As shown in Table 1, the viscosity of the photocurable acrylic resin for imprinting of Example 52 was 20.54 mPa s. The photocurable acrylic resin for imprinting of Example 52 also had a higher content of resin (C) than the photocurable acrylic resin for imprinting of Example 51. This is presumably why the viscosity of the photocurable acrylic resin for imprinting of Example 52 was higher than that of the photocurable acrylic resin for imprinting of Example 51.

[0494] As shown in Table 2, the YI value of the cured product of the photocurable acrylic resin for imprints of Example 52 after heat treatment was 1.6. These results confirm that the cured product of Example 52 can maintain a low YI value even when heat treated at 150°C. Furthermore, the photocurable acrylic resin for imprints of Example 52 has a higher resin (C) content than the photocurable acrylic resin for imprints of Example 51. This is presumably why the YI value of the cured product of the photocurable acrylic resin for imprints of Example 52 was higher than the YI value of the cured product of the photocurable acrylic resin for imprints of Example 51.

[0495] As shown in Table 2, the cured product of the photocurable acrylic resin for imprints of Example 52 had an average transmittance of 91.9% for light in the wavelength region of 430 nm or more and 680 nm or less before heat treatment, and an average transmittance of 91.8% for light in the wavelength region of 430 nm or more and 510 nm or less before heat treatment. Furthermore, the cured product of the photocurable acrylic resin for imprints of Example 52 had an average transmittance of 91.8% for light in the wavelength region of 430 nm or more and 680 nm or less after heat treatment, and an average transmittance of 91.0% for light in the wavelength region of 430 nm or more and 510 nm or less after heat treatment.

[0496] For the cured product of Example 52, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less before and after heat treatment was +0.1%. For the cured product of Example 52, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less before and after heat treatment was +0.8%. From these results, it was confirmed that even when the cured product of Example 52 was heat treated at 150°C, there was almost no decrease in the average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less, and the average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less. Furthermore, the photocurable acrylic resin for imprints of Example 52 had a higher content of resin (C) than the photocurable acrylic resin for imprints of Example 51. It is therefore presumed that the difference ΔA in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less of the cured product of the photocurable acrylic resin for imprints in Example 52 was slightly larger than the difference ΔA in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less of the cured product of the photocurable acrylic resin for imprints in Example 51.

[0497] As shown in Table 2, the storage modulus at 30°C of the cured product of the photocurable acrylic resin for imprints of Example 52 was 3.1 × 10 ９ The storage modulus at 110°C of the cured product of the photocurable acrylic resin for imprints of Example 52 was 5.1 × 10 ８ The storage modulus at 120°C of the cured product of the photocurable acrylic resin for imprints of Example 52 was 3.9 × 10 ８ The storage modulus at 130°C of the cured product of the photocurable acrylic resin for imprints of Example 52 was 3.3 × 10 ８ From the above results, it can be seen that the cured product of Example 52 had a viscosity of 3.1 × 10 Pa before the heat treatment. ９It was confirmed that the cured product of Example 52 had a high storage modulus of 100 Pa. It was also confirmed that even when the cured product of Example 52 was subjected to a heat treatment at 150°C, a decrease in storage modulus was suppressed. The photocurable acrylic resin for imprinting of Example 52 also had a higher content of resin (C) than the photocurable acrylic resin for imprinting of Example 51. This is presumably why the storage modulus of the cured product of the photocurable acrylic resin for imprinting of Example 52 was higher than that of the cured product of the photocurable acrylic resin for imprinting of Example 51.

[0498] As shown in Table 2, the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 52 was 103.1° C. From the above results, it was confirmed that, despite having a glass transition temperature Tg of less than 110° C., the cured product of Example 52 was able to keep the YI value low after heat treatment at 150° C., maintain a high average transmittance after heat treatment at 150° C., and further suppress a decrease in storage modulus after heat treatment at 150° C.

[0499] Example 53 As shown in Table 1, Example 53 differs from Examples 51 and 52 only in the content of resins (A) to (C). In Example 53, the content of resin (A) in the entire photopolymerizable components was 23.3 mass%, the content of resin (B) was 46.7 mass%, and the content of resin (C) was 30 mass%. Also in Example 53, the ratio of 1,6-hexanediol diacrylate to (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate in resin (B) was 1:1.

[0500] As shown in Table 1, the viscosity of the photocurable acrylic resin for imprinting of Example 53 was 68.12 mPa s. The photocurable acrylic resin for imprinting of Example 53 also had a higher content of resin (C) than the photocurable acrylic resin for imprinting of Example 52. This is presumably why the viscosity of the photocurable acrylic resin for imprinting of Example 53 was higher than that of the photocurable acrylic resin for imprinting of Example 52.

[0501] As shown in Table 2, the YI value of the cured product of the photocurable acrylic resin for imprints of Example 53 after heat treatment was 2.3. These results confirm that the cured product of Example 53 can maintain a low YI value even when heat treated at 150°C. Furthermore, the photocurable acrylic resin for imprints of Example 53 has a higher resin (C) content than the photocurable acrylic resin for imprints of Example 52. This is presumably why the YI value of the cured product of the photocurable acrylic resin for imprints of Example 53 was higher than the YI value of the cured product of the photocurable acrylic resin for imprints of Example 52.

[0502] As shown in Table 2, the cured product of the photocurable acrylic resin for imprints of Example 53 had an average transmittance of 92.0% for light in the wavelength region of 430 nm or more and 680 nm or less before heat treatment, and an average transmittance of 91.8% for light in the wavelength region of 430 nm or more and 510 nm or less before heat treatment. Furthermore, the cured product of the photocurable acrylic resin for imprints of Example 53 had an average transmittance of 91.8% for light in the wavelength region of 430 nm or more and 680 nm or less after heat treatment, and an average transmittance of 90.7% for light in the wavelength region of 430 nm or more and 510 nm or less after heat treatment.

[0503] For the cured product of Example 53, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less before and after heat treatment was +0.2%. For the cured product of Example 53, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less before and after heat treatment was +1.1%. From these results, it was confirmed that even when the cured product of Example 53 was heat treated at 150°C, there was almost no decrease in the average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less, and the average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less. Furthermore, the photocurable acrylic resin for imprints of Example 53 had a higher content of resin (C) than the photocurable acrylic resin for imprints of Example 52. It is presumed that this is the reason why the difference ΔA in average transmittance of the cured product of the photocurable acrylic resin for imprints in Example 53 was larger than the difference ΔA in average transmittance of the cured product of the photocurable acrylic resin for imprints in Example 52.

[0504] As shown in Table 2, the storage modulus at 30°C of the cured product of the photocurable acrylic resin for imprints in Example 53 was 3.2 × 10 ９ The storage modulus at 110°C of the cured product of the photocurable acrylic resin for imprints in Example 53 was 1.1 × 10 ９ The storage modulus at 120°C of the cured product of the photocurable acrylic resin for imprints of Example 53 was 9.1 × 10 ８ The storage modulus at 130°C of the cured product of the photocurable acrylic resin for imprints of Example 53 was 8.0 × 10 ８ From the above results, it can be seen that the cured product of Example 53 had a viscosity of 3.2 × 10 Pa before the heat treatment. ９It was confirmed that the cured product of Example 53 had a high storage modulus of 100 Pa. It was also confirmed that even when the cured product of Example 53 was subjected to a heat treatment at 150°C, the decrease in storage modulus was suppressed. The photocurable acrylic resin for imprinting of Example 53 also had a higher content of resin (C) than the photocurable acrylic resin for imprinting of Example 52. This is presumably why the storage modulus of the cured product of the photocurable acrylic resin for imprinting of Example 53 was higher than that of the cured product of the photocurable acrylic resin for imprinting of Example 52.

[0505] As shown in Table 2, the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 53 was 103.8° C. From the above results, it was confirmed that, despite having a glass transition temperature Tg of less than 110° C., the cured product of Example 53 was able to keep the YI value low after heat treatment at 150° C., maintain a high average transmittance after heat treatment at 150° C., and suppress a decrease in storage modulus after further heat treatment at 150° C.

[0506] Example 54 As shown in Table 1, Example 54 differs from Examples 51 to 53 only in the content of resins (A) to (C). In Example 54, the content of resin (A) in the entire photopolymerization component was 42% by mass, the content of resin (B) was 43% by mass, and the content of resin (C) was 15% by mass. In addition, in Example 54, the content of 1,6-hexanediol diacrylate in resin (B) was 42% by mass, and the content of (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate was 1% by mass.

[0507] As shown in Table 1, the viscosity of the photocurable acrylic resin for imprints of Example 54 was 13.45 mPa s. Furthermore, the photocurable acrylic resin for imprints of Example 54 had a higher content of 1,6-hexanediol diacrylate than those of Examples 52 and 53. This is presumably why the viscosity of the photocurable acrylic resin for imprints of Example 54 was lower than those of the photocurable acrylic resins for imprints of Examples 52 and 53.

[0508] As shown in Table 2, the YI value of the cured product of the photocurable acrylic resin for imprints of Example 54 after heat treatment was 1.4. These results confirm that the cured product of Example 54 can maintain a low YI value even when heat treated at 150°C. Furthermore, the photocurable acrylic resin for imprints of Example 54 has a higher content of 1,6-hexanediol diacrylate than those of Examples 52 and 53. This is presumably why the YI value of the cured product of the photocurable acrylic resin for imprints of Example 54 was lower than the YI values ​​of the cured products of the photocurable acrylic resins for imprints of Examples 52 and 53.

[0509] As shown in Table 2, the cured product of the photocurable acrylic resin for imprints of Example 54 had an average transmittance of 91.8% for light in the wavelength region of 430 nm or more and 680 nm or less before heat treatment, and an average transmittance of 91.6% for light in the wavelength region of 430 nm or more and 510 nm or less before heat treatment. Furthermore, the cured product of the photocurable acrylic resin for imprints of Example 54 had an average transmittance of 91.9% for light in the wavelength region of 430 nm or more and 680 nm or less after heat treatment, and an average transmittance of 91.3% for light in the wavelength region of 430 nm or more and 510 nm or less after heat treatment.

[0510] For the cured product of Example 54, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less before and after heat treatment was -0.1%. For the cured product of Example 54, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less before and after heat treatment was +0.3%. From these results, it was confirmed that even when the cured product of Example 54 was heat treated at 150°C, there was almost no decrease in the average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less, and the average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less. Furthermore, the photocurable acrylic resin for imprints of Example 54 had a higher content of 1,6-hexanediol diacrylate than Examples 52 and 53. It is presumed that this is the reason why the difference ΔA in average transmittance between the cured products of the photocurable acrylic resin for imprinting in Example 54 was smaller than the differences ΔA in average transmittance between the cured products of the photocurable acrylic resin for imprinting in Examples 52 and 53.

[0511] As shown in Table 2, the storage modulus at 30°C of the cured product of the photocurable acrylic resin for imprints in Example 54 was 2.3 × 10 ９ The storage modulus at 110°C of the cured product of the photocurable acrylic resin for imprints in Example 54 was 1.9 × 10 ８ The storage modulus at 120°C of the cured product of the photocurable acrylic resin for imprints in Example 54 was 2.2 × 10 ８ The storage modulus at 130°C of the cured product of the photocurable acrylic resin for imprints in Example 54 was 2.3 × 10 ８ From the above results, it can be seen that the cured product of Example 54 had a viscosity of 2.3 × 10 Pa before the heat treatment. ９It was confirmed that the cured product of Example 54 had a high storage modulus of 100 Pa. It was also confirmed that even when the cured product of Example 54 was subjected to a heat treatment at 150°C, the decrease in storage modulus was suppressed. The photocurable acrylic resin for imprints of Example 54 also had a higher content of resin (C) than that of Example 51. It is presumed that this is why the storage modulus of the cured product of the photocurable acrylic resin for imprints of Example 54 was higher than that of the cured product of the photocurable acrylic resin for imprints of Example 51.

[0512] As shown in Table 2, the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 54 was 58.0°C. These results confirm that, despite having a glass transition temperature Tg of less than 110°C, the cured product of Example 54 was able to maintain a low YI value after heat treatment at 150°C, maintain a high average transmittance after heat treatment at 150°C, and suppress a decrease in storage modulus after heat treatment at 150°C. Furthermore, the photocurable acrylic resin for imprints of Example 54 had a higher content of 1,6-hexanediol diacrylate than those of Examples 52 and 53. This is presumably why the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 54 was lower than the glass transition temperatures Tg of the cured products of the photocurable acrylic resins for imprints of Examples 52 and 53.

[0513]

[0514]

[0515] Example 55 As shown in Table 3, Example 55 differs from Example 54 only in the contents of 1,6-hexanediol diacrylate and (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate in resin (B). In Example 55, the content of 1,6-hexanediol diacrylate in resin (B) was 1 mass %, and the content of (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate was 42 mass %.

[0516] As shown in Table 3, the viscosity of the photocurable acrylic resin for imprints of Example 55 was 85.01 mPa s. Furthermore, the photocurable acrylic resin for imprints of Example 55 had a lower content of 1,6-hexanediol diacrylate and a higher content of (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate compared to Example 54. This is presumably why the viscosity of the photocurable acrylic resin for imprints of Example 55 was higher than that of the photocurable acrylic resin for imprints of Example 54.

[0517] As shown in Table 4, the YI value after heat treatment of the cured product of the photocurable acrylic resin for imprints of Example 55 was 1.1. These results confirm that the cured product of Example 55 can maintain a low YI value even when heat treated at 150°C.

[0518] As shown in Table 4, the cured product of the photocurable acrylic resin for imprints of Example 55 had an average transmittance of 91.9% for light in the wavelength region of 430 nm or more and 680 nm or less before heat treatment, and an average transmittance of 91.7% for light in the wavelength region of 430 nm or more and 510 nm or less before heat treatment. Furthermore, the cured product of the photocurable acrylic resin for imprints of Example 55 had an average transmittance of 92.0% for light in the wavelength region of 430 nm or more and 680 nm or less after heat treatment, and an average transmittance of 91.5% for light in the wavelength region of 430 nm or more and 510 nm or less after heat treatment.

[0519] For the cured product of Example 55, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less before and after heat treatment was -0.2%. For the cured product of Example 55, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less before and after heat treatment was +0.1%. From these results, it was confirmed that even when the cured product of Example 55 was subjected to heat treatment at 150°C, there was almost no decrease in the average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less and the average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less.

[0520] As shown in Table 4, the storage modulus at 30°C of the cured product of the photocurable acrylic resin for imprints in Example 55 was 2.6 × 10 ９ The storage modulus at 110°C of the cured product of the photocurable acrylic resin for imprints in Example 55 was 1.5 × 10 ８ The storage modulus at 120°C of the cured product of the photocurable acrylic resin for imprints of Example 55 was 1.4 × 10 ８ The storage modulus at 130°C of the cured product of the photocurable acrylic resin for imprints in Example 55 was 1.4 × 10 ８ From the above results, it can be seen that the cured product of Example 55 had a viscosity of 2.6 × 10 Pa before the heat treatment. ９ It was confirmed that the cured product of Example 55 had a high storage modulus of 100 Pa. It was also confirmed that even when the cured product of Example 55 was subjected to a heat treatment at 150°C, the decrease in storage modulus was suppressed.

[0521] As shown in Table 4, the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 55 was 70.1°C. These results confirm that, despite having a glass transition temperature Tg of less than 110°C, the cured product of Example 55 was able to maintain a low YI value after heat treatment at 150°C, maintain a high average transmittance after heat treatment at 150°C, and suppress a decrease in storage modulus after heat treatment at 150°C. Furthermore, the photocurable acrylic resin for imprints of Example 55 had a higher content of (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate than the photocurable acrylic resin for imprints of Example 54. This presumably explains why the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 55 was higher than the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 54.

[0522] Example 56 As shown in Table 3, Example 56 contained only resin (A), resin (B), and resin (C) as photopolymerizable components, and further contained a photopolymerization initiator. Phenylethyl acrylate (PEA) was used as resin (A). Osaka Organic Chemical Industry Co., Ltd.'s Viscoat #192HP product was used as phenylethyl acrylate. Resin (B) included (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate and 1,6-hexanediol diacrylate. Nippon Kayaku Co., Ltd.'s KAYARAD R-684 product was used as (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate. Shin-Nakamura Chemical Co., Ltd.'s A-HD-N product was used as 1,6-hexanediol diacrylate. Dipentaerythritol hexaacrylate (DPHA) was used as resin (C). Dipentaerythritol hexaacrylate was used under the product name "KAYARAD DPHA" manufactured by Nippon Kayaku Co., Ltd. The photopolymerization initiator was "Irgacure 819" manufactured by IGM Resins B.V. In Example 56, the content of resin (A) in the entire photopolymerization components was 20% by mass, the content of resin (B) was 60% by mass, and the content of resin (C) was 20% by mass. In Example 56, the ratio of 1,6-hexanediol diacrylate to (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate in resin (B) was 1:1. In Example 56, the content of the photopolymerization initiator was 0.5% by mass when the content of the entire photopolymerization components was 100% by mass.

[0523] As shown in Table 3, the viscosity of the photocurable acrylic resin for imprints in Example 56 was 26.20 mPa·s.

[0524] As shown in Table 4, the YI value after heat treatment of the cured product of the photocurable acrylic resin for imprints of Example 56 was 2.3. These results confirm that the cured product of Example 56 can maintain a low YI value even when heat treated at 150°C.

[0525] As shown in Table 4, the cured product of the photocurable acrylic resin for imprints of Example 56 had an average transmittance of 91.7% for light in the wavelength region of 430 nm or more and 680 nm or less before heat treatment, and an average transmittance of 91.5% for light in the wavelength region of 430 nm or more and 510 nm or less before heat treatment. Furthermore, the cured product of the photocurable acrylic resin for imprints of Example 56 had an average transmittance of 91.1% for light in the wavelength region of 430 nm or more and 680 nm or less after heat treatment, and an average transmittance of 90.0% for light in the wavelength region of 430 nm or more and 510 nm or less after heat treatment.

[0526] For the cured product of Example 56, the difference ΔA in average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less before and after heat treatment (average transmittance before heat treatment - average transmittance after heat treatment) was +0.6%. For the cured product of Example 56, the difference ΔA in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less before and after heat treatment was +1.5%. From these results, it was confirmed that even when the cured product of Example 56 was subjected to heat treatment at 150°C, there was almost no decrease in the average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less and the average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less.

[0527] As shown in Table 4, the storage modulus at 30°C of the cured product of the photocurable acrylic resin for imprints in Example 56 was 3.0 × 10 ９ The storage modulus at 110°C of the cured product of the photocurable acrylic resin for imprints in Example 56 was 1.0 × 10 ９ The storage modulus at 120°C of the cured product of the photocurable acrylic resin for imprints of Example 56 was 8.6 × 10 ８ The storage modulus at 130°C of the cured product of the photocurable acrylic resin for imprints of Example 56 was 7.4 × 10 ８ From the above results, it can be seen that the cured product of Example 56 had a viscosity of 3.0 × 10 Pa before the heat treatment. ９It was confirmed that the cured product of Example 56 had a high storage modulus of 100 Pa. It was also confirmed that even when the cured product of Example 56 was subjected to a heat treatment at 150°C, the decrease in storage modulus was suppressed.

[0528] As shown in Table 4, the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprints of Example 56 was 109.3° C. From the above results, it was confirmed that, despite having a glass transition temperature Tg of less than 110° C., the cured product of Example 56 was able to keep the YI value low after heat treatment at 150° C., maintain a high average transmittance after heat treatment at 150° C., and further suppress a decrease in storage modulus after heat treatment at 150° C.

[0529] [Example 57] As shown in Table 3, Example 57 differs from Example 52 only in the resin (C). In Example 57, tris-(2-acryloxyethyl) isocyanurate was used as the resin (C). The tris-(2-acryloxyethyl) isocyanurate used was "A-9300S," a product manufactured by Shin-Nakamura Chemical Co., Ltd.

[0530] As shown in Table 3, the viscosity of the photocurable acrylic resin for imprints in Example 57 was 20.47 mPa s. There was almost no difference in viscosity between Examples 52 and 57, which indicates that the photocurable acrylic resins for imprints had low viscosities even though the resin (C) was a different substance.

[0531] As shown in Table 4, the YI value of the cured product of Example 57 was 1.0. These results confirmed that the cured product of Example 57 could maintain a low YI value even when subjected to a heat treatment at 150°C. Furthermore, since there was almost no difference in the YI values ​​of the cured products of Examples 52 and 57, it was found that the cured products of the photocurable acrylic resin for imprints could maintain a low YI value even when the resin (C) was a different substance.

[0532] As shown in Table 4, the cured product of the photocurable acrylic resin for imprints of Example 57 had an average transmittance of 91.9% for light in the wavelength region of 430 nm or more and 680 nm or less before heat treatment, and an average transmittance of 91.7% for light in the wavelength region of 430 nm or more and 510 nm or less before heat treatment. Furthermore, the cured product of the photocurable acrylic resin for imprints of Example 57 had an average transmittance of 91.8% for light in the wavelength region of 430 nm or more and 680 nm or less after heat treatment, and an average transmittance of 91.4% for light in the wavelength region of 430 nm or more and 510 nm or less after heat treatment. The fact that there was almost no difference in the average transmittance between the cured products of Examples 52 and 57 demonstrated that the cured products of the photocurable acrylic resin for imprints were able to maintain a high average transmittance even when the resin (C) was a different substance.

[0533] For the cured product of Example 57, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less before and after heat treatment was +0.1%. For the cured product of Example 57, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less before and after heat treatment was +0.4%. From these results, it was confirmed that even when the cured product of Example 57 was subjected to a heat treatment at 150°C, there was almost no decrease in average transmittance for light in the wavelength region of 430 nm or more and 680 nm or less, and the average transmittance for light in the wavelength region of 430 nm or more and 510 nm or less. Furthermore, since there was almost no difference in the difference ΔA in average transmittance for the cured product of Example 52 and the cured product of Example 57, it was found that even when the resin (C) was a different substance, there was almost no decrease in average transmittance for the cured product of the photocurable acrylic resi...

Claims

1. A wire grid polarizer comprising: a substrate made of an inorganic material; a grid structure made of an organic material, the grid structure having a base portion provided on the substrate and a plurality of ridge portions protruding from the base portion integrally formed therewith; and a functional film made of a metal material covering a portion of the ridge portions, wherein the organic material is a cured product of a photocurable acrylic resin for imprinting containing a photopolymerization component, the photopolymerization component containing: resin (A) and resin (B), the resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, and the resin (B) is a bifunctional compound, the content of the resin (A) relative to the entire photopolymerization components is 20% by mass or more and 42% by mass or less, and the content of the resin (B) relative to the entire photopolymerization components is 43% by mass or more and 66% by mass or less.

2. The wire grid polarization element described in claim 1, wherein the photopolymerization component further contains a resin (C), the resin (C) is an acrylate monomer having three or more functional groups, and the content of the resin (C) relative to the entire photopolymerization component is 1 mass % or more and 30 mass % or less.

3. A wire grid polarizer according to claim 1 or 2, wherein the resin (A) is one or both of phenylethyl acrylate and benzyl acrylate.

4. The wire grid polarization element of claim 1 or 2, wherein the resin (B) is one or more selected from the group consisting of (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate, (2,2-dimethylethylene)bis(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate, and 1,6-hexanediol diacrylate.

5. The wire grid polarizer of claim 4, wherein the resin (B) contains one of 1,6-hexanediol diacrylate, (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate, and (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene bisacrylate.

6. The wire grid polarizer according to claim 2, wherein the resin (C) contains one or both of dipentaerythritol hexaacrylate and tris-(2-acryloxyethyl)isocyanurate.

7. A wire grid polarization element according to claim 1 or 2, wherein the viscosity of the photocurable acrylic resin for imprinting at 25°C is 90 mPa·s or less.

8. The wire grid polarization element according to claim 1 or 2, wherein after the cured product of the photocurable acrylic resin for imprinting is held at 150°C for 500 hours, the YI value of the cured product is 3.0 or less.

9. The storage modulus of the cured product of the photocurable acrylic resin for imprints at 30° C. is 2.0×10 ９ The storage modulus of the cured product at 120°C is 1.3 x 10 ８ The wire grid polarization element according to claim 1 , wherein the modulus is 1 Pa or more.

10. The storage modulus of the cured product at 130°C is 1.4 x 10 ８ The wire grid polarizer according to claim 9 , wherein the linear modulus is equal to or greater than Pa.

11. The wire grid polarization element described in claim 1 or 2, wherein, after maintaining the cured product of the photocurable acrylic resin for imprinting at 150°C for 500 hours, the cured product has an average transmittance of 91% or more for light in a wavelength range of 430 nm or more and 680 nm or less, and the cured product has an average transmittance of 90% or more for light in a wavelength range of 430 nm or more and 510 nm or less.

12. A wire grid polarization element as described in claim 1 or 2, wherein the convex rib portion has a tapered shape whose width narrows as it moves away from the base portion, the functional film covers the tip and the upper side of at least one of the side surfaces of the convex rib portion, but does not cover the lower sides of both side surfaces of the convex rib portion or the base portion, and when the coverage rate (Rc) of the side surface of the convex rib portion by the functional film is the ratio of the height (Hx) of the portion of the side surface of the convex rib portion covered by the functional film to the height (H) of the convex rib portion, the coverage rate (Rc) is 30% or more and 70% or less.

13. A wire grid polarization element as described in claim 1 or 2, wherein at least the portion of the convex ridge portion that is covered with the functional film is inclined at an inclination angle (α) of more than 0° and not more than 15° with respect to the normal direction of the substrate.

14. A wire grid polarization element as described in claim 13, wherein the convex rib portion is bent midway in the height direction of the convex rib portion, and the portion of the convex rib portion above the bent position is inclined at the inclination angle (α) with respect to the normal direction of the substrate.

15. The wire grid polarizer according to claim 13, wherein the entirety of the convex rib portion is inclined at the inclination angle (α) with respect to the normal direction of the substrate.

16. The wire grid polarizer of claim 13, wherein the tilt angle (α) is greater than or equal to 5° and less than or equal to 10°.

17. A wire grid polarization element as described in claim 13, wherein the functional film covers the tip and upper sides of both sides of the convex rib portion, and the coverage rate (Rc) of the both sides of the convex rib portion by the functional film is 30% or more and 70% or less.

18. A wire grid polarization element as described in claim 17, wherein the coverage (Rc) of the first side surface of the convex rib portion on the inclined side of the convex rib portion is 35% or more and 50% or less.

19. The wire grid polarizer of claim 18, wherein the coverage (Rc) of the first side is greater than or equal to 40% and less than or equal to 53%.

20. A wire grid polarization element as described in claim 17, wherein the coverage (Rc) of a second side surface of the convex rib portion opposite the inclined side of the convex rib portion is 35% or more and 55% or less.

21. The wire grid polarizer of claim 20, wherein the coverage (Rc) of the second side is greater than or equal to 35% and less than or equal to 45%.

22. A method for manufacturing a wire-grid polarization element as defined in claim 1 or 2, comprising the steps of: forming a grid structure material made of an organic material on a substrate made of an inorganic material; forming a grid structure having a base portion provided on the substrate and a plurality of ridge portions protruding from the base portion by nanoimprinting the grid structure material; and forming a functional film using a metal material to cover a portion of the ridge portions, wherein the organic material is a cured product of a photocurable acrylic resin for imprinting containing a photopolymerizable component, the photopolymerizable component comprising: resin (A) and resin (B), the resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, and the resin (B) is a bifunctional compound, the content of the resin (A) relative to the entire photopolymerizable components is 20% by mass or more and 42% by mass or less, and the content of the resin (B) relative to the entire photopolymerizable components is 43% by mass or more and 66% by mass or less.

23. A method for manufacturing a wire grid polarization element as described in claim 22, wherein the photocurable acrylic resin for imprinting further contains a photopolymerization initiator for polymerizing the photopolymerization component, and the process for forming the grid structure includes: mixing the resin (A) and the resin (B); and mixing the photopolymerization initiator into the mixed resin of the resin (A) and the resin (B).

24. The method for manufacturing a wire grid polarization element described in claim 22, wherein the photopolymerization component further contains a resin (C), which is an acrylate monomer having three or more functional groups, and a content of the resin (C) relative to the entire photopolymerization component is 1 mass % or more and 30 mass % or less, and the step of forming the grid structure includes: mixing the resin (A) and the resin (B) to generate a first mixed resin; and mixing the resin (C) with the first mixed resin to generate a second mixed resin.

25. A projection display device comprising: a light source; a polarizing beam splitter arranged so that light from the light source is incident at an angle of incidence of 30° or more and 60° or less, and separating the incident light into a first polarized light and a second polarized light; a reflective liquid crystal display element arranged so that the first polarized light reflected by the polarizing beam splitter or the second polarized light transmitted through the polarizing beam splitter is incident and reflects and modulates the incident first polarized light or the second polarized light; and a lens arranged so that the first polarized light or the second polarized light reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter, wherein the polarizing beam splitter is constituted by the wire grid polarization element described in claim 1 or 2.

26. A vehicle equipped with a projection display device according to claim 25.

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