Antireflection member and manufacturing method

Abstract

This antireflection member has an antireflection layer. The antireflection layer is positioned on the outermost surface of the antireflection member to constitute an antireflection surface. The antireflection layer has an uneven structure comprising a base layer and a large number of protrusions provided on the base layer. w2, h, nb, np, Vp, Vv, and nv satisfy predetermined requirements. w2 is a minor axis of the bottom surface of the protrusion, h is the height of the protrusion, nb is the refractive index of the material constituting the base layer, np is the refractive index of the material constituting the protrusion, Vp and Vv are the volume occupied by the protrusion and the volume occupied by the gap between the protrusions in the region from the top part to the depth h of the protrusion, respectively, and nv is the refractive index of the substance constituting the gap.

Description

Anti-reflection member and manufacturing method

[0001] The present invention relates to an antireflection member and a method for manufacturing the same.

[0002] Optical devices are sometimes required to effectively suppress undesired light reflections on their surfaces. Taking a display device such as a liquid crystal display device as an example of an optical device, when light is incident on the display surface of the display device, the light is reflected from the display surface, and the reflected light may be observed by a viewer. Such reflected light may be perceived as a mirror image of an object outside the device. Furthermore, the presence of reflected light may reduce the apparent brightness of the display, resulting in a loss of display quality. Therefore, it is required to suppress such reflections and improve the display quality of the display device.

[0003] In order to suppress such reflection, it has been conventional to provide an anti-reflection member on the surface of an optical device. For example, it is known to provide a film-like anti-reflection member on the display surface of a display device.

[0004] An example of an antireflection member is an antireflection member equipped with an interference film. However, when suppressing reflection using an interference film, it is very difficult to adjust the refractive index of each layer constituting the interference film to a value that generates ideal interference, and therefore it is difficult to obtain low reflectance over a wide wavelength range.

[0005] Another example of an antireflection member is an antireflection member that utilizes a structural refractive index developed by a microstructure on the surface, such as a moth-eye structure. However, antireflection members having a microstructure on the surface have poor antifouling properties. Specifically, the microstructure for achieving such structural refraction has a long, narrow convex structure protruding from the antireflection surface, so dirt easily adheres to the surface, making it difficult to sufficiently remove the adhered dirt, and the adhered dirt significantly reduces the reflectance. Antireflection members having a microstructure on the surface can also suppress the reflectance to about 0.5% over a wide wavelength range, but further reduction in reflectance is required.

[0006] Another known example of an antireflection member that exhibits antireflection properties through a microstructure on its surface is the technology described in Patent Document 1. This document discloses that a reflectance of 1% or less to 2% or less is achieved by transferring the structure of a mold onto a material such as polycarbonate to form V-shaped grooves with a period in the range of 35 nm to 400 nm.

[0007] Japanese Patent Application Laid-Open No. 2003-043203

[0008] The above-mentioned prior art has not provided an antireflection member that combines the advantages of low reflectance over a wide wavelength range, high antifouling properties, and ease of production.

[0009] Therefore, an object of the present invention is to provide an antireflection member having advantages such as low reflectance over a wide wavelength range, high antifouling properties, and ease of production, and a method for producing the same.

[0010] As a result of investigations aimed at solving the above-mentioned problems, the present inventors came up with the idea of ​​forming a large number of convex portions that satisfy specific requirements on the surface of an antireflection layer, and utilizing the low refractive index that occurs in the depth region where the convex portions are provided, to construct an antireflection member, thereby solving the above-mentioned problems, and completed the present invention. That is, the present invention is as follows.

[0011] (1) An antireflection member including an antireflection layer, wherein the antireflection layer is located on the outermost surface of the antireflection member and constitutes an antireflection surface, the antireflection layer has a base layer and an uneven structure consisting of a large number of convex portions provided on the base layer, and satisfies the following formulas (e1) to (e4): w ２ / h>1 (e1) 0.9≦n ｅｆｆ / (n ｂ ) １／２ ≦1.1 (e2) 0.6≦(h・n ｅｆｆ ) / 137.5≦1.5 (e3) w ２ <400 (e4) However, w ２ is the minor axis (nm) of the bottom surface of the convex portion, h is the height (nm) of the convex portion, and n ｅｆｆ is a value represented by the following formula (e5), ｅｆｆ = nｐ × (V ｐ / (V ｐ +V ｖ )) + n ｖ × (V ｖ / (V ｐ +V ｖ )) Formula (e5) n ｂ is the refractive index of the material constituting the base layer, and n ｐ is the refractive index of the material constituting the convex portion, and V ｐ and V ｖ are the volume occupied by the convex portions and the volume occupied by the gaps between the convex portions in the region from the top of the convex portions to a depth h, respectively, and n ｖ is the refractive index of a material that constitutes the voids. (2) An antireflection member according to (1), having a front reflectance of 1.5% or less over the entire wavelength range of 400 to 700 nm. (3) A method for producing an antireflection member according to (1) or (2), comprising: Step 1: applying a coating liquid for forming a resin layer onto a substrate to form a coating liquid layer; and Step 2: transferring a concave-convex shape to the coating liquid layer, irradiating it with energy rays to cure it, and forming an antireflection layer.

[0012] The antireflection member of the present invention has the advantages of low reflectance over a wide wavelength range, high antifouling properties, and ease of production. The production method of the present invention also makes it possible to easily produce the antireflection member of the present invention.

[0013] FIG. 1 is a perspective view schematically showing an example of an antireflection member of the present invention. FIG. 2 is a partial longitudinal cross-sectional view of a convex portion 120 in FIG. 1 cut along line L1. FIG. 3 is a perspective view schematically showing another example of an antireflection member of the present invention. FIG. 4 is a partial longitudinal cross-sectional view of a convex portion 320 in FIG. 3 cut along line L3. FIG. 5 is a graph showing simulation results of an example and a comparative example. FIG. 6 is a graph showing simulation results of an example and a comparative example. FIG. 7 is a graph showing simulation results of an example and a comparative example. FIG. 8 is a side view schematically showing an example of a manufacturing apparatus for carrying out the manufacturing method of the present invention and a manufacturing method using the same. FIG. 9 is a longitudinal cross-sectional view showing a more specific example of an antireflection member obtained by the manufacturing method of the present invention. FIG. 10 is a longitudinal cross-sectional view showing another more specific example of an antireflection member obtained by the manufacturing method of the present invention.

[0014] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0015] In the present application, a "long" film refers to a film having a length that is 5 times or more its width, preferably 10 times or more its width, and specifically refers to a film having a length that can be wound into a roll for storage or transportation. There is no particular upper limit to the length of a long film, and it can be, for example, 100,000 times or less its width.

[0016] In this application, the refractive index is a relative refractive index, with the refractive index of air being taken as 1.0. Unless otherwise specified, the refractive index is a value measured using light with a wavelength of 550 nm.

[0017] In the following descriptions of Figures 1 to 4 and 9 to 10, unless otherwise specified, the antireflection member will be described as being placed horizontally with the antireflection surface (i.e., the surface facing the viewer and exhibiting the function of preventing reflection toward the viewer) facing upward. Therefore, the side of the antireflection member that is viewed by the viewer may simply be referred to as the "upper" side, and the opposite side as the "lower" side. For example, of one surface and the other surface of a certain layer, the surface closer to the side viewed by the viewer may be referred to as the "upper" surface. Furthermore, the direction perpendicular to these "upper" and "lower" directions may be referred to as the "horizontal" direction.

[0018] [1. Overview of Antireflection Member] The antireflection member of the present invention includes an antireflection layer. The antireflection layer is located on the outermost surface of the antireflection member and constitutes an antireflection surface. However, components other than the antireflection layer are optional, and the antireflection member may consist only of the antireflection layer.

[0019] The anti-reflection layer has a concave-convex structure consisting of a base layer and a number of convex portions provided on the base layer. The base layer and the convex portions may be made of different materials, or may be integrally molded from the same material. The base layer and the convex portions are made of a light-transmitting material such as an optical resin.

[0020] Fig. 1 is a perspective view schematically showing an example of an antireflection member of the present invention, and Fig. 2 is a partial longitudinal cross-sectional view of a convex portion 120 in Fig. 1 taken along a longitudinal cross section line L1. In the example of Figs. 1 and 2, the antireflection member is composed of only an antireflection layer 10.

[0021] The anti-reflection layer 10 includes a base layer 110, which is a substantially flat member, and a large number of protrusions 120 provided on the upper surface, which is the anti-reflection side of the base layer 110. In this example, the base layer 110 and the protrusions 120 of the anti-reflection layer 10 are integrally formed from the same material.

[0022] 1 and 2 and other figures are schematic diagrams, and therefore show a state in which a small number of large protrusions are provided on a base layer, but an actual antireflection member usually has a much larger number of protrusions that are much smaller relative to the dimensions of the base layer than in this example. In this example, the macroscopic structure of the antireflection member (the structure observed while ignoring the fine uneven structure) is a flat and flexible film.

[0023] 1 and 2, the numerous protrusions 120 are periodically arranged at regular intervals on the antireflection surface. Specifically, on the antireflection surface of the antireflection layer 10, the protrusions 120 are periodically arranged in the direction of arrow p120x at a pitch that is the length of arrow p120x, and are also periodically arranged in the direction of arrow p120y that is perpendicular to arrow p120x at a pitch that is the length of arrow p120y.

[0024] Each of the protrusions 120 is molded integrally with the base layer 110 and therefore has no physical boundary with the base layer 110, but due to its structure, it has a square bottom surface 122 that is defined as a flat area protruding from the flat base layer 110. The protrusions 120 also have a flat top surface 121. The top surface 121 has a shape that is smaller than the bottom surface 122 and is fitted inside the bottom surface 122 when observed from above, and therefore the side surfaces 123 that make up the protrusions 120 have a tapered shape. The tapered shape of the protrusions makes it easy to form the protrusions using a mold.

[0025] (Requirements for Antireflection Layer) The antireflection layer satisfies the following formulas (e1) to (e4): w ２ / h>1 (e1) 0.9≦n ｅｆｆ / (n ｂ ) １／２ ≦1.1 (e2) 0.6≦(h・n ｅｆｆ ) / 137.5≦1.5 (e3) w ２ <400 (e4)

[0026] w ２In the example shown in FIGS. 1 and 2, the bottom surface 122 has a square shape, so the length of one side (the length indicated by the arrow w122 in FIGS. 1 and 2) is w ２ On the other hand, the minor axis w of the top surface 121 of the convex portion １ is the length indicated by the arrow w121 in Figure 2. In the present invention, it is not essential that the convex portion has a flat surface at its top. However, if it has such a flat top surface, its minor diameter w １ is the minor axis of the base w ２ It is preferable that the length is shorter from the viewpoint of ease of molding and stain resistance. １ / w ２ The value of w is preferably less than 1, more preferably 0.9 or less. １ / w ２ The lower limit of the value is not particularly limited, but can be, for example, 0.4 or more.

[0027] h is the height (nm) of the convex portion. That is, h is the height from the level of the base layer to the top of the convex portion. In the example shown in FIGS. 1 and 2, the height indicated by the arrow h120 corresponds to h.

[0028] As shown in formula (e1), w ２ / h is greater than 1. ２ / h is preferably 1.3 or more, more preferably 1.5 or more. ２ When w / h is a value equal to or greater than the lower limit, an antireflection member that is easy to mold and has high antifouling properties can be formed while exhibiting the optical effect based on the uneven structure. ２ The upper limit of / h is not particularly limited, but it is necessary to select w ２ Since it is necessary to be smaller than a certain degree, it is usually 2.3 or less.

[0029] As shown in equation (e4), w ２ is less than 400 nm. ２ Preferred ranges of values ​​for h and, if present, w １ The values ​​of each of the above can be adjusted appropriately to obtain the desired effect. ２is preferably 160 nm or more, more preferably 190 nm or more, and is less than 400 nm, preferably 320 nm or less, more preferably 260 nm or less. h is preferably 95 nm or more, more preferably 105 or more, and is preferably 155 nm or less, more preferably 130 or less.

[0030] w １ , w ２ When different dimensions exist for each of h and σ in one antireflection layer, their arithmetic mean values ​​can be used.

[0031] Regarding formula (e2), n ｅｆｆ is a value expressed by the following formula (e5): ｅｆｆ = n ｐ × (V ｐ / (V ｐ +V ｖ )) + n ｖ × (V ｖ / (V ｐ +V ｖ )) Formula (e5)

[0032] n ｂ is the refractive index of the material that makes up the base layer, and n ｐ is the refractive index of the material that makes up the convex portion. When the base layer and the convex portion are made of the same material, n ｂ and ｐ is the same value as

[0033] n ｂ and n ｐ can be appropriately adjusted by selecting the materials constituting it. ｂ and n ｐ However, even when the refractive index is in the range of 1.45 to 1.65, which is the refractive index of ordinary transparent optical members, a good anti-reflection function can be obtained.

[0034] V ｐ and V ｖ are the volume occupied by the convex portions in the region from the top of the convex portion to a depth h, and the volume occupied by the voids between the convex portions, respectively. Hereinafter, this layered region from the top of the convex portion to a depth h may be simply referred to as the "convex portion region layer."

[0035] n ｖ is the refractive index of the material that makes up the gap in the environment in which the anti-reflection member is used. Normally, no material is provided in the gap and air is present, so n ｖ is the refractive index of air, that is, 1.0.

[0036] V ｐ / (V ｐ +V ｖ ) and V ｖ / (V ｐ +V ｖ The value of V can be adjusted to a desired range by adjusting the shape of the convex portions and also by adjusting the density of the convex portions provided on the antireflection surface. In particular, when the convex portions 120 are periodically arranged on the antireflection surface as in the example shown in FIGS. 1 and 2, the pitch of the period (the lengths of p120x and p120y in the example shown in FIGS. 1 and 2) can be adjusted to adjust V ｐ / (V ｐ +V ｖ ) and V ｖ / (V ｐ +V ｖ ) can be easily adjusted.

[0037] As shown in formula (e2), n ｅｆｆ / (n ｂ ) １／２ is a value close to 1. ｅｆｆ / (n ｂ ) １／２ is 0.9 or more, preferably 0.95 or more, and more preferably 0.98 or more. ｅｆｆ / (n ｂ ) １／２ is 1.1 or less, preferably 1.05 or less, and more preferably 1.02 or less. ｅｆｆ / (n ｂ ) １／２When the reflectance of the antireflection layer is within the above range and other requirements of the antireflection layer are satisfied, a low reflectance can be easily achieved over a wide wavelength range. The front reflectance of the antireflection member can be measured by attaching a light-absorbing material such as black vinyl tape to the surface of the antireflection member opposite the antireflection layer, and then measuring the front reflectance of the antireflection layer side using a general spectrophotometer (for example, product name "V750" manufactured by JASCO Corporation).

[0038] Furthermore, as shown in equation (e3), (h n ｅｆｆ ) / 137.5 is also a value close to 1. ｅｆｆ ) / 137.5 is 0.6 or more, preferably 0.85 or more, and more preferably 0.95 or more. ｅｆｆ ) / 137.5 is 1.5 or less, preferably 1.3 or less, and more preferably 1.15 or less. ｅｆｆ When the value of 1 / 137.5 is within the above range and other requirements of the antireflection layer are satisfied, a low reflectance in a wide wavelength range can be easily achieved.

[0039] When the antireflection layer satisfies the formula (e4), that is, when the shape of the convex portions is smaller than a certain degree, the convex portion region is a region in which the convex portions and voids are minutely intertwined, and the refractive index optically manifested there is n ｅｆｆ In such a case, if the antireflection layer also satisfies formula (e2) and formula (e3), interference occurs between the reflected light reflected by the base layer and the reflected light reflected by the convex region due to the difference in refractive index between the base layer and the convex region, thereby attenuating the reflected light and achieving an antireflection effect. The inventors have discovered that by constructing an antireflection layer that satisfies these requirements, the antireflection member of the present invention can have a front reflectance that is low, preferably 1.5% or less, more preferably 1.0% or less, and even more preferably 0.8% or less, over the entire wavelength range of 400 to 700 nm. In a particularly preferred embodiment, an antireflection layer can be easily obtained that can reduce the reflectance at 550 nm to zero% and suppress the reflectance to a low value of 0.5% or less over a wide wavelength range. Moreover, in the present invention, ２ / h>1 while still achieving such a low reflectance. As a result, compared to conventional antireflection members that utilize structural refraction, such as those that utilize a moth-eye structure, the antireflection member has the advantage of being highly stain-resistant while also being able to exhibit a high antireflection effect.

[0040] (Modifications) The antireflection member of the present invention is not limited to the specific example described above and may be modified. For example, in the example shown in Figures 1 and 2, the bottom surface 122 of the convex portion 120 is square, but the shape of the bottom surface of the convex portion in the antireflection member of the present invention is not limited to this and may be other shapes. Such modifications of the bottom surface shape will be described with reference to Figures 3 and 4.

[0041] Fig. 3 is a perspective view schematically showing another example of the antireflection member of the present invention, and Fig. 4 is a partial longitudinal cross-sectional view of the protrusion 320 in Fig. 3 taken along line L3. In the example of Figs. 3 and 4, the antireflection member consists of only the antireflection layer 30.

[0042] The anti-reflection layer 30 includes a base layer 310, which is a substantially flat member, and a large number of protrusions 320 provided on the upper surface, which is the anti-reflection side of the base layer 310. In this example, the base layer 310 and the protrusions 320 of the anti-reflection layer 30 are integrally formed from the same material.

[0043] 3 and 4, a large number of protrusions 320 are periodically arranged at regular intervals on the antireflection surface. Specifically, on the antireflection surface of the antireflection layer 30, the protrusions 320 are periodically arranged in the direction of arrow p320x at a pitch equal to the length of arrow p320x, and are periodically arranged in the direction of arrow p320y at a pitch equal to the length of arrow p320y, and are periodically arranged in the direction of arrow p320z at a pitch equal to the length of arrow p320z. The directions of arrows p320x to p320z form an angle of 60° with each other.

[0044] Like the protrusion 120, the protrusion 320 also has a bottom surface 322 defined as a flat area protruding from the flat base layer 310. However, unlike the protrusion 120, the bottom shape of the protrusion 320 is circular. Therefore, the diameter (the length indicated by the arrow w322 in Figures 3 and 4) is w ２ is equivalent to

[0045] The convex portion 320 further has a flat top surface 321. The top surface 321 is smaller than the bottom surface 322, and when observed from above, is shaped to fit inside the bottom surface 322, so that the side surfaces 323 that make up the convex portion 320 have a tapered shape. The tapered shape of the convex portion makes it easy to form the convex portion using a mold. The minor axis w of the top surface 321 of the convex portion １ is the length indicated by the arrow w321 in Fig. 4. In this example, the height indicated by the arrow h320 corresponds to h.

[0046] Even in the case of such an antireflection layer having a large number of convex portions each having a circular bottom surface, the effects of the present invention can be obtained by satisfying the requirements of formulas (e1) to (e4), as in the example of FIGS. 1 and 2 .

[0047] In the examples of FIGS. 1 and 2 and the examples of FIGS. 3 and 4, the convex portions (120 or 320) all have the same shape and are periodically arranged at a certain pitch, but the present invention is not limited to this, and the convex portions may be arranged randomly. Furthermore, the convex portions may not all have the same shape, and there may be a variation in shape. Even when such convex portions are present, the effects of the present invention can be obtained by satisfying the requirements of formulas (e1) to (e4), as in the examples of FIGS. 1 and 2 and the examples of FIGS. 3 and 4.

[0048] In the examples of Figures 1 and 2 and the examples of Figures 3 and 4, the convex portion and the base layer are integrally formed from the same material, but the present invention is not limited to this, and the convex portion and the base layer may be formed from different materials.

[0049] 1 and 2 and 3 and 4, the antireflection member is composed of only an antireflection layer, and its macroscopic structure is a flat and flexible film, but the present invention is not limited to this, and a layer other than the antireflection layer may be provided as a base for the antireflection layer. Furthermore, the macroscopic structure of the antireflection member is not limited to the structure of a film, and may be the structure of an optical member other than a film, such as a lens.

[0050] (Manufacturing Method) The antireflection member of the present invention can be manufactured by various known manufacturing methods. A preferred manufacturing method includes the following steps. This manufacturing method will be described below as the manufacturing method of the present invention.

[0051] Step 1: A coating liquid for forming a resin layer is applied onto a substrate to form a coating liquid layer. Step 2: A concave-convex shape is transferred onto the coating liquid layer, and the coating liquid layer is cured by irradiating it with energy rays to form an anti-reflection layer.

[0052] 8 is a side view schematically showing an example of a manufacturing apparatus for carrying out the manufacturing method of the present invention and a manufacturing method using the same. In Fig. 8, manufacturing apparatus 80 includes, in order from upstream of the transport path, a payout roll 801, a coating device 821, a master roll 802, a light source 822, and a take-up roll 803. Manufacturing apparatus 80 further includes touch rolls 808 and 809 provided adjacent to master roll 802.

[0053] In operation of the manufacturing apparatus 80, the delivery roll 801 rotates in the direction of arrow AR1, and supplies the long substrate 811 to the delivery transport path in the direction of arrow A1.

[0054] Downstream of the delivery roll 801, a coating device 821 is used to apply a coating liquid to a substrate 821, thereby forming a multi-layered product 812 including a substrate 811 and a coating liquid layer. In this example, ultraviolet rays are used as the energy rays for curing, and therefore an ultraviolet-curable liquid for forming a hard coat layer is used as the coating liquid.

[0055] Next, the multi-layered product 812 is transported along a transport path and wrapped around the master roll 802, which rotates in the direction of arrow AR2, with the coating liquid layer facing inward. The master roll 802 has a fine uneven structure on its peripheral surface. By pressing the touch rolls 808 and 809 against the multi-layered product 812 while biasing them toward the center of the master roll 802, the uneven structure can be transferred to the coating liquid layer of the multi-layered product 812.

[0056] Furthermore, along the transport path on the peripheral surface of the master roll 802 being pressed against the master roll 802, light is irradiated from a light source 822 onto the multilayer structure 812 pressed against the master roll 802, thereby curing the coating liquid layer. The energy ray can be selected appropriately from energy rays that have the property of curing the coating liquid, such as visible light, ultraviolet light, or infrared light. In this example, ultraviolet light is used as the energy ray. In this case, the energy ray is irradiated from the substrate side. However, by using a material for the substrate that transmits energy rays, the energy ray can reach the coating liquid layer and achieve curing. This operation hardens the coating liquid layer in a state in which the concavo-convex structure is transferred, resulting in an antireflection member 813 including the substrate 811 and the antireflection layer provided thereon. The antireflection member 813 is further transported, rotates in the direction of arrow AR3, and is taken up by a take-up roll 803 that takes up the antireflection member 813.

[0057] FIG. 9 is a longitudinal cross-sectional view showing a more specific example of an antireflection member obtained by the manufacturing method of the present invention, and FIG. 10 is a longitudinal cross-sectional view showing another more specific example of an antireflection member obtained by the manufacturing method of the present invention.

[0058] 9 includes a substrate 811 and a hard coat layer 819A formed continuously on the substrate surface. Convex portions 820A of the uneven structure are formed as part of the hard coat layer 819A, and a base layer 810A formed as part of the hard coat layer 819A is present below the convex portions. Therefore, in this example, the hard coat layer 819A including the convex portions 820A and the base layer 810A functions as an anti-reflection layer, and its refractive index n ｂ and n ｐis the refractive index of the hard coat layer 819A. An antireflection member in which the convex portions and the base layer are integrally formed has the advantage that the mechanical strength of the convex portions is high. Such an antireflection member can be easily formed by applying a relatively weak pressure to press the multilayer structure 812 against the master roll 802 in the above-described step 2.

[0059] On the other hand, the anti-reflection member 813B shown in Figure 10 comprises a substrate 811 and convex portions 819B of a hard coat layer discontinuously formed on the surface thereof. The substrate 811, which functions as a base layer, is present below the convex portions 819B. Therefore, in this example, the convex portions 819B of the hard coat layer and the base layer 811 of the substrate function as an anti-reflection layer, and their refractive index n ｂ and n ｐ are the refractive index of the substrate 811 and the refractive index of the hard coat layer 819B, respectively. An antireflection member in which such convex portions and the base layer are molded as separate members has advantages such as a high degree of freedom in designing optical properties and the ability to easily produce a thin member. Such an antireflection member can be easily molded by applying a relatively strong pressure to press the multilayer structure 812 against the master roll 802 in the above-mentioned step 2.

[0060] (Materials for Constituting the Antireflection Member) Materials for constituting the antireflection member can be appropriately selected from known materials for optical members so as to have the desired refractive index and other properties.

[0061] As in the above-described example, in the case of an anti-reflection member having a substrate and a hard coat layer, examples of materials constituting the hard coat layer include various active energy ray-curable resins. Examples of active energy ray-curable resins include organic silicone-based, melamine-based, epoxy-based, acrylic-based, urethane (meth)acrylate-based, and polyfunctional (meth)acrylate-based resins. Among these, urethane (meth)acrylate-based ultraviolet-curable resins and / or polyfunctional (meth)acrylate-based ultraviolet-curable resins are preferred from the viewpoint of good adhesive strength, excellent toughness, and productivity. These may be used alone, or two or more types may be used in any combination. More specific examples of these resins include those described in International Publication No. 2021 / 215317.

[0062] Examples of materials constituting the substrate include various resins used as materials for optical components. Specific examples of resins are preferably thermoplastic resins, and among them, alicyclic structure-containing resins are preferred. The alicyclic structure-containing resin is a resin containing an alicyclic structure-containing polymer, and is excellent in properties such as transparency, low moisture absorption, dimensional stability, and light weight, making it suitable as a material for optical components.

[0063] The alicyclic structure-containing polymer is a polymer having an alicyclic structure in the structural unit of the polymer, and either a polymer having an alicyclic structure in the main chain or a polymer having an alicyclic structure in the side chain may be used. The alicyclic structure-containing polymer may be used alone or in combination of two or more types in any ratio. Among them, from the viewpoint of mechanical strength, heat resistance, etc., a polymer having an alicyclic structure in the main chain is preferred.

[0064] Examples of polymers containing an alicyclic structure include (1) norbornene-based polymers, (2) monocyclic olefin polymers, (3) cyclic conjugated diene polymers, (4) vinyl alicyclic hydrocarbon polymers, and hydrogenated versions thereof. Among these, norbornene-based polymers and hydrogenated versions thereof are preferred from the viewpoints of transparency and moldability.

[0065] Examples of norbornene-based polymers include ring-opening polymers of monomers having a norbornene structure and their hydrogenated products; and addition polymers of monomers having a norbornene structure and their hydrogenated products. Examples of ring-opening polymers of monomers having a norbornene structure include ring-opening homopolymers of one type of monomer having a norbornene structure, ring-opening copolymers of two or more types of monomers having a norbornene structure, and ring-opening copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, addition copolymers of two or more types of monomers having a norbornene structure, and addition copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Examples of these polymers include the polymers disclosed in, for example, JP 2002-321302 A.

[0066] Specific examples of suitable norbornene polymers and hydrogenated products thereof include "ZEONOR" manufactured by Nippon Zeon Co., Ltd.; "ARTON" manufactured by JSR Corporation; and "TOPAS" manufactured by TOPAS ADVANCED POLYMERS.

[0067] (Uses of Antireflection Member) The antireflection member of the present invention can be used as a component of various optical devices that require suppression of light reflection on their surfaces. Examples of optical devices include display devices such as liquid crystal display devices and electroluminescence display devices, and the antireflection member of the present invention can be used as a component that prevents reflection on the display surfaces of these devices. The antireflection member of the present invention can also be used as an optical member such as a lens, or as a component thereof, to exhibit the function of preventing reflection on the surface of the optical member.

[0068] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples shown below, and can be practiced with any modifications within the scope of the claims of the present invention and their equivalents.

[0069] Example 1 The relationship between the wavelength of incident light on an anti-reflection member and the reflectance at that wavelength was determined by simulation. The anti-reflection member assumed in the simulation of this example is as follows: The anti-reflection member is made of a schematic anti-reflection layer 10 shown in Figures 1 and 2, and its base layer 110 and convex portion 120 are integrally formed from the same material. The refractive index n ｂ and n ｐ The gap between the protrusions 120 is filled with air, so n ｖ The minor axis w of the square base 122 of the convex portion 120 is 1.0. ２ The height h of the protrusion 120 (height h120 in FIG. 2) is 112 nm. The minor axis w of the square top surface 121 of the protrusion 120 is １ The length w121 in FIG. 2 is 195 nm. The intervals at which the convex portions 120 are provided (periods p120x and p120y in FIGS. 1 and 2) are adjusted, and as a result, n ｅｆｆ is 1.242. Therefore, n ｅｆｆ / (n ｂ ) １／２ is 1.004, (h·n ｅｆｆ ) / 137.5 is 1.021.

[0070] The reflectance of the antireflection surface of this antireflection member was calculated using the Rigorous Coupled Wave Analysis (RCWA) method when incident light was incident from the top surface of the antireflection member in a direction perpendicular to the antireflection surface. The calculation was performed assuming that no reflection of light transmitted below the base layer was observed. The results are shown in Figure 5 by the curve designated Ex1. In Figures 5 to 7, the horizontal axis represents the wavelength of the reflected light, and the vertical axis represents the reflectance when the reflectance when all incident light is reflected is set to 1.

[0071] Comparative Example 1 The relationship between the wavelength of incident light and the reflectance at that wavelength of an antireflection member commonly used in conventional technology was determined by simulation. The antireflection member assumed in the simulation of this comparative example is as follows: - The antireflection member has a structure in which a single flat low-refractive index layer is provided on the upper surface of a flat base layer. - The refractive index of the base layer is 1.53. - The refractive index of the low-refractive index layer is 1.38, and the thickness of the low-refractive index layer is 100 nm.

[0072] The reflectance of the antireflection surface of this antireflection member was calculated using the Rigorous Coupled Wave Analysis (RCWA) method when incident light was incident from a direction perpendicular to the antireflection surface of the antireflection member from the top surface side. The calculation was performed assuming that there was no reflection of light transmitted below the base layer. The results are shown in Figure 5 by the curve referenced CEx1.

[0073] (Comparative Example 2) The relationship between the wavelength of incident light and the reflectance at that wavelength of an antireflection member commonly used in conventional technology was determined by simulation. The antireflection member assumed in the simulation of this comparative example is as follows: - The antireflection member has a structure in which one flat intermediate layer is provided on the upper surface of a flat base layer, and one flat low refractive index layer is further provided on the upper surface of that. - The refractive index of the base layer is 1.53. - The refractive index of the intermediate layer is 1.65, and the thickness of the intermediate layer is 83 nm. - The refractive index of the low refractive index layer is 1.38, and the thickness of the low refractive index layer is 100 nm.

[0074] The reflectance of the antireflection surface of this antireflection member was calculated using the Rigorous Coupled Wave Analysis (RCWA) method when incident light was irradiated from the top surface of the antireflection member in a direction perpendicular to the antireflection surface. The calculation was performed assuming that there was no reflection of light transmitted below the base layer. The results are shown in Figure 5 by the curve referenced CEx2.

[0075] (Examples 2 to 8) Refractive index n of base layer and convex portion ｂ and n ｐ, the height h of the convex portion 120, and the minor axis w of the top surface 121 １ , the minor axis w of the bottom surface 122 ２ , and n ｅｆｆ / (n ｂ ) １／２ The same simulation as in Example 1 was performed, except that the value of was changed as shown in Table 1, to determine the relationship between the wavelength of incident light on the antireflection member and the reflectance at that wavelength. These results are shown in Figure 6, along with the results of Example 1, as curves referenced with the symbols Ex1 to Ex8. For comparison, the results of Comparative Examples 1 and 2 are also shown in Figure 6. The eight curves showing the results of the Examples in Figure 6 represent Examples 2 to 4, Example 1, and Examples 5 to 8, in order from the lowest reflectance value at the right end.

[0076]

[0077] Example 9 The relationship between the wavelength of incident light on an anti-reflection member and the reflectance at that wavelength was determined by simulation. The anti-reflection member assumed in the simulation of this example is as follows: The anti-reflection member is made of a schematic anti-reflection layer 30 shown in Figures 3 and 4, and its base layer 310 and protrusions 320 are integrally formed from the same material. The refractive index n ｂ and n ｐ The gap between the protrusions 320 is filled with air, so n ｖ The minor axis w of the square base 322 of the convex portion 320 is 1.0. ２ The height h of the protrusion 320 (height h320 in FIG. 2) is 110 nm. The minor axis w of the square top surface 321 of the protrusion 320 is １ The length w321 in FIG. 2 is 195 nm. The intervals at which the convex portions 320 are provided (periods p320x and p320y in FIGS. 1 and 2) are adjusted to ｅｆｆ is 1.22. Therefore, n ｅｆｆ / (n ｂ ) １／２ is 0.986, and (h n ｅｆｆ ) / 137.5 is 0.976.

[0078] The reflectance of the antireflection surface of this antireflection member was calculated using RCWA (Rigorous Coupled Wave Analysis) when incident light was incident from a direction perpendicular to the antireflection surface of the antireflection member from the top surface side. The calculation was performed assuming that there was no reflection of light transmitted below the base layer. The results are shown in Figure 7 by the curve referenced Ex3. For comparison, the results of Example 1, Comparative Example 1, and Comparative Example 2 are also shown in Figure 6.

[0079] 5 to 7 show that, according to the present invention, it is possible to easily construct an antireflection member that has a lower reflectance than conventional antireflection members and a wider wavelength range over which reflectance can be suppressed, using materials with a refractive index of 1.48 to 1.62, which is the range of refractive index typically found in materials that are conventionally known, relatively low cost, and have excellent mechanical properties. In addition, the antireflection members of Examples 1 to 9, due to their structure, can have a lower height relative to the width of the concave-convex structure than conventional antireflection members that utilize structural refraction, such as moth-eye films. Therefore, they are easy to manufacture and can ensure high antifouling properties.

[0080] REFERENCE SIGNS LIST 10 anti-reflection layer 30 anti-reflection layer 80 manufacturing apparatus 110 base layer 120 convex portion 121 top surface 122 bottom surface 123 side surface 310 base layer 320 convex portion 321 top surface 322 bottom surface 323 side surface 801 pay-out roll 802 master roll 803 take-up roll 808 touch roll 809 touch roll 810A base layer 811 substrate 812 composite 813 anti-reflection member 813A anti-reflection member 813B anti-reflection member 819A hard coat layer 819B convex portion of hard coat layer 820A convex portion 821 coating apparatus 822 light source CEx1 Comparative Example 1 CEx2 Comparative Example 2 Ex1 Example 1 Ex1 to 8 Examples 1 to 8 Ex9 Example 9 h120 Height of convex portion h320 Height of convex portion p120x Arrow indicating pitch p120y Arrow indicating pitch p320x Arrow indicating pitch p320y Arrow indicating pitch p320z Arrow indicating pitch w121 Length of one side of top surface (minor diameter) w122 Length of one side of bottom surface (minor diameter) w321 Diameter of top surface (minor diameter) w322 Diameter of bottom surface (minor diameter)

Claims

1. An anti-reflection member having an anti-reflection layer, the anti-reflection layer being located on the outermost surface of the anti-reflection member and constituting an anti-reflection surface, the anti-reflection layer having a base layer and a concave-convex structure consisting of a number of convex portions provided on the base layer, and satisfying the following formulas (e1) to (e4): w ２ / h>1 (e1) 0.9≦n ｅｆｆ / (n ｂ ) １／２ ≦1.1 (e2) 0.6≦(h・n ｅｆｆ ) / 137.5≦1.5 (e3) w ２ < 400 (e4) However, w ２ is the minor axis (nm) of the bottom surface of the protrusion, h is the height (nm) of the protrusion, and n ｅｆｆ is a value represented by the following formula (e5), ｅｆｆ = n ｐ × (V ｐ / (V ｐ +V ｖ )) + n ｖ × (V ｖ / (V ｐ +V ｖ )) Formula (e5) n ｂ is the refractive index of the material constituting the base layer, and n ｐ is the refractive index of the material constituting the convex portion, and V ｐ and V ｖ are the volume occupied by the protrusions and the volume occupied by the gaps between the protrusions in the region from the top of the protrusions to a depth h, respectively, and n ｖ is the refractive index of the material that constitutes the void.

2. The anti-reflection member according to claim 1, which has a front reflectance of 1.5% or less over the entire wavelength range of 400 to 700 nm.

3. A method for producing an anti-reflective member according to claim 1 or 2, comprising: step 1 of applying a coating liquid for forming a resin layer onto a substrate to form a coating liquid layer; and step 2 of transferring a concave-convex shape to the coating liquid layer, irradiating it with energy rays to cure it, and forming an anti-reflective layer.

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