WO2020071257A1 - Wire-grid polarizer, polarizing plate, and video display device - Google Patents

Abstract

This wire-grid polarizer has, on the surface thereof, a light-transmissive substrate on which parallel protruding ridges are formed, and a metal layer covering a side surface of each protruding ridge, wherein, in a cross-section perpendicular to the lengthwise direction of the protruding ridges, the height of each protruding ridge from the bottom to the top thereof is 80-125 nm, and the ratio Wh/Wm is 2.2-3.0 and the ratio Wb/Wm is 1.5-2.1, where Wm is the minimum thickness of the metal layer, Wb is the maximum thickness of the metal layer further toward the bottom in comparison to a location at one-half the height of the corresponding protruding ridge, and Wh is the maximum thickness of the metal layer present further on the opposite side from the bottom side in comparison to the top of the corresponding protruding ridge.

Description

Wire grid polarizer, polarizing plate, image display

The present invention relates to a wire grid polarizer, a polarizing plate including the wire grid polarizer, and an image display device.

The wire grid polarizer has a structure in which a plurality of fine metal wires are arranged parallel to each other on a light transmitting substrate. When the pitch of the thin metal wire is sufficiently shorter than the wavelength of the incident light, a component of the incident light having an electric field vector orthogonal to the thin metal wire (that is, p-polarized light) is transmitted and a component having an electric field vector parallel to the thin metal wire. (Ie, s-polarized light) is reflected.

When the light is separated into p-polarized light and s-polarized light by a wire grid polarizer, it is desirable that the obtained light does not include components other than the desired polarized light. For example, in a polarization beam splitter in a projector, it is required that Rs / Rp, which is the ratio of the reflectance Rs of s-polarized light to the reflectance Rp of p-polarized light, be high. By increasing the s-polarized light and decreasing the p-polarized light contained in the reflected light, Rs / Rp can be increased.

Patent Documents 1 and 2 disclose a wire grid type polarizing plate in which convex lines and concave grooves are alternately provided on the surface of a base material, and metal wires are provided so as to cover a side surface on one side of the convex line and a top of the convex line. Is described.
In Patent Document 1, the cross-sectional shape of the ridge is substantially rectangular. In Patent Document 2, the cross-sectional shape of the concave groove is substantially rectangular, and the width of the metal wire on the side surface of the ridge is substantially uniform.

Japanese Patent No. 5710151 Japanese Patent No. 5442344

In the structures of Patent Documents 1 and 2, the height of Rs / Rp may be insufficient.
An object of one embodiment of the present invention is to provide a wire grid polarizer having a high ratio of Rs / Rp, a polarizing plate including the wire grid polarizer, and an image display device.

The present invention has the following aspects.
[1] A light-transmitting substrate having mutually parallel ridges formed at a predetermined pitch on a surface, and a metal layer made of a metal or a metal compound provided on the surface of the light-transmitting substrate. The cross-sectional shape of the ridge, which is orthogonal to the length direction, has a width that gradually decreases toward the top, and at least the first side and the second side sandwich the top of the ridge. The entire side surface is covered with the metal layer, and the second side surface has an exposed surface that is not covered with the metal layer. The height from the bottom to the top of the ridge is 80 to 125 nm, the minimum value of the thickness of the metal layer covering the first side surface in the width direction of the ridge is Wm, and the minimum from the bottom to the top of the ridge is The metal layer covering the first side surface on the bottom side with respect to a half of the height of the metal layer The maximum value of the thickness in the width direction of the ridge is Wb, and the maximum value of the thickness of the metal layer present on the side opposite to the bottom side from the top of the ridge is Wh. Wherein the ratio of the Wh to the Wm is 2.2 to 3.0, and the ratio of the Wb to the Wm is 1.5 to 2.1.
[2] The wire grid polarizer according to [1], wherein a ratio of the Wh to the Wb is 1.4 or less.
[3] The wire grid polarizer according to [1] or [2], further comprising a resin layer covering the light transmitting substrate and the metal layer.
[4] The wire grid polarizer of [3], wherein the height Hg from the bottom to the top of the ridge and the refractive index n of the resin layer at a wavelength of 589.3 nm satisfy the following expression 1.
450 ≦ 4 × n × Hg ≦ 650 Equation 1
[5] In a graph obtained by the following measurement method, in which the x-axis is wavelength and the y-axis is Rs / Rp, four straight lines represented by x = 450 nm, x = 451 nm, y = 0, and y = 1 Assuming that the area of the enclosed rectangle is 1, the relative area S1 of a region surrounded by four lines represented by x = 450 nm, x = 650 nm, y = 0, and y = Rs / Rp is 7000 or more. , [3] or [4].
Measuring method: A wire grid type polarizer is sandwiched between two antireflection substrates having a reflectance of 0.7% or less at a wavelength of 450 to 650 nm, an incident angle of 5 °, a measuring wavelength of 450 to 650 nm, and a wavelength interval of 1 nm. Under the conditions, the s-polarized light reflectance and the p-polarized light reflectance are measured, respectively, and Rs / Rp, which is the ratio of the s-polarized light reflectance to the p-polarized light reflectance, is determined. The x-axis is wavelength, and the y-axis is Rs / Rp. Create
[6] A light-transmitting substrate having mutually parallel ridges formed at a predetermined pitch on a surface, and a metal layer made of a metal or a metal compound provided on the surface of the light-transmitting substrate. The cross-sectional shape of the ridge, which is orthogonal to the length direction, has a width that gradually decreases toward the top, and at least the first side and the second side sandwich the top of the ridge. The entire side surface is covered with the metal layer, and the second side surface has an exposed surface that is not covered with the metal layer, and has a resin layer covering the light transmitting substrate and the metal layer. Then, in a graph obtained by the following measurement method, in which the x-axis is wavelength and the y-axis is Rs / Rp, it is surrounded by four straight lines represented by x = 450 nm, x = 451 nm, y = 0 and y = 1. When the area of the obtained rectangle is 1, x = 450 nm, x = 650 nm, A wire grid polarizer, wherein a relative area S1 of a region surrounded by four lines represented by y = 0 and y = Rs / Rp is 7000 or more.
Measuring method: A wire grid type polarizer is sandwiched between two antireflection substrates having a reflectance of 0.7% or less at a wavelength of 450 to 650 nm, an incident angle of 5 °, a measuring wavelength of 450 to 650 nm, and a wavelength interval of 1 nm. Under the conditions, the s-polarized light reflectance and the p-polarized light reflectance are measured, respectively, and Rs / Rp, which is the ratio of the s-polarized light reflectance to the p-polarized light reflectance, is determined. The x-axis is wavelength, and the y-axis is Rs / Rp. Create
[7] A second support having a first support on the back surface of the light transmissive substrate, and a pressure-sensitive adhesive on a surface of the resin layer opposite to the light transmissive substrate side The wire grid polarizer according to any one of [3] to [6], comprising:
[8] A first support is provided on the back surface of the light transmissive substrate, and a refractive index adjustment layer is provided on a surface of the resin layer opposite to the light transmissive substrate side, [3]. A wire grid polarizer according to any one of [6] to [6].
[9] A polarizing plate including the wire grid polarizer according to any one of [1] to [8].
[10] An image display device including the wire grid polarizer according to any one of [1] to [8].

[11] A light-transmitting substrate in which mutually parallel ridges and grooves are alternately formed at a predetermined pitch on a surface, and a metal made of a metal or a metal compound provided on the surface of the light-transmitting substrate And a layer,
The cross-sectional shape of the ridge, perpendicular to the length direction, the width gradually decreases toward the top,
Of the first side surface and the second side surface sandwiching the top of the ridge, at least the entire surface of the first side surface is covered with the metal layer, and the second side surface is covered with the metal layer. Wire-grid polarizer with unexposed exposed surface.
[12] The wire grid polarizer of [11], wherein a cross-sectional shape of the concave groove orthogonal to the length direction has a tapered surface whose groove width gradually decreases toward a bottom.
[13] The wire grid polarizer according to [11] or [12], wherein a cross-sectional shape of the ridges perpendicular to the length direction has a main side surface with a constant tangent inclination.
[14] The wire grid polarizer according to any one of [11] to [13], further comprising a resin layer covering the light transmitting substrate and the metal layer.
[15] The wire grid polarizer of [14], wherein a part or all of the space between the adjacent ridges is filled with the resin layer.
[16] A second support having a first support on the back surface of the light transmissive substrate, and a pressure-sensitive adhesive on a surface of the resin layer opposite to the light transmissive substrate side The wire grid polarizer according to [14] or [15], comprising:
[17] A first support is provided on the back surface of the light transmitting substrate, and a refractive index adjusting layer is provided on a surface of the resin layer opposite to the light transmitting substrate side, [14]. Or the wire grid polarizer of [15].
[18] A polarizing plate including the wire grid polarizer according to any one of [11] to [17].
[19] An image display device including the wire grid polarizer according to any one of [11] to [17].

The wire grid polarizer of the above embodiment has a high ratio of Rs / Rp.
The polarizing plate of the above embodiment has a high ratio of Rs / Rp.
The image display device of the above aspect includes a polarizer having a high Rs / Rp ratio.

FIG. 2 is a top view schematically showing the first embodiment of the wire grid polarizer. It is sectional drawing which shows 1st Embodiment of a wire grid type polarizer typically. It is sectional drawing explaining the measuring method of s-polarized light reflectance and p-polarized light reflectance. It is a figure explaining the measuring method of relative area S1. It is sectional drawing which shows 2nd Embodiment of a wire grid type polarizer typically. It is sectional drawing which shows an example of the manufacturing process of a wire grid type polarizer. It is sectional drawing which shows an example of the manufacturing process of a wire grid type polarizer. It is sectional drawing which shows another example of the manufacturing process of a wire grid type polarizer. It is sectional drawing which shows another example of the manufacturing process of a wire grid type polarizer. It is sectional drawing which shows another example of the manufacturing process of a wire grid type polarizer. It is sectional drawing which shows 3rd Embodiment of a wire grid type polarizer typically. It is sectional drawing which shows 4th Embodiment of a wire grid type polarizer typically. It is sectional drawing which shows 5th Embodiment of a wire grid polarizer typically. It is sectional drawing which shows 6th Embodiment of a wire grid type polarizer typically. It is explanatory drawing of the length measurement method of Hg, Wh, Wm, Wb in a TEM image. 9 is a graph showing measurement results of Rs / Rp in Examples 1 to 7. FIG. 13 is a cross-sectional view schematically illustrating a wire grid polarizer of Example 10. It is a graph which shows the simulation result of Rp in a reference example. It is a graph which shows the simulation result of Rs in a reference example. It is a graph which shows the simulation result of Rp in a reference example. It is a graph which shows the simulation result of Rs in a reference example. It is a graph which shows the simulation result of Rp in a reference example. It is a graph which shows the simulation result of Rs in a reference example. It is a graph which shows the simulation result of Rp in a reference example. It is a graph which shows the simulation result of Rs in a reference example. 4 is a scanning electron microscope image of a cross section of the light transmitting substrate obtained in Production Example 1. 3 is a scanning electron microscope image of a cross section of the wire grid polarizer obtained in Production Example 1.

The following term definitions apply throughout the present description and claims.
The numerical range represented by “to” means a numerical range in which the lower and upper limits are the numerical values before and after.
“Refractive index” means the refractive index for light having a wavelength of 589.3 nm.

<First embodiment>
FIG. 1A is a top view schematically illustrating a first embodiment of a wire grid polarizer according to the present invention. FIG. 1B is a sectional view taken along line PQ of FIG. 1A. 1A and 1B, reference numeral 1 denotes a light-transmitting substrate, 2 denotes a metal layer, 11 denotes a ridge, and 11a denotes a top of the ridge 11. In FIG. 1A, only the ridgeline of the top 11a is shown, and other members are omitted. Hereinafter, the length direction of the ridge 11 is referred to as a Z direction, the width direction of the ridge 11 in a plane perpendicular to the Z direction is referred to as an X direction, and the height direction of the ridge 11 in a plane perpendicular to the Z direction is referred to as a Y direction. . The X direction and the Y direction are orthogonal.

FIGS. 1A and 1B are schematic diagrams based on design values. In an actual wire grid polarizer, a shape unavoidable in manufacturing and a nonuniform thickness of a metal layer occur. In this specification, the dimension of each part of the wire grid polarizer is an average value of measured values at arbitrary five points in a scanning electron microscope image or a transmission electron microscope image of a cross section orthogonal to the Z direction.

The light-transmitting substrate 1 is light-transmitting in the wavelength range in which the wire grid polarizer is used. The light transmittance means that the transmittance is 80% or more.

使用 The working wavelength range of the wire grid polarizer is preferably in the range of 300 to 2000 nm, more preferably 400 to 1500 nm, and still more preferably 400 to 1000 nm.

材料 Examples of the material of the light-transmitting substrate 1 include a light-curing resin, a thermosetting resin, a thermoplastic resin, and glass. From the viewpoint that the ridges 11 can be formed by the imprint method, a photocurable resin or a thermosetting resin is preferable. In particular, a photocurable resin is preferable in terms of excellent workability, heat resistance, and durability. As the photocurable resin, a cured product obtained by photocuring a photocurable composition that can be photocured by photoradical polymerization is preferable from the viewpoint of productivity.

は The refractive index of the light-transmitting substrate 1 is preferably from 1.1 to 1.6, more preferably from 1.2 to 1.59, even more preferably from 1.25 to 1.58.

(4) The photocurable composition is, for example, a composition containing a monomer, a photopolymerization initiator, a solvent, and optional additives (for example, a surfactant and a polymerization inhibitor). For example, a photocurable composition described in paragraphs 0029 to 0074 of WO 2007/116972 can be used.

材料 The material of the metal layer 2 may be a conductive metal material, and is preferably a corrosion-resistant material. A metal or metal compound can be exemplified.

For example, a simple substance of a metal, an alloy, a metal containing a dopant or an impurity may be mentioned. Specifically, aluminum, silver, chromium, magnesium, an aluminum alloy, and a silver alloy can be exemplified. These can be used alone or in combination of two or more.

The material of the metal layer 2 is preferably aluminum, an aluminum-based alloy, silver, a silver-based alloy, chromium, or magnesium from the viewpoint of high reflectance to visible light, low absorption of visible light, and high conductivity. Aluminum-based alloys and silver-based alloys are more preferred. These can be used alone or in combination of two or more.

In the present embodiment, a plurality of ridges 11 are formed on the surface of the light-transmitting substrate 1. The plurality of ridges 11 extend in the Z direction and are parallel to each other.

形状 The shape (cross-sectional shape) of the ridge 11 in a cross section orthogonal to the Z direction is a triangle or a substantially triangle whose width gradually decreases toward the top 11a. The top 11a of the ridge 11 is a portion having the highest height in the Y direction, and forms a line (ridge) in the Z direction. The apex angle including the apex 11a may be an acute angle or a rounded angle.

In the cross-sectional shape of the plurality of ridges 11, the portion farthest from the top 11a in the Y direction between the adjacent tops 11a is the bottom 12a. When a plane that is in contact with the bottom 12a and is orthogonal to the Y direction is defined as a reference plane B, the pitch p in the X direction of the ridge 11 on the reference plane B and the pitch p of the ridge 11 from the bottom 12a of the ridge 11 (reference plane B). The design value of the height Hg in the Y direction up to the top 11a is uniform.

Note that, in this specification, even if the design values are uniform, in an actual wire grid type polarizer, a shape inevitable in manufacturing occurs, and a variation of, for example, about 2 nm to a maximum of about 20 nm may occur. .

面 The surface from the bottom 12a to the top 11a of the ridge 11 is defined as the side of the ridge 11, and the two sides sandwiching the top 11a of the ridge 11 are defined as a first side 11b1 and a second side 11b2.

The metal layer 2 is provided so as to cover at least the entire first side surface 11b1 of the first side surface 11b1 and the second side surface 11b2 of the ridge 11. When the first side surface 11b1 of the ridge 11 is covered with the metal layer, the second side surface 11b2 near the top 11a of the ridge 11 may be covered with the metal layer 2.

The second side surface 11b2 of the ridge 11 is not entirely covered with the metal layer 2, but has an exposed surface on which the light-transmitting substrate 1 is exposed.

The wire grid polarizer of the present embodiment uses a photo-imprinting method (method according to the description of FIGS. 5A, 5B, and 6A to 6C) described later to form a ridge on the layer of the photocurable composition. Is formed to form the light-transmitting substrate 1 and the metal layer 2 is provided by a vapor deposition method.

For example, the metal layer 2 can be formed on the entire surface of the first side surface 11b1 of the ridge 11 and in the vicinity thereof by using a vacuum evaporation method. When performing vacuum deposition, an oblique deposition method in which the light-transmitting substrate 1 is arranged obliquely with respect to the deposition source may be used. During oblique deposition, the deposition direction may change over time.

For example, as shown in FIG. 1A and FIG. 1B, a predetermined deposition angle (for example, θ1, θ2, the unit is “°”) is orthogonal to or substantially orthogonal to the Z direction and on the first side surface 11b1 side with respect to the Y direction. )), A metal or a metal compound is vapor-deposited from a direction inclined (vapor deposition direction) to form the metal layer 2. By increasing the deposition angle over time, as shown in FIGS. 1A and 1B, the metal layer 2 near the top 11a and the bottom 12a of the first side surface 11b1 is thick, and the metal layer 2 is thin between them. A metal layer 2 having a shape having a portion is obtained. For example, the evaporation angle (θ1, θ2) can be continuously changed by a method in which the evaporation source is fixed and the light transmissive substrate 1 is evaporated while being moved in the _X0 direction. The absolute value of the change in the deposition angle (θ1, θ2) is preferably 30 ° or less.

に お い て In a cross section orthogonal to the Z direction, the minimum value of the thickness in the X direction of the metal layer 2 covering the first side surface 11b1 is Wm. The maximum value of the thickness in the X direction of the metal layer 2 covering the first side surface 11b1 on the side of the bottom 12a from the half of the height Hg of the ridge 11 is defined as Wb. The maximum value of the thickness in the X direction of the metal layer 2 existing above the top 11a of the ridge 11 (on the side opposite to the bottom 12a) is defined as Wh.

In the present embodiment, Wh / Wm representing the ratio of Wh to Wm is 2.2 to 3.0, and Wb / Wm representing the ratio of Wb to Wm is 1.5 to 2.1. Preferably, Wh / Wm is 2.2 to 2.5, and more preferably, Wh / Wm is 2.2 to 2.4. Preferably, Wb / Wm is 1.6 to 2.1, and more preferably, Wb / Wm is 1.9 to 2.1.

と It is considered that a high Rs / Rp is easily obtained when the content is within the above range. This is considered to be due to the interaction between the polarized light reflected by the metal layer 2 near the top 11a and the polarized light reflected by the metal layer 2 near the bottom 12a.

に お い て In the present embodiment, Wh / Wb representing the ratio of Wh to Wb is preferably 1.4 or less, more preferably 1.2 or less, and even more preferably 1.1 or less. When it is not more than the above upper limit, a high Rs / Rp can be obtained.

に お い て In the present embodiment, Wh is more preferably from 30 to 55 nm, even more preferably from 35 to 50 nm.

Wm is more preferably from 10 to 30 nm, even more preferably from 15 to 25 nm.

Wb is more preferably from 20 to 50 nm, even more preferably from 25 to 45 nm.

The difference between Wh and Wm is more preferably from 15 to 35 nm, even more preferably from 20 to 30 nm.

The difference between Wb and Wm is more preferably 5 to 30 nm, even more preferably 6 to 25 nm.

差 The difference between Wh and Wb is preferably 1 to 25 nm, more preferably 2 to 20 nm.

Ｙ The height Hg of the ridge 11 in the Y direction is preferably 80 to 125 nm, more preferably 85 to 120 nm, and still more preferably 90 to 115 nm.

The pitch p of the ridge 11 in the X direction is preferably from 60 to 150 nm, more preferably from 70 to 130 nm, even more preferably from 80 to 110 nm.

In this embodiment, a resin layer 31, 32 or 33 covering the light-transmitting substrate 1 and the metal layer 2 may be provided as in the third to fifth embodiments described later (see FIGS. 7 to 9).

In the present embodiment, the refractive index n of the resin layer 31, 32, or 33 at a wavelength of 589.3 nm is preferably 1.10 to 1.50, more preferably 1.15 to 1.45, and 1.20 to 1.40. Is more preferred.

When the resin layer 31, 32 or 33 is provided, it is preferable that the height Hg of the ridge 11 in the Y direction and the refractive index n of the resin layer at a wavelength of 589.3 nm satisfy the following expression 1.
450 ≦ 4 × n × Hg ≦ 650 Equation 1

を 満 た す When the above expression 1 is satisfied, a higher Rs / Rp can be obtained in the visible light region. The value of “4 × n × Hg” may be 451 to 649, 452 to 648, or 480 to 640.

According to the embodiment having the resin layer 31, 32, or 33, high Rs / Rp is easily obtained in the visible light region.

Specifically, in a graph obtained by the following measurement method, in which the x-axis is wavelength (unit: nm) and the y-axis is Rs / Rp, x = 450 nm, x = 650 nm, y = 0 and y = Rs / A wire grid polarizer having a relative area S1 of 7000 or more in a region surrounded by four lines represented by Rp is obtained. S1 is preferably 8000 or more, more preferably 10,000 or more.

Preferably, in the graph, a relative area S2 of a region surrounded by four lines represented by x = 450 nm, x = 650 nm, y = 30 and y = Rs / Rp is 2000 or more. Is obtained. S2 is more preferably 4000 or more, and still more preferably 10,000 or more.

The relative areas S1 and S2 are four straight lines represented by x = 450 nm, x = 451 nm, y = 0, and y = 1 in a graph in which the x-axis is wavelength (unit: nm) and the y-axis is Rs / Rp. It is a relative area when the area of the square surrounded by is set to 1.

大 き い The larger the values of the relative areas S1 and S2, the better the polarization separation ability of the reflected light in the visible light region.

測定 A method for measuring the relative areas S1 and S2 will be described with reference to FIGS. FIG. 2 shows a wire grid type polarized light in which the light transmissive substrate 1 and the metal layer 2 are covered with the resin layer 32 and a part of the resin layer 32 fills the entire space between the adjacent ridges 11. It is an example of a child.

As shown in FIG. 2, in a state where the wire grid type polarizer is sandwiched between two anti-reflection substrates 42 that have been subjected to anti-reflection treatment so that the reflectance at a wavelength of 450 to 650 nm is 0.7% or less, The s-polarized light reflectance and the p-polarized light reflectance are each measured. As the anti-reflection substrate 42, a glass or a film having a reflectance of 0.7% or less for p-polarized light at a wavelength of 450 to 650 nm with respect to the anti-reflection treated surface can be used.

The measurement conditions for the s-polarized light reflectance and the p-polarized light reflectance are an incident angle θ3 of 5 °, a measurement wavelength of 450 nm to 650 nm, and a wavelength interval of 1 nm. Rs / Rp at each wavelength is obtained, and a graph in which the x-axis is wavelength (unit: nm) and the y-axis is Rs / Rp is created. FIG. 3 is an example of a graph.

相 対 Based on the obtained graph, the relative areas S1 and S2 are obtained by the following method.

(1) As shown in FIG. 3, a region surrounded by four lines represented by x = 450, x = 650, y = 0, and y = Rs / Rp has a width of 1 nm in the x-axis direction. Convert to a set of rectangles.

Specifically, if the value of Rs / Rp when the wavelength is λ (nm) is r1, and the value of Rs / Rp when the wavelength is λ + 1 (nm) is r2, x = λ, x = λ + 1, y A region surrounded by four lines represented by = 0 and y = Rs / Rp is surrounded by four straight lines represented by x = λ, x = λ + 1, y = 0, and y = (r1 + r2) / 2. Convert to a rectangle. The areas of the rectangles having λ of 450 to 649 are summed to obtain a relative area S1.

(2) In the above (1), y = 0 is changed to y = 30, and the relative area S2 is obtained.

That is, a region surrounded by four lines represented by x = 450, x = 650, y = 30, and y = Rs / Rp is similarly set to x = λ, x = λ + 1, y = 30, and y = It is converted into a rectangle surrounded by four straight lines represented by (r1 + r2) / 2. The areas of the rectangles having λ of 450 to 649 are summed to obtain a relative area S2.

<Second embodiment>
FIG. 4 is a sectional view schematically showing a second embodiment of the wire grid polarizer of the present invention. In FIG. 4, reference numeral 1 denotes a light transmitting substrate, 2 denotes a metal layer, 11 denotes a ridge, and 12 denotes a concave groove.

FIG. 4 is a schematic diagram based on design values. In an actual wire grid polarizer, a shape unavoidable in manufacturing and a nonuniform metal layer thickness are produced.

In the present embodiment, a plurality of ridges 11 and a plurality of grooves 12 are alternately formed on the surface of the light-transmitting substrate 1. The plurality of ridges 11 extend in the Z direction and are parallel to each other. The plurality of concave grooves 12 extend in the Z direction and are parallel to each other.

形状 The shape (cross-sectional shape) of the ridge 11 in a cross section orthogonal to the Z direction is a triangle or a substantially triangle whose width gradually decreases toward the top 11a. The top 11a of the ridge 11 is a portion having the highest height in the Y direction, and is continuous with the Z direction to form a line. The apex angle including the apex 11a may be an acute angle or a rounded angle.

断面 The cross-sectional shape of the plurality of ridges 11 is uniform. When a plane passing through the lower end 11c of the ridge 11 and orthogonal to the Y direction is defined as a reference plane C, the width a of the ridge 11 in the X direction in the reference plane C and the pitch of the ridge 11 in the X plane in the reference plane C are defined. b and the design value of the height c in the Y direction from the reference plane C to the top 11a of the ridge 11 are uniform.

凹 In the X direction, there is a concave groove 12 between adjacent ridges 11. The portion below the lower end 11 c of the ridge 11 is the concave groove 12. The shape (cross-sectional shape) of the concave groove 12 in a cross section orthogonal to the Z direction has a tapered surface 12b whose groove width gradually decreases toward the bottom 12a. The portion having the lowest position in the Y direction is the bottom portion 12a.

高 The height in the Y direction from the reference plane C to the bottom 12a of the groove 12 to the reference plane C is defined as the depth d of the groove.

In the present embodiment, the cross-sectional shape of the concave groove 12 is a V-shape in which the inclination of the tangent to the tapered surface 12b is constant or substantially constant. The bottom 12a may be an acute angle or a rounded corner. In the present embodiment, the bottom portion 12a extends in the Z direction to form a line.

断面 The cross-sectional shape of the plurality of grooves 12 is uniform, and the depth d of the grooves 12 is uniform.

面 The surface from the lower end 11c of the ridge 11 to the top 11a of the ridge 11 is defined as the side surface of the ridge 11. The two side surfaces sandwiching the top 11a of the ridge 11 are referred to as a first side surface 11b1 and a second side surface 11b2. The surface from the lower end 11 c of the ridge 11 to the bottom 12 a of the groove 12 is defined as the side surface of the groove 12.

In the present embodiment, the ridges 11 and the concave grooves 12 are formed on the surface of the integrated light-transmitting substrate 1. That is, the top 11a of the ridge 11, the side of the ridge 11, the side of the groove 12, and the bottom 12a of the groove 12 are made of the same material.

The metal layer 2 is provided so as to cover at least the entire first side surface 11b1 of the first side surface 11b1 and the second side surface 11b2 of the ridge 11. When the first side surface 11b1 of the ridge 11 is covered with the metal layer, the second side surface 11b2 near the top 11a of the ridge 11 and the side of the concave groove 12 near the lower end 11c of the ridge 11 are covered with the metal layer 2. It may be coated.

The second side surface 11b2 of the ridge 11 is not entirely covered with the metal layer 2, but has an exposed surface on which the light-transmitting substrate 1 is exposed.

ワ イ ヤ The wire grid polarizer of this embodiment can be manufactured by the following method.

First, a light-curable composition is applied to the surface of a light-transmissive substrate, and the light-transmissible substrate is formed by forming ridges and grooves in the light-curable composition layer using a photo-imprinting method. Is prepared. After the optical imprint method, etching may be performed as necessary.

In the optical imprint method, for example, by combining electron beam drawing and etching, a mold in which a plurality of grooves are formed in parallel with each other and at a predetermined pitch is produced, and the grooves of the mold are applied to the surface of the base material. And transferring the photocurable composition to the cured photocurable composition and simultaneously photocuring the photocurable composition.

For example, a mold prepared by electron beam drawing and etching may be used as a master mold (master mold), and a child mold or a grandchild mold replicated by a photo-imprint method may be used for transfer to the photocurable composition.

The light-transmitting substrate is made of a glass plate (quartz glass plate, non-alkali glass plate, etc.) and resin (cyclic olefin resin, acrylic resin, triacetyl cellulose resin, polyimide resin, polydimethylsiloxane, transparent fluororesin). A film can be illustrated.

For example, first, as shown in FIG. 5A, an uncured photocurable composition 22 is applied to the surface of a substrate 21, and irregularities having shapes corresponding to the ridges 11 and the grooves 12 to be obtained are formed. The molded mold 23 is pressed against the photocurable composition 22. In this state, the photocurable composition is cured by irradiating radiation (for example, ultraviolet rays or electron beams), and then, as shown in FIG. 5B, the mold 23 is released to obtain the light transmissive substrate 1.

金属 A metal layer can be formed on the light transmitting substrate 1 while being integrated with the base material 21. The substrate 21 may be a support described later. If necessary, the light transmissive substrate 1 and the base material 21 may be separated before or after the formation of the metal layer.

Alternatively, as shown in FIGS. 6A and 6B, the light-transmitting substrate 1 can be manufactured by a method using a mold 24 having a different shape from the mold 23. Specifically, first, the mold 24 is pressed against the photocurable composition 22 on the base material 21 to perform photocuring, thereby forming a rectangular ridge 10 larger than the ridge 11 to be obtained. Get things. Thereafter, as shown in FIG. 6C, the ridges 10 of the cured product are etched and processed into ridges 11 having a desired shape to obtain the light-transmitting substrate 1.

ワ イ ヤ By providing the metal layer 2 on the light transmitting substrate 1 thus manufactured, the wire grid polarizer of the present embodiment can be obtained.

蒸 着 The metal layer 2 is preferably formed by vapor deposition. Examples of the vapor deposition method include a physical vapor deposition method (PVD) and a chemical vapor deposition method (CVD). A vacuum deposition method, a sputtering method, or an ion plating method is preferable. In particular, the vacuum evaporation method is preferable because the incident direction of the fine particles to be attached to the light transmitting substrate 1 can be easily controlled.

In the present embodiment, it is preferable that the metal layer 2 is deposited on the entire surface of the first side surface 11b1 of the ridge 11 and in the vicinity thereof by using an oblique evaporation method by a vacuum evaporation method.

Specifically, as shown in FIG. 4, an angle θ (unit is “°”) (evaporation angle) is orthogonal to or substantially orthogonal to the Z direction and on the side of the first side surface 11b1 with respect to the Y direction. The metal layer 2 is formed by vapor-depositing a metal or a metal compound from the direction (deposition direction).

(4) The deposition amount is controlled so that a predetermined thickness of the metal layer 2 is obtained. Specifically, the test piece is placed in the same film-forming environment as the light-transmitting substrate 1, and the deposition amount is controlled so that the thickness of the metal layer formed on the test piece becomes a target value. For example, a glass substrate is used as the test piece. The film thickness is measured by, for example, a stylus type contact film thickness meter.

According to the wire grid polarizer of the present embodiment, Rs / Rp can be increased. For example, a wire grid polarizer having Rs of 50% or more, Rp of 10% or less, and Rs / Rp of 5 or more can be realized.

The wire grid polarizer according to the present embodiment has a configuration in which the cross-sectional shape of the ridge 11 is triangular or substantially triangular, and the concave groove 12 having the tapered surface 12 b is provided between the adjacent ridges 11. When the light transmitting substrate 1 is manufactured by the manufacturing method shown in FIGS. 5A and 5B, the shape of the mold can be easily formed.

The pitch b of the ridges 11 in the X direction is preferably 150 nm or less, more preferably 130 nm or less, and even more preferably 100 nm or less. The lower limit of the pitch b is preferably 60 nm or more. The pitch b is preferably from 60 to 150 nm, more preferably from 70 to 130 nm, even more preferably from 80 to 110 nm.

Ａ a / b representing the ratio of the width a to the pitch b is preferably 0.8 or less, more preferably 0.7 or less, and still more preferably 0.5 or less. The lower limit of a / b is preferably 0.2 or more. a / b is preferably from 0.2 to 0.8, more preferably from 0.2 to 0.7, and even more preferably from 0.2 to 0.5.

高 The height c of the ridge 11 in the Y direction is preferably 125 nm or less, more preferably 120 nm or less, and even more preferably 115 nm or less. The lower limit of the height c is preferably 80 nm or more. The height c is preferably from 80 to 125 nm, more preferably from 85 to 120 nm, even more preferably from 90 to 115 nm.

深 The depth d of the concave groove 12 is preferably more than zero and 100 nm or less.

蒸 着 When forming a metal layer by oblique deposition, the deposition angle θ is preferably from 10 to 40 °, more preferably from 15 to 35 °, even more preferably from 20 to 30 °.

厚 み The thickness e of the metal layer 2 in the X direction at a position of １ ／ of the height (c + d) is preferably 20 to 60 nm, more preferably 25 to 55 nm, and further preferably 30 to 50 nm.

The ratio (a ′ / e) of the thickness e in the X direction of the metal layer 2 to the width a ′ in the X direction of the ridge 11 at a position １ ／ of the height (c + d) is preferably 0.5 to 2. .
Assuming that the cross-sectional area of the metal layer 2 in the cross section orthogonal to the Z direction is Qm and the cross-sectional area of the light-transmitting substrate 1 above the bottom 12a of the concave groove 12 is Qs, Qm / Qs is 0.2 to 5. preferable.

<Third to fifth embodiments>
7 to 9 are sectional views schematically showing third to fifth embodiments of the wire grid polarizer. The same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

In the third embodiment shown in FIG. 7, the light-transmitting substrate 1 and the metal layer 2 are covered with a resin layer 31, and a part of the resin layer 31 is formed in a part of the space between the adjacent ridges 11. Is filled. The portion of the space not filled with the resin layer 31 is an air layer.

Hereinafter, the ratio of the height f from the bottom 12a of the groove 12 to the lower end 31a of the resin layer 31 with respect to the height (c + d) from the bottom 12a of the groove 12 to the top 11a of the ridge 11 in the Y direction. Is called “embedding degree (unit is%)”.

FIGS. 7 to 9 are schematic diagrams based on design values. In an actual wire grid polarizer, when the height f from the bottom 12a of the concave groove 12 to the lower end 31a of the resin layer 31 is not uniform, the minimum value of the height f between two adjacent ridges is Is the measured value, and the average value of the measured values at any five points is the height f of the wire grid polarizer.

In the fourth embodiment shown in FIG. 8, the light-transmitting substrate 1 and the metal layer 2 are covered with the resin layer 32, and a part of the resin layer 32 fills the entire space between the adjacent ridges 11. Have been. The embedding degree in the present embodiment is 0%.

In the fifth embodiment shown in FIG. 9, the lower end 33a of the resin layer 33 covering the light transmitting substrate 1 and the metal layer 2 is located at the same position as the top 11a of the ridge 11 in the Y direction, and f = (c + d) It is. The embedding degree in the present embodiment is 100%. The space between the adjacent ridges 11 is not filled with the resin layer 33.

As shown in FIGS. 7 to 9, in order to reduce reflection at the interface between the resin layers 31, 32, and 33 and members (not shown) laminated thereon, a refractive index adjustment layer 41 is provided between them. It may be provided.

The resin layers 31, 32, and 33 have optical transparency. The refractive index of the resin layers 31, 32, and 33 at a wavelength of 589.3 nm is preferably 1.10 to 1.50, more preferably 1.15 to 1.40, and further preferably 1.20 to 1.39. When the refractive index of the resin layers 31, 32, and 33 is equal to or more than the lower limit of the above range, good resistance to an imprint process or the like is easily obtained. If it is less than the upper limit, good optical characteristics are likely to be obtained.

In the wire grid polarizers of the third to fifth embodiments, the light-transmitting substrate 1 is manufactured, the metal layer 2 is provided, and the resin layers 31, 32, and 33 are applied. It can be manufactured by a lamination method.

For example, first, the light-transmitting substrate 1 and the metal layer 2 are manufactured in the same manner as in the second embodiment.

Next, the resin layers 31, 32, and 33 are formed by, for example, a method of applying and drying a solution containing a resin, or a method of applying and drying a solution containing a resin, followed by UV curing or heat curing. At this time, the degree of embedding can be adjusted by, for example, a method of previously cleaning the surface of the metal layer by corona treatment, or a method of reducing the molecular weight of the resin to reduce the molecular size.

Thereafter, a solution containing a resin is applied on another glass substrate, dried to form a coating film (refractive index adjusting layer), and the refractive index is adjusted by a method of transferring the coating film onto the metal layer 2 or the like. The layer 41 is formed. The height g from the top 11a of the ridge 11 to the upper end of the resin layer 31 is not particularly limited.

<Sixth embodiment>
In the first to fifth embodiments, the cross-sectional shape of the ridge 11 is triangular or substantially triangular. However, as shown in FIG. 10, a trapezoid in which the top 11a is a flat surface orthogonal to the Y direction may be used. In this case, the top 11a has a band shape extending in the Z direction. If the width w of the flat surface of the top 11a in the X direction is small, the same effects as those of the first to fifth embodiments can be obtained.

(4) The width w of the flat surface of the top 11a in the X direction is preferably 40% or less, more preferably 30% or less, even more preferably 25% or less with respect to the pitch b of the ridges. The width w is zero, that is, the cross-sectional shape of the ridge 11 is most preferably a triangle or a substantially triangle.

In the second to sixth embodiments, the cross-sectional shape of the concave groove 12 is V-shaped. However, even if a flat surface orthogonal to the Y direction is present at the bottom between the tapered surfaces 12b, the second groove may be formed. The same effects as in the second to sixth embodiments can be obtained. In this case, the bottom has a band shape extending in the Z direction. The width of the bottom flat surface in the X direction is preferably 20% or more, more preferably 50% or more, even more preferably 70% or more with respect to the pitch b of the ridges.

Also, in the first embodiment, a concave groove may be formed between the ridges as in the second embodiment.

In the first to sixth embodiments, a support made of a thermoplastic resin, glass, or the like (not shown) is provided on the back surface (the surface opposite to the surface on which the ridges and grooves are provided) of the light-transmitting substrate 1. ) May be included.

From the viewpoint of the optical characteristics of the wire grid polarizer, it is preferable that a support (hereinafter, also referred to as a first support) is provided on the back surface of the light transmitting substrate 1. The difference (absolute value) in the refractive index between the support and the light transmitting substrate 1 is preferably 0.1 or less, more preferably 0.05 or less. When the difference in the refractive index between the support and the light-transmitting substrate 1 is 0.1 or less, it is easy to reduce the loss of the light amount due to the reflection at the interface.

When the resin layers 31, 32, and 33 are further provided, a support (hereinafter, also referred to as a second support) is provided on the surface of the resin layer (the surface opposite to the light-transmitting substrate 1 side). You may. The resin layer and the support (second support) may be attached with an adhesive. The materials of the first support and the second support may be the same or different.

<Application>
Suitable applications of the wire grid polarizer of the present invention include, for example, an image display device and a polarizing plate. Examples of the video display device include a liquid crystal display device and a head-up display device.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

<Measurement method>
The following measurement method was used.

[Method of measuring Hg, Wh, Wm, Wb in TEM image]
This will be described with reference to FIG.

(1) The wire grid polarizer manufactured in each example was trimmed, embedded in an epoxy resin, and cured. The cured sample (room temperature) was cut with an ultramicrotome (trade name, Ultracut EM UC 6, Leica Microsystems, using a diamond knife) to produce an ultrathin section. The thickness (set value) of the ultrathin section was 50 nm.
The prepared ultrathin section was observed using a transmission electron microscope (product name: HT7700, Hitachi High-Technologies Corporation) under the following conditions to obtain an image. FIG. 11 is an example of a TEM image.
Acceleration voltage: 100 kV, filament voltage: 27.2 V, emission current: 8.5 μA, convergent lens movable diaphragm: 2, objective movable diaphragm: 3, limited field diaphragm: 0, shooting mode: HR (high resolution).

(2) On the TEM image, any five consecutive ridges were measured, and a reference line was defined for each ridge. The reference line was a straight line that was in contact with the two bottoms sandwiching the ridge to be measured, and that had a minimum length where the bottom and the reference line were in contact. For each ridge, the direction parallel to the reference line was defined as the X direction, and the direction orthogonal thereto was defined as the Y direction.
For example, in FIG. 11, B1 is the reference line of the first ridge, and B4 is the reference line of the fourth ridge. The reference lines of each ridge may not be parallel to each other. The direction parallel to the reference line B1 is defined as the X1 direction, and the direction orthogonal thereto is defined as the Y1 direction. The direction parallel to the reference line B4 is defined as the X4 direction, and the direction orthogonal thereto is defined as the Y4 direction.

(3) For each of the five ridges, the height of the ridge in the Y direction was determined by the following method, and the average was defined as Hg (unit: nm). The average value was rounded up to the nearest decimal point (the same applies hereinafter).
For example, the height Hg1 of the first ridge was determined by the following procedure. A straight line that is parallel to the X1 direction and is in contact with the top of the ridge and has the minimum length of the portion in contact with the top is provided, and the distance from the reference line B1 to the straight line in the Y1 direction is set to be convex. It was measured as the height Hg1 of the strip.
The heights of the other ridges were determined in the same manner. For example, for the fourth ridge, a straight line that is parallel to the X4 direction and that is in contact with the top of the ridge and that has a minimum length in contact with the top is provided, and a reference line in the Y4 direction is provided. The distance from B4 to the straight line was measured as the height Hg4 of the ridge.

(4) For each of the five ridges, the maximum value of the thickness of the metal layer above the top of the ridge (opposite to the bottom side) (hereinafter, referred to as the upper maximum value) is determined for each of the five ridges by the following method. The average was determined as Wh (unit: nm).
For example, the upper-side maximum value Wh1 of the first ridge was determined by the following procedure. In the metal layer above the top of the ridge, two straight lines parallel to the Y1 direction passing through both ends of the metal layer in the X1 direction were provided. The maximum value of the distance between the two straight lines in the X1 direction was measured as the upper maximum value Wh1.
For the other ridges, the upper maximum value was determined in the same manner. For example, for the fourth ridge, two straight lines parallel to the Y4 direction are provided on the metal layer above the top of the ridge, passing through both ends of the metal layer in the X4 direction. The maximum value of the distance between the two straight lines in the X4 direction was measured as the upper maximum value Wh4.

(5) The minimum value of the thickness of the metal layer was determined for each of the five ridges by the following method, and the average was defined as Wm (unit: nm).
For example, the minimum value Wm1 of the thickness of the first ridge was determined by the following procedure. Two straight lines parallel to the Y1 direction passing through both ends of the metal layer in the X1 direction were provided. The minimum value of the distance between the two straight lines in the X1 direction was measured as the minimum value Wm1 of the thickness.
The minimum value of the thickness was determined in the same manner for other ridges. For example, as for the fourth ridge, two straight lines parallel to the Y4 direction are provided, passing through both ends of the metal layer in the X4 direction. The minimum value of the distance between the two straight lines in the X4 direction was measured as the minimum value Wm4 of the thickness.

(6) For each of the five ridges, the maximum value of the thickness of the metal layer on the bottom side from the position １ ／ of the height from the bottom to the top of each ridge (hereinafter referred to as the bottom side) The average was taken as Wb (unit: nm).
For example, the bottom-side maximum value Wb1 of the first ridge was determined by the following procedure. In the metal layer on the bottom side from the position of half the height from the bottom to the top of the ridge, two straight lines passing through both ends of the metal layer in the X1 direction and parallel to the Y1 direction were provided. The maximum value of the distance between the two straight lines in the X1 direction was measured as the bottom-side maximum value Wb1.
The bottom-side maximum value was similarly obtained for the other ridges. For example, with respect to the fourth ridge, in the metal layer on the bottom side from a position １ ／ of the height from the bottom to the top of the ridge, the two ridges pass through both ends of the metal layer in the X4 direction and are parallel to the Y4 direction. Two straight lines were provided. The maximum value of the distance between the two straight lines in the X4 direction was measured as the bottom-side maximum value Wb4.

[Method of Measuring Rs / Rp and Areas S1 and S2]
(1) As shown in FIG. 2, the s-polarized light reflectance was obtained in a state in which the wire grid polarizer manufactured in each example was sandwiched between two antireflection substrates 42 whose surfaces in contact with air were subjected to antireflection treatment. (Unit:%) and p-polarized light reflectance (unit:%) were measured. In this example, as the anti-reflection substrate 42 provided on the side where polarized light is incident, anti-reflection treated glass (hereinafter referred to as anti-reflection glass) is used, and the anti-reflection provided on the side where polarized light is emitted (transmitting side) As the base material 42, an antireflection-treated film (hereinafter, referred to as an antireflection film) was used.
The reflectance of the antireflection glass and the antireflection film was measured in advance by the following method, and it was confirmed that the reflectance was 0.7% or less.
A black paint layer was formed on the back surface of the antireflection glass, and in a state where reflection from the back surface was suppressed, p-polarized light having a wavelength of 450 to 650 nm was incident on the surface at an incident angle of 5 ° and the reflectance was measured. As a measuring device, an ultraviolet-visible spectrophotometer (UH-4150, product name of Hitachi High-Tech Science Corporation) was used. The measurement wavelength was 450 nm to 650 nm, the wavelength interval was 1 nm, the slit was fixed at 4 nm, and the scan speed was 300 nm / min.
With respect to the antireflection film, glass was bonded to the back surface via an adhesive layer to flatten the film. A black paint layer was formed on the exposed surface of the glass (the side opposite to the adhesive layer) to suppress reflection from the back surface. With respect to the obtained laminate of the antireflection film and the glass, the reflectance of the surface of the antireflection film was measured under the same conditions as those for the antireflection glass.

(2) The s-polarized light reflectance (Rs) was measured using an ultraviolet-visible spectrophotometer (product name: UH-4150, Hitachi High-Tech Science Corporation). Specifically, an attached polarizer is provided between the wire grid polarizer to be measured and the light source, and the length direction (Z direction) of the ridge of the wire grid polarizer and the absorption axis of the polarizer. Were set in orthogonal directions. Polarized light was incident on the surface side (the side on which the ridges were formed) of the wire grid polarizer, and the s-polarized light reflectance was measured. The incident angle θ3 was 5 °. The measurement wavelength was 450 nm to 650 nm, the wavelength interval was 1 nm, the slit was fixed at 4 nm, and the scan speed was 300 nm / min.

(3) In the above (2), the direction of the attached polarizer was changed to a direction in which the Z direction is parallel to the absorption axis of the polarizer. Otherwise, the p-polarized light reflectance (Rp) was measured in the same manner.

(4) Rs / Rp at each wavelength was calculated, and a graph in which the x-axis was wavelength (unit: nm) and the y-axis was Rs / Rp was created.

(5) Based on the obtained graph, the relative areas S1 and S2 were determined by the method described above.

<Preparation Example 1: Preparation of photocurable composition>
The following (1) to (4) were mixed to prepare a photocurable composition.
(1) 40 g of Monomer 1 (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-DPH, dipentaerythritol hexaacrylate)
(2) 60 g of monomer 2 (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-HD-N, hexanediol diacrylate)
(3) 4.0 g of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, IRGACURE907); and (4) a fluorine-containing surfactant (manufactured by Asahi Glass Co., Ltd., fluoroacrylate (CH ₂ ＝ CHCOO (CH ₂ ) ₂ (CF)) _{2) 8} F) and co-oligomer of butyl acrylate, fluorine content: about 30 wt%, weight-average molecular weight: about 3000) 0.1 g.

<Examples 1 to 7>
Examples 1 to 4 are Examples and Examples 5 to 7 are Comparative Examples.
A light transmissive substrate 1 was manufactured by using an optical imprinting method, and a metal layer 2 was formed by using an oblique evaporation method, thereby manufacturing a wire grid polarizer.

Specifically, a light-transmitting substrate having the configuration shown in FIGS. 1A, 1B, and 2 was manufactured using the method illustrated in FIGS. 5A and 5B.
As the substrate 21, a cyclic polyolefin film having a thickness of 100 μm (Zeonor film, 100 mm × 100 mm, manufactured by Zeon Corporation) was used.
The photocurable composition 22 obtained in Preparation Example 1 was applied to the surface of the substrate 21 by spin coating to form a coating film having a thickness of 5 μm.
A quartz mold 23 having a concave portion having a shape corresponding to the ridge to be obtained is pressed at 25 ° C. by 0.5 MPa (gauge pressure) so that the entire surface of the concave portion is in contact with the photocurable composition 22. It was pressed against the coating of the photocurable composition 22 with pressure.
While maintaining this state, light from a high-pressure mercury lamp (frequency: 1.5 kHz to 2.0 kHz, main wavelength light: irradiation energy at 255 nm, 315 nm, 365 nm, 365 nm: 1000 mJ) is irradiated from the substrate 21 side for 15 seconds. After the photo-curable composition 22 was cured, the quartz mold was slowly separated to form the light-transmissive substrate 1 on the substrate 21.

Aluminum was vapor-deposited on the entire surface of the first side surface 11b1 of the ridge 11 of the light-transmitting substrate 1 and its vicinity using a vacuum vapor deposition device (SEC-16CM, manufactured by Showa Vacuum Co., Ltd.) to form the metal layer 2. The vapor deposition source and the light transmitting substrate 1 were relatively moved so that the vapor deposition angles (θ1, θ2) continuously increased.
The height Hg of the ridges 11 of the light-transmitting substrate 1, the range of the deposition angle, and the deposition amount (reference deposition angle and deposition film thickness) are changed as shown in Table 1, and the shape of the metal layer 2 is different. A wire grid polarizer was manufactured. The deposition amount was set so that when a film was formed at a reference deposition angle on a test piece fixed so that the deposition surface was perpendicular to the Y direction, the reference deposition film thickness was obtained. The pitch p of the ridge 11 was constant at 90 nm. After the vapor deposition, as shown in the example of FIG. 11, the entire first side surface 11b1 was covered with the metal layer 2, and the second side surface 11b2 had an exposed surface that was not covered with the metal layer 2.

Further, a resin layer 32 was provided. Table 1 shows the refractive index (n) of the resin layer 32 of each example at a wavelength of 589.3 nm.
With respect to the wire grid polarizer obtained in each example, Hg, Wh, Wm, and Wb were measured by the above-described method, and values of respective items shown in Table 1 were obtained. Rs / Rp was measured by the above method to obtain a graph shown in FIG. Based on the obtained graph, the areas S1 and S2 were obtained by the above method. Table 1 shows the results.

さ れ る As shown in the results in Table 1, Examples 1 to 4 had larger areas S1 and S2 at wavelengths of 450 to 650 and higher Rs / Rp ratios in the visible light region than Examples 5 to 7.

例 The following Examples 8 to 25 are reference examples in which performance was simulated based on the design values of the wire grid polarizer.

The performance of each of the wire grid polarizers was simulated by rigorous coupled-wave analysis (RCWA).
The wavelength of the incident light is 400 to 1000 nm, the incident direction is the Y direction, and the reflectance of p-polarized light (hereinafter also referred to as “Rp”) and the reflectance of s-polarized light (hereinafter also referred to as “Rs”) are calculated. I asked.
The material of the metal layer was aluminum, and the thickness e of the metal layer 2 was 30 nm. In the above calculation, the following measured values were used for the refractive index and the extinction coefficient of the metal layer. A photocurable resin was applied on a film substrate. Aluminum was obliquely vapor-deposited at 40 ° on the photocurable resin to form a flat film having a thickness of 30 nm. The flat film was measured and analyzed with an ellipsometer to determine the refractive index and the extinction coefficient.

<Examples 8 to 10>
In this example, a simulation was performed by changing the shape of the ridge in a wire grid type polarizer having a resin layer and having an embedding degree of 0% as shown in FIG. However, the refractive index adjusting layer 41 is not provided (the same applies hereinafter).
The cross-sectional shape of the ridge was Example 8 a triangle shown in FIG. 8, Example 9 a trapezoid shown in FIG. 10 (the width w of the flat surface at the top in the X direction was 10 nm), and Example 10 a rectangle shown in FIG. Tables 2 and 3 show the design values. Table 2 shows common design values in the following examples. FIG. 14 shows the result of Rp, and FIG. 15 shows the result of Rs.
As shown in these results, when the cross-sectional shape of the ridge is triangular or trapezoidal, Rp can be reduced in the entire wavelength range of 400 to 1000 nm as compared with the case of rectangular. The effect of the cross-sectional shape on the wavelength dependence of Rs is small. Therefore, when the cross-sectional shape of the ridge is triangular or trapezoidal, Rp can be reduced while maintaining Rs high, and as a result, the ratio of Rs / Rp can be increased.

<Examples 11 to 15>
In this example, simulation was performed by changing the degree of embedding of the resin layer (f / (c + d) × 100, unit%) in a wire grid polarizer having a resin layer as shown in FIGS. Tables 2 and 3 show the design values. In Examples 11 to 15, a '/ e is 1.21 and Qm / Qs is 0.35. FIG. 16 shows the result of Rp, and FIG. 17 shows the result of Rs.
As shown in these results, the wavelength dependence of Rp can be adjusted by the degree of embedding. The influence of the degree of embedding on the wavelength dependence of Rs is small. Rs tends to increase as the degree of embedding approaches zero in all wavelength ranges.
In particular, when the degree of embedding is around 0% or around 100%, Rp is kept low over the entire wavelength range of 400 to 1000 nm. When the embedding degree is 25 to 75%, Rp becomes lower as the wavelength becomes longer, and the Rp reduction effect is particularly excellent on the long wavelength side of 700 nm or more.

<Examples 16 to 20>
In this example, a simulation was performed by changing the refractive index (n) of the resin layer in a wire grid polarizer having a resin layer and having a burying degree of 0% as shown in FIG. Tables 2 and 3 show the design values. FIG. 18 shows the result of Rp, and FIG. 19 shows the result of Rs.
As shown in these results, the closer the refractive index (n) of the resin layer is to 1, the lower the Rp in the wavelength range of 550 to 750 nm. The influence of the refractive index of the resin layer on the wavelength dependence of Rs is small. Rs tends to be higher as the refractive index (n) is closer to 1 in the entire wavelength range.

<Examples 21 to 25>
In this example, a simulation was performed by changing the pitch b of the ridges in a wire grid polarizer having a resin layer and having an embedding degree of 0% as shown in FIG. The value of a was also changed so that a / b became 0.45. Tables 2 and 3 show the design values. FIG. 20 shows the result of Rp, and FIG. 21 shows the result of Rs.
As shown in these results, in a short wavelength region near 400 nm, the smaller the pitch, the lower the Rp, and in the wavelength region of 500 nm or more, the wider the pitch, the lower the Rp. The influence of pitch on the wavelength dependence of Rs is small. Rs tends to be higher as the pitch is smaller in the entire wavelength range.

<Production Example 1: Production of wire grid type polarizer>
After producing the light-transmitting substrate 1 on the substrate 21 in the same procedure as in Example 1, a metal layer was formed by the following method to obtain a wire grid polarizer having the substrate 21 on the back surface.
Using a vacuum evaporation apparatus (SEC-16CM, manufactured by Showa Vacuum Co., Ltd.) capable of changing the inclination of the light transmitting substrate 1 facing the evaporation source, aluminum is evaporated on the ridges of the light transmitting substrate 1 by oblique evaporation. Then, a metal layer was formed. The deposition angle θ was 27 °.
FIG. 22 shows a scanning electron microscope image of a cross section of the light transmitting substrate 1 before the metal layer is deposited.
FIG. 23 shows a scanning electron microscope image of a cross section of the obtained wire grid polarizer.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application (No. 2018-186780) filed on Oct. 1, 2018, the entire contents of which are incorporated by reference.

ワ イ ヤ A wire grid polarizer having a high Rs / Rp can be applied to an image display device provided with an optical system using s-polarized light included in reflected light.

Reference Signs List 1 light-transmitting substrate 2 metal layer 10 ridge (before etching)
DESCRIPTION OF SYMBOLS 11 Ridge 11a Top 11b1 1st side 11b2 2nd side 11c Lower end of a ridge 12 Concave groove 12a Bottom 21 Substrate 22 Photocurable composition 23, 24 Mold 31, 32, 33 Resin layer 31a, 33a Lower end 41 Refractive index adjusting layer 42 Anti-reflective substrate

Claims (10)

1. On the surface, a light-transmitting substrate in which mutually parallel ridges are formed at a predetermined pitch, and a metal layer made of a metal or a metal compound, provided on the surface of the light-transmitting substrate,
   The cross-sectional shape of the ridge, which is perpendicular to the length direction, has a width gradually reduced toward the top, and at least the first side of the first side and the second side sandwiching the top of the ridge. Is covered with the metal layer, and there is an exposed surface not covered with the metal layer on the second side surface,
   In a cross section orthogonal to the length direction of the ridge,
   The height from the bottom to the top of the ridge is 80 to 125 nm;
   The minimum value of the thickness in the width direction of the ridge of the metal layer covering the first side surface is Wm,
   The maximum value of the thickness in the width direction of the ridge of the metal layer covering the first side surface on the bottom side from the position of 1/2 of the height from the bottom to the top of the ridge is Wb;
   When the maximum value of the thickness in the width direction of the ridge of the metal layer present on the side opposite to the bottom side from the top of the ridge is Wh,
   A wire grid polarizer, wherein a ratio of the Wh to the Wm is 2.2 to 3.0 and a ratio of the Wb to the Wm is 1.5 to 2.1.
2. The wire grid polarizer according to claim 1, wherein the ratio of the Wh to the Wb is 1.4 or less.
3. The wire grid polarizer according to claim 1 or 2, further comprising a resin layer that covers the light transmitting substrate and the metal layer.
4. The wire grid polarizer according to claim 3, wherein the height Hg from the bottom to the top of the ridge and the refractive index n of the resin layer at a wavelength of 589.3 nm satisfy the following expression 1.
   450 ≦ 4 × n × Hg ≦ 650 Equation 1
5. In a graph obtained by the following measurement method, in which the x-axis is wavelength and the y-axis is Rs / Rp, it is surrounded by four straight lines represented by x = 450 nm, x = 451 nm, y = 0 and y = 1. The relative area S1 of a region surrounded by four lines represented by x = 450 nm, x = 650 nm, y = 0 and y = Rs / Rp, where the area of the rectangle is 1, is 7000 or more. 5. The wire grid polarizer according to 3 or 4.
   Measuring method: A wire grid type polarizer is sandwiched between two antireflection substrates having a reflectance of 0.7% or less at a wavelength of 450 to 650 nm, an incident angle of 5 °, a measuring wavelength of 450 to 650 nm, and a wavelength interval of 1 nm. Under the conditions, the s-polarized light reflectance and the p-polarized light reflectance are measured, respectively, and Rs / Rp, which is the ratio of the s-polarized light reflectance to the p-polarized light reflectance, is determined. The x-axis is wavelength, and the y-axis is Rs / Rp. Create
6. On the surface, a light-transmitting substrate in which mutually parallel ridges are formed at a predetermined pitch, and a metal layer made of a metal or a metal compound, provided on the surface of the light-transmitting substrate,
   The cross-sectional shape of the ridge, which is perpendicular to the length direction, has a width gradually reduced toward the top, and at least the first side of the first side and the second side sandwiching the top of the ridge. Is covered with the metal layer, and there is an exposed surface not covered with the metal layer on the second side surface,
   Having a resin layer covering the light transmitting substrate and the metal layer,
   In a graph obtained by the following measurement method, in which the x-axis is wavelength and the y-axis is Rs / Rp, it is surrounded by four straight lines represented by x = 450 nm, x = 451 nm, y = 0 and y = 1. Assuming that the area of the rectangle is 1, a wire grid in which the relative area S1 of a region surrounded by four lines represented by x = 450 nm, x = 650 nm, y = 0, and y = Rs / Rp is 7000 or more Type polarizer.
   Measuring method: A wire grid type polarizer is sandwiched between two antireflection substrates having a reflectance of 0.7% or less at a wavelength of 450 to 650 nm, an incident angle of 5 °, a measuring wavelength of 450 to 650 nm, and a wavelength interval of 1 nm. Under the conditions, the s-polarized light reflectance and the p-polarized light reflectance are measured, respectively, and Rs / Rp, which is the ratio of the s-polarized light reflectance to the p-polarized light reflectance, is determined. The x-axis is wavelength, and the y-axis is Rs / Rp. Create
7. Having a first support on the back surface of the light-transmitting substrate, and having a second support via an adhesive on a surface of the resin layer opposite to the light-transmitting substrate side, The wire grid polarizer according to any one of claims 3 to 6.
8. The light-transmitting substrate according to claim 3, further comprising a first support on a back surface of the light-transmitting substrate, and a refractive index adjustment layer on a surface of the resin layer opposite to the light-transmitting substrate. The wire grid polarizer according to claim 1.
9. A polarizing plate comprising the wire grid polarizer according to any one of claims 1 to 8.
10. An image display device including the wire grid polarizer according to any one of claims 1 to 8.

Images