Photocuring acrylic resin for imprinting

Abstract

The present invention provides a photocurable acrylic resin for imprint, which reduces the viscosity of an uncured resin composition and enables the cured resin composition to have excellent heat resistance. The photocurable acrylic resin for imprint contains a photopolymerization component, the photopolymerization component comprises a resin (A) and a resin (B), the resin (A) is (octahydro-4, 7-methylene-1H-indene diyl) bis (methylene) diacrylate, the resin (B) is a bifunctional acrylate monomer having a viscosity of 10 mPa * s or less at 25 DEG C, and the photopolymerization component comprises a photopolymerization component, the content ratio of the resin (A) relative to the whole photopolymerization component is 20-40 mass%, and the total content ratio of the resin (A) and the resin (B) relative to the whole photopolymerization component is 70 mass% or less.

Description

Technical Field

[0001] The present invention relates to a photocurable acrylic resin used in imprint forming. Background Art

[0002] Imprint forming of an uncured resin layer composed of an uncured resin composition is widely used as a technique for manufacturing resin optical components having a fine concavo-convex structure. In imprint forming, by pressing the fine concavo-convex shape of a master disk onto an uncured resin layer formed on a substrate, the uncured resin layer is cured in this state, and then the master disk is peeled off, whereby a fine concavo-convex shape can be formed on the substrate.

[0003] In imprint forming, if the thickness (layer thickness) of the uncured resin layer when pressing the master disk is uneven, the peeling force applied when peeling the master disk from the cured resin layer (hereinafter referred to as "cured resin layer") becomes uneven within the plane of the cured resin layer. As a result, it is possible that a part of the cured resin layer peels off from the substrate. In addition, the cured resin layer peeled off from the substrate remains on the master disk, and the master disk cannot be reused. Moreover, when the master disk is peeled off, the fine concavo-convex shape transferred to the cured resin layer is deformed, and it is possible that the optical characteristics caused by the fine concavo-convex structure deteriorate.

[0004] In addition, in imprint forming, if the followability of the uncured resin composition to the fine concavo-convex shape is low when pressing the master disk, a portion where the fine concavo-convex shape of the master disk is not transferred is generated in the uncured resin layer.

[0005] Therefore, in order to make the layer thickness of the uncured resin layer uniform when pressing the master disk and improve the followability of the uncured resin composition to the fine concavo-convex shape, a technique for reducing the viscosity of the uncured resin composition has been developed (for example, Patent Documents 1 and 2).

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-125559

[0009] Patent Document 2: Japanese Patent No. 4824068 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] In order to reduce the viscosity of the uncured resin composition, it is conceivable to increase the content ratio of monofunctional monomers and low-viscosity bifunctional monomers in the resin composition.

[0012] However, if the content ratio of the monofunctional monomer and the bifunctional monomer with low viscosity is increased, there is a problem that the heat resistance of the cured resin layer decreases.

[0013] Therefore, the present invention has been completed in view of the above-described circumstances, and an object thereof is to provide a photocurable acrylic resin for imprinting that reduces the viscosity of an uncured resin composition and has excellent heat resistance of the cured resin composition.

[0014] Technical solution for solving the problem

[0015] In order to solve the above problems, according to one aspect of the present invention, there is provided a photocurable acrylic resin for imprinting, which contains a photopolymerizable component.

[0016] The photopolymerizable component includes: resin (A) and resin (B).

[0017] The resin (A) is (octahydro-4,7-methano-1H-indenediyl)bis(methylene)diacrylate.

[0018] The resin (B) is a bifunctional acrylate monomer having a viscosity of 10 mPa·s or less at 25°C.

[0019] The content ratio of the resin (A) relative to the whole photopolymerizable component is 20% by mass or more and 40% by mass or less.

[0020] The total content ratio of the resin (A) and the resin (B) relative to the whole photopolymerizable component is 70% by mass or less.

[0021] The viscosity of the photocurable acrylic resin for imprinting at 25°C is 35 mPa·s or less.

[0022] The photopolymerizable component further includes resin (C).

[0023] The resin (C) is an acrylate monomer having a viscosity of 10 mPa·s or less at 25°C.

[0024] The total content ratio of the resin (B) and the resin (C) relative to the whole photopolymerizable component is 50% by mass or more and 70% by mass or less.

[0025] The resin (C) is a monofunctional acrylate monomer.

[0026] The resin (C) is isobornyl acrylate.

[0027] The photopolymerizable component further includes resin (D).

[0028] The resin (D) is a polyfunctional acrylate monomer having three or more functional groups.

[0029] The content ratio of the resin (D) relative to the whole of the photopolymerizable component is more than 0% by mass and 20% by mass or less.

[0030] The resin (D) is selected from one or more of the group consisting of trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and polyfunctional polyester acrylate.

[0031] The resin (B) is a bifunctional acrylate monomer in which acryloyl groups are respectively bonded to both ends of a linear structure composed of a hydrocarbon group, or is a bifunctional acrylate monomer in which acryloyl groups are respectively bonded to both ends of a linear structure having an ether bond.

[0032] The resin (B) is a bifunctional acrylate monomer represented by the following chemical formula (I), and in the chemical formula (I), n is an integer of 1 or more and 9 or less.

[0033] CH2=CHCOO(CH2) n OOCCH=CH2…(I)

[0034] In the chemical formula (I), n is an integer of 6 or more and 9 or less.

[0035] In the chemical formula (I), n is 6 or 9.

[0036] After the cured product of the imprinting photocurable acrylic resin is maintained at 120 °C for 500 hours,

[0037] The YI value of this cured product is 3 or less.

[0038] The storage modulus of the cured product of the imprinting photocurable acrylic resin at 30 °C is 1.6×10 9 Pa or more,

[0039] The storage modulus of this cured product at 120 °C is 3.9×10 8 Pa or more.

[0040] After the cured product of the imprinting photocurable acrylic resin is maintained at 120 °C for 500 hours,

[0041] The average transmittance of this cured product with respect to light in the wavelength range of 430 nm or more and 680 nm or less is 91% or more,

[0042] The average transmittance of this cured product with respect to light in the wavelength range of 430 nm or more and 510 nm or less is 90% or more.

[0043] The imprinting photocurable acrylic resin further contains a photopolymerization initiator for polymerizing the photopolymerizable component.

[0044] Advantages of the Invention

[0045] According to the present invention, a photocurable acrylic resin for imprinting can be provided, which reduces the viscosity of the uncured resin composition and makes the heat resistance of the cured resin composition excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A cross-sectional view schematically showing a wire grid polarizing element according to an embodiment of the present invention.

[0047] Figure 2 A top view schematically showing the wire grid polarizing element according to the embodiment.

[0048] Figure 3 A cross-sectional view schematically showing a specific example of the tapered shape of the ridge portion of the grid structure according to the embodiment.

[0049] Figure 4 A cross-sectional view schematically showing a specific example of the shape of the concave portion of the grid structure according to the embodiment.

[0050] Figure 5 A cross-sectional view schematically showing the wire grid polarizing element according to the embodiment.

[0051] Figure 6 A cross-sectional view schematically showing a specific example of the shape of the reflective film according to the embodiment.

[0052] Figure 7 A cross-sectional view schematically showing the polarizing element covered with a protective film according to the embodiment.

[0053] Figure 8 A cross-sectional view schematically showing a modified example of the polarizing element covered with a protective film according to the embodiment.

[0054] Figure 9 A perspective view schematically showing the polarizing element provided with a heat dissipation member according to the embodiment.

[0055] Figure 10 A photograph showing the actual grid structure and reflective film according to the embodiment.

[0056] Figure 11 A process chart showing the manufacturing method of the wire grid polarizing element according to the embodiment.

[0057] Figure 12 A process chart showing the manufacturing method of the conventional wire grid polarizing element.

[0058] Figure 13 A process chart showing the manufacturing method of the master disk according to the embodiment.

[0059] Figure 14 Schematic diagram showing a head-up display device as an example of the projection display device according to this embodiment.

[0060] Figure 15 Schematic diagram showing a first specific example of the projection display device according to this embodiment.

[0061] Figure 16 Schematic diagram showing a second specific example of the projection display device according to this embodiment.

[0062] Figure 17 Schematic diagram showing a third specific example of the projection display device according to this embodiment.

[0063] Figure 18 Diagram for explaining the polarization element according to Comparative Example 1.

[0064] Figure 19 Diagram for explaining the polarization element according to Comparative Example 2.

[0065] Figure 20 Diagram for explaining the polarization element according to Comparative Example 3.

[0066] Figure 21 Diagram for explaining the polarization element according to Example 1.

[0067] Figure 22 Diagram for explaining the comparison result between Example 1 and Comparative Example 2.

[0068] Figure 23 Diagram for explaining the polarization element according to Example 2.

[0069] Figure 24 Diagram for explaining the polarization element according to Example 3.

[0070] Figure 25 Diagram for explaining the polarization element according to Example 4.

[0071] Figure 26 Diagram for explaining the polarization element according to Example 5.

[0072] Figure 27 Diagram for explaining the polarization element according to Example 6.

[0073] Figure 28 Diagram for explaining the polarization element according to Example 7.

[0074] Figure 29 Diagram for explaining the polarization element according to Example 8.

[0075] Figure 30 A diagram for explaining the comparison results between Example 9 and Comparative Example 4.

[0076] Figure 31 A diagram for explaining the comparison results between Example 9 and Comparative Example 4.

[0077] Figure 32 A graph showing the relationship between wavelength and relative visibility. Detailed implementation mode

[0078] Hereinafter, while referring to the accompanying drawings, the preferred implementation modes of the present invention will be described in detail. In addition, in this specification and the accompanying drawings, for structural elements having substantially the same functional structure, repeated descriptions are omitted by assigning the same reference numerals. In addition, for the sake of convenience of explanation, the states of the respective components disclosed in the following drawings are also schematically shown at scales and shapes different from the actual ones.

[0079] <1. Outline of wire grid polarizing element>

[0080] First, with reference to Figure 1 and Figure 2 etc., the outline of the wire grid polarizing element 1 according to an embodiment of the present invention will be described. Figure 1 A cross-sectional view schematically showing the wire grid polarizing element 1 according to this embodiment. Figure 2 A top view schematically showing the wire grid polarizing element 1 according to this embodiment.

[0081] 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 can 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 can be, for example, flat plate-shaped or curved plate-shaped. That is, the surface (the surface where light enters) of the wire grid polarizing element 1 can be a plane or a curved surface. 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 the example involved, and can have an arbitrary shape according to its use and function, etc.

[0082] In addition, the wire grid polarizing element of the present invention can be used, for example, as a polarizer that only transmits light vibrating in a specific direction, or can be used as a polarization beam splitter that separates incident light into first polarized light (S polarized light) and second polarized light (P polarized light). 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.

[0083] As Figure 1 and Figure 2As shown, the wire grid polarizing element 1 (hereinafter sometimes simply referred to as "polarizing element 1") includes a transparent substrate 10, a transparent grid structure 20, and an opaque functional film (such as a reflective film 30).

[0084] In addition, 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, the transmittance of this light is 70% or more. The wavelength range of visible light is, for example, 360 nm or more and 830 nm or less. The wavelength range of infrared light (infrared rays) is larger than the wavelength range of visible light, for example, 830 nm or more. From the viewpoint of the preferred wavelength range of visible light projected as a displayed image, the wavelength λ of the use band in the polarizing element 1 according to this embodiment is, for example, preferably 400 nm or more and 800 nm or less, and more preferably 420 nm or more and 680 nm or less. Since the polarizing element 1 according to this embodiment is formed of a material that is transparent to light in the use band, it does not cause adverse effects on the polarization characteristics, light transmittance, etc. of the polarizing element 1.

[0085] 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.

[0086] The grid structure 20 is made of a transparent organic material, such as an organic resin material such as a UV curable resin or a thermosetting resin with excellent heat resistance. The grid structure 20 has a concavo-convex structure for realizing the polarization function of the polarizing element 1. Specifically, the grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and a plurality of protruding strip portions 22 protruding from the base portion 21 in a lattice shape. The base portion 21 and the plurality of protruding strip portions 22 of the grid structure 20 are integrally formed of the same organic material.

[0087] The base portion 21 is a thin film having a predetermined thickness TB, and is laminated on the entire main surface of the substrate 10 ( Figure 1 and Figure 2 the XY plane shown). The thickness TB of the base portion 21 is preferably substantially the same thickness on the entire main surface of the substrate 10, but may not be exactly the same thickness, and may vary within a certain error with respect to the reference thickness of TB. For example, TB can vary within ±3 μm with respect to the reference thickness of 6 μm. In this way, the forming error when forming the base portion 21 based on imprinting or the like is allowed, and the thickness TB of the base portion 21 is determined.

[0088] A plurality of convex strip portions 22 are arranged on the base portion 21 at equal intervals in the X direction with a prescribed pitch P. Further, the pitch P is the formation interval of the plurality of convex strip portions 22 arranged in the X direction of the polarization element 1. The plurality of convex strip portions 22 are arranged in a lattice pattern so as to extend parallel to each other in the Y direction. A prescribed gap is formed between two adjacent convex strip portions 22 in the X direction. This gap serves as an incident light entry path. Each convex strip portion 22 is a wall-shaped convex portion that protrudes in a manner elongated in a prescribed direction ( Figure 1 and Figure 2 the Y direction shown). The height (H) of the plurality of convex strip portions 22 in the Z direction and the width (W T 、W B ) in the X direction are substantially the same as each other. The length direction (Y direction) of the convex strip portion 22 is the direction of the reflection axis of the polarization element 1, and the width direction (X direction) of the convex strip portion 22 is the direction of the transmission axis of the polarization element 1.

[0089] The functional film is a film for imparting a prescribed function to the grid structure 20 of the polarization element 1. The functional film is, for example, made of an opaque metal material and is provided so as to cover a part of the convex strip portion 22 of the grid structure 20. The functional film can be, for example, a reflection film 30 having a function of reflecting incident light incident on the polarization element 1, or an absorption film (not shown) having a function of absorbing the incident light, or a film having other functions. In the present embodiment, an example in which the functional film is the reflection film 30 will be described, but the functional film of the present invention is not limited to the example of the reflection film 30.

[0090] The reflection film 30 is, for example, a thin film made of a metal material (such as a metal or a metal oxide) such as aluminum or silver. The reflection film 30 is formed so as to cover at least the top of the convex strip portion 22. The reflection film 30 can be composed of a metal film that functions as a metal fine wire of a wire grid. The reflection film 30 has a function of reflecting incident light incident on the grid structure 20.

[0091] The convex strip portion 22 of the grid structure 20 and the reflection film 30 constitute the grid of the wire grid polarization element 1. The pitch P (i.e., the arrangement pitch of the grid) of the plurality of convex strip portions 22 in the X direction in the grid structure 20 is set to a pitch smaller than the wavelength λ of incident light (such as visible light) (for example, 1 / 2 or less). Thereby, the polarization element 1 can almost completely reflect the light (S-polarized light) in which the electric field vector component vibrates in the direction parallel to the reflection film 30 (conductive wire) extending in the Y direction (reflection axis direction: Y direction), and can almost completely transmit the light (P-polarized light) in which the electric field vector component vibrates in the direction perpendicular to the reflection film 30 (conductive wire) (transmission axis direction: X direction).

[0092] As described above, the wire grid polarizing element 1 according to the present embodiment realizes a polarization function by a combination of a grid structure body 20 having a fine concavo-convex structure and a functional film (for example, a reflective film 30) selectively applied to the ridge portions 22 of the grid structure body 20. Moreover, the substrate 10 of the wire grid polarizing element 1 is made of an inorganic material such as glass having extremely excellent heat resistance, and the grid structure body 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 polarizing element in which an organic material and an inorganic material are combined. Therefore, heat can be effectively released from the grid structure body 20 having a small thermal resistance R [m 2 ·K / W] to the substrate 10, so that the heat dissipation property is excellent. Therefore, the hybrid wire grid polarizing element 1 according to the present embodiment has excellent heat resistance and heat dissipation property as compared with a conventional film type polarizing element made only of an organic material (heat resistance: about 100°C), and has heat resistance in a high temperature environment of up to about 200°C, for example. Thus, excellent polarization characteristics can be achieved, and a good heat dissipation effect can be maintained.

[0093] Moreover, the wire grid polarizing element 1 according to the present embodiment may also include a protective film 40 covering the surface of the grid structure body 20 (see Figure 7 , Figure 8 ). The protective film 40 is made of an inorganic material, for example, a dielectric material such as SiO2. The protective film 40 may also be laminated on the entire surface of the wire grid polarizing element 1 so as to cover the entire surfaces of the base portion 21, the ridge portions 22, and the reflective film 30 of the grid structure body 20 (see Figure 7 ). By providing the protective film 40, an advantageous effect of further reducing the thermal resistance R of the polarizing element 1 can be obtained, so that excellent polarization characteristics can be achieved and a better heat dissipation effect can be maintained.

[0094] In addition, as described above, the grid structure body 20 in which the base portion 21 and the ridge portions 22 are integrally formed can be manufactured by a printing technique such as nanoimprinting, so that a fine concavo-convex structure can be realized by a simple manufacturing process. Therefore, as compared with the case of manufacturing using a photolithography technique and an etching technique, the cost and labor required for manufacturing the grid structure body 20 can be reduced. Thus, the hybrid polarizing element 1 according to the present embodiment has the advantages of being able to greatly reduce the manufacturing cost and making the unit price of the wire grid polarizing element 1 inexpensive as compared with a conventional polarizing element made only of an inorganic material.

[0095] On the other hand, since most of the existing film-type organic polarizing plates use organic materials, the thicknesses of the substrate (base film), the double-sided adhesive (OCA: Optically Clear Adhesive), and the grating structure are increased. Therefore, it is considered that the heat dissipation and heat resistance are poorer than those of the hybrid polarizing element 1 according to the present embodiment.

[0096] In addition, in the wire grid polarizing element 1 according to the present embodiment, the grating formed by the ridge portions 22 of the grating structure 20 and the reflective film 30 has Figure 1 a special tree shape as shown in etc. (details will be described later). Thus, even when light obliquely enters the polarizing element 1 at a wide range of large incident angles θ (for example, 30 to 60°), it is possible to suppress the transmittance of the second polarized light (P-polarized light) transmitted through the polarizing element 1 (i.e., the transmittance of the transmission axis Tp) from decreasing depending on the incident angle θ of the obliquely incident light. Therefore, it is possible to maintain the product of the reflectance of the first polarized light (S-polarized light) reflected by the wire grid polarizing element 1 (i.e., the reflectance of the reflection axis Rs) and the transmittance of the transmission axis Tp (Tp×Rs) at a high value of, for example, 70% or more. Therefore, the polarization separation characteristics represented by Tp×Rs of the polarizing element 1 according to the present embodiment are excellent, and it is possible to polarize the obliquely incident light and appropriately separate the S-polarized light (reflected light) and the 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.

[0097] As described above, the wire grid polarizing element 1 according to the present embodiment has excellent heat resistance and heat dissipation, the manufacturing cost can also be reduced, and the transmittance and polarization separation characteristics for obliquely incident light with a large incident angle θ in a wide range are also excellent. Thus, the wire grid polarizing element 1 according to the present embodiment can be suitably used as various components of various products. For example, the polarizing element 1 can be applied to a polarization beam splitter installed in a smart display. In addition, the polarizing element 1 can also be applied to a polarizing element for coping with heat from sunlight, a polarizing element for coping with heat from an LED light source, a polarization mirror, etc. installed in a head-up display (HUD). Moreover, the polarizing element 1 can also be applied to a polarization 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).

[0098] <2. Structural elements of the wire grid polarizing element>

[0099] Next, with reference to Figure 1 and Figure 2Etc. will be used to explain in detail the structural elements of the wire grid polarizing element 1 according to this embodiment.

[0100] <2.1. Substrate>

[0101] As Figure 1 shown, the wire grid polarizing element 1 according to this embodiment includes a transparent substrate 10. The substrate 10 is transparent and made of an inorganic material having a certain degree of strength.

[0102] As the material of the substrate 10, from the viewpoint of obtaining more excellent heat dissipation and heat resistance, for example, various inorganic materials such as various glasses, quartz, crystal, sapphire, etc. are preferred, and an inorganic material having a thermal conductivity of 1.0 W / m·K or more is more preferred, and an inorganic material having a thermal conductivity of 8.0 W / m·K or more is further preferred.

[0103] In addition, 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, etc. For example, it can be configured to have a plate shape or a curved surface. In addition, 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. Moreover, the thickness TS of the substrate 10 is not particularly limited either, and for example, it can be in the range of 0.02 to 10.0 mm.

[0104] <2.2. Grid structure>

[0105] As Figure 1 and Figure 2 shown, the polarizing element 1 according to this embodiment includes a grid structure 20 having the above-mentioned base portion 21 and lattice-shaped rib portions 22 on the substrate 10. By providing a reflection film 30 described later on the rib portions 22, the grid structure 20 can obtain the desired polarization characteristics.

[0106] When light is incident on the polarizing element 1 from the surface side where the grid structure 20 is formed, a part of the incident light is reflected by the reflection film 30. Among the light incident on the reflection film 30, the light having an electric field component in the direction orthogonal to the length direction of the rib portion 22 (i.e., the extending direction of the rib portion 22 = the reflection axis direction: Y direction) (i.e., the width direction of the rib portion 22 = the transmission axis direction: X direction) passes through the polarizing element 1 with a high transmittance. On the other hand, among the light incident on the reflection film 30, the light having an electric field component in the direction parallel to the length direction of the rib portion 22 (i.e., the extending direction of the rib portion 22 = the reflection axis direction: Y direction) is mostly reflected by the reflection film 30. Therefore, in this embodiment, by providing the grid structure 20 partially covered by the reflection film 30, single polarized light can be generated. In addition, the same polarization effect can also be obtained for the light incident from the back side of the substrate 10.

[0107] The grid structure 20 is asFigure 1 As shown, it has a base 21. The base 21 is a thin film provided along the surface of the substrate 10, and is a portion for supporting the ridge portion 22. When the concave-convex structure (ridge portion 22) of the grid structure 20 is formed by nanoimprinting or the like, the base 21 is inevitably formed. The base 21 and the ridge portion 22 are integrally formed of the same material. In addition, since the grid structure 20 has the base 21, the strength of the ridge portion 22 can be improved compared to the case where the ridge portion 22 is directly formed on the substrate 10. Therefore, the durability of the grid structure 20 can be improved. Moreover, since the base 21 is in contact with the substrate 10 over the entire surface, the peeling resistance of the grid structure 20 can be improved.

[0108] The thickness TB of the base portion 21 is not particularly limited, but is preferably 1 nm or greater, and more preferably 10 nm or greater, from the perspective of more reliably supporting the ridges 22 and facilitating imprint molding. Furthermore, from the perspective 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.

[0109] Furthermore, according to the polarizing element 1 of this embodiment, since the base portion 21 and the plurality of ridges 22 of the grid structure 20 are formed directly on the substrate 10, the thickness TB of the base portion 21 can be reduced. To improve heat dissipation from the grid structure 20 to the substrate 10, it is preferable to reduce the temperature difference ΔT [°C] between the front and back surfaces of the base portion 21 by reducing the thickness TB of the base portion 21. The temperature difference ΔT is the difference between the temperature T1 [°C] of the outermost surface of the base portion 21 (the base of the plurality of ridges 22) and the temperature T2 [°C] of the base portion 21 at the interface between the base portion 21 and the substrate 10 (ΔT = T1 - T2).

[0110] Therefore, the thickness TB of the base portion 21 is preferably 0.15 mm or less. Thus, the heat of the grid structure 20 composed of an organic material can be quickly transferred to the substrate 10 composed of an inorganic material, and effectively released from the substrate 10 to the outside of the polarizing element 1 for heat dissipation, so that the temperature difference ΔT can be, for example, below 32°C. Moreover, the thickness TB of the base portion 21 is more preferably 0.09 mm or less, thereby making the temperature difference ΔT, for example, below 20°C. Moreover, the thickness TB of the base portion 21 is more preferably 0.045 mm or less, thereby making the temperature difference ΔT, for example, below 10°C. Moreover, the thickness TB of the base portion 21 is particularly preferably 0.02 mm or less, thereby making the temperature difference ΔT, for example, below 5°C. In this way, by thinning the thickness TB of the base portion 21, the heat dissipation from the grid structure 20 to the outside across the substrate 10 can be improved, so the heat dissipation and heat resistance of the polarizing element 1 can be improved.

[0111] Furthermore, as shown in Figure 1 and Figure 2 , the grid structure 20 has a plurality of rib portions 22 protruding from the base portion 21. The rib portions 22 extend in the length direction along the reflection axis direction (Y direction) of the polarization element 1 according to the present embodiment. The plurality of rib 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-shaped concavo-convex structure.

[0112] Here, as shown in Figure 1 , in a longitudinal section (XZ section) orthogonal to the reflection axis direction (Y direction) of the polarization element 1, it is necessary that the pitch P in the transmission axis direction (X direction) of the rib portion 22 is shorter than the wavelength of light in the used wavelength band. The reason is to obtain the above-described polarization light effect. More specifically, from the viewpoint of coexistence of easiness of manufacturing and polarization characteristics of the rib portion 22, the pitch P of the rib portion 22 is preferably 50 to 300 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm.

[0113] In addition, as shown in Figure 1 and Figure 2 , the width W of the bottom of the rib portion 22 in the above-described longitudinal section (XZ section) B is not particularly limited, but from the viewpoint of coexistence of easiness of manufacturing and polarization characteristics, it is preferably about 10 to 150 nm, more preferably about 10 to 100 nm. In addition, the width W of the top of the rib portion 22 T is not particularly limited, but from the viewpoint of coexistence of easiness of manufacturing and polarization characteristics, it is preferably about 5 to 60 nm, more preferably about 10 to 30 nm.

[0114] In addition, the width W of the bottom of the rib 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 section) orthogonal to the absorption axis direction or the reflection axis direction of the polarization element 1 using a scanning electron microscope or a transmission electron microscope, for any four rib portions 22, the width of the rib portion 22 at the height position 20% above the height H from the bottom of the rib portion 22 to the top of the rib portion 22 is measured, and their arithmetic mean value can be used as the width W of the bottom of the rib portion 22 B . In addition, for these arbitrary four rib portions 22, the width of the rib portion 22 at the height position 20% below the height H from the front end 22a of the rib portion 22 to the top of the rib portion 22 is measured, and their arithmetic mean value can be used as the width W of the top of the rib portion 22 T .

[0115] In addition, asFigure 1 As shown, the height H of the rib portion 22 in the above longitudinal section (XZ section) is not particularly limited. However, from the viewpoints of ease of manufacturing and coexistence of polarization characteristics, it is preferably on the order of 50 to 350 nm, and more preferably on the order of 100 to 300 nm. In addition, the height H of the rib portion 22 can be measured by observing with a scanning electron microscope or a transmission electron microscope. For example, by observing a section orthogonal to the absorption axis direction or the reflection axis direction of the polarization element 1 using a scanning electron microscope or a transmission electron microscope, for any four rib portions 22, the height of the rib portion 22 at the center position in the width direction of the rib portion 22 is measured, and their arithmetic mean value can be used as the height H of the rib portion 22.

[0116] In order to obtain good polarization separation characteristics for obliquely incident light, the shape of the rib portion 22 of the grating structure 20 is preferably a tapered shape. Here, the tapered shape means that the width W (the width in the X direction in the XZ section) of the rib 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 rib portion 22 gradually narrows from the bottom to the top of the rib portion 22. Therefore, when the rib portion 22 has a tapered shape, the width W at the top of the rib portion 22 T is smaller than the width W at the bottom of the rib portion 22 B (W T <W B ).

[0117] Figure 3 Shows a specific example of the tapered shape of the rib portion 22 according to the present embodiment. As Figure 3 shown, as long as the cross-sectional shape of the rib portion 22 in the above longitudinal section (XZ section) is the above tapered shape, it can be various shapes such as a trapezoid, a triangle, a bell shape, an ellipse, or a wedge shape with a circular shape in which the width W gradually narrows as it moves away from the base portion 21. For example, Figure 3 as shown, the cross-sectional shape of the rib portion 22A 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 a circular shape at the top and bottom. Thus, since the rib portion 22 has a tapered shape, it is easy to form a reflective film 30 covering the front end 22a and a part of the side surface 22b of the rib portion 22, and polarization characteristics can be imparted to the polarization element 1, and this tapered shape can also be formed by nanoimprinting, so it is also advantageous in terms of ease of manufacturing.

[0118] In addition, the rib portion 22 has a tapered shape such as a gradually widening shape, so that the refractive index of the grating structure 20 gradually changes. Therefore, similarly to the moth-eye structure, an antireflection effect of incident light caused by the physical change in the refractive index of the grating structure 20 can be obtained. As a result, it is also possible to expect an effect of reducing the reflectance on the surface of the rib portion 22 of the grating structure 20 and improving the transmittance of the grating structure 20.

[0119] In addition, Figure 4 A specific example of the shape of the concave portion 24 formed between the adjacent rib portions 22, 22 is shown. The concave portion 24 is a groove extending in the longitudinal direction (Y direction) of the rib portion 22. As Figure 4 shown, the cross-sectional shape of the concave portion 24 in the above longitudinal section (XZ section) can be various shapes as long as the width narrows toward the bottom of the concave portion 24. For example, Figure 4 the cross-sectional shape of the concave portion 24A shown is trapezoidal (gradually widening shape), the cross-sectional shape of the concave portion 24B is triangular (V-shaped), the cross-sectional shape of the concave portion 24C is a substantially rectangular shape with a flat bottom, and the cross-sectional shape of the concave portion 24D is a U-shaped with a rounded bottom. As the shape of these concave portions 24, the optimum shape can be appropriately selected in consideration of productivity such as mold release properties during nanoimprint formation.

[0120] In addition, the material constituting the grating 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 aspect of ensuring excellent transparency and ease of manufacture, various thermosetting resins, various ultraviolet curable resins, etc. are preferably used as the material of the grating structure 20.

[0121] Moreover, from the aspects of ease of manufacture and manufacturing cost, the material constituting the grating structure 20 is preferably a material different from that of the substrate 10. In addition, when the materials of the grating structure 20 and the substrate 10 are different, their refractive indices are different. Therefore, when it affects the refractive index of the entire polarization element 1, a refractive index adjustment layer can also be appropriately provided between the grating structure 20 and the substrate 10.

[0122] For example, as the material for forming the grid structure 20, a curable resin such as an epoxy polymerizable compound or an acrylic polymerizable compound can be used. 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 polyurethane, naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolak type epoxy resins, stilbene type epoxy resins, triphenylmethane type epoxy resins, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, and their prepolymers.

[0123] 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.

[0124] Examples of the "monofunctional monomer" include carboxylic acids (such as acrylic acid), hydroxyl groups (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate), alkyl or alicyclic monomers (isobutyl acrylate, tert-butyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, cyclohexyl acrylate), and other functional monomers (2-methoxyethyl acrylate, methoxyethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl acrylamide, N,N-dimethylacrylamide, acryloyl morphine, 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.

[0125] Examples of the "bifunctional monomer" include tris(propylene glycol) diacrylate, trimethylolpropane-diallyl ether, polyurethane diacrylate, etc.

[0126] As the "polyfunctional monomer", for example, trimethylolpropane triacrylate, dipentaerythritol penta- and hexaacrylate, bis-trimethylolpropane tetraacrylate, etc. can be cited.

[0127] As examples other than the acrylic polymerizable compounds listed above, acrylic morpholine, glycerol acrylate, polyether-based acrylate, N-vinylformamide, N-vinylcaprolactam, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, polyethylene glycol acrylate, EO-modified trimethylolpropane triacrylate, EO-modified bisphenol A diacrylate, aliphatic polyurethane oligomer, polyester oligomer, etc. can be cited.

[0128] In addition, as the curing initiator of the above-mentioned cured resin, for example, a thermal curing initiator, a photo-curing initiator, etc. can be cited. The curing initiator can also be a substance that is cured by some energy ray (such as an electron beam) other than heat and light. When the curing initiator is a thermal curing initiator, the cured resin is a thermosetting resin, and when the curing initiator is a photo-curing initiator, the cured resin is a photo-curing resin.

[0129] Among them, as the curing initiator, an ultraviolet curing initiator is preferably used. The ultraviolet curing initiator is a kind of photo-curing initiator. As the ultraviolet curing initiator, for example, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, etc. can be cited. Therefore, the cured resin is preferably an ultraviolet curing resin. In addition, from the viewpoint of transparency, the cured resin is preferably an ultraviolet curable acrylic resin.

[0130] In addition, the method for forming the grid structure 20 is not particularly limited as long as it can form the above-mentioned base portion 21 and rib portion 22. For example, an uneven formation method based on photolithography, imprinting, etc. can be used. Among them, from the viewpoints of being able to form an uneven pattern in a short time and easily and being able to reliably form the base portion 21, it is preferable that the base portion 21 and rib portion 22 of the grid structure 20 are formed by imprinting.

[0131] In the case of forming the base portion 21 and rib portion 22 of the grid structure 20 by nanoimprinting, for example, after coating a material (grid structure material) for forming the grid structure 20 on the substrate 10, a master disk having unevenness is pressed against the grid structure material, and in this state, ultraviolet rays are irradiated or heat is applied, so that the grid structure material can be cured. Thereby, the grid structure 20 having the base portion 21 and rib portion 22 can be formed.

[0132] <2.3. Reflective film (functional film)>

[0133] The polarization element 1 according to this embodiment is as Figure 1 and Figure 2 shown, and includes a reflective film 30 formed on the ridge portion 22 of the grid structure 20.

[0134] As Figure 1 shown, the reflective film 30 is formed so as to cover the front end 22a of the ridge portion 22 of the grid structure 20 and a part of the side surface 22b. And, as Figure 1 shown, the reflective film 30 is formed so as to extend along the length direction (Y direction) of the ridge portion 22 of the grid structure 20. Thus, the reflective film 30 can reflect the light having an electric field component in the direction (reflection axis direction: Y direction) parallel to the length direction of the ridge portion 22 among the light incident on the polarization element 1.

[0135] The material constituting the reflective film 30 is not particularly limited as long as it is a material having reflectivity for light in the use wavelength band. For example, metal element monomers 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 cited.

[0136] In addition, the reflective film 30 may be a single-layer film made of the above metals, or may be a multilayer film made of multiple metal films. In addition, as long as the reflective film 30 has a reflection function, other layers such as a dielectric film may be included as needed. 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. In addition, the refractive index of the dielectric film is preferably greater than 1.0 and 2.5 or less. In addition, since the optical characteristics of the reflective film 30 are also affected by the refractive index of the surroundings, the polarization characteristics can also be controlled by the material of the dielectric film.

[0137] <2.4. Special shapes of the ridge portion and the reflective film>

[0138] Here, the special shapes of the ridge portion 22 of the grid structure 20 and the reflective film 30 in the polarization element 1 according to this embodiment will be described in detail.

[0139] In the polarization element 1 according to this embodiment, as Figure 1 and Figure 5 shown, the reflective film 30 is formed so as to cover the front end 22a of the ridge portion 22 of the grid structure 20 and the upper side of at least one side surface 22b, and does not cover the lower side of the both side surfaces 22b and the base portion 21 of the ridge portion 22. In addition, although Figure 1 and Figure 5In the example, the reflective film 30 covers the upper sides of both side surfaces 22b of the rib portion 22, but it may also cover only the upper side of one side surface 22b of the rib portion 22.

[0140] Here, the state where "the reflective film 30 covers the front end 22a of the rib portion 22 of the grid structure 20 and the upper sides of at least one side surface 22b" means, for example Figure 1 and Figure 5 As shown, the "front end 22a of the rib portion 22" and "the upper sides of the side surface 22b of the front end 22a of the rib portion 22 and the base portion 21" are continuously covered by the reflective film 30, and 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 surface 22b of the rib portion 22 (all side surfaces 22b from the front end 22a of the rib portion 22 to the base portion 21).

[0141] Moreover, the surface of the reflective film 30 that covers the front end 22a of the rib portion 22 and the upper sides of at least one side surface 22b (hereinafter sometimes also referred to as the "top of the rib portion 22") has a shape that is circularly curved (for example, a longitudinally long, substantially elliptical shape) and bulges in the width direction (X direction) of the rib portion 22. Thus, the surface of the reflective film 30 becomes a smoothly curved surface shape without having angular corner portions or stepped portions. The maximum width W of the reflective film 30 that covers the top of the rib portion 22 in this way MAX is the width W of the bottom of the rib portion 22 B The above. Moreover, W MAX is preferably greater than W B .

[0142] Here, the maximum width W of the reflective film 30 that covers 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 Figure 1 and Figure 5 shown, etc., the horizontal widths (widths in the X direction) of the outermost surfaces on both sides of the reflective film 30 that covers 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 of 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 (when the incident angle θ = 0°), W MAX corresponds to the effective grid width of the reflective film 30.

[0143] The width W of the bottom of the rib portion 22B As Figure 1 and Figure 3 shown, it is the horizontal width (width in the X direction) of the rib portion 22 at the height position 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 of the bottom of the rib portion 22 B is the horizontal width of the rib portion 22 at the position of the height of 0.2×H upward from the upper surface of the base portion 21.

[0144] In addition, the width W of the top of the rib portion 22 T As Figure 1 and Figure 3 shown, it is the horizontal width (width in the X direction) of the rib portion 22 at the height position 20% below the height H of the rib portion 22 from the front end 22a of the rib portion 22. That is, the width W of the top of the rib portion 22 T is the horizontal width of the rib portion 22 at the position of the height of 0.8×H upward from the upper surface of the base portion 21 (that is, at the position of the height of 0.2×H downward from the front end 22a of the rib portion 22).

[0145] In addition, in the following description, the convex structure formed by combining the rib portion 22 and the reflective film 30 is sometimes referred to as a "grid", and the height of the convex structure (i.e., the grid) formed by combining the rib portion 22 and the reflective film 30 is sometimes referred to as the "grid height". In addition, the maximum width W of the reflective film 30 covering the rib portion 22 is sometimes MAX referred to as the "grid maximum width W MAX ", the width W of the bottom of the rib portion 22 is sometimes B referred to as the "grid bottom width W B ", and the width W of the top of the rib portion 22 is sometimes T referred to as the "width of the top of the rib portion W T ", and the width at the central position in the height direction of the rib portion 22 is referred to as the "central width of the rib portion".

[0146] Thus, in the present embodiment, as the width W of the bottom of the rib portion 22 B , the horizontal width of the rib portion 22 from the lowermost part (bottom) to the height position 20% above is used, and as the width W of the top of the rib portion 22 T , the horizontal width of the rib portion 22 from the front end 22a to the height position 20% below is used. The reason is that since the width of the lowermost part of the rib portion 22 at the upper surface of the base portion 21 and the width of the front end 22a of the rib portion 22 deviate greatly due to the manufacturing conditions of the grid structure 20 and the like, it is difficult to accurately measure these widths.

[0147] As described above, in the grid structure 20 according to the present embodiment, a convex strip portion 22 having a head-thin shape and a reflective film 30 covering only the front end 22a and the upper side of the side surface 22b of the convex strip portion 22 are formed. Further, the lower side of the side surface 22b of the convex strip portion 22 is not covered by the reflective film 30 and is open.

[0148] As a result, the cross-sectional shape of the convex strip portion 22 covered by the curved reflective film 30 (that is, the cross-sectional shape of the grid) has a special cross-sectional shape as follows. That is, as Figure 1 and Figure 5 shown, 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 from the central portion of the convex strip portion 22 exposed without being covered by the reflective film 30 to the bottom side portion (for example, the width W of the bottom of the exposed convex strip portion 22 B ) is small. Further, the cross-sectional shape of the entire convex structure formed by the convex strip portion 22 and the reflective film 30 (that is, the "grid") has a constriction portion that contracts inward and becomes narrower in 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 exemplified by the shape of a tree. Specifically, the part of the leaves of a round, large, and wide tree corresponds to the part of the reflective film 30 covering the top of the convex strip portion 22, the part of the trunk of the tree corresponds to the lower side portion of the convex strip portion 22 not covered by the reflective film 30, and the part 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 formed by 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".

[0149] The grid of the grid structure 20 of the polarization element 1 according to the present embodiment has the above-described special tree shape. Thus, for example, as Figure 31 shown, when incident light is incident obliquely on the polarization element 1, the effective grid width W A becomes smaller and the gap width W G becomes larger. 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 the reflective films 30, 30 of two adjacent grids, and is the width of the gap in the direction perpendicular to the obliquely incident light. The larger the effective grid width W A , the more easily the obliquely incident light is reflected by the reflective film 30 and the more difficult it is to reach the transparent convex strip portion 22 and the base portion 21. Therefore, in the polarization element 1, the transmittance of the obliquely incident light decreases. On the other hand, the gap width W GThe larger it is, the easier it is for the obliquely incident light to pass through between two adjacent reflective films 30, 30 and reach the transparent rib portions 22 and the base portions 21. Thereby, the transmittance with respect to the obliquely incident light can be improved.

[0150] Therefore, since the grid of the polarization element 1 according to the present embodiment has the above-described special tree shape, the gap width W for the obliquely incident light G becomes larger, and the obliquely incident light easily passes through the gaps between the circular reflective films 30, 30 and reaches and passes through the transparent grid structure 20. Therefore, the transmittance Tp of the transmission axis of the obliquely incident light is high, so the transmittance and polarization separation characteristics (Tp×Rs characteristics) for the obliquely incident light are very excellent. Moreover, it is possible to balance the reflection function of the obliquely incident light realized by the reflective film 30 and the transmission function of the obliquely incident light realized by the grid structure 20, and the polarization separation characteristics for the obliquely incident light can be further improved.

[0151] <2.5. Method of forming reflective film and specific example>

[0152] Here, with reference to Figure 5 the method of forming the reflective film 30 will be described.

[0153] As a method of forming the reflective film 30 in such a manner that the reflective film 30 covers the front end 22a and a part of both side surfaces 22b of the rib portion 22 of the grid structure 20, as Figure 5 shown, preferably, sputtering or evaporation is alternately performed on the rib portion 22 of the grid structure 20 obliquely (film-forming incident angle ) to form the reflective film 30. Thereby, the reflective film 30 can be formed to cover the upper side of the front end 22a and both side surfaces 22b of the rib portion 22. In addition, the film-forming incident angle for forming the reflective film 30 by sputtering or evaporation is not particularly limited. For example, it can be about 5 to 70° with respect to the surface of the substrate 10.

[0154] 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 evaporation. Thereby, it is possible to easily change the film formation conditions, materials, and film thickness of the reflective film 30. In addition, even when the reflective film 30 is composed of multiple layers, it can be easily dealt with. Therefore, by combining metals, semiconductors, and dielectrics, film design using interference effects can be performed. When forming the reflective film 30 obtained by etching as in the prior art, there is no need to consider the material composition that can be etched, etc. Thus, it is also easy to adjust the reflectivity of the polarized light wave parallel to the grid structure 20 and the transmittance (transmission amount) of the polarized light in the direction perpendicular to the grid. In addition, after forming the grid structure 20, the reflective film 30 is formed, so that equipment such as a vacuum dry etching device is not required, and safety devices such as gases and decontamination devices that cooperate with complex processes and etching materials are not required. Thereby, the operating costs such as equipment investment and maintenance can be reduced, and a cost advantage can also be obtained.

[0155] In addition, Figure 5 The thickness Dt of the reflective film 30 covering the front end 22a of the covering rib portion 22 and the thickness Ds of the reflective film 30 covering the side surface 22b of the covering rib portion 22 are not particularly limited and can be appropriately changed according to the shape of the rib portion 22 of the grid structure 20, the performance required for the reflective film 30, etc. For example, from the viewpoint of obtaining more excellent reflective performance, the thicknesses Dt and Ds of the reflective film 30 are preferably 2 to 200 nm, more preferably 5 to 150 nm, further preferably 10 to 100 nm, and particularly preferably 15 to 80 nm. In addition, as the thickness Ds of the reflective film 30 is as Figure 5 shown, it is the thickness of the thickest part among the reflective films 30 covering the side surface 22b of the rib portion 22.

[0156] In addition, the shape of the reflective film 30 is not particularly limited as long as it can form the above-mentioned special tree shape, and can be appropriately selected according to the conditions of the device used to form the reflective film 30 and the performance required for the reflective film 30.

[0157] Figure 6 It is a cross-sectional view schematically showing a specific example of the shape of the reflective film 30. As Figure 6 shown, as long as the reflective film 30 is bent in a manner that wraps the top of the rib portion 22 (the front end 22a and the upper side of the side surface 22b), it can have various shapes.

[0158] For example, Figure 6The reflective film 30A shown covers the tops of the rib portions 22A, 22B, and 22C with various cross-sectional shapes in a round manner and has a substantially oval shape that bulges significantly in the width direction of the rib portion 22. In addition, the reflective film 30B has a curved shape that covers the top of the substantially wedge-shaped rib portion 22D. In addition, the reflective film 30C has a curved shape that covers the top of the trapezoidal rib portion 22A. The coverage rate Rc of one side surface 22b of the rib portion 22 covered by these reflective films 30B and 30C is substantially the same as that of the other side surface 22b.

[0159] In addition, although the reflective film 30D covers the top of the substantially wedge-shaped rib portion 22D, it is biased toward one side surface 22b ( Figure 6 the left side surface 22b shown) of the rib portion 22. Specifically, the reflective film 30D covers a large range of the left side surface 22b of the rib portion 22, and its coverage rate Rc is about 80%. On the other hand, the reflective film 30D only covers a small range of the upper part of the right side surface 22b, and its coverage rate Rc is about 25%. Thus, there can also be a difference in the coverage rate Rc achieved by the reflective film 30D between one side surface 22b and the other side surface 22b of the rib portion 22.

[0160] <2.6. Preferred range of the coverage rate Rc of the rib portion covered by the reflective film>

[0161] Next, the preferred range of the coverage rate Rc of the side surface 22b of the rib portion 22 covered by the reflective film 30 according to the present embodiment will be described.

[0162] 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 rib portion 22 covered by the reflective film 30 to the height (H) of the rib portion 22. The coverage rate Rc is represented by the following formula (1). Figure 1 and Figure 5 shown. The coverage rate Rc is represented by the following formula (1).

[0163] Rc [%] = (Hx / H) × 100…(1)

[0164] H: The height of the rib portion 22 in the Z direction

[0165] Hx: The height in the Z direction of the portion of the side surface 22b of the rib portion 22 covered by the reflective film 30

[0166] In addition, the opening rate Rr is, relative to Figure 1 and Figure 5The ratio of the height (H - Hx) of the portion of the side surface 22b of the rib portion 22 that is not covered by the reflective film 30 to the height (H) of the rib portion 22 shown. The opening rate Rr is represented by the following formula (2).

[0167] Rr [%] = ((H - Hx) / H) × 100…(2)

[0168] According to the above definition, Rr = 100 - Rc. Thus, when the coverage rate Rc of the side surface 22b of the rib portion 22 covered 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 covered by the reflective film 30 is 20% or more and 75% or less.

[0169] As described above, in the polarization element 1 according to the present embodiment, the coverage rate Rc of the side surface 22b of the rib portion 22 covered by the reflective film 30 is preferably 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 front end 22a of the rib portion 22 and the upper sides of both side surfaces 22b, and the lower sides of both side surfaces 22b are not covered and are open. And the coverage rate Rc is preferably 25% or more and 80% or less, more preferably 30% or more and 70% or less, and still more preferably 40% or more and 50% or less.

[0170] With the related structure, the polarization 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 separating obliquely incident light into S-polarized light (reflected light) and P-polarized light (transmitted light) through the polarization element 1, regardless of the incident angle θ of the obliquely incident light, the transmittance Tp of the P-polarized light (transmitted light) passing through the polarization element 1 can be maintained at a high value. In addition, by making the coverage rate Rc 25% or more and 80% or less, the ratio of the transmittance axis transmittance (Tp) to the transmittance axis reflectance (Ts), that is, the contrast (CR = Tp / Ts), can be maintained at a good level, and the reflection effect achieved by the above-mentioned reflective film 30 can be more reliably 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.

[0171] In contrast, as a comparative example, in the case where the reflective film 30 is formed to cover only the front end 22a of the rib portion 22 of the grid structure 20, or in the case where it is formed to cover the front end 22a of the rib portion 22 and the entire one side surface 22b (for example, refer to Figure 18), depending on the incident angle θ of the obliquely incident light, the deviation of the transmittance Tp becomes larger, and it is considered that sufficient transmittance cannot be obtained even for obliquely incident light with a large incident angle θ. In addition, as a comparative example, when the reflective film 30 covers the entire front end 22a and both side surfaces 22b of the rib portion 22 of the grating structure 20 (when the coverage rate Rc is 100%), when the incident angle θ of the obliquely incident light becomes larger, the transmittance drops significantly.

[0172] Therefore, from the viewpoint of improving the transmittance and polarization separation characteristics of the transmitted light without depending on the incident angle θ of the obliquely incident light, it is preferable that, as in the polarization element 1 according to the present embodiment, the reflective film 30 covers the front end 22a and at least a part of one side surface 22b (the upper side of the side surface 22b) of the rib portion 22.

[0173] Moreover, from the viewpoint of the Tp×Rs characteristics required for a polarization beam splitter (PBS), in the polarization element 1 according to the present embodiment, the coverage rate Rc of the side surface 22b of the rib portion 22 covered by the reflective film 30 is preferably 25% or more and 80% or less (for example, refer to Figure 27 ).

[0174] When the coverage rate Rc is less than 25%, the transmittance Tp of the P-polarized light transmitted through the transmission axis of the polarization element 1 decreases, and a deviation occurs in the transmittance Tp depending on the incident angle θ, and a sufficiently high Tp×Rs value cannot be obtained. Therefore, sufficient transmittance of the transmitted light and polarization separation characteristics represented by Tp×Rs cannot be obtained for obliquely incident light with a large incident angle θ. On the other hand, when the coverage rate Rc exceeds 80% (for example, refer to Figure 20 ), similar to the case where the entire front end 22a and both side surfaces 22b of the rib portion 22 of the grating structure 20 are covered, the larger the incident angle θ of the obliquely incident light (for example, 45 to 60°), the more the transmittance Tp of the transmission axis decreases, so that the deviation in the transmittance Tp becomes larger depending on the incident angle θ.

[0175] Therefore, the coverage rate Rc of the side surface 22b of the rib portion 22 covered by the reflective film 30 is preferably 25% or more and 80% or less (for example, refer to Figure 27) Thus, when light is incident obliquely, for example, at an incident angle θ of 45°, on the polarization element 1, the transmittance Tp of the second polarized light (P-polarized light) transmitted through the polarization element 1 can be 75% or more. As a result, Tp×Rs can be 70% or more. Thus, even when wide-range obliquely incident light is incident at a large incident angle θ, the transmittance of the second polarized light (P-polarized light) in the transmission axis direction of the polarization element 1 can be improved, the polarization separation characteristics of the polarization element 1 can be improved, and the obliquely incident light can be appropriately separated into the first polarized light (S-polarized light) and the second polarized light (P-polarized light) by the polarization element 1.

[0176] From the same viewpoint, the coverage ratio Rc is more preferably 30% or more and 70% or less (that is, the opening ratio Rr is 30% or more and 70% or less). Thus, in the case of the above-described oblique incidence conditions, a high transmittance Tp of 80% or more can be obtained, and a high Tp×Rs of 72% or more can be obtained. Further, the coverage ratio Rc is more preferably 30% or more and 60% or less (that is, the opening ratio Rr is 40% or more and 70% or less). Thus, in the case of the above-described oblique incidence conditions, a high transmittance Tp of 83% or more can be obtained, and a high Tp×Rs of 75% or more can be obtained. Moreover, the coverage ratio Rc is still more preferably 40% or more and 50% or less (that is, the opening ratio Rr is 50% or more and 60% or less). Thus, in the case of the above-described oblique incidence conditions, 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.

[0177] In addition, regarding the reflectance Rs of the reflection axis, the coverage ratio Rc is preferably 20% or more. Thus, in the case of the above-described oblique incidence conditions, a high reflectance Rs of 85% or more can be obtained.

[0178] In addition, regarding the contrast ratio CR of the transmitted light (CR = Tp / Ts), as long as the coverage ratio Rc is 20% or more, a sufficient contrast ratio CR can be obtained. The higher the coverage ratio Rc, the higher the contrast ratio CR obtained.

[0179] <2.7. Preferred range of Tp×Rs>

[0180] Next, the preferred range of "Tp×Rs", which is an index representing the polarization separation characteristics of the wire grid polarization element 1 according to the present embodiment, will be described.

[0181] Tp×Rs [%] represents the product of the transmittance (Tp) of the transmission axis and the reflectance (Rs) in percentage. This Tp×Rs becomes an index representing the polarization separation characteristics of the wire grid polarization element 1.

[0182] Tp×Rs[%]=(Tp[%] / 100)×(Rs[%] / 100)×100

[0183] In addition, as described above, the transmittance of the transmission axis (Tp) is the transmittance of the second polarized light (P-polarized light) having an electric field component parallel to the transmission axis (X direction) of the polarization element 1. The reflectance of the reflection axis (Rs) is the reflectance of the first polarized light (S-polarized light) having an electric field component parallel to the reflection axis (Y direction) of the polarization element 1.

[0184] When using the wire grid polarizing element 1 according to the present embodiment as a polarization beam splitter to separate incident light into S-polarized light and P-polarized light (refer to Figures 15 - 17 ), the polarization element 1 is disposed at an angle (e.g., 45°) with respect to the incident light from the light source. For example, when the incident light from the light source is incident on the polarization element 1 at an incident angle θ of about 45° of skew, the incident light passes through the polarization element 1 and is separated into the first polarized light (S-polarized light: reflected light) and the second polarized light (P-polarized light: transmitted light). The S-polarized light is the light among the incident light having an electric field component in a direction parallel to the length direction of the rib portion 22 of the grating structure 20 ( Figure 2 the reflection axis direction shown: Y direction). On the other hand, the P-polarized light is the light among the incident light having an electric field component in a direction parallel to the width direction of the rib portion 22 of the grating structure 20 ( Figure 2 the transmission axis direction shown: X direction).

[0185] The S-polarized light in the reflection axis direction is mainly the 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 reflectance of the reflection axis (Rs). The reflectance of the reflection axis (Rs) represents the proportion of the S-polarized light reflected by the polarization element 1 among the S-polarized light incident on the polarization element 1. In addition, the transmittance of the reflection axis (Rp) represents the proportion of the S-polarized light transmitted through the polarization element 1 among the S-polarized light incident on the polarization element 1.

[0186] On the other hand, the P-polarized light in the transmission axis direction is mainly the transmitted light transmitted through the transparent grating structure 20 and the substrate 10 of the polarization element 1. The transmittance [%] of the P-polarized light at this time is the transmittance of the transmission axis (Tp). The transmittance of the transmission axis (Tp) represents the proportion of the P-polarized light transmitted through the polarization element 1 among the P-polarized light incident on the polarization element 1. In addition, the reflectance of the transmission axis (Ts) represents the proportion of the P-polarized light reflected by the polarization element 1 among the P-polarized light incident on the polarization element 1.

[0187] Therefore, the side with a higher transmittance Tp of the transmission axis means that P-polarized light in the direction of the transmission axis can be effectively transmitted. In addition, the side with a higher reflectance Rs of the reflection axis means that S-polarized light in the direction of the reflection axis can be effectively reflected. Thus, the side with a higher product of Tp and Rs, i.e., the Tp×Rs value, has high transmittance of P-polarized light (transmitted light) and high reflectance of S-polarized light (reflected light), and has excellent polarization separation characteristics as a polarization beam splitter.

[0188] Here, the preferred range of the value of Tp×Rs according to the present embodiment will be described. Considering the case where light with a specified wavelength range (for example, 430 to 680 nm) is incident obliquely on the polarization element 1 according to the present embodiment at a specified incident angle θ (for example, 45°) and is separated into P-polarized light (transmitted light) and S-polarized light (reflected light). In the case of such an oblique incidence condition, from the viewpoint of good polarization separation characteristics of the polarization element 1, Tp×Rs is preferably 70% or more.

[0189] When Tp×Rs is less than 70%, in a display device using the polarization element, the light utilization efficiency is poor, the brightness of the displayed image is insufficient, and the visual confirmation property is poor. In contrast, as long as Tp×Rs is 70% or more, the light utilization efficiency can be improved in a display device using the polarization element 1, sufficient brightness of the displayed image can be ensured, and the visual confirmation property can be improved.

[0190] Moreover, Tp×Rs is more preferably 72% or more, still more preferably 75% or more, and particularly preferably 80% or more. Thereby, the light utilization efficiency, the brightness of the displayed image, and the visual confirmation property as described above can be further improved.

[0191] <2.8. Preferred range of the height H of the rib portion>

[0192] 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 of the rib portion 22 of the grid structure 20 (refer to Figure 1 , Figure 3 etc.) is preferably 160 nm or more, more preferably 180 nm or more, and particularly preferably 220 nm or more (refer to Figure 24 ). Thereby, a high transmittance Tp of the transmission axis, excellent Tp×Rs characteristics, and a high contrast ratio CR of the transmitted light can be obtained.

[0193] Specifically, regarding the transmittance, as long as the height H of the rib portion 22 is 160 nm or more and the transmittance Tp of the transmission axis of the obliquely incident light is 80% or more, a high transmittance can be obtained. Moreover, as long as H is 180 nm or more, Tp of 85% or more can be obtained, so it is more preferable. In addition, as long as H is 220 nm or more, Tp of 87% or more can be obtained, so it is particularly preferable.

[0194] In addition, regarding the Tp×Rs characteristics required for a polarization beam splitter (PBS), as long as the height H of the rib portion 22 is 160 nm or more, excellent Tp×Rs of 70% or more can be obtained. Moreover, as long as H is 180 nm or more, Tp×Rs of 75% or more can be obtained, so it is more preferable. In addition, as long as H is 220 nm or more, Tp×Rs of 77% or more can be obtained, so it is particularly preferable.

[0195] In addition, regarding the contrast ratio CR of the transmitted light (CR = Tp / Ts), as long as the height H of the rib portion 22 is 100 nm or more, it is sufficient, but as long as H is 160 nm or more, excellent contrast ratio CR of 150 or more can be obtained. Moreover, as long as H is 180 nm or more, excellent CR of 250 or more can be obtained, so it is more preferable. In addition, as long as H is 220 nm or more, excellent CR of 500 or more can be obtained, so it is particularly preferable.

[0196] As described above, in order to make the various characteristics (Tp, Tp×Rs, CR) of the polarization element 1, especially Tp, good, it is preferable that the height H of the rib portion 22 is the higher one. The reason is considered as follows. That is, when the film-forming incident angle (refer to Figure 5 ) is the same, the lower the height H of the rib portion 22, the larger the coverage rate Rc achieved by the reflective film 30. When the coverage rate Rc increases, the range of the rib portion 22 covered by the reflective film 30 expands, so it is difficult for P-polarized light to pass through the grid structure 20, and the transmittance Tp decreases. Therefore, it can be said that under the condition of the same film-forming incident angle , it is preferable to reduce the coverage rate Rc by making the height H of the rib portion 22 higher, so as to increase the transmittance Tp.

[0197] <2.9. Preferred range of the front-end thickness Dt of the functional film (reflective film)>

[0198] When the incident light is incident on the polarization element 1 according to the present embodiment at a large incident angle θ (for example, 45°), the thickness Dt of the reflective film 30 covering the front end 22a of the rib portion 22 of the grid structure 20 (the front-end thickness Dt of the reflective film 30: Figure 5is preferably 5 nm or more, more preferably 15 nm or more (for example, refer to Figure 25 ).

[0199] As long as the front thickness Dt of the reflection film 30 is 5 nm or more, both the reflection axis reflectance Rs and the transmission axis transmittance Tp of the obliquely incident light are 85% or more, and high transmittance can be obtained. Moreover, considering the Tp characteristics and the Tp×Rs characteristics required for the polarization beam splitter, Dt is more preferably 15 nm or more.

[0200] <2.10. Preferred range of the side thickness Ds of the functional film (reflection film)>

[0201] In addition, the thickness Ds of the reflection film 30 covering the side surface 22b of the rib portion 22 of the grid structure 20 (the side thickness Ds of the reflection film 30: refer to Figure 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 (for example, refer to Figure 26 ). Thereby, high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and high contrast CR of transmitted light can be obtained.

[0202] Specifically, regarding the transmittance, as long as the side thickness Ds of the reflection film 30 is 10 nm or more and 30 nm or less, the transmission axis transmittance Tp of the obliquely incident light is 80% or more, and high transmittance can be obtained. Moreover, as long as Ds is 12.5 nm or more and 25 nm or less, Tp of 85% or more can be obtained, so it is more preferable.

[0203] In addition, regarding the reflectance, as long as the side thickness Ds of the reflection film 30 is 10 nm or more, the reflection axis reflectance Rs of the obliquely incident light is 80% or more, and high reflectance can be obtained. Moreover, as long as Ds is 12.5 nm or more, Rs of 85% or more can be obtained, so it is more preferable.

[0204] In addition, regarding the Tp×Rs characteristics required for the polarization beam splitter (PBS), as long as the side thickness Ds of the reflection film 30 is 12.5 nm or more and 30 nm or less, excellent Tp×Rs of 70% or more can be obtained. Moreover, as long as Ds is 15 nm or more and 25 nm or less, Tp×Rs of 76% or more can be obtained, so it is more preferable.

[0205] In addition, regarding the contrast CR of the transmitted light (CR = Tp / Ts), as long as the side thickness Ds of the reflection film 30 is 10 nm or more, but as long as Ds is 12.5 nm or more, excellent contrast CR of 50 or more can be obtained. Moreover, as long as Ds is 15 nm or more, CR of 100 or more can be obtained, so it is more preferable.

[0206] <2.11. Deviation of the Reflective Film>

[0207] In addition, in the polarization element 1 according to the present embodiment, the reflective film 30 covering the convex stripe portion 22 may also be deviated to one side of the convex stripe portion 22, and may have an asymmetrical shape in the width direction (X direction) of the convex stripe portion 22 (for example, refer to Figure 29 ). Specifically, between one side surface 22b and the other side surface 22b of the convex stripe portion 22, the side thickness Ds, the coverage rate Rc, etc. of the reflective film 30 may be changed to deviate the reflective film 30 to one side surface 22b of the convex stripe portion 22. That is to say, the reflective film 30 may thickly and widely cover one side surface 22b of the convex stripe portion 22, and thinly and narrowly cover the other side surface 22b.

[0208] In the case where the reflective film 30 is deviated to one side of the convex stripe portion 22 in this way, the difference between the transmissivity Tp(+) of the transmission axis of incident light with an incident angle of +θ (+30° to +60°) and the transmissivity Tp(-) of the transmission axis of incident light with an incident angle of -θ (-30° to -60°) with respect to the polarization element 1 is preferably within 3%. And preferably, the thickness Ds and the coverage rate Rc of the reflective film 30 covering one side surface 22b and the other side surface 22b of the convex stripe portion 22 are adjusted so that the difference between Tp(+) and Tp(-) is within 3%, so that the reflective film 30 is appropriately deviated to one side of the convex stripe portion 22.

[0209] In addition, an incident angle of +θ means that the obliquely incident light is incident from a direction inclined to one side in the X direction (the width direction of the convex stripe portion 22) with respect to the convex stripe portion 22. On the other hand, an incident angle of -θ means that the obliquely incident light is incident from a direction inclined to the other side in the X direction with respect to the convex stripe portion 22 (for example, refer to Figure 29 ).

[0210] As described above, in the case where the reflective film 30 is deviated to one side of the convex stripe portion 22, it is preferable that the difference between Tp(+) and Tp(-) is within 3%. Thereby, even in the case where the reflective film 30 is deviated to one side of the convex stripe portion 22, a high transmissivity Tp of the transmission axis, excellent Tp×Rs characteristics, and a high contrast CR of the transmitted light can be obtained.

[0211] Specifically, regarding the transmissivity, even in the case where the reflective film 30 is deviated to one side, the transmissivity Tp of the transmission axis of obliquely incident light with incident angles θ of +45° and -45° is 85% or more, and a high transmissivity can be obtained.

[0212] In addition, regarding the reflectivity, even in the case where the reflective film 30 is deviated to one side, the reflectivity Rs of the reflection axis of obliquely incident light with incident angles θ of +45° and -45° is 85% or more, and a high reflectivity can be obtained.

[0213] In addition, regarding the Tp×Rs characteristic required for a polarization beam splitter (PBS), even when the reflective film 30 is biased to one side, the Tp×Rs of the obliquely incident light with an incident angle θ of 45° is 75% or more, and excellent Tp×Rs characteristics can be obtained.

[0214] In addition, regarding the contrast ratio CR of transmitted light (CR = Tp / Ts), excellent contrast ratio CR can be obtained even when the reflective film 30 is biased to one side. Moreover, from the viewpoint of improving the contrast ratio, among the thicknesses Ds of the reflective film 30 covering one side surface 22b and the other side surface 22b of the convex strip portion 22 respectively, the thickness Ds of the thinner one is preferably 5 nm or more (the coverage rate Rc is 22% or more), and the thickness Ds of the thinner reflective film 30 is more preferably 10 nm or more (the coverage rate Rc is 33% or more).

[0215] <2.12. Other structural elements>

[0216] The polarization element 1 according to the present embodiment may also include structural elements other than the above-described substrate 10, grid structure body 20, and reflective film 30.

[0217] For example, as Figure 7 shown, the polarization element 1 preferably further includes a protective film 40 formed so as to cover at least the surface of the reflective film 30. Specifically, as Figure 7 shown, the protective film 40 more preferably covers the entire surface of the grid structure body 20. That is, the protective film 40 is more preferably formed so as to entirely cover the side surface 22b of the convex strip portion 22 of the grid structure body 20, the surface of the base portion 21, and the surface of the reflective film 30. By forming the protective film 40 involved, the scratch resistance, antifouling property, and waterproof property of the polarization element 1 can be further improved.

[0218] In addition, the protective film 40 more preferably further includes a hydrophobic coating or an oleophobic coating. Thereby, the antifouling property and waterproof property of the polarization element 1 can be further improved.

[0219] The material constituting the protective film 40 is not particularly limited as long as it can improve the scratch resistance, antifouling property, and waterproof property of the polarization element 1. As the material constituting the protective film 40, for example, a film made of a dielectric material can be cited. More specifically, inorganic oxides, silane-based hydrophobic materials, etc. can be cited. As the inorganic oxides, Si oxides, Hf oxides, etc. can be cited. The silane-based hydrophobic 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).

[0220] Among these materials, it is more preferably at least one of an inorganic oxide and a fluorine-based water-repellent material. By containing an inorganic oxide, the protective film 40 can further improve the scratch resistance of the polarizing element, and by containing a fluorine-based water-repellent material, the antifouling property and water resistance of the polarizing element can be further improved.

[0221] In addition, the protective film 40 may be formed so as to cover at least the surface of the reflective film 30, but preferably, as Figure 7 shown, it is formed so as to cover the entire surfaces of the grating structure 20 and the reflective film 30. In this case, for example, as Figure 7 shown in the upper figure, the protective film 40 may cover the end face of the grating structure 20 (the end face of the base portion 21), or as Figure 7 shown in the lower figure, the protective film 40 may not cover the end face of the grating structure 20 (the end face of the base portion 21). In addition, as Figure 8 shown, the protective film 40 may also cover the surface of the substrate 10 in addition to the surfaces of the grating structure 20 and the reflective film 30, and is formed so as to cover the whole polarizing element 1. In this way, by covering the outermost surface of the grating structure 20 or the polarizing element 1 with the protective film 40 made of an inorganic oxide, the overall thermal resistance R of the polarizing element 1 can be further reduced, so the heat dissipation performance of the polarizing element 1 is further improved.

[0222] Moreover, the polarizing element 1 according to the present embodiment is preferably provided with a heat dissipation member 50 so as to surround the periphery of the substrate 10, as Figure 9 shown. Through this heat dissipation member 50, the heat transferred from the substrate 10 can be released more effectively. Here, the heat dissipation member 50 is not particularly limited as long as it has a high heat dissipation effect. The heat dissipation member 50 can be, for example, a radiator, a heat sink, a heat spreader, a die pad, a heat pipe, a metal cover or frame, etc.

[0223] <2.13. Image of the actual grating structure>

[0224] Next, an example of actually manufacturing the polarizing element 1 according to the present embodiment and magnifying and photographing it with a scanning electron microscope (SEM) will be described with reference to Figure 10 . Figure 10 A in Figure 10 is an SEM image of the grating structure 20 before being covered with the reflective film 30, observed obliquely. Figure 10 B in

[0225] As Figure 10 shown by A of Figure 10 and B of T below, a base portion 21 provided along the surface of the substrate 10 and a rib portion 22 protruding from the base portion 21 are formed in the grid structure body 20. A plurality of rib portions 22 are arranged at substantially equal intervals P. Each rib portion 22 has a tapered shape with a width that tapers as it moves away from the base portion 21. The width W B of the top of the rib portion 22 is B narrower than the width W Figure 10 of the bottom of the rib portion 22. The interval P is sufficiently larger than the width W T of the bottom of the rib portion 22. The height H of the rib portion 22 is greater than the interval P. B In the example of Figure 10 below, P = 140 nm, W

[0226] <3. Manufacturing method of polarizing element>

[0227] Next, with reference to Figure 11 below, the manufacturing method of the wire grid polarizing element 1 according to the present embodiment will be described. Figure 11 is a process diagram showing the manufacturing method of the wire grid polarizing element 1 according to the present embodiment.

[0228] As described above, the polarizing element 1 according to the present embodiment is a hybrid wire grid polarizing element 1 composed of an inorganic material (substrate 10) and an organic material (grid structure body 20). The manufacturing method of this hybrid wire grid polarizing element 1 will be described below.

[0229] As Figure 11 shown below, the manufacturing method of the wire grid polarizing element 1 according to the present embodiment includes: a grid structure body material forming step (S10), a nanoimprinting step (S12), a grid structure body forming step (S14), and a reflective film forming step (S16).

[0230] Grid structure body material forming step (S10)

[0231] First, in S10, on a substrate 10 made of a transparent inorganic material (such as glass), a grid structure material 23 made of a transparent organic material (such as an ultraviolet curable resin or a thermosetting resin) is laminated by coating or the like. In addition, as the inorganic material of the substrate 10, various materials described above can be used. In addition, as the organic material of the grid structure 20, various materials described above can be used. Moreover, the film thickness of the grid structure material 23 can be appropriately adjusted according to the sizes of the base portion 21 and the protruding strip portions 22 of the grid structure 20 formed by nanoimprinting in S20.

[0232] Nanoimprinting process (S12) and grid structure forming process (S14)

[0233] Next, in S12, by performing nanoimprinting on the grid structure material 23, a grid structure 20 is formed on the substrate 10 in S14. 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 protruding strip portions 22 protruding from the base portion 21 are integrally formed. The fine concavo-convex structure is, for example, a structure having fine convex portions and concave portions on the order of several nm to several tens of nm.

[0234] In the nanoimprinting process of S12, a master disk 60 having an inverted shape of the fine concavo-convex shape of the grid structure 20 is used to transfer the fine concavo-convex shape of the master disk 60 to the surface of the grid structure material 23 (S12). As a result, an uneven pattern composed of the base portion 21, the protruding strip portion 22, and the concave portion 24 is formed in the grid structure material 23. Moreover, in the nanoimprinting process, by transferring the uneven pattern and irradiating the grid structure material 23 with energy rays, the grid structure material 23 with the transferred uneven pattern is cured to form the grid structure 20 (S14). For example, when the grid structure material 23 is made of an ultraviolet curable resin, an ultraviolet irradiation device 66 can be used to irradiate the grid structure material 23 with ultraviolet rays to cure the ultraviolet curable resin with the transferred uneven pattern. Alternatively, when the grid structure material 23 is made of a thermosetting resin, a heating device 68 such as a heater can be used to heat the grid structure material 23 to cure the thermosetting resin with the transferred uneven pattern.

[0235] In the above-described processes S12 and S14, as the protruding strip portion 22 of the grid structure 20, a protruding strip portion 22 having a tapered shape in which the width becomes narrower as it is farther from the base portion 21 is formed. Figure 11 The example of the protruding strip portion 22 is a trapezoidal shape (widening shape), but as Figure 3 shown, it can also be other various tapered shapes.

[0236] Thus, in the present embodiment, since the convex strip portion 22 having a head-thin shape is imprinted in the nanoimprinting step S12, the master disk 60 can be easily peeled off from the grid structure material 23, and the releasability is excellent. In addition, the desired shape can be accurately formed without deforming the convex strip portion 22 of the grid structure 20.

[0237] Reflective film forming step (S16)

[0238] Next, in S16, a reflective film 30 that covers a part of the convex strip portion 22 of the grid structure 20 is formed of 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 lines) for reflecting the incident light incident on the grid structure 20 of the polarization element 1.

[0239] In this reflective film forming step S16, the reflective film 30 is formed in the following manner. That is, the reflective film 30 is formed so as to cover the front end 22a of the convex strip portion 22 and the upper side of at least one side surface 22b, and does not cover the lower side of the two side surfaces 22b and the base portion 21 of the convex strip portion 22. Moreover, the surface of the reflective film 30 covering the convex strip portion 22 is formed in a shape with a round shape and bulging in the width direction of the convex strip portion 22. In addition, the maximum width W MAX (grid maximum width W MAX ) becomes the width W of the bottom of the aforementioned convex strip portion B (grid bottom width W B ) or more to form the reflective film 30.

[0240] As a method for forming such a reflective film 30, for example, as Figure 5 shown, sputtering or evaporation can be used. The metal material is alternately sputtered or evaporated from an oblique direction with respect to the convex strip portion 22 of the grid structure 20 to form the reflective film 30. Thereby, the reflective film 30 having a desired shape can be appropriately formed so as to roundly cover the top of the convex strip portion 22.

[0241] By forming the reflective film 30 in this way, the convex strip portion 22 of the grid structure 20 and the reflective film 30 have the above-described special tree shape. Thus, as described above, even when light is obliquely incident on the polarization element 1 at a large and wide range of incident angles θ (for example, 30 to 60°), the transmittance Tp of the transmission axis of the P-polarized light contained in the obliquely incident light can be maintained at a high value, and the transmissivity of the P-polarized light (transmitted light) can be ensured. Thereby, the value of Tp × Rs can be maintained at a high value (for example, 70% or more), so that the polarization separation characteristics of the polarization element 1 with respect to obliquely incident light can be improved.

[0242] In addition, the manufacturing method of the polarization element 1 according to the present embodiment may also, after the reflection film forming step S16 shown in Figure 11 as needed, include a step of forming a protective film 40 covering the surface of the polarization element 1 (protective film forming step). The protective film 40 is preferably formed so as to cover the entire surfaces of the grid structure body 20 and the reflection film 30. As the material of the protective film 40, various materials described above can be used.

[0243] The manufacturing method of the polarization element 1 according to the present embodiment has been described above. Through the above steps, it is possible to manufacture the polarization element 1 having excellent polarization characteristics and heat dissipation properties without causing a significant increase in the manufacturing cost and complexity of the polarization element 1.

[0244] Here, in order to compare with the manufacturing method according to the present embodiment, reference is made to Figure 1 to briefly describe the manufacturing method of the existing wire grid polarization element.

[0245] As Figure 12 shown, in the manufacturing method of the existing 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 reflection film made of a material that reflects light in the used wavelength band, for example, a metal film 80 such as aluminum, is formed by sputter or evaporation.

[0246] Next, a resist mask 70 is patterned on the metal film 80 by photolithography (S22). Then, the metal film 80 is etched by a vacuum dry etching device or the like to form a convex shape made of the metal film 80 (S24). For example, at this time, in the case where the etching selectivity between the resist mask 70 and the metal film 80 cannot be obtained, an oxide film such as SiO2 is further formed on the metal film 80 by sputtering or the like, and a resist mask 70 is formed thereon by photolithography. Then, after the resist mask 70 is peeled off 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 hydrophobic / oil-repellent coating treatment is also performed as needed (S28).

[0247] In addition, the steps S20 to S28 of the above-described existing manufacturing method show the process of manufacturing a basic structure reflection type wire grid polarization element. However, when considering the case where the metal film 80 is a multilayer film, a more complex process is required. Therefore, it is speculated that by Figure 12The manufacturing cost of an existing wire grid polarizing element manufactured by a process such as that shown in S20 to S28 of

[0248] becomes expensive, and the time required for manufacturing also increases. In addition, it is also speculated that in the case of mass-producing polarizing elements, in order to form fine convex shapes smaller than the wavelength of light, it is necessary to prepare multiple expensive etching devices and lithography devices with excellent precision according to the production volume, and the equipment investment will also become more expensive. Figure 11 In contrast, the manufacturing method of the polarizing element 1 according to the present embodiment (refer to Figure 12 ) uses an imprinting technique such as nanoimprinting to form the grid structure 20, so compared with the above-described existing manufacturing method (refer to

[0249] ), the manufacturing cost, manufacturing time, and equipment investment can be significantly reduced. Figure 11 In the polarizing element 1 according to the present embodiment, nanoimprinting ( Figure 11 S12 of

[0250] ) is performed on the grid structure material 23, and the conditions for nanoimprinting are not particularly limited. For example, as shown in S12 of Figure 11 , a replication master (which may also be an original master) is used as the master disk 60 for nanoimprinting, and UV irradiation or heating is performed on the grid structure material 23, etc., and the grid structure material 23 is cured in a state where the concave and convex pattern is imprinted. Then, the master disk 60 is demolded from the cured grid structure material 23. Thus, the grid structure 20 having the base portion 21 and the ridge portion 22 formed thereon can be formed by transfer. Figure 13 In addition, the master disk 60 used in the nanoimprinting step S12 ( Figure 13 in the manufacturing method of the polarizing element 1 according to the present embodiment) can be manufactured by a lithography technique, for example, as shown in

[0251] Figure 13 . First, a master disk metal film 62 is formed on a master disk base material 61 (S30), and then 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 grooves 65 corresponding to the ridge portions 22 of the grid structure 20 are formed in the etched master disk metal film 62 (S34).

[0252] Then, by peeling the resist mask 70 from the master disk with the metal film 62, the master disk 60 can be obtained (S36). The master disk 60 has a fine concavo-convex structure formed on the master disk substrate 61, which consists of a plurality of convex portions 63 and grooves 65. 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 body 20 of the above-mentioned polarization element 1. The groove 65 of the master disk 60 has an inverted shape of the rib portion 22 of the grid structure body 20, and the convex portion 63 of the master disk 60 has an inverted shape of the concave portion 24 between the rib portions 22, 22 of the grid structure body 20.

[0253] Moreover, the manufacturing method according to the present embodiment may further include a step (S38) of forming a release film coating 64 on the surface of the fine concavo-convex structure of the master disk 60 as needed. By providing the release film coating 64 on the surface of the master disk 60, after performing nanoimprinting on the grid structure material 23 in the nanoimprinting step (S12) shown above, the master disk 60 can be easily separated from the grid structure material 23, further improving the releasability. Figure 11 shown, the releasability can be further improved.

[0254] <4. Projection display device>

[0255] Next, with reference to Figure 14 a projection display device using the wire grid polarizing element 1 according to the present embodiment will be described.

[0256] The projection display device according to the present embodiment includes the wire grid polarizing element 1 according to the present embodiment described above. By including the polarizing element 1, the projection display device according to the present embodiment can achieve excellent polarization characteristics, heat resistance, heat dissipation, etc. of the polarizing element 1.

[0257] Here, the projection display device projects light toward an object, and displays a virtual image such as an image or video by irradiating the projected light (projection light) onto the display surface (projection surface) of the object. As the types of projection display devices, for example, a head-up display device (HUD), a projector device, etc. can be cited.

[0258] <4.1. Head-up display device>

[0259] First, with reference to Figure 14 a head-up display device 100 including the wire grid polarizing element 1 according to the present embodiment will be described. Figure 14 is a schematic diagram showing an example of the head-up display device 100 according to the present embodiment.

[0260] As shown in Figure 14As shown, 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 including the polarizing element 1, the head-up display device 100 can improve polarization characteristics, heat resistance, and heat dissipation. Since the heat dissipation of a head-up display equipped with an existing polarizing element is poor, considering long-term use and future high brightness / amplified display, it can be considered that the heat resistance is insufficient.

[0261] As Figure 14 shown, 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 toward a display surface 5, and a cover portion 6 provided at an opening of a cover 7. In the head-up display device 100, the arrangement of the polarizing element 1 is not particularly limited. For example, as Figure 14 shown, the polarizing element 1 can be arranged between the display element 3 and the reflector 4.

[0262] Here, the head-up display device 100 can also 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 (equivalent to the "display surface 5") such as a windshield or a combiner of the vehicle. The vehicle head-up display device is, for example, disposed on the instrument panel of the vehicle, projects image light onto the windshield (display surface 5), and displays operation information as a virtual image.

[0263] The head-up display device 100 is configured to emit a display image toward the windshield surface (display surface 5) from below. Therefore, sunlight may enter from the opposite direction of the emission direction of the display image and be incident on the display element 3. In the head-up display device 100 according to the present embodiment, a reflector 4 for reflecting and magnifying the display image is provided for the purpose of miniaturization and magnification of the display image. In such a case, in an existing head-up display device, sunlight incident on the reflector from the outside is condensed near the display element, and there is a possibility of deterioration or failure of the display element due to heat.

[0264] In contrast, in the head-up display device 100 according to the present embodiment, for the purpose of preventing sunlight from hitting the display element 3, as described above, a polarizing element 1 with excellent heat dissipation and heat resistance of a hybrid type is provided. The polarizing element 1 can stably exhibit a polarization function even at a high temperature of, for example, about 200°C. Therefore, for example, even in a high-temperature environment such as inside a vehicle in summer, the polarizing element 1 can block sunlight incident on the reflector 4 from the outside to prevent it from reaching the display element 3, so that deterioration and failure of the display element 3 can be suppressed.

[0265] In addition, Figure 14The structural elements of the head-up display device 100 shown are examples of basic structural elements, and the structural elements of the projection display device are not limited to Figure 14 the examples, and other structural elements may be appropriately provided according to the required performance and the like.

[0266] In addition, by using the polarization element 1 as a pre-polarizing plate disposed in front of the display element 3, the polarization element 1 can transmit the display image emitted from the display element 3 and suppress sunlight from entering the display element 3. Therefore, the heat resistance and durability of the head-up display device 100 can be further improved.

[0267] In addition, the arrangement of the wire grid polarizing element in the projection display device is not limited to Figure 14 the example of the arrangement of the polarization element 1 in the head-up display device 100 shown, and can be appropriately selected and changed according to the structure of the projection display device, the required performance, etc. For example, although not shown, the polarization element 1 can be disposed between the display element 3 and the light source 2. In addition, although not shown, the polarization element 1 can also be assembled into the reflector 4. Moreover, Figure 14 the cover portion 6 provided in the head-up display device 100 shown can also be constituted by the polarization element 1.

[0268] In addition, although not shown, a heat dissipation member 50 (see Figure 9 ) can also be provided around the polarization element 1 installed in the head-up display device 100. Through this heat dissipation member 50, the heat dissipation performance of the polarization element 1 can be further improved, so the polarization characteristics and heat resistance of the polarization element 1 can be further improved.

[0269] <4.2. Projection Display Device with Polarization Beam Splitter>

[0270] Next, a projection display device that uses the reflective wire grid polarizing element 1 according to the present embodiment as a polarization beam splitter 230 will be described with reference to Figures 15 - 17 . First, the common matters in the three specific examples of the projection display devices 200A, 200B, and 200C (hereinafter sometimes collectively referred to as "projection display device 200") shown in Figures 15 - 17 will be inclusively described. Then, each specific example shown in Figures 15 - 17 will be individually described.

[0271] As shown in Figures 15 - 17 , the projection display device 200 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. In addition, a retardation compensation plate (not shown) can also be provided between the polarization beam splitter 230 and the reflective liquid crystal display element 240.

[0272] The light source 210 can be a point light source having one light emitting part, or a light source having a plurality of light emitting parts such as an LED. In addition, the light emitted from the light source 210 can be parallel light or diffused light. Therefore, the light from the light source 210 sometimes enters the polarization beam splitter 230 (reflection type wire grid polarizer) at an incident angle θ within a specified range centered on, for example, 45° (for example, a range of 45° ± 15°).

[0273] The PS converter 220 is a polarization conversion element for converting the light from the light source 210 into specific polarized light (for example, P-polarized light or S-polarized light). The PS converter 220 can convert the light from the light source 210 into P-polarized light or S-polarized light.

[0274] The polarization beam splitter 230 is composed of a reflection type wire grid polarizer. The reflection type wire grid polarizer is an example of the wire grid polarizing element 1 according to the present embodiment. The polarization beam splitter 230 is configured such that the light from the light source 210 enters at an incident angle θ within a specified range including 45°. The incident angle θ of this specified range is, for example, the above-mentioned 45° ± 15°, that is, 30° or more and 60° or less.

[0275] For example, Figures 15 - 17 In, the polarization beam splitter 230 is arranged obliquely at 45° with respect to the incident direction of the incident light so that the incident light from the light source 210 enters the polarization beam splitter 230 mainly at an incident angle θ of 45°. In addition, the polarization beam splitter 230 is arranged obliquely at 45° with respect to the reflective liquid crystal display element 240 so that the incident light from the reflective liquid crystal display element 240 enters the polarization beam splitter 230 mainly at an incident angle θ of 45°.

[0276] The polarization beam splitter 230 separates the incident light into first polarized light (S-polarized light) and second polarized light (P-polarized light). For example, the polarization beam splitter 230 can also separate the S-polarized light and the P-polarized light by reflecting the first polarized light (S-polarized light) among the incident light and transmitting the second polarized light (P-polarized light). On the contrary, the polarization beam splitter 230 can also separate the S-polarized light and the P-polarized light by reflecting the second polarized light (P-polarized light) among the incident light and transmitting the first polarized light (S-polarized light).

[0277] The polarization beam splitter 230 is arranged in such a way that when the desired polarized light is reflected by the polarization beam splitter 230, the surface of the polarization beam splitter 230 (that is, the uneven surface on the side where the grid structure 20 of the polarization element 1 is formed) is incident with light including the polarized light to be reflected. For example, as Figure 15As shown, when reflecting the S-polarized light incident from the PS converter 220 by the polarization beam splitter 230, it is only necessary to orient the surface of the polarization beam splitter 230 toward the PS converter 220 side from which the S-polarized light is emitted. On the other hand, as Figure 16 shown, when reflecting the S-polarized light incident from the reflective liquid crystal display element 240 by the polarization beam splitter 230, it is only necessary to orient the surface of the polarization beam splitter 230 toward the reflective liquid crystal display element 240 side from which the S-polarized light is emitted.

[0278] The reflective liquid crystal display element 240 is a display element that reflects incident light and emits light presenting a display image. The reflective liquid crystal display element 240 can also be configured in the following manner, i.e., as Figure 15 and Figure 17 shown, making the first polarized light (S-polarized light) reflected by the polarization beam splitter 230 incident on the surface of the reflective liquid crystal display element 240. Alternatively, the reflective liquid crystal display element 240 can also be configured in the following manner, i.e., as Figure 16 shown, making the second polarized light (P-polarized light) passing through the polarization beam splitter 230 incident on the surface of the reflective liquid crystal display element 240.

[0279] In addition, as Figure 15 and Figure 17 shown, the reflective liquid crystal display element 240 reflects and modulates the incident first polarized light (S-polarized light) and emits the second polarized light (P-polarized light) presenting a display image. However, it is not limited to the examples involved, and the following manner can also be adopted, i.e., as Figure 16 shown, the reflective liquid crystal display element 240 reflects and modulates the incident second polarized light (P-polarized light) and emits the first polarized light (S-polarized light) presenting a display image.

[0280] The lens 250 magnifies the light presenting a display image emitted from the reflective liquid crystal display element 240 and outputs it to the outside. The lens 250 is configured in such a way that the light presenting a display image emitted from the reflective liquid crystal display element 240 passes through the polarization beam splitter 230 and is incident. For example, the lens 250 can also be configured in the following manner, i.e., as Figure 15 and Figure 17 shown, making the second polarized light (P-polarized light) reflected and modulated by the reflective liquid crystal display element 240 pass through the polarization beam splitter 230 and be incident on the lens 250. Alternatively, the lens 250 can also be configured in the following manner, i.e., as Figure 16 shown, making the first polarized light (S-polarized light) reflected and modulated by the reflective liquid crystal display element 240 pass through the polarization beam splitter 230 and be incident on the lens 250.

[0281] 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 is used as the polarization beam splitter 230. Therefore, the polarization beam splitter 230 has excellent reflectivity of S-polarized light, transmittance of P-polarized light, and Tp×Rs characteristics for obliquely incident light with a large and wide range of incident angles θ (for example, 30 to 60°), and excellent characteristics of separating obliquely incident light into P-polarized light and S-polarized light.

[0282] Next, each specific example of the projection display devices 200A, 200B, and 200C shown in Figures 15 - 17 will be described individually.

[0283] As Figure 15 shown, 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.

[0284] The light emitted from the light source 210 is unpolarized light, which contains P-polarized light components and S-polarized light components in the same proportion. Therefore, if only one of the polarized lights is selected and extracted by the polarization beam splitter 230 composed of the polarizing element 1, the light quantity will be reduced to about half. Therefore, the light emitted from the light source 210 is converted into one of the first polarized light (S-polarized light) or the second polarized light (P-polarized light) by the PS converter 220. Thereby, it is possible to suppress the reduction of the light quantity of the polarized light extracted by the polarization beam splitter 230, and improve the light utilization efficiency. For example, Figure 15 the PS converter 220 shown in

[0285] converts the light from the light source 210 into the first polarized light (S-polarized light). The light converted into S-polarized light by the PS converter 220 is incident on the polarization beam splitter 230 arranged obliquely at an angle of about 45°. The polarization beam splitter 230 reflects the first polarized light (S-polarized light) 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 polarized light (S-polarized light) to generate the second polarized light (P-polarized light) presenting 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, and after being magnified by the lens 250, is projected onto a display surface (not shown) to display the display image.

[0286] The projection display device 200A having the above structure includes a reflective wire grid polarizer formed of the wire grid polarizing element 1 according to the present embodiment as the polarization beam splitter 230. Thus, for obliquely incident light and incident light with a wide incident angle θ, the polarization separation characteristics of the polarization beam splitter 230 can be improved, and the heat dissipation and heat resistance of the polarization beam splitter 230 and the projection display device 200A can be improved.

[0287] On the other hand, in a projection display device (not shown) having an existing polarizing element as the polarization beam splitter, the heat dissipation of the polarizing element is poor. Therefore, from the viewpoints of coping with long-term use, high brightness, and enlarged display, it is considered that the heat resistance is insufficient. In addition, the incident angle θ of the light incident on the polarization beam splitter is not only 45°, but also all angles within a specified 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, regardless of the incident angle θ, the polarization beam splitter is required to have the performance of appropriately separating the obliquely incident light into S-polarized light and P-polarized light. However, in a polarization beam splitter using an existing polarizing element, the polarization separation characteristics for the above-mentioned obliquely incident light are poor, so the light utilization efficiency deteriorates and the adverse effects on the image quality of the display image such as brightness unevenness become a problem.

[0288] 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, the brightness unevenness can be reduced, and the image quality of the display image can be improved.

[0289] In addition, the projection display device is not limited to the example of the projection display device 200A shown above Figure 15 For example, as shown in Figure 16 the projection display device 200B, or, Figure 17 as shown in

[0290] the projection display device 200C, etc., the structural elements and configurations of the projection display device can be appropriately changed. Figure 16 As shown in

[0291] In the projection display device 200B, the PS converter 220 converts the light from the light source 210 into second polarized light (P-polarized light). The light converted into P-polarized light by the PS converter 220 passes through the polarization beam splitter 230 disposed obliquely at an angle of 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 polarized light (P-polarized light), generates first polarized light (S-polarized light) presenting a display image, and projects the first polarized light (S-polarized light) onto the polarization beam splitter 230. The polarization beam splitter 230 reflects the first polarized light (S-polarized light) and projects it onto the lens 250 at an emission angle of 45°. After the first polarized light (S-polarized light) is amplified by the lens 250, it is projected onto a display surface (not shown), and the display image is displayed.

[0292] The projection display device 200B having the above structure, similar to the above-described projection display device 200A (refer to Figure 15 ), has excellent polarization separation characteristics for obliquely incident light, can improve the light utilization efficiency and reduce brightness unevenness, and can improve the image quality of the display image.

[0293] In addition, as Figure 17 shown, the projection display device 200C according to the second 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 may not include the above-described PS converter 220.

[0294] 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 an angle of about 45°. The polarization beam splitter 230 reflects the component of the first polarized light (S-polarized light) in the non-polarized light and projects it onto 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 polarized light (P-polarized light) passes through the polarization beam splitter 230 and is incident on the light absorber 260. Since the component of the second polarized light (P-polarized light) is almost absorbed by the light absorber 260, it is possible to suppress the unnecessary second polarized light (P-polarized light) from entering other optical systems within the projection display device 200C.

[0295] 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, generates second polarized light (P-polarized light) presenting a display image, and projects the second polarized light (P-polarized light) onto the polarization beam splitter 230. The second polarized light (P-polarized light) passes through the polarization beam splitter 230, is amplified by the lens 250, and then is projected onto a display surface (not shown), and the display image is displayed.

[0296] In the projection display device 200C having the above structure, the PS converter 220 is not provided. Therefore, 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 there is no display for image display. As a result, the amount of light for image display is reduced to approximately half. However, 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. Therefore, it has the advantages of being able to reduce the cost of the projection display device 200C and miniaturize the projection display device 200C.

[0297] The above has described a specific example of the projection display device 200 that uses the reflective wire grid polarizing element 1 according to the present embodiment as the polarization beam splitter 230. In addition, the projection display device is not limited to Figures 15 - 17 the specific example of the projection display device 200 shown. The structural elements and arrangements of the projection display device can be appropriately changed according to the required performance, etc., or other structural elements can be appropriately provided.

[0298] <5. Vehicle>

[0299] Next, a vehicle equipped with the image display device according to the present embodiment will be described.

[0300] The vehicle (not shown) according to the present embodiment includes: a projection display device having the wire grid polarizing element 1 according to the above-described present embodiment. In addition, as long as the vehicle is a vehicle on which a projection display device can be installed, for example, it can be various automobiles such as ordinary passenger cars, light motor vehicles, buses, trains, racing cars, construction work vehicles, and other large vehicles. In addition to these, it can also be various transportation means such as motorcycles, trams, maglev trains, and amusement facility transportation means.

[0301] The vehicle according to the present embodiment can project and display a display image on a display surface (for example, Figure 14 the display surface 5 shown) provided on the vehicle through the above-described polarizing element 1 and the projection display device. The display surface is preferably, for example, a semi-transparent plate such as the windshield (front glass), side glass, rear glass, or combiner of the vehicle. However, the display surface is not limited to the examples described, and as long as it is the surface of an object on which an image can be projected and displayed, it can also be the surface of various components, parts, and in-vehicle mechanical equipment provided on the vehicle.

[0302] The projection display device provided on the vehicle according to the present embodiment is, for example, Figure 14 the head-up display device 100 shown, or Figures 15 - 17A projection display device 200 having a polarization beam splitter 130 as shown, etc. However, it is not limited to the examples involved. As long as the projection display device is a device capable of projecting or displaying an image, it can also be various image display devices such as a projector mounted on a vehicle, a car navigation device, and a terminal device having an image display function.

[0303] As described above, in the head-up display device 100, as Figure 14 shown, sunlight sometimes enters the head-up display device 100 from the outside of the vehicle through the windshield (display surface 5). Due to the heat of this sunlight, etc., deterioration and failure of the display element 3 may occur. Therefore, for the purpose of preventing sunlight from hitting the display element 3, the above-described hybrid wire grid polarizing element 1 is provided in the head-up display device 100. Since the polarizing element 1 has a hybrid structure with high thermal conductivity, it has excellent heat dissipation and heat resistance. Therefore, by the polarizing element 1 blocking the sunlight incident from the outside into the head-up display device 100, it is possible to prevent it from reaching the display element 3, so that failure and breakage of the display element 3 can be prevented. Moreover, since the polarizing element 1 has excellent heat dissipation and heat resistance, breakage of the polarizing element 1 itself can also be prevented.

[0304] Similarly, even when Figures 15 - 17 shown, when the projection display device 200 is provided in a vehicle, the polarizing element 1 used as the polarization beam splitter 230 can also block sunlight from the outside, so that failure and breakage of other components such as the reflective liquid crystal display element 240 can be prevented. Moreover, breakage of the polarizing element 1 itself with excellent heat dissipation and heat resistance can also be prevented.

[0305] 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, polarization separation characteristics, etc.) through the polarizing element 1 and can also achieve excellent heat resistance and durability of the projection display device.

[0306] In addition, the vehicle is not particularly limited as long as it has 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.

[0307] <6. Organic material (UV-curable acrylic resin for imprinting) constituting the grid structure>

[0308] Next, the organic material (UV-curable acrylic resin for imprinting) constituting the grid structure 20 according to the present embodiment will be described.

[0309] As a technique for manufacturing a resin optical component having a fine concavo-convex structure, imprinting of an uncured resin layer composed of an uncured resin composition is widely used. In imprinting, by pressing the fine concavo-convex shape of a master disk onto the uncured resin layer formed on a substrate, and curing the uncured resin layer in this state, and then peeling off the master disk, a fine concavo-convex shape can be formed on the substrate.

[0310] In imprinting, if the thickness (layer thickness) of the uncured resin layer when pressing the master disk is uneven, the peeling force applied when peeling off the master disk from the cured resin layer (hereinafter referred to as "cured resin layer") becomes uneven in the plane of the cured resin layer. In this way, it may cause a part of the cured resin layer to peel off from the substrate. In addition, the cured resin layer peeled off from the substrate remains on the master disk, making it impossible to reuse the master disk repeatedly. Moreover, when peeling off the master disk, the fine concavo-convex shape transferred to the cured resin layer may be deformed, and the optical characteristics caused by the fine concavo-convex structure may deteriorate.

[0311] In addition, in imprinting, when pressing the master disk, if the followability of the uncured resin composition to the fine concavo-convex shape is low, a portion of the fine concavo-convex shape of the master disk that is not transferred will be generated in the uncured resin layer.

[0312] Therefore, in order to make the layer thickness of the uncured resin layer uniform when pressing the master disk and improve the followability of the uncured resin composition to the fine concavo-convex shape, a technique for reducing the viscosity of the uncured resin composition has been developed (for example, as described in Japanese Patent Application Laid-Open No. 2018-125559 and Japanese Patent No. 4824068).

[0313] In order to reduce the viscosity of the uncured resin composition, it is conceivable to increase the content ratio of monofunctional monomers and low-viscosity bifunctional monomers in the resin composition.

[0314] However, if the content ratio of monofunctional monomers and low-viscosity bifunctional monomers is increased, there is a problem that the heat resistance of the cured resin layer decreases.

[0315] Therefore, an object of the present embodiment is to provide a photocurable acrylic resin for imprinting that reduces the viscosity of the uncured resin composition and has excellent heat resistance of the cured resin composition.

[0316] The photocurable acrylic resin used in this embodiment is an uncured resin composition. The photocurable acrylic resin used in this embodiment is composed of a photopolymerizable component and a photoinitiator. The photopolymerizable component in this embodiment is one of the above-mentioned acrylic polymerizable compounds. In addition, the photoinitiator involved in this embodiment is a substance for polymerizing the photopolymerizable component, corresponding to the above-mentioned photocuring initiator.

[0317] <6.1. Composition of Photopolymerizable Component>

[0318] Next, the composition of the photopolymerizable component of the photocurable acrylic resin used in this embodiment will be described. The photopolymerizable component involved in this embodiment includes at least resin (A) and resin (B). In addition, the photopolymerizable component involved in this embodiment may include either or both of resin (C) and resin (D) in addition to resin (A) and resin (B). In addition, the photopolymerizable component involved in this embodiment may be composed only of resin (A) and resin (B), may be composed only of resin (A), resin (B) and resin (C), may be composed only of resin (A), resin (B) and resin (D), or may be composed only of resin (A), resin (B), resin (C) and resin (D). Resins (A) to (D) will be described below.

[0319] Resin (A) is (Octahydro-4,7-methano-1H-indendiyl)Bis(methylene)diacrylate. That is, resin (A) is a bifunctional acrylate monomer represented by the following chemical formula (II). As resin (A), for example, "KAYARAD R-684" manufactured by Nippon Kayaku Co., Ltd. can be used.

[0320]

Chemical Formula 1

[0321]

[0322] Resin (A) has a viscosity of 100 mPa·s or more and 250 mPa·s or less at 25°C. In addition, the viscosity is the viscosity of a liquid using a rotational viscometer and a vibrating viscometer based on JIS Z8803. The viscosity is measured using a cone plate, for example, in a Brookfield viscometer manufactured by Eiko Seiki Co., Ltd.

[0323] Resin (B) is a bifunctional acrylate monomer having a viscosity of 10 mPa·s or less at 25°C. Resin (B) is preferably a bifunctional acrylate monomer having a viscosity of 3 mPa·s or more at 25°C. In addition, resin (B) is a bifunctional acrylate monomer having a structurally flexible structure. Here, being structurally flexible means having a structure that is prone to molecular movement, bending, and stretching when heated. Resin (B) can be a bifunctional acrylate monomer in which acryloyl groups are bonded to both ends of a linear structure composed of a hydrocarbon group, or a bifunctional acrylate monomer in which acryloyl groups are bonded to both ends of a linear structure having an ether bond. Here, the hydrocarbon group is, for example, one or more selected from the group consisting of an alkyl group, an alkylene group, and an alkynyl group.

[0324] A bifunctional acrylate monomer in which acryloyl groups are bonded to both ends of a linear structure composed of a hydrocarbon group can be, for example, a bifunctional acrylate monomer represented by the following chemical formula (I). In chemical formula (I), n is preferably an integer of 1 or more and 9 or less, more preferably an integer of 6 or more and 9 or less, and still more preferably 6 or 9.

[0325] CH2=CHCOO(CH2) n OOCCH=CH2…(I)

[0326] When n is 6 in the above chemical formula (I), that is, when resin (B) is 1,6 - hexanediol diacrylate, resin (B) has a viscosity of 6.5 mPa·s at 25°C. In addition, when n is 9 in the above chemical formula (I), that is, when resin (B) is 1,9 - nonanediol diacrylate, resin (B) has a viscosity of 8 mPa·s at 25°C.

[0327] A bifunctional acrylate monomer in which acryloyl groups are bonded to both ends of a linear structure having an ether bond can be, for example, dipropylene glycol diacrylate (DPGDA).

[0328] Resin (C) is preferably an acrylate monomer having a viscosity of 10 mPa·s or less at 25°C. Resin (C) is preferably an acrylate monomer having a viscosity of 1 mPa·s or more at 25°C. In addition, resin (C) is preferably an acrylate monomer having a structurally rigid structure. Here, being structurally rigid means having a structure that is difficult for molecular movement, bending, and stretching when heated. Resin (C) can be, for example, an acrylate monomer having any one or both of a cyclic structure composed only of single bonds and a cyclic structure composed of single bonds and multiple bonds (such as a benzene ring). In addition, the number of acryloyl groups of resin (C) is not particularly limited, and resin (C) is, for example, a monofunctional acrylate monomer.

[0329] The resin (C) can be, for example, isobornyl acrylate.

[0330] When the resin (C) is isobornyl acrylate, the resin (C) has a viscosity of 9.5 mPa·s at 25°C.

[0331] The resin (D) is preferably an acrylate monomer having three or more functional groups. The resin (D) is preferably an acrylate monomer having six or fewer functional groups. The resin (D) is preferably an acrylate monomer having three or more and six or fewer functional groups. The resin (D) can be, for example, one or more selected from the group consisting of trimethylolpropane triacrylate (TMPTA), dipentaerythritol hexaacrylate (DPHA), and polyfunctional polyester acrylate. As the polyfunctional polyester acrylate, for example, “M-9050” manufactured by Toagosei Co., Ltd. can be used.

[0332] When the resin (D) is trimethylolpropane triacrylate (TMPTA), the resin (D) has a viscosity of 70 mPa·s or more and 80 mPa·s or less at 25°C. When the resin (D) is dipentaerythritol hexaacrylate (DPHA), the resin (D) has a viscosity of 5000 mPa·s or more and 10000 mPa·s or less. When the resin (D) is “M-9050”, the resin (D) has a viscosity of 6000 mPa·s or more and 14000 mPa·s or less.

[0333] <6.2. Content ratio of each resin in the entire photopolymerizable component>

[0334] Next, the content ratio of each resin in the entire photopolymerizable component according to the present embodiment will be described. In the present embodiment, the content ratio of the resin (A) relative to the entire photopolymerizable component is 20% by mass or more and 40% by mass or less. In addition, the total content ratio of the resin (A) and the resin (B) relative to the entire photopolymerizable component is preferably 50% by mass or more, more preferably 60% by mass or more. The total content ratio of the resin (A) and the resin (B) relative to the entire photopolymerizable component is 70% by mass or less. The total content ratio of the resin (A) and the resin (B) relative to the entire photopolymerizable component is preferably 50% by mass or more and 70% by mass or less, more preferably 60% by mass or more and 70% by mass or less.

[0335] In addition, the total content ratio of resin (B) and resin (C) relative to the entire photopolymerizable component is preferably 40% by mass or more, more preferably 50% by mass or more, and still more preferably 59% by mass or more. The total content ratio of resin (B) and resin (C) relative to the entire photopolymerizable component is preferably 70% by mass or less. The total content ratio of resin (B) and resin (C) relative to the entire photopolymerizable component may be 40% by mass or more and 70% by mass or less, preferably 50% by mass or more and 70% by mass or less, and still more preferably 59% by mass or more and 70% by mass or less.

[0336] In addition, the content ratio of resin (D) relative to the entire photopolymerizable component is preferably more than 0% by mass, more preferably more than 1% by mass. The content ratio of resin (D) relative to the entire photopolymerizable component is preferably 20% by mass or less, more preferably 10% by mass or less. The content ratio of resin (D) relative to the entire photopolymerizable component may be more than 0% by mass and 20% by mass or less, preferably more than 1% by mass and 20% by mass or less, and still more preferably more than 1% by mass and 10% by mass or less.

[0337] <6.3. Photoinitiator>

[0338] 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 alkyl phenone-based photoinitiator. As the photoinitiator, for example, “Irgacure819” manufactured by IGM Resins B.V. can be used.

[0339] In the imprintable photocurable acrylic resin, when the content ratio of the entire photopolymerizable component is 100% by mass, the content ratio of the photoinitiator is preferably 0.5% by mass or more, more preferably 1% by mass or more. In the imprintable photocurable acrylic resin, when the content ratio of the entire photopolymerizable component is 100% by mass, the content ratio of the photoinitiator is preferably 3% by mass or less. In the imprintable photocurable acrylic resin, when the content ratio of the entire photopolymerizable component is 100% by mass, the content ratio of the photoinitiator is preferably 0.5% by mass or more and 3% by mass or less, more preferably 1% by mass or more and 3% by mass or less.

[0340] <6.4. Viscosity of Imprintable Photocurable Acrylic Resin>

[0341] Next, the viscosity of the ultraviolet curable acrylic resin for imprinting according to the present embodiment will be described. According to the relationship of the content ratios of the resin (A), resin (B), resin (C), and resin (D) shown in the above 6.2., the viscosity of the ultraviolet curable acrylic resin for imprinting at 25°C is preferably 5 mPa·s or more. The viscosity of the ultraviolet curable acrylic resin for imprinting at 25°C may be 35 mPa·s or less, preferably 25 mPa·s or less, and more preferably 20 mPa·s or less. The viscosity of the ultraviolet curable acrylic resin for imprinting at 25°C may be 5 mPa·s or more and 35 mPa·s or less, preferably 5 mPa·s or more and 25 mPa·s or less, and more preferably 5 mPa·s or more and 20 mPa·s or less.

[0342] <6.5. YI value of the cured product of the ultraviolet curable acrylic resin for imprinting>

[0343] Next, the YI (Yellow Index) value of the cured product obtained by irradiating the ultraviolet curable acrylic resin for imprinting according to the present 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, for example, based on the measurement results using a 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, hue calculation is performed by software to calculate X, Y, and Z in the XYZ colorimetric system. 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.

[0344] YI = 100×(1.2985X - 1.1335Z) / Y…(3)

[0345] After the cured product of the ultraviolet curable acrylic resin for imprinting according to the present embodiment is held at 120°C for 500 hours, the YI value of the cured product is preferably 0 or more. After the cured product of the ultraviolet curable acrylic resin for imprinting is held at 120°C for 500 hours, the YI value of the cured product may be 3 or less, preferably 2.5 or less, and more preferably 2 or less. After the cured product of the ultraviolet curable acrylic resin for imprinting is held at 120°C for 500 hours, the YI value of the cured product may be 0 or more and 3 or less, preferably 0 or more and 2.5 or less, and more preferably 0 or more and 2 or less.

[0346] <Average transmittance of the cured product of the photocurable acrylic resin for imprinting>

[0347] Next, the average transmittance of the cured product of the photocurable acrylic resin for imprinting according to the present embodiment with respect to light 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, an ultraviolet-visible-near-infrared spectrophotometer V-770 manufactured by JASCO Corporation.

[0348] After the cured product of the photocurable acrylic resin for imprinting according to the present embodiment is held 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 680 nm or less can be 91% or more, preferably 92% or more. After the cured product of the photocurable acrylic resin for imprinting is held 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 680 nm or less can be 94% or less. After the cured product of the photocurable acrylic resin for imprinting is held 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 680 nm or less can be 91% or more and 94% or less, preferably 92% or more and 94% or less.

[0349] In addition, the difference in the average transmittance of the cured product of the photocurable acrylic resin for imprinting according to the present embodiment with respect to light in the wavelength range of 430 nm or more and 680 nm or less before and after being held at 120 °C for 500 hours (|average transmittance before holding - average transmittance after holding|) can be 0.0% or more. The difference in the average transmittance of the cured product of the photocurable acrylic resin for imprinting with respect to light in the wavelength range of 430 nm or more and 680 nm or less before and after being held at 120 °C for 500 hours (|average transmittance before holding - average transmittance after holding|) can be 0.5% or less, preferably 0.3% or less, more preferably 0.2% or less. The difference in the average transmittance of the cured product of the photocurable acrylic resin for imprinting with respect to light in the wavelength range of 430 nm or more and 680 nm or less before and after being held at 120 °C for 500 hours (|average transmittance before holding - average transmittance after holding|) can be 0.0% or more and 0.5% or less, preferably 0.0% or more and 0.3% or less, more preferably 0.0% or more and 0.2% or less.

[0350] After the cured product of the UV-curable acrylic resin for imprinting according to this embodiment is maintained 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 can be 90% or more, preferably 91% or more. After the cured product of the UV-curable acrylic resin for imprinting is maintained 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 can be 94% or less. After the cured product of the UV-curable acrylic resin for imprinting is maintained 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 can be 90% or more and 94% or less, preferably 91% or more and 94% or less.

[0351] In addition, the difference in the average transmittance of the cured product of the UV-curable acrylic resin for imprinting according to this embodiment with respect to light in the wavelength range of 430 nm or more and 510 nm or less before and after being maintained at 120 °C for 500 hours (|average transmittance before maintenance - average transmittance after maintenance|) can be 0.0% or more. The difference in the average transmittance of the cured product of the UV-curable acrylic resin for imprinting with respect to light in the wavelength range of 430 nm or more and 510 nm or less before and after being maintained at 120 °C for 500 hours (|average transmittance before maintenance - average transmittance after maintenance|) can be 1.2% or less, preferably 0.7% or less, more preferably 0.5% or less. The difference in the average transmittance of the cured product of the UV-curable acrylic resin for imprinting with respect to light in the wavelength range of 430 nm or more and 510 nm or less before and after being maintained at 120 °C for 500 hours (|average transmittance before maintenance - average transmittance after maintenance|) can be 0.0% or more and 1.2% or less, preferably 0.0% or more and 0.7% or less, more preferably 0.0% or more and 0.5% or less.

[0352] <6.7. Storage modulus of the cured product of the UV-curable acrylic resin for imprinting>

[0353] Next, the storage modulus of the cured product of the UV-curable acrylic resin for imprinting will be described. The storage modulus refers to the component of the energy generated by an external force and strain that is retained inside the object. That is, the storage modulus represents the hardness of the cured product. The larger the storage modulus, the harder the cured product. The storage modulus can be measured, for example, using DMA7100 manufactured by Hitachi High-Tech Corporation. For example, the cured product sheet can be cut into 20 mm in length and 3 mm in width, and in the tensile mode, the temperature can be increased at a certain frequency (1 Hz) at 5 °C / minute to measure the storage modulus at 25 °C to 300 °C.

[0354] The storage modulus of the cured product of the imprinting photocurable acrylic resin according to this embodiment at 30°C can be 1.6×10 9 Pa or more, preferably 2.0×10 9 Pa or more, more preferably 2.2×10 9 Pa or more. The storage modulus of the cured product of the imprinting photocurable acrylic resin at 30°C can be 2.5×10 9 Pa or less. The storage modulus of the cured product of the imprinting photocurable acrylic resin at 30°C can be 1.6×10 9 Pa or more and 2.5×10 9 Pa or less, preferably 2.0×10 9 Pa or more and 2.5×10 9 Pa or less, more preferably 2.2×10 9 Pa or more and 2.5×10 9 Pa or less.

[0355] The storage modulus of the cured product of the imprinting photocurable acrylic resin according to this embodiment at 120°C can be 3.9×10 8 Pa or more, preferably 6.0×10 8 Pa or more, more preferably 7.0×10 8 Pa or more. The storage modulus of the cured product of the imprinting photocurable acrylic resin at 120°C can be 2.5×10 9 Pa or less. The storage modulus of the cured product of the imprinting photocurable acrylic resin at 120°C can be 3.9×10 8 Pa or more and 2.5×10 9 Pa or less, preferably 6.0×10 8 Pa or more and 2.5×10 9 Pa or less, more preferably 7.0×10 8 Pa or more and 2.5×10 9 Pa or less.

[0356] The storage modulus of the cured product of the imprinting photocurable acrylic resin according to this embodiment at 130°C can be 3.1×10 8 Pa or more, preferably 5.5×10 8 Pa or more, more preferably 7.0×10 8 Pa or more. The storage modulus of the cured product of the imprinting photocurable acrylic resin at 130°C can be 2.5×10 9 Pa or less. The storage modulus of the cured product of the imprinting photocurable acrylic resin at 130°C can be 3.1×10 8 Pa or more and 2.5×10 9below Pa, preferably 5.5×10 8 above Pa and below 2.5×10 9 Pa, and more preferably above 7.0×10 8 above Pa and below 2.5×10 9 Pa.

[0357] The storage modulus of the cured product of the imprinting photocurable acrylic resin according to this embodiment at 140°C can be 2.6×10 8 Pa or more, preferably 5.0×10 8 Pa or more, and more preferably 6.0×10 8 Pa or more. The storage modulus of the cured product of the imprinting photocurable acrylic resin at 140°C can be 2.5×10 9 Pa or less. The storage modulus of the cured product of the imprinting photocurable acrylic resin at 140°C can be 2.6×10 8 above Pa and below 2.5×10 9 Pa, preferably 5.0×10 8 above Pa and below 2.5×10 9 Pa, and more preferably 6.0×10 8 above Pa and below 2.5×10 9 Pa.

[0358] In addition, the change rate of the storage modulus of the cured product at 120°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 120°C / storage modulus at 30°C × 100%) can be 17% or more, preferably 30% or more, more preferably 40% or more. The change rate of the storage modulus of the cured product at 120°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 120°C / storage modulus at 30°C × 100%) can be 100% or less. The change rate of the storage modulus of the cured product at 120°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 120°C / storage modulus at 30°C × 100%) can be 17% or more and 100% or less, preferably 30% or more and 100% or less, more preferably 40% or more and 100% or less.

[0359] The rate of change of the storage modulus of the cured product at 130°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 130°C / storage modulus at 30°C × 100%) can be 14% or more, preferably 27% or more, more preferably 33% or more. The rate of change of the storage modulus of the cured product at 130°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 130°C / storage modulus at 30°C × 100%) can be 100% or less. The rate of change of the storage modulus of the cured product at 130°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 130°C / storage modulus at 30°C × 100%) can be from 14% to 100%, preferably from 27% to 100%, more preferably from 33% to 100%.

[0360] The rate of change of the storage modulus of the cured product at 140°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 140°C / storage modulus at 30°C × 100%) can be 11% or more, preferably 25% or more, more preferably 30% or more. The rate of change of the storage modulus of the cured product at 140°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 140°C / storage modulus at 30°C × 100%) can be 100% or less. The rate of change of the storage modulus of the cured product at 140°C with respect to the storage modulus of the cured product at 30°C (storage modulus at 140°C / storage modulus at 30°C × 100%) can be from 11% to 100%, preferably from 25% to 100%, more preferably from 30% to 100%.

[0361] <6.8. Glass transition temperature Tg of the cured product of the photo-curable acrylic resin for imprinting>

[0362] Next, the glass transition temperature Tg of the cured product of the photo-curable acrylic resin for imprinting will be described. The glass transition temperature Tg can be measured, for example, using DMA7100 manufactured by Hitachi High-Technologies Corporation. For example, a sheet of the cured product can be cut into a size of 20 mm in length × 3 mm in width, and in the tensile mode, the temperature can be increased at a rate of 5°C per minute at a certain frequency (1 Hz), and the maximum value of the loss tangent tanδ at 25°C to 300°C can be confirmed for measurement.

[0363] The glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprinting according to this embodiment may be 115°C or higher, preferably 140°C or higher, and more preferably 170°C or higher. The glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprinting may be 185°C or lower. The glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprinting may be from 115°C to 185°C, preferably from 140°C to 185°C, and more preferably from 170°C to 185°C.

[0364] <6.9. Effects of the photocurable acrylic resin for imprinting>

[0365] As described above, the photocurable acrylic resin for imprinting according to this embodiment contains resin (A). Thereby, the heat resistance of the cured product of the photocurable acrylic resin for imprinting can be improved.

[0366] The photocurable acrylic resin for imprinting according to this embodiment contains resin (B) having a viscosity of 10 mPa·s or less at 25°C. Thereby, the viscosity of the photocurable acrylic resin for imprinting according to this embodiment can be reduced. In addition, resin (B) is preferably a bifunctional acrylate monomer in which acryloyl groups are respectively bonded to both ends of a linear structure composed of hydrocarbon groups, or a bifunctional acrylate monomer in which acryloyl groups are respectively bonded to both ends of a linear structure having an ether bond. Thereby, the viscosity of the photocurable acrylic resin for imprinting can be further reduced. In addition, resin (B) is a bifunctional acrylate monomer represented by the above chemical formula (I), and in the chemical formula (I), n is preferably an integer of 1 or more and 9 or less. Thereby, the viscosity of the photocurable acrylic resin for imprinting can be further reduced. In addition, resin (B) is a bifunctional acrylate monomer represented by the above chemical formula (I), and in the chemical formula (I), n is preferably an integer of 6 or more and 9 or less. Thereby, the viscosity of the photocurable acrylic resin for imprinting can be further reduced. In addition, resin (B) is a bifunctional acrylate monomer represented by the above chemical formula (I), and in the chemical formula (I), n is preferably an integer of 6 or 9. Thereby, the viscosity of the photocurable acrylic resin for imprinting can be further reduced.

[0367] The photocurable acrylic resin for imprinting according to this embodiment preferably further contains a resin (C) having a viscosity of 10 mPa·s or less at 25°C. Thereby, the viscosity of the photocurable acrylic resin for imprinting according to this embodiment can be further reduced. In addition, in this embodiment, the resin (C) is preferably an acrylate monomer having a viscosity of 10 mPa·s or less at 25°C and being structurally hard. Thereby, the viscosity of the photocurable acrylic resin for imprinting according to this embodiment can be further reduced and the heat resistance of the cured product of the photocurable acrylic resin for imprinting can be further improved. In addition, the resin (C) is preferably a monofunctional acrylate monomer. Thereby, in the polymerization reaction (curing reaction) of the photocurable acrylic resin for imprinting, the reaction at the end of the polymer can be terminated. Therefore, deterioration starting from the end groups of the cured product (polymer) of the photocurable acrylic resin for imprinting can be suppressed. In addition, the resin (C) is preferably isobornyl acrylate. Thereby, the viscosity of the photocurable acrylic resin for imprinting according to this embodiment can be further reduced and the heat resistance of the cured product of the photocurable acrylic resin for imprinting can be further improved.

[0368] The photocurable acrylic resin for imprinting according to this embodiment preferably further contains a polyfunctional acrylate monomer having three or more functional groups, i.e., a resin (D). Thereby, the photocurable acrylic resin for imprinting according to this embodiment can increase the crosslinking density during curing, can further improve the heat resistance of the cured product of the photocurable acrylic resin for imprinting, and can suppress a decrease in the storage modulus at high temperatures. In addition, the resin (D) is preferably one or more selected from the group consisting of trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and polyfunctional polyester acrylate. Thereby, the heat resistance of the cured product of the photocurable acrylic resin for imprinting can be further improved.

[0369] In addition, as described above, in the photocurable acrylic resin for imprinting according to this embodiment, the content ratio of the resin (A) relative to the entire photopolymerizable component is 20% by mass or more and 40% by mass or less, and the total content ratio of the resin (A) and the resin (B) relative to the entire photopolymerizable component is 70% by mass or less. Thereby, the photocurable acrylic resin for imprinting according to this embodiment can achieve both low viscosity and an improvement in the heat resistance of the cured product.

[0370] Since the photocurable acrylic resin for imprinting according to this embodiment has a low viscosity, it is possible to perform the above-described nanoimprinting step S12 ( Figure 11) so that the thickness (layer thickness) of the layer of the imprinting photocurable acrylic resin (organic material) becomes uniform when the master disk 60 is pressed thereon. Thereby, it is possible to make the peeling force applied when peeling the master disk 60 from the cured layer of the imprinting photocurable acrylic resin uniform in the plane. Therefore, it is possible to avoid the situation where the cured layer of the imprinting photocurable acrylic resin peels off from the substrate 10. Therefore, it is possible to suppress the residue of the cured layer of the imprinting photocurable acrylic resin on the master disk 60, and the master disk 60 can be reused. In addition, since the above peeling force can be made uniform in the plane, it is possible to avoid the situation where the fine concavo-convex shape transferred to the cured layer of the imprinting photocurable acrylic resin is deformed when the master disk 60 is peeled off. Therefore, it is possible to suppress the deterioration of the optical characteristics caused by the fine concavo-convex shape of the cured product of the imprinting photocurable acrylic resin. Therefore, in the case of manufacturing the grating structure 20 from the cured product of the imprinting photocurable acrylic resin, it is possible to suppress the deterioration of the polarization characteristics of the grating structure 20.

[0371] In addition, since the imprinting photocurable acrylic resin according to the present embodiment has a low viscosity, in the above nanoimprinting step S12, it is possible to improve the followability of the imprinting photocurable acrylic resin to the fine concavo-convex shape of the master disk 60 when the master disk 60 is pressed onto the imprinting photocurable acrylic resin. Therefore, in the above nanoimprinting step S12, the fine concavo-convex shape of the master disk 60 can be transferred over the layer of the imprinting photocurable acrylic resin.

[0372] In addition, since the imprinting photocurable acrylic resin according to the present embodiment has a low viscosity, in the above nanoimprinting step S12, it is possible to suppress the mixing of air bubbles into the imprinting photocurable acrylic resin. Thereby, it is possible to avoid the situation where a part of the fine concavo-convex shape is interrupted by air bubbles in the cured product of the imprinting photocurable acrylic resin. Therefore, in the case of manufacturing the grating structure 20 from the cured product of the imprinting photocurable acrylic resin, it is possible to suppress the disconnection of the ridge portion 22 of the grating structure 20.

[0373] The cured product of the imprinting photocurable acrylic resin according to the present embodiment has excellent heat resistance. Therefore, in the case of manufacturing an optical material (for example, the grating structure 20 of the above wire grid polarizing element 1) from the cured product of the imprinting photocurable acrylic resin, even when heat treatment such as vapor deposition is performed on the optical material, it is possible to suppress the deterioration of the optical characteristics of the optical material.

[0374] For example, since the cured product of the ultraviolet curable acrylic resin for imprinting according to the present embodiment has excellent heat resistance, after the cured product of the ultraviolet curable acrylic resin for imprinting is held at 120° C. for 500 hours, the YI value of the cured product is 3 or less. Therefore, by manufacturing an optical material from the cured product of the ultraviolet curable acrylic resin for imprinting, even when the optical material is subjected to a heat treatment such as vapor deposition, yellowing of the optical material can be suppressed and transparency can be maintained.

[0375] In addition, since the cured product of the ultraviolet curable acrylic resin for imprinting according to the present embodiment has excellent heat resistance, after the cured product of the ultraviolet curable acrylic resin for imprinting is held 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 680 nm or less is 91% or more. Therefore, by manufacturing an optical material from the cured product of the ultraviolet curable acrylic resin for imprinting, even when the optical material is subjected to a heat treatment such as vapor deposition, the average transmittance of the optical material with respect to light in the above wavelength region can be maintained at a high level.

[0376] In addition, since the cured product of the ultraviolet curable acrylic resin for imprinting according to the present embodiment has excellent heat resistance, after the cured product of the ultraviolet curable acrylic resin for imprinting is held 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 ultraviolet curable acrylic resin for imprinting, even when the optical material is subjected to a heat treatment such as vapor deposition, the average transmittance of the optical material with respect to light in the above wavelength range can be maintained at a high level.

[0377] In addition, the storage modulus of the cured product of the ultraviolet curable acrylic resin for imprinting at 30° C. is preferably 1.6×10 9 Pa or more. Thereby, in the above nanoimprinting step S12( Figure 11 ), the situation where the fine concavo-convex shape transferred to the layer of the cured ultraviolet curable acrylic resin for imprinting is deformed when the master disk 60 is peeled off can be avoided. Therefore, a decrease in optical characteristics caused by the fine concavo-convex shape of the cured product of the ultraviolet curable acrylic resin for imprinting can be further suppressed. Therefore, when manufacturing the grid structure 20 from the cured product of the ultraviolet curable acrylic resin for imprinting, a decrease in the polarization characteristics of the grid structure 20 can be further suppressed.

[0378] In addition, since the cured product of the ultraviolet curable acrylic resin for imprinting according to the present embodiment has excellent heat resistance, the storage modulus of the cured product at 120° C. is 3.9×10 8Pa or more. Therefore, by manufacturing an optical material from the cured product of the imprintable photocurable acrylic resin, even when a heat treatment such as vapor deposition is performed on the optical material, deformation of the optical material can be further suppressed. Thus, a decrease in the optical properties of the optical material can be more suppressed.

[0379] In addition, as described above, when manufacturing the wire grid polarizing element 1, a reflective film 30 is vapor-deposited on the grid structure 20. The grid structure 20 is heated during the vapor deposition of the reflective film 30. Here, if the heat resistance of the grid structure 20 is low, there is a problem that the grid structure 20 deforms and the polarization characteristics deteriorate during the vapor deposition of the reflective film 30.

[0380] However, the cured product of the imprintable photocurable acrylic resin according to the present embodiment has excellent heat resistance. Therefore, by manufacturing the grid structure 20 from the cured product of the imprintable photocurable 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 suppressed. In addition, 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 at a high level. Thus, a decrease in the polarization characteristics of the grid structure 20 can be further suppressed.

[0381] In addition, as described above, the viscosity of the photocurable acrylic resin for imprinting in the light-polymerizable component at 25°C is preferably 35 mPa·s or less. Thereby, in the nanoimprinting step S12, the thickness of the layer of the photocurable acrylic resin for imprinting when pressing the master disk 60 on the photocurable acrylic resin for imprinting becomes more uniform, the followability of the photocurable acrylic resin for imprinting to the fine concavo-convex shape of the master disk 60 can be further improved, and the mixing of air bubbles into the photocurable acrylic resin for imprinting can be further suppressed.

[0382] In addition, as described above, in the photocurable acrylic resin for imprinting according to the present embodiment, the total content ratio of resin (B) and resin (C) with respect to the entire light-polymerizable component is preferably 50% by mass or more and 70% by mass or less. Thereby, the viscosity of the photocurable acrylic resin for imprinting according to the present embodiment can be further reduced. For example, by setting the total content ratio of resin (B) and resin (C) with respect to the entire light-polymerizable component to 59% by mass or more and 70% by mass or less, the viscosity of the photocurable acrylic resin for imprinting in the light-polymerizable component at 25°C can be made 25 mPa·s or less.

[0383] In addition, as described above, in the photocurable acrylic resin for imprinting according to the present embodiment, the content ratio of the resin (D) relative to the whole of the photopolymerizable components is preferably more than 0% by mass and 20% by mass or less. Thereby, the heat resistance of the photocurable acrylic resin for imprinting according to the present embodiment can be further improved. For example, the storage modulus of the cured product of the photocurable acrylic resin for imprinting at 120°C can be 6.2×10 8 Pa or more, the storage modulus of the cured product of the photocurable acrylic resin for imprinting at 130°C can be 5.5×10 8 Pa or more, and the storage modulus of the cured product of the photocurable acrylic resin for imprinting at 140°C can be 5.0×10 8 Pa or more. In addition, the change rate of the storage modulus of the cured product at 120°C relative to the storage modulus of the cured product at 30°C can be 30% or more, the change rate of the storage modulus of the cured product at 130°C relative to the storage modulus of the cured product at 30°C can be 27% or more, and the change rate of the storage modulus of the cured product at 140°C relative to the storage modulus of the cured product at 30°C can be 23% or more. In addition, the glass transition temperature of the cured product of the photocurable acrylic resin for imprinting can be 125°C or more.

[0384] <6.10. Other components>

[0385] In the photocurable acrylic resin for imprinting, other components (additives) may be contained within a range that does not interfere with the effects shown in 6.9. above. Other components include, for example, antioxidants, phosphors, plasticizers, ultraviolet absorbers, defoamers, thixotropic agents, polymerization inhibitors, mold release agents, particles of metal oxides, etc.

[0386]

Examples

[0387] Next, examples of the present invention will be described. However, the examples described below are specific examples illustrated to explain the structure, 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.

[0388] <1. Verification results of transmissivity and polarization separation characteristics with respect to obliquely incident light>

[0389] As an embodiment of the present invention, a model of the wire grid polarizing element 1 according to the above-described embodiment was fabricated, and the wire grid polarizing element 1 was evaluated by simulating its various characteristics. In addition, in order to compare with the embodiment of the present invention, a model of the wire grid polarizing element according to the prior art example was also fabricated, and simulation and evaluation were similarly performed. In addition, for the sake of convenience in explanation hereinafter, the same reference signs and numerals are assigned to the reference signs indicating the structural elements (substrate 10, grid structure body 20, base portion 21, rib portion 22, reflection film 30, etc.) of the polarizing element and the numerals indicating various dimensions of these structural elements in both the embodiment and the prior art example.

[0390] In addition, the numerals indicating various dimensions and the like of the polarizing element 1 used in the following description are explained as follows.

[0391] P: Pitch of the rib portion 22

[0392] W T : Width of the top of the rib portion 22 (width of the rib top)

[0393] W M : Width at the central position in the height direction of the rib portion 22 (width of the rib center)

[0394] W B : Width of the bottom of the rib portion 22 (width of the grid bottom)

[0395] W MAX : Maximum width of the reflection film 30 covering the rib portion 22 (width of the grid maximum)

[0396] H: Height of the rib portion 22

[0397] Hx: Height of the portion of the side surface 22b of the rib portion 22 covered by the reflection film 30

[0398] Dt: Thickness of the reflection film 30 covering the front end 22a of the rib portion 22 (front end thickness of the reflection film 30)

[0399] Ds: Thickness of the reflection film 30 covering the side surface 22b of the rib portion 22 (side surface thickness of the reflection film 30)

[0400] Rc: Coverage rate of the side surface 22b of the rib portion 22 covered by the reflection film 30

[0401] Rr: Opening rate of the side surface 22b of the rib portion 22 covered by the reflection film 30

[0402] θ: Incident angle of incident light

[0403] λ: Wavelength of incident light

[0404] (Prior art example 1)

[0405] First, an existing example 1 will be described with reference to Figure 18 the following.

[0406] As Figure 18 shown in (a) of

[0407] a model of the polarization element 1 according to the existing example 1 was fabricated. The polarization element 1 according to the existing example 1 includes: a glass substrate 10 and a grid structure body 20 made of an ultraviolet curable resin (acrylic resin). The grid structure body 20 has: a base portion 21 provided along the surface of the substrate 10 and a plurality of protruding strip portions 22 protruding in a lattice shape from the base portion 21. The cross-sectional shape of the protruding strip portion 22 is rectangular and not tapered. The reflective film 30 covering the protruding strip portion 22 is an Al film. The reflective film 30 is formed so as to cover the entire front end 22a and one side surface 22b of the protruding strip portion 22 and a part of the base portion 21. However, the reflective film 30 does not completely cover the other side surface 22b of the protruding strip portion 22. Thus, the reflective film 30 of the existing example 1 is formed only on one side of the protruding strip portion 22, and the other side of the protruding strip portion 22 is not covered with the reflective film 30 and is open.

[0408] P: 144 nm

[0409] W T : 32.5 nm

[0410] W B : 32.5 nm

[0411] W MAX : 55 nm

[0412] H: 220 nm

[0413] Hx: 220 nm (one side), 0 nm (the other side)

[0414] Dt: 35 nm

[0415] Ds: 22.5 nm (maximum value)

[0416] Rc: 100% (one side), 0% (the other side)

[0417] Rr: 0% (one side), 100% (the other side)

[0418] θ: 0° to +60°

[0419] λ: 430 to 680 nm

[0420] Then, for the model of the polarization element 1 related to the existing example 1 fabricated in the above-described manner, the incident angle θ was changed to perform simulations, and the transmittance (Tp) of the transmission axis, the reflectance (Rs) of the reflection axis, and Tp×Rs required for the polarization beam splitter (PBS) were calculated respectively. The incident angle θ was from 0° to +60°. In addition, as the values of Tp and Rs, the average values of a plurality of Tp and Rs values calculated by changing the wavelength λ of the incident light in the range of 430 to 680 nm and for the incident light of each wavelength λ were used. The relationships between Tp, Rs, and Tp×Rs calculated in the above-described manner and θ are shown in Figure 18 the curve graphs of (b) to (d).

[0421] As Figure 18 shown, in the existing example 1, the reflective film 30 is biased toward the side of the convex strip portion 22, and the coverage rate Rc on this side is 100%. Therefore, the larger the incident angle θ, the more gradually Rs increases, while Tp decreases significantly, so Tp×Rs also decreases significantly. For example, in the range where θ > 45°, Tp decreases to 76% or less, and Tp×Rs decreases to 68% or less. Therefore, it can be known that when using the polarization element 1 related to the existing example 1 as a polarization beam splitter, especially for obliquely incident light with a large incident angle θ of 45° or more, the polarization separation characteristic (Tp×Rs characteristic) is poor, and there is a problem that the Tp×Rs characteristic required for the polarization beam splitter cannot be obtained.

[0422] (Existing Example 2)

[0423] Next, the existing example 2 will be described with reference to Figure 19 .

[0424] As Figure 19 shown in (a) of, a model of the polarization element 1 related to the existing example 2 was fabricated. The model of the existing example 2 is the same as the model of the above-described existing example 1. However, in the existing example 2, as the incident angle θ, two directions were used: the incident angle in the + direction obliquely incident on one side of the convex strip portion 22 (θ = 0° to +60°) and the incident angle in the - direction obliquely incident on the other side of the convex strip portion 22 (θ = 0° to -60°).

[0425] The dimensions and shapes of the respective parts of the model of the polarization element 1 related to the existing example 2 are as follows.

[0426] P: 144 nm

[0427] W T : 32.5 nm

[0428] W B : 32.5 nm

[0429] W MAX : 55 nm

[0430] H: 220 nm

[0431] Hx: 220 nm (one side), 0 nm (the other side)

[0432] Dt: 35 nm

[0433] Ds: 22.5 nm (maximum value)

[0434] Rc: 100% (one side), 0% (the other side)

[0435] Rr: 0% (one side), 100% (the other side)

[0436] θ: 0° to +60°, 0° to -60°

[0437] λ: 430 to 680 nm

[0438] Then, for the model of the polarization element 1 related to the existing example 2 fabricated in the above-described manner, the incident angle θ was changed to perform simulation, and the transmittance (Tp) of the transmission axis, the reflectance (Rs) of the reflection axis, and Tp×Rs required for the polarization beam splitter (PBS) were calculated respectively. At this time, for each of the cases where the incident angle θ is in the + direction and the - direction, Tp, Rs, and Tp×Rs were calculated. In addition, as the values of Tp and Rs, the average values of a plurality of Tp and Rs values calculated by changing the wavelength λ of the incident light in the range of 430 to 680 nm and for each wavelength of the incident light were used. The relationships between Tp, Rs, Tp×Rs and θ calculated in the above-described manner are shown in Figure 19 the graphs of (b) to (d).

[0439] As Figure 19 shown, in the existing example 2, similar to the above-described existing example 1, the reflection film 30 is biased toward one side of the convex strip portion 22, and the coverage rate Rc of this side is 100%. As a result, as Figure 19 shown in (b) of, in the existing example 2, similar to the above-described existing example 1, for the incidence of obliquely incident light from the + direction, the larger the incident angle θ, the more significantly Tp(+) decreases. Moreover, in the existing example 2, for the incidence of obliquely incident light from the - direction, the larger the absolute value of the negative incident angle θ, the more Tp(-) decreases, but it can be confirmed that the degree of decrease of Tp(-) is smaller than that of Tp(+).

[0440] Specifically, in the existing example 2, in the range where the absolute value of θ is 30° to 60°, the difference between Tp(+) and Tp(-) is 5% or more, and the difference between Tp×Rs(+) and Tp×Rs(-) is 4% or more. Based on this result, in the existing example 2, it can be confirmed that there is left-right asymmetry in the polarization characteristics of the polarization element 1 depending on whether the incident direction of the obliquely incident light is in the + direction or the - direction.

[0441] As in the above-described Existing Example 2, it is known that when the difference in Tp caused by the difference in the incident direction of the obliquely incident light (for example, the difference between +45° and -45°) becomes large, the observer can recognize the difference in the brightness of the displayed image. In addition, there is also a problem that it is not suitable as an image state. Further, it is also known that when the polarization element 1 according to Existing Example 2 is used as a polarization beam splitter, particularly with respect to obliquely incident light having a large incident angle θ of 45° or more, the polarization separation characteristics (Tp×Rs characteristics) are poor, and there is also a problem that the Tp×Rs characteristics required for a polarization beam splitter cannot be obtained.

[0442] (Existing Example 3)

[0443] Next, Existing Example 3 will be described with reference to Figure 20 that.

[0444] As Figure 20 (a) of shows, a model of the polarization element 1 according to Existing Example 3 was fabricated. The polarization element 1 according to Existing Example 3 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 protruding portions 22 protruding in a lattice shape from the base portion 21. The cross-sectional shape of the protruding portion 22 is rectangular, not tapered. The reflective film 30 covering the protruding portion 22 is an Al film. The reflective film 30 is formed so as to cover most (about 85%) of the front end 22a and both side surfaces 22b of the protruding portion 22. Thus, the reflective film 30 of Existing Example 3 covers most of the front end 22a and both side surfaces 22b of the protruding portion 22. In addition, the reflective film 30 of Existing Example 3 is angular and has two corner portions with sharp corners at the left and right ends of the top of the reflective film 30, which is different from the rounded bulging shape of the reflective film 30 of the polarization element 1 according to the present embodiment described above.

[0445] The dimensions and shapes of the respective parts of the model of the polarization element 1 according to Existing Example 3 are as follows.

[0446] P: 140 nm

[0447] W T : 35 nm

[0448] W B : 35 nm

[0449] W MAX : 65 nm

[0450] H: 230 nm

[0451] Hx: 196 nm

[0452] Dt: 30 nm

[0453] Ds: 15 nm (maximum)

[0454] Rc: 85%

[0455] Rr: 15%

[0456] θ: 0° to +60°

[0457] λ: 430 to 680 nm

[0458] Then, for the model of the polarization element 1 related to the existing example 3 produced in the above-described manner, similar to the above-described existing example 1, the incident angle θ was changed to perform simulation, and Tp, Rs, and Tp×Rs were calculated respectively. The incident angle θ was 0° to +60°. The relationships between Tp, Rs, and Tp×Rs thus calculated and θ are shown in Figure 20 (b) to (d) of the graphs.

[0459] As Figure 20 shown, in the existing example 3, compared with the above-described existing example 1, the covering method is different, but the reflective film 30 covers most of the two side surfaces 22b of the protruding strip portion 22, and its coverage rate Rc is as large as 85%. Therefore, in the existing example 3, similar to the above-described existing example 1, as the incident angle θ increases, Rs gradually increases, while Tp significantly decreases, so Tp×Rs also significantly decreases. For example, in the range where θ > 45°, Tp drops below 73%, and Tp×Rs drops below 65%. Therefore, it can be known that when the polarization element 1 related to the existing example 3 is used as a polarization beam splitter, especially for obliquely incident light with a large incident angle θ of more than 45°, the polarization separation characteristic (Tp×Rs characteristic) is poor, and there is a problem that the Tp×Rs characteristic required for the polarization beam splitter cannot be obtained.

[0460] (Example 1)

[0461] Next, the first embodiment of the present invention will be described with reference to Figure 21 and Figure 22 .

[0462] As Figure 21 shown in (a) of, a model of the polarization element 1 related to the first embodiment was produced. The polarization element 1 related to the first embodiment includes: a substrate 10 made of glass and a grid structure body 20 made of an ultraviolet curable resin (acrylic resin). The grid structure body 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 lattice shape. The cross-sectional shape of the protruding strip portion 22 is trapezoidal, and it is a head-thin shape that becomes thinner toward the front end 22a of the protruding strip portion 22.

[0463] The reflective film 30 covering the ribbed convex portion 22 in Example 1 is an Al film. The reflective film 30 is formed so as to cover the front end 22a of the ribbed convex portion 22 and the upper sides of the two side surfaces 22b. However, the reflective film 30 does not cover the lower sides and the base portion 21 of the two side surfaces 22b of the ribbed convex portion 22. The coverage rate Rc of the two side surfaces 22b of the ribbed convex portion 22 covered by the reflective film 30 is 40%. Thus, the reflective film 30 in Example 1 roundly wraps the top of the ribbed convex portion 22 (the front end 22a and the upper sides of the side surfaces 22b). The surface of the reflective film 30 has a substantially elliptical shape with a circular shape that bulges outward, and bulges in the width direction (X direction) of the ribbed convex portion 22.

[0464] As a result, the grid (the structure formed by the ribbed convex portion 22 and the reflective film 30) according to Example 1 has the above-described special tree shape. The maximum width W MAX (the width of the grid in the portion where the reflective film 30 bulges the most) is greater than or equal to the width W B (the width of the ribbed convex portion 22 at the height position 20% above the bottom of the ribbed convex portion 22).

[0465] The dimensions and shapes of the respective parts of the model of the polarization element 1 according to Example 1 are as follows.

[0466] P: 144 nm

[0467] W T : 19 nm

[0468] W M : 32.5 nm

[0469] W B : 46 nm

[0470] W MAX : 55 nm

[0471] H: 220 nm

[0472] Hx: 99 nm

[0473] Dt: 35 nm (maximum value)

[0474] Ds: 22.5 nm (maximum value)

[0475] Rc: 40%

[0476] Rr: 60%

[0477] θ: 0° to +60°

[0478] λ: 430 to 680 nm

[0479] Then, for the model of the polarization element 1 related to Example 1 fabricated in the above-described manner, the incident angle θ was changed to perform simulations, and the transmittance (Tp) of the transmission axis, the reflectance (Ts) of the transmission axis, the transmittance (Rp) of the reflection axis, the reflectance (Rs) of the reflection axis, and Tp×Rs required for the polarization beam splitter (PBS) were calculated respectively. The incident angle θ was from 0° to +60°. In addition, as the values of Tp, Rs, Ts, and Rp, the average values of a plurality of Tp, Ts, Rp, and Rs values calculated by varying the wavelength λ of the incident light in the range of 430 to 680 nm and for the incident light of each wavelength λ were used. In addition, the contrast ratio (CR) of the transmitted light (CR = Tp / Ts) was also calculated by dividing the transmittance (Tp) of the transmission axis by the reflectance (Ts) of the transmission axis.

[0480] The relationships between Tp, Rs, Ts, Rp, CR, and Tp×Rs calculated in the above-described manner and λ are shown in the table of (b) of ​ and the curve graphs of (c) to (d) of ​ In addition, the relationships between Tp, Rs, and Tp×Rs calculated in the above-described manner and θ are shown in the curve graphs of (a) to (c) of ​ In addition, in the curve graphs of (a) to (c) of

[0481] In addition, ​ in the table of (b) of ​ multiple wavelength ranges of the incident light (430 to 510 nm, 520 to 590 nm, 600 to 680 nm) and the entire wavelength range of the incident light (430 to 680 nm) are divided, and the average values of the respective characteristic values (Tp, Rs, Ts, Rp, CR, Tp×Rs) are shown. ​ In the curve graphs of (c) to (d) of ​ and the curve graphs of (a) to (c) of

[0482] As ​ shown in (a) of in the model of the polarization element 1 of Example 1, the reflective film 30 covers the top of the rib portion 22 and exposes the bottom of the rib portion 22, and the coverage rate Rc is 40%. Therefore, the grating (the structure formed by combining the rib portion 22 and the reflective film 30) of Example 1 has the above-described special tree shape. The grating of Example 1 having the special tree structure has excellent transmissivity and polarization separation characteristics with respect to obliquely incident light at a large and wide range of incident angles θ.

[0483] Therefore, it can be seen that as ​ shown, in Example 1, regardless of the wavelength λ, Tp is 80% or more and Rs is 90% or more, and high Tp and Rs can be obtained. As a result, it can be seen that Tp × Rs also becomes 72% or more, and excellent Tp × Rs characteristics can be obtained. In addition, it can also be seen that the contrast ratio CR is excellent at 100 or more regardless of the wavelength λ. Therefore, it can be seen that compared with the above-described conventional Examples 1 and 2, Example 1 can obtain good polarization characteristics with respect to obliquely incident light.

[0484] Moreover, as ​ shown, in Example 1, in a wide range where the incident angle θ is 0° to 60°, a very high value of Tp of 78% or more is ensured. As a result, it can be seen that with respect to obliquely incident light having a large and wide range (30° to 60°) of the incident angle θ, a high Tp × Rs of 73% or more can be ensured, and excellent polarization separation characteristics (Tp × Rs characteristics) are obtained. In particular, when θ = 45°, the value of Tp is very high at 87%, and the value of Tp × Rs is also very high at 78%. From this, it can be seen that the polarization element 1 of Example 1 can exhibit significantly excellent transmittance and polarization separation characteristics with respect to obliquely incident light having an incident angle θ of 45° and its vicinity.

[0485] Moreover, from the comparison result between Example 1 and Conventional Example 2 shown by ​ it can be seen that in Conventional Example 2, as the incident angle θ increases, Tp and Tp × Rs decrease, and in particular, in the range where θ > 45°, Tp and Tp × Rs decrease rapidly. In contrast, in Example 1, even when θ increases, the decrease in Tp and Tp × Rs is suppressed, and high values can be maintained. In particular, when θ = 45°, Example 1 can obtain Tp and Tp × Rs that are 6% or more higher than those in the case of incident light in the + direction of Conventional Example 2, and can obtain Tp and Tp × Rs that are 10% or more higher than those in the case of incident light in the - direction of Conventional Example 2. Thus, in Example 1, when θ = 45°, the highest transmittance (transmittance Tp) and Tp × Rs characteristics can be obtained.

[0486] In addition, regarding the reflectance Rs of the reflection axis, compared with Conventional Examples 1 and 2, Example 1 can obtain a high reflectance with no significant difference.

[0487] In addition, regarding the Tp×Rs characteristics required for a polarization beam splitter (PBS), Example 1 is superior to Conventional Examples 1 and 2. When the incident angle θ = 45°, the highest Tp×Rs characteristics can be obtained. In addition, even within the range of the incident angle θ = 30° to 60°, Example 1 can obtain better characteristics than Conventional Examples 1 and 2. For obliquely incident light with a large and wide range of incident angles θ, the Tp×Rs characteristics are superior to those of Conventional Examples 1 and 2. Moreover, in Example 1, for obliquely incident light with an incident angle θ within the range of 45° ± 15°, the balance of the Tp×Rs characteristics is good. Therefore, when the polarization element 1 according to Example 1 is used as a polarization beam splitter to project an image, from the perspective of an observer, the balance of the brightness of the displayed image is good, and the image state is also good.

[0488] As can be seen, when the polarization element 1 according to Example 1 is used as a polarization beam splitter, for obliquely incident light with a large and wide range of incident angles θ from 30° to 60°, especially for obliquely incident light with an incident angle of 45°, the transmissivity of the P-polarized light (transmittance Tp) and the polarization separation characteristics (Tp×Rs characteristics) are significantly superior. Therefore, it can be said that the polarization separation characteristics required for a polarization beam splitter can be fully satisfied for obliquely incident light.

[0489] In addition, regarding the contrast ratio CR of the transmitted light (CR = Tp / Ts), it can be seen that in Example 1, an excellent contrast ratio CR of 100 or more can be obtained.

[0490] (Example 2)

[0491] Next, refer to ​ to describe Example 2 of the present invention.

[0492] As ​ shown in (a) of, a model of the polarization element 1 according to Example 2 was fabricated. Compared with the model of the above-mentioned Example 1, the shape of the convex strip portion 22 and the covering manner realized by the reflective film 30 are different. The cross-sectional shape of the convex strip portion 22 in Example 2 is triangular, and it is a shape with a thinner head that becomes thinner as it approaches the front end 22a of the convex strip portion 22.

[0493] The reflective film 30 covering the rib portion 22 in Example 2 is an Al film. The reflective film 30 is formed so as to cover the front end 22a of the rib portion 22 and the upper sides of the two side surfaces 22b. However, the reflective film 30 does not cover the lower sides and the base portion 21 of the two side surfaces 22b of the rib portion 22. The coverage rate Rc of the two side surfaces 22b of the rib portion 22 covered by the reflective film 30 is 45%. Thus, the reflective film 30 in Example 2 circularly covers the top portion (the front end 22a and the upper sides of the side surfaces 22b) of the rib portion 22. The surface of the reflective film 30 has a substantially elliptical shape with a circular shape that bulges outward and bulges in the width direction (X direction) of the rib portion 22. Thus, the grating (the structure formed by combining the rib portion 22 and the reflective film 30) according to Example 2 has the above-described special tree shape as in Example 1.

[0494] The dimensions and shapes of the respective parts of the model of the polarization element 1 according to Example 2 are as follows.

[0495] P: 140 nm

[0496] W T : 10 nm

[0497] W B : 40 nm

[0498] W MAX : 41 nm

[0499] H: 230 nm

[0500] Hx: 103.5 nm

[0501] Dt: 50 nm (maximum value)

[0502] Ds: 17 nm (maximum value)

[0503] Rc: 45%

[0504] Rr: 55%

[0505] θ: 0° to +60°

[0506] λ: 430 to 680 nm

[0507] Then, for the model of the polarization element 1 according to Example 2 manufactured in the above-described manner, simulation is performed by changing the incident angle θ, and the transmittance (Tp) of the transmission axis, the reflectance (Rs) of the reflection axis, and Tp×Rs required for the polarization beam splitter (PBS) are respectively calculated. In addition, as the values of Tp and Rs, the average values of a plurality of Tp and Rs values calculated by changing the wavelength λ of the incident light in the range of 430 to 680 nm and for each wavelength of the incident light are used. The relationships between Tp, Rs, Tp×Rs and θ calculated in the above-described manner are shown in​ (b)–(d) curve graphs

[0508] As ​ shown in (a) of ​ , the grid of Example 2 (the structure formed by combining the rib portion 22 and the reflective film 30) has the above-mentioned special tree shape as in Example 1. Therefore, for obliquely incident light with a large and wide range of incident angles θ, the transmittance and polarization separation characteristics are excellent.

[0509] Therefore, as ​ shown, it can be seen that in Example 2, in a wide range where the incident angle θ is 0° to 45°, a high Tp value of 74% or more is ensured. In particular, when θ = 30° or 45°, a high Tp of 88% or more can be ensured, and a high Tp × Rs of 74% or more can be ensured, having excellent polarization separation characteristics (Tp × Rs characteristics). Thus, it can be seen that the polarization element 1 of Example 2 can exhibit significantly excellent transmittance and polarization separation characteristics for obliquely incident light with an incident angle θ of 30° to 45°.

[0510] As in Example 2 described above, it can be seen that even when the shape of the rib portion 22 of the grid structure 20 is different from that of Example 1, better transmittance and polarization separation characteristics than those of Comparative Examples 1 to 3 can be obtained. However, when the incident angle θ is 60°, the Tp and Tp × Rs characteristics of Example 1 are superior to those of Example 2.

[0511] (Example 3)

[0512] Next, Example 3 of the present invention will be described with reference to ​ . In Example 3, the relationship between the height H of the rib portion 22 and the polarization characteristics of the polarization element 1 was verified.

[0513] As ​ shown in (a) of ​ , a model of the polarization element 1 according to Example 3 was fabricated. The model of Example 3 is the same as the above-mentioned model of Example 1. The cross-sectional shape of the rib portion 22 is trapezoidal, and it is a tapered shape that becomes thinner toward the front end 22a of the rib portion 22. The grid of Example 3 (the structure formed by combining the rib portion 22 and the reflective film 30) has the above-mentioned special tree shape as in Example 1. In Example 3, the coverage rate Rc was maintained at 45% and the height H of the rib portion 22 was changed stepwise in the range of 100 to 220 nm.

[0514] The dimensions and shapes of each part of the model of the polarization element 1 according to Example 3 are as follows.

[0515] P: 144 nm

[0516] W T : 19 nm

[0517] W M : 32.5 nm

[0518] W B : 46 nm

[0519] W MAX : 55 nm

[0520] H: 100 - 220 nm

[0521] Hx: 45 - 99 nm

[0522] Dt: 35 nm (maximum value)

[0523] Ds: 22.5 nm (maximum value)

[0524] Rc: 45%

[0525] Rr: 55%

[0526] θ: +45°

[0527] λ: 430 - 680 nm

[0528] Then, for the model of the polarization element 1 related to Example 3 fabricated in the above-described manner, simulations were carried out by changing the height H of the rib portion 22, and Tp, Rs, and Tp×Rs were calculated respectively. The incident angle θ was +45°. In addition, as the values of Tp and Rs, the average values of a plurality of Tp and Rs values calculated by changing the wavelength λ of the incident light in the range of 430 - 680 nm and for the incident light of each wavelength λ were used. In addition, the contrast ratio CR of the transmitted light was also calculated by dividing Tp by Ts.

[0529] The relationships between Tp, Rs, Tp×Rs, CR and H calculated in the above-described manner are shown in ​ the graphs of (b) - (e).

[0530] As ​ shown, it can be seen that in order to make the various characteristics (Tp, Tp×Rs, CR) of the polarization element 1 for obliquely incident light at 45° good, the height H of the rib portion 22 is preferably 160 nm or more, more preferably 180 nm or more, and particularly preferably 220 nm or more.

[0531] Specifically, regarding Tp, as ​ shown in (b), as long as H is 160 nm or more, Tp becomes 80% or more, and a high transmittance can be obtained, so it is preferred. Moreover, as long as H is 180 nm or more, Tp of 85% or more can be obtained, so it is more preferred. In addition, as long as H is 220 nm or more, Tp of 87% or more can be obtained, so it is particularly preferred.

[0532] In addition, regarding the Tp×Rs characteristics, as ​ shown in (d) of [], as long as H is 160 nm or more, excellent Tp×Rs of 70% or more can be obtained, so it is preferable. Moreover, as long as H is 180 nm or more, Tp×Rs of 75% or more can be obtained, so it is more preferable. In addition, as long as H is 220 nm or more, Tp×Rs of 77% or more can be obtained, so it is particularly preferable.

[0533] In addition, regarding the contrast ratio CR, as ​ shown in (e) of [], as long as H is 100 nm or more, a CR of 40 or more can be obtained. As long as H is 160 nm or more, excellent CR of 150 or more can be obtained, so it is preferable. Moreover, as long as H is 180 nm or more, excellent CR of 250 or more can be obtained, so it is more preferable. In addition, as long as H is 220 nm or more, excellent CR of 500 or more can be obtained, so it is particularly preferable.

[0534] (Example 4)

[0535] Next, Example 4 of the present invention will be described with reference to ​ . In Example 4, the relationship between the thickness Dt of the reflection film 30 (the front-end thickness Dt of the reflection film 30) covering the front end 22a of the convex strip portion 22 and the polarization characteristics of the polarization element 1 was verified.

[0536] As ​ shown in (a) of [], a model of the polarization element 1 according to Example 4 was fabricated. The model of Example 4 is the same as the model of Example 1 described above. The cross-sectional shape of the convex strip portion 22 is trapezoidal, and it is a tapered shape that becomes thinner toward the front end 22a of the convex strip portion 22. The grating (the structure body of the convex strip portion 22 and the reflection film 30) of Example 4 has the above-described special tree shape, similarly to Example 1. In Example 4, the front-end thickness Dt of the reflection film 30 was changed stepwise in the range of 5 to 35 nm.

[0537] The dimensions and shapes of the respective parts of the model of the polarization element 1 according to Example 4 are as follows.

[0538] P: 144 nm

[0539] W T : 19 nm

[0540] W M : 32.5 nm

[0541] W B : 46 nm

[0542] WMAX : 55 nm

[0543] H: 220 nm

[0544] Hx: 99 nm

[0545] Dt: 5 - 35 nm (maximum)

[0546] Ds: 22.5 nm (maximum)

[0547] Rc: 45%

[0548] Rr: 55%

[0549] θ: +45°

[0550] λ: 430 - 680 nm

[0551] Then, for the model of the polarization element 1 related to Example 4 fabricated in the above-described manner, the front thickness Dt of the reflective film 30 was changed for simulation, and Tp, Rs, Tp×Rs, and CR were calculated respectively. The incident angle θ was +45°. The relationships between Tp, Rs, Tp×Rs, and CR calculated in the above-described manner and Dt are shown in ​ (b) - (e) in the graph.

[0552] As ​ shown, it can be seen that in order to make various characteristics (Tp, Tp×Rs, CR) of the polarization element 1 for obliquely incident light at 45° good, the front thickness Dt of the reflective film 30 is preferably 5 nm or more, and more preferably 15 nm or more.

[0553] Specifically, regarding Tp, as ​ (b) in shows, as long as Dt is 5 nm or more, Tp becomes 85% or more, and a high transmittance can be obtained, so it is preferred. In addition, regarding Rs, as ​ (c) in shows, as long as Dt is 5 nm or more, Rs becomes 85% or more, and a high reflectance can be obtained, so it is preferred.

[0554] In addition, regarding the Tp×Rs characteristic, as ​ (d) in shows, as long as Dt is 15 nm or more, an excellent Tp×Rs of 78% or more can be obtained, so it is more preferred.

[0555] In addition, regarding the contrast ratio CR, as ​ (e) in shows, as long as Dt is 5 nm or more, an excellent CR of 100 or more can be obtained, so it is preferred. Moreover, as long as Dt is 15 nm or more, an excellent CR of 250 or more can be obtained, so it is more preferred.

[0556] (Example 5)

[0557] Next, refer to ​ to describe Embodiment 5 of the present invention. In Embodiment 5, the relationship between the thickness Ds of the reflective film 30 covering the side surface 22b of the rib portion 22 (the side thickness Ds of the reflective film 30) and the polarization characteristics of the polarization element 1 was verified.

[0558] As ​ (a) of shows, a model of the polarization element 1 according to Embodiment 5 was fabricated. The model of Embodiment 5 is the same as the model of Embodiment 1 described above. The cross-sectional shape of the rib portion 22 is trapezoidal, and it is a tapered shape that becomes thinner toward the front end 22a of the rib portion 22. The grating (the structure formed by combining the rib portion 22 and the reflective film 30) in Embodiment 5 has the above-described special tree shape, similarly to Embodiment 1. In Embodiment 5, the side thickness Ds of the reflective film 30 was changed stepwise within the range of 5 to 35 nm.

[0559] The dimensions and shapes of the respective parts of the model of the polarization element 1 according to Embodiment 5 are as follows.

[0560] P: 144 nm

[0561] W T : 19 nm

[0562] W M : 32.5 nm

[0563] W B : 46 nm

[0564] W MAX : 20 to 80 nm

[0565] H: 220 nm

[0566] Hx: 99 nm

[0567] Dt: 35 nm (maximum value)

[0568] Ds: 5 to 35 nm (maximum value)

[0569] Rc: 45%

[0570] Rr: 55%

[0571] θ: +45°

[0572] λ: 430 to 680 nm

[0573] Then, for the model of the polarization element 1 involved in Example 5 fabricated in the above-described manner, the side thickness Ds of the reflective film 30 was changed for simulation, and Tp, Rs, Tp×Rs, and CR were calculated respectively. The incident angle θ was +45°. The relationships between Tp, Rs, Tp×Rs, and CR calculated in the above-described manner and Dt are shown in ​ the graphs of (b) to (e).

[0574] As ​ shown, it can be seen that in order to obtain good various characteristics (Tp, Tp×Rs, CR) of the polarization element 1 with respect to obliquely incident light at 45°, the side thickness Ds of the reflective film 30 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.

[0575] Specifically, regarding Tp, as shown in (b) of ​ , as long as Ds is 10 nm or more and 30 nm or less, Tp becomes 80% or more, and a high transmittance can be obtained, so it is preferred. Moreover, as long as Ds is 12.5 nm or more and 25 nm or less, Tp becomes 85% or more, and a higher transmittance can be obtained, so it is more preferred. Moreover, as long as Ds is 15 nm or more and 20 nm or less, Tp becomes 87% or more, and a higher transmittance can be obtained, so it is particularly preferred.

[0576] In addition, regarding Rs, as shown in (c) of ​ , as long as Ds is 10 nm or more, Rs becomes 80% or more, and a high reflectance can be obtained, so it is preferred. Moreover, as long as Ds is 12.5 nm or more, Rs becomes 85% or more, and a higher reflectance can be obtained, so it is more preferred. Moreover, as long as Ds is 15 nm or more, Rs becomes 87% or more, and a higher reflectance can be obtained, so it is particularly preferred.

[0577] In addition, regarding the Tp×Rs characteristic, as shown in (d) of ​ , as long as Ds is 12.5 nm or more and 30 nm or less, an excellent Tp×Rs of 70% or more can be obtained, so it is preferred. Moreover, as long as Ds is 15 nm or more and 25 nm or less, an excellent Tp×Rs of 76% or more can be obtained, so it is more preferred.

[0578] In addition, regarding the contrast ratio CR, as shown in (e) of ​ , as long as Ds is 10 nm or more, it is sufficient, but as long as Ds is 12.5 nm or more, an excellent CR of 50 or more can be obtained, so it is preferred. Moreover, as long as Ds is 15 nm or more, an excellent CR of 100 or more can be obtained, so it is more preferred.

[0579] (Example 6)

[0580] Next, with reference to ​ Example 6 of the present invention will be described. In Example 6, the relationship between the coverage rate Rc of the side surface 22b of the rib portion 22 covered with the reflective film 30 and the polarization characteristics of the polarization element 1 was verified.

[0581] As shown in ​ (a) of, a model of the polarization element 1 related to Example 6 was fabricated. The model of Example 6 is the same as the model of Example 1 described above. The cross-sectional shape of the rib portion 22 is trapezoidal, and it is a tapered shape that becomes thinner toward the front end 22a of the rib portion 22. The grating (the structure formed by combining the rib portion 22 and the reflective film 30) in Example 6 has the above-described special tree shape, similarly to Example 1. In Example 6, the height Hx of the range in which the side surface 22b of the rib portion 22 is covered with the reflective film 30 was changed, so that its coverage rate Rc was changed stepwise within the range of 20 to 90%.

[0582] The dimensions and shapes of the respective parts of the model of the polarization element 1 related to Example 6 are as follows.

[0583] P: 144 nm

[0584] W T : 19 nm

[0585] W M : 32.5 nm

[0586] W B : 46 nm

[0587] W MAX : 55 nm

[0588] H: 220 nm

[0589] Hx: 44 - 198 nm

[0590] Dt: 35 nm (maximum value)

[0591] Ds: 22.5 nm (maximum value)

[0592] Rc: 20 - 90%

[0593] Rr: 80 - 10%

[0594] θ: +45°

[0595] λ: 430 - 680 nm

[0596] Then, for the model of the polarization element 1 related to Example 6 fabricated in the above-described manner, simulations were performed by changing the coverage ratio Rc, and Tp, Rs, Tp×Rs, and CR were calculated respectively. The incident angle θ was +45°. The relationships between Tp, Rs, Tp×Rs, and CR calculated in the above-described manner and Dt are shown in ​ the graphs of (b) to (e).

[0597] As ​ shown, it can be seen that in order to obtain good various characteristics (Tp, Tp×Rs, CR) of the polarization element 1 for obliquely incident light at 45°, the coverage ratio Rc is preferably 25% or more and 80% or less, more preferably 30% or more and 70% or less, still more preferably 30% or more and 60% or less, and particularly preferably 40% or more and 50% or less.

[0598] Specifically, regarding Tp, as ​ shown in (b), as long as Rc is 25% or more and 80% or less, Tp becomes 75% or more, and a high transmittance can be obtained, so it is preferred. Moreover, as long as Rc is 30% or more and 70% or less, Tp becomes 80% or more, and a higher transmittance can be obtained, so it is more preferred. Moreover, as long as Rc is 40% or more and 50% or less, Tp becomes 85% or more, and a higher transmittance can be obtained, so it is particularly preferred.

[0599] In addition, regarding Rs, as ​ shown in (c), as long as Rc is 20% or more, Rs becomes 85% or more, and a high reflectance can be obtained, so it is preferred.

[0600] In addition, regarding the Tp×Rs characteristic, as ​ shown in (d), as long as Rc is 25% or more and 80% or less, Tp×Rs becomes 70% or more, and excellent Tp×Rs characteristics can be obtained, so it is preferred. Moreover, as long as Rc is 30% or more and 70% or less, Tp×Rs becomes 72% or more, and as long as Rc is 30% or more and 60% or less, Tp×Rs becomes 75% or more, and more excellent Tp×Rs characteristics can be obtained, so it is more preferred. Moreover, as long as Rc is 40% or more and 50% or less, Tp×Rs becomes 77% or more, and more excellent Tp×Rs characteristics can be obtained, so it is particularly preferred.

[0601] In addition, regarding the contrast ratio CR, as ​ shown in (e), as long as Rc is 20% or more, but as long as Rc is 30% or more, excellent CR of 100 or more can be obtained, so it is preferred. Moreover, as long as Rc is 40% or more, excellent CR of 200 or more can be obtained, so it is more preferred.

[0602] (Example 7)

[0603] Next, with reference to ​ Example 7 of the present invention will be described. In Example 7, the relationship between the thickness Ds (side thickness Ds of the reflective film 30) of the reflective film 30 covering the side surface 22b of the rib portion 22, the incident angle θ, and the polarization characteristics of the polarization element 1 was verified.

[0604] As ​ (a) of shows, a model of the polarization element 1 according to Example 7 was fabricated. The model of Example 7 is the same as the model of Example 1 described above. The cross-sectional shape of the rib portion 22 is trapezoidal, and it has a tapered shape that becomes thinner toward the front end 22a of the rib portion 22. The grating (the structure formed by combining the rib portion 22 and the reflective film 30) of Example 7 has the above-described special tree shape, similarly to Example 1. In Example 7, the side thickness Ds of the reflective film 30 was gradually changed within the range of 17.5 to 25 nm, and the incident angle θ was gradually changed within the range of 0 to 60°.

[0605] The dimensions and shapes of the respective parts of the model of the polarization element 1 according to Example 7 are as follows.

[0606] P: 144 nm

[0607] W T : 19 nm

[0608] W M : 32.5 nm

[0609] W B : 46 nm

[0610] W MAX : 45 nm, 55 nm, 60 nm

[0611] H: 220 nm

[0612] Hx: 99 nm

[0613] Dt: 35 nm (maximum value)

[0614] Ds: 17.5 nm, 22.5 nm, 25 nm (maximum value)

[0615] Rc: 45%

[0616] Rr: 55%

[0617] θ: 0 to +60°

[0618] λ: 430 to 680 nm

[0619] Then, for the model of the polarization element 1 related to Example 7 fabricated in the above-described manner, the side thickness Ds and the incident angle θ of the reflective film 30 were changed for simulation, and Tp, Rs, and Tp×Rs were calculated respectively. The incident angle θ was changed stepwise every 15° within the range of 0 to +60°. The relationships between Tp, Rs, Tp×Rs and Dt calculated in the above-described manner are shown in ​ the graphs of (b) to (d).

[0620] As ​ shown, it can be seen that even when the side thickness Ds of the reflective film 30 is changed stepwise within the range of 17.5 to 25 nm, the polarization element 1 has good polarization characteristics (Tp, Rs, Tp×Rs) with respect to the obliquely incident light at a wide incident angle θ of 0° to +60°. In particular, it can be seen that very excellent polarization characteristics are exhibited with respect to the obliquely incident light at an incident angle θ of +45°.

[0621] Specifically, regarding Tp, as shown in (b) of ​ , even when Ds varies within the range of 17.5 to 25 nm, as long as θ is within the range of +30° to +60°, Tp becomes 75% or more, and a high transmittance can be obtained, so it is preferred. Moreover, as long as θ is +45°, Tp becomes 85% or more, and the highest transmittance can be obtained, so it is more preferred.

[0622] In addition, regarding Rs, as shown in (c) of ​ , within the range of a wide incident angle θ of 0° to +60°, Rs becomes 85% or more, and a high reflectance can be obtained, so it is preferred.

[0623] In addition, regarding the Tp×Rs characteristic, as shown in (d) of ​ , even when Ds varies within the range of 17.5 to 25 nm, as long as θ is within the range of +30° to +60°, Tp×Rs becomes 70% or more, and excellent Tp×Rs characteristics can be obtained, so it is preferred. Moreover, as long as θ is +45°, Tp×Rs becomes 76% or more, and the most excellent Tp×Rs characteristics can be obtained, so it is more preferred. In addition, the balance of the Tp×Rs characteristics is good with respect to the obliquely incident light at an incident angle θ within the range of 45°±15°. Therefore, when the polarization element 1 related to Example 7 is used as a polarization beam splitter to project an image, from the perspective of the observer, the balance of the brightness of the displayed image is good, and the image state is also good.

[0624] (Example 8)

[0625] Next, referring to ​Embodiment 8 of the present invention will be described. In Embodiment 8, the relationship between the deviation ratio when the reflective film 30 covering the convex rib portion 22 is biased to one side and the polarization characteristics of the polarization element 1 was verified.

[0626] As ​ shown in (a) of [], a model of the polarization element 1 according to Embodiment 8 was fabricated. The model of Embodiment 8 is the same as the model of the above Embodiment 1 except that the reflective film 30 is biased to one side of the convex rib portion 22. The cross-sectional shape of the convex rib portion 22 is trapezoidal, and it is a shape with a thinner head that becomes thinner toward the front end 22a of the convex rib portion 22. The grid (the structure body of the convex rib portion 22 and the reflective film 30 together) of Embodiment 8 has the above-mentioned special tree shape as in Embodiment 1.

[0627] In Embodiment 8, regarding the left side surface 22b of the convex rib portion 22, the side thickness Ds (left side) of the reflective film 30 covering this side surface 22b was fixed at 22.5 nm, the height Hx (left side) of the coverage range was fixed at 99 nm, and the coverage rate Rc (left side) was fixed at 45%. On the other hand, the side thickness Ds (right side) of the reflective film 30 covering the right side surface 22b of the convex rib portion 22 was changed stepwise in the range of 0 to 22.5 nm. Correspondingly, regarding the right side surface 22b of the convex rib portion 22, the height Hx (right side) of the coverage range of this right side surface 22b was changed stepwise in the range of 0 to 99 nm, and the coverage rate Rc (right side) was changed stepwise in the range of 0 to 45%. As a result, the maximum grid width W MAX was changed stepwise in the range of 32.5 to 55 nm.

[0628] In addition, in Embodiment 8, as the incident angle θ, two directions were used: the incident angle in the + direction obliquely incident on the left side of the convex rib portion 22 (θ = 0° to +60°) and the incident angle in the - direction obliquely incident on the right side of the convex rib portion 22 (θ = 0° to -60°).

[0629] The dimensions and shapes of each part of the model of the polarization element 1 according to Embodiment 8 are as follows.

[0630] P: 144 nm

[0631] W T : 19 nm

[0632] W M : 32.5 nm

[0633] W B : 46 nm

[0634] W MAX: 32.5nm, 37.5nm, 47.5nm, 55nm

[0635] H: 220nm

[0636] Hx (left side): 99nm

[0637] Hx (right side): 0 - 99nm

[0638] Dt: 35nm (maximum value)

[0639] Ds (left side): 22.5nm (maximum value)

[0640] Ds (right side): 0nm, 5nm, 10nm, 22.5nm (maximum value)

[0641] Rc (left side): 45%

[0642] Rc (right side): 0%, 22%, 33%, 45%

[0643] Rr (left side): 55%

[0644] Rc (right side): 100%, 78%, 67%, 55%

[0645] θ (left side): 0 - +60°

[0646] θ (right side): 0 - -60°

[0647] λ: 430 - 680nm

[0648] Then, for the model of the polarization element 1 related to Example 8 fabricated in the above-described manner, simulations are performed by changing Ds (right side) and Rc (right side) related to the left side surface 22b of the reflection film 30, and Tp, Rs, Tp×Rs, and CR are calculated respectively. The incident angle θ is changed stepwise every 15° within the range of 0 - +60°. The relationships between Tp, Rs, Tp×Rs, CR calculated in the above manner and Dt are shown in ​ (b) - (e) in the graph.

[0649] As ​ shown, it can be seen that even when the reflection film 30 is biased to one side of the rib portion 22, that is, when the grating is asymmetric left and right, the polarization element 1 also has good polarization characteristics (Tp, Rs, Tp×Rs, CR).

[0650] Specifically, regarding Tp, as ​As shown in (b) thereof, even when oblique incident light is incident on the grid deflected by the reflection film 30 from either the + direction or the - direction, both Tp(+) and Tp(-) become 85% or more, and high transmittance can be obtained on both sides of the grid. In this case, the difference between Tp(+) and Tp(-) is 3% or less, and it is confirmed that no significant difference is generated between Tp(+) and Tp(-) due to the incident direction of the oblique incident light.

[0651] In addition, regarding Rs, as ​ shown in (c) thereof, even when oblique incident light is incident on the grid deflected by the reflection film 30 from either the + direction or the - direction, both Rs(+) and Rs(-) become 85% or more, and high reflectance can be obtained on both sides of the grid.

[0652] In addition, regarding the Tp×Rs characteristic, as ​ shown in (d) thereof, even when oblique incident light is incident on the grid deflected by the reflection film 30 from either the + direction or the - direction, Tp×Rs also becomes 75% or more, and excellent Tp×Rs characteristics can be obtained.

[0653] In addition, regarding the contrast ratio CR, as ​ (e) shown, even when oblique incident light is incident on the grid deflected by the reflection film 30 from either the + direction or the - direction, excellent CR can be obtained. Moreover, preferably, Ds (right side) is 5 nm or more and the coverage rate (left side) is 22% or more, whereby excellent CR of 100 or more can be obtained. In addition to this, more preferably, Ds (right side) is 10 nm or more and the coverage rate (left side) is 33% or more, whereby more excellent CR of 150 or more can be obtained.

[0654] (Verification results of the shape of the reflection film: Example 9, Comparative Example 4)

[0655] Next, with reference to ​ and ​ Example 9 of the present invention (the reflection film 30 is circular) and Comparative Example 4 (the reflection film 30 is angular) are compared, and the verification results of the relationship between the shape of the reflection film 30 covering the convex strip portion 22 and the polarization characteristics of the polarization element 1 are described.

[0656] As ​ and ​ shown, a model of the polarization element 1 according to Example 9 and a model of the polarization element 1 according to Comparative Example 4 were fabricated.

[0657] The model of the polarization element 1 according to Example 9 has the same special tree shape as the model of the above Example 1 (refer to ​etc.). The grating of the polarization element 1 according to Example 9 has a base portion 21, a rib portion 22 having a trapezoidal cross-sectional shape, and a reflective film 30 covering the top portion (the front end 22a and the upper side of the side surface 22b) of the rib portion 22. However, compared with the model of Example 1 described above, the coverage rate Rc of the two side surfaces 22b of the rib portion 22 covered by the reflective film 30 is different in the model of the polarization element 1 according to Example 9, and the coverage rate Rc of Example 9 is 45%. The reflective film 30 of Example 9 has a shape that roundly wraps the top portion of the rib portion 22. The surface of the reflective film 30 of Example 9 is substantially elliptical with a circular shape that bulges outward, and bulges in the width direction (X direction) of the rib portion 22. The surface of the reflective film 30 of Example 9 involved becomes a smoothly curved surface shape and does not have angular corner portions or stepped portions. Hereinafter, the reflective film 30 of Example 9 will be referred to as a circular reflective film.

[0658] On the other hand, compared with the model of Example 9, the shape of the reflective film 30 is different in the model of the polarization element 1 according to Comparative Example 4. The reflective film 30 of Comparative Example 4 has an angular shape and has two angular corner portions at the left and right ends of the top of the reflective film 30, which is different from the circularly bulging shape (circular reflective film) of the reflective film 30 of Example 9 described above. Hereinafter, the reflective film 30 of Comparative Example 4 will be referred to as an angular reflective film. In addition, the model of the polarization element 1 of this Comparative Example 4 corresponds to the wire grid polarizer disclosed in the above-mentioned Patent Document 7.

[0659] Thus, compared with Example 9, the shape of the reflective film 30 is different in Comparative Example 4, but other requirements are the same as those in Example 9.

[0660] The dimensions of the common parts in the models of the polarization element 1 of Example 9 and Comparative Example 4 are as follows.

[0661] P: 144 nm

[0662] W T : 19 nm

[0663] W M : 32.5 nm

[0664] W B : 46 nm

[0665] W MAX : 55 nm

[0666] H: 220 nm

[0667] Hx: 99 nm

[0668] Dt: 35 nm (maximum value)

[0669] Ds: 22.5 nm (maximum)

[0670] Rc: 45%

[0671] Rr: 55%

[0672] θ: 0° to +60°

[0673] λ: 430 to 680 nm

[0674] For the models of the polarization element 1 involved in Example 9 and Comparative Example 4 fabricated in the above-described manner, the incident angle θ was changed to perform simulations, and Tp, Rs, and Tp×Rs were calculated respectively. The incident angle θ was 0° to +60°.

[0675] The relationships between Tp, Rs, Tp×Rs calculated in the above manner and θ are shown in ​ the graphs of (b) to (d).

[0676] As ​ shown, in Example 9, in a wide range where the incident angle θ is 0° to 60°, a very high value of Tp of 78% or more is ensured. As a result, it can be seen that for obliquely incident light with respect to a large and wide range (30° to 60°) of the incident angle θ, a high Tp×Rs of 73% or more can be ensured, and it has excellent polarization separation characteristics (Tp×Rs characteristics). In particular, when θ = 45°, the value of Tp is very high at 87%, and the value of Tp×Rs is also very high at 78%. From this, it can be seen that the polarization element 1 of Example 9 can exhibit significantly excellent transmittance and polarization separation characteristics with respect to obliquely incident light at an incident angle θ of 45° and its vicinity.

[0677] Moreover, from ​ the comparison results between Example 9 and Comparative Example 4 shown, in Comparative Example 4, in the range where θ > 30°, as the incident angle θ increases, Tp and Tp×Rs decrease, and in particular, in the range where θ > 45°, Tp and Tp×Rs decrease rapidly.

[0678] In contrast, in Example 9, in the range of 0° ≤ θ ≤ 45°, as θ increases, Tp and Tp×Rs instead increase, and high values of Tp and Tp×Rs can be maintained. Moreover, in Example 9, in the range of 45° < θ ≤ 60°, even as θ increases, the degree of decrease in Tp and Tp×Rs is significantly suppressed compared to Comparative Example 4, and high values of Tp and Tp×Rs can be maintained. In particular, when θ = 45°, Example 9 can obtain Tp and Tp×Rs that are more than 5% higher than those in Comparative Example 4. In addition, when θ = 60°, Example 9 can obtain Tp and Tp×Rs that are more than 7% higher than those in Comparative Example 4. Thus, in Example 9, in a large and wide range of incident angles θ (30° to 60°, especially 45° to 60°), significantly excellent transmittance (transmittance Tp) and Tp×Rs characteristics can be obtained.

[0679] In addition, regarding Rs, compared with Comparative Example 4, Example 9 can obtain a high reflectivity with no significant difference.

[0680] In addition, regarding the Tp×Rs characteristics required for a polarization beam splitter (PBS), Example 9 is superior to Comparative Example 4, and the highest Tp×Rs characteristics can be obtained when the incident angle θ = 45°. In addition, even in the range of the incident angle θ = 30° to 60°, Example 9 can obtain better characteristics than Comparative Example 4. For obliquely incident light with a large and wide range of incident angles θ, the Tp×Rs characteristics are superior to those of Comparative Example 4. Moreover, in Example 9, for obliquely incident light with an incident angle θ in the range of 45° ± 15°, the balance of the Tp×Rs characteristics is good. Therefore, when the polarization element 1 according to Example 9 is used as a polarization beam splitter to project an image, from the perspective of an observer, the balance of the brightness of the displayed image is good, and the image state is also good.

[0681] Thus, it can be seen that when the polarization element 1 is used as a polarization beam splitter, compared with Comparative Example 4, for obliquely incident light with a large and wide range of incident angles θ from 30° to 60°, especially for obliquely incident light with an incident angle of 45°, the transmittance (transmittance Tp) of P-polarized light and the polarization separation characteristics (Tp×Rs characteristics) are significantly excellent. Therefore, it can be said that the polarization separation characteristics required for a polarization beam splitter can be fully satisfied with respect to obliquely incident light.

[0682] As described above, Example 9 having a circular reflection film 30 has a lower dependence on the incident angle θ of obliquely incident light compared with Comparative Example 4 having an angular reflection film 30, and the transmittance of obliquely incident light and the polarization separation characteristics (Tp×Rs characteristics) as a polarization beam splitter are excellent. The reason for this will be described below with reference to ​ for illustration.

[0683] As ​ shown, the transmittance of incident light in the wire grid polarizing element 1 is basically determined by the ratio of the effective grid width W A to the gap width W G (W G / W A ). The grid width W A is the width of one reflective film 30 in the direction perpendicular to the traveling direction of the incident light, and the gap width W G is the width of the gap between two adjacent reflective films 30 in the direction perpendicular to the traveling direction of the incident light. The smaller the width of the reflective film 30 (the width of the metal grid portion) occupied by one pitch of the grid structure 20, the less incident light is reflected by the reflective film 30 with such a small width, so the transmittance of the incident light increases.

[0684] Here, as ​ shown, consider the case where incident light is obliquely incident on the polarizing element 1 (i.e., the case where θ > 0°). In this case, in Example 9 where the reflective film 30 is circular, compared with the conventional Example 4 where the reflective film 30 is angular, the effective grid width W A seen obliquely decreases, and the gap width W G seen obliquely increases. Therefore, when obliquely incident light is incident on the polarizing element 1, the transmittance Tp of Example 9 is higher than the transmittance Tp of the conventional Example 4. As a result, the Tp×Rs characteristic of Example 9 is superior to that of the conventional Example 4. For example, it can be seen that when the incident angle θ of the obliquely incident light is 45°, the transmittance Tp and Tp×Rs of Example 9 are respectively about 5% higher than those of the conventional Example 4, and when θ is 60°, the transmittance Tp and Tp×Rs of Example 9 are respectively about 7% higher than those of the conventional Example 4 (refer to ​ (b)(d)).

[0685] For the above reasons, it can be said that Example 9 having a circular reflective film 30 has a lower dependence on the incident angle θ of obliquely incident light compared with the conventional Example 4 having an angular reflective film 30, and has excellent transmittance of obliquely incident light and polarization separation characteristics (Tp×Rs characteristics) as a polarization beam splitter.

[0686] <2. Verification results of heat dissipation>

[0687] Next, a comparison is made between the hybrid wire grid polarizing element 1 composed of an inorganic material and an organic material according to an embodiment of the present invention and the film type wire grid polarizing element composed of an organic material according to the conventional example, and the results of verifying the heat dissipation of the polarizing element 1 are described.

[0688] As described above, in the wire grid polarizing element 1 according to the above-described embodiment of the present invention, the substrate 10 is made of an inorganic material such as glass having extremely excellent heat resistance. Further, the base portion 21 and the plurality of rib portions 22 of the grid structure 20 directly provided on the substrate 10 are integrally formed of an organic material having heat resistance. Thus, the wire grid polarizing element 1 according to the present embodiment is a hybrid polarizing element in which an organic material and an inorganic material are combined. Therefore, the overall thermal resistance R [m 2 ·K / W] of the polarizing element 1 is small, and heat can be effectively released from the grid structure 20 to the substrate 10, so it is considered that the heat dissipation performance is excellent.

[0689] On the other hand, since the film-type wire grid polarizing element of the conventional example is mainly made of an organic material, the heat resistance (about 100°C) is low. In addition, since the total thickness of the organic material layer composed of the substrate (base film), the double-sided adhesive (OCA), and the grid structure increases, it is considered that the thermal resistance R of the organic material layer also increases.

[0690] Therefore, the hybrid wire grid polarizing element 1 according to the present embodiment is excellent in heat resistance and heat dissipation performance as compared with the conventional film-type polarizing element made of an organic material (heat resistance: about 100°C), and has heat resistance in a high-temperature environment of up to about 200°C, for example. From this, it is considered that the hybrid wire grid polarizing element 1 according to the present embodiment can achieve excellent polarization characteristics and can exhibit good heat dissipation characteristics.

[0691] Here, an example of the hybrid wire grid polarizing element of the present invention and a film-type wire grid polarizing element of the conventional example were actually manufactured, and the thermal resistance R and heat dissipation performance thereof were verified.

[0692] Table 1 shows the types and thermal conductivities λ [W / m·K] of general base materials. In Table 2, for the hybrid wire grid polarizing element 1 according to the example of the present invention and the film-type wire grid polarizing element according to the conventional example, the thicknesses of the respective layers made of an organic material (PMMA), the thickness of the entire multilayer made of an organic material (PMMA) (total thickness D ALL ), and the thermal resistance R [m 2 ·K / W] are shown.

[0693]

Table 1

[0694] [Table 1]

[0695]

[0696]

Table 2

[0697] [Table 2]

[0698]

[0699]

[0700] As shown in Table 2, in the hybrid polarization element 1 according to the embodiment, the base portion 21 and the rib portion 22 constituting the grid structure 20 are formed of an organic material, and the substrate 10 is formed of an inorganic material. On the other hand, in the film-type polarization element according to the prior example, the substrate, the base portion constituting the grid structure, and the double-sided tape for bonding the base portion to the substrate are all formed of an organic material. Here, as the organic material, PMMA (Poly Methyl Methacrylate) is used. As a result, the total thickness D of the PMMA material of the hybrid polarization element 1 according to the embodiment ALL becomes 0.0302 [mm]. On the other hand, the total thickness D of the PMMA material of the film-type polarization element according to the prior example ALL becomes 0.2552 [mm], which is much larger than D of the embodiment ALL .

[0701] As shown in Table 1, the thermal conductivity λ of PMMA is 0.21 [W / m·K]. The thermal resistance R [m 2 ·K / W] is obtained by dividing "the thickness D of the material ALL [mm]" by "the thermal conductivity λ [W / m·K]" (R = (D ALL / 1000) / λ). Thus, the thermal resistance R of the grid structure 20 of the hybrid polarization element 1 according to the embodiment becomes 0.000144 [m 2 ·K / W]. On the other hand, the thermal resistance R of the film-type polarization element according to the prior example becomes 0.001215 [m 2 ·K / W].

[0702] Therefore, by using the hybrid polarization element 1 according to the embodiment of the present invention, the value of the thermal resistance R of the grid structure 20 made of the PMMA material can be reduced to about 1 / 8.4 compared with the film-type polarization element according to the prior example. Thus, according to the hybrid polarization element 1 according to the embodiment of the present invention, the heat of the grid structure 20 made of an organic material (such as PMMA) can be effectively released to the outside through the substrate 10 made of an inorganic material, which has excellent heat resistance and heat dissipation compared with the organic material, for heat dissipation. Therefore, the hybrid polarization element 1 according to the embodiment of the present invention has very excellent heat resistance and heat dissipation compared with the prior example.

[0703] In addition, the relationship between the thickness TB of the base portion 21 of the grid structure 20 directly provided on the substrate 10 and the temperature difference ΔT between the front and back surfaces of the base portion 21 was verified when the polarization element 1 was mounted on a projection display device such as a projector and light of about 5000 [lm (lumen)] was irradiated onto the polarization element 1. The verification results will be described below. In addition, the temperature difference ΔT is the temperature difference (ΔT = T1 - T2) between the temperature T1 of the outermost surface (the root portions of the plurality of rib portions 22) of the base portion 21 and the temperature T2 of the base portion 21 at the interface between the base portion 21 and the substrate 10.

[0704] ​ It is a graph showing the relationship between the wavelength of light in the bright and dark places and the relative luminous efficiency. The luminous efficiency K (spectral luminous efficacy) is represented by a numerical value indicating the intensity of the brightness of each wavelength of light perceived by the human eye. That is, the luminous efficiency K represents the luminous flux [lm] perceived per 1 W of light (electromagnetic wave) emission flux. The unit of the emission flux is [W], the unit of the luminous flux (photometric quantity) is [lm], and the unit of the luminous efficiency K is [lm / W]. The luminous efficiency K varies according to the wavelength of light (electromagnetic wave), and the luminous efficiency becomes the highest when the wavelength of light is 555 nm. The maximum luminous efficiency K at this time is 683 [lm / W], and this 683 [lm / W] is called the maximum luminous efficiency K. m . In addition, the relative luminous efficiency V is represented by the ratio of the luminous efficiency K of a certain wavelength to the maximum luminous efficiency K m (= 683 [lm / W]) (V = K / K m ). The relative luminous efficiency V is a value from 0 to 1.0 and has no unit for the relative luminous efficiency V.

[0705] As ​ shown, the brightness (luminous efficiency K, relative luminous efficiency V) perceived by the human eye varies greatly according to the wavelength of light. In the bright place, the human eye perceives light near the wavelength of 555 nm most strongly, and in the dark place, it perceives light near the wavelength of 507 nm most strongly. Since a projector can be used in various occasions such as bright places and dim places, the light of the projector that the human eye brightly perceives is light near the wavelength of 528 nm regardless of whether it is in a bright or dark place. Therefore, the result of calculating the output power Pw [W] of the light source of the projector when irradiating light near the wavelength of 528 nm with a brightness (luminous flux) of 5000 [lm] from the projector is shown in Table 3.

[0706]

Table 3

[0707] [Table 3]

[0708] ​ ​ ​ 555 1 683 528 0.84 573.7

[0709] ​ ​ ​ 528 5000 8.7

[0710] As described above, in the light, the human eye feels the light near the wavelength of 555 nm most strongly. That is to say, ​ in the curve of the standard relative luminosity in the light shown in the graph, the wavelength at which the maximum luminosity K m is reached is near 555 nm. The luminosity K at the wavelength of 555 nm is the maximum luminosity K m = 683 [lm / W]. According to ​ the graph, at the wavelength of 528 nm, the relative luminosity V is 0.84. When the maximum luminosity K m at the wavelength of 555 nm is 683 [lm / W], the luminosity K at the wavelength of 528 nm is 573.7 [lm / W] (683 [lm / W] × 0.84 ≈ 573.7 [lm / W]). Therefore, when 5000 [lm] of light is irradiated from a projector, the output power Pw (the electromagnetic beam irradiated from the light source) of the light source of the projector becomes 8.7 [W] (5000 [lm] / 573.7 [lm / W] ≈ 8.7 [W]).

[0711] Consider the case where the output power Pw of the light source of the projector is set to this 8.7 [W], and the light with a wavelength of 528 nm is irradiated onto a rectangular plate-shaped polarization element 1 with a length in the vertical (Y direction): 10 [mm] × width in the horizontal (X direction): 20 [mm]. In this case, when the surface area of the polarization element 1 is A [m 2 , the output power Pw' per unit area of the surface of the polarization element 1 becomes Pw' [W / m 2 = Pw [W] / A [m 2 . In this case, the temperature difference ΔT between the temperature T1 of the outermost surface of the base 21 and the temperature T2 at the interface between the base 21 and the substrate 10 was evaluated according to how the thickness TB of the base 21 changes. At this time, the thickness TB of the base 21 was changed in the range of 0.010 to 0.255 [mm]. The relationship between the thickness TB of the base 21 and the temperature difference ΔT is shown in Table 4. In addition, as the material of the grid structure 20 of the polarization element 1, PMMA is used. The thermal conductivity λ of PMMA is 0.21 [W / m·K]. In addition, the calculation formula for the temperature difference ΔT is as follows.

[0712] Temperature difference ΔT [K] = Thermal resistance R [m 2 ·K / W] × Output power Pw' per unit area [W / m 2

[0713] Here, since the temperature difference ΔT is a relative temperature, the temperature difference ΔT [K] = the temperature difference ΔT [°C]. Thus, regarding the unit of ΔT, 1 [K] = 1 [°C].​

[0714]

Table 4

[0715] [Table 4]

[0716]

[0717] As shown in Table 4, in Examples 1 to 10 of the present invention, the hybrid wire grid polarizing element 1 composed of an inorganic material (substrate 10) and an organic material (grid structure 20) is used. On the other hand, in the prior art example, a film-type wire grid polarizing element composed of an organic material is used.

[0718] In addition, the thickness TB (= 0.255 mm) of the base portion of the prior art example shown in Table 4 means "the total thickness D as the PMMA material" in the film-type wire grid polarizing element. ALL (see Table 2)". Considering the thicknesses of generally circulated films and double-sided adhesives (OCA), the prior art example shows a structural example of the thinnest film-type wire grid polarizing element. Therefore, in a film-type wire grid polarizing element formed by laminating multiple films and double-sided adhesives, it is considered that it is more difficult to make the total thickness D ALL thinner than the prior art example shown in Table 4. In contrast, the hybrid wire grid polarizing element 1 of Examples 1 to 10 has a structure in which the grid structure 20 composed of an organic material (PMMA) is directly formed on the substrate 10 composed of an inorganic material. Therefore, in Examples 1 to 10, as shown in Table 4, the thickness TB of the base portion 21 (≈ the total thickness D as the PMMA material) ALL can be much thinner than the prior art example.

[0719] As can be seen from Table 4, in the film-type wire grid polarizing element of the prior art example, the thickness TB of the base portion (= the total thickness D as the PMMA material) ALL is as thick as 0.255 [mm], so the temperature difference ΔT between the front and back of the base portion becomes 52.9 °C, and as a result, it exceeds 50 °C. In addition, since the internal space of the projector is airtight, the ambient temperature of the wire grid polarizing element and the like installed inside the projector becomes 50 °C or higher. Moreover, when the projector is a high-brightness model, sometimes the ambient temperature of the wire grid polarizing element and the like approaches 100 °C. Therefore, in the case of the film-type wire grid polarizing element of the prior art example, the surface temperature of the grid structure may also locally exceed 150 °C, which is a problem in terms of the durability of the wire grid polarizing element.

[0720] In contrast, the hybrid wire grid polarizing element 1 according to Examples 1 to 10 of the present invention has a structure in which the base portion 21 and the plurality of rib portions 22 of the grid structure 20 are directly formed on the substrate 10 composed of an inorganic material. From this, it can be seen that since Examples 1 to 10 can significantly reduce the thickness TB of the base portion 21 (≈ the total thickness D as the PMMA material) compared with the prior art example ALL), so that the temperature difference ΔT can be significantly reduced. As a result, in Examples 1 to 10, the heat of the base portion 21 of the grating structure 20 can be dissipated to the outside through the substrate 10 made of an inorganic material, so it is confirmed that the heat dissipation and durability of the polarization element 1 are excellent.

[0721] Here, in Examples 1 to 10, it is known that by making the thickness TB of the base portion 21 0.15 [mm] or less, the temperature difference ΔT can be suppressed to 32 °C or less. Compared with the temperature difference ΔT = 52.9 °C of the existing example, the temperature difference ΔT can be reduced by about 40% or more. From this, it is confirmed that by making the thickness TB of the base portion 21 0.15 [mm] or less, the heat of the grating structure 20 can be quickly transferred to the substrate 10 and then effectively released from the substrate 10 to the outside for heat dissipation.

[0722] Moreover, in Examples 3 to 10, it is known that by making the thickness TB of the base portion 21 0.09 [mm] or less, the temperature difference ΔT can be suppressed to 20 °C or less. Compared with the temperature difference ΔT = 52.9 °C of the existing example, the temperature difference ΔT can be reduced by about 65% or more. Thus, by making the thickness TB of the base portion 21 0.09 [mm] or less, the heat of the grating structure 20 can be transferred to the substrate 10 more quickly and then more effectively released from the substrate 10 to the outside for heat dissipation. From this, it is confirmed that the reliability of the heat dissipation of the wire grid polarizing element 1 can be further improved.

[0723] In particular, by making the thickness TB of the base portion 21 0.045 [mm] or less, the temperature difference ΔT can be suppressed to 10 °C or less. Compared with the temperature difference ΔT = 52.9 °C of the existing example, the temperature difference ΔT can be reduced by about 80% or more. From this, from the viewpoint of improving the reliability of heat dissipation, it is known that the thickness TB of the base portion 21 is more preferably 0.045 [mm] or less. In addition, by making the thickness TB of the base portion 21 0.02 [mm] or less, the temperature difference ΔT can be suppressed to 5 °C or less. Compared with the temperature difference ΔT = 52.9 °C of the existing example, the temperature difference ΔT can be reduced by about 90% or more. From this, from the viewpoint of improving the reliability of heat dissipation, it is known that the thickness TB of the base portion 21 is further preferably 0.002 [mm] or less.

[0724] Thus, it is confirmed that in order to improve the heat dissipation and durability of the polarization element 1, the thickness TB of the base portion 21 is preferably 0.09 [mm] or less, more preferably 0.045 [mm] or less, and particularly preferably 0.02 [mm] or less.

[0725] In addition, in the above examples, PMMA is used as the material of the grating structure 20, but it is not limited to the examples involved. As the material of the grating structure of the present invention, various organic materials other than PMMA can also be used.

[0726] <3. Verification Results of the Composition of the Organic Material (UV-Curable Acrylic Resin for Imprinting)>

[0727] As the UV-curable acrylic resin for imprinting, Examples 31 to 38 and Comparative Examples 1 to 9 were prepared.

[0728] The viscosities of the UV-curable acrylic resins for imprinting according to Examples 31 to 38 and Comparative Examples 1 to 9 were measured. The viscosity was measured using a cone plate in a Brookfield viscometer manufactured by Eiko Seiki Co., Ltd.

[0729] The YI value of the cured products of the UV-curable acrylic resins for imprinting according to Examples 31 to 38 and Comparative Examples 1 to 9 after being held at 120°C for 500 hours (heat treatment) was measured. The YI value was calculated based on the measurement results using a UV-visible near-infrared spectrophotometer V-770 manufactured by JASCO Corporation. The measurement conditions and the calculation method of the YI value when calculating the YI value were the same as those in the above-described embodiment.

[0730] For the cured products of the UV-curable acrylic resins for imprinting according to Examples 31 to 38 and Comparative Examples 1 to 9, 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 before the heat treatment (held at 120°C for 500 hours) were measured. In addition, after the cured products of the UV-curable acrylic resins for imprinting according to Examples 31 to 38 and Comparative Examples 1 to 9 were held 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 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 performing a simple average on the obtained 251 measurement data. The average transmittance was measured using a UV-visible near-infrared spectrophotometer V-770 manufactured by JASCO Corporation.

[0731] Measure the storage moduli of the cured products of the UV-curable acrylic resins for imprinting involved in Examples 31 to 38 and Comparative Examples 1 to 9 at 30°C, 120°C, 130°C, and 140°C. The storage moduli were measured using a DMA7100 manufactured by Hitachi High-Technologies Corporation. Cut the sheets of the cured products of the UV-curable acrylic resins for imprinting involved in Examples 31 to 38 and Comparative Examples 1 to 9 into a length of 20 mm × a width of 3 mm. In the tensile mode, at a certain frequency (1 Hz), increase the temperature at a rate of 5°C per minute, and measure the storage moduli at 25°C to 300°C.

[0732] Measure the glass transition temperature Tg of the cured products of the UV-curable acrylic resins for imprinting involved in Examples 31 to 38 and Comparative Examples 1 to 9. The glass transition temperature Tg was measured using a DMA7100 manufactured by Hitachi High-Technologies Corporation. By cutting the sheets of the cured products of the UV-curable acrylic resins for imprinting involved in Examples 31 to 38 and Comparative Examples 1 to 9 into a length of 20 mm × a width of 3 mm, in the tensile mode, at a certain frequency (1 Hz), increase the temperature at a rate of 5°C per minute, and determine the maximum value of the loss tangent tanδ at 25°C to 300°C for measurement.

[0733] The compositions and viscosities of the UV-curable acrylic resins for imprinting in Examples 31 to 34 are shown in Table 5 below. The YI values, average transmittances, storage moduli, and glass transition temperatures Tg of the cured products of the UV-curable acrylic resins for imprinting involved in Examples 31 to 34 are shown in Table 6 below.

[0734] The compositions and viscosities of the UV-curable acrylic resins for imprinting in Examples 35 to 38 are shown in Table 7 below. The YI values, average transmittances, storage moduli, and glass transition temperatures Tg of the cured products of the UV-curable acrylic resins for imprinting involved in Examples 35 to 38 are shown in Table 8 below.

[0735] The compositions and viscosities of the UV-curable acrylic resins for imprinting in Comparative Examples 1 to 3 are shown in Table 9 below. The YI values, average transmittances, storage moduli, and glass transition temperatures Tg of the cured products of the UV-curable acrylic resins for imprinting involved in Comparative Examples 1 to 3 are shown in Table 10 below.

[0736] The compositions and viscosities of the UV-curable acrylic resins for imprinting in Comparative Examples 4 to 6 are shown in Table 11 below. The YI values, average transmittances, storage moduli, and glass transition temperatures Tg of the cured products of the UV-curable acrylic resins for imprinting involved in Comparative Examples 4 to 6 are shown in Table 12 below.

[0737] The compositions and viscosities of the UV-curable acrylic resins for imprinting in Comparative Examples 7 to 9 are shown in Table 13 below. The YI values, average transmittances, storage moduli, and glass transition temperatures Tg of the cured products of the UV-curable acrylic resins for imprinting in Comparative Examples 7 to 9 are shown in Table 14 below.

[0738] In addition, the unit of the content ratio in Tables 5, 7, 9, 11, and 13 is mass%. In addition, the viscosity in Tables 5, 7, 9, 11, and 13 is the viscosity [mPa·s] at 25°C.

[0739]

Table 5

[0740] [Table 5]

[0741]

[0742]

Table 6

[0743] [Table 6]

[0744]

[0745] [Example 31]

[0746] As shown in Table 5, in Example 31, as the photopolymerizable components, only Resin (A), Resin (B), Resin (C), and Resin (D) were contained, and a photopolymerization initiator was also contained. As Resin (A), “KAYARAD R-684” manufactured by Nippon Kayaku Co., Ltd. was used. As Resin (B), 1,6-hexanediol diacrylate (HDDA) was used. As Resin (C), isobornyl acrylate (IBOA) was used. As the isobornyl acrylate, “IBOA-B” manufactured by DAICEL-ALLNEX Co., Ltd. was used. As Resin (D), dipentaerythritol hexaacrylate (DPHA) was used. As the photopolymerization initiator, “Irgacure819” manufactured by IGM Resins B.V. was used. In addition, in Example 31, the content ratio of Resin (A) in the total photopolymerizable components was 30 mass%, the content ratio of Resin (B) was 20 mass%, the content ratio of Resin (C) was 30 mass%, and the content ratio of Resin (D) was 20 mass%. That is, in Example 31, the total content ratio of Resin (A) and Resin (B) in the total photopolymerizable components was 50 mass%, and the total content ratio of Resin (B) and Resin (C) was 50%. In addition, in Example 31, when the content ratio of the total photopolymerizable components was 100 mass%, the content ratio of the photopolymerization initiator was 1 mass%.

[0747] As shown in Table 5, the viscosity of the UV-curable acrylic resin for imprinting in Example 31 was 34.4 mPa·s.

[0748] As shown in Table 6, the YI value of the cured product of the UV-curable acrylic resin for imprinting in Example 31 was 2.4. From the above results, it was confirmed that even when the cured product of Example 31 was heat-treated, a low YI value could be maintained.

[0749] As shown in Table 6, the average transmittance of the cured product of the UV-curable acrylic resin for imprinting in Example 31 with respect to light in the wavelength range of 430 nm or more and 680 nm or less before heat treatment was 92.2%, and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less before heat treatment was 91.9%. In addition, the average transmittance of the cured product of the UV-curable acrylic resin for imprinting in Example 31 with respect to light in the wavelength range of 430 nm or more and 680 nm or less after heat treatment was 91.7%, and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less after heat treatment was 90.7%.

[0750] In the cured product of Example 31, the difference ΔA 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 (average transmittance before heat treatment - average transmittance after heat treatment) was -0.5%. In the cured product of Example 31, 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 -1.2%. From the above results, it was confirmed that even when the cured product of Example 31 was heat-treated, 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.

[0751] As shown in Table 6, the storage modulus of the cured product of the UV-curable acrylic resin for imprinting in Example 31 at 30 °C was 1.6×10 9 Pa. The storage modulus of the cured product of the UV-curable acrylic resin for imprinting in Example 31 at 120 °C was 6.5×10 8 Pa. The storage modulus of the cured product of the UV-curable acrylic resin for imprinting in Example 31 at 130 °C was 5.7×10 8 Pa. The storage modulus of the cured product of the UV-curable acrylic resin for imprinting in Example 31 at 140 °C was 5.0×10 8 Pa.

[0752] The rate of change of the storage modulus at 120°C relative to the storage modulus at 30°C (storage modulus at 120°C / storage modulus at 30°C × 100%) of the cured product of Example 31 was 41.6%. The rate of change of the storage modulus at 130°C relative to the storage modulus at 30°C (storage modulus at 130°C / storage modulus at 30°C × 100%) of the cured product of Example 31 was 36.4%. The rate of change of the storage modulus at 140°C relative to the storage modulus at 30°C (storage modulus at 140°C / storage modulus at 30°C × 100%) of the cured product of Example 31 was 31.8%. From the above results, it was confirmed that the cured product of Example 31 had a high storage modulus of 1.6×10 9 Pa before the heat treatment was carried out. In addition, it was also confirmed that even when the heat treatment was carried out on the cured product of Example 31, the decrease in the storage modulus was suppressed.

[0753] As shown in Table 6, the glass transition temperature Tg of the cured product of the imprinting photocurable acrylic resin of Example 31 was 142.6°C. From the above results, it was confirmed that the cured product of Example 31 had a high glass transition temperature Tg.

[0754] [Example 32]

[0755] As shown in Table 5, in Example 32, as the photopolymerizable components, only resin (A), resin (B), resin (C), and resin (D) were contained, and a photopolymerization initiator was also contained. Resin (A), resin (B), resin (C), resin (D), and the photopolymerization initiator were the same as those in Example 31. In Example 32, the content ratio of resin (A) in the whole photopolymerizable components was 40% by mass, the content ratio of resin (B) was 30% by mass, the content ratio of resin (C) was 29% by mass, and the content ratio of resin (D) was 1% by mass. That is, in Example 32, the total content ratio of resin (A) and resin (B) in the whole photopolymerizable components was 70% by mass, and the total content ratio of resin (B) and resin (C) was 59%. In addition, in Example 32, when the content ratio of the whole photopolymerizable components was 100% by mass, the content ratio of the photopolymerization initiator was 1% by mass. That is, only the content ratios of resins (A) to (D) in Example 32 were different from those in Example 31.

[0756] As shown in Table 5, the viscosity of the UV-curable acrylic resin for imprinting in Example 32 was 17.4 mPa·s. When the UV-curable acrylic resin for imprinting in Example 32 was compared with the UV-curable acrylic resin for imprinting in Example 31, the total content ratio of Resin (B) and Resin (C) was high, and the content ratio of Resin (D) was low. Therefore, it was speculated that the viscosity of the UV-curable acrylic resin for imprinting in Example 32 was lower than that of the UV-curable acrylic resin for imprinting in Example 31.

[0757] As shown in Table 6, the YI value of the cured product of the UV-curable acrylic resin for imprinting in Example 32 was 1.9. Based on the above results, it was confirmed that even when the cured product of Example 32 was heat-treated, a low YI value could be maintained. When the UV-curable acrylic resin for imprinting in Example 32 was compared with the UV-curable acrylic resin for imprinting in Example 31, the total content ratio of Resin (A) and Resin (B) was high. Therefore, it was speculated that the YI value of the cured product of the UV-curable acrylic resin for imprinting in Example 32 was lower than that of the cured product of the UV-curable acrylic resin for imprinting in Example 31.

[0758] As shown in Table 6, the average transmittance of the cured product of the UV-curable acrylic resin for imprinting in Example 32 for light in the wavelength range of 430 nm or more and 680 nm or less before heat treatment was 91.5%, and the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less before heat treatment was 91.1%. In addition, the average transmittance of the cured product of the UV-curable acrylic resin for imprinting in Example 32 for light in the wavelength range of 430 nm or more and 680 nm or less after heat treatment was 91.4%, and the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less after heat treatment was 90.5%.

[0759] In the cured product of Example 32, the difference ΔA in the average transmittance of light in the wavelength range of 430 nm or more and 680 nm or less before and after the heat treatment (average transmittance before the heat treatment - average transmittance after the heat treatment) became -0.1%. In the cured product of Example 32, 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 the heat treatment became -0.6%. Based on the above results, it was confirmed that even when the cured product of Example 32 was subjected to heat treatment, 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. Compared with the imprinting photocurable acrylic resin of Example 31, the total content ratio of resin (A) and resin (B) in the imprinting photocurable acrylic resin of Example 32 was high. Therefore, it was speculated that the difference ΔA in the average transmittance of the cured product of the imprinting photocurable acrylic resin of Example 32 was smaller than the difference ΔA in the average transmittance of the cured product of the imprinting photocurable acrylic resin of Example 31.

[0760] As shown in Table 6, the storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 32 at 30 °C was 2.0×10 9 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 32 at 120 °C was 6.2×10 8 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 32 at 130 °C was 5.6×10 8 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 32 at 140 °C was 5.0×10 8 Pa.

[0761] The change rate of the storage modulus at 120 °C with respect to the storage modulus at 30 °C (storage modulus at 120 °C / storage modulus at 30 °C × 100%) of the cured product of Example 32 became 30.9%. The change rate of the storage modulus at 130 °C with respect to the storage modulus at 30 °C (storage modulus at 130 °C / storage modulus at 30 °C × 100%) of the cured product of Example 32 became 27.6%. The change rate of the storage modulus at 140 °C with respect to the storage modulus at 30 °C (storage modulus at 140 °C / storage modulus at 30 °C × 100%) of the cured product of Example 32 became 25.0%. Based on the above results, it was confirmed that the cured product of Example 32 had a high storage modulus of 2.0×10 9 Pa before the heat treatment. In addition, it was also confirmed that even when the cured product of Example 32 was subjected to heat treatment, the decrease in the storage modulus was suppressed.

[0762] As shown in Table 6, the glass transition temperature Tg of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 32 was 174.2 °C. From the above results, it was confirmed that the cured product of Example 32 had a high glass transition temperature Tg.

[0763] [Example 33]

[0764] As shown in Table 5, in Example 33, as the photopolymerizable components, only Resin (A), Resin (B), Resin (C), and Resin (D) were included, and a photoinitiator was also included. Resin (A), Resin (B), Resin (C), Resin (D), and the photoinitiator were the same as those in Example 31. In Example 33, the content ratio of Resin (A) in the whole photopolymerizable components was 20% by mass, the content ratio of Resin (B) was 40% by mass, the content ratio of Resin (C) was 30% by mass, and the content ratio of Resin (D) was 10% by mass. That is, in Example 33, the total content ratio of Resin (A) and Resin (B) in the whole photopolymerizable components was 60% by mass, and the total content ratio of Resin (B) and Resin (C) was 70%. In addition, in Example 33, when the content ratio of the whole photopolymerizable components was 100% by mass, the content ratio of the photoinitiator was 1% by mass. That is, only the content ratios of Resin (A) to Resin (D) in Example 33 were different from those in Example 31.

[0765] As shown in Table 5, the viscosity of the ultraviolet curable acrylic resin for imprinting in Example 33 was 19.13 mPa·s. When the ultraviolet curable acrylic resin for imprinting in Example 33 was compared with the ultraviolet curable acrylic resin for imprinting in Example 31, the total content ratio of Resin (B) and Resin (C) was high, and the content ratio of Resin (D) was low. Therefore, it was speculated that the viscosity of the ultraviolet curable acrylic resin for imprinting in Example 33 was lower than the viscosity of the ultraviolet curable acrylic resin for imprinting in Example 31.

[0766] As shown in Table 6, the YI value of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 was 1.5. From the above results, it was confirmed that even when the cured product of Example 33 was heat-treated, a low YI value could be maintained. When the ultraviolet curable acrylic resin for imprinting in Example 33 was compared with the ultraviolet curable acrylic resin for imprinting in Example 31, the total content ratio of Resin (A) and Resin (B) was high. Therefore, it was speculated that the YI value of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 was lower than the YI value of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 31.

[0767] As shown in Table 6, the average transmittance of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 with respect to light in the wavelength range of 430 nm or more and 680 nm or less before the heat treatment was 92.5%, and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less before the heat treatment was 91.7%. In addition, the average transmittance of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 with respect to light in the wavelength range of 430 nm or more and 680 nm or less after the heat treatment was 92.4%, and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less after the heat treatment was 91.8%.

[0768] In the cured product of Example 33, the difference ΔA in the average transmittance of light in the wavelength range of 430 nm or more and 680 nm or less before and after the heat treatment (average transmittance before heat treatment - average transmittance after heat treatment) became -0.1%. In the cured product of Example 33, 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 the heat treatment became +0.1%. Based on the above results, it was confirmed that even when the cured product of Example 33 was heat-treated, 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. When the ultraviolet curable acrylic resin for imprinting in Example 33 was compared with the ultraviolet curable acrylic resin for imprinting in Example 31, the total content ratio of resin (A) and resin (B) was high. Therefore, it was speculated that the difference ΔA in the average transmittance of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 was smaller than the difference ΔA in the average transmittance of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 31.

[0769] As shown in Table 6, the storage modulus of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 at 30 °C was 2.1×10 9 Pa. The storage modulus of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 at 120 °C was 7.1×10 8 Pa. The storage modulus of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 at 130 °C was 5.9×10 8 Pa. The storage modulus of the cured product of the ultraviolet curable acrylic resin for imprinting in Example 33 at 140 °C was 5.0×10 8 Pa.

[0770] The change rate of the storage modulus at 120 °C relative to the storage modulus at 30 °C (storage modulus at 120 °C / storage modulus at 30 °C × 100%) of the cured product of Example 33 was 33.4%. The change rate of the storage modulus at 130 °C relative to the storage modulus at 30 °C (storage modulus at 130 °C / storage modulus at 30 °C × 100%) of the cured product of Example 33 was 27.8%. The change rate of the storage modulus at 140 °C relative to the storage modulus at 30 °C (storage modulus at 140 °C / storage modulus at 30 °C × 100%) of the cured product of Example 33 was 23.5%. Based on the above results, it was confirmed that the cured product of Example 33 had a high storage modulus of 2.1×10 9 Pa before the empirical heat treatment. In addition, it was also confirmed that even when the cured product of Example 33 was subjected to heat treatment, the decrease in the storage modulus was suppressed.

[0771] As shown in Table 6, the glass transition temperature Tg of the cured product of the imprinting photocurable acrylic resin of Example 33 was 126.1 °C. Based on the above results, it was confirmed that the cured product of Example 33 had a high glass transition temperature Tg.

[0772] [Example 34]

[0773] As shown in Table 5, in Example 34, as the photopolymerizable components, it only included resin (A), resin (B), and resin (C), and also included a photopolymerization initiator. Resin (A), resin (B), resin (C), and the photopolymerization initiator were the same as those in Example 31. In Example 34, the content ratio of resin (A) in the whole photopolymerizable components was 40% by mass, the content ratio of resin (B) was 30% by mass, and the content ratio of resin (C) was 30% by mass. That is, in Example 34, the total content ratio of resin (A) and resin (B) in the whole photopolymerizable components was 70% by mass, and the total content ratio of resin (B) and resin (C) was 60%. In addition, in Example 34, when the content ratio of the whole photopolymerizable components was 100% by mass, the content ratio of the photopolymerization initiator was 1% by mass. That is, different from Examples 31 to 33, Example 34 did not contain resin (D).

[0774] As shown in Table 5, the viscosity of the imprinting photocurable acrylic resin of Example 34 was 15.07 mPa·s. Compared with the imprinting photocurable acrylic resins of Examples 31 to 33, the imprinting photocurable acrylic resin of Example 34 did not include resin (D). Thus, it was speculated that the viscosity of the imprinting photocurable acrylic resin of Example 34 was lower than that of the imprinting photocurable acrylic resins of Examples 31 to 33.

[0775] As shown in Table 6, the YI value of the cured product of the UV-curable acrylic resin for imprinting in Example 34 was 1.3. From the above results, it was confirmed that even when the cured product of Example 34 was heat-treated, a low YI value could be maintained. When the UV-curable acrylic resin for imprinting in Example 34 was compared with the UV-curable acrylic resin for imprinting in Example 31, the total content ratio of resin (A) and resin (B) was high. Therefore, it was speculated that the YI value of the cured product of the UV-curable acrylic resin for imprinting in Example 34 was lower than that of the cured product of the UV-curable acrylic resin for imprinting in Example 31.

[0776] As shown in Table 6, the average transmittance of the cured product of the UV-curable acrylic resin for imprinting in Example 34 with respect to light in the wavelength range of 430 nm or more and 680 nm or less before heat treatment was 91.4%, and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less before heat treatment was 90.5%. In addition, the average transmittance of the cured product of the UV-curable acrylic resin for imprinting in Example 34 with respect to light in the wavelength range of 430 nm or more and 680 nm or less after heat treatment was 91.8%, and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less after heat treatment was 91.2%.

[0777] In the cured product of Example 34, the difference ΔA (average transmittance before heat treatment - average transmittance after heat treatment) in the average transmittance with respect to light in the wavelength range of 430 nm or more and 680 nm or less before and after heat treatment was +0.3%. In the cured product of Example 34, the difference ΔA in the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less before and after heat treatment was +0.7%. From the above results, it was confirmed that even when the cured product of Example 34 was heat-treated, the average transmittance with respect to light in the wavelength range of 430 nm or more and 680 nm or less and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less hardly decreased. When the UV-curable acrylic resin for imprinting in Example 34 was compared with the UV-curable acrylic resin for imprinting in Example 31, the total content ratio of resin (A) and resin (B) was high. Therefore, it was speculated that the difference ΔA in the average transmittance of the cured product of the UV-curable acrylic resin for imprinting in Example 34 was smaller than that of the cured product of the UV-curable acrylic resin for imprinting in Example 31.

[0778] As shown in Table 6, the storage modulus of the cured product of the UV-curable acrylic resin for imprinting in Example 34 at 30 °C was 2.2×10 9 Pa. The storage modulus of the cured product of the UV-curable acrylic resin for imprinting in Example 34 at 120 °C was 3.9×108 Pa. The storage modulus of the cured product of the photocurable acrylic resin for imprinting in Example 34 at 130 °C was 3.1×10 8 Pa. The storage modulus of the cured product of the photocurable acrylic resin for imprinting in Example 34 at 140 °C was 2.6×10 8 Pa.

[0779] The rate of change of the storage modulus of the cured product of Example 34 at 120 °C with respect to the storage modulus at 30 °C (storage modulus at 120 °C / storage modulus at 30 °C × 100%) was 17.8%. The rate of change of the storage modulus of the cured product of Example 34 at 130 °C with respect to the storage modulus at 30 °C (storage modulus at 130 °C / storage modulus at 30 °C × 100%) was 14.0%. The rate of change of the storage modulus of the cured product of Example 34 at 140 °C with respect to the storage modulus at 30 °C (storage modulus at 140 °C / storage modulus at 30 °C × 100%) was 11.9%. From the above results, it was confirmed that the cured product of Example 34 had a high storage modulus of 2.2×10 9 Pa before the heat treatment was carried out. In addition, it was also confirmed that even when the heat treatment was carried out on the cured product of Example 34, the decrease in the storage modulus was suppressed. In addition, the photocurable acrylic resin for imprinting in Example 34 did not contain resin (D) as compared with the photocurable acrylic resin for imprinting in Example 32. Thus, it was speculated that the rate of change of the storage modulus of the cured product of the photocurable acrylic resin for imprinting in Example 34 was less than the rate of change of the storage modulus of the cured product of the photocurable acrylic resin for imprinting in Example 32.

[0780] As shown in Table 6, the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprinting in Example 34 was 115.5 °C. From the above results, it was confirmed that the cured product of Example 34 had a high glass transition temperature Tg. In addition, the photocurable acrylic resin for imprinting in Example 34 did not contain resin (D) as compared with the photocurable acrylic resin for imprinting in Example 32. Thus, it was speculated that the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprinting in Example 34 was lower than the glass transition temperature Tg of the cured product of the photocurable acrylic resin for imprinting in Example 32.

[0781]

Table 7

[0782] [Table 7]

[0783]

[0784]

[0785]

Table 8

[0786] [Table 8]

[0787]

[0788] [Example 35]

[0789] As shown in Table 7, in Example 35, as the photopolymerizable components, it only includes resin (A), resin (B), resin (C), and resin (D), and also includes a photoinitiator. Resin (A), resin (B), resin (C), resin (D), and the photoinitiator are the same as those in Example 31. In Example 35, the content ratio of resin (A) in the whole photopolymerizable components is 30% by mass, the content ratio of resin (B) is 30% by mass, the content ratio of resin (C) is 30% by mass, and the content ratio of resin (D) is 10% by mass. That is to say, in Example 35, the total content ratio of resin (A) and resin (B) in the whole photopolymerizable components is 60% by mass, and the total content ratio of resin (B) and resin (C) is 60%. In addition, in Example 35, when the content ratio of the whole photopolymerizable components is 100% by mass, the content ratio of the photoinitiator is 1% by mass. That is to say, only the content ratios of resin (B) and resin (D) in Example 35 are different from those in Example 31.

[0790] As shown in Table 7, the viscosity of the imprinting photocurable acrylic resin of Example 35 is 18.97 mPa·s. When comparing the imprinting photocurable acrylic resin of Example 35 with that of Example 31, the total content ratio of resin (B) and resin (C) is high, and the content ratio of resin (D) is low. Thus, it is speculated that the viscosity of the imprinting photocurable acrylic resin of Example 35 is lower than that of the imprinting photocurable acrylic resin of Example 31.

[0791] As shown in Table 8, the YI value of the cured product of the imprinting photocurable acrylic resin of Example 35 is 1.2. According to the above results, it is confirmed that even if the cured product of Example 35 is subjected to heat treatment, a low YI value can be maintained.

[0792] As shown in Table 8, the average transmittance of the cured product of the imprinting photocurable acrylic resin of Example 35 with respect to light in the wavelength range of 430 nm or more and 680 nm or less before heat treatment is 91.5%, and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less before heat treatment is 90.6%. In addition, the average transmittance of the cured product of the imprinting photocurable acrylic resin of Example 35 with respect to light in the wavelength range of 430 nm or more and 680 nm or less after heat treatment is 91.7%, and the average transmittance with respect to light in the wavelength range of 430 nm or more and 510 nm or less after heat treatment is 91.2%.

[0793] In the cured product of Example 35, the difference ΔA 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 (average transmittance before heat treatment - average transmittance after heat treatment) becomes +0.2%. In the cured product of Example 35, 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 becomes +0.6%. Based on the above results, it was confirmed that even when the cured product of Example 35 was heat-treated, 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.

[0794] As shown in Table 8, the storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 35 at 30 °C was 2.0×10 9 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 35 at 120 °C was 8.6×10 8 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 35 at 130 °C was 7.8×10 8 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 35 at 140 °C was 7.2×10 8 Pa.

[0795] The change rate of the storage modulus at 120 °C with respect to the storage modulus at 30 °C (storage modulus at 120 °C / storage modulus at 30 °C × 100%) of the cured product of Example 35 became 43.3%. The change rate of the storage modulus at 130 °C with respect to the storage modulus at 30 °C (storage modulus at 130 °C / storage modulus at 30 °C × 100%) of the cured product of Example 35 became 39.5%. The change rate of the storage modulus at 140 °C with respect to the storage modulus at 30 °C (storage modulus at 140 °C / storage modulus at 30 °C × 100%) of the cured product of Example 35 became 36.3%. Based on the above results, it was confirmed that before the heat treatment, the cured product of Example 35 had a high storage modulus of 2.0×10 9 Pa. In addition, it was also confirmed that even when the cured product of Example 35 was heat-treated, the decrease in the storage modulus was suppressed.

[0796] As shown in Table 8, the glass transition temperature Tg of the cured product of the imprinting photocurable acrylic resin of Example 35 was 181.3 °C. Based on the above results, it was confirmed that the cured product of Example 35 had a high glass transition temperature Tg.

[0797] [Example 36]

[0798] As shown in Table 7, in Example 36, as the photopolymerizable components, it only includes resin (A), resin (B), resin (C), and resin (D), and also includes a photopolymerization initiator. Resin (A), resin (B), resin (C), and the photopolymerization initiator are the same as those in Example 35. In Example 36, as resin (D), M-9050 manufactured by Toagosei Co., Ltd. is used. In Example 36, the content ratios of resin (A), resin (B), resin (C), and resin (D) in the whole photopolymerizable components are the same as those in Example 35. In addition, in Example 36, when the content ratio of the whole photopolymerizable components is 100% by mass, the content ratio of the photopolymerization initiator is 1% by mass. That is to say, Example 36 is only different from Example 35 in resin (D).

[0799] As shown in Table 7, the viscosity of the imprinting photocurable acrylic resin in Example 36 is 23.02 mPa·s. The viscosity of resin (D) in Example 36 is higher than that of resin (D) in Example 35. Thus, it is speculated that the viscosity of the imprinting photocurable acrylic resin in Example 36 is higher than that of the imprinting photocurable acrylic resin in Example 35.

[0800] As shown in Table 8, the YI value of the cured product of the imprinting photocurable acrylic resin in Example 36 is 0.8. According to the above results, it is confirmed that even if the cured product of Example 36 is subjected to a heat treatment, a low YI value can be maintained. In addition, it can be seen that since the YI values of the cured products of Example 35 and Example 36 are almost the same, even if resin (D) is a different substance, the cured product of the imprinting photocurable acrylic resin can maintain a low YI value.

[0801] As shown in Table 8, the average transmittance of the cured product of the imprinting photocurable acrylic resin in Example 36 for light in the wavelength range of 430 nm or more and 680 nm or less before the heat treatment is 92.2%, and the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less before the heat treatment is 92.0%. In addition, the average transmittance of the cured product of the imprinting photocurable acrylic resin in Example 36 for light in the wavelength range of 430 nm or more and 680 nm or less after the heat treatment is 92.6%, and the average transmittance for light in the wavelength range of 430 nm or more and 510 nm or less after the heat treatment is 92.2%. It can be seen that since the average transmittances of the cured products of Example 35 and Example 36 are almost the same, even if resin (D) is a different substance, the cured product of the imprinting photocurable acrylic resin can maintain a high average transmittance.

[0802] In the cured product of Example 36, the difference ΔA in the average transmittance of light in the wavelength range of 430 nm or more and 680 nm or less before and after the heat treatment (average transmittance before the heat treatment - average transmittance after the heat treatment) becomes +0.4%. In the cured product of Example 36, 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 the heat treatment becomes +0.2%. Based on the above results, it was confirmed that even when the cured product of Example 36 was heat-treated, 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. In addition, it was found that since the difference ΔA in the average transmittance of the cured product of Example 35 and the cured product of Example 36 was almost negligible, even if Resin (D) was a different substance, the average transmittance of the cured product of the imprinting photocurable acrylic resin hardly decreased even when heat-treated.

[0803] As shown in Table 8, the storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 36 at 30 °C was 2.2×10 9 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 36 at 120 °C was 8.1×10 8 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 36 at 130 °C was 7.3×10 8 Pa. The storage modulus of the cured product of the imprinting photocurable acrylic resin of Example 36 at 140 °C was 6.7×10 8 Pa. It was found that since the storage moduli of the cured products of Example 35 and Example 36 were almost the same, the cured product of the imprinting photocurable acrylic resin had a high storage modulus even if Resin (D) was a different substance.

[0804] The rate of change of the storage modulus of the cured product of Example 36 at 120 °C with respect to the storage modulus at 30 °C (storage modulus at 120 °C / storage modulus at 30 °C × 100%) became 37.1%. The rate of change of the storage modulus of the cured product of Example 36 at 130 °C with respect to the storage modulus at 30 °C (storage modulus at 130 °C / storage modulus at 30 °C × 100%) became 33.6%. The rate of change of the storage modulus of the cured product of Example 36 at 140 °C with respect to the storage modulus at 30 °C (storage modulus at 140 °C / storage modulus at 30 °C × 100%) became 30.8%. Based on the above results, it was confirmed that before the heat treatment, the cured product of Example 36 had 2.2×10 9Pa has a high storage modulus. In addition, it was also confirmed that even when the cured product of Example 36 was heat-treated, the decrease in the storage modulus was suppressed. Furthermore, it was found that since the change rates of the storage moduli of the cured products of Example 35 and Example 36 were almost the same, even if Resin (D) was a different substance, the decrease in the storage modulus of the cured product of the imprinting photocurable acrylic resin was suppressed even when heat-treated.

[0805] As shown in Table 8, the glass transition temperature Tg of the ...

Claims

1. A photocurable acrylic resin for imprinting, containing a photopolymerizable component, characterized in that, the photopolymerizable component includes resin (A) and resin (B), resin (A) is (octahydro-4,7-methano-1H-indenediyl)bis(methylene) diacrylate, resin (B) is a difunctional acrylate monomer having a viscosity of 10 mPa·s or less at 25 °C, the content ratio of resin (A) relative to the whole photopolymerizable component is 20% by mass or more and 40% by mass or less, the total content ratio of resin (A) and resin (B) relative to the whole photopolymerizable component is 70% by mass or less.

2. The photocurable acrylic resin for imprinting according to claim 1, characterized in that, the viscosity of the photocurable acrylic resin for imprinting at 25 °C is 35 mPa·s or less.

3. The photocurable acrylic resin for imprinting according to claim 1, characterized in that, the photopolymerizable component further includes resin (C), resin (C) is an acrylate monomer having a viscosity of 10 mPa·s or less at 25 °C, the total content ratio of resin (B) and resin (C) relative to the whole photopolymerizable component is 50% by mass or more and 70% by mass or less.

4. The photocurable acrylic resin for imprinting according to claim 3, characterized in that, resin (C) is a monofunctional acrylate monomer.

5. The photocurable acrylic resin for imprinting according to claim 4, characterized in that, resin (C) is isobornyl acrylate.

6. The photocurable acrylic resin for imprinting according to claim 1, characterized in that, the photopolymerizable component further includes resin (D), resin (D) is an acrylate monomer having three or more functional groups, the content ratio of resin (D) relative to the whole photopolymerizable component is more than 0% by mass and 20% by mass or less.

7. The photocurable acrylic resin for imprinting according to claim 6, characterized in that, resin (D) is selected from one or more of the group consisting of trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and polyfunctional polyester acrylate.

8. The photocurable acrylic resin for imprinting according to claim 1, characterized in that, resin (B) is a difunctional acrylate monomer in which acryloyl groups are respectively bonded to both ends of a linear structure composed of a hydrocarbon group, or is a difunctional acrylate monomer in which acryloyl groups are respectively bonded to both ends of a linear structure having an ether bond.

9. The photocurable acrylic resin for imprinting according to claim 8, characterized in that, resin (B) is a difunctional acrylate monomer represented by the following chemical formula (I), in the chemical formula (I), n is an integer of 1 or more and 9 or less, CH2=CHCOO(CH2) n OOCCH=CH2…(I).

10. The photocurable acrylic resin for imprinting according to claim 9, characterized in that, in the chemical formula (I), n is an integer of 6 or more and 9 or less.

11. The photocurable acrylic resin for imprinting according to claim 10, characterized in that, in the chemical formula (I), n is 6 or 9.

12. The photocurable acrylic resin for imprinting according to claim 1, wherein after the cured product of the photocurable acrylic resin for imprinting is maintained at 120 °C for 500 hours, the YI value of the cured product is 3 or less.

13. The photocurable acrylic resin for imprinting according to claim 1, wherein The storage modulus of the cured product of the imprinting photocurable acrylic resin at 30 °C is 1.6×10 9 Pa or more. The storage modulus of the cured product at 120 °C is 3.9×10 8 Pa or more.

14. The photocurable acrylic resin for imprinting according to claim 1, wherein after the cured product of the photocurable acrylic resin for imprinting is maintained at 120 °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 is 90% or more.

15. The photocurable acrylic resin for imprinting according to claim 1, wherein the photocurable acrylic resin for imprinting further contains a photoinitiator for polymerizing the photopolymerizable component.

Images