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

Abstract

To provide a wire grid polarization element which is excellent in heat resistance.SOLUTION: A wire grid polarization element 1 includes: a substrate 10 composed of an inorganic material; a grid structure 20 that is composed of an organic material, in which a base part 21 and a plurality of protrusion parts 22 provided on the substrate 10 are integrally formed; and a resin film 30 which is composed of a metal material, and coats a part of the protrusion parts 22. The organic material is a cured product of photocurable acrylic resin for imprint containing a photopolymerization component, the photopolymerization component contains 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, the resin (B) is a bifunctional compound, a percentage content of the resin (A) to the total photopolymerization component is 20 mass% or more and 42 mass% or less, and a percentage content of the resin (B) to the total photopolymerization component is 43 mass% or more and 66 mass% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wire grid polarizing element having good polarization characteristics, not causing deterioration of heat dissipation and manufacturing cost, excellent in permeability to incident light from an oblique direction and incident light with a wide range of incident angles, a method for manufacturing the wire grid polarizing element, a projection display device excellent in polarization characteristics and heat resistance, and a vehicle equipped with the projection display device.

Background Art

[0002] As one of projection display devices, in recent years, many vehicle head-up display devices that display images on a semi-transmissive plate such as a front glass or a combiner of a vehicle (hereinafter, collectively referred to as a "display surface") have been developed. A vehicle head-up display device is, for example, a video display device disposed on a dashboard of a vehicle, projecting video light onto a front glass, and displaying driving information as a virtual image. Since a driver can visually recognize the virtual image simultaneously with the scenery through the front glass, there is an advantage that the movement of the driver's line of sight is small as compared with a conventional display device such as a liquid crystal display installed outside the range of the front glass.

[0003] However, since the above-described head-up display device emits a display image from below toward the front glass surface (above), sunlight may enter in the direction opposite to the emission direction of the display image and enter the display element. In a head-up display device, a reflector for reflecting and enlarging a display image is often provided for the purpose of miniaturization and enlargement of the display image. In such a case, the sunlight incident on the head-up display device is condensed near the display element, which may cause deterioration or failure of the display element due to heat.

[0004] Therefore, for the purpose of preventing sunlight from entering the display element, a technique of providing a reflective polarizing element in a head-up display device has been developed. For example, Patent Document 1 discloses a head-up display device provided with a reflective polarizing element (wire grid polarizing plate) between a reflector and a display element.

[0005] Here, examples of the polarizing element provided in the head-up display device as described above include a polarizing element made of a birefringent resin, a wire grid type polarizing element in which a plurality of conductors (metal fine wires) extend in parallel on a transparent substrate, a polarizing element made of a cholesteric liquid crystal, and the like. Among these, wire grid type polarizing elements with excellent polarization characteristics are widely used. In a wire grid type polarizing element, a wire grid is formed in which conductor lines made of metal or the like are arranged in a lattice pattern at a specific pitch. By setting the arrangement pitch of the wire grid to be smaller (for example, 1 / 2 or less) than the wavelength of incident light (for example, visible light), light with an electric field vector component vibrating parallel to the conductor line can be almost completely reflected, and light with an electric field vector component perpendicular to the conductor line can be almost completely transmitted. As a result, the wire grid type polarizing element can be used as a polarizing element that produces a single polarization, and the light that is not transmitted can be reflected and reused, which is desirable from the viewpoint of effective utilization of light. Note that the polarizing element referred to here includes a polarizing element that can be used as a polarizing beam splitter for separating incident light into S-polarized light and P-polarized light.

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

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

[0008] Furthermore, Patent Document 4 discloses a projection type video display device using a reflective liquid crystal display element and a reflective wire grid polarizer as a polarization beam splitter. In the projection type video display device using the reflective liquid crystal display element described in Patent Document 4, the reflective wire grid polarizer is disposed at an angle of about 45° obliquely with respect to the optical axis of the light emitted from the light source. The light emitted from the light source enters the reflective wire grid at an incident angle of about 45° obliquely, and is separated into a first polarization (reflected light) and a second polarization (transmitted light). Next, the first polarization reflected by the reflective wire grid polarizer is modulated and reflected by the reflective liquid crystal display element to become the second polarization, and the second polarization passes through the reflective wire grid polarizer and is projected and displayed.

[0009] In addition, Patent Document 5 discloses a vehicle headlamp using a reflective wire grid polarizer as a polarization beam splitter. Also in the vehicle headlamp described in Patent Document 5, the reflective wire grid polarizer is disposed at an angle of about 45° obliquely with respect to the optical axis of the light emitted from the light source. The light emitted from the light source enters the reflective wire grid at an incident angle of about 45° obliquely, and is separated into a first polarization (reflected light) and a second polarization (transmitted light).

[0010] When the reflective wire grid polarizer is disposed at an angle of about 45° obliquely with respect to the light emitted from the light source, such as in the projection type video display device described in Patent Document 4 and the vehicle headlamp described in Patent Document 5 above, the incident light not only enters the reflective wire grid polarizer at a single incident angle of 45°, but also enters at an incident angle in the range of about 45° ± 15°.

[0011] In addition, Patent Document 6 discloses a wire grid polarizing beam splitter in which a plurality of grids made entirely of silver or aluminum are formed to protrude on a substrate.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Summary of the Invention

Problems to be Solved by the Invention

[0013] By the way, the temperature environment generally required for equipment used in vehicles is -40 to 105°C. However, especially for equipment such as a head-up display mounted on a dashboard inside a vehicle in summer, when considering use in a high-temperature environment, high heat resistance and heat dissipation are required. In this regard, the wire grid polarizing plates described in Patent Documents 1 to 3 require further improvement in terms of heat resistance and heat dissipation. In addition, in order to brightly illuminate a night road with the vehicle headlamp described in Patent Document 5, it is essential to increase the brightness of the vehicle headlamp. Therefore, the wire grid polarizing plate described in Patent Document 5 is required to have high heat resistance and heat dissipation against heat from the light source.

[0014] Furthermore, in a conventional wire grid polarizing element, since the uneven shape on its surface is generally formed by photolithography technology or etching technology, there is also a problem that the manufacturing cost increases and it is not suitable for mass production.

[0015] As a result of intensive research to solve the above problems, the present inventor has found the following findings. First, the substrate of the wire grid polarizing element is formed of a transparent inorganic material, and the grid structure provided on the substrate is integrally formed of a transparent organic material. Thereby, the wire grid polarizing element can have a hybrid structure composed of an organic material and an inorganic material. As a result, the heat dissipation property of the wire grid polarizing element can be significantly improved.

[0016] Furthermore, as the grid structure, a grid structure in which a base portion provided along the surface of the substrate and a plurality of protruding ridges protruding from the base portion are integrally formed is used. Thereby, since the grid structure can be formed by a technique such as nanoimprint, the manufacturing cost of the grid structure can be reduced and mass production is also possible as compared with the case of using photolithography technology or etching technology.

[0017] Furthermore, when providing a functional film such as a reflective film that reflects light or an absorption film that absorbs light on the protruding ridges of the grid structure, the covering range and covering form of the protruding ridges by the functional film are preferably adjusted. That is, the tip and the upper side of one side or both sides of the side surface of the protruding ridge are covered so as to be wrapped by the functional film, while the lower side of the side surface of the protruding ridge and the surface of the base portion are left open without being covered by the functional film. And the functional film has a rounded shape that bulges in the width direction of the protruding ridge so as to cover and wrap the tip and the upper side of the side surface of the protruding ridge. Furthermore, the maximum width (W MAX ) of the grid formed by combining the protruding ridge and the functional film covering the protruding ridge is made to be equal to or greater than the width (W B ) of the bottom of the protruding ridge, and the shape and size of the protruding ridge and the functional film are adjusted. Furthermore, it is preferable to limit the range in which the functional film covers the side surface of the protruding ridge to a specific range on the upper side of the side surface (for example, a range of 25% or more and 80% or less of the height (H) of the protruding ridge).

[0018] Accordingly, even when obliquely incident light with a large and wide range of incident angles is incident on the wire grid polarizing element, it is possible to suppress a decrease in the transmittance (Tp) of the second polarization (P polarization) in the wire grid polarizing element depending on the incident angle. Therefore, the product (Tp×Rs) of the reflectance (Rs) of the reflection axis of the first polarization (S polarization) and the transmittance (Tp) of the transmission axis of the second polarization (P polarization) in the wire grid polarizing element can be maintained at a high value. Thus, when the wire grid polarizing element is used as, for example, a polarization beam splitter, sufficient transmittance and polarization separation characteristics can be obtained even for obliquely incident light with a large incident angle and a wide range.

[0019] By the way, in the imprint molding such as the above nanoimprint, the fine concavo-convex shape of the master is pressed against the uncured resin layer formed on the substrate, the uncured resin layer is cured in that state, and the master is peeled off, so that the fine concavo-convex shape can be formed on the substrate.

[0020] In imprint molding, if the thickness (layer thickness) of the uncured resin layer when the master is pressed is uneven, the peeling force applied when peeling the master from the cured resin layer (hereinafter referred to as the "cured resin layer") becomes uneven in the plane of the cured resin layer. Then, there is a risk that a part of the cured resin layer will peel off from the substrate. In addition, the cured resin layer peeled off from the substrate remains on the master, and the master cannot be reused repeatedly. Furthermore, when peeling the master, the fine concavo-convex shape transferred to the cured resin layer may be deformed, and the optical characteristics due to the fine concavo-convex structure may deteriorate.

[0021] Also, in imprint molding, when the master is pressed, if the followability of the uncured resin composition to the fine concavo-convex shape is low, a portion where the fine concavo-convex shape of the master is not transferred will occur in the uncured resin layer.

[0022] Therefore, in order to make the layer thickness of the uncured resin layer uniform when the master disk is pressed against it and to improve the followability of the uncured resin composition to the fine concavo-convex shape, for example, Patent Documents 7 and 8 have developed a technique 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 bifunctional monomer in the resin composition.

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

[0025] Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide a wire grid polarizing element having excellent heat resistance, a method for manufacturing the polarizing element, and a projection display device and a vehicle including the polarizing element.

Means for Solving the Problems

[0026] In order to solve the above problems, according to one aspect of the present invention, a substrate made of an inorganic material, a grid structure integrally formed of an organic material, having a base portion provided on the substrate and a plurality of protruding ridges protruding from the base portion, a functional film made of a metal material and covering a part of the protruding ridges, and the organic material is a cured product of an imprintable photocurable acrylic resin containing a photopolymerizable component, the photopolymerizable component includes resin (A), resin (B), and the resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, the resin (B) is a bifunctional compound, The content ratio of the resin (A) with respect to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less, There is provided a wire grid polarizing element in which the content ratio of the resin (B) with respect to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less.

[0027] The photopolymerizable component further contains a resin (C), The resin (C) is an acrylate monomer having three or more functional groups, The content ratio of the resin (C) with respect to the entire photopolymerizable component may be 1% by mass or more and 30% by 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, bisacrylic acid (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene, 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 bisacrylic acid (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene.

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

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

[0033] After the cured product of the imprint photosensitive acrylic resin is held at 150 °C for 500 hours, the YI value of the cured product may be 3.0 or less.

[0034] The storage elastic modulus of the cured product of the imprint photosensitive acrylic resin at 30 °C is 2.0×10 9 Pa or more, and the storage elastic modulus of the cured product at 120 °C may be 1.3×10 8 Pa or more.

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

[0036] After the cured product of the imprint photosensitive acrylic resin is held at 150 °C for 500 hours, the average transmittance of the cured product for light in the wavelength range of 430 nm or more and 680 nm or less is 91% or more, and the average transmittance of the cured product for light in the wavelength range of 430 nm or more and 510 nm or less may be 90% or more.

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

[0038] At least the portion of the rib portion covered by 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 rib portion is bent in the middle in the height direction of the rib portion, The upper part of the 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 rib 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 5° or more and 10° or less.

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

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

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

[0045] The coverage rate (Rc) of the second side surface on the side opposite to the inclined side of the rib portion among both side surfaces of the rib portion may be 35% or more and 55% or less.

[0046] The coverage rate (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] It may be a hybrid wire grid polarizing element in which the substrate made of the inorganic material and the grid structure made of the organic material are combined.

[0052] The surface of the functional film covering and wrapping the ridge portion has a roundness and bulges in the width direction of the ridge portion. The maximum width (W MAX ) of the functional film covering and wrapping the ridge portion is such that the width (W B ) of the ridge portion of the portion not covered by the functional film at a position 20% above the height of the ridge portion from the bottom of the ridge portion is equal to or greater than that.

[0053] The cross-sectional shape of the entire convex structure composed of the ridge portion and the functional film may have a constricted portion where the width in the width direction of the entire convex structure becomes narrow immediately below the lower end portion of the functional film covering and wrapping the ridge portion.

[0054] The product (Tp × Rs) of the transmission axis transmittance (Tp) and the reflection axis reflectance (Rs) of incident light with an incident angle of 45° with respect to the wire grid polarizing element 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 ridge portion may be 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 ridge portion in a cross-section orthogonal to the reflection axis direction of the wire grid polarizing element may be a trapezoid, a triangle, a bell shape, or an ellipse whose width becomes narrower as it moves away from the base portion.

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

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

[0062] The functional film may further have 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 with an incident angle of +θ and the transmission axis transmittance (Tp(-)) of incident light with an incident angle of -θ with respect to the wire grid polarizing element may be within 3%.

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

[0065] The wire grid polarizing element may be a polarization beam splitter that separates obliquely incident light into a first polarization and a second polarization.

[0066] In order to solve the above problems, according to another aspect of the present invention, The manufacturing method of the above-described wire grid polarizing element, A step of forming a grid structure material made of an organic material on a substrate made of an inorganic material; A step of forming a grid structure in which a base portion provided on the substrate and a plurality of ridge portions protruding from the base portion are integrally formed by performing nanoimprint on the grid structure material; A step of forming a functional film that covers a part of the ridge portion using a metal material; including The organic material is a cured product of a photocurable acrylic resin for imprinting containing a photopolymerizable component, The photopolymerizable component comprises resin (A), resin (B), and 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, the content of resin (A) relative to the whole photopolymerizable component is 20% by mass or more and 42% by mass or less, A method for manufacturing a wire grid polarizing element is provided, wherein the content of resin (B) relative to the whole photopolymerizable component is 43% by mass or more and 66% by mass or less.

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

[0068] The photopolymerizable component further contains resin (C), resin (C) is an acrylate monomer having three or more functional groups, the content of resin (C) relative to the whole photopolymerizable component is 1% by mass or more and 30% by mass or less, The step of forming the grid structure may include generating a first mixed resin by mixing resin (A) and resin (B), and generating a second mixed resin by mixing resin (C) into the first mixed resin. and

[0069] In the step of forming the functional film, film formation may be alternately performed from a plurality of directions with respect to the convex ridges by sputtering or vapor deposition.

[0070] To solve the above problems, according to another aspect of the present invention, a light source, a polarization beam splitter arranged such 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 polarization and a second polarization; a reflective liquid crystal display element arranged such that the first polarization reflected by the polarization beam splitter or the second polarization transmitted through the polarization beam splitter is incident, and reflecting and modulating the incident first polarization or second polarization; a lens arranged such that the first polarization or the second polarization reflected and modulated by the reflective liquid crystal display element is incident through the polarization beam splitter; comprising a projection display device is provided, wherein the polarization beam splitter is composed of the wire grid polarizing element.

[0071] The predetermined range of the incident angle may be 30° or more and 60° or less.

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

[0073] To solve the above problems, according to another aspect of the present invention, a vehicle provided with the projection display device is provided.

Advantages of the Invention

[0074] According to the present invention, a wire grid polarizing element excellent in heat resistance can be provided.

Brief Description of the Drawings

[0075]

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Embodiments for Carrying Out the Invention

[0076] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations are omitted. For convenience of explanation, the states of the respective members disclosed in the following drawings are schematically represented with scales and shapes different from the actual ones in some cases.

[0077] <1. Outline of Wire Grid Polarizing Element> First, with reference to FIGS. 1 and 2 and the like, the outline of the wire grid polarizing element 1 according to the first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view schematically showing the wire grid polarizing element 1 according to the present embodiment. FIG. 2 is a plan view schematically showing the wire grid polarizing element 1 according to the present embodiment.

[0078] The wire grid polarizing element 1 according to this embodiment is a reflective polarizing element and a wire grid type polarizing element. The wire grid polarizing element 1 may be, for example, a plate-shaped wire grid polarizing plate. The wire grid polarizing plate is a wire grid type polarizing plate having a plate shape. The wire grid polarizing plate may be, for example, flat plate-shaped or curved plate-shaped. That is, the surface of the wire grid polarizing element 1 (the surface on which light is incident) may be flat or curved. Hereinafter, an example in which the wire grid polarizing element 1 according to this embodiment is a flat plate-shaped wire grid polarizing plate will be described, but the wire grid polarizing element of the present invention is not limited to such an example and can have an arbitrary shape according to its use, function, etc.

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

[0080] As shown in FIGS. 1 and 2, the wire grid polarizing element 1 (hereinafter, may also be abbreviated as "polarizing element 1") includes a transparent substrate 10, a transparent grid structure 20, and an opaque functional film (for example, a reflective film 30).

[0081] In this specification, "transparent" means that the transmittance of light with a wavelength λ belonging to the use band (for example, the visible light band, the infrared light band, or the visible light and infrared light bands, etc.) is high. For example, it means that 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 rays) is larger than the wavelength band of visible light and is, 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 use band in the polarizing element 1 according to the present embodiment is preferably, for example, 400 nm or more and 800 nm or less, and more preferably 420 nm or more and 680 nm or less. Since the polarizing element 1 according to the present embodiment is formed of a material that is transparent to the light in the use band, it does not adversely affect the polarization characteristics of the polarizing element 1, the light transmittance, etc.

[0082] The substrate 10 is made of a transparent inorganic material such as glass. 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 having excellent heat resistance. The grid structure 20 has an uneven 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 protruding strip portions 22 protruding from the base portion 21 in a grid pattern. The base portion 21 and the plurality of protruding strip 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 the same over the entire main surface of the substrate 10, but it does not have to be exactly the same thickness, and may vary with a certain degree of error from the reference thickness of TB. For example, TB may vary by about ±3 μm from the reference thickness of 6 μm. In this way, the thickness TB of the base portion 21 is determined by allowing for molding errors when molding the base portion 21 by imprinting or the like.

[0085] The multiple convex streaks 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 multiple convex streaks 22 arranged in the X direction of the polarizing element 1. The multiple convex streaks 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 adjacent convex streaks 22 in the X direction. This gap serves as a path for incident light to enter. Each convex streaks 22 is a wall-like protrusion formed to protrude and extend 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 multiple convex streaks 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 part of the convex stripe portion 22 of the grid structure 20. The functional film may be, for example, a reflective film 30 having a function of reflecting incident light incident on the polarizing element 1, or an absorbing film (not shown) having a function of absorbing the incident light, or a film having other functions. In this embodiment, an example in which the functional film is the reflective film 30 will be described, but the functional film of the present invention is not limited to the example of the reflective film 30.

[0087] The reflective film 30 is a thin film made of a metal material such as aluminum or silver (such as a metal or a metal oxide). The reflective film 30 is formed so as to cover at least the top of the rib portion 22. The reflective film 30 may be composed of a metal film that functions as the metal fine wires of the wire grid. The reflective film 30 has a function of reflecting the incident light that enters the grid structure 20.

[0088] The rib portion 22 of the grid structure 20 and the reflective film 30 constitute the grid of the wire grid polarizing element 1. The pitch P in the X direction of the plurality of rib portions 22 in the grid structure 20 (that is, the arrangement pitch of the grid) is set to a pitch (for example, 1 / 2 or less) that is smaller than the wavelength λ of the incident light (for example, visible light). Thereby, the polarizing element 1 almost reflects the light (S polarized light) of the electric field vector component that vibrates in the direction parallel to the reflective film 30 (conductor line) extending in the Y direction (reflection axis direction: Y direction), and is perpendicular to the reflective film 30 (conductor line). The light (P polarized light) of the electric field vector component vibrating in the direction (transmission axis direction: X direction) can be almost transmitted.

[0089] As described above, the wire grid polarizing element 1 according to the present embodiment realizes a polarizing function by a combination of a grid structure 20 having a fine concavo-convex structure and a functional film (for example, a reflective film 30) selectively added to the rib portion 22 of the grid structure 20. The substrate 10 of the wire grid polarizing element 1 is made of an inorganic material such as glass that is extremely excellent in heat resistance, and the grid structure 20 is made of an organic resin material having heat resistance. Thus, the wire grid polarizing element 1 according to the present embodiment is a hybrid type polarizing element that combines an organic material and an inorganic material. Therefore, heat can be efficiently dissipated from the grid structure 20 with a small thermal resistance R [m 2 ·K / W] to the substrate 10, so that the heat dissipation is excellent. Therefore, the hybrid type wire grid polarizing element 1 according to the present embodiment is superior in heat resistance and heat dissipation compared to a conventional film type polarizing element made of only an organic material (heat resistance: about 100 ° C), and has heat resistance in a high temperature environment up to about 200 ° C, for example. Therefore, while realizing excellent polarization characteristics, a good heat dissipation effect can be maintained.

[0090] Furthermore, the wire grid polarizing element 1 according to the present 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, a dielectric material such as SiO2. This protective film 40 may be laminated on the entire surface of the wire grid polarizing element 1 so as to cover all the surfaces of the base portion 21, the ridge portion 22, and the reflective film 30 of the grid structure 20 (see FIG. 7). By providing such a protective film 40, an advantageous effect that the thermal resistance R of the polarizing element 1 can be further reduced can be obtained, so that excellent polarization characteristics can be realized while maintaining a better heat dissipation effect.

[0091] Also, as described above, the grid structure 20 in which the base portion 21 and the ridge portion 22 are integrally formed can be manufactured using a printing technique such as nanoimprinting, so that a fine concavo-convex structure can be realized with a simple manufacturing process. Therefore, compared with the case of manufacturing using photolithography technology or etching technology, the cost and labor required for manufacturing the grid structure 20 can be reduced. Thus, the hybrid type polarizing element 1 according to the present embodiment has an advantage that the manufacturing cost can be significantly reduced compared with a polarizing element made only of a conventional inorganic material, and the unit price of the wire grid polarizing element 1 can be made inexpensive.

[0092] On the other hand, a conventional film-type organic polarizing plate uses a large amount of organic materials, and the thicknesses of the substrate (base film), the double-sided tape (OCA: Optically Clear Adhesive), and the grid structure are large. Therefore, compared with the hybrid type polarizing element 1 according to the present embodiment, it is considered that the heat dissipation and heat resistance are inferior.

[0093] In addition, the wire grid polarizing element 1 according to the present embodiment has a grid composed of the convex ridges 22 of the grid structure 20 and the reflective film 30, which has a special tree shape as shown in FIG. 1 etc. (details will be described later). Thereby, even when light is incident obliquely on the polarizing element 1 at a large incident angle θ in a wide range (for example, 30 to 60°), the transmittance of the second polarized light (P polarized light) transmitted through the polarizing element 1 (that is, the transmission axis transmittance Tp) can be suppressed from decreasing depending on the incident angle θ of the obliquely incident light. Therefore, the product (Tp×Rs) of the reflectance of the first polarized light (S polarized light) reflected by the wire grid polarizing element 1 (that is, the reflection axis reflectance Rs) and the transmission axis transmittance Tp can be maintained at a high value of, for example, 70% or more. Therefore, the polarizing element 1 according to the present embodiment is excellent in the polarization separation characteristics represented by the Tp×Rs, and can preferably separate obliquely incident light into S polarized light (reflected light) and P polarized light (transmitted light). Thus, the polarizing element 1 according to the present embodiment can obtain sufficient transmittance and polarization separation characteristics even for obliquely incident light with a large incident angle θ in a wide range.

[0094] As described above, the wire grid polarizing element 1 according to the present embodiment is excellent in heat resistance and heat dissipation, can reduce the manufacturing cost, and is also excellent in transmittance and polarization separation characteristics for obliquely incident light with a large incident angle θ in a wide range. Therefore, the wire grid polarizing element 1 according to the present embodiment can be preferably applied as various components of various products. For example, the polarizing element 1 can be applied to a polarizing beam splitter installed in a smart display. In addition, the polarizing element 1 can be applied to a polarizing element for countermeasures against heat from sunlight, a polarizing element for countermeasures against heat from an LED light source, a polarizing reflection mirror, etc. installed in a head-up display (HUD). Furthermore, the polarizing element 1 can also be applied to a polarizing beam splitter installed in a headlight such as an adaptive driving beam (ADB). In addition, the polarizing element 1 can also be applied to a lens-integrated retardation element, a lens-integrated polarizing element, etc. installed in various devices for augmented reality (AR) or virtual reality (VR).

[0095] <2. Components of the wire grid polarizing element> Next, with reference to FIGS. 1 and 2 and the like, the components of the wire grid polarizing element 1 according to the present embodiment will be described in detail.

[0096] <2.1. Substrate> As shown in FIG. 1, the wire grid polarizing element 1 according to the present embodiment includes a transparent substrate 10. The substrate 10 is made of an inorganic material that is transparent and has a certain degree of strength.

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

[0098] Further, the shape of the substrate 10 is not particularly limited and can be appropriately selected according to the performance required for the polarizing element 1 and the like. For example, it can be configured to have a plate shape or a curved surface. Also, from the viewpoint of not affecting the polarization characteristics of the polarizing element 1, the surface of the substrate 10 can be a flat surface. Furthermore, the thickness TS of the substrate 10 is not particularly limited either, and can be, for example, in the range of 0.02 to 10.0 mm.

[0099] <2.2. Grid structure> As shown in FIGS. 1 and 2, the polarizing element 1 according to the present embodiment includes a grid structure 20 having the base portion 21 and the lattice-shaped ridges 22 on the substrate 10. The grid structure 20 can obtain desired polarization characteristics by providing a reflection film 30, which will be described later, on the ridges 22.

[0100] When light is incident from the surface side where the grid structure 20 is formed with respect to the polarizing element 1, a part of the incident light is reflected by the reflective film 30. Among the light incident on the reflective film 30, light having an electric field component in a direction orthogonal to the longitudinal direction of the convex strip portion 22 (i.e., the extending direction of the convex strip portion 22 = the reflection axis direction: Y direction), that is, in the width direction of the convex strip portion 22 = the transmission axis direction: X direction, passes through the polarizing element 1 with a high transmittance. On the other hand, most of the light having an electric field component in a direction parallel to the longitudinal direction of the convex strip portion 22 (i.e., the extending direction of the convex strip portion 22 = the reflection axis direction: Y direction) among the light incident on the reflective film 30 is reflected by the reflective film 30. Therefore, in the present embodiment, by providing the grid structure 20 partially covered by the reflective film 30, linearly polarized light can be produced. Note that the same polarization effect can be obtained for light incident from the back surface side of the substrate 10 as well.

[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 is a portion for supporting the convex strip portion 22. When the concavo-convex structure (convex strip portion 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 convex strip portion 22 are integrally formed of the same material. Further, since the grid structure 20 has the base portion 21, the strength of the convex strip portion 22 can be increased as compared with the case where the convex strip portion 22 is directly formed on the substrate 10. For this reason, the durability of the grid structure 20 can be enhanced. 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 enhanced.

[0102] Note that the thickness TB of the base portion 21 is not particularly limited, but from the viewpoint of more reliably supporting the convex strip portion 22 and from the viewpoint of easily performing imprint molding, it is preferably 1 nm or more, and more preferably 10 nm or more. Also, 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] Further, according to the polarization element 1 according to the present embodiment, since the base portion 21 and the plurality of ridge portions 22 of the grid structure 20 are directly formed on the substrate 10, the thickness TB of the base portion 21 can be reduced. Here, in order to improve the heat dissipation property from the grid structure 20 to the substrate 10, it is preferable to reduce the temperature difference ΔT [° C] between the front surface and the back surface of the base portion 21 by reducing the thickness TB of the base portion 21. The temperature difference ΔT is the temperature difference between the temperature T1 [° C] of the outermost surface (the root portion of the plurality of ridge portions 22) of the base portion 21 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. Thereby, the heat of the grid structure 20 made of an organic material can be quickly transmitted to the substrate 10 made of an inorganic material and efficiently released from the substrate 10 to the outside of the polarization element 1, so that the temperature difference ΔT can be, for example, 32 ° C or less. Further, the thickness TB of the base portion 21 is more preferably 0.09 mm or less, whereby the temperature difference ΔT can be, for example, 20 ° C or less. Further, the thickness TB of the base portion 21 is more preferably 0.045 mm or less, whereby the temperature difference ΔT can be, for example, 10 ° C or less. Further, the thickness TB of the base portion 21 is particularly preferably 0.02 mm or less, whereby the temperature difference ΔT can be, for example, 5 ° C or less. Thus, by reducing the thickness TB of the base portion 21, the heat dissipation property from the grid structure 20 to the outside through the substrate 10 can be improved, so that the heat dissipation property and heat resistance of the polarization element 1 can be improved.

[0105] Furthermore, as shown in FIGS. 1 and 2, the grid structure 20 has a plurality of ridge portions 22 protruding from the base portion 21. The ridge portion 22 extends in the longitudinal direction with the reflection axis direction (Y direction) of the polarization element 1 according to the present embodiment as the longitudinal direction. The plurality of ridge portions 22 are arranged at a predetermined pitch in the X direction and are arranged at a predetermined interval from each other, thereby forming a lattice-like uneven structure.

[0106] Here, as shown in FIG. 1, in the longitudinal cross-section (XZ cross-section) orthogonal to the reflection axis direction (Y direction) of the polarizing element 1, it is necessary that the pitch P in the transmission axis direction (X direction) of the convex stripe portion 22 is shorter than the wavelength of the light in the use band. The reason for this is to obtain the polarizing action described above. More specifically, from the viewpoint of achieving both easy manufacturability of the convex stripe portion 22 and polarization characteristics, the pitch P of the convex stripe portion 22 is preferably 50 to 300 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm.

[0107] Also, as shown in FIGS. 1 and 2, the width W of the bottom of the convex stripe portion 22 in the above longitudinal cross-section (XZ cross-section) B is not particularly limited, but from the viewpoint of achieving both easy manufacturability and polarization characteristics, it is preferably about 10 to 150 nm, and more preferably about 10 to 100 nm. Further, the width W of the top of the convex stripe portion 22 T is not particularly limited, but from the viewpoint of achieving both easy manufacturability and polarization characteristics, it is preferably about 5 to 60 nm, and more preferably about 10 to 30 nm.

[0108] Note that the width W of the bottom of the convex stripe portion 22 B and the width W of the top T can be measured by observing with a scanning electron microscope or a transmission electron microscope. For example, by observing a cross-section (XZ cross-section) orthogonal to the absorption axis direction or the reflection axis direction of the polarizing element 1 using a scanning electron microscope or a transmission electron microscope, for any four convex stripe portions 22, the width of the convex stripe portion 22 at a height position 20% above the height H of the convex stripe portion 22 from the bottom of the convex stripe portion 22 is measured, and the arithmetic mean value thereof is taken as the width W of the bottom of the convex stripe portion 22 B can be obtained. Also, for the above-mentioned arbitrary four convex stripe portions 22, the width of the convex stripe portion 22 at a height position 20% below the height H of the convex stripe portion 22 from the tip 22a of the convex stripe portion 22 is measured, and the arithmetic mean value thereof is taken as the width W of the top of the convex stripe portion 22 T can be obtained.

[0109] Also, as shown in FIG. 1, the height H of the ridge portion 22 in the longitudinal section (XZ section) is not particularly limited, but from the viewpoint of achieving both ease of manufacture and polarization characteristics, it is preferably about 50 to 350 nm, and more preferably about 100 to 300 nm. The height H of the ridge portion 22 can be measured by observing it with a scanning electron microscope or a transmission electron microscope. For example, a cross-section orthogonal to the absorption axis direction or the reflection axis direction of the polarization element 1 is observed using a scanning electron microscope or a transmission electron microscope, and for the ridge portion 22 at any four locations, the height of the ridge portion 22 at the center position in the width direction of the ridge portion 22 is measured, and the arithmetic mean value thereof can be taken as the height H of the ridge portion 22.

[0110] The shape of the ridge portion 22 of the grid structure 20 is preferably a tapered shape in order to obtain good polarization separation characteristics for obliquely incident light. Here, the tapered shape means a shape in which the width W (the width in the X direction in the XZ section) of the ridge portion 22 gradually narrows as it moves away from the base portion 21. In other words, it is a shape in which the width W of the ridge portion 22 gradually narrows from the bottom to the top of the ridge portion 22. Therefore, when the ridge portion 22 has a tapered shape, the width W at the top of the ridge portion 22 T is smaller than the width W at the bottom of the ridge portion 22 B (W T <W B ).

[0111] FIG. 3 shows a specific example of the tapered shape of the rib portion 22 according to the present embodiment. As shown in FIG. 3, the cross-sectional shape of the rib 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 as long as it is the above-mentioned tapered shape, in which the width W becomes narrower as it moves away from the base portion 21. For example, the cross-sectional shape of the rib portion 22A shown in FIG. 3 is a trapezoid (tapered shape), the cross-sectional shape of the rib portion 22B is a triangle, the cross-sectional shape of the rib portion 22C is a bell shape, and the cross-sectional shape of the rib portion 22D is a wedge shape with rounded top and bottom. Thus, since the rib portion 22 has a tapered shape, it is easy to form the reflective film 30 that covers the tip 22a and a part of the side surface 22b of the rib portion 22, and the polarization characteristics can be imparted to the polarization element 1. Also, since the tapered shape can be formed by nanoimprinting, it is advantageous in terms of ease of manufacturing.

[0112] Further, since the rib portion 22 has 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 antireflection effect of incident light due to a physical change in the refractive index of the grid structure 20 can be obtained. Thus, it is expected that the reflectance on the surface of the rib portion 22 of the grid structure 20 can be reduced and the transmittance of the grid structure 20 can be improved.

[0113] FIG. 4 shows a specific example of the shape of the recess 24 formed between the mutually adjacent rib portions 22, 22. The recess 24 is a groove extending in the longitudinal direction (Y direction) of the rib 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 becomes narrower 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. As the shape of these recesses 24, an optimum shape can be appropriately selected in consideration of productivity such as mold release property during nanoimprint formation.

[0114] In addition, the material constituting the grid structure 20 is not particularly limited as long as it is a transparent organic material, and known organic materials can be used. For example, from the viewpoint of ensuring transparency and excellent manufacturability, it is preferable to use various thermosetting resins, various ultraviolet curable resins, etc. as the material of the grid structure 20.

[0115] Furthermore, from the viewpoints of manufacturability and manufacturing cost, it is preferable to use a material different from that of the substrate 10 for the material constituting the grid structure 20. In addition, when the materials of the grid structure 20 and the substrate 10 are different, their refractive indices will be different. Therefore, when there is an influence on the refractive index of the entire polarization element 1, 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 the material constituting the grid structure 20. The epoxy polymerizable compound is a monomer, oligomer, or prepolymer having one or more epoxy groups in the molecule. Examples of the epoxy polymerizable compound include various bisphenol type epoxy resins (bisphenol A type, F type, etc.), novolak type epoxy resins, various modified epoxy resins such as rubber and urethane, naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolak type epoxy resins, stilbene type epoxy resins, triphenol methane type epoxy resins, dicyclopentadiene type epoxy resins, triphenyl methane 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 the "monofunctional monomer" include carboxylic acids (such as acrylic acid), hydroxy compounds (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), 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, 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, etc.

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

[0120] Examples of compounds other than the acrylic polymerizable compounds 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, polyester oligomer, and the like.

[0121] In addition, examples of the curing initiator for the curable resin described above include a thermal curing initiator, a photo-curing initiator, and the like. The curing initiator may be cured by some energy ray (for example, an electron beam) other than heat and light. When the curing initiator is a thermal 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-curing resin.

[0122] Among these, it is preferable to use an ultraviolet curing initiator as the curing initiator. The ultraviolet curing initiator is a kind of photo-curing initiator. Examples of the ultraviolet curing initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and the like. Therefore, the curable resin is preferably an ultraviolet curable resin. Further, from the viewpoint of transparency, the curable resin is more preferably an ultraviolet curable acrylic resin.

[0123] The method for forming the grid structure 20 is not particularly limited as long as it can form the base portion 21 and the rib portion 22 described above. For example, a method for forming unevenness such as photolithography or imprinting can be used. Among these, from the viewpoint of being able to form an uneven pattern in a short time and easily, and further being able to surely form the base portion 21, it is preferable to form the base portion 21 and the rib portion 22 of the grid structure 20 by imprinting.

[0124] When forming the base portion 21 and the ridge portion 22 of the grid structure 20 by nanoimprinting, for example, after applying a material (grid structure material) for forming the grid structure 20 on the substrate 10, a master disk with unevenness is pressed against the grid structure material, and in this state, ultraviolet light is irradiated or heat is applied to cure the grid structure material. Thereby, the grid structure 20 having the base portion 21 and the ridge portion 22 can be formed.

[0125] <2.3. Reflective film (functional film)> As shown in FIGS. 1 and 2, the polarization element 1 according to the present embodiment includes a reflective film 30 formed on the ridge portion 22 of the grid structure 20.

[0126] As shown in FIG. 1, the reflective film 30 is formed so as to cover and wrap the tip 22a and a part of the side surface 22b of the ridge portion 22 of the grid structure 20. And as shown in FIG. 1, the reflective film 30 is formed so as to extend along the longitudinal direction (Y direction) of the ridge portion 22 of the grid structure 20. Thereby, the reflective film 30 can reflect the light having an electric field component in the direction parallel to the longitudinal direction of the ridge portion 22 (reflection axis direction: Y direction) among the light incident on the polarization element 1.

[0127] The material constituting the reflective film 30 is not particularly limited as long as it is a material having reflectivity with respect to light in the used band. For example, single metal elements such as Al, Ag, Cu, Mo, Cr, Ti, Ni, W, Fe, Si, Ge, Te, and metal materials such as alloys containing one or more of these elements can be mentioned.

[0128] Note that the reflective film 30 may be a single-layer film made of the above metal, or may be a multi-layer film made of a plurality of metal films. Further, if the reflective film 30 has a reflective function, it can also include other layers such as a dielectric film as necessary. The dielectric film is a thin film made of a dielectric. As the material of the dielectric film, general materials such as SiO2, Al2O3, MgF2, and TiO2 can be used. Further, the refractive index of the dielectric film is preferably greater than 1.0 and not more than 2.5. Note that 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 Ridge Portions and the Reflective Film> Here, the special shapes of the ridge portions 22 of the grid structure 20 and the reflective film 30 in the polarization element 1 according to the present embodiment will be described in detail.

[0130] In the polarization element 1 according to the present embodiment, as shown in FIGS. 1 and 5, the reflective film 30 covers the tip 22a and at least the upper side of one side surface 22b of the ridge portion 22 of the grid structure 20, and is formed so as not to cover the lower sides of both side surfaces 22b of the ridge portion 22 and the base portion 21. In the examples of FIGS. 1 and 5, the reflective film 30 covers the upper sides of both side surfaces 22b of the ridge portion 22, but may cover only the upper side of one side surface 22b of the ridge portion 22.

[0131] Here, the state where the "reflective film 30 covers the tip 22a and at least the upper side of one side surface 22b of the ridge portion 22 of the grid structure 20" means that, for example, as shown in FIGS. 1 and 5, both the "tip 22a of the ridge portion 22" and the "upper side of the side surface 22b connecting the tip 22a of the ridge portion 22 and the base portion 21" are continuously covered by the reflective film 30, while the "lower side of the side surface 22b" and the "base portion 21" are exposed without being covered by the reflective film 30. In this state, the reflective film 30 does not cover all of the side surfaces 22b of the ridge portion 22 (all the side surfaces 22b from the tip 22a of the ridge portion 22 to the base portion 21).

[0132] Furthermore, the surface of the reflective film 30 that covers and wraps the tip 22a of the rib portion 22 and the upper side of at least one side surface 22b (hereinafter, may also be referred to as the "top of the rib portion 22") has a rounded and curved shape (for example, a vertically long substantially elliptical shape) and bulges in the width direction (X direction) of the rib portion 22. In this way, the surface of the reflective film 30 has a rounded and smooth curved surface shape and does not have sharp corner portions or stepped portions. The maximum width W of the reflective film 30 that covers and wraps the top of the rib portion 22 MAX is the width W at the bottom of the rib portion 22 B as described above. Furthermore, W MAX is preferably larger than W B .

[0133] Here, the maximum width W of the reflective film 30 that covers and wraps the rib portion 22 MAX is the maximum horizontal width among the horizontal widths of the outermost surfaces on both sides of the reflective film 30 in the width direction (X direction) of the rib portion 22. As shown in FIGS. 1 and 5, etc., the horizontal widths (widths in the X direction) of the outermost surfaces on both sides of the reflective film 30 that covers and wraps the rib portion 22 vary depending on the height position (height in the Z direction) of the reflective film 30, but the maximum value among 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 twice the thickness Ds on both sides of the reflective film 30 and the horizontal width W of the rib portion 22. For example, when light is incident on the grid structure 20 from the front direction (Z direction) (when the incident angle θ = 0°), W MAX corresponds to the effective grid width of the reflective film 30

[0134] The width W at the bottom of the rib portion 22 B is, as shown in FIGS. 1 and 3, the horizontal width (width in the X direction) of the rib portion 22 at a height position (height in the Z direction) 20% above the height H of the rib portion 22 from the lowermost part (upper surface of the base portion 21) of the rib portion 22. That is, the width W at the bottom of the rib portion 22 B is the horizontal width of the rib portion 22 at a position 0.2×H above the upper surface of the base portion 21

[0135] Also, the width W at the top of the rib portion 22 TAs shown in FIGS. 1 and 3, it is the horizontal width (width in the X direction) of the convex rib portion 22 at the height position (height in the Z direction) 20% below the height H of the convex rib portion 22 from the tip 22a of the convex rib portion 22. That is, the width W at the top of the convex rib portion 22 T is the horizontal width of the convex rib portion 22 at the position of the height 0.8×H upward from the upper surface of the base portion 21 (that is, the position of the height 0.2×H downward from the tip 22a of the convex rib portion 22).

[0136] In the following description, the convex structure formed by combining the convex rib portion 22 and the reflective film 30 may be referred to as a "grid", and the height of the convex structure (that is, the grid) formed by combining the convex rib portion 22 and the reflective film 30 may be referred to as the "grid height". Also, the maximum width W of the reflective film 30 covering the convex rib portion 22 MAX is referred to as the "grid maximum width W MAX ", and the width W at the bottom of the convex rib portion 22 B may be referred to as the "grid bottom width W B ". Also, the width W at the top of the convex rib portion 22 T may be referred to as the "width at the top of the convex rib portion W T ", and the width at the central position in the height direction of the convex rib portion 22 may be referred to as the "central width of the convex rib portion".

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

[0138] As described above, in the grid structure 20 according to the present embodiment, a tapered convex rib portion 22 and a reflective film 30 that covers only the tip 22a and the upper side of the side surface 22b of the convex rib portion 22 are formed. And the lower side of the side surface 22b of the convex rib portion 22 is not covered with the reflective film 30 and is open.

[0139] As a result, the cross-sectional shape of the convex strip portion 22 covered with the curved reflective film 30 (that is, the cross-sectional shape of the grid) has the following special cross-sectional shape. That is, as shown in FIGS. 1 and 5, etc., the horizontal width of the upper side portion of the convex strip portion 22 where the reflective film 30 exists (for example, the maximum grid width W MAX ) is large, and the horizontal width of the portion from the central portion to the bottom side of the convex strip portion 22 that is not covered with the reflective film 30 and is exposed (for example, the width W B ) of the bottom of the exposed convex strip portion 22 is small. And the cross-sectional shape of the entire convex structure (that is, the "grid") composed of the convex strip portion 22 and the reflective film 30 has a constriction portion that constricts inward and has a narrow width in the X direction at a position directly below the lower end portion of the curved reflective film 30. Such a special cross-sectional shape of the grid can be likened to the shape of a tree. Specifically, the portion of the leaf of the tree that is round and spreads out widely corresponds to the portion of the reflective film 30 that covers and wraps the top of the convex strip portion 22, the portion of the trunk of the tree corresponds to the lower side portion of the convex strip portion 22 that is not covered with the reflective film 30, and the portion of the ground where 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 strip portion 22 and the reflective film 30 of the grid structure 20 as described above is referred to as the "special tree shape".

[0140] The grid of the grid structure 20 of the polarizing element 1 according to the present embodiment has the above-described special tree shape. Thereby, for example, when incident light is incident on the polarizing element 1 from an oblique direction, the effective grid width W A becomes small, and the gap width W G becomes large. Here, the effective grid width W A is the width of the reflective film 30 in the direction perpendicular to the obliquely incident light. The gap width W G is the gap between two adjacent reflective films 30, 30 of the grid, and is the width of the gap in the direction perpendicular to the obliquely incident light. The effective grid width W AThe larger it is, the more likely the obliquely incident light is to be reflected by the reflection film 30 and the less likely it is to reach the transparent convex strip portion 22 and the base portion 21. Therefore, the transmittance of the obliquely incident light in the polarizing element 1 decreases. On the other hand, the larger the gap width W G is, the more likely the obliquely incident light is to pass through between two adjacent reflection films 30, 30 and reach the transparent convex strip portion 22 and the base portion 21. Thus, the transmittance for the obliquely incident light can be increased.

[0141] Therefore, since the grid of the polarizing element 1 according to the present embodiment has the above special tree shape, the gap width W for the obliquely incident light G becomes large, and the obliquely incident light passes through the gaps between the round reflection films 30, 30 and reaches the transparent grid structure 20 and is likely to transmit. Therefore, since the transmission axis transmittance Tp of the obliquely incident light is high, the transmittance for the obliquely incident light and the polarization separation characteristics (Tp×Rs characteristics) are very excellent. Furthermore, the reflection function of the obliquely incident light by the reflection film 30 and the transmission function of the obliquely incident light by the grid structure 20 can be realized in a well-balanced manner, and the polarization separation characteristics for the obliquely incident light can be further improved.

[0142] <2.5. Method for Forming Reflection Film and Specific Example> Here, with reference to FIG. 5, a method for forming the reflection film 30 will be described.

[0143] As a method for forming the reflection film 30 so that the reflection film 30 covers the tip 22a and a part of both side surfaces 22b of the convex strip portion 22 of the grid structure 20, as shown in FIG. 5, it is preferable to form the reflection film 30 by alternately performing sputtering or vapor deposition in an oblique direction (film formation incident angle φ) with respect to the convex strip portion 22 of the grid structure 20. Thereby, the reflection film 30 can be formed so as to cover and wrap the tip 22a and the upper side of both side surfaces 22b of the convex strip portion 22. The film formation incident angle φ for forming the reflection 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] Thus, 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. Thereby, the film formation conditions, material, and film thickness of the reflective film 30 can be easily changed. Also, even when the reflective film 30 is composed of a multilayer film, it can be easily dealt with. For this reason, film design utilizing the interference effect becomes possible by combining metals, semiconductors, and dielectrics, and when forming the reflective film 30 by etching as in the prior art, it is not necessary to consider the material configuration that can be etched. Thereby, it also becomes easy to adjust the reflectance of the polarized light wave parallel to the grid structure 20 and to adjust the transmittance (transmission amount) of the polarized light in the direction perpendicular to the grid. In addition, after forming the grid structure 20, by forming the reflective film 30, equipment such as a vacuum dry etching apparatus is not required, and it is not necessary to prepare complicated processes and safety devices such as gases and decontamination devices adapted to the etching material. Therefore, running costs such as equipment investment and maintenance can be reduced, and a cost advantage can also be obtained.

[0145] Note that the thickness Dt of the reflective film 30 covering the tip 22a of the ridge portion 22 shown in FIG. 5 and the thickness Ds of the reflective film 30 covering the side surface 22b of the ridge portion 22 are not particularly limited and can be appropriately changed according to the shape of the ridge portion 22 of the grid structure 20 and the performance required for the reflective film 30. For example, from the viewpoint of obtaining more excellent reflection 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. Note that the thickness Ds of the reflective film 30 is the thickness of the thickest portion among the reflective films 30 covering the side surface 22b of the ridge portion 22 as shown in FIG. 5.

[0146] Also, the shape of the reflective film 30 is not particularly limited as long as it can form the above-described special tree shape, and can be appropriately selected according to the conditions of the apparatus for forming the reflective film 30 and the performance required for 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 wrap around the top of the ridge portion 22 (the tip 22a and the upper side of the side surface 22b).

[0148] For example, the reflective film 30A shown in FIG. 6 covers the tops of the ridge portions 22A, 22B, and 22C having various cross-sectional shapes so as to wrap them roundly, and has a substantially elliptical shape that bulges greatly in the width direction of the ridge portion 22. Further, the reflective film 30B has a curved shape that covers the top of the substantially wedge-shaped ridge portion 22D so as to wrap it. Further, the reflective film 30C has a curved shape that covers the top of the trapezoidal ridge portion 22A so as to wrap it. The coverage rate Rc of one side surface 22b of the ridge portion 22 by these reflective films 30B and 30C and the coverage rate Rc of the other side surface 22b are substantially the same.

[0149] Further, the reflective film 30D covers the top of the substantially wedge-shaped ridge portion 22D so as to wrap it, but is unevenly distributed on one side surface 22b (the left side surface 22b shown in FIG. 6) side of the ridge portion 22. Specifically, the reflective film 30D covers a wide range of the left side surface 22b of the ridge portion 22, and its coverage rate Rc is about 80%. On the other hand, the reflective film 30D covers only a narrow range on the upper side of the right side surface 22b, and its coverage rate Rc is about 25%. Thus, the coverage rate Rc by 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. Preferred range of coverage rate Rc of ridge portion by reflective film> Next, the preferred range of the coverage rate Rc of the side surface 22b of the ridge portion 22 by the reflective film 30 according to the present embodiment will be described.

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

[0152] Rc[%]=(Hx / H)×100 ···(1) H: Height of the rib portion 22 in the Z direction Hx: Height of the portion of the side surface 22b of the rib portion 22 covered by the reflective film 30 in the Z direction

[0153] Also, the opening rate Rr is the ratio of the height (H - Hx) of the portion of the side surface 22b of the rib portion 22 not covered by the reflective film 30 to the height (H) of the rib portion 22 shown in FIGS. 1 and 5. The opening rate Rr is represented by the following formula (2).

[0154] Rr[%]=((H - Hx) / H)×100 ···(2)

[0155] According to the above definitions, Rr = 100 - Rc. Therefore, when the coverage rate Rc of the side surface 22b of the rib portion 22 by the reflective film 30 is 25% or more and 80% or less, the opening rate Rr of the side surface 22b of the rib 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 the present embodiment, it is preferable that the coverage rate Rc of the side surface 22b of the rib portion 22 by the reflective film 30 is 25% or more and 80% or less (that is, the opening rate Rr is 20% or more and 75% or less). Specifically, in the present embodiment, the reflective film 30 is formed to cover the tip 22a and the upper sides of both side surfaces 22b of the rib portion 22 and to be open without covering the lower sides of both side surfaces 22b. And the coverage rate 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 such a configuration, the polarizing element 1 according to the present embodiment can exhibit sufficient transmittance even for obliquely incident light with a large incident angle θ (for example, 45 to 60°). For example, when the obliquely incident light is separated into S-polarized light (reflected light) and P-polarized light (transmitted light) by the polarizing element 1, regardless of the incident angle θ of the obliquely incident light, the transmittance Tp of the P-polarized light (transmitted light) transmitted through the polarizing element 1 can be maintained at a high value. Further, by setting the coverage ratio Rc to 25% or more and 80% or less, while maintaining the contrast (CR = Tp / Ts), which is the ratio of the transmittance axis transmittance (Tp) to the transmittance axis reflectance (Ts), at a good level, the reflection action by the reflection film 30 described above can be more surely exhibited without depending on the incident angle θ. Therefore, regardless of the incident angle θ of the obliquely incident light, high transmittance of the transmitted light can be ensured, and the polarization separation characteristics can be improved.

[0158] On the other hand, as a comparative example, when the reflection film 30 is formed so as to cover only the tip 22a of the ridge portion 22 of the grid structure 20, or when it is formed so as to cover the entire tip 22a and one side surface 22b of the ridge portion 22, it is considered that the variation in the transmittance Tp becomes large depending on the incident angle θ of the obliquely incident light, and sufficient transmittance cannot be obtained even for obliquely incident light with a large incident angle θ. Further, as a comparative example, when the reflection film 30 covers all of the tip 22a and both side surfaces 22b of the ridge portion 22 of the grid structure 20 (when the coverage ratio Rc is 100%), the transmittance significantly decreases as the incident angle θ of the obliquely incident light increases.

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

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

[0161] When the coverage ratio Rc is less than 25%, the transmission axis transmittance Tp of the P-polarized light transmitted through the polarization element 1 decreases, and the transmittance Tp varies depending on the incident angle θ, and a sufficiently high value of Tp×Rs cannot be obtained. Therefore, for obliquely incident light with a large incident angle θ, sufficient transmittance of the transmitted light and polarization separation characteristics represented by Tp×Rs cannot be obtained. On the other hand, when the coverage ratio Rc is more than 80%, similar to the case of covering all of the tip 22a and both side surfaces 22b of the ridge portion 22 of the grid structure 20, as the incident angle θ of the obliquely incident light increases (for example, 45 to 60°), the transmission axis transmittance Tp decreases, so that the variation in the transmittance Tp becomes large depending on the incident angle θ.

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

[0163] From the same perspective, it is more preferable that the coverage ratio Rc is 30% or more and 70% or less (that is, the opening ratio Rr is 30% or more and 70% or less). Thereby, in the case of the above-mentioned oblique incidence condition, a high transmittance Tp of 80% or more can be obtained, and a high Tp×Rs of 72% or more can be obtained. Further, it is more preferable that the coverage ratio Rc is 30% or more and 60% or less (that is, the opening ratio Rr is 40% or more and 70% or less). Thereby, in the case of the above-mentioned oblique incidence condition, 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 ratio Rc is 40% or more and 50% or less (that is, the opening ratio Rr is 50% or more and 60% or less). Thereby, in the case of the above-mentioned oblique incidence condition, a very high transmittance Tp of 85% or more can be obtained, and a very high Tp×Rs of 77% or more can be obtained.

[0164] Regarding the reflectance Rs of the reflection axis, it is preferable that the coverage ratio Rc is 20% or more. Thereby, in the case of the above-mentioned oblique incidence condition, a high reflectance Rs of 85% or more can be obtained.

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

[0166] <2.7. Preferred range of Tp×Rs> Next, the preferred range of "Tp×Rs", which is an index representing the polarization separation characteristics of the wire grid polarizing element 1 according to the present embodiment, will be described.

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

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

[0169] When the wire grid polarizing element 1 according to the present 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 arranged to be inclined by a predetermined angle (for example, 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 about 45° obliquely, the incident light is separated by the polarization element 1 into the first polarization (S-polarization: reflected light) and the second polarization (P-polarization: transmitted light). The S-polarized light is light having an electric field component in a direction parallel to the longitudinal direction of the ridge portion 22 of the grid structure 20 (reflection axis direction: Y direction shown in FIG. 2) among the incident light. On the other hand, the P-polarized light is light having an electric field component in a direction parallel to the width direction of the ridge portion 22 of the grid structure 20 (transmission axis direction: X direction shown in FIG. 2) among the incident light.

[0170] The S-polarized light in the reflection axis direction mainly becomes reflected light reflected by the reflection film 30 of the polarization 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 ratio of the S-polarized light reflected by the polarization element 1 among the S-polarized light incident on the polarization element 1. Note that the reflection axis transmittance (Rp) represents the ratio of the S-polarized light transmitted through the polarization element 1 among the S-polarized light incident on the polarization element 1.

[0171] On the other hand, the P-polarized light in the transmission axis direction mainly becomes transmitted light transmitted through the transparent grid structure 20 and the substrate 10 of the polarization 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 ratio of the P-polarized light transmitted through the polarization element 1 among the P-polarized light incident on the polarization element 1. Note that the transmission axis reflectance (Ts) represents the ratio of the P-polarized light reflected by the polarization element 1 among the P-polarized light incident on the polarization 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. Thus, the higher the value of Tp×Rs, which is the product of Tp and Rs, the higher both the transmittance of P-polarized light (transmitted light) and the reflectivity of S-polarized light (reflected light), and the better the polarization separation characteristics as a polarization beam splitter.

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

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

[0175] Furthermore, it is more preferable that Tp×Rs is 72% or more, still more preferable that it is 75% or more, and particularly preferable that it is 80% or more. Thereby, the light utilization efficiency as described above, and the brightness and visibility of the displayed image can be further improved.

[0176] <2.8. Preferred Range of Height H of Ridge Portion> When incident light is incident on the polarization element 1 according to the present embodiment at a relatively large incident angle θ (for example, 45°), the height H (see FIGS. 1, 3, etc.) of the convex strip 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. Thereby, a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and high contrast CR of transmitted light can be obtained.

[0177] Specifically, regarding the transmittance, when the height H of the convex strip portion 22 is 160 nm or more, the transmission axis transmittance Tp of obliquely incident light becomes 80% or more, and a high transmittance can be obtained. Furthermore, when H is 180 nm or more, Tp of 85% or more can be obtained, which is more preferable. In addition, when H is 220 nm or more, Tp of 87% or more can be obtained, which is particularly preferable.

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

[0179] Also, regarding the contrast CR of transmitted light (CR = Tp / Ts), the height H of the convex strip portion 22 may be 100 nm or more, but when H is 160 nm or more, excellent contrast CR of 150 or more can be obtained. Furthermore, when H is 180 nm or more, excellent CR of 250 or more can be obtained, which is more preferable. In addition, when H is 220 nm or more, excellent CR of 500 or more can be obtained, which is particularly preferable.

[0180] As described above, it can be understood that in order to improve various characteristics (Tp, Tp×Rs, CR) of the polarization element 1, particularly Tp, it is preferable that the height H of the ridge portion 22 is larger. The reason is considered as follows. That is, when the film formation incident angle φ (see Fig. 5) when forming the reflective film 30 on the ridge portion 22 by sputtering or evaporation is the same, the lower the height H of the ridge portion 22, the larger the coverage rate Rc by the reflective film 30. When the coverage rate Rc increases, the range of the ridge portion 22 covered by the reflective film 30 becomes wider, so it becomes difficult for P-polarized light to pass through the grid structure 20, and the transmittance Tp decreases. Therefore, under the condition that the film formation incident angle φ is the same, it can be said that it is preferable to increase the height H of the ridge portion 22 to reduce the coverage rate Rc and increase the transmittance Tp.

[0181] <2.9. Preferred range of the tip thickness Dt of the functional film (reflective film)> When incident light is incident on the polarization element 1 according to the present embodiment at a relatively large incident angle θ (for example, 45°), the thickness Dt of the reflective film 30 covering the tip 22a of the ridge portion 22 of the grid structure 20 (the 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 the obliquely incident light will be 85% or more, and a high transmittance can be obtained. Furthermore, considering the Tp characteristics and the Tp×Rs characteristics required for a polarization beam splitter, it is more preferable that Dt is 15 nm or more.

[0183] <2.10. Preferred range of the side thickness Ds of the functional film (reflective film)> Further, the thickness Ds of the reflective film 30 covering the side surface 22b of the rib portion 22 of the grid structure 20 (the side 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. Thereby, a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and a high contrast CR of transmitted light can be obtained.

[0184] Specifically, regarding the transmittance, 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 the obliquely incident light becomes 80% or more, and a high transmittance can be obtained. Further, 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] Also, regarding the reflectance, when the side thickness Ds of the reflective film 30 is 10 nm or more, the reflectance Rs of the reflection axis of the obliquely incident light becomes 80% or more, and a high reflectance can be obtained. Further, when 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 polarization beam splitter (PBS), when the side thickness Ds of the reflective film 30 is 12.5 nm or more and 30 nm or less, excellent Tp×Rs of 70% or more can be obtained. Further, when Ds is 15 nm or more and 25 nm or less, Tp×Rs of 76% or more can be obtained, which is more preferable.

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

[0188] <2.11. Uneven distribution of the reflective film> In addition, in the polarization element 1 according to the present embodiment, the reflective film 30 covering the convex strip portion 22 may be unevenly distributed on one side of the convex strip portion 22 to form a left-right asymmetric shape in the width direction (X direction) of the convex strip portion 22. Specifically, between one side surface 22b and the other side surface 22b of the convex strip portion 22, the side surface thickness Ds, the coverage rate Rc, etc. of the reflective film 30 may be changed so that the reflective film 30 is unevenly distributed on one side surface 22b of the convex strip portion 22. That is, the reflective film 30 may be configured to thickly and widely cover one side surface 22b of the convex strip portion 22 and thinly and narrowly cover the other side surface 22b.

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

[0190] Note that an incident angle of +θ means that obliquely incident light is incident from a direction inclined to one side in the X direction (the width direction of the convex strip portion 22) with respect to the convex strip portion 22. On the other hand, an incident angle of -θ means that obliquely incident light is incident from a direction inclined to the other side in the X direction with respect to the convex strip portion 22.

[0191] As described above, when the reflective film 30 is unevenly distributed on one side of the convex strip portion 22, it is preferable that the difference between Tp(+) and Tp(-) is within 3%. Thereby, even when the reflective film 30 is unevenly distributed on one side of the convex strip portion 22, a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and a high contrast CR of transmitted light can be obtained.

[0192] Specifically, regarding the transmittance, even when the reflective film 30 is unevenly distributed on one side, the transmission axis transmittance Tp of obliquely incident light with incident angles θ of +45° and -45° is 85% or more, and a high transmittance can be obtained.

[0193] Also, regarding the reflectance, even when the reflective film 30 is unevenly distributed on one side, the axial reflectance Rs of the obliquely incident light with the incident angle θ of +45° and -45° becomes 85% or more, and a high reflectance can be obtained.

[0194] Also, regarding the Tp×Rs characteristics required for a polarizing beam splitter (PBS), even when the reflective film 30 is unevenly distributed on one side, the Tp×Rs of the obliquely incident light with the incident angle θ of 45° becomes 75% or more, and excellent Tp×Rs characteristics can be obtained.

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

[0196] <2.12. Other components> The polarizing element 1 according to the present 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, it is preferable that the polarizing element 1 further includes a protective film 40 formed so as to cover at least the surface of the reflective film 30. Specifically, as shown in FIG. 7, it is more preferable that the protective film 40 covers the entire surface of the grid structure 20. That is, it is more preferable that the protective film 40 is formed so as to cover the side surface 22b of the ridge portion 22 and the surface of the base portion 21 of the grid structure 20 and the surface of the reflective film 30. By forming such a protective film 40, the scratch resistance, antifouling property, and waterproof property of the polarizing element 1 can be further enhanced.

[0198] Furthermore, it is more preferable that the protective film 40 further includes a water-repellent coating or an oil-repellent coating. Thereby, the antifouling property and waterproof property of the polarizing element 1 can be further enhanced.

[0199] The material constituting the protective film 40 is not particularly limited as long as it can enhance the scratch resistance, antifouling property, and waterproof property of the polarizing element 1. Examples of the material constituting the protective film 40 include a film made of a dielectric material, and more specifically, an inorganic oxide, a silane-based water-repellent material, etc. Examples of the inorganic oxide include Si oxide, Hf oxide, etc. The silane-based water-repellent material may contain a fluorine-based silane compound such as perfluorodecyltriethoxysilane (FDTS), or may contain a non-fluorine-based silane compound such as octadecyltrichlorosilane (OTS).

[0200] Among these materials, it is more preferable to include 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 enhanced, and when it contains a fluorine-based water-repellent material, the antifouling property and waterproof property of the polarizing element can be further enhanced.

[0201] Note that the protective film 40 only needs to be formed so as to cover at least the surface of the reflective film 30, but as shown in FIG. 7, it is more preferably 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 figure of FIG. 7, the protective film 40 may cover the end face (the end face of the base portion 21) of the grid structure 20, or as shown in the lower figure of FIG. 7, the protective film 40 does not have to cover the end face (the end face of the base portion 21) of the grid structure 20. Also, as shown in FIG. 8, the protective film 40 can 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, and thus the heat dissipation property of the polarizing element 1 is further improved.

[0202] Furthermore, as shown in FIG. 9, it is preferable that a heat radiating member 50 is provided so as to surround the periphery of the substrate 10 in the polarizing element 1 according to the present embodiment. With this heat radiating member 50, the heat transmitted from the substrate 10 can be released more efficiently. Here, the heat radiating member 50 is not particularly limited as long as it is a member having a high heat radiating effect. The heat radiating member 50 may be, for example, a radiator, a heat sink, a heat spreader, a die pad, a heat pipe, a metal cover, a housing, or the like.

[0203] <2.13. Image of the actual grid structure> Next, with reference to FIG. 10, an example in which the polarizing element 1 according to the present embodiment is actually manufactured and magnified by using a scanning electron microscope (SEM) will be described. FIG. 10A is an SEM image of the grid structure 20 before being covered with the reflective film 30 as viewed from an oblique direction. FIG. 10B is an SEM image showing a cross section of the ridge portion 22 of the grid structure 20 before being covered with the reflective film 30. FIG. 10C is an SEM image showing a cross section of the ridge portion 22 of the grid structure 20 covered with the reflective film 30.

[0204] As shown in FIGS. 10A and 10B, the grid structure 20 is formed with a base portion 21 provided along the surface of the substrate 10 and a ridge portion 22 protruding from the base portion 21. The plurality of ridge portions 22 are arranged at substantially equal pitches P. Each ridge portion 22 has a tapered shape in which the width becomes narrower as it moves away from the base portion 21. The width W of the top of the ridge portion 22 T is narrower than the width W of the bottom of the ridge portion 22 B . The pitch P is sufficiently larger than the width W of the bottom of the ridge portion 22 B . The height H of the ridge portion 22 is larger than the pitch P. In the example of FIG. 10, P = 140 nm, W T = 10 nm, W B = 30 nm, and H = 220 nm. Further, as shown in FIG. 10C, the reflective film 30 is formed so as to cover and wrap the tip 22a and both side surfaces 22b of the ridge portion 22. The outer surface of the reflective film 30 is rounded and curved, and bulges in the width direction of the ridge portion 22.

[0205] <3. Method for manufacturing a polarizing element> Next, with reference to FIG. 11, a method for manufacturing the wire grid polarizing element 1 according to the present embodiment will be described. FIG. 11 is a process diagram showing the method for manufacturing the wire grid polarizing element 1 according to the present embodiment.

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

[0207] As shown in FIG. 11, the method for manufacturing the wire grid polarizing element 1 according to the present embodiment includes a grid structure material forming step (S10), a nanoimprint step (S12), a grid structure forming step (S14), and a reflective film forming step (S16).

[0208] Grid structure material forming step (S10) First, in S10, a grid structure material 23 made of a transparent organic material (for example, an ultraviolet curable resin or a thermosetting resin) is laminated on a substrate 10 made of a transparent inorganic material (for example, glass) by coating or the like. As the inorganic material of the substrate 10, various materials described above can be used. Also, as the organic material of the grid structure 20, various materials described above can be used. Further, the film thickness of the grid structure material 23 may be appropriately adjusted according to the dimensions of the base portion 21 and the ridge portion 22 of the grid structure 20 formed by the nanoimprint in S20.

[0209] Nanoimprint step (S12) and grid structure forming step (S14) Next, in S12, by performing nanoimprinting on the grid structure material 23, in S14, the grid structure 20 is formed on the substrate 10. The grid structure 20 is a fine concavo-convex structure in which a base portion 21 provided on the substrate 10 and a plurality of convex strip portions 22 protruding from the base portion 21 are integrally formed. The fine concavo-convex structure is a structure having fine convex portions and concave portions on the order of, for example, several nm to several tens of nm.

[0210] In the nanoimprinting step of S12, using a master disk 60 on which an inverted shape of the fine concavo-convex shape of the grid structure 20 is formed, the fine concavo-convex shape of the master disk 60 is transferred to the surface of the grid structure material 23 (S12). Thereby, an uneven pattern composed of the base portion 21, the convex strip portion 22, and the concave portion 24 is formed on the grid structure material 23. Further, in the nanoimprinting step, together with the transfer of the uneven pattern, the grid structure material 23 on which the uneven pattern is transferred is cured by irradiating the grid structure material 23 with energy rays to form the grid structure 20 (S14). For example, when the grid structure material 23 is made of an ultraviolet curable resin, the ultraviolet curable resin on which the uneven pattern is transferred may be cured by irradiating the grid structure material 23 with ultraviolet rays using an ultraviolet irradiation device 66. Alternatively, when the grid structure material 23 is made of a thermosetting resin, the thermosetting resin on which the uneven pattern is transferred may be cured by heating the grid structure material 23 using a heating device 68 such as a heater.

[0211] In the above steps S12 and S14, as the convex strip portion 22 of the grid structure 20, a convex strip portion 22 having a tapered shape in which the width becomes narrower as it moves away from the base portion 21 is formed. The convex strip portion 22 in the example of FIG. 11 is trapezoidal (tapered), but may have various other tapered shapes as shown in FIG. 3.

[0212] Thus, in this embodiment, in the nanoimprinting step S12, since the rib portion 22 having a tapered shape is imprinted, the master disk 60 can be easily peeled off from the grid structure material 23, and the mold release property is excellent. Further, the rib portion 22 of the grid structure 20 can be accurately formed into a desired shape without causing mold collapse.

[0213] Reflective film forming step (S16) Next, in S16, a reflective film 30 that covers a part of the rib portion 22 of the grid structure 20 is formed using a metal material such as Al or Ag. The reflective film 30 is an example of a functional film that imparts a predetermined function to the polarization element 1. The reflective film 30 is a metal thin film (grid of metal fine wires) for reflecting incident light incident on the grid structure 20 of the polarization 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 as to cover and wrap the tip 22a and at least the upper side of one side surface 22b of the rib portion 22, and not to cover the lower sides of both side surfaces 22b of the rib portion 22 and the base portion 21. Further, the surface of the reflective film 30 that covers and wraps the rib portion 22 is formed to have a rounded shape and bulge in the width direction of the rib portion 22. In addition, the maximum width W MAX (grid maximum width W MAX ) of the reflective film 30 that covers and wraps the rib portion 22 is made to be equal to or greater than the width W B (grid bottom width W B ) of the bottom of the aforementioned rib portion, and the reflective film 30 is formed.

[0215] As a method for forming such a reflective film 30, for example, as shown in FIG. 5, sputtering or vapor deposition can be used. The metal material is alternately sputtered or vapor deposited on the rib portion 22 of the grid structure 20 from an oblique direction to form the reflective film 30. Thereby, the reflective film 30 having a desired shape can be suitably formed so as to roundly cover the top of the rib portion 22.

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

[0217] In addition, the manufacturing method of the polarization element 1 according to the present embodiment may include a step of forming a protective film 40 (protective film forming step) for covering the surface of the polarization element 1 as necessary 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. As the material of the protective film 40, the various materials described above can be used.

[0218] As described above, the manufacturing method of the polarization element 1 according to the present embodiment has been described. By going through the above-described steps, a polarization element 1 excellent in polarization characteristics and heat dissipation can be manufactured without causing an increase in the manufacturing cost and complexity of the manufacturing of the polarization element 1.

[0219] Here, in order to compare with the manufacturing method according to the present embodiment, with reference to FIG. 12, the manufacturing method of a conventional wire grid polarization element will be briefly described.

[0220] As shown in FIG. 12, in the manufacturing method of a conventional wire grid polarization element, first, in order to form a convex grid shape, a metal film 80 is formed on a substrate 10 (S20). In this S20, on a substrate 10 made of an inorganic material such as glass, a reflective film made of a material that reflects light in the used band, for example, a metal film 80 such as aluminum, is formed using sputtering or evaporation or the like.

[0221] Next, using photolithography technology, a resist mask 70 is patterned on the metal film 80 (S22). Then, by etching the metal film 80 using a vacuum dry etching apparatus or the like, a convex shape made of the metal film 80 is formed (S24). For example, at this time, if the etching selectivity between the resist mask 70 and the metal film 80 cannot be achieved, an oxide film such as SiO2 is further formed on the metal film 80 by sputtering or the like, and the resist mask 70 is formed thereon by photolithography technology. Then, after peeling the resist mask 70 from the metal film 80 (S26), a protective film 40 made of an SiO2 film or the like is formed by CVD or the like, and a water-repellent and oil-repellent coating treatment is also performed as necessary (S28).

[0222] In the steps S20 to S28 of the above conventional manufacturing method, a process for manufacturing a reflective wire grid polarizing element having a basic configuration is shown. However, considering the case where the metal film 80 is a multilayer film, a more complicated process is required. Therefore, it is presumed that the conventional wire grid polarizing element manufactured by the process shown in S20 to S28 of FIG. 12 has a high manufacturing cost and a long manufacturing time. In addition, when mass-producing the polarizing element, in order to form a fine convex shape smaller than the wavelength of light, it is necessary to prepare a plurality of high-precision and expensive etching apparatuses and photolithography apparatuses according to the production volume, and it is predicted that the capital investment will also be higher.

[0223] On the other hand, the manufacturing method of the polarizing element 1 according to the present embodiment (see FIG. 11) uses an imprint technology such as nanoimprint to form the grid structure 20. Therefore, compared with the above conventional manufacturing method (see FIG. 12), the manufacturing cost, manufacturing time, and capital investment can be significantly reduced.

[0224] In the manufacturing method of the polarization element 1 according to this embodiment, nanoimprinting is performed on the grid structure material 23 (S12 in FIG. 11), but the conditions of nanoimprinting are not particularly limited. For example, as shown in S12 of FIG. 11, a replica master (or a mold master) is used as the master disk 60, and while performing nanoimprinting, UV irradiation, heating, etc. are performed on the grid structure material 23, and the grid structure material 23 is cured in a state where the concavo-convex pattern is imprinted. Then, the master disk 60 is released from the cured grid structure material 23. Thereby, the grid structure 20 having the base portion 21 and the ridge portion 22 can be formed by transfer.

[0225] Note that the master disk 60 used in the nanoimprinting step S12 (FIG. 11) in the manufacturing method of the polarization element 1 according to this embodiment can be manufactured by, for example, photolithography technology as shown in FIG. 13. FIG. 13 is a process diagram showing the manufacturing method of the master disk 60 according to this embodiment.

[0226] As shown in FIG. 13, first, after forming the master disk metal film 62 on the master disk base material 61 (S30), a resist mask 70 is formed on the master disk metal film 62 (S32). Next, the master disk metal film 62 is etched using the resist mask 70, and a concave groove 65 corresponding to the ridge portion 22 of the grid structure 20 is formed in the etched master disk metal film 62 (S34).

[0227] Thereafter, the master disk 60 is obtained by peeling the resist mask 70 from the master disk metal film 62 (S36). The master disk 60 has a fine concavo-convex structure composed of a plurality of convex portions 63 and concave grooves 65 formed on the master disk base material 61. The fine concavo-convex structure on the surface of the master disk 60 has an inverted shape of the fine concavo-convex structure on the surface of the grid structure 20 of the polarization element 1. The concave groove 65 of the master disk 60 has an inverted shape of the ridge portion 22 of the grid structure 20, and the convex portion 63 of the master disk 60 has an inverted shape of the concave portion 24 between the ridge portions 22 of the grid structure 20.

[0228] Furthermore, the manufacturing method according to the present embodiment may include a step (S38) of forming a release film coat 64 on the surface of the fine uneven structure of the master disk 60 as necessary. By providing the release film coat 64 on the surface of the master disk 60, after performing nanoimprinting on the grid structure material 23 in the nanoimprinting step (S12) shown in FIG. 11 above, the master disk 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, with reference to FIG. 14, a projection display device to which the wire grid polarizing element 1 according to the present embodiment is applied will be described.

[0230] The projection display device according to the present embodiment includes the wire grid polarizing element 1 according to the present embodiment described above. By providing the projection display device according to the present embodiment with the polarizing element 1, excellent polarization characteristics, heat resistance, heat dissipation, etc. of the polarizing element 1 can be realized.

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

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

[0233] As shown in FIG. 14, the head-up display device 100 according to the present embodiment includes the wire grid polarizing element 1 according to the present embodiment described above. By providing the head-up display device 100 with the polarizing element 1, the polarization characteristics, heat resistance, and heat dissipation can be improved. A conventional head-up display incorporating a polarizing element is considered to have insufficient heat resistance in view of long-term use and compatibility with future high brightness and enlarged display because of its poor heat dissipation.

[0234] As shown in FIG. 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 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 front glass or a combiner of the vehicle. The vehicle head-up display device is, for example, an image display device that is disposed on a dashboard of the vehicle, projects image light onto the front glass (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 front glass surface (display surface 5). For this reason, sunlight may enter in the direction opposite to the emission direction of the display image and enter the display element 3. In the head-up display device 100 according to the present embodiment, a reflector 4 for reflecting and enlarging the display image is provided for the purpose of miniaturization and enlargement of the display image. In such a case, in a conventional head-up display device, sunlight incident on the reflector from the outside is condensed in the vicinity of the display element, which may cause deterioration or failure of the display element due to heat.

[0237] On the other hand, in the head-up display device 100 according to the present embodiment, for the purpose of preventing the incidence of sunlight on the display element 3, the hybrid polarizing element 1 having excellent heat dissipation and heat resistance as described above is provided. This polarizing element 1 can stably exhibit the polarizing function even at a high temperature of about 200°C. Therefore, for example, even in a high-temperature environment such as inside a car in summer, the sunlight incident on the reflector 4 from the outside can be shielded by the polarizing element 1 to prevent it from reaching the display element 3, so that the deterioration and failure of the display element 3 can be suppressed.

[0238] Note that the components of the head-up display device 100 shown in FIG. 14 are examples of basic components, and the components of the projection display device are not limited to the example of FIG. 14, and other components can be appropriately provided according to the required performance and the like.

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

[0240] In addition, the arrangement of the wire grid polarizing element in the projection display device is not limited to the example of the arrangement of the polarizing element 1 in the head-up display device 100 shown in FIG. 14, and can be appropriately selected and changed according to the configuration of the projection display device and the required performance. For example, although not shown, the polarizing element 1 can be disposed between the display element 3 and the light source 2. Also, although not shown, the polarizing element 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 constituted by the polarizing element 1.

[0241] Further, although not shown, a heat radiating member 50 (see FIG. 9) may be provided around the polarizing element 1 installed in the head-up display device 100. By this heat radiating member 50, the heat dissipation property of the polarizing element 1 can be further improved, so that the polarization characteristics and heat resistance of the polarizing element 1 can be further improved.

[0242] <4.2. Projection display device including a polarizing beam splitter> Next, with reference to FIGS. 15 to 17, a projection display device using the reflective wire grid polarizing element 1 according to the present embodiment as a polarizing beam splitter 230 will be described. Hereinafter, first, matters common to three specific examples of the projection display devices 200A, 200B, and 200C (hereinafter, may also be collectively referred to as "projection display device 200") shown in FIGS. 15 to 17 will be comprehensively described. Thereafter, each specific example shown in FIGS. 15 to 17 will be individually described.

[0243] As shown in FIGS. 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. Note that a retardation compensation plate (not shown) may be provided between the polarizing beam splitter 230 and the reflective liquid crystal display element 240.

[0244] The light source 210 may be a point light source having one light emitting portion, or may be a light source having a plurality of light emitting portions such as LEDs. Further, the light emitted from the light source 210 may be parallel light or diffused light. Therefore, the light of the light source 210 may be incident on the polarizing beam splitter 230 (reflective wire grid polarizing plate) at an incident angle θ within a predetermined range centered on, for example, 45° (for example, a range of 45° ± 15°).

[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 P polarization or S polarization.

[0246] The polarization beam splitter 230 is composed of a reflective wire grid polarizer. The reflective wire grid polarizer is an example of the wire grid polarizing element 1 according to the present embodiment. The polarization beam splitter 230 is arranged such that the light from the light source 210 is incident at an incident angle θ within a predetermined range including 45°. This predetermined range of the incident angle θ is, for example, 45° ± 15° described above, that is, 30° or more and 60° or less.

[0247] For example, in FIGS. 15 to 17, the polarization beam splitter 230 is arranged to be inclined by 45° with respect to the incident direction of the incident light so that the incident light from the light source 210 is mainly incident on the polarization beam splitter 230 at an incident angle θ of 45°. Also, the polarization beam splitter 230 is arranged to be inclined by 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 mainly incident on the polarization beam splitter 230 at an incident angle θ of 45°.

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

[0249] When reflecting desired polarization by the polarization beam splitter 230, the polarization beam splitter 230 is arranged such that light including the polarization to be reflected is incident on the surface of the polarization beam splitter 230 (i.e., the uneven surface on the side where the grid structure 20 of the polarization element 1 is formed). For example, as shown in FIG. 15, when reflecting the S polarization incident from the PS converter 220 by the polarization beam splitter 230, the surface of the polarization beam splitter 230 may be directed toward the PS converter 220 side that emits the S polarization. On the other hand, as shown in FIG. 16, when reflecting the S polarization incident from the reflective liquid crystal display element 240 by the polarization beam splitter 230, the surface of the polarization beam splitter 230 may be directed toward the reflective liquid crystal display element 240 side that emits the S polarization.

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

[0251] Also, as shown in FIGS. 15 and 17, the reflective liquid crystal display element 240 reflects and modulates the incident first polarization (S polarization) and emits a second polarization (P polarization) representing a display image. However, it is not limited to such an example. As shown in FIG. 16, the reflective liquid crystal display element 240 may reflect and modulate the incident second polarization (P polarization) and emit a first polarization (S polarization) representing a display image.

[0252] The lens 250 enlarges 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 polarization 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 polarization beam splitter 230 and is incident on 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 polarization beam splitter 230 and is incident on the lens 250.

[0253] As described above, in the projection display device 200 according to the present embodiment, the wire grid polarizing element 1 according to the present embodiment described above is used as the polarization beam splitter 230. Therefore, the polarization beam splitter 230 is excellent in the reflectivity of S-polarized light, the transmissivity of P-polarized light, and the Tp×Rs characteristics with respect to obliquely incident light having a relatively large and wide incident angle θ (for example, 30 to 60°), and is excellent in the characteristic of separating obliquely incident light into P-polarized light and S-polarized light.

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

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

[0256] The light emitted from the light source 210 is non-polarized and contains P-polarized components and S-polarized components in the same ratio. Therefore, if only one polarization is selected and extracted by the polarization beam splitter 230 composed of the polarization element 1, the light quantity will be reduced by about half. Thus, the PS converter 220 converts the light emitted from the light source 210 into either the first polarization (S-polarization) or the second polarization (P-polarization). Thereby, it is possible to suppress the decrease in the light quantity of the polarized light extracted by the polarization beam splitter 230 and improve the light utilization efficiency. For example, the PS converter 220 shown in FIG. 15 converts the light from the light source 210 into the first polarization (S-polarization).

[0257] The light converted to S-polarization by the PS converter 220 is incident on the polarization beam splitter 230 disposed obliquely at about 45°. The polarization beam splitter 230 reflects the first polarization (S-polarization) and emits it toward the reflective liquid crystal display element 240 at an emission angle of 45°. The reflective liquid crystal display element 240 modulates and reflects the first polarization (S-polarization) to generate a second polarization (P-polarization) representing the display image, and emits the second polarization (P-polarization) toward the polarization beam splitter 230. The second polarization (P-polarization) passes through the polarization beam splitter 230, is enlarged by the lens 250, and then is projected onto a display surface (not shown) to display the display image.

[0258] The projection display device 200A having the above configuration includes, as the polarization beam splitter 230, a reflective wire grid polarizing plate composed of the wire grid polarizing element 1 according to the present embodiment. Thereby, the polarization separation characteristics of the polarization beam splitter 230 can be improved for obliquely incident light and light incident at a wide incident angle θ, and the heat dissipation and heat resistance of the polarization beam splitter 230 and the projection display device 200A can be improved.

[0259] On the other hand, a projection display device (not shown) equipped with a conventional polarization element as a polarization beam splitter has poor heat dissipation performance of the polarization element. For this reason, from the viewpoints of long-term use, high brightness, and large-screen display, it is considered that the heat resistance is not sufficient. In addition, the incident angle θ of the light incident on the polarization beam splitter is not only 45°, but also any angle within a predetermined range centered on 45° (for example, about 45° ± 15°). Thus, even when obliquely incident light with a large and wide range of incident angles θ is incident on the polarization beam splitter, the polarization beam splitter is required to have the performance of preferably separating the obliquely incident light into S-polarized light and P-polarized light regardless of the incident angle θ. However, in a polarization beam splitter using a conventional polarization element, the polarization separation characteristics for the above obliquely incident light are poor, so that the light utilization efficiency deteriorates, and adverse effects on the image quality of a display image such as brightness unevenness have been a problem.

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

[0261] In addition, the projection display device is not limited to the example of the projection display device 200A shown in FIG. 15 above. For example, like the projection display device 200B shown in FIG. 16 or the projection display device 200C shown in FIG. 17, the components and arrangements of the projection display device can be appropriately changed.

[0262] As shown in FIG. 16, the projection display device 200B according to the second specific example of the present embodiment includes a light source 210, a PS converter 220, a polarization 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 the light from the light source 210 into the second polarization (P-polarization). The light converted into P-polarization by the PS converter 220 passes through the polarization beam splitter 230 disposed obliquely at about 45° and is incident on the reflective liquid crystal display element 240. The reflective liquid crystal display element 240 modulates and reflects the second polarization (P-polarization) to generate the first polarization (S-polarization) representing the display image, and emits the first polarization (S-polarization) toward the polarization beam splitter 230. The polarization beam splitter 230 reflects the first polarization (S-polarization) and emits it toward the lens 250 at an emission angle of 45°. The first polarization (S-polarization) is enlarged by the lens 250 and then projected onto a display surface (not shown), and the display image is displayed.

[0264] Similar to the above-described projection display device 200A (see FIG. 15), the projection display device 200B having the above configuration has excellent polarization separation characteristics with respect to obliquely incident light, can improve the light utilization efficiency, reduce luminance unevenness, etc., and improve the image quality of the display image.

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

[0266] In the projection display device 200C, the non-polarized light emitted from the light source 210 is directly incident on the polarization beam splitter 230 disposed obliquely at about 45°. The polarization beam splitter 230 reflects the component of the first polarization (S-polarization) in the non-polarized light and emits it toward the reflective liquid crystal display element 240 at an emission angle of 45°. On the other hand, among the non-polarized light incident on the polarization beam splitter 230, the component of the second polarization (P-polarization) passes through the polarization beam splitter 230 and is incident on the light absorber 260. Since most of the component of the second polarization (P-polarization) is absorbed by the light absorber 260, it is possible to suppress unnecessary second polarization (P-polarization) from being incident on other optical systems in 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 polarization beam splitter 230 to generate the second polarized light (P polarized light) representing the display image, and emits the second polarized light (P polarized light) toward the polarization beam splitter 230. The second polarized light (P polarized light) passes through the polarization beam splitter 230, is enlarged by the lens 250, and then is projected onto a display surface (not shown), and the display image is displayed.

[0268] In the projection display device 200C having the above configuration, since the PS converter 220 is not installed, among the non-polarized light emitted from the light source 210, the component of the second polarized light (P polarized light) is absorbed by the light absorber 260 and not used for displaying the display image. For this reason, the light amount of the display image is reduced to about half. However, since the cost and installation space required for the PS converter 220 can be reduced, and the number of components of the projection display device 200C can be reduced, there is an advantage that the cost of the projection display device 200C can be reduced and the projection display device 200C can be miniaturized.

[0269] As described above, a specific example of the projection display device 200 using the reflective wire grid polarizing element 1 according to the present embodiment as the polarization beam splitter 230 has been described. Note that the projection display device is not limited to the specific examples of the projection display device 200 shown in FIGS. 15 to 17, and the components and arrangements of the projection display device may be appropriately changed according to required performance and the like, or other components may be appropriately provided.

[0270] <5. Vehicle> Next, a vehicle equipped with the video display device according to the present embodiment will be described.

[0271] The vehicle according to this embodiment (not shown) includes a projection display device having the wire grid polarizing element 1 according to the above-described embodiment. The vehicle may be various automobiles such as a passenger car, a light automobile, a bus, a truck, a racing car, a construction vehicle, and other large vehicles as long as it is a vehicle on which the projection display device can be installed. In addition to these, various vehicles such as a motorcycle, a train, a linear motor car, and an attraction vehicle may also be used.

[0272] The vehicle according to this embodiment can project and display a display image on a display surface provided on the vehicle (for example, the display surface 5 shown in FIG. 14) by the polarizing element 1 and the projection display device. The display surface is preferably a semi-transmissive plate such as the front glass, side glass, rear glass, or combiner of the vehicle. However, the display surface is not limited to such an example, and may be the surface of various parts, members, in-vehicle devices, etc. provided on the vehicle as long as it is the surface of an object on which the display image can be projected.

[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 such an example, and may be various image display devices such as a projector, a car navigation device, and a terminal device having an image display function that are mounted on the vehicle 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 through the windshield (display surface 5) from the outside of the vehicle. The heat of this sunlight may cause deterioration or failure of the display element 3. For this reason, for the purpose of preventing the incidence of sunlight on the display element 3, the above-described hybrid wire grid polarizing element 1 is provided in the head-up display device 100. Since this polarizing element 1 has a hybrid structure with high thermal conductivity, it is excellent in heat dissipation and heat resistance. Therefore, the polarizing element 1 can shield the sunlight incident from the outside into the head-up display device 100 and prevent it from reaching the display element 3, so that failure or breakage of the display element 3 can be prevented. Furthermore, since the polarizing element 1 is excellent in heat dissipation and heat resistance, breakage of the polarizing element 1 itself can also be prevented.

[0275] Similarly, even when the projection display device 200 shown in FIGS. 15 to 17 is installed in a vehicle, the polarizing element 1 used as the polarization beam splitter 230 can block sunlight from the outside, so that failure or breakage of other components such as the reflective liquid crystal display element 240 can be prevented. Furthermore, breakage of the polarizing element 1 itself, which is excellent in heat dissipation and heat resistance, can also be prevented.

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

[0277] Note that the vehicle is not particularly limited as long as it includes the above-described projection display device and polarizing element, and other conditions can be appropriately set and changed according to the performance required for the vehicle.

[0278] <6. Organic material constituting the grid structure (UV curable acrylic resin for imprinting)> Next, the organic material (UV curable acrylic resin for imprinting) constituting the grid structure 20 according to the present embodiment will be described.

[0279] The photocurable acrylic resin for imprinting according to this embodiment is an uncured resin composition. The photocurable acrylic resin for imprinting according to this embodiment is composed of a photopolymerizable component and a photoinitiator. The photopolymerizable component according to this embodiment is one kind of the above acrylic polymerizable compound. Further, the photoinitiator according to this embodiment is a substance for polymerizing the photopolymerizable component and corresponds to the above photocuring initiator.

[0280] <6.1. Composition of Photopolymerizable Component> Next, the composition of the photopolymerizable component of the photocurable acrylic resin for imprinting according to this embodiment will be described. The photopolymerizable component according to this embodiment at least includes resin (A) and resin (B). Further, the photopolymerizable component according to this embodiment may include resin (C) in addition to resin (A) and resin (B). Further, 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). Hereinafter, resin (A) to resin (C) will be described.

[0281] Resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group. Resin (A) is, for example, 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 phenylethyl 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 conforming to JIS Z8803. The viscosity is measured using a cone plate, for example, in the product named "Brookfield viscometer" manufactured by Eiko Seiki Co., Ltd.

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

[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, the product name "KAYARAD R-684" manufactured by Nippon Kayaku Co., Ltd. can be used.

Chemical formula

[0285] Bisacrylic acid (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene is a bifunctional acrylate monomer represented by the following chemical formula (II). As bisacrylic acid (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene, for example, the product name "KAYARAD R-604" manufactured by Nippon Kayaku Co., Ltd. can be used.

Chemical formula

[0286] 1,6 - Hexanediol diacrylate is a bifunctional acrylate monomer represented by the following chemical formula (III). As 1,6 - hexanediol diacrylate, for example, the product name "A - HD - N" manufactured by Shin - Nakamura Chemical Co., Ltd. can be used. CH2=CHCOO(CH2)6OOCCH=CH2…(III)

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

[0288] The resin (C) is, for example, an acrylate monomer having three or more functional groups. The resin (C) includes, for example, one or both of dipentaerythritol hexaacrylate and tris - (2 - acryloxyethyl) isocyanurate. As dipentaerythritol hexaacrylate, for example, the product name "KAYARAD DPHA" manufactured by Nippon Kayaku Co., Ltd. can be used. As tris - (2 - acryloxyethyl) isocyanurate, for example, the product name "A - 9300S" manufactured by Shin - Nakamura Chemical Co., Ltd. can be used.

[0289] Resin (C) has a viscosity of, for example, 1000 mPa·s or more and 12000 mPa·s or less at 25°C. When resin (C) is dipentaerythritol hexaacrylate, resin (C) has a viscosity of 5000 mPa·s or more and 10000 mPa·s or less at 25°C. When resin (C) is tris-(2-acryloxyethyl) isocyanurate, resin (C) has a viscosity of 1000 mPa·s at 50°C.

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

[0291] Also, in this embodiment, the content ratio of resin (B) with respect to the entire photopolymerizable component is 43% by mass or more, preferably 45% by mass or more. The content ratio of resin (B) with respect to the entire photopolymerizable component is 66% by mass or less, preferably 60% by mass or less. The content ratio of resin (B) with respect to the entire photopolymerizable component 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 addition, in the present embodiment, the content of the resin (C) with respect to the entire photopolymerizable component is, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more. The content of the resin (C) with respect to the entire photopolymerizable component is, for example, 30% by mass or less, preferably 20% by mass or less. The content of the resin (C) with respect to the entire photopolymerizable component is, for example, 1% by mass or more and 30% by mass or less, preferably 10% by mass or more and 20% by mass or less.

[0293] In addition, in the present embodiment, the total content of the resin (A) and the resin (B) with respect to the entire photopolymerizable component is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 85% by mass. The total content of the resin (A) and the resin (B) with respect to the entire photopolymerizable component is, for example, 99% by mass or less, preferably 90% by mass or less. The total content of the resin (A) and the resin (B) with respect to the entire photopolymerizable component is, for example, 70% by mass or more and 99% by mass or less, preferably 80% by mass or more and 90% by mass or less.

[0294] In addition, in the present embodiment, the total content of the resin (A) and the resin (C) with respect to the entire photopolymerizable component is, for example, 34% by mass or more, preferably 40% by mass or more. The total content of the resin (A) and the resin (C) with respect to the entire photopolymerizable component is, for example, 57% by mass or less, preferably 54% by mass or less. The total content of the resin (A) and the resin (C) with respect to the entire photopolymerizable component 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 addition, in the present embodiment, the total content of resin (B) and resin (C) with respect to the entire photopolymerizable component 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) with respect to the entire photopolymerizable component is, for example, 80% by mass or less, preferably 77% by mass or less. The total content of resin (B) and resin (C) with respect to the entire photopolymerizable component is, for example, 58% by mass or more and 80% by mass or less, preferably 67% by mass or more and 77% by mass or less.

[0296] In addition, in the present embodiment, the content of the resin having a viscosity of 20 mPa·s or less at 25°C with respect to the entire photopolymerizable component 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 with respect to the entire photopolymerizable component 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 with respect to the entire photopolymerizable component 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. Photoinitiator> Next, the photoinitiator according to the present embodiment will be described. The photoinitiator according to the present embodiment is, for example, an acylphosphine oxide-based photoinitiator or an alkylphenone-based photoinitiator. As the photoinitiator, for example, the product name "Irgacure819" manufactured by IGM Resins B.V. can be used.

[0298] In the photocurable acrylic resin for imprinting, when the content of the entire photopolymerizable component is 100% by mass, the content of the photoinitiator 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 the entire photopolymerizable component is 100% by mass, the content of the photoinitiator is preferably 3% by mass or less. In the photocurable acrylic resin for imprinting, when the content of the entire photopolymerizable component is 100% by mass, the content of the photoinitiator 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 the photocurable acrylic resin for imprinting> Next, the viscosity of the photocurable acrylic resin for imprinting according to the present embodiment will be described. Due to the relationship of the contents of the resin (A), resin (B), and resin (C) shown in the above 6.2., 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 the cured product of the photocurable acrylic resin for imprinting> Next, the YI (Yellow Index) value of the cured product obtained by irradiating the imprint photo-curable acrylic resin according to this embodiment with light (for example, 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 from the measurement results using, for example, the product name "UV-Visible Near-Infrared Spectrophotometer V-770" manufactured by JASCO Corporation. Specifically, in the UV-Visible Near-Infrared Spectrophotometer V-770, using a D65 light source, the transmittance of the cured product with respect to light in the wavelength range of 380 nm to 800 nm at 0° incidence is measured. Then, for the measurement results, colorimetric calculation is performed by software, and X, Y, and Z in the XYZ colorimetric system are calculated. The calculated X, Y, and Z in the XYZ colorimetric system are substituted into the following formula (3) shown in JIS K 7373:2006 to calculate the YI value. YI = 100×(1.2985X - 1.1335Z) / Y …(3)

[0301] After holding the cured product of the imprint photo-curable acrylic resin according to this embodiment at 150°C for 500 hours, the YI value of the cured product is preferably 0 or more. After holding the cured product of the imprint photo-curable acrylic resin 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 still more preferably 1.4 or less. After holding the cured product of the imprint photo-curable acrylic resin at 150°C for 500 hours, the YI value of the cured product may be 0.0 or more and 3.0 or less, preferably 0.0 or more and 2.5 or less, more preferably 0.0 or more and 2.0 or less, and still more preferably 0.0 or more and 1.4 or less.

[0302] <6.6. Average Transmittance of Cured Product of Imprint Photo-Curable Acrylic Resin> Next, the average light transmittance of the cured product of the imprint photosensitive acrylic resin according to this embodiment will be described. The average transmittance is calculated by measuring the transmittance every 1 nm in the wavelength range of 430 nm or more and 680 nm or less, and simply averaging the obtained 251 measurement data. The transmittance is measured using, for example, the product name "UV-Visible Near-Infrared Spectrophotometer V-770" manufactured by JASCO Corporation.

[0303] After holding the cured product of the imprint photosensitive acrylic resin according to this embodiment at 150 °C for 500 hours, the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 680 nm or less may be 91% or more, preferably 91.5% or more, and more preferably 92% or more. After holding the cured product of the imprint photosensitive acrylic resin at 150 °C for 500 hours, the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 680 nm or less may be 93% or less. After holding the cured product of the imprint photosensitive acrylic resin at 150 °C for 500 hours, the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 680 nm or less may be 91% or more and 93% or less, preferably 91.5% or more and 92% or less, and more preferably 92% or more and 93% or less.

[0304] Also, the difference in the average transmittance of the cured product of the imprint photo-curable acrylic resin according to this embodiment before and after holding at 150°C for 500 hours (|average transmittance before holding - average transmittance after holding|) for light in the wavelength range of 430 nm or more and 680 nm or less may be -0.2% or more. The difference in the average transmittance of the cured product of the imprint photo-curable acrylic resin according to this embodiment before and after holding at 150°C for 500 hours (|average transmittance before holding - average transmittance after holding|) for light in the wavelength range of 430 nm or more and 680 nm or less may be 0.6% or less, preferably 0.5% or less, and more preferably 0.2% or less. The difference in the average transmittance of the cured product of the imprint photo-curable acrylic resin according to this embodiment before and after holding at 150°C for 500 hours (|average transmittance before holding - average transmittance after holding|) for light in the wavelength range of 430 nm or more and 680 nm or less 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 holding the cured product of the imprint photo-curable acrylic resin according to this embodiment at 150°C for 500 hours, the average transmittance of the cured product for light in the wavelength range of 430 nm or more and 510 nm or less may be 90% or more, preferably 91% or more. After holding the cured product of the imprint photo-curable acrylic resin at 150°C for 500 hours, the average transmittance of the cured product for light in the wavelength range of 430 nm or more and 510 nm or less may be 92% or less. After holding the cured product of the imprint photo-curable acrylic resin at 150°C for 500 hours, the average transmittance of the cured product for light in the wavelength range of 430 nm or more and 510 nm or less may be 90% or more and 92% or less, preferably 91% or more and 92% or less.

[0306] In addition, the difference in the average transmittance of the cured product of the imprint photo-curable acrylic resin according to the present embodiment before and after holding at 150°C for 500 hours (|average transmittance before holding - average transmittance after holding|) for light in the wavelength range of 430 nm or more and 510 nm or less may be 0.0% or more. The difference in the average transmittance of the cured product of the imprint photo-curable acrylic resin according to the present embodiment before and after holding at 150°C for 500 hours (|average transmittance before holding - average transmittance after holding|) for light in the wavelength range of 430 nm or more and 510 nm or less may be 1.6% or less, preferably 1.1% or less, and more preferably 0.5% or less. The difference in the average transmittance of the cured product of the imprint photo-curable acrylic resin according to the present embodiment before and after holding at 150°C for 500 hours (|average transmittance before holding - average transmittance after holding|) for light in the wavelength range of 430 nm or more and 510 nm or less 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 Elastic Modulus of Cured Product of Imprint Photo-Curable Acrylic Resin> Next, the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin will be described. The storage elastic modulus is a component of the energy generated by an external force and strain that is stored inside an object. That is, the storage elastic modulus indicates the hardness of the cured product. The greater the storage elastic modulus, the harder the cured product. The storage elastic modulus can be measured, for example, using the product name "DMA7100" manufactured by Hitachi High-Tech Corporation. For example, a sheet of the cured product can be cut into a length of 20 mm and a width of 3 mm, and in the tensile mode, at a constant frequency (1 Hz), the temperature can be increased at 5°C / min, and the storage elastic modulus at 25°C to 300°C can be measured.

[0308] The storage elastic modulus of the cured product of the imprint photo-curable acrylic resin according to the present embodiment at 30°C may be 2.0×10 9 Pa or more, preferably 2.5×10 9 Pa or more, and more preferably 3.0×10 9It is above Pa. The storage elastic modulus of the cured product of the imprint photo-curable acrylic resin at 30°C may be 3.2×10 9 Pa or less. The storage elastic modulus of the cured product of the imprint photo-curable acrylic resin at 30°C may be 2.0×10 9 Pa or more and 3.2×10 9 Pa or less, preferably 2.5×10 9 Pa or more and 3.2×10 9 Pa or less, more preferably 3.0×10 9 Pa or more and 3.2×10 9 Pa or less.

[0309] The storage elastic modulus of the cured product of the imprint photo-curable acrylic resin according to this embodiment at 110°C may be 1.3×10 8 Pa or more, preferably 1.5×10 8 Pa or more, more preferably 3.0×10 8 Pa or more, still more preferably 5.0×10 8 Pa or more. The storage elastic modulus of the cured product of the imprint photo-curable acrylic resin according to this embodiment at 110°C may be 1.1×10 9 Pa or less. The storage elastic modulus of the cured product of the imprint photo-curable acrylic resin according to this embodiment at 110°C may be 1.3×10 8 Pa or more and 1.1×10 9 Pa or less, preferably 1.5×10 8 Pa or more and 1.1×10 9 Pa or less, more preferably 3.0×10 8 Pa or more and 1.1×10 9 Pa or less, still more preferably 5.0×10 8 Pa or more and 1.1×10 9 Pa or less.

[0310] The storage elastic modulus of the cured product of the imprint photo-curable acrylic resin according to this embodiment at 120°C may be 1.3×10 8 Pa or more, preferably 3.0×108 It is Pa or more, more preferably 5.0×10 8 Pa or more. The storage elastic modulus of the cured product of the imprint photosensitive acrylic resin at 120 °C may be 9.1×10 8 Pa or less. The storage elastic modulus of the cured product of the imprint photosensitive acrylic resin at 120 °C may be 1.3×10 8 Pa or more and 9.1×10 8 Pa or less, preferably 3.0×10 8 Pa or more and 9.1×10 8 Pa or less, more preferably 5.0×10 8 Pa or more and 9.1×10 8 Pa or less.

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

[0312] <6.8. Glass transition temperature Tg of the cured product of the imprint photosensitive acrylic resin> Next, the glass transition temperature Tg of the cured product of the imprint photo-curable acrylic resin will be described. The glass transition temperature Tg can be measured, for example, using the product name "DMA7100" manufactured by Hitachi High-Tech Corporation. For example, a sheet of the cured product is cut into a size of 20 mm in length and 3 mm in width, and in the tensile mode, at a constant frequency (1 Hz), the temperature is increased at a rate of 5 °C / min, and it can be measured by confirming the maximum value of the loss tangent tanδ at 25 °C to 300 °C.

[0313] The glass transition temperature Tg of the cured product of the imprint photo-curable acrylic resin according to the present 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 imprint photo-curable acrylic resin may be 181 °C or lower. The glass transition temperature Tg of the cured product of the imprint photo-curable acrylic resin 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. Manufacturing Method of Imprint Photo-Curable Acrylic Resin> Next, the manufacturing method of the imprint photo-curable acrylic resin according to the present embodiment will be described.

[0315] In the manufacturing method of the imprint photo-curable acrylic resin according to the present embodiment, after mixing a plurality of types of resins contained in the photopolymerizable component, it is preferable to mix a powder photoinitiator with the mixed resin of the plurality of types of resins. For example, when the photopolymerizable component contains resin (A) and resin (B), the manufacturing method of the imprint photo-curable acrylic resin includes mixing resin (A) and resin (B), and mixing a photoinitiator with the mixed resin of resin (A) and resin (B). Further, when the photopolymerizable component contains resin (A), resin (B), and resin (C), the manufacturing method of the imprint photo-curable acrylic resin includes mixing resin (A), resin (B), and resin (C), and mixing a photoinitiator with the mixed resin of resin (A), resin (B), and resin (C).

[0316] Also, when the photopolymerizable component contains a plurality of types of resins, in the method for producing an imprint photo-curable acrylic resin, it is preferable to produce a mixed resin by mixing in order from the resin having a lower viscosity among the plurality of types of resins contained in the photopolymerizable component. For example, when the photopolymerizable component contains resin (A), resin (B), and resin (C), the method for producing an imprint photo-curable acrylic resin includes producing a first mixed resin by mixing resin (A) and resin (B), and producing a second mixed resin by mixing resin (C) with the first mixed resin. And it is preferable to mix a photoinitiator with the second mixed resin.

[0317] In addition, for the method for producing an imprint photo-curable acrylic resin, for example, a planetary mixer may be used.

[0318] <6.10. Effects of Imprint Photo-Curable Acrylic Resin> As described above, the imprint photo-curable acrylic resin according to the present embodiment is an imprint photo-curable acrylic resin containing a photopolymerizable component. The photopolymerizable component includes resin (A) and resin (B). 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. The content of resin (A) with respect to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less, and the content of resin (B) with respect to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less.

[0319] Thus, the imprint photo-curable acrylic resin according to this embodiment contains resin (A). Resin (A) has one or both of a phenyl group and a benzyl group. Therefore, in resin (A), steric hindrance is small and reactivity is high. Thus, in the imprint photo-curable acrylic resin according to this embodiment, even when the cured product of the imprint photo-curable acrylic resin is heated, decomposition of the cured product can be suppressed by the interaction between the terminal aromatic rings. Therefore, the imprint photo-curable acrylic resin according to this embodiment can improve the heat resistance of the cured product of the imprint photo-curable acrylic resin.

[0320] Further, resin (A) is a monofunctional acrylate monomer. Therefore, resin (A) can terminate the reaction at the end of the polymer in the polymerization reaction (curing reaction) of the imprint photo-curable acrylic resin. Thus, it becomes possible to suppress deterioration from the end groups of the cured product (polymer) of the imprint photo-curable acrylic resin.

[0321] Also, the imprint photo-curable acrylic resin according to this embodiment contains resin (B). Thereby, the imprint photo-curable acrylic resin according to this embodiment can improve the heat resistance of the cured product of the imprint photo-curable acrylic resin.

[0322] Also, as described above, in the imprint photo-curable acrylic resin according to this embodiment, the content of resin (A) with respect to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less, and the content of resin (B) with respect to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less. Thereby, the imprint photo-curable acrylic resin according to this embodiment can achieve both low viscosity and improvement in the heat resistance of the cured product.

[0323] Since the photocurable acrylic resin for imprinting according to the present embodiment has a low viscosity, in the nanoimprinting step S12 (FIG. 11), when the master disk 60 is pressed against the photocurable acrylic resin for imprinting (organic material), the thickness (layer thickness) of the layer of the photocurable acrylic resin for imprinting can be made uniform. As a result, it becomes possible to make the peeling force applied when peeling the master disk 60 from the cured layer of the photocurable acrylic resin for imprinting uniform in the plane. Therefore, it is possible to avoid a situation where the cured layer of the photocurable acrylic resin for imprinting peels off from the substrate 10. For this reason, it is possible to suppress the residue of the cured layer of the photocurable acrylic resin for imprinting on the master disk 60, and the master disk 60 can be reused repeatedly. Further, since the peeling force can be made uniform in the plane, it is possible to avoid a situation where the fine concavo-convex shape transferred to the layer of the cured photocurable acrylic resin for imprinting is deformed when the master disk 60 is peeled off. For this reason, it is possible to suppress a decrease in the optical characteristics due to the fine concavo-convex shape of the cured product of the photocurable acrylic resin for imprinting. Therefore, when the grid structure 20 is manufactured from the cured product of the photocurable acrylic resin for imprinting, it is possible to suppress a decrease in the polarization characteristics of the grid structure 20.

[0324] Further, since the photocurable acrylic resin for imprinting according to the present embodiment has a low viscosity, in the nanoimprinting step S12, the followability of the photocurable acrylic resin for imprinting to the fine concavo-convex shape of the master disk 60 when the master disk 60 is pressed against the photocurable acrylic resin for imprinting can be improved. Therefore, in the nanoimprinting step S12, it becomes possible to uniformly transfer the fine concavo-convex shape of the master disk 60 to the layer of the photocurable acrylic resin for imprinting.

[0325] In addition, since the imprint photo-curable acrylic resin according to the present embodiment has a low viscosity, in the nanoimprint step S12, it is possible to suppress the incorporation of air bubbles into the imprint photo-curable acrylic resin. As a result, it is possible to avoid a situation in which a part of the fine concavo-convex shape is interrupted by air bubbles in the cured product of the imprint photo-curable acrylic resin. Therefore, when the grid structure 20 is manufactured from the cured product of the imprint photo-curable acrylic resin, disconnection of the ridge portions 22 of the grid structure 20 can be suppressed.

[0326] The cured product of the imprint photo-curable acrylic resin according to the present embodiment is excellent in heat resistance. Therefore, when an optical material (for example, the grid structure 20 of the wire grid polarizing element 1) is manufactured from the cured product of the imprint photo-curable acrylic resin, even when a heat treatment such as vapor deposition is further performed on the optical material, a decrease in the optical properties of the optical material can be further suppressed.

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

[0328] Thereby, the imprint photo-curable acrylic resin according to the present embodiment can increase the crosslinking density during curing, and can suppress a decrease in the storage elastic modulus at high temperatures of the cured product of the imprint photo-curable acrylic resin. Further, as described above, in the imprint photo-curable acrylic resin according to the present embodiment, the content of the resin (C) with respect to the entire photopolymerizable component is preferably 1% by mass or more and 30% by mass or less. Thereby, a decrease in the storage elastic modulus at high temperatures of the cured product of the imprint photo-curable acrylic resin can be further suppressed.

[0329] In addition, as described above, the resin (A) may be one or both of phenylethyl acrylate and benzyl acrylate.

[0330] As a result, the imprint photo-curable acrylic resin according to the present embodiment can further improve the heat resistance of the cured product of the imprint photo-curable acrylic resin. Further, in this case, the resin (A) has a viscosity of 9.0 mPa·s or less at 25°C. Therefore, the viscosity of the imprint photo-curable acrylic resin according to the present embodiment can be made lower.

[0331] Further, 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, bisacrylic acid (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene, and 1,6-hexanediol diacrylate.

[0332] As a result, the imprint photo-curable acrylic resin according to the present embodiment can further improve the heat resistance of the cured product of the imprint photo-curable acrylic resin.

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

[0334] As a result, the viscosity of the imprint photo-curable acrylic resin can be made lower, and the heat resistance of the imprint photo-curable acrylic resin can be further improved.

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

[0336] As a result, it is possible to further suppress the decrease in the storage elastic modulus at high temperatures of the cured product of the imprint photo-curable acrylic resin.

[0337] Further, as described above, the viscosity of the imprint photo-curable acrylic resin at 25°C may be 90 mPa·s or less.

[0338] As a result, in the nanoimprint step S12, the thickness of the layer of the imprint photo-curable acrylic resin when the master disk 60 is pressed against the imprint photo-curable acrylic resin can be made more uniform, the followability of the imprint photo-curable acrylic resin to the fine concavo-convex shape of the master disk 60 can be further improved, and the incorporation of air bubbles into the imprint photo-curable acrylic resin can be further suppressed.

[0339] Further, as described above, in the imprint photo-curable acrylic resin according to the present embodiment, the content of the resin (A) with respect to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less, and the content of the resin (B) with respect to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less, whereby the viscosity of the imprint photo-curable acrylic resin at 25°C can be 90 mPa·s or less.

[0340] For example, since the cured product of the imprint photo-curable acrylic resin according to the present embodiment is excellent in heat resistance, after the cured product of the imprint photo-curable acrylic resin is held at 150°C for 500 hours, the YI value of the cured product is 3 or less. Therefore, even when a heat treatment such as vapor deposition is further performed on the optical material by manufacturing the optical material from the cured product of the imprint photo-curable acrylic resin, yellowing of the optical material can be suppressed and transparency can be maintained.

[0341] Further, as described above, the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin at 30°C may be 2.0×10 9 Pa or more.

[0342] As a result, in the nanoimprint process S12 (FIG. 11), when peeling the master disk 60, it becomes possible to further avoid the situation where the fine concavo-convex shape transferred to the cured imprint photocurable acrylic resin layer is deformed. For this reason, it is possible to further suppress the decrease in optical characteristics due to the fine concavo-convex shape of the cured product of the imprint photocurable acrylic resin. Therefore, when manufacturing the grid structure 20 with the cured product of the imprint photocurable acrylic resin, it becomes possible to further suppress the decrease in the polarization characteristics of the grid structure 20.

[0343] Also, for example, since the cured product of the imprint photocurable acrylic resin according to the present embodiment is excellent in heat resistance, the storage elastic modulus of the cured product at 120°C may be 1.3×10 8 Pa or more. Therefore, by manufacturing an optical material with the cured product of the imprint photocurable acrylic resin, even when a heat treatment such as vapor deposition is further performed on the optical material, deformation of the optical material can be further suppressed. For this reason, it becomes possible to further suppress the decrease in the optical characteristics of the optical material.

[0344] Also, for example, since the cured product of the imprint photocurable acrylic resin according to the present embodiment is even more excellent in heat resistance, the storage elastic modulus of the cured product at 130°C may be 1.4×10 8 Pa or more. Therefore, by manufacturing an optical material with the cured product of the imprint photocurable acrylic resin, even when a heat treatment such as vapor deposition is further performed on the optical material, deformation of the optical material can be more preferably suppressed. For this reason, it becomes possible to more preferably suppress the decrease in the optical characteristics of the optical material.

[0345] Further, for example, since the cured product of the imprint photo-curable acrylic resin according to the present embodiment is more excellent in heat resistance, after holding the cured product of the imprint photo-curable acrylic resin at 150 ° C for 500 hours, the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 680 nm or less is 91% or more. Therefore, by manufacturing an optical material from the cured product of the imprint photo-curable acrylic resin, even when a heat treatment such as vapor deposition is further performed on the optical material, the average transmittance of the optical material with respect to light in the above wavelength range can be maintained higher.

[0346] Further, for example, since the cured product of the imprint photo-curable acrylic resin according to the present embodiment is more excellent in heat resistance, after holding the cured product of the imprint photo-curable acrylic resin at 120 ° C for 500 hours, the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 510 nm or less is 90% or more. Therefore, by manufacturing an optical material from the cured product of the imprint photo-curable acrylic resin, even when a heat treatment such as vapor deposition is further performed on the optical material, the average transmittance of the optical material with respect to light in the above wavelength range can be maintained higher.

[0347] Also, as described above, when manufacturing the wire grid polarizing element 1, a reflective film 30 is vapor-deposited on the grid structure 20. When the reflective film 30 is vapor-deposited, the grid structure 20 is heated. Here, if the heat resistance of the grid structure 20 is low, there is a problem that the grid structure 20 is deformed and the polarization characteristics are deteriorated during the vapor deposition of the reflective film 30.

[0348] However, the cured product of the imprint photo-curable acrylic resin according to this embodiment is more excellent in heat resistance. Therefore, by manufacturing the grid structure 20 with the cured product of the imprint photo-curable acrylic resin, even when the reflective film 30 is vapor-deposited, yellowing of the grid structure 20 and deformation of the grid structure 20 can be more suppressed, and the average transmittance of the grid structure 20 with respect to light in the wavelength range of 430 nm or more and 680 nm or less, and light in the wavelength range of 430 nm or more and 510 nm or less can be maintained higher. For this reason, it becomes possible to more suitably suppress a decrease in the polarization characteristics of the grid structure 20.

[0349] Also, as described above, in the imprint photo-curable acrylic resin according to this embodiment, the content of the resin (C) with respect to the entire photopolymerizable component is preferably 1% by mass or more and 30% by mass or less. Thereby, the heat resistance of the imprint photo-curable acrylic resin according to this embodiment can be further improved. For example, the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin at 120°C can be made 1.3×10 8 Pa or more, and the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin at 130°C can be made 1.4×10 8 Pa or more.

[0350] Also, as described above, in the method for producing an imprint photo-curable acrylic resin according to this embodiment, which includes a photopolymerizable component and a photoinitiator for polymerizing the photopolymerizable component, the photopolymerizable component includes 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, the resin (B) is a bifunctional compound, the content of the resin (A) with respect to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less, the content of the resin (B) with respect to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less, and it includes mixing the resin (A) and the resin (B), and mixing a photoinitiator with the mixed resin of the resin (A) and the resin (B).

[0351] As a result, the photopolymerizable component and the photopolymerization initiator can be suitably mixed. Therefore, the photopolymerizable component can be cured evenly (without unevenness). For this reason, it becomes possible to make the heat resistance of the cured product of the imprintable photocurable acrylic resin uniform.

[0352] Also, as described above, in the method for producing an imprintable photocurable acrylic resin containing a photopolymerizable component according to the present embodiment, the photopolymerizable component includes a resin (A), a resin (B), and a resin (C). The resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group. The resin (B) is a bifunctional compound. The resin (C) is an acrylate monomer having three or more functional groups. The content of the resin (A) with respect to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less. The content of the resin (B) with respect to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less. The content of the resin (C) with respect to the entire photopolymerizable component is 1% by mass or more and 30% by mass or less. By mixing the resin (A) and the resin (B), a first mixed resin is produced, and by mixing the resin (C) with the first mixed resin, a second mixed resin is produced.

[0353] As a result, the resin (A), the resin (B), and the resin (C) can be suitably mixed. Therefore, it becomes possible to make the viscosity of the imprintable photocurable acrylic resin uniform. Also, it becomes possible to further make the heat resistance of the cured product of the imprintable photocurable acrylic resin uniform.

[0354] <6.11. Other Components> The imprintable photocurable acrylic resin may contain other components (additives) as long as the effects shown in the above 6.10. are not impaired. Other components are, for example, antioxidants, phosphors, plasticizers, ultraviolet absorbers, defoamers, thixotropic agents, polymerization inhibitors, release agents, particles of metal oxides, and the like.

[0355] <7. Grid Inclination Structure> Next, with reference to FIGS. 18 and 19, a wire grid polarizing element 1 having a grid tilt structure according to a second embodiment of the present invention will be described. FIG. 18 is a cross-sectional view schematically showing the grid tilt structure of the wire grid polarizing element 1 according to the second embodiment. FIG. 19 is a cross-sectional view schematically showing a modified example of the grid tilt structure of the wire grid polarizing element 1 according to the second embodiment.

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

[0357] 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, similar to the polarizing element 1 (see FIG. 1 etc.) according to the first embodiment described above. The grid structure 20 is a resin structure in which a flat base portion 21 provided on the substrate 10 and a plurality of ridge portions 22 protruding from the base portion 21 are integrally formed. The ridge portion 22 has a tapered shape such that the width in the X direction becomes narrower as it moves away from the base portion 21.

[0358] Here, in the grid structure 20 according to the first embodiment described above, as shown in FIG. 1 etc., the ridge portion 22 protrudes straight upward along the normal direction (Z direction) of the surface (XY plane) of the substrate 10, and is not inclined in the width direction (X direction) of the ridge portion 22 with respect to the normal direction (Z direction) of the substrate 10. That is, the central axis of the ridge portion 22 (the axis passing through the center in the width direction (X direction) of the ridge portion 22 and extending in the height direction (Z direction) of the ridge portion 22) is substantially perpendicular to the surface (XY plane) of the substrate 10 and is substantially parallel to the normal direction (Z direction) of the substrate 10. Note that the central axis of the ridge portion 22 is an axis passing through the center in the width direction (X direction) of the ridge portion 22 and extending in the height direction (Z direction) of the ridge portion 22.

[0359] In contrast, in the grid structure 20 according to the second embodiment, as shown in FIGS. 18 and 19, at least the upper side of the rib portion 22 (the portion of the rib portion 22 that is at least covered with the reflective film 30) is inclined at a predetermined inclination angle α with respect to the normal direction (Z direction) of the substrate 10 in the width direction (X direction) of the rib portion 22. That is, the central axis 25 of the inclined portion of the rib portion 22 (the axis passing through the center in the width direction of the inclined portion of the rib portion 22 and extending in the height direction of the inclined portion of the rib portion 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 side of the rib portion 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 grid inclination structure in which at least the upper side of the rib portion 22 is inclined. Due to this grid inclination structure, directivity with respect to obliquely incident light 31 (for example, θ = -45°) incident from the inclination direction of the side where the rib portion 22 is inclined (the right side in the X direction in FIGS. 18 and 19) can be imparted to the polarization element 1. That is, due to the above-described grid inclination structure, the reflective film 30 covering the upper side of the inclined rib portion 22 can be opposed to the obliquely incident light 31 incident from the inclination direction. As a result, the P-polarized light of the obliquely incident light 31 easily passes through the gaps between the reflective films 30 of the plurality of adjacent rib portions 22, so that the transmittance Tp of the P-polarized light can be improved and the reflectance Rs of the S-polarized light of the obliquely incident light 31 can be maintained at a high value without being reduced. Therefore, directivity for enhancing the transmittance (Tp characteristic) and polarization separation characteristic (Tp × Rs characteristic) with respect to the obliquely incident light 31 incident from the inclination direction can be imparted to the polarization element 1.

[0361] For example, in the examples of FIGS. 18 and 19, the protruding ridges 22 of the grid structure 20 are inclined to the right in the X direction with respect to the normal direction (Z direction). As a result, the polarizing element 1 becomes excellent in transmittance and polarization separation characteristics with respect to obliquely incident light 31 (for example, θ = -45°) incident from a direction inclined particularly to the right among the obliquely incident lights. On the other hand, although not shown, when the protruding ridges 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 becomes excellent in transmittance and polarization separation characteristics with respect to obliquely incident light 32 (for example, θ = +45°) incident from a direction inclined particularly to the left.

[0362] As described above, the grid inclination structure according to the second embodiment can impart directivity to the polarizing element 1 so as to further enhance the transmittance (transmittance Tp) and polarization separation characteristics (Tp×Rs characteristics) with respect to the obliquely incident lights 31 and 32 incident from a specific inclination direction. Therefore, it is possible to provide a polarizing element 1 that is further excellent in transmittance (transmittance Tp) and polarization separation characteristics (Tp×Rs characteristics) with respect to the obliquely incident lights 31 and 32 incident from the specific inclination direction.

[0363] <7.1. Configuration Example of Grid Inclination Structure> Next, with reference to FIGS. 18 and 19, a configuration example of the grid inclination structure according to the second embodiment will be described.

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

[0365] More specifically, in the grid inclination structure shown in FIG. 18, the rib portion 22 is bent to the right side in the width direction (X direction) of the rib portion 22 at a position 27 in the middle of the height direction (Z direction) of the rib portion 22. Therefore, the upper portion 22c (the portion above the bending position 27) of the rib portion 22 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, the lower portion 22d (the portion below the bending position 27) of the rib portion 22 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 (the inclined portion) of the rib portion 22 is bent at an inclination angle α to the right side in the X direction with respect to the central axis 26 of the lower portion 22d (the non-inclined portion) of the rib portion 22. The central axis 25 is an axis that passes through the center in the width direction of the inclined upper portion 22c of the rib portion 22 and extends in the height direction of the upper portion 22c. The central axis 26 is an axis that passes through the center in the width direction (X direction) of the non-inclined lower portion 22d of the rib portion 22 and extends in the height direction (Z direction) of the lower portion 22d.

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

[0368] As described above, in the grid tilt structure shown in FIG. 18, the rib portion 22 bends in the X direction in the middle of the Z direction, so that only the upper portion 22 c of the rib portion 22 is partially inclined. As a result, oblique incident light can be preferably incident on the lower open portion (resin portion not covered by the reflective film 30) of the side surface 22 b of the rib portion 22 of the grid structure 20. Therefore, the bent grid tilt structure shown in FIG. 18 is superior in the transmittance of oblique incident light and the polarization separation characteristics compared to the overall grid tilt structure shown in FIG. 19. Further, the bent grid tilt structure shown in FIG. 18 can expand the preferable range of the tilt angle α compared to the overall grid tilt structure shown in FIG. 19.

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

[0370] For this reason, the central axis 25 of the entire rib portion 22 is inclined at an inclination angle α to the right side 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 rib portion 22 is also inclined at an inclination angle α to the right side in the X direction. The central axis 25 shown in FIG. 19 is an axis that passes through the center in the width direction of the inclined rib portion 22 and extends in the height direction of the inclined rib portion 22.

[0371] Thus, in the grid tilt structure shown in FIG. 19, the entire rib portion 22 is inclined. The grid tilt structure in which the entire rib portion 22 shown in FIG. 19 is inclined has a relatively simple shape compared to the bent grid tilt structure shown in FIG. 18 described above. Therefore, when molding the grid structure 20 using a transfer technique such as imprinting, the releasability and the like are improved, so that the grid tilt structure can be molded relatively easily and with high precision.

[0372] <7.2. Preferable Range of Tilt Angle α> Next, the preferable range of the inclination angle α of the rib portion 22 of the grid inclination structure according to the second embodiment will be described.

[0373] (1) 0° < α ≤ 15° The inclination angle α of the rib portion 22 is preferably more than 0° and less than or equal to 15°. When the inclination angle α of the rib portion 22 exceeds 15°, since the inclination of the rib portion 22 is too large, the transmittance Tp may decrease compared to the case where the rib portion 22 is not inclined. On the other hand, if the inclination angle α of the rib portion 22 is 15° or less, the rib portion 22 can be inclined at an appropriate inclination angle α in accordance with the obliquely incident light incident from the side where the rib portion 22 is inclined. Therefore, the transmittance Tp can be increased compared to the case where the rib portion 22 is not inclined, and the polarization separation characteristic (Tp × Rs characteristic) can be improved.

[0374] For example, in the grid inclination structure shown in FIG. 18, when the obliquely incident light 31 is incident at an incident angle θ = -45° from the side where the rib portion 22 is inclined, if the inclination angle α is more than 0° and less than or equal to 15°, the grid structure 20 can be given a 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, so that Tp × Rs can be increased to a value equal to or higher than the reference value (for example, 76% or more).

[0375] Note that the reference value is the reference value of Tp × Rs measured using the grid structure 20 in which the rib portion 22 according to the first embodiment is not inclined, and is, for example, 76%. By adopting the grid inclination structure according to the second embodiment, if the value of Tp × Rs can be increased to a value equal to or higher than the reference value, it can be said that there is an effect of improving the polarization separation characteristic (Tp × Rs) with respect to the obliquely incident light incident from a specific inclination direction.

[0376] Also, in the grid tilt structure shown in Fig. 19, when the obliquely incident light 31 is incident at an incident angle θ = -45° from the side where the convex strip portion 22 is tilted, if the tilt angle α is more than 0° and 10° or less, 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. Thus, Tp×Rs can be increased to a value equal to or higher than the reference value (for example, 76% or more).

[0377] (2) 5° ≤ α ≤ 10° Furthermore, it is more preferable that the tilt angle α of the convex strip portion 22 is 5° or more and 10° or less. Thereby, in accordance with the obliquely incident light 31 incident from the side where the convex strip portion 22 is tilted, the convex strip portion 22 can be tilted at a more appropriate tilt angle α. Therefore, the transmittance Tp can be further increased, and the polarization separation characteristics (Tp×Rs characteristics) can be further improved.

[0378] For example, in the grid tilt structure shown in Fig. 18, when the obliquely incident light 31 (θ = -45°) incident from the side where the convex strip portion 22 is tilted is incident, if the tilt angle α is 5° or more and 10° or less, the grid structure 20 can be given directivity 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. Thus, Tp×Rs can be further increased to, for example, 77.3% or more.

[0379] Also, in the grid tilt structure shown in Fig. 19, when the above obliquely incident light 31 (θ = -45°) is incident, if the tilt angle α is 5° or more and 10° or less, the grid structure 20 can be given directivity 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. Thus, Tp×Rs can be further increased to, for example, 76.7% or more.

[0380] <7.3. Preferred range of the coverage ratio Rc> Next, in the grid inclination structure according to the second embodiment, the preferable range of the coverage rate Rc when the side surface 22b of the convex rib portion 22 is covered with the reflective film 30 will be described.

[0381] <7.3.1. Coverage rate Rc of both side surfaces> As shown in FIGS. 18 and 19, in the grid structure 20 having the grid inclination structure according to the second embodiment, the reflective film 30 (functional film) covers the tip 22a and the upper sides of both side surfaces 22b1 and 22b2 (hereinafter, may be collectively referred to as "side surface 22b") of the inclined convex rib portion 22. And it is preferable that the coverage rates Rc (hereinafter, referred to as "coverage rates Rc1 and Rc2", respectively) of both side surfaces 22b1 and 22b2 of the convex rib portion 22 by the reflective film 30 are 30% or more and 70% or less.

[0382] In this way, since the reflective film 30 covers both side surfaces 22b1 and 22b2 of the inclined convex rib portion 22 and the coverage rates Rc1 and Rc2 are 30% or more and 70% or less, the grid inclination structure having the inclined convex rib portion 22 can correspond to both "obliquely incident light 31 in the - direction" and "obliquely incident light 32 in the + direction". Therefore, regardless of the direction from which the obliquely incident light is incident, a certain degree of good transmittance (transmittance Tp) and polarization separation characteristics (Tp×Rs characteristics) can be realized.

[0383] In this specification, the "obliquely incident light in the - direction" is obliquely incident light incident from the side where the convex rib portion 22 is inclined with respect to the surface (XY plane) of the polarizing element 1. The incident angle θ of the "obliquely incident light 31 in the - direction" is a negative value less than 0° (θ < 0°). That is, when the incident angle θ is a negative value (for example, θ = -45°), it means that the obliquely incident light is obliquely incident from the direction of the side where the convex rib portion 22 is inclined (the positive direction of the X axis) toward the negative direction of the X axis.

[0384] On the one hand, the "obliquely incident light in the + direction" is the obliquely incident light that is incident from the side opposite to the side where the convex strip portion 22 is inclined. The incident angle θ of the "obliquely incident light in the + direction" is a positive value greater than 0° (θ > 0°). That is, when the incident angle θ is a positive value (for example, θ = +45°), it means that the obliquely incident light is obliquely incident from the direction opposite to the side where the convex strip portion 22 is inclined (the negative direction of the X-axis) toward the side where the convex strip portion 22 is inclined (the positive direction of the X-axis).

[0385] For example, in the grid inclination structure shown in FIGS. 18 and 19, the convex strip portion 22 is inclined to the right side in the X direction (the positive direction of the X-axis) with respect to the Z direction. Therefore, the "obliquely incident light in the - direction" is the obliquely incident light 31 that is incident at a negative incident angle θ (for example, θ = -45°) from the right side in the X direction (the positive direction of the X-axis) toward the left side in the X direction (the negative direction of the X-axis). Also, the "obliquely incident light in the + direction" is the obliquely incident light 32 that is incident at a positive incident angle θ (for example, θ = +45°) from the left side in the X direction (the negative direction of the X-axis) toward the right side in the X direction (the positive direction of the X-axis).

[0386] Also, the range of the incident angle θ of the obliquely incident light varies depending on the specifications and uses of the polarizing element 1. For example, it is in the range of a predetermined angular width (for example, ±15°, ±10°) centered on the centrally obliquely incident light at 45°. More specifically, when the incident angle of the centrally obliquely incident light is 45° and the angular width is ±15°, the range of the incident angle θ of the obliquely incident light is, for example, +45° ± 15° (that is, +30° to 60°), -45° ± 15° (that is, -60° to -30°). Also, the incident angle of the centrally obliquely incident light may be various angles such as 30° and 55° in addition to the above example of 45°. Furthermore, the predetermined angular width may also be various angular widths such as ±5°, ±20°, and ±25° in addition to the above examples of ±15° and ±10°.

[0387] <7.3.2. The First Side and the Second Side of the Convex Strip Portion> The first side surface of the rib portion 22 is the side surface on the inclined side of the rib portion 22 among the both side surfaces 22b, 22b of the rib portion 22. On the other hand, the second side surface of the rib portion 22 is the side surface on the side opposite to the inclined side of the rib portion 22 among the both side surfaces 22b, 22b of the rib portion 22.

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

[0389] The coverage rate Rc1 of the first side surface 22b1 of the rib portion 22 is represented by the following formula (11). Rc1 [%] = (Hx1 / H) × 100 ··· (11) H: Height of the rib portion 22 in the Z direction [nm] Hx1: Height of the portion covered by the reflective film 30 in the Z direction of the first side surface 22b1 of the rib portion 22 [nm]

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

[0391] <7.3.3. Coverage rate Rc1 of the first side surface of the rib portion> (1) Oblique incident light in one direction (35% ≤ Rc1 ≤ 50%) When obliquely 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 "obliquely incident light in the - direction" is incident at a negative incident angle θ), the coverage rate Rc1 of the first side surface 22b1 of the convex rib portion 22 is preferably 35% or more and 50% or less.

[0392] Thereby, when "obliquely incident light in the - direction" is incident, the coverage rate Rc1 of the first side surface 22b1 can be adjusted to an appropriate range according to the negative incident angle θ (for example, θ = -45°). Therefore, while maintaining the reflectance Rs at a high value of 90% or more, the transmittance Tp can be increased to 84% or more, for example. Thus, Tp × Rs can be increased to a reference value or more (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 where the convex rib portion 22 is inclined (that is, when "obliquely incident light in the + direction" is incident at a positive incident angle θ), the coverage rate Rc1 of the first side surface 22b1 of the convex rib portion 22 is preferably 40% or more and 53% or less.

[0394] Thereby, when "obliquely incident light in the + direction" is incident, the coverage rate Rc1 of the first side surface 22b1 can be adjusted to an appropriate range according to the positive incident angle θ (for example, θ = +45°). Therefore, while maintaining the reflectance Rs at a high value of 90% or more, the transmittance Tp can be increased to 84% or more, for example. Thus, Tp × Rs can be increased to a reference value or more (for example, 76% or more) (see Fig. 23).

[0395] <7.3.4. Coverage rate Rc2 of the second side surface of the convex rib portion> (1) Obliquely incident light in the - direction (35% ≤ Rc2 ≤ 55%) When obliquely 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 "obliquely incident light in the - direction" is incident at a negative incident angle θ), the coverage rate Rc2 of the second side surface 22b2 of the convex rib portion 22 is preferably 35% or more and 55% or less.

[0396] Thus, when "-direction obliquely incident light" is incident, the coverage ratio Rc2 of the second side surface 22b2 can be adjusted to an appropriate range in accordance with the negative incident angle θ (for example, θ = -45°). 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, so that Tp × Rs can be increased to a value equal to or higher than a reference value (for example, 76% or more) (see FIG. 24).

[0397] (2) +-direction obliquely incident light (35% ≤ Rc2 ≤ 45%) When obliquely incident light 32 is incident on the surface of the polarization element 1 from the side opposite to the side where the convex stripe portion 22 is inclined (that is, when "+-direction obliquely incident light" is incident at a positive incident angle θ), the coverage ratio Rc2 of the second side surface 22b2 of the convex stripe portion 22 is preferably 35% or more and 45% or less.

[0398]

Example

[0399] Next, an example of the present invention will be described. However, the examples described below are specific examples illustrated for explaining the configuration, effects, etc. of the polarization element 1 according to the above-described present embodiment, and the present invention is not limited to the following examples.

[0400] <1. Verification results of grid tilt structure>​As an example of the present invention, a model of the wire grid polarizing element 1 having the grid tilt structure according to the second embodiment described above was fabricated, and various characteristics thereof were simulated to evaluate the wire grid polarizing element 1 (tilt angle α>0°) according to the example. Further, in order to compare with the wire grid polarizing element 1 (tilt angle α>0°) having the grid tilt structure according to the example of the present invention, a model of the wire grid polarizing element 1 (tilt angle α = 0°) according to the comparative example having no such grid tilt structure was also created and similarly simulated and evaluated. In the following, for convenience of explanation, in both the example and the comparative example, reference numerals representing the components of the polarizing element 1 (substrate 10, grid structure 20, base portion 21, rib portion 22, reflective film 30, etc.) and symbols representing various dimensions of these components are given the same reference numerals and symbols.

[0401] Note that symbols representing various dimensions and the like of the polarizing element 1 used in the following description are as follows. P: Pitch of the rib portion 22 W T : Width of the top of the rib portion 22 (width of the rib top) W M : Width at the central position in the height direction of the rib portion 22 (width at the rib center) W B : Width of the bottom of the rib portion 22 (width at the grid bottom) W MAX : Maximum width of the reflective film 30 covering the rib portion 22 (width at the grid maximum) H: Height of the rib portion 22 Hx: Height of the portion of the side surface 22b of the rib portion 22 covered by the reflective film 30 Hx1: Height of the portion of the first side surface 22b1 of the rib portion 22 covered by the reflective film 30 Hx2: Height of the portion of the second side surface 22b2 of the rib portion 22 covered by the reflective film 30 Dt: Thickness of the reflective film 30 covering the tip 22a of the rib portion 22 (tip thickness of the reflective film 30) Ds: Thickness of the reflective film 30 covering the side surface 22b of the rib portion 22 (side thickness of the reflective film 30) Rc: Coverage rate of the side surface 22b of the rib portion 22 by the reflective film 30 Rc1: Coverage rate of the first side surface 22b1 of the rib portion 22 by the reflective film 30 Rc2: Coverage rate of the second side surface 22b2 of the rib portion 22 by the reflective film 30 Rr: Opening rate of the side surface 22b of the rib portion 22 by the reflective film 30 Rr1: Opening rate of the first side surface 22b1 of the rib portion 22 by the reflective film 30 Rr2: Opening rate of the second side surface 22b2 of the rib portion 22 by the reflective film 30 θ: Incident angle of incident light λ: Wavelength of incident light α: Inclination angle of the rib portion 22

[0402] (Example 40) First, referring to FIGS. 20 and 21, Example 40 of the present invention will be described.

[0403] As shown in FIG. 20, a model of the 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 rib portions 22 protruding from the base portion 21 in a grid pattern. The cross-sectional shape of the rib portion 22 is a vertically long trapezoid, and it has a tapered shape that becomes thinner toward the tip 22a of the rib portion 22.

[0404] The reflective film 30 covering the rib portion 22 of Example 40 is an Al film. The reflective film 30 is formed so as to cover the tip 22a of the rib 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 rib portion 22 and the base portion 21. The coverage rates Rc1 and Rc2 of both side surfaces 22b1 and 22b2 of the rib portion 22 by the reflective film 30 are 45%. Thus, the reflective film 30 of Example 40 roundly covers and wraps the top of the rib portion 22 (the tip 22a and the upper sides of both side surfaces 22b1 and 22b2). The surface of the reflective film 30 has a substantially elliptical shape with a bulge outward, and bulges in the width direction of the rib portion 22.

[0405] As a result, the grid (the structure combining the convex strip portion 22 and the reflective film 30) according to Example 40 has the above-described special tree shape. The maximum width W of the grid with the special tree shape MAX (the width of the grid at the portion where the reflective film 30 bulges the most) is equal to or greater than the width W of the bottom of the convex strip portion 22 B (the width of the convex strip portion 22 at a height position 20% above the bottom of the convex strip portion 22).

[0406] In Example 40, in order to provide a grid inclination structure, the upper portion 22c of the convex strip portion 22 was inclined at an inclination angle α to one side in the width direction of the convex strip portion 22 (the right side in FIG. 20(a)). The inclined upper portion 22c was the upper 50% portion in the height direction of the convex strip portion 22. The inclination angles α in Example 40 were 5°, 10°, and 15°.

[0407] On the other hand, in the model of the polarizing element 1 according to Comparative Example 40, the convex strip portion 22 was not inclined and a grid inclination structure was not provided. That is, in Comparative Example 40, the inclination angle α = 0°, and the convex strip portion 22 was made to extend straight upward in the normal direction (Z direction) of the surface of the substrate 10.

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

[0409] The dimensions and shapes of each part of the models of the polarizing element 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 : 65 nm H: 225 nm Hx = Hx1 = Hx2: 101 nm Dt: 38 nm Ds: 17.5 nm (maximum value) Rc = Rc1 = Rc2: 45% Rr = Rr1 = Rr2: 55% θ: -45°, +45° λ: 430~680 nm α: 5°, 10°, 15° (Example 40) α: 0° (Comparative Example 40) α: 20°, 25°, 30°, 35°, 40°, 45° (Comparative Example 41)

[0410] A simulation was performed on the models of the polarization element 1 according to Example 40 and Comparative Examples 40 and 41 fabricated 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 as a polarization beam splitter (PBS) were calculated respectively. At this time, 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 respectively when "oblique incident light in the - direction (θ = -45°)" was incident and when "oblique incident light in the + direction (θ = +45°)" was incident. Note that as the values of Tp, Ts, Rp, and Rs, the wavelength λ of the oblique incident light was changed in the range of 430~680 nm, and the average values of a plurality of 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, Tp×Rs characteristics according to Example 40 and Comparative Examples 40 and 41 obtained as described above and the tilt angle α are shown in the graphs of FIGS. 20(b) to (d) and the graphs of FIGS. 21(b) to (d). Note that although the scales of the tilt angle α on the horizontal axes of the graphs of FIGS. 20(b) to (d) and the graphs of FIGS. 21(b) to (d) are different, they show the same Tp characteristics, Rs characteristics, and Tp×Rs characteristics.

[0412] As shown in Fig. 20(a), in the model of the polarizing element 1 according to Example 40, the reflective film 30 covers the top of the convex strip portion 22 and opens the bottom of the convex strip portion 22, and the coverage rate Rc is 45%. Therefore, the grid (the structure combining the convex strip portion 22 and the reflective film 30) according to Example 40 has the above-mentioned special tree shape. Further, the grid according to Example 40 has a bent grid inclination structure in which the upper portion 22c of the convex strip portion 22 is bent and inclined to the right, and the inclination angle α of the upper portion 22c of the convex strip portion 22 is adjusted to an appropriate range greater than 0° and less than or equal to 15°.

[0413] As shown in Figs. 20 and 21, in Example 40 (α = 5° to 15°), since the inclination angle α of the bent grid inclination structure is within an appropriate range, compared with Comparative Example 40 (α = 0°) and Comparative Example 41 (α = 20° to 45°), it is excellent in transmittance (Tp characteristic) and polarization separation characteristic (Tp×Rs characteristic) for obliquely incident light from a specific inclination direction (for example, obliquely incident light in the - direction (θ = -45°) and obliquely incident light in the + direction (θ = +45°)).

[0414] Specifically, first, comparing the reflectance Rs, as shown in Figs. 20(c) and 21(c), in the range where the inclination angle α is 0° to 45°, regardless of the magnitude of α, Rs maintains a high value of 90% or more. Therefore, when the convex strip portion 22 is inclined as in Example 40 (α = 5° to 15°), it can be seen that, similar to the case where the convex strip portion 22 is not inclined as in Comparative Example 40 (α = 0°), a high Rs of 90% or more can be ensured, and the excellent reflectivity (Rs characteristic) by the reflective film 30 can be exhibited.

[0415] Next, when comparing the transmittance Tp, as shown in Fig. 20(b), the Tp of Comparative Example 40 (α = 0°) which is the reference is about 84%. Also, as shown in Fig. 21(b), in Comparative Example 41 (α = 20° to 45°), Tp is 82% or less, which is lower than that of Comparative Example 40 (α = 0°) which is the reference. And in Comparative Example 41, as α increases in the range of 20° or more, Tp decreases, and when α = 45°, Tp has decreased to 60% or less. Therefore, in the case of the bent grid tilt structure shown in Fig. 20(a), when α is 20° or more as in Comparative Example 41, since the tilt angle α of the rib portion 22 is too large, Tp becomes small, and it can be seen that this is not preferable.

[0416] On the other hand, the Tp of Example 40 (α = 5° to 15°) is 84.3% or more, and is higher than that of Comparative Example 40 (α = 0°) which is the reference for both the + - direction obliquely incident light (θ = + 45°) and the - direction obliquely incident light (θ = - 45°). In particular, when α = 5° and 10° in Example 40, it has excellent directivity with respect to the - direction obliquely incident light (θ = - 45°), and 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 if α is in an appropriate range of more than 0° and 15° or less as in Example 40, the transmittance (Tp characteristic) with respect to obliquely incident light from a specific tilt direction (θ = - 45°, + 45°) can be improved. In particular, if α is in a preferable range of 5° or more and 10° or less, it can be seen that it has very excellent transmittance (Tp characteristic) with respect to the - direction obliquely incident light (θ = - 45°).

[0418] Next, compare Tp×Rs obtained by multiplying the above Rs and Tp. As shown in Fig. 20(d), Tp×Rs of Comparative Example 40 (α = 0°) as the reference is about 76%. Also, as shown in Fig. 21(d), in Comparative Example 41 (α = 20° to 45°), Tp×Rs is 75% or less, which is lower than that of Comparative Example 40 (α = 0°) as the reference. And in Comparative Example 41, as α increases in the range of 20° or more, Tp×Rs decreases, and when α = 45°, Tp×Rs has decreased to 55% or less. Therefore, in the case of the bent grid tilt structure shown in Fig. 20(a), when α is 20° or more as in Comparative Example 41, since α is too large, Tp×Rs becomes small, which is found to be unfavorable.

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

[0420] Therefore, in the case of the bent grid tilt structure shown in Fig. 20(a), it can be seen that if α is in an appropriate range of more than 0° and 15° or less as in Example 40, the polarization separation characteristics (Tp×Rs characteristics) for obliquely incident light from a specific tilt direction (θ = - 45°, + 45°) can be improved. In particular, if α is in a preferable range of 5° or more and 10° or less, it can be seen that it has very excellent polarization separation characteristics (Tp×Rs characteristics) with respect to the - direction obliquely incident light (θ = - 45°).

[0421] As described above, regarding 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 between 5° and 10°, Tp×Rs characteristics with directivity with respect to obliquely incident light in the - direction (θ = -45°) can be obtained. Therefore, when the polarizing element 1 according to Example 40 is used as a polarizing beam splitter, it can be seen that the transmittance of P-polarized light (transmittance Tp) and the polarization separation characteristics (Tp×Rs characteristics) are significantly superior with respect to obliquely incident light incident from a specific direction. Thus, it can be said that the polarization separation characteristics required for a polarizing beam splitter can be sufficiently satisfied with respect to obliquely incident light incident from the specific direction. Therefore, when an image is projected using the polarizing element 1 according to Example 40 as a polarizing beam splitter, from the perspective of an observer, the brightness balance of the displayed image is good, and the video state is also good.

[0422] As described above, in Example 40, in the bent grid tilt structure shown in Fig. 20(a), the tilt angle α of the ridge portion 22 is adjusted to an appropriate angle greater than 0° and less than or equal to 15°. As a result, in Example 40, while maintaining Rs at a high value of 90% or more, Tp can be increased to more than 84%, so Tp×Rs can be increased to more than 76%, which is the reference value. Therefore, according to Example 40, it can be seen that good transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) superior to those of Comparative Example 40 as a reference can be obtained for both +-direction obliquely incident light (θ = +45°) and -direction obliquely incident light (θ = -45°).

[0423] In particular, with respect to the -direction obliquely incident light (θ = -45°), it can be seen that by tilting the upper portion 22c of the ridge portion 22 at a tilt angle α of 5° or more and 10° or less, the transmittance (Tp characteristics) and the polarization separation characteristics (Tp×Rs characteristics) can be significantly improved. Therefore, it can be said that a polarizing element 1 having directivity with respect to the -direction obliquely incident light (θ = -45°) and excellent in transmittance and polarization separation characteristics can be provided.

[0424] (Example 42) Next, with reference to Fig. 22, Example 42 of the present invention will be described.

[0425] As shown in Fig. 22, a model of the polarizing element 1 according to Example 42 was fabricated. In Example 42, except for the way of inclining the rib portion 22, a grid having a special tree shape (a structure combining the rib portion 22 and the reflective film 30) was fabricated in the same manner as in Example 40 described above.

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

[0427] On the other hand, in the model of the polarizing element 1 according to Comparative Example 42, the rib portion 22 was not inclined and a grid inclination structure was not provided. That is, in Comparative Example 42, the inclination angle α = 0°, and the rib portion 22 was made to extend straight upward in the normal direction (Z direction) of the surface of the substrate 10.

[0428] Also, as Comparative Example 43, a model in which the entire rib portion 22 was inclined at a large inclination angle α exceeding 10° to one side in the width direction of the rib portion 22 (the right side in Fig. 22(a)) was also fabricated. The inclination angles α in Comparative Example 43 were 15° and 30°.

[0429] The dimensions and shapes of each part of the models of the polarizing element 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 : 65 nm H: 225 nm Hx = Hx1 = Hx2: 101 nm Dt: 38 nm Ds: 17.5 nm (maximum value) Rc = Rc1 = Rc2: 45% Rr = Rr1 = Rr2: 55% θ: -45°, +45° λ: 430 - 680 nm 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 polarization element 1 according to Example 42 and Comparative Examples 42 and 43 fabricated as described above, and Tp, Ts, Rp, Rs, and Tp×Rs were calculated respectively. At this time, 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 respectively when "oblique incident light in the - direction (θ = -45°)" was incident and when "oblique incident light in the + direction (θ = +45°)" was incident. Note that as the values of Tp, Ts, Rp, and Rs, the wavelength λ of the oblique incident light was changed in the range of 430 to 680 nm, and the average values of a plurality of Tp, Ts, Rp, and Rs values calculated for the oblique incident light of each wavelength λ were used.

[0431] The relationships between the Tp characteristics, Rs characteristics, Tp×Rs characteristics according to Example 42 and Comparative Examples 42 and 43 obtained as described above and the tilt angle α are shown in the graphs of FIGS. 22(b) to (d).

[0432] As shown in FIG. 22(a), in the model of the polarization element 1 according to Example 42, the reflective film 30 covers the top of the convex strip portion 22 and the bottom of the convex strip portion 22 is open, and the coverage rate Rc is 45%. Therefore, the grid (the structure combining the convex strip portion 22 and the reflective film 30) according to Example 42 has the above-described special tree shape. Further, the grid according to Example 42 has an overall grid tilt structure in which the entire convex strip portion 22 is tilted to the right, and the overall tilt angle α of the convex strip portion 22 is adjusted to an appropriate range greater than 0° and less than or equal to 15°.

[0433] As shown in FIG. 22, in Example 42 (α = 5° to 10°), since the tilt angle α of the overall grid tilt structure is within an appropriate range, compared with Comparative Example 42 (α = 0°) and Comparative Example 43 (α = 30°), it is excellent in transmissivity (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) for oblique incident light from a specific tilt direction (for example, oblique incident light in the - direction (θ = -45°) and oblique incident light in the + direction (θ = +45°)).

[0434] Specifically, first, comparing the reflectance Rs, as shown in Fig. 22(c), in the range where the tilt angle α is from 0° to 30°, Rs maintains a high value of 90% or more regardless of the magnitude of α. Therefore, when the rib portion 22 is tilted as in Example 42 (α = 5° to 15°), it can be seen that, similar to the case where the rib portion 22 is not tilted as in Comparative Example 42 (α = 0°), a high Rs of 90% or more can be ensured, and excellent reflectivity (Rs characteristics) by the reflective film 30 can be exhibited.

[0435] Next, comparing the transmittance Tp, as shown in Fig. 22(b), the Tp of Comparative Example 42 (α = 0°) which is the reference is about 84%. Also, in Comparative Examples 43 (α = 15°, 30°), Tp is 83% or less, which is significantly lower than that of Comparative Example 42 (α = 0°) which is the reference. And in Comparative Example 43, as α increases in the range of 15° or more, Tp decreases. Therefore, in the case of the overall grid tilt structure shown in Fig. 22(a), when α is 15° or more as in Comparative Example 43, since the tilt angle α of the rib portion 22 is too large, Tp becomes small, which is not preferable.

[0436] On the other hand, the Tp of Example 42 (α = 5°, 10°) is 84% or more, and is equal to or higher than that of Comparative Example 42 (α = 0°) which is the reference for both the + - direction obliquely incident light (θ = + 45°) and the - direction obliquely incident light (θ = - 45°). In particular, in the case of the - direction obliquely incident light (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°). Also, when α = 5° in Example 42, for both the + - direction obliquely incident light (θ = + 45°) and the - direction obliquely incident light (θ = - 45°), Tp is 84.5% or more, which is significantly higher than that of Comparative Example 42 (α = 0°).

[0437] Therefore, in the case of the overall grid tilt structure shown in Fig. 22(a), as in Example 42, if α is within an appropriate range greater than 0° and less than or equal to 10°, it can be seen that the transmittance (Tp characteristic) for obliquely incident light from a specific tilt direction (θ = -45°, +45°) can be improved. In particular, it can be seen that it has very excellent transmittance (Tp characteristic) for obliquely incident light in the - direction (θ = -45°).

[0438] Next, a comparison is made for Tp×Rs obtained by multiplying the above Rs and Tp. As shown in Fig. 22(d), the Tp×Rs of Comparative Example 42 (α = 0°) as a reference is about 76%. Also, in Comparative Examples 43 (α = 15°, 30°), Tp×Rs is 75.2% or less, which is lower than that of Comparative Example 42 (α = 0°) as a reference. Therefore, in the case of the overall grid tilt structure shown in Fig. 22(a), when α is 15° or more as in Comparative Example 43, since α is too large, Tp×Rs becomes small, which is not preferable.

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

[0440] Therefore, in the case of the overall grid tilt structure shown in Fig. 22(a), as in Example 42, if α is within an appropriate range greater than 0° and less than or equal to 10°, it can be seen that the polarization separation characteristic (Tp×Rs characteristic) for obliquely incident light from a specific tilt direction (θ = -45°, +45°) can be improved. In particular, if α is within a preferable range of 5° or more and 10° or less, it can be seen that it has very excellent polarization separation characteristic (Tp×Rs characteristic) for obliquely incident light in the - direction (θ = -45°).

[0441] As described above, in Example 42, in the overall grid tilt structure shown in Fig. 22(a), the tilt angle α of the rib portion 22 is adjusted to an appropriate angle greater than 0° and less than or equal to 10°. As a result, in Example 42, while maintaining Rs at a high value of 90% or more, Tp can be increased to 84% or more, so that Tp×Rs can be increased to more than 76%, which is the reference value. Therefore, according to Example 42, it can be seen that good transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) superior to those of Comparative Example 42, which is the reference, can be obtained for both the +-direction obliquely incident light (θ = +45°) and the -direction obliquely incident light (θ = -45°).

[0442] In particular, for the -direction obliquely incident light (θ = -45°), it can be seen that the transmittance (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) can be significantly improved by tilting the entire rib portion 22 at a tilt angle α of 5° or more and 10° or less. Therefore, it can be said that a polarizing element 1 having directivity with respect to the -direction obliquely incident light (θ = -45°) and excellent in transmittance and polarization separation characteristics can be provided.

[0443] (Example 43) Next, with reference to Fig. 23, Example 43 of the present invention will be described.

[0444] As shown in Fig. 23, a model of the polarizing element 1 according to Example 43 was fabricated. In Example 43, a grid (a structure combining the rib portion 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 rate Rc1 of the first side surface 22b1 of the rib portion 22 was changed. In Example 43, in order to provide a grid tilt structure, the upper portion 22c of the rib portion 22 (the upper 50% portion of the rib portion 22) was tilted at a tilt angle α to one side in the width direction of the rib portion 22 (the right side in Fig. 23(a)). The tilt angle α in Example 43 was fixed at 10°.

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

[0446] The dimensions and shapes of the respective 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 values) Hx2: 101 nm (fixed value) Dt : 38 nm Ds : 17.5 nm (maximum value) Rc1 : 35%, 40%, 45%, 50%, 55% (variable values) Rr1 : 65%, 60%, 55%, 50%, 45% (variable values) 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 fabricated as described above, and Tp, Ts, Rp, Rs, and Tp×Rs were calculated respectively. At this time, the values of Tp, Ts, Rp, and Rs were calculated respectively when "oblique incident light in the - direction (θ = -45°)" was incident and when "oblique incident light in the + direction (θ = +45°)" was incident. Note that as the values of Tp, Ts, Rp, and Rs, the wavelength λ of the oblique incident light was varied in the range of 430 to 680 nm, and the average values of a plurality of Tp, Ts, Rp, and Rs values calculated for the oblique incident light of each wavelength λ were used. Also, by dividing Tp by Ts, the contrast (CR) of the transmitted light was also calculated (CR = Tp / Ts).

[0448] The relationships between the Tp characteristics, Rs characteristics, Tp×Rs characteristics, contrast CR according to Example 43 obtained as described above, and the coverage rate Rc1 of the first side surface 22b1 are shown in the graphs of FIGS. 23(b) to (e).

[0449] As shown in FIG. 23(c), the reflectance Rs of Example 43 maintains a high value of 90% or more regardless of the magnitude of the coverage rate Rc1 (35 to 55%) in both the case of "oblique incident light in the - direction (θ = -45°)" and the case of "oblique incident light in the + direction (θ = +45°)". Therefore, it can be seen that regardless of Rc1, a high Rs of 90% or more can be ensured, and excellent reflectivity (Rs characteristics) by the reflective film 30 can be exhibited.

[0450] On the other hand, as shown in FIGS. 23(b) and 23(d), for the Tp characteristics and Tp×Rs characteristics, the behaviors of the Tp characteristics and Tp×Rs characteristics according to the coverage rate Rc1 are different depending on whether the incident direction of the oblique incident light is " - direction (θ = -45°)" or " + direction (θ = +45°)". Hereinafter, the Tp characteristics and Tp×Rs characteristics of Example 43 will be evaluated by comparing the reference values of Tp (84%) and Tp×Rs (76%) of Comparative Example 40 (α = 0°) shown in FIG. 20 described above with Tp and Tp×Rs of Example 43 (α = 10°) shown in FIG. 23.

[0451] (1) Oblique incident light in the - direction (35% ≤ Rc1 ≤ 50%) First, when the incident direction is the "- direction (θ = -45°)", in Example 43, if Rc1 is in the range of 35% or more and 50% or less, as shown in FIG. 23(b), Tp becomes equal to or higher than the reference value (84%). As a result, as shown in FIG. 23(d), Tp × Rs also becomes equal to or higher than the reference value (76%). Therefore, in the case of "-direction obliquely incident light (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 the range of 40% or more and 45% or less. Thereby, as shown in FIG. 23(b), Tp becomes 85.8% or more, and as shown in FIG. 23(d), Tp × Rs becomes 77% or more. Therefore, it can be seen that even better transmittance (Tp characteristics) and polarization separation characteristics (Tp × Rs characteristics) can be obtained.

[0453] (2) +-direction obliquely incident light (40% ≦ Rc1 ≦ 53%) On the other hand, when the incident direction is the "+ direction (θ = +45°)", in Example 43, if Rc1 is in the range of 40% or more and 53% or less, as shown in FIG. 23(b), Tp becomes equal to or higher than the reference value (84%). As a result, as shown in FIG. 23(d), Tp × Rs also becomes equal to or higher than the reference value (76%). Therefore, in the case of "+-direction obliquely incident light (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 the range of 45% or more and 50% or less. Thereby, as shown in FIG. 23(b), Tp becomes 85% or more, and as shown in FIG. 23(d), Tp × Rs becomes 76.5% or more. Therefore, it can be seen that even better transmittance (Tp characteristics) and polarization separation characteristics (Tp × Rs characteristics) can be obtained.

[0455] Regarding the contrast CR, as shown in Fig. 23(e), it can be seen that in both cases of "oblique incident light in the - direction (θ = -45°)" and "oblique incident light in the + direction (θ = +45°)", the higher the coating rate Rc1, the higher the contrast CR.

[0456] From the results of Example 43 above, it can be seen that even when the coating rate Rc1 varies during the manufacture of the grid, by inclining the convex strip portion 22, permeability (Tp characteristic) and polarization separation characteristic (Tp×Rs characteristic) equivalent to or better than the reference (Comparative Example 40) can be obtained. Therefore, it can be said that by changing the installation direction of the grid inclination structure of the polarization element 1 according to the incident direction (+ direction or - direction) of the oblique incident light, a polarization element 1 excellent in permeability (Tp characteristic) and polarization separation characteristic (Tp×Rs characteristic) with respect to the directional oblique incident light can be provided.

[0457] (Example 44) Next, referring to Fig. 24, Example 44 of the present invention will be described.

[0458] As shown in Fig. 24, a model of the polarization element 1 according to Example 44 was fabricated. In Example 44, a grid (a structure combining the convex strip portion 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 coating rate Rc2 of the second side surface 22b2 of the convex strip portion 22 was changed. In Example 44, in order to provide a grid inclination structure, the upper portion 22c of the convex strip portion 22 (the upper 50% portion of the convex strip portion 22) was inclined at an inclination angle α to one side in the width direction of the convex strip portion 22 (the right side in Fig. 24(a)). The inclination angle α in Example 44 was fixed at 10°.

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

[0460] The dimensions and shapes of the respective 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 values) Dt : 38 nm Ds : 17.5 nm (maximum value) Rc1 : 45% (fixed value) Rr1 : 55% (fixed value) Rc2 : 35%, 40%, 45%, 50%, 55% (variable values) Rr2 : 65%, 60%, 55%, 50%, 45% (variable values) 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 fabricated as described above, and Tp, Ts, Rp, Rs, and Tp×Rs were calculated respectively. At this time, the values of Tp, Ts, Rp, and Rs were calculated respectively when "oblique incident light in the - direction (θ = -45°)" was incident and when "oblique incident light in the + direction (θ = +45°)" was incident. Note that as the values of Tp, Ts, Rp, and Rs, the wavelength λ of the oblique incident light was varied in the range of 430 to 680 nm, and the average values of a plurality of Tp, Ts, Rp, and Rs values calculated for the oblique incident light of each wavelength λ were used. Also, by dividing Tp by Ts, the contrast (CR) of the transmitted light was also calculated (CR = Tp / Ts).

[0462] The relationships between the Tp characteristics, Rs characteristics, Tp×Rs characteristics, contrast CR according to Example 44 obtained as described above, and the coverage rate Rc2 of the first side surface 22b1 are shown in the graphs of FIGS. 24(b) to (e).

[0463] As shown in FIG. 24(c), the reflectance Rs of Example 44 maintains a high value of 90% or more regardless of the magnitude of the coverage rate Rc2 (35 to 55%) in both the case of "oblique incident light in the - direction (θ = -45°)" and the case of "oblique incident light in the + direction (θ = +45°)". Therefore, it can be seen that regardless of Rc2, a high Rs of 90% or more can be ensured, and excellent reflectivity (Rs characteristics) by the reflective film 30 can be exhibited.

[0464] On the other hand, as shown in FIGS. 24(b) and 24(d), for the Tp characteristics and Tp×Rs characteristics, the behaviors of the Tp characteristics and Tp×Rs characteristics according to the coverage rate Rc2 differ depending on whether the incident direction of the oblique incident light is " - direction (θ = -45°)" or " + direction (θ = +45°)". Hereinafter, the Tp characteristics and Tp×Rs characteristics of Example 44 are evaluated by comparing the reference values of Tp (84%) and Tp×Rs (76%) of Comparative Example 40 (α = 0°) shown in FIG. 20 described above with Tp and Tp×Rs of Example 44 (α = 10°) shown in FIG. 24.

[0465] (1) Oblique incident light in the - direction (35% ≤ Rc2 ≤ 55%) First, when the incident direction is the "- direction (θ = -45°)", in Example 44, if Rc2 is in the range of 35% or more and 55% or less, as shown in Fig. 24(b), Tp becomes equal to or higher than the reference value (84%). As a result, as shown in Fig. 24(d), Tp × Rs also becomes equal to or higher than the reference value (76%). Therefore, in the case of "- direction obliquely incident light (θ = -45°)", it can be seen that good transmittance (Tp characteristic) and polarization separation characteristic (Tp × Rs characteristic) 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 the range of 40% or more and 55% or less. Thereby, as shown in Fig. 24(b), Tp becomes 85.5% or more, and as shown in Fig. 24(d), Tp × Rs becomes 77% or more. Therefore, it can be seen that even better transmittance (Tp characteristic) and polarization separation characteristic (Tp × Rs characteristic) can be obtained.

[0467] (2) + direction obliquely incident light (35% ≤ Rc2 ≤ 45%) On the other hand, when the incident direction is the "+ direction (θ = +45°)", in Example 44, if Rc2 is in the range of 35% or more and 45% or less, as shown in Fig. 24(b), Tp becomes equal to or higher than the reference value (84%). As a result, as shown in Fig. 24(d), Tp × Rs also becomes equal to or higher than the reference value (76%). Therefore, in the case of "+ direction obliquely incident light (θ = +45°)", it can be seen that good transmittance (Tp characteristic) and polarization separation characteristic (Tp × Rs characteristic) 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 the range of 40% or more and 45% or less. Thereby, as shown in Fig. 24(b), Tp becomes about 85%, and as shown in Fig. 24(d), Tp × Rs becomes 76.5% or more. Therefore, it can be seen that even better transmittance (Tp characteristic) and polarization separation characteristic (Tp × Rs characteristic) can be obtained.

[0469] Regarding the contrast CR, as shown in Fig. 24(e), in both cases of "oblique incident light in the - direction (θ = -45°)" and "oblique incident light in the + direction (θ = +45°)", the higher the coating rate Rc2, the higher the contrast CR. In particular, when it is 45% or more, it can be seen that the contrast CR increases rapidly.

[0470] From the results of Example 44 above, even when the coating rate Rc2 varies during the manufacture of the grid, by inclining the rib portion 22, it can be seen that permeability (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) equivalent to or better than the reference (Comparative Example 40) can be obtained. Therefore, by changing the installation direction of the grid inclination structure of the polarization element 1 according to the incident direction of the oblique incident light (+ direction or - direction), it can be said that a polarization element 1 excellent in permeability (Tp characteristics) and polarization separation characteristics (Tp×Rs characteristics) with respect to the directional oblique incident light can be provided.

[0471] <2. Verification Results of the Composition of the Organic Material (Imprint Photo-Curable Acrylic Resin)>

[0472] As the imprint photo-curable acrylic resin, Examples 51 to 58 and Comparative Examples 51 to 57 were prepared.

[0473] The viscosities of the imprint photo-curable acrylic resins according to Examples 51 to 58 and Comparative Examples 51 to 57 were measured. The viscosity was measured using a cone plate in the product named "Brookfield Viscometer" manufactured by Eiko Seiki Co., Ltd.

[0474] The YI values of the cured products of the imprint photo-curable acrylic resins according to Examples 51 to 58 and Comparative Examples 51 to 57 were measured after holding at 150°C for 500 hours (heat treatment). The YI values were calculated based on the measurement results using the product named "Ultraviolet-Visible Near-Infrared Spectrophotometer V-770" manufactured by JASCO Corporation. The measurement conditions and the calculation method of the YI values were the same as those in the above embodiment.

[0475] For the cured products of the imprint photo-curable acrylic resins according to Examples 51 to 58 and Comparative Examples 51 to 57, the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 680 nm or less, and the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 510 nm or less were measured before heat treatment (held at 150 °C for 500 hours). Further, after holding the cured products of the imprint photo-curable acrylic resins according to Examples 51 to 58 and Comparative Examples 51 to 57 at 150 °C for 500 hours, the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 680 nm or less, and the average transmittance of the cured product with respect to light in the wavelength range of 430 nm or more and 510 nm or less were measured. The average transmittance was calculated by measuring the transmittance every 1 nm in the wavelength range of 430 nm or more and 680 nm or less and simply averaging the obtained 251 measurement data. The average transmittance was measured using the product name "UV-Visible Near-Infrared Spectrophotometer V-770" manufactured by JASCO Corporation.

[0476] The storage elastic modulus at 30 °C, the storage elastic modulus at 110 °C, the storage elastic modulus at 120 °C, and the storage elastic modulus at 130 °C of the cured products of the imprint photo-curable acrylic resins according to Examples 51 to 58 and Comparative Examples 51 to 57 were measured. The storage elastic modulus was measured using the product name "DMA7100" manufactured by Hitachi High-Tech Corporation. Sheets of the cured products of the imprint photo-curable acrylic resins according to Examples 51 to 58 and Comparative Examples 51 to 57 were cut into 20 mm in length and 3 mm in width, and in the tensile mode, at a constant frequency (1 Hz), the temperature was raised at 5 °C / min, and the storage elastic modulus at 25 °C to 300 °C was measured.

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

[0478] The compositions and viscosities of the imprint photo-curable acrylic resins of Examples 51 to 54 are shown in Table 1 below. The YI values, average transmittances, storage elastic moduli, and glass transition temperatures Tg of the cured products of the imprint photo-curable acrylic resins according to Examples 51 to 54 are shown in Table 2 below.

[0479] The compositions and viscosities of the imprint photo-curable acrylic resins of Examples 55 to 58 are shown in Table 3 below. The YI values, average transmittances, storage elastic moduli, and glass transition temperatures Tg of the cured products of the imprint photo-curable acrylic resins according to Examples 55 to 58 are shown in Table 4 below.

[0480] The compositions and viscosities of the imprint photo-curable acrylic resins of Comparative Examples 51 to 54 are shown in Table 5 below. The YI values, average transmittances, storage elastic moduli, and glass transition temperatures Tg of the cured products of the imprint photo-curable acrylic resins according to Comparative Examples 51 to 54 are shown in Table 6 below.

[0481] The compositions and viscosities of the imprint photo-curable acrylic resins of Comparative Examples 55 to 57 are shown in Table 7 below. The YI values, average transmittances, storage elastic moduli, and glass transition temperatures Tg of the cured products of the imprint photo-curable acrylic resins according to Comparative Examples 55 to 57 are shown in Table 8 below.

[0482] Note that the unit of the content in Tables 1, 3, 5, and 7 is mass%. Also, the viscosities in Tables 1, 3, 5, and 7 are the viscosities [mPa·s] at 25 °C.

[0483]

Table 1

[0484]

Table 2

[0485] [Example 51] As shown in Table 1, Example 51 contains only Resin (A), Resin (B), and Resin (C) as photopolymerizable components, and further contains a photopolymerization initiator. As Resin (A), phenyl ethyl acrylate (PEA) was used. As the phenyl ethyl acrylate, the product name "Viscoat #192HP" manufactured by Osaka Organic Chemical Industry Co., Ltd. was used. As Resin (B), bisacrylic acid (2,2-dimethylethylene) (5-ethyl-1,3-dioxane-2,5-diyl) methylene and 1,6-hexanediol diacrylate were used. As bisacrylic acid (2,2-dimethylethylene) (5-ethyl-1,3-dioxane-2,5-diyl) methylene, the product name "KAYARAD R-604" manufactured by Nippon Kayaku Co., Ltd. was used. As 1,6-hexanediol diacrylate, the product name "A-HD-N" manufactured by Shin-Nakamura Chemical Co., Ltd. was used. As Resin (C), dipentaerythritol hexaacrylate (DPHA) was used. As the dipentaerythritol hexaacrylate, the product name "KAYARAD DPHA" manufactured by Nippon Kayaku Co., Ltd. was used. As the photopolymerization initiator, the product name "Irgacure819" manufactured by IGM Resins B.V. was used. In Example 51, the content of Resin (A) in the entire photopolymerizable component 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 bisacrylic acid (2,2-dimethylethylene) (5-ethyl-1,3-dioxane-2,5-diyl) methylene in Resin (B) was 1 to 1. In Example 51, when the content of the entire photopolymerizable component was 100% by mass, the content of the photopolymerization initiator was 0.5% by mass.

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

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

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

[0489] In the cured product of Example 51, the difference ΔA in the average transmittance for light in the wavelength range 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%. In the cured product of Example 51, the difference ΔA in the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less before and after heat treatment was +0.1%. From the above results, it was confirmed that even when the cured product of Example 51 was heat-treated at 150°C, the average transmittance for light in the wavelength range of 430 nm or more and 680 nm or less, and the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less hardly decreased.

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

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

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

[0493] As shown in Table 1, the viscosity of the photocurable acrylic resin for imprinting in Example 52 was 20.54 mPa·s. Also, in the photocurable acrylic resin for imprinting in Example 52, the content of resin (C) was higher compared to the photocurable acrylic resin for imprinting in Example 51. Thus, it is presumed that the viscosity of the photocurable acrylic resin for imprinting in Example 52 became higher than the viscosity of the photocurable acrylic resin for imprinting in Example 51.

[0494] As shown in Table 2, the YI value after heat treatment in the cured product of the photocurable acrylic resin for imprinting in Example 52 was 1.6. From the above results, it was confirmed that even when the cured product of Example 52 was subjected to heat treatment at 150°C, a low YI value could be maintained. Also, in the photocurable acrylic resin for imprinting in Example 52, the content of resin (C) was higher compared to the photocurable acrylic resin for imprinting in Example 51. Thus, it is presumed that the YI value of the cured product of the photocurable acrylic resin for imprinting in Example 52 became higher than the YI value of the cured product of the photocurable acrylic resin for imprinting in Example 51.

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

[0496] In the cured product of Example 52, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in the average transmittance of light in the wavelength range of 430 nm or more and 680 nm or less before and after heat treatment was +0.1%. In the cured product of Example 52, the difference ΔA in the average transmittance of light in the wavelength range of 430 nm or more and 510 nm or less before and after heat treatment was +0.8%. From the above results, it was confirmed that even when the cured product of Example 52 was heat-treated at 150 °C, the average transmittance of light in the wavelength range of 430 nm or more and 680 nm or less, and the average transmittance of light in the wavelength range of 430 nm or more and 510 nm or less hardly decreased. Also, in the imprint photo-curable acrylic resin of Example 52, the content of resin (C) was higher compared to the imprint photo-curable acrylic resin of Example 51. Accordingly, it is presumed that the difference ΔA in the average transmittance of light in the wavelength range of 430 nm or more and 510 nm or less of the cured product of the imprint photo-curable acrylic resin of Example 52 became slightly larger than the difference ΔA in the average transmittance of the cured product of the imprint photo-curable acrylic resin of Example 51.

[0497] As shown in Table 2, the storage modulus at 30 °C of the cured product of the imprint photo-curable acrylic resin of Example 52 was 3.1×10 9 Pa. The storage modulus at 110 °C of the cured product of the imprint photo-curable acrylic resin of Example 52 was 5.1×10 8 Pa. The storage modulus at 120 °C of the cured product of the imprint photo-curable acrylic resin of Example 52 was 3.9×10 8 Pa. The storage modulus at 130 °C of the cured product of the imprint photo-curable acrylic resin of Example 52 was 3.3×10 8 Pa. From the above results, the cured product of Example 52 had a storage modulus of 3.1×10 9It was confirmed that it has a high storage elastic modulus of Pa. Also, it was confirmed that even when the cured product of Example 52 was heat-treated at 150 °C, a decrease in the storage elastic modulus was suppressed. Further, in the imprint photo-curable acrylic resin of Example 52, the content of resin (C) is high as compared with the imprint photo-curable acrylic resin of Example 51. Accordingly, it is presumed that the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin of Example 52 became larger than that of the cured product of the imprint photo-curable acrylic resin of Example 51.

[0498] As shown in Table 2, the glass transition temperature Tg of the cured product of the imprint photo-curable acrylic resin of Example 52 was 103.1 °C. From the above results, although the cured product of Example 52 has a glass transition temperature Tg of less than 110 °C, it was confirmed that the YI value after heat treatment at 150 °C can be kept low, the average transmittance after heat treatment at 150 °C can be maintained high, and further, a decrease in the storage elastic modulus after heat treatment at 150 °C can be suppressed.

[0499] [Example 53] As shown in Table 1, Example 53 is different from Examples 51 and 52 only in the contents of resins (A) to (C). In Example 53, the content of resin (A) in the whole photopolymerizable component was 23.3% by mass, the content of resin (B) was 46.7% by mass, and the content of resin (C) was 30% by mass. Also, in Example 53 as well, the ratio of 1,6-hexanediol diacrylate to bisacrylic acid (2,2-dimethylethylene)(5-ethyl-1,3-dioxane-2,5-diyl)methylene in resin (B) was 1 to 1.

[0500] As shown in Table 1, the viscosity of the photocurable acrylic resin for imprinting in Example 53 was 68.12 mPa·s. Also, in the photocurable acrylic resin for imprinting in Example 53, the content of resin (C) was higher compared to the photocurable acrylic resin for imprinting in Example 52. Thus, it is presumed that the viscosity of the photocurable acrylic resin for imprinting in Example 53 became higher than the viscosity of the photocurable acrylic resin for imprinting in Example 52.

[0501] As shown in Table 2, the YI value after heat treatment in the cured product of the photocurable acrylic resin for imprinting in Example 53 was 2.3. From the above results, it was confirmed that even when the cured product of Example 53 was heat-treated at 150°C, a low YI value could be maintained. Also, in the photocurable acrylic resin for imprinting in Example 53, the content of resin (C) was higher compared to the photocurable acrylic resin for imprinting in Example 52. Thus, it is presumed that the YI value of the cured product of the photocurable acrylic resin for imprinting in Example 53 became higher than the YI value of the cured product of the photocurable acrylic resin for imprinting in Example 52.

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

[0503] In the cured product of Example 53, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in the average transmittance of light in the wavelength region of 430 nm or more and 680 nm or less before and after heat treatment was +0.2%. In the cured product of Example 53, the difference ΔA in the average transmittance of light in the wavelength region of 430 nm or more and 510 nm or less before and after heat treatment was +1.1%. From the above results, it was confirmed that even when the cured product of Example 53 was heat-treated at 150 °C, the average transmittance of light in the wavelength region of 430 nm or more and 680 nm or less, and the average transmittance of light in the wavelength region of 430 nm or more and 510 nm or less hardly decreased. Also, in the imprint photo-curable acrylic resin of Example 53, the content of resin (C) was higher compared to the imprint photo-curable acrylic resin of Example 52. Accordingly, it is presumed that the difference ΔA in the average transmittance of the cured product of the imprint photo-curable acrylic resin of Example 53 became larger than the difference ΔA in the average transmittance of the cured product of the imprint photo-curable acrylic resin of Example 52.

[0504] As shown in Table 2, the storage modulus at 30 °C of the cured product of the imprint photo-curable acrylic resin of Example 53 was 3.2×10 9 Pa. The storage modulus at 110 °C of the cured product of the imprint photo-curable acrylic resin of Example 53 was 1.1×10 9 Pa. The storage modulus at 120 °C of the cured product of the imprint photo-curable acrylic resin of Example 53 was 9.1×10 8 Pa. The storage modulus at 130 °C of the cured product of the imprint photo-curable acrylic resin of Example 53 was 8.0×10 8 Pa. From the above results, the cured product of Example 53 had a storage modulus of 3.2×10 9It was confirmed that it has a high storage elastic modulus of Pa. Further, it was confirmed that even when the cured product of Example 53 was heat-treated at 150 °C, a decrease in the storage elastic modulus was suppressed. Further, in the imprint photo-curable acrylic resin of Example 53, the content of resin (C) is higher compared to the imprint photo-curable acrylic resin of Example 52. Thus, it is presumed that the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin of Example 53 became larger than the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin of Example 52.

[0505] As shown in Table 2, the glass transition temperature Tg of the cured product of the imprint photo-curable acrylic resin of Example 53 was 103.8 °C. From the above results, although the cured product of Example 53 has a glass transition temperature Tg of less than 110 °C, it was confirmed that the YI value after heat treatment at 150 °C can be kept low, the average transmittance after heat treatment at 150 °C can be maintained high, and the decrease in the storage elastic modulus after further heat treatment at 150 °C can be suppressed.

[0506] [Example 54] As shown in Table 1, in Example 54, only the contents of resin (A) to resin (C) are different from those in Examples 51 to 53. In Example 54, the content of resin (A) in the entire photopolymerizable component was 42% by mass, the content of resin (B) was 43% by mass, and the content of resin (C) was 15% by mass. Further, in Example 54, among resin (B), the content of 1,6-hexanediol diacrylate was 42% by mass, and the content of bisacrylic acid (2,2-dimethylethylene) (5-ethyl-1,3-dioxane-2,5-diyl)methylene was 1% by mass.

[0507] As shown in Table 1, the viscosity of the photocurable acrylic resin for imprinting in Example 54 was 13.45 mPa·s. Also, in the photocurable acrylic resin for imprinting in Example 54, the content of 1,6 - hexanediol diacrylate was higher compared to Examples 52 and 53. Accordingly, it is presumed that the viscosity of the photocurable acrylic resin for imprinting in Example 54 became lower than the viscosities of the photocurable acrylic resins for imprinting in Examples 52 and 53.

[0508] As shown in Table 2, the YI value after heat treatment in the cured product of the photocurable acrylic resin for imprinting in Example 54 was 1.4. From the above results, it was confirmed that even when the cured product of Example 54 was subjected to heat treatment at 150 °C, a low YI value could be maintained. Also, in the photocurable acrylic resin for imprinting in Example 54, the content of 1,6 - hexanediol diacrylate was higher compared to Examples 52 and 53. Accordingly, it is presumed that the YI value of the cured product of the photocurable acrylic resin for imprinting in Example 54 became lower than the YI values of the cured products of the photocurable acrylic resins for imprinting in Examples 52 and 53.

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

[0510] In the cured product of Example 54, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in the average transmittance of light in the wavelength range of 430 nm or more and 680 nm or less before and after heat treatment was -0.1%. In the cured product of Example 54, the difference ΔA in the average transmittance of light in the wavelength range of 430 nm or more and 510 nm or less before and after heat treatment was +0.3%. From the above results, it was confirmed that even when the cured product of Example 54 was heat-treated at 150 °C, the average transmittance of light in the wavelength range of 430 nm or more and 680 nm or less and the average transmittance of light in the wavelength range of 430 nm or more and 510 nm or less hardly decreased. Further, in the imprint photo-curable acrylic resin of Example 54, the content of 1,6-hexanediol diacrylate was higher compared to Examples 52 and 53. Accordingly, it is presumed that the difference ΔA in the average transmittance of the cured product of the imprint photo-curable acrylic resin of Example 54 became smaller than the difference ΔA in the average transmittance of the cured products of the imprint photo-curable acrylic resins of Examples 52 and 53.

[0511] As shown in Table 2, the storage elastic modulus at 30 °C of the cured product of the imprint photo-curable acrylic resin of Example 54 was 2.3×10 9 Pa. The storage elastic modulus at 110 °C of the cured product of the imprint photo-curable acrylic resin of Example 54 was 1.9×10 8 Pa. The storage elastic modulus at 120 °C of the cured product of the imprint photo-curable acrylic resin of Example 54 was 2.2×10 8 Pa. The storage elastic modulus at 130 °C of the cured product of the imprint photo-curable acrylic resin of Example 54 was 2.3×10 8 Pa. From the above results, the cured product of Example 54 had a storage elastic modulus of 2.3×10 9It was confirmed that it has a high storage elastic modulus of Pa. Further, it was confirmed that even when the cured product of Example 54 was heat-treated at 150°C, the decrease in the storage elastic modulus was suppressed. Further, in the imprint photo-curable acrylic resin of Example 54, the content of resin (C) is high as compared with Example 51. Thus, it is presumed that the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin of Example 54 became larger than that of the cured product of the imprint photo-curable acrylic resin of Example 51.

[0512] As shown in Table 2, the glass transition temperature Tg of the cured product of the imprint photo-curable acrylic resin of Example 54 was 58.0°C. From the above results, although the glass transition temperature Tg of the cured product of Example 54 is less than 110°C, it was confirmed that the YI value after heat treatment at 150°C can be suppressed low, the average transmittance after heat treatment at 150°C can be maintained high, and further, the decrease in the storage elastic modulus after heat treatment at 150°C can be suppressed. Further, in the imprint photo-curable acrylic resin of Example 54, the content of 1,6-hexanediol diacrylate is high as compared with Example 52 and Example 53. Thus, it is presumed that the glass transition temperature Tg of the cured product of the imprint photo-curable acrylic resin of Example 54 became lower than that of the cured products of the imprint photo-curable acrylic resins of Example 52 and Example 53.

[0513]

Table 3

[0514]

Table 4

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

[0516] As shown in Table 3, the viscosity of the imprint - use photocurable acrylic resin of Example 55 was 85.01 mPa·s. Also, in the imprint - use photocurable acrylic resin of Example 55, compared with Example 54, the content ratio of 1,6 - hexanediol diacrylate was lower and the content ratio of bisacrylic acid (2,2 - dimethylethylene)(5 - ethyl - 1,3 - dioxane - 2,5 - diyl)methylene was higher. Thus, it is presumed that the viscosity of the imprint - use photocurable acrylic resin of Example 55 became higher than the viscosity of the imprint - use photocurable acrylic resin of Example 54.

[0517] As shown in Table 4, the YI value after heat treatment in the cured product of the imprint - use photocurable acrylic resin of Example 55 was 1.1. From the above results, it was confirmed that even when the cured product of Example 55 was subjected to heat treatment at 150°C, a low YI value could be maintained.

[0518] As shown in Table 4, the average transmittance of the cured product of the imprint photo-curable acrylic resin of Example 55 for light in the wavelength range of 430 nm or more and 680 nm or less before heat treatment was 91.9%, and the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less before heat treatment was 91.7%. Further, the average transmittance of the cured product of the imprint photo-curable acrylic resin of Example 55 for light in the wavelength range of 430 nm or more and 680 nm or less after heat treatment was 92.0%, and the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less after heat treatment was 91.5%.

[0519] In the cured product of Example 55, the difference ΔA in the average transmittance for light in the wavelength range 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%. In the cured product of Example 55, the difference ΔA in the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less before and after heat treatment was +0.1%. From the above results, it was confirmed that even when the cured product of Example 55 was subjected to a heat treatment at 150 °C, the average transmittance for light in the wavelength range of 430 nm or more and 680 nm or less and the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less hardly decreased.

[0520] As shown in Table 4, the storage elastic modulus of the cured product of the imprint photo-curable acrylic resin of Example 55 at 30 °C was 2.6×10 9 Pa. The storage e...

Claims

1. A substrate made of an inorganic material, a grid structure integrally formed of an organic material, having a base portion provided on the substrate and a plurality of protruding ridges protruding from the base portion, a functional film made of a metal material and covering a part of the ridges, comprising: the organic material is a cured product of an imprintable photocurable acrylic resin containing a photopolymerizable component, the photopolymerizable component resin (A), resin (B), including, the resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, the resin (B) is a bifunctional compound, the content of the resin (A) with respect to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less, the content of the resin (B) with respect to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less, a wire grid polarizing element.

2. the photopolymerizable component further includes resin (C), the resin (C) is an acrylate monomer having three or more functional groups, the content of the resin (C) with respect to the entire photopolymerizable component is 1% by mass or more and 30% by mass or less, the wire grid polarizing element according to claim 1.

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

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

5. the resin (B) includes 1,6-hexanediol diacrylate, and one of (octahydro-4,7-methano-1H-indenediyl) bis(methylene) diacrylate and bisacrylic acid (2,2-dimethylethylene) (5-ethyl-1,3-dioxane-2,5-diyl) methylene, the wire grid polarizing element according to claim 4.

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

7. The wire grid polarizing element according to claim 1 or 2, wherein the viscosity of the imprint photo-curable acrylic resin at 25°C is 90 mPa·s or less.

8. After the cured product of the imprint photo-curable acrylic resin is held at 150°C for 500 hours, The wire grid polarizing element according to claim 1 or 2, wherein the YI value of the cured product is 3.0 or less.

9. The storage elastic modulus of the cured product of the imprint photo-curable acrylic resin at 30°C is 2.0×10 ９ Pa or more, The storage elastic modulus of the cured product at 120°C is 1.3×10 ８ Pa or more. The wire grid polarizing element according to claim 1 or 2.

10. The storage elastic modulus of the cured product at 130°C is 1.4×10 ８ Pa or more. The wire grid polarizing element according to claim 9.

11. After the cured product of the imprint photo-curable acrylic resin is held at 150°C for 500 hours, The average transmittance of the cured product for light in the wavelength range of 430 nm or more and 680 nm or less is 91% or more, The wire grid polarizing element according to claim 1 or 2, wherein the average transmittance of the cured product for light in the wavelength range of 430 nm or more and 510 nm or less is 90% or more.

12. The ridge portion has a tapered shape in which the width becomes narrower as it moves away from the base portion, The functional film covers the tip of the ridge portion and the upper side of at least one side surface, and does not cover the lower sides of both side surfaces of the ridge portion and the base portion, When the coverage rate (Rc) of the side surface of the ridge portion by the functional film is the ratio of the height (Hx) of the portion of the side surface of the ridge portion covered by the functional film to the height (H) of the ridge portion, the coverage rate (Rc) is 30% or more and 70% or less. The wire grid polarizing element according to claim 1 or 2.

13. At least the portion of the ridge portion covered by the functional film is inclined at an inclination angle (α) of more than 0° and 15° or less with respect to the normal direction of the substrate. The wire grid polarizing element according to claim 1 or 2.

14. The ridge portion is bent in the middle in the height direction of the ridge portion, The wire grid polarizing element according to claim 13, wherein the upper part of the ridge portion from the bent position is inclined at the inclination angle (α) with respect to the normal direction of the substrate.

15. The wire grid polarizing element according to claim 13, wherein the entire ridge portion is inclined at the inclination angle (α) with respect to the normal direction of the substrate.

16. The wire grid polarizing element according to claim 13, wherein the tilt angle (α) is 5° or more and 10° or less.

17. The functional film covers the tips of the convex strip portions and the upper sides of both side surfaces thereof, The wire grid polarizing element according to claim 13, wherein the coverage rate (Rc) of both side surfaces of the convex strip portion by the functional film is 30% or more and 70% or less.

18. The wire grid polarizing element according to claim 17, wherein the coverage rate (Rc) of the first side surface on the side where the convex strip portion is inclined among both side surfaces of the convex strip portion is 35% or more and 50% or less.

19. The wire grid polarizing element according to claim 18, wherein the coverage rate (Rc) of the first side surface is 40% or more and 53% or less.

20. The wire grid polarizing element according to claim 17, wherein the coverage rate (Rc) of the second side surface on the side opposite to the side where the convex strip portion is inclined among both side surfaces of the convex strip portion is 35% or more and 55% or less.

21. The wire grid polarizing element according to claim 20, wherein the coverage rate (Rc) of the second side surface is 35% or more and 45% or less.

22. A method for manufacturing the wire grid polarizing element according to claim 1 or 2, forming a grid structure material made of an organic material on a substrate made of an inorganic material; forming a grid structure in which a base portion provided on the substrate and a plurality of convex strip portions protruding from the base portion are integrally formed by performing nanoimprint on the grid structure material; forming a functional film covering a part of the convex strip portion using a metal material; including The organic material is a cured product of an imprint photocurable acrylic resin containing a photopolymerizable component, The photopolymerizable component resin (A), resin (B), including The resin (A) is a monofunctional acrylate monomer having one or both of a phenyl group and a benzyl group, The resin (B) is a bifunctional compound, The content rate of the resin (A) with respect to the entire photopolymerizable component is 20% by mass or more and 42% by mass or less, A method for manufacturing a wire grid polarizing element, wherein the content rate of the resin (B) with respect to the entire photopolymerizable component is 43% by mass or more and 66% by mass or less.

23. The imprint photocurable acrylic resin further includes a photopolymerization initiator for polymerizing the photopolymerizable component, The step of forming the grid structure mixing the resin (A) and the resin (B); mixing the photopolymerization initiator with the mixed resin of the resin (A) and the resin (B); A method for manufacturing a wire grid polarizing element according to claim 22, comprising:

24. The photopolymerizable component further includes a resin (C), The resin (C) is an acrylate monomer having three or more functional groups, The content of the resin (C) with respect to the entire photopolymerizable component is 1% by mass or more and 30% by mass or less, The step of forming the grid structure includes: generating a first mixed resin by mixing the resin (A) and the resin (B); generating a second mixed resin by mixing the resin (C) with the first mixed resin; A method for manufacturing a wire grid polarizing element according to claim 22, comprising:

25. a light source; a polarizing beam splitter arranged such that incident light from the light source is incident at an incident angle of 30° or more and 60° or less, and separating the incident light into a first polarization and a second polarization; a reflective liquid crystal display element arranged such that the first polarization reflected by the polarizing beam splitter or the second polarization transmitted through the polarizing beam splitter is incident, and reflecting and modulating the incident first polarization or second polarization; a lens arranged such that the first polarization or the second polarization reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter; comprising A projection display device, wherein the polarizing beam splitter is composed of the wire grid polarizing element according to claim 1 or 2.

26. A vehicle comprising the projection display device according to claim 25.

Images