JP6385977B2 - Optical body and display device - Google Patents

Description

  The present invention relates to an optical body and a display device.

  In general, in an optical element such as a display device such as a television or a camera lens, an antireflection treatment is performed on a surface on which light is incident in order to improve the amount of light transmitted.

  Conventionally, as one of such antireflection treatments, for example, a micro uneven structure (for example, a moth-eye structure) whose average period of unevenness is equal to or less than a wavelength belonging to the visible light band is formed on a light incident surface. It has been proposed. On the surface having such a micro concavo-convex structure, since the change in refractive index with respect to incident light becomes gentle, there is no sudden change in refractive index that causes reflection. Therefore, reflection of incident light can be prevented over a wide wavelength band by forming such a micro uneven structure on the light incident surface.

  In addition, it is desired to superimpose the above-described micro uneven structure on the surface of a macro uneven structure having unevenness larger than that of the micro uneven structure. Examples of the macro uneven structure include an anti-glare (anti-glare) structure in which a rough surface structure is formed on the surface to scatter incident light, or a micro lens array structure in which a plurality of lenses are two-dimensionally arranged. It is done.

  Therefore, Patent Document 1 below discloses a technique of superimposing a micro uneven structure on an antiglare structure in which larger unevenness than the micro uneven structure is formed by an anodic oxidation method.

International Publication 2011/052652

  However, since the technique disclosed in Patent Document 1 employs wet etching as a method for forming the micro uneven structure, the micro uneven structure is isotropically formed on the surface of the antiglare structure. As a result, the protrusions of the micro concavo-convex structure extended in the normal direction of the tangential plane at each position on the surface of the antiglare structure.

  In such a superposed structure, the extension direction of the protrusions in the micro concavo-convex structure is not aligned in the direction normal to the flat surface of the base material, so that the antireflection performance against strong external light from the front surface is reduced. was there.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved optical body with improved antireflection performance, and a display device including the optical body. It is to provide.

  In order to solve the above problems, according to one aspect of the present invention, a first uneven structure formed on a surface of a base material and a second uneven structure superimposed on the first uneven structure, The average period of the irregularities of the first uneven structure is larger than the wavelength belonging to the visible light band, and the average period of the irregularities of the second uneven structure is equal to or less than the wavelength belonging to the visible light band, The protrusions of the second concavo-convex structure extend in the direction normal to the flat surface of the substrate, are periodically arranged in a hexagonal lattice shape or a rectangular lattice shape, and the 20 ° gloss is 4% or less. An optical body is provided.

  The protrusions of the second concavo-convex structure are ridge-side protrusions formed on the ridges of the first concavo-convex structure, valley-side protrusions formed on the valleys of the first concavo-convex structure, An intermediate protrusion formed on a slope between the peak and the valley of the first concavo-convex structure, and the height of the intermediate protrusion is such that the height of the peak and the valley May be different.

  The spectroscopic luminous reflectance of the optical body may be 0.3% or less, and the haze value of the optical body may be 5% or more.

  The protrusions of the second concavo-convex structure may be arranged with a period of 100 nm or more and 350 nm or less.

  The substrate may be a resin film.

  Moreover, in order to solve the said subject, according to another viewpoint of this invention, a display apparatus provided with said optical body is provided.

  According to the present invention, the projecting portion of the second concavo-convex structure can be extended in the normal direction to the flat surface of the base material, so that regular reflection with respect to external light can be suppressed.

  As described above, according to the present invention, the projection of the second concavo-convex structure extends in the normal direction of the flat surface of the base material, so that the antireflection performance of the optical body can be improved. is there.

It is sectional drawing which shows typically the cross-sectional shape at the time of cut | disconnecting the optical body which concerns on one Embodiment of this invention to the thickness direction. 1B is an enlarged cross-sectional view schematically showing an enlarged partial region X in FIG. 1A. FIG. It is a top view which shows an example of the planar arrangement | sequence of the optical body which concerns on the embodiment. It is sectional drawing explaining each process of the 1st manufacturing method of the optical body which concerns on the same embodiment. It is sectional drawing explaining each process of the 1st manufacturing method of the optical body which concerns on the same embodiment. It is sectional drawing explaining each process of the 1st manufacturing method of the optical body which concerns on the same embodiment. It is sectional drawing explaining each process of the 1st manufacturing method of the optical body which concerns on the same embodiment. It is sectional drawing explaining each process of the 1st manufacturing method of the optical body which concerns on the same embodiment. It is sectional drawing explaining each process of the 1st manufacturing method of the optical body which concerns on the same embodiment. It is sectional drawing explaining each process of the 1st manufacturing method of the optical body which concerns on the same embodiment. It is sectional drawing explaining each process of the 1st manufacturing method of the optical body which concerns on the same embodiment. It is explanatory drawing explaining the etching of the micro uneven structure in the etching process shown by FIG. 3G. It is a perspective view explaining the optical body original disk for manufacturing the optical body which concerns on the embodiment. It is explanatory drawing which showed an example of the exposure apparatus which manufactures the optical body original disc shown in FIG. It is explanatory drawing which showed an example of the etching apparatus which manufactures the optical body original disk shown in FIG. It is explanatory drawing which showed an example of the transfer apparatus which manufactures the optical body which concerns on the embodiment. 3 is a SEM image of the surface of the optical body according to Example 1. 10 is a SEM image of the surface of an optical body according to Example 3. 2 is a TEM image of a macro uneven structure of an optical body according to Example 1. FIG. 2 is a TEM image of a micro uneven structure of an optical body according to Example 1. FIG. It is explanatory drawing explaining the optical system of regular reflection spectroscopy measurement. It is explanatory drawing explaining the optical system of diffuse reflection spectroscopy measurement. It is a graph which shows the measurement result of the spectral regular reflectance in regular reflection. It is a graph which shows the measurement result of the spectral diffuse reflectance in diffuse reflection.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<1. About optical bodies>
[1.1. Structure of optical body]
First, the structure of an optical body according to an embodiment of the present invention will be described with reference to FIGS. 1A to 2. FIG. 1A is a cross-sectional view schematically showing a cross-sectional shape when the optical body 1 according to this embodiment is cut in the thickness direction. As shown in FIG. 1A, the optical body 1 according to the present embodiment overlaps the macro uneven structure 13 (corresponding to the first uneven structure) formed on the surface of the substrate 11 and the macro uneven structure 13. And a micro concavo-convex structure 14 (corresponding to a second concavo-convex structure).

  The base material 11 is comprised with the material which has transparency. As a material constituting the substrate 11, for example, a transparent resin such as polycarbonate, polyethylene terephthalate, or polymethyl methacrylate, a resin film such as cellulose triacetate (TAC), or a cyclic olefin copolymer (COC), or quartz glass And transparent glass such as soda-lime glass or lead glass. In addition, the material which comprises the base material 11 is not limited to said material, As long as it is transparent, you may use another well-known material.

  In the above, “transparent” means that the transmittance of light having a wavelength belonging to the visible light band (approximately 360 to 830 nm) is high. For example, the transmittance of the light is 70% or more. means.

The macro concavo-convex structure 13 is a concavo-convex structure formed on the base material 11, and as shown in FIG. 1A, the valley portion 13 </ b> A that is concave with respect to the flat surface 12 of the base material 11 and the flatness of the base material 11. A ridge 13C that is convex with respect to the surface 12. In addition, a slope portion 13B is formed between the valley portion 13A and the mountain portion 13C adjacent to each other. The average period of the unevenness of the macro uneven structure 13 according to the present embodiment is larger than the wavelength belonging to the visible light band (for example, more than 830 nm), and preferably 1 μm or more and 100 μm or less. Here, the average period of the irregularities in the macro uneven structure 13 is shown in Figure 1A, adjacent valleys 13A, between 13A, or crest portion 13C, which corresponds to the average distance _{P 1} between 13C.

  The macro uneven structure 13 may be, for example, an antiglare (antiglare) structure in which the average period of unevenness is 1 μm or more and 100 μm or less. The macro uneven structure 13 may be a microlens array structure in which a plurality of lenses having a diameter of 1 μm to 100 μm are two-dimensionally arranged on the XY plane in FIG. 1A. In the following description, the case where the macro uneven structure 13 has an anti-glare structure will be described as an example.

The micro concavo-convex structure 14 is an concavo-convex structure formed so as to overlap the macro concavo-convex structure 13, and as shown in FIG. 1A, a plurality of protrusions 141 extending in the normal direction of the flat surface 12 of the substrate 11 and , And a bottom part 143 located between the adjacent projecting parts 141 and 141. The average period of the unevenness of the micro uneven structure 14 according to the present embodiment is not more than a wavelength belonging to the visible light band (for example, not more than 830 nm), and preferably not less than 100 nm and not more than 350 nm. Here, the average period of the irregularities in the micro uneven structure 14 is shown in FIG. 1A, which corresponds to the average distance P ₂ between the vertices of the projections 141, 141 adjacent to each other.

  In the micro concavo-convex structure 14 having such a structure, for example, a plurality of protrusions 141 extending in the normal direction of the flat surface of the substrate 11 are periodically two-dimensionally arranged on the XY plane of the substrate 11 shown in FIG. 1A. A moth-eye structure may be used. Here, the two-dimensional array in the XY plane in FIG. 1A of the protrusions 141 of the micro concavo-convex structure 14 may be an array having a predetermined periodicity, or a random array having no periodicity. Also good. However, the two-dimensional arrangement of the protrusions 141 in the XY plane is preferably an arrangement having a predetermined periodicity as described later with reference to FIG.

  Here, in the optical body 1 according to the present embodiment, all the protrusions 141 constituting the micro concavo-convex structure 14 extend in the normal direction (that is, the Z direction) of the flat surface 12 of the substrate 11. Thereby, in the optical body 1, since the extending direction of the protrusions 141 of the micro concavo-convex structure 14 is aligned over the entire substrate 11, the antireflection ability when strong external light enters the optical body 1 can be further improved. it can.

  On the other hand, although not shown, when the protrusion 141 extends in the normal direction of the tangent plane at each position on the surface of the macro uneven structure 13 as in the prior art, the protrusion 141 of the micro uneven structure 14 The extending direction changes depending on which surface of the valley portion 13A, the slope portion 13B, and the mountain portion 13C of the concavo-convex structure 13 is formed. In such an optical body, since the extending direction of the protrusion 141 is not uniform in the entire base material 11, the antireflection performance when strong external light enters the optical body is reduced.

  Next, the micro uneven structure 14 will be described more specifically with reference to FIGS. 1B and 2. FIG. 1B is an enlarged cross-sectional view schematically showing an enlarged partial region X of FIG. 1A. FIG. 2 is a top view showing an example of a planar arrangement of the optical body 1 according to the present embodiment.

  As shown in FIG. 1B, the protrusion 141 of the micro uneven structure 14 includes a valley side protrusion 141A formed on the valley 13A of the macro uneven structure 13 and an intermediate protrusion formed on the inclined surface 13B of the macro uneven structure 13. Part 141 </ b> B and a peak-side protrusion 141 </ b> C formed on the peak 13 </ b> C of the macro uneven structure 13.

In the optical element 1 according to the present embodiment, as schematically shown in FIG. 1B, the height h _B of the middle protrusion 141B is the valley side protrusion 141A of the height h _A and the mountain side projections 141C height it is preferable that different from the h _C. The height _{h B} of the intermediate protruding portion 141B is lower than the height _{h C} of height _{h A} and the mountain side protrusion 141C of the valley side protrusion 141A is more preferable. The wavelength band of light that can prevent reflection in the micro uneven structure 14 depends on the height of the protrusion 141. Therefore, the protrusion 141 of the micro concavo-convex structure 14 includes the valley-side protrusion 141A and the peak-side protrusion 141C, and the intermediate protrusion 141B having a height lower than these protrusions, thereby preventing reflection. The wavelength band of incident light that can be generated can be widened. For example, when the height h _A of the valley-side protrusion 141A and the height h _{C of the} peak-side protrusion 141C are 300 nm or more and 400 nm or less, the height h _B of the intermediate protrusion 141B is 200 nm or more and 300 nm or less. preferable.

Here, as shown in FIG. 1B, assuming baseline connecting virtually between two bottom 143A positioned on both sides of the vertex T _A, Law of the flat surface 12 of the substrate 11 from the vertex T _A Let B _{A be} the intersection of the straight line drawn along the linear direction (Z direction) and the baseline. At this time, the height of the valley-side protrusion 141A described above corresponds to the distance between the vertex T _A and the intersection B _A. Similarly, the height of the intermediate protruding portion 141B is a vertex _{T B} shown in FIG. 1B - corresponds to the distance between the intersections _{B B,} the height of the mountain-side protrusion 141C the vertex _{T C} shown in FIG. 1B - intersection corresponding to the distance between B _C.

Further, as shown in FIG. 2, the protrusions 141 of the micro concavo-convex structure 14 follow a plurality of rows of tracks (for example, tracks T1, T2, T3, etc.) forming a predetermined interval _PT in the Y direction in FIG. Are arranged. In each track T, the protrusions 141 are arranged at a constant period along the X direction in FIG.

Here, the protrusions 141 are arranged so that, for example, the vertex interval between the protrusions 141 adjacent to each other is equal to or less than the wavelength belonging to the visible light band. Specifically, as shown in FIG. 2, the protrusion 141 includes an arrangement interval (dot pitch) P _{D of} the protrusion 141 in each track and an arrangement interval (track pitch) P between the tracks of the protrusion 141. Each of _T is arranged to be equal to or less than a wavelength belonging to the visible light band.

For example, the dot pitch _{P D} and the track pitch _{P T,} and at 100nm than 350nm or less, preferably is 150nm or more 280nm or less, respectively. Here, if any of the dot pitch P _D and the track pitch P _T is less than 100 nm, is not preferable because the formation of the micro uneven structure 14 becomes difficult. Also, if any of the dot pitch P _D and the track pitch P _T exceeds 350 nm, undesirable since there is a possibility that diffraction of visible light occurs. The size of the dot pitch P _D and the track pitch P _T may be the same as each other or may be different.

  Further, the multiple rows of tracks on which the protrusions 141 are arranged may be linear as illustrated in FIG. 2, but the present invention is not limited to such illustration. For example, the plurality of rows of tracks on which the protrusions 141 are arranged may be curved.

Furthermore, although FIG. 2 shows an example in which the protrusions 141 are arranged in a rectangular lattice shape on the XY plane of the base material 11, the present invention is not limited to such illustration. For example, the protrusions 141 are arranged in a staggered manner in which the arrangement pitch (dot pitch P _D ) of the protrusions 141 is shifted by a half-dot pitch between adjacent tracks, and the protrusions 141 have a hexagonal shape on the XY plane of the substrate 11. It may be arranged. In order to increase the filling rate of the protrusions 141 on the XY plane, the protrusions 141 are more preferably arranged in a hexagonal shape.

[1.2. Characteristics of optical body]
Next, the optical characteristics of the optical body 1 according to this embodiment having the structure described above will be described.

  In the optical body 1 according to the present embodiment, as described above, the average period of the unevenness is equal to or less than the wavelength belonging to the visible light band with respect to the macro uneven structure 13 in which the average period of the unevenness is larger than the wavelength belonging to the visible light band. A certain micro uneven structure 14 is superimposed. Thereby, the optical body 1 which concerns on this embodiment can have both high antireflection ability and high anti-glare ability.

  Specifically, in the optical body 1 according to the present embodiment, the specular specular reflectance is 0.3% or less, and the haze value is 5% or more. Preferably, in the optical body 1 according to the present embodiment, the specular specular reflectance is 0.3% or less, and the haze value is 10% or more. Spectral specular reflectance is a Y value when the color of specular reflection light with respect to incident light is expressed in the Yxy color system, and represents the brightness of the color of specular reflection light. That is, the lower the specular specular reflectance, the higher the antireflection performance. The haze value is the ratio of the diffuse transmittance to the total light transmittance of the light incident on the optical body. The higher the haze value, the higher the light scattering property of the optical body and the higher the antiglare performance. The optical body 1 according to the present embodiment has an antireflection ability by having a low spectral regular reflectance, and can have a high antiglare ability by having a high haze value.

  The spectroscopic luminous reflectance value is preferably smaller, and no lower limit value is provided. However, it may be larger than 0%, for example. Moreover, since the value of a haze value differs depending on the use, an upper limit is not particularly provided, but it may be less than 100%, for example.

  In addition, as described above, the optical body 1 according to the present embodiment suppresses regular reflection with respect to external light because the extending direction of the protrusion 141 is aligned with the normal direction of the flat surface 12 of the base material 11. can do.

  Specifically, the glossiness at 20 ° (incident angle) of the optical body 1 according to this embodiment is 4% or less, more preferably less than 1%. The glossiness is a value representing the degree of specular reflection light with respect to incident light. The lower the glossiness, the more regular reflection is suppressed. The optical body 1 according to the present embodiment can suppress regular reflection and prevent glare and the like even when receiving strong external light.

  The gloss value is not particularly set to a lower limit value, but may be larger than 0%, for example.

  The structure and characteristics of the optical body 1 according to this embodiment have been described in detail above. According to this embodiment, an optical body with improved light transmittance can be realized by increasing the antireflection ability.

<2. About optical body manufacturing method>
[2.1. First production method]
Then, with reference to FIG. 3A-FIG. 4, the 1st manufacturing method of the optical body 1 which concerns on this embodiment is demonstrated. 3A to 3H are cross-sectional views illustrating each step of the first method for manufacturing the optical body 1 according to this embodiment.

  Specifically, in the first manufacturing method of the optical body 1 according to the present embodiment, first, the micro uneven structure 14 is formed on the substrate 11, and then the macro uneven structure 13 is formed on the micro uneven structure 14. To overlap.

  In the first manufacturing method, first, as shown in FIG. 3A, a first resist layer 15 is formed on a substrate 11 such as quartz glass. Here, as the first resist layer 15, either an organic resist or an inorganic resist can be used. As the organic resist, for example, a novolac resist or a chemically amplified resist can be used. As the inorganic resist, for example, a metal oxide containing one or more transition metals such as tungsten or molybdenum can be used.

  Next, as shown in FIG. 3B, the first resist layer 15 is exposed by an exposure device, and a latent image 15 </ b> A is formed on the first resist layer 15. Specifically, the portion of the first resist layer 15 irradiated with the electromagnetic wave 20 by irradiating the first resist layer 15 with the high-energy electromagnetic wave 20 such as laser light, ultraviolet light, X-rays, or electron beam. Denatures to form a latent image 15A.

  Subsequently, as shown in FIG. 3C, a developer is dropped onto the first resist layer 15 on which the latent image 15A is formed, and the first resist layer 15 is developed. As a result, a predetermined pattern is formed on the first resist layer 15. For example, when the first resist layer 15 is a positive resist, the exposed portion exposed with the electromagnetic wave 20 has a higher dissolution rate in the developer than the non-exposed portion. Therefore, as shown in FIG. 3C, the exposed portion (latent image 15A) is removed by development processing, and a pattern from which the latent image 15A has been removed is formed on the first resist layer 15. On the other hand, when the first resist layer 15 is a negative resist, the exposed portion exposed by the electromagnetic wave 20 has a lower dissolution rate in the developer than the non-exposed portion. Therefore, the non-exposed portion is removed by the development process, and a pattern in which the latent image 15 </ b> A remains is formed on the first resist layer 15.

  Next, as shown in FIG. 3D, the base material 11 is etched using the first resist layer 15 patterned in the previous step as a mask. Thereby, the micro uneven structure 14 (second uneven structure) is formed on the substrate 11. As the etching method for the base material 11, either dry etching or wet etching can be used. However, in order to form the micro concavo-convex structure 14 in which the average period of the concavo-convex is equal to or less than the wavelength belonging to the visible light band at a high aspect ratio, it is more preferable to use dry etching that facilitates obtaining vertical anisotropy.

  The etching conditions for the base material 11 can be appropriately set by considering the materials of the base material 11 and the first resist layer 15. For example, when quartz glass is used for the substrate 11, dry etching using a CF-based gas and a gas containing H, or wet etching using hydrofluoric acid or the like is used to form the micro uneven structure 14. be able to.

  Subsequently, as shown in FIG. 3E, the second resist layer 16 is formed on the base material 11 on which the micro uneven structure 14 is formed. The second resist layer 16 is formed, for example, by dropping an organic resist such as a photo-curable resist or a thermoplastic resist on the substrate 11. Further, as the second resist layer 16, an inorganic resist such as a metal oxide or spin on glass (SOG) can be used.

  However, the material which comprises the 2nd resist layer 16 is selected so that the etching rate of the 2nd resist layer 16 may differ from the etching rate of the base material 11 in the etching process of the base material 11 mentioned later. For example, when the base material 11 is an inorganic material such as quartz glass, the second resist layer 16 is preferably an organic resist. Moreover, when the base material 11 is organic materials, such as transparent resin, it is preferable that the 2nd resist layer 16 is inorganic resists, such as a spin on glass.

  Next, as shown in FIG. 3F, the macro uneven structure 13 (first uneven structure) is formed in the second resist layer 16. Here, as described above, the macro uneven structure 13 formed in the second resist layer 16 is an uneven structure in which the average period of the unevenness is larger than the wavelength belonging to the visible light band. The macro concavo-convex structure 13 may be formed, for example, by imprinting a transfer film on which the structure in which the concavo-convex structure of the macro concavo-convex structure 13 is inverted is formed on the second resist layer 16. The macro uneven structure 13 may be formed by subjecting the second resist layer 16 to machining such as sandblasting.

  Subsequently, as shown in FIG. 3G, the base material 11 is etched using the second resist layer 16 patterned in the previous step as a mask. Thereby, both the macro uneven structure 13 and the micro uneven structure 14 are superimposed on the base material 11.

  Here, in this etching step, etching having vertical anisotropy is used as etching for the base material 11. Specifically, it is preferable to use reactive ion etching (RIE) for etching the base material 11 using the second resist layer 16 as a mask. By using etching having such vertical anisotropy, the macro uneven structure 13 can be formed on the base material 11 without losing the micro uneven structure 14 in this etching step.

  On the other hand, in etching having isotropic properties such as wet etching, the etching also proceeds on the side surfaces of the protrusions 141 of the micro concavo-convex structure 14 as in the vertical direction. As a result, the micro uneven structure 14 disappears during etching, and it becomes difficult to superimpose the macro uneven structure 13 and the micro uneven structure 14 on the substrate 11. Therefore, it is not preferable to use etching having isotropic properties such as wet etching.

  Moreover, in the etching with respect to the base material 11, it is preferable that the etching rate of the 2nd resist layer 16 and the etching rate of the base material 11 differ from each other.

(1) First Etching Conditions Under the first etching conditions, the etching rate of the second resist layer 16 is slower than the etching rate of the base material 11. More specifically, the ratio between the etching rate of the second resist layer 16 and the etching rate of the substrate 11 is preferably 1: 1.2 to 1:20.

  For example, when the etching rate ratio of the base material 11 to the second resist layer 16 is less than 1.2, the micro uneven structure 14 formed on the base material 11 disappears after etching, which is not preferable. Moreover, when the etching rate ratio of the base material 11 with respect to the 2nd resist layer 16 exceeds 20, since the uneven | corrugated depth of the macro uneven structure 13 becomes large after an etching and the optical characteristic of the optical body 1 falls, it is unpreferable. .

In this first etching condition, when the substrate 11 is quartz glass, the gas used in the etching preferably contains carbon atoms, fluorine atoms, and hydrogen atoms. Quartz (SiO ₂ ) can be etched by including carbon atoms and fluorine atoms in the gas used for etching. Further, by containing hydrogen atoms in the gas used for etching, a hydrocarbon film is formed on the side wall of the etching pattern during the etching, so that the side wall of the pattern can be protected and the vertical anisotropy of etching can be increased. Under the first etching conditions, since high vertical anisotropy is required for etching, it is preferable to use a gas containing carbon atoms, fluorine atoms, and hydrogen atoms to increase the vertical anisotropy of etching. On the other hand, when the gas used for etching does not contain hydrogen atoms, the vertical anisotropy of etching is not sufficient, which is not preferable.

Specifically, when the substrate 11 is quartz glass, CHF ₃ , CH ₂ F ₂ gas, or the like can be used. It is also possible to use a gas in which H ₂ is mixed with a gas such as CF ₄ , C ₂ F ₈ , or C ₃ F ₈ . Furthermore, it is possible to add an inert gas such as Ar gas to the gas used in the etching. However, a chemically active gas such as O ₂ gas is not preferable because it increases the isotropy of etching and lowers the vertical anisotropy.

  Furthermore, the etching with respect to the micro uneven structure 14 under the first etching condition will be further described.

  Under the first etching condition, the micro concavo-convex structure 14 is protected from etching by the second resist layer 16. Here, the protrusions 141 of the micro concavo-convex structure 14 are exposed first after the upper second resist layer 16 is removed faster than the bottom 143. Since the etching rate to the base material 11 is faster than the etching rate to the second resist layer 16, the previously exposed protrusion 141 proceeds to be etched faster, and is etched deeper than the bottom 143 when the etching is completed. The Therefore, when the etching is completed, a new bottom is formed at the position where the protrusion 141 was formed before the main etching step, and a new protrusion is formed at the position where the bottom 143 was formed. That is, the micro concavo-convex structure 14 is superimposed on the macro concavo-convex structure 13 in a state where the positions of the protrusion 141 and the bottom 143 are reversed by this etching process.

  Furthermore, with reference to FIG. 4, the inversion of the unevenness of the micro uneven structure 14 will be described more specifically. FIG. 4 is an explanatory view for explaining the etching of the micro concavo-convex structure 14 in the etching step shown in FIG. 3G.

  As shown in FIG. 4A, before the main etching process, the protrusions 141 and the bottom 143 of the micro concavo-convex structure 14 are formed on the base material 11, and the second resist layer 16 is filled in the valleys corresponding to the bottom 143. Yes. When this etching process is performed on such a micro concavo-convex structure 14, as shown in FIG. 4B, the base material 11 is formed first from the protruding portion 141 where the thickness of the upper second resist layer 16 is thin. It is exposed and etching of the substrate 11 proceeds. Here, since the protrusion 141 formed on the substrate 11 has a higher etching rate than the second resist layer 16, the etching amount is larger than that of the second resist layer 16 filled in the bottom 143. Further, when the etching of the base material 11 proceeds, as shown in FIGS. 4C and 4D, the protrusion 141 exposed earlier is etched deeper than the bottom 143 where the upper second resist layer 16 is thick. become.

  Therefore, as shown in FIG. 4E, when etching is performed until the second resist layer 16 disappears, the protrusion 141 before the etching process is etched deeper than the bottom 143 before the etching process, and becomes a new bottom 147. Further, the bottom portion 143 before the etching process has a smaller amount of etching than the protrusion 141 before the etching process, and thus becomes a new protrusion 145.

  As described above, when the etching rate of the second resist layer 16 is slower than the etching rate of the base material 11, the micro concavo-convex structure 14 formed on the base material 11 is positioned between the protrusion 141 and the bottom 143. Is superimposed on the macro uneven structure 13 in a reversed state.

(2) Second Etching Condition In contrast to the first etching condition, the etching rate of the second resist layer 16 may be faster than the etching rate of the substrate 11. More specifically, the etching rate ratio of the second resist layer 16 to the base material 11 may be 1.5 or more.

  For example, when the etching rate ratio of the second resist layer 16 to the base material 11 is less than 1.5, the unevenness depth of the micro uneven structure 14 formed on the base material 11 is reduced after the etching, and the optical body 1 This is not preferable because the characteristics deteriorate. Moreover, the upper limit of the etching rate ratio of the second resist layer 16 to the base material 11 is not particularly provided, but may be, for example, 20 or less.

In this second etching condition, when the substrate 11 is quartz glass, the gas used preferably contains carbon atoms and fluorine atoms. Quartz (SiO ₂ ) can be etched by using a gas containing carbon atoms and fluorine atoms for etching.

Specifically, when the base material 11 is quartz glass, CHF ₃ , CH ₂ F ₂ , CF ₄ , C ₂ F ₈ , C ₃ F ₈ gas, or the like is used as a gas used in the etching. be able to. Further, with respect to these gases, it is also possible to add H ₂ gas or Ar gas or the like. However, a chemically active gas such as O ₂ gas is not preferable because it increases the isotropy of etching and lowers the vertical anisotropy.

  Further, etching for the micro uneven structure 14 under the second etching condition will be described.

  Under the second etching condition, the micro concavo-convex structure 14 is protected from etching by the second resist layer 16. Here, since the etching rate to the base material 11 is slower than the etching rate to the second resist layer 16, the macro uneven structure 13 formed on the base material 11 is the macro uneven structure formed on the second resist layer 16. The unevenness becomes smaller than 13. On the other hand, since the formation amount of the unevenness of the macro uneven structure 13 with respect to the base material 11 is small, the micro uneven structure 14 formed on the base material 11 before the main etching process remains without disappearing. Therefore, the micro uneven structure 14 can be superimposed on the macro uneven structure 13 also by this etching process.

  However, under the present etching conditions, the height of the protrusion 141 of the micro concavo-convex structure 14 is lower than that before etching, so that the antireflection performance may be reduced. For this reason, it is more preferable to use the first etching condition in which the etching rate of the second resist layer 16 is slower than the etching rate of the substrate 11 rather than the second etching condition.

  Next, as shown in FIG. 3H, the remaining second resist layer 16 is removed from the base material 11 on which both the macro uneven structure 13 and the micro uneven structure 14 are superimposed. Moreover, the optical body 1 which concerns on this embodiment is manufactured by wash | cleaning the base material 11 from which the 2nd resist layer 16 was removed.

  According to the first manufacturing method described above, the optical body 1 according to this embodiment can be manufactured. Further, since the optical body 1 manufactured by the first manufacturing method is etched with vertical anisotropy in the etching step shown in FIG. 3G, the protrusion 141 of the micro uneven structure 14 is formed as a base material. 11 in the normal direction of the flat surface 12. Therefore, the optical body 1 can suppress regular reflection with respect to strong external light as described above.

  In the first manufacturing method, since etching having vertical anisotropy is performed in the etching step shown in FIG. 3G, the intermediate protrusion 141B of the micro concavo-convex structure 14 includes the valley-side protrusion 141A and the peak side. The height is lower than the protrusion 141C. Therefore, as described above, the optical body 1 manufactured by the first manufacturing method can prevent reflection of incident light in a wider wavelength band.

  In etching having vertical anisotropy, ions are incident perpendicularly to the flat surface 12 of the base material 11, and therefore the trough portions 13 </ b> A and the crest portions 13 </ b> C whose surfaces protrude from the ion incident direction are etched. It is easy to receive the energy of contributing ions. In addition, in the slope portion 13B having an angle with respect to the incident direction of ions, ion energy contributing to etching is dispersed. Thereby, the etching rate of the slope portion 13B is slower than the etching rates of the valley portion 13A and the peak portion 13C. Therefore, the intermediate protrusion 141B has a lower height than the valley-side protrusion 141A and the peak-side protrusion 141C.

  Furthermore, in the first manufacturing method, since the micro uneven structure 14 is patterned by lithography using an exposure apparatus, the micro uneven structure 14 has a range in which visible diffracted light is not periodically generated on the surface of the substrate 11. The protrusion 141 can be formed. Therefore, the optical body 1 according to the present embodiment can suppress incident light transmission loss due to diffraction scattering.

[2.2. Second production method]
Then, with reference to FIGS. 5-8, the 2nd manufacturing method of the optical body 1 which concerns on this embodiment is demonstrated. FIG. 5 is a perspective view for explaining an optical body master 1A for manufacturing the optical body 1 according to the present embodiment. 6 is an explanatory view showing an example of an exposure apparatus for producing the optical master 1A shown in FIG. 5, and FIG. 7 shows an example of an etching apparatus for producing the optical master 1A shown in FIG. FIG. Further, FIG. 8 is an explanatory view showing an example of a transfer device for manufacturing the optical body 1 according to the present embodiment.

  Specifically, in the second manufacturing method of the optical body 1 according to the present embodiment, first, the optical body master 1A on which the uneven structure 5 on which the macro uneven structure 13 and the micro uneven structure 14 are superimposed is formed. To manufacture. Next, the optical body 1 having the concavo-convex structure 5 formed on the surface of the substrate 11 is continuously manufactured by transferring the concavo-convex structure 5 to the sheet-like base material 11 using the manufactured optical body master 1A. To do.

  First, the optical body master 1A will be described with reference to FIG. As shown in FIG. 5, the optical master 1 </ b> A is made of, for example, a hollow cylindrical master 3. In addition, an uneven structure 5 is formed on the outer peripheral surface of the master base material 3.

The master base material 3 is, for example, a cylindrical glass body, and is formed of, for example, quartz glass. However, the material of the master base material 3 is not particularly limited as long as it has high SiO ₂ purity, and may be fused silica glass or synthetic quartz glass. Further, the size of the master base material 3 is not particularly limited. For example, the axial length may be 100 mm or more, the outer diameter may be 50 mm or more and 300 mm or less, and the thickness. 2 mm or more and 50 mm or less may be sufficient.

  The concavo-convex structure 5 is a macro concavo-convex structure (first concavo-convex structure) in which the average period of concavo-convex is larger than the wavelength belonging to the visible light band, and the micro concavo-convex structure (first 2 concavo-convex structure). Here, the macro uneven structure may be, for example, an antiglare structure having an average period of unevenness of 1 μm to 100 μm, and the micro uneven structure is, for example, a moth-eye structure having an average period of unevenness of 100 nm to 350 nm. Also good.

  The optical master 1A having such an uneven structure 5 formed on the outer peripheral surface can be manufactured by using, for example, the manufacturing method described above as the first manufacturing method. Specifically, the optical master 1A can be manufactured by using the exposure apparatus 2 shown in FIG. 6 and the etching apparatus 4 shown in FIG.

  Here, with reference to FIG. 6 and FIG. 7, the exposure apparatus 2 and the etching apparatus 4 for manufacturing the optical disc 1A will be described.

  First, the exposure apparatus 2 shown in FIG. 6 will be described. The exposure apparatus 2 shown in FIG. 6 is a laser drawing apparatus used in the exposure process described with reference to FIG. 3B.

  As shown in FIG. 6, the exposure apparatus 2 includes a laser light source 21, a first mirror 23, a photodiode (Photodiode: PD) 24, a condenser lens 26, and an electro-optic deflector (Electro Optical Deflector: EOD). 29, a collimator lens 28, a control mechanism 37, a second mirror 31, a moving optical table 32, a spindle motor 35, and a turntable 36. The master base material 3 is placed on the turntable 36 and can rotate.

  The laser light source 21 is a light source that oscillates a laser beam 20A for exposing a resist layer formed on the surface of the master substrate 3, and is, for example, a semiconductor that emits a laser beam having a wavelength in a blue light band of 400 nm to 500 nm. It is a laser. The laser light 20 </ b> A emitted from the laser light source 21 travels straight as a parallel beam and is reflected by the first mirror 23. Further, the laser light 20 </ b> A reflected by the first mirror 23 is condensed on the electro-optic deflection element 29 by the condenser lens 26, and then converted into a parallel beam again by the collimator lens 28. The parallel laser beam 20 </ b> A is reflected by the second mirror 31 and guided horizontally and parallel onto the moving optical table 32.

  The first mirror 23 is composed of a polarization beam splitter, and has a function of reflecting one of the polarization components and transmitting the other of the polarization components. The polarized light component transmitted through the first mirror 23 is received by the photodiode 24 and subjected to photoelectric conversion. The light reception signal photoelectrically converted by the photodiode 24 is input to the laser light source 21, and the laser light source 21 modulates the laser light 20A based on the input light reception signal.

  The electro-optic deflection element 29 is an element that can control the irradiation position of the laser light 20A. The exposure apparatus 2 can also change the irradiation position of the laser light 20 </ b> A guided onto the moving optical table 32 by the electro-optic deflection element 29.

  The moving optical table 32 includes a beam expander (BEX) 33 and an objective lens 34. The laser beam 20A guided to the moving optical table 32 is shaped into a desired beam shape by the beam expander 33, and then irradiated to the resist layer formed on the surface of the master substrate 3 through the objective lens 34. Is done. Further, the master base material 3 is placed on a turntable 36 connected to a spindle motor 35 so that it can rotate.

  Here, while rotating the master base material 3 by the turntable 36, the laser light 20A is moved in the axial direction of the master base material 3, and the resist layer is irradiated with laser light intermittently, thereby exposing the resist layer. Done. The laser beam 20A is moved by moving the moving optical table 32 in the arrow R direction.

  Further, the exposure apparatus 2 includes a control mechanism 37 for making the irradiation position with the laser light 20A into a two-dimensional pattern such as a rectangular lattice shape or a hexagonal lattice shape. The control mechanism 37 includes a formatter 38 and a driver 39, and controls the irradiation of the laser light 20A. The driver 39 controls the output of the laser light source 21 based on the control signal generated by the formatter 38. Thereby, irradiation of the laser beam 20A to the resist layer 15 is controlled.

  The exposure apparatus 2 synchronizes the control signal from the formatter 38 and the servo signal of the spindle motor 35 for each track so that the two-dimensional pattern is synchronized for each track. Therefore, by setting the rotation number of the turntable 36, the modulation frequency of the laser light 20A, the feed pitch of the moving optical table 32, and the like to appropriate values, the exposure apparatus 2 can form the resist layer in a periodic two-dimensional pattern. Can be irradiated with the laser beam 20A.

  Next, the etching apparatus 4 shown in FIG. 7 will be described. The etching apparatus 4 is used in the etching process described with reference to FIGS. 3D and 3G. The etching apparatus 4 shown in FIG. 7 is, for example, an RIE (Reactive Ion Etching) apparatus.

  As shown in FIG. 7, the etching apparatus 4 includes an etching reaction tank 41, a cylindrical electrode 42 that is a cathode (cathode), and a counter electrode 43 that is an anode (anode). The cylindrical electrode 42 is provided in the center of the etching reaction tank 41, and the master base material 3 is provided in a detachable manner. The cylindrical electrode 42 preferably has, for example, a cylindrical surface that is substantially the same as or similar to the master base material 3 and has a smaller cylindrical surface than the inner peripheral surface of the master base material 3. The cylindrical electrode 42 is connected to a high frequency power supply (RF) 45 having a frequency of 13.56 MHz, for example, via a blocking capacitor 44. On the other hand, the counter electrode 43 is provided inside the etching reaction tank 41 and connected to the ground.

  In the etching apparatus 4, plasma is generated between the counter electrode 43 and the cylindrical electrode 42 by applying a high frequency voltage between the counter electrode 43 and the cylindrical electrode 42 by the high frequency power supply 45. Here, since the counter electrode 43 is connected to the ground, the potential does not change. On the other hand, since the circuit of the cylindrical electrode 42 is interrupted by a blocking capacitor, a voltage drop occurs and the potential becomes negative. As a result, an electric field is generated in the etching reaction tank 41 in a direction perpendicular to the cylindrical surface of the cylindrical electrode 42, so that positive ions in the plasma are perpendicularly incident on the outer peripheral surface of the master substrate 3, and Etching having a directivity can be performed.

  The optical master 1A shown in FIG. 5 can be manufactured by executing the steps described in the first manufacturing method using the exposure apparatus 2 and the etching apparatus 4 described above.

  Furthermore, the optical body 1 according to this embodiment can be manufactured by transferring the concavo-convex structure 5 formed on the outer peripheral surface of the optical body master 1 </ b> A to the base material 11. Specifically, the optical body 1 according to the present embodiment can be manufactured by using a transfer device 6 shown in FIG.

  Here, with reference to FIG. 8, the transfer apparatus 6 for manufacturing the optical body 1 using the optical body master 1A will be described. The transfer device 6 shown in FIG. 8 is, for example, a roll-to-roll type nanoimprint apparatus.

  As shown in FIG. 8, the transfer device 6 includes an optical master 1 </ b> A, a base material supply roll 51, a winding roll 52, guide rolls 53 and 54, a nip roll 55, a peeling roll 56, and a coating apparatus 57. And a light source 58.

  The base material supply roll 51 is a roll in which the base material 11 in the form of a sheet is wound in a roll shape. The take-up roll 52 is a roll for taking up the optical body 1 on which the resin layer 62 to which the uneven structure 5 is transferred is laminated. The guide rolls 53 and 54 are rolls for transporting the base material 11 and are arranged on the transport path in the transfer device 6 so that the base material 11 can be transported from the base material supply roll 51 to the take-up roll 52.

  The nip roll 55 is a roll for bringing the base material 11 on which the resin layer 62 is laminated into close contact with the cylindrical optical master 1A. Moreover, after the concavo-convex structure 5 is transferred to the resin layer 62, the peeling roll 56 peels the base material 11 on which the resin layer 62 is laminated from the optical body master 1A. The material of the substrate supply roll 51, the take-up roll 52, the guide rolls 53 and 54, the nip roll 55, and the peeling roll 56 is not particularly limited. For example, a metal such as stainless steel, rubber, silicone resin, or the like is appropriately selected. Can be used.

  The coating device 57 includes coating means such as a coater, and applies the photocurable resin composition to the substrate 11 to form the resin layer 62. The coating device 57 may be, for example, a gravure coater, a wire bar coater, a die coater, or the like. The light source 58 is a light source that emits light having a wavelength capable of curing the photocurable resin composition, and may be, for example, an ultraviolet lamp.

  In addition, a photocurable resin composition is resin which fluidity | liquidity falls and is hardened | cured by irradiating the light of a predetermined wavelength. Specifically, the photocurable resin composition may be an ultraviolet curable resin such as an acrylic resin acrylate. Moreover, the photocurable resin composition may contain an initiator, a filler, a functional additive, a solvent, an inorganic material, a pigment, an antistatic agent, a sensitizing dye, or the like, if necessary.

As the initiator, for example, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, etc. are used. May be. As the filler, either inorganic fine particles or organic fine particles can be used. For example, metal oxide fine particles such as SiO ₂ , TiO ₂ , ZrO ₂ , SnO ₂ , and Al ₂ O ₃ are used as the inorganic fine particles. Can do. Moreover, as a functional additive, a leveling agent, a surface conditioner, an absorber, an antifoamer etc. can be used, for example.

  In the transfer device 6, first, the base material 11 is continuously sent out from the base material supply roll 51 through the guide roll 53. The sent base material 11 is coated with the photocurable resin composition by the coating device 57, the resin layer 62 is laminated, and is further brought into close contact with the optical body master 1 </ b> A by the nip roll 55. Thereby, the concavo-convex structure 5 formed on the outer peripheral surface (that is, the transfer surface) of the optical body master 1 </ b> A is transferred to the resin layer 62. After the concavo-convex structure 5 is transferred, the resin layer 62 is cured by light irradiation from the light source 58. Subsequently, the base material 11 (optical body 1) on which the cured resin layer 62 is laminated is peeled from the optical master 1 </ b> A by the peeling roll 56, conveyed by the guide roll 54, and then wound by the winding roll 52. Taken.

  Thereby, the sheet-like optical body 1 to which the concavo-convex structure 5 formed on the optical body master 1A is transferred can be continuously manufactured.

  By using each device described above, the second manufacturing method of the optical body according to the present embodiment can be performed.

  Specifically, the first resist layer 15 is formed on the outer peripheral surface of the master base material 3 made of cylindrical quartz glass, and thermal lithography using laser light is performed by the exposure apparatus 2 shown in FIG. A latent image 15 A is formed on the layer 15. Subsequently, the exposed master base material 3 is developed to form a pattern on the first resist layer 15, and then the master base material 3 is etched by the etching apparatus 4 shown in FIG. A micro uneven structure 14 is formed on the surface.

  Next, the second resist layer 16 is formed on the outer peripheral surface of the master base material 3 on which the micro uneven structure 14 is formed, and the macro uneven structure 13 is formed on the second resist layer 16. Subsequently, the master base material 3 is etched by the etching apparatus 4 shown in FIG. 7, and the macro uneven structure 13 and the micro uneven structure 14 are superimposed on the outer peripheral surface of the master base material 3. By these steps, the optical master 1A in which the micro uneven structure 14 is superimposed on the macro uneven structure 13 is manufactured.

  Further, the optical body 1 is manufactured by transferring the concavo-convex structure 5 on the outer peripheral surface of the optical disk master 1A manufactured as described above to the base material 11 by the transfer device 6 shown in FIG.

  According to the second manufacturing method, the uneven structure 5 can be transferred from the optical master 1A to the optical body 1 by using a roll-to-roll nanoimprint technique. High-speed and continuous production is possible.

  In the above, the optical master 1A has been described as a cylindrical glass body, but the present invention is not limited to the above examples. For example, the optical master 1A may be a flat glass body. In such a case, the concavo-convex structure 5 can be transferred from the optical disk master 1 </ b> A to the optical body 1 by using the single wafer transfer device 6.

  In the above, the manufacturing method of the optical body 1 which concerns on this embodiment was demonstrated.

<3. Example>
Hereinafter, the optical body 1 according to the embodiment will be specifically described with reference to Examples and Comparative Examples. In addition, the Example shown below is one example of conditions for showing the feasibility and effects of the optical body 1 and the manufacturing method thereof according to the above embodiment, and the optical body 1 and the manufacturing method of the present invention are as follows. The present invention is not limited to the examples.

[3.1. Production of optical body]
The optical body 1 was manufactured by the following steps.

Example 1
First, the first resist layer 15 containing tungsten metal oxide was formed on the outer peripheral surface of the master base material 3 made of cylindrical quartz glass. Next, thermal lithography using a laser beam was performed by the exposure apparatus 2 shown in FIG. 6, and a hexagonal lattice-shaped dot array pattern latent image 15 </ b> A was formed on the first resist layer 15.

  In the exposed dot array pattern, dots are arranged at predetermined dot pitches along tracks in the circumferential direction of the master base material 3, and adjacent tracks are alternately shifted by a half dot pitch (hexagonal lattice shape). Array). The dot pitch in the same track is about 230 nm, and the track pitch in the axial direction of the master base material 3 is about 150 nm.

Subsequently, the exposed resist was dissolved by developing the master base material 3 with an alkali developer (NMD3 manufactured by Tokyo Ohka Kogyo Co., Ltd.), and a dot array pattern was formed on the first resist layer 15. Next, using the first resist layer 15 as a mask, the master base material 3 is etched using CHF ₃ gas by the etching apparatus 4 shown in FIG. 7, and the micro uneven structure 14 is formed on the outer peripheral surface of the master base material 3. Formed. In this etching step, the master base material 3 was etched until the height of the protrusion 141 of the micro uneven structure 14 was about 250 nm.

  Further, a second resist layer 16 was formed by applying a cationic polymerization type nanoimprint lithography resist, which is an ultraviolet curable resin, in a solvent to the master base material 3 on which the micro uneven structure 14 was formed. Thereafter, the master base material 3 was heated at 100 ° C. for 5 minutes to remove the solvent in the second resist layer 16.

Here, the rough surface film in which the macro uneven structure 13 was formed was brought into close contact with the second resist layer 16, and the second resist layer 16 was cured by irradiating ultraviolet rays at 1000 mJ / cm ² . Thereafter, the rough film was peeled off, and the macro uneven structure 13 was formed on the second resist layer 16. The arithmetic average roughness Ra of the macro uneven structure 13 of the rough surface film was 0.449 μm. In addition, arithmetic mean roughness Ra of the rough surface film was measured at a measurement speed of 100 μm / sec and a measurement force of 100 μN using a Kosaka Laboratory Surfcoder ET200.

Subsequently, using the second resist layer 16 on which the macro uneven structure 13 is formed as a mask, the etching apparatus 4 shown in FIG. 7 uses the CHF ₃ gas and the master at a gas pressure of 0.5 Pa and an input power of 250 W. The substrate 3 was etched for 6 hours. The ratio between the etching rate of the second resist layer 16 and the etching rate of the master base material 3 in this etching was approximately 1: 2.

  By this etching process, the macro uneven structure 13 and the micro uneven structure 14 were superimposed on the surface of the master base material 3. The arithmetic average roughness Ra of the master base material 3 after etching was 0.707 μm.

Through the above steps, the optical master 1A in which the micro uneven structure 14 is superimposed on the macro uneven structure 13 is manufactured. Subsequently, the macro concavo-convex structure 13 and the micro concavo-convex structure 14 formed on the outer peripheral surface of the optical master 1A were transferred to the resin layer 62 by the transfer device 6 shown in FIG. A polyethylene terephthalate film was used as the base material 11 of the optical body 1. The resin layer 62 was cured by irradiating with 1000 mJ / cm ² ultraviolet rays using an acrylic resin acrylate which is an ultraviolet curable resin.

(Example 2)
In Example 1, the optical body 1 was produced in the same manner as in Example 1 except that the arithmetic average roughness Ra of the rough film adhered to the second resist layer 16 was changed to 0.187 μm. . The arithmetic average roughness Ra of the master base material 3 after etching was 0.385 μm.

(Example 3)
In Example 1, the arithmetic average roughness Ra of the rough surface film closely adhered to the second resist layer 16 is changed to 0.606 μm, and the etching for forming the macro uneven structure 13 on the master base material 3 is performed. An optical body 1 was produced in the same manner as in Example 1 except that the gas used in 1 was changed to CF ₄ . Note that the ratio of the etching rate of the second resist layer 16 to the etching rate of the master base material 3 in this etching is approximately 3: 1, and the arithmetic average roughness Ra of the master base material 3 after etching is 0. 271 μm.

Example 4
In Example 1, the optical body 1 was produced in the same manner as in Example 1 except that the arithmetic average roughness Ra of the rough film adhered to the second resist layer 16 was changed to 0.12 μm. . The arithmetic average roughness Ra of the master base material 3 after etching was 0.186 μm.

(Comparative Example 1)
A polyethylene terephthalate film was used as the base material 11 and an AG (Antiglare) layer having a haze value of 7% was laminated on one side of the base material 11 by wet coating. On the AG layer, SiO _x (film thickness 3 nm), Nb ₂ O ₅ (film thickness 20 nm), SiO ₂ (film thickness 35 nm), Nb ₂ O ₅ (film thickness 35 nm), and SiO ₂ (film thickness 100 nm) in this order. An optical body was manufactured by forming a multilayer thin film by sputtering and forming an antireflection layer.

(Comparative Example 2)
A cellulose triacetate (TAC) film was used as the base material 11, and an AG hard coat layer having a haze value of 9% was laminated on one side of the base material 11 by wet coating. Next, an optical body was manufactured by laminating a resin layer containing a filler and having a refractive index lower than that of the AG hard coat layer by wet coating to form an antireflection layer.

(Comparative Example 3)
In Example 1, the optical body was prepared in the same manner as in Example 1 except that the master base material 3 on which only the micro uneven structure 14 before the macro uneven structure 13 was formed was used as the optical master 1A. 1 was produced.

(Comparative Example 4)
A commercially available anti-glare film (manufactured by Daiso) in which an antiglare layer having a haze value of about 20% and a hard coat layer were laminated on a polyethylene terephthalate film was purchased and used as an optical body.

[3.2. Evaluation results of optical body]
(Optical microscope observation results)
First, with reference to FIG. 9 to FIG. 12, the results of structural observation of an optical body using a scanning electron microscope (SEM) and a transmission electron microscope (TEM) will be described.

  First, the planar structure of the optical body was observed with an SEM. The results are shown in FIG. 9 and FIG. Here, FIG. 9 is an SEM image of the surface of the optical body according to Example 1, and FIG. 10 is an SEM image of the surface of the optical body according to Example 3. 9A and 10A are SEM images with a magnification of 5000 times, and FIGS. 9B and 10B are SEM images with a magnification of 50000 times.

  Referring to FIGS. 9A and 10A, it can be seen that a micrometer-scale uneven structure is formed on the surfaces of the optical bodies according to Examples 1 and 3. This micrometer scale concavo-convex structure corresponds to a macro concavo-convex structure (first concavo-convex structure) in which the average period of concavo-convex is larger than the wavelength belonging to the visible light band. It can also be seen that a finer micro uneven structure (second uneven structure) is superimposed on the macro uneven structure on the surface of the macro uneven structure of the optical bodies according to Examples 1 and 3.

  9B and 10B, in the micro uneven structure formed on the surface of the optical body according to Examples 1 and 3, the protrusions are formed in a two-dimensional array having periodicity. Recognize. Specifically, it can be seen that the two-dimensional array of protrusions in the micro concavo-convex structure is an array having a so-called hexagonal lattice periodicity in which the rows of protrusions arranged at equal intervals are staggered. .

  Next, the cross-sectional structure of the optical body was observed with a TEM. The results are shown in FIG. 11 and FIG. FIG. 11 is a TEM image of the macro uneven structure of the optical body according to Example 1. FIG. 12 is a TEM image of the micro uneven structure of the optical body according to Example 1. Of these, FIG. 12A is a TEM image in which the peak portion of the macro uneven structure is enlarged, FIG. 12B is a TEM image in which the slope portion of the macro uneven structure is enlarged, and FIG. It is the expanded TEM image.

  Referring to FIG. 11, it can be seen that the protrusions of the micro concavo-convex structure of the optical body according to Example 1 extend in the normal direction of the flat surface of the base material and are aligned in one direction over the entire base material. .

  Furthermore, referring to FIGS. 12A to 12C, the protrusions of the micro uneven structure extend in the normal direction of the flat surface of the base material on the surfaces of the crests, valleys, and slopes in the macro uneven structure of the optical body. It can be seen that it is formed. In addition, the height of the intermediate protrusion formed on the inclined surface of the macro uneven structure is the height of the valley side protrusion formed on the valley of the macro uneven structure, and the peak side formed on the peak of the macro uneven structure. It can be seen that it is lower than the height of the protrusion. Specifically, the height of the intermediate protrusion was about 270 nm to 300 nm, and the height of the valley side protrusion and the peak side protrusion was about 360 to 390 nm.

  In FIGS. 12A to 12C, assuming a base line that virtually connects two bottom portions located on both sides of the apex of a certain protrusion, the normal direction of the flat surface of the base material extends from the apex. The distance between the lowered straight line and the intersection of the base line was measured as the height of the protrusion.

(Evaluation of antireflection performance of optical body)
Subsequently, with reference to FIG. 13A to FIG. 15, the evaluation result of the antireflection ability of the optical body according to the present embodiment will be described. FIG. 13A is an explanatory diagram for explaining an optical system for specular reflection spectrometry, and FIG. 13B is an explanatory diagram for explaining an optical system for diffuse reflectance spectrometry. FIG. 14 is a graph showing the measurement result of spectral regular reflectance in regular reflection, and FIG. 15 is a graph showing the measurement result of spectral diffuse reflectance in diffuse reflection.

  First, with reference to FIG. 13A and FIG. 13B, the evaluation method of the antireflection ability of the optical body according to this embodiment will be described. As shown in FIG. 13A, in specular reflection spectrometry, the light 72A from the light source 71 is directly applied to the sample 77. The reflected light 72 </ b> B from the sample 77 is collected by the spherical mirror 73, guided to the integrating sphere 75, then multiple-reflected in the integrating sphere 75 and homogenized, and then detected. Further, as shown in FIG. 13B, in the diffusion spectroscopic measurement, the light 72A from the light source 71 is reflected by the spherical mirror and then irradiated on the sample 77 provided in the integrating sphere 75. The reflected light 72B from the sample 77 is detected after multiple reflection in the integrating sphere 75 and homogenization.

  Here, the measurement result of the spectral regular reflectance in regular reflection is shown in FIG. 14, and the measurement result of the spectral diffuse reflectance in diffuse reflection is shown in FIG. For the reflectance measurement, a spectrophotometer V550 manufactured by JASCO and an absolute reflectance measuring instrument ARV474S were used.

  As shown in FIG. 14, the optical bodies according to Examples 1 to 4 have a lower spectral regular reflectance at any wavelength belonging to the visible light band than Comparative Examples 1 to 4, and can prevent regular reflection. I know that there is.

  On the other hand, in Comparative Example 1 in which the antireflection ability is imparted by the multilayer thin film, only regular wavelength light of 450 nm or more and 650 nm or less can prevent regular reflection, and in the wavelength band of less than 450 nm or more than 650 nm, It can be seen that the light regular reflectance increases. Further, Comparative Example 2 imparted with antireflection ability by the resin layer and Comparative Example 4 which is a commercially available anti-glare film have higher spectral regular reflectance than Examples 1 to 4, and sufficiently prevent regular reflection. You can't do it. Further, Comparative Example 3 in which only the micro uneven structure is formed has a relatively high spectral regular reflectance for Examples 1 to 4, although the spectral regular reflectance is relatively low at any wavelength belonging to the visible light band. I understand.

  Further, as shown in FIG. 15, the optical bodies according to Examples 1 to 4 have a relatively low spectral diffuse reflectance over the entire visible light band as compared with Comparative Examples 1 and 2, and can prevent diffuse reflection. I know that there is.

  However, the spectral diffuse reflectance of the optical body according to Example 3 was higher than the spectral diffuse reflectance of the optical body according to Examples 1 and 2. This is presumably because, in Example 3, the etching rate of the resist layer is faster than the etching rate of the master base material in the etching step of superimposing the micro uneven structure on the macro uneven structure. In Example 3, the height of the protrusions of the micro uneven structure is lower than that in Examples 1 and 2 and Comparative Example 3 due to the above etching conditions. Thereby, in Example 3, it is thought that the anti-reflective capability fell and the spectral diffuse reflectance increased.

  On the other hand, it can be seen that Comparative Example 1 provided with the antireflection ability by the multilayer thin film can only prevent diffuse reflection of light in a limited wavelength band of 450 nm or more and 650 nm or less. Specifically, it can be seen that in Comparative Example 1, the spectral diffuse reflectance increases with respect to Examples 1 to 4 in the wavelength band of less than 450 nm or more than 650 nm. Moreover, it turns out that the comparative example 2 which provided the antireflection ability with the resin layer has high spectral diffuse reflectance with respect to Examples 1-4, and cannot fully prevent diffuse reflection. Furthermore, it turns out that the comparative example 3 which formed only the micro uneven | corrugated structure shows the same spectral diffuse reflectance as Example 1, 2, and 4. FIG.

Furthermore, the color tone of regular reflection light of the optical body according to the present embodiment was measured, and luminous reflectance (Y) and reflection chromaticity (a ^* , b ^* ) were calculated. Here, the luminous reflectance of regular reflected light (also referred to as spectral regular luminous reflectance) is the Y value of (Y, x, y) when the color of regular reflected light is expressed in the Yxy color system. And represents the brightness of the color of the specularly reflected light. That is, the lower the specular specular reflectance, the lower the brightness of the specularly reflected light, indicating that specular reflection is suppressed. The reflection chromaticity (a ^* , b ^* ) indicates the color tone of the regular reflection light. A haze meter HM-150 manufactured by Murakami Color Research Laboratory was used to measure the color tone of the regular reflection light. The measurement results are shown in Table 1 below.

  Referring to Table 1, the optical bodies according to Examples 1 to 4 have a lower spectral specular reflectance (Y value) than the optical bodies according to Comparative Examples 1 to 4, and the brightness of the color of the specularly reflected light is low. You can see that it is lower. That is, it can be seen that the optical bodies according to Examples 1 to 4 are less regularly reflected than the optical bodies according to Comparative Examples 1 to 4. Specifically, it can be seen that the spectroscopic luminous reflectance (Y value) of the optical bodies according to Examples 1 to 4 is 0.3% or less. On the other hand, the spectroscopic luminous reflectance of the optical bodies according to Comparative Examples 1 to 4 is higher than 0.3%, and the optical bodies according to Comparative Examples 1 to 4 cannot suppress regular reflection. Recognize.

(Evaluation result of transparency of optical body)
Subsequently, the evaluation result of the transparency of the optical body according to the present embodiment will be described. Specifically, the haze value and the total light transmittance were measured for the optical bodies according to Examples 1 to 4 and Comparative Examples 1 to 4. Here, the haze value is an index representing the turbidity (cloudiness) of the optical body, and the higher the value, the higher the light scattering property of the optical body and the higher the antiglare ability. The total light transmittance is an index representing the transparency of the optical body. Note that a haze meter HM-150 manufactured by Murakami Color Research Laboratory was used to measure the haze value and total light transmittance. The measurement results are shown in Table 2 below.

  Referring to Table 2, the optical bodies according to Examples 1 to 4 have the same total light transmittance as the optical bodies according to Comparative Examples 1 to 4, and the haze value is high, so the transparency is high. And it turns out that anti-glare ability is high. Specifically, it can be seen that the haze values of Examples 1 to 4 are 5% or more, more specifically 10% or more.

  From the above evaluation results, it can be seen that the optical bodies according to Examples 1 to 4 have both antireflection ability and antiglare ability. In the optical bodies according to Examples 1 to 4, the average period of irregularities is less than or equal to the wavelength belonging to the visible light band with respect to the macro uneven structure where the average period of irregularities is larger than the wavelength belonging to the visible light band on the surface. This is because a certain micro uneven structure is superimposed. On the other hand, since the optical bodies according to Comparative Examples 1 to 4 do not have such a superimposed structure, they cannot have both antireflection ability and antiglare ability.

(Evaluation result of glossiness of optical body)
Next, the evaluation result of the glossiness of the optical body according to the present embodiment will be described. Specifically, the glossiness was measured for the optical bodies according to Examples 1 to 4 and Comparative Examples 1 to 4. Here, the glossiness is an index representing the glossiness of the optical body, and the higher the value, the higher the light scattering property of the optical body, the higher the matte degree, and the higher the antiglare performance.

  In addition, the haze meter HM-150 made from Murakami Color Research Laboratory was used for the measurement of glossiness. The 20 ° glossiness represents the reflectance at a light receiving angle of 20 ° when light is projected onto the optical body surface at an incident angle of 20 °, and the 60 ° glossiness is applied to the optical body surface at an incident angle of 60 °. The reflectance at a light receiving angle of 60 ° when light is projected is represented, and the 80 ° glossiness represents the reflectance at a light receiving angle of 80 ° when light is projected onto the optical surface at an incident angle of 80 °. The measurement results are shown in Table 3 below.

  Referring to Table 3, since the optical bodies according to Examples 1 to 4 have a lower glossiness than the optical bodies according to Comparative Examples 1 to 4, the optical bodies have high light scattering properties and high antiglare performance. I understand that. Specifically, it can be seen that the 20 ° glossiness of the optical bodies according to Examples 1 to 4 is 4% or less, more specifically, less than 1%. Moreover, it turns out that the 60 degree glossiness of the optical body which concerns on Examples 1-4 becomes 10% or less.

  On the other hand, the 20 ° glossiness of the optical bodies according to Comparative Examples 1 to 4 is 1% or more, and the 60 ° glossiness is higher than 10%. Therefore, the optical bodies according to Comparative Examples 1 to 4 are used. Shows that the light scattering property is low and the antiglare property is low.

[3.3. Evaluation of actual optical body]
Next, with reference to FIG. 16 and 17, the evaluation result at the time of using the optical body which concerns on this embodiment as an antireflection film is demonstrated. Specifically, it was evaluated whether or not the external light reflection can be prevented and the visibility of the liquid crystal display can be improved when the optical body according to the present embodiment is attached to the liquid crystal display.

(Example 5)
An optical body according to Example 2 of the present invention was attached to an iPodTouch (registered trademark) liquid crystal display through an adhesive layer having a refractive index of 1.5 to obtain Example 5.

(Comparative Examples 5 to 8)
As in Example 5, the optical bodies according to Comparative Examples 1 to 4 were attached to an iPodTouch liquid crystal display through an adhesive layer having a refractive index of 1.5 to obtain Comparative Examples 5 to 8.

(Comparative Example 9)
An iPodTouch liquid crystal display without affixing anything was used as Comparative Example 9.

  The liquid crystal display according to Example 5 and Comparative Examples 5 to 9 is irradiated with light from a 27 W 3-wavelength daylight white fluorescent lamp from the front, and is regularly reflected at each of the white display unit and the black display unit. The light to be measured was measured with a luminance meter. In addition, the contrast ratio of the liquid crystal display was calculated by dividing the luminance of the white display portion during external light irradiation by the luminance of the black display portion. Furthermore, the brightness | luminance of the white display part in the state (dark place) which does not irradiate external light was measured with respect to the liquid crystal display which concerns on Example 5 and Comparative Examples 5-9. Note that a luminance meter CS1000 manufactured by Konica Minolta was used for luminance measurement.

  Table 4 below shows the evaluation results of the contrast ratio at the time of external light irradiation of the liquid crystal display displays according to Example 5 and Comparative Examples 5 to 9 measured above and the luminance evaluation result of the white display portion in the dark place. Shown in

  Referring to Table 4, it can be seen that the liquid crystal display according to Example 5 has a higher contrast ratio between the white display part and the black display part when exposed to external light than the liquid crystal display displays according to Comparative Examples 5 to 9. . That is, the liquid crystal display according to Example 5 can prevent external light reflection more than the liquid crystal display displays according to Comparative Examples 5 to 9, and suppress a decrease in contrast ratio due to external light reflection. I understand that I can do it.

  Further, referring to Table 4, the liquid crystal display according to Example 5 has substantially the same luminance in the dark place as the liquid crystal display according to Comparative Examples 5 to 9. Therefore, it can be seen that the liquid crystal display according to the fifth embodiment transmits light without being attenuated while having high antireflection performance.

  From the above results, it was shown that the optical body according to the present embodiment can be suitably used as an antireflection film, and improves the visibility of a liquid crystal display in an environment where strong external light is irradiated. .

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Optical body 11 Base material 12 Flat surface 13 Macro uneven structure 13A Valley part 13B Slope part 13C Mountain part 14 Micro uneven structure 141 Protrusion part 141A Valley side protrusion part 141B Intermediate protrusion part 141C Mountain side protrusion part 143 Bottom part

Claims (3)

A first uneven structure formed on the surface of the substrate;
A second concavo-convex structure superimposed on the first concavo-convex structure;
With
The average period of the unevenness of the first uneven structure is larger than the wavelength belonging to the visible light band,
The average period of the unevenness of the second uneven structure is not more than a wavelength belonging to the visible light band,
The protrusions of the second concavo-convex structure extend in a direction normal to the flat surface of the base material, and are periodically arranged in a hexagonal lattice shape or a rectangular lattice shape,
The protrusions of the second concavo-convex structure are arranged with a period of 100 nm to 350 nm,
The protrusions of the second concavo-convex structure are ridge-side protrusions formed on the ridges of the first concavo-convex structure, valley-side protrusions formed on the valleys of the first concavo-convex structure, An intermediate protrusion formed on the slope between the peak and the valley of the first concavo-convex structure,
The height of the intermediate protrusion is different from the peak-side protrusion and the valley-side protrusion,
Spectral specular reflectance is 0.3% or less,
The haze value is 5% or more,
An optical body having a 20 ° gloss of 4% or less. A first uneven structure formed on the surface of the substrate;
A second concavo-convex structure superimposed on the first concavo-convex structure;
With
The average period of the unevenness of the first uneven structure is larger than the wavelength belonging to the visible light band,
The average period of the unevenness of the second uneven structure is not more than a wavelength belonging to the visible light band,
The protrusions of the second concavo-convex structure extend in a direction normal to the flat surface of the base material, and are periodically arranged in a hexagonal lattice shape or a rectangular lattice shape,
The protrusions of the second concavo-convex structure are ridge-side protrusions formed on the ridges of the first concavo-convex structure, valley-side protrusions formed on the valleys of the first concavo-convex structure, An intermediate protrusion formed on the slope between the peak and the valley of the first concavo-convex structure,
The height of the intermediate protrusion is different from the peak-side protrusion and the valley-side protrusion,
Spectral specular reflectance is 0.3% or less,
The haze value is 5% or more,
An optical body having a 20 ° gloss of 4% or less. A first uneven structure formed on the surface of the substrate;
A second concavo-convex structure superimposed on the first concavo-convex structure;
With
The average period of the unevenness of the first uneven structure is larger than the wavelength belonging to the visible light band,
The average period of the unevenness of the second uneven structure is not more than a wavelength belonging to the visible light band,
The protrusions of the second concavo-convex structure extend in a direction normal to the flat surface of the base material, and are periodically arranged in a hexagonal lattice shape or a rectangular lattice shape,
The protrusions of the second concavo-convex structure are arranged with a period of 100 nm to 350 nm,
The protrusions of the second concavo-convex structure are ridge-side protrusions formed on the ridges of the first concavo-convex structure, valley-side protrusions formed on the valleys of the first concavo-convex structure, An intermediate protrusion formed on the slope between the peak and the valley of the first concavo-convex structure,
The height of the intermediate protrusion is different from the peak-side protrusion and the valley-side protrusion,
An optical body having a 20 ° gloss of 4% or less.