WO2021145339A1 - Color-development structure and method for manufacturing color-development structure - Google Patents

Abstract

This color-development structure is provided with: a corrugated layer having a corrugated structure that is equipped with a flat surface and protrusions disposed on said flat surface; and a dielectric layer that has a surface having a shape conforming to the corrugated structure, and that is formed of a single-layer thin film that emits reflected light that has been enhanced by interference. The protrusions are so structured as to have one or more steps above the flat surface. When viewed from a viewpoint opposing the surface of the corrugated layer, the protrusions are arranged so as to form a pattern that includes a set of multiple figurative elements each having a first length not more than a subwavelength along a first direction and a second length not less than the first length along a second direction that is orthogonal to the first direction. In the multiple figurative elements, the standard deviation of the second lengths is greater than that of the first lengths.

Description

Color-developing structure and manufacturing method of color-developing structure

The present disclosure relates to a colored structure exhibiting a structural color and a method for manufacturing the colored structure.

The structural color that is often observed as the color of living organisms in the natural world such as morpho butterflies is the color that is visually recognized by the action of optical phenomena caused by the fine structure of an object, such as diffraction, interference, and scattering of light. For example, structural color due to multilayer film interference is generated when light is reflected at the interface between thin films adjacent to each other and the reflected light interferes with each other. Multilayer interference is one of the wing coloring principles of Morpho butterflies. In the wing of a morpho butterfly, in addition to multi-layer film interference, light is scattered and diffracted by the fine uneven structure on the surface of the wing, and as a result, bright blue color is visually recognized at a wide observation angle.

As described in Patent Document 1, as a structure that artificially reproduces the structural color like the wing of a morpho butterfly, a multilayer film layer is laminated on the surface of a base material having fine irregularities arranged unevenly. Structure has been proposed. In a structure in which a multilayer film layer is laminated on a flat surface, the wavelength of the reflected light that is visually recognized changes greatly depending on the observation angle, so that the color that is visually recognized changes greatly depending on the observation angle. On the other hand, in the structure of Patent Document 1, since the reflected light enhanced by the interference spreads in multiple directions due to the irregular unevenness, the color change depending on the observation angle becomes gentle. As a result, a structure that exhibits a specific color at a wide observation angle, such as the wing of a morpho butterfly, is realized.

Japanese Unexamined Patent Publication No. 2005-153192

However, in the manufacturing process of the multilayer film layer, it is necessary to sequentially laminate a plurality of thin films with a precise film thickness so that the thin films formed from different materials are adjacent to each other. Therefore, the load required to manufacture the structure in which the multilayer film layer is laminated on the fine uneven structure as described above is large.

An object of the present disclosure is to provide a color-developing structure capable of suppressing a color change due to a change in an observation angle with a simple configuration, and a method for manufacturing the color-developing structure.

In one aspect, a coloring structure is provided. The color-developing structure has a concavo-convex layer having a concavo-convex structure having a flat surface and a convex portion located on the flat surface, and a surface having a shape following the concavo-convex structure, and emits reflected light enhanced by interference. It includes a dielectric layer made of a single-layer thin film. The convex portion has one or more steps from the plane. Seen from a viewpoint facing the surface of the uneven layer, the convex portion has a first length that is equal to or less than a sub-wavelength along the first direction and the first along a second direction orthogonal to the first direction. They are arranged to form a pattern that includes a set of a plurality of graphic elements, each having a second length that is greater than or equal to one. In the plurality of graphic elements, the standard deviation of the second length is larger than the standard deviation of the first length. The extinction coefficient of the material of the dielectric layer in the visible region has the smallest value in the wavelength range of the dominant color in the reflected light, and has the largest value in the wavelength range other than the dominant color.

In another aspect, a coloring structure is provided. The color-developing structure has a concavo-convex layer having a concavo-convex structure having a flat surface and a convex portion located on the flat surface, and a surface having a shape following the concavo-convex structure, and emits reflected light enhanced by interference. It includes a dielectric layer made of a single-layer thin film. The convex portion has one or more steps from the plane. Seen from a viewpoint facing the surface of the uneven layer, the convex portion has a first length that is equal to or less than a sub-wavelength along the first direction and the first along a second direction orthogonal to the first direction. They are arranged to form a pattern that includes a set of a plurality of graphic elements, each having a second length that is greater than or equal to one. In the plurality of graphic elements, the standard deviation of the second length is larger than the standard deviation of the first length. The dielectric layer is composed of a metal compound of any one of a metal oxide, a metal nitride, and a metal oxynitride, and the metal compound has a composition in which a metal element is excessive more than a chemical quantitative composition.

In another aspect, a method for manufacturing a colored structure is provided. The method has a concave-convex structure in which a flat surface and a convex portion located on the flat surface are provided on the base material by transferring the unevenness of the concave plate to a base material using a step of forming a concave plate and an imprint method. The dielectric layer composed of a single thin film having a surface having a shape following the uneven structure and emitting reflected light enhanced by interference is erased in the visible region. The step of forming the decay coefficient from a material having the smallest value in the wavelength range of the dominant color in the reflected light and having the largest value in the wavelength range other than the dominant color is included. The convex portion has one or more steps from the plane. Seen from a viewpoint facing the surface of the resin layer, the convex portion has a first length that is equal to or less than a sub-wavelength along the first direction, and the first along a second direction orthogonal to the first direction. It is arranged so as to form a pattern including a set of a plurality of graphic elements each having a second length equal to or greater than one. In the plurality of graphic elements, the standard deviation of the second length is larger than the standard deviation of the first length.

In another aspect, a method for manufacturing a colored structure is provided. The method has a concave-convex structure in which a flat plate and a convex portion located on the flat surface are provided on the base material by transferring the unevenness of the concave plate to a base material using a step of forming a concave plate and an imprint method. A metal oxide, a metal, a dielectric layer composed of a single thin film having a surface having a shape following the uneven structure and emitting reflected light enhanced by interference, and a step of forming a resin layer having the above. It comprises a step of forming from the metal compound which is either a nitride or a metal oxynitride and has a composition in which a metal element is excessive than a chemical quantitative composition. The convex portion has one or more steps from the plane. Seen from a viewpoint facing the surface of the resin layer, the convex portion has a first length that is equal to or less than a sub-wavelength along the first direction, and the first along a second direction orthogonal to the first direction. It is arranged so as to form a pattern including a set of a plurality of graphic elements each having a second length equal to or greater than one. In the plurality of graphic elements, the standard deviation of the second length is larger than the standard deviation of the first length.

The figure which shows the cross-sectional structure of the color-developing structure which has the concavo-convex structure of the 1st structure about 1st Embodiment of a color-developing structure. FIG. 2A is a diagram showing a planar structure of the concave-convex structure of the first structure, and FIG. 2B is a diagram showing a cross-sectional structure of the concave-convex structure of the first structure. The figure which shows the cross-sectional structure of the color-developing structure which has the concavo-convex structure of the second structure about the color-developing structure of 1st Embodiment. FIG. 4A is a diagram showing a planar structure of a concave-convex structure composed of only the second convex element, and FIG. 4B is a diagram showing a cross-sectional structure of the concave-convex structure composed of only the second convex element. FIG. 5A is a diagram showing a planar structure of the concave-convex structure of the second structure, and FIG. 5B is a diagram showing a cross-sectional structure of the concave-convex structure of the second structure. The figure which shows the change according to the wavelength of the refractive index and the extinction coefficient of _{TiO 2.} The figure which shows the change according to the wavelength of the refractive index and the extinction coefficient of _{TiO x.} The figure which shows the change according to the wavelength of the refractive index and the extinction coefficient of aluminum. The figure which shows the change according to the wavelength of the refractive index and the extinction coefficient of polyethylene terephthalate. The figure which shows the wavelength of the reflected light when each of _{TiO 2} and TiO _{x is used.} The figure which shows the cross-sectional structure of the color-developing structure about the 2nd Embodiment of a color-developing structure. The figure which shows the cross-sectional structure of the color-developing structure of a modification.

(First Embodiment)
The first embodiment of the color-developing structure and the method for manufacturing the color-developing structure will be described with reference to FIGS. 1 to 10. The incident light and reflected light targeted by the color-developing structure are light in the visible region. In the following description, the light in the visible region refers to the light in the wavelength region of 360 nm or more and 830 nm or less.

[Coloring structure]
As shown in FIG. 1, the color-developing structure 10 includes a base material 12, a resin layer 13 which is an example of an uneven layer, a dielectric layer 14, and a reflective layer 15.

The base material 12 is a flat layer and supports the resin layer 13. The base material 12 is composed of a material that transmits light in the entire visible region, that is, a material that is transparent to light in the visible region. For example, as the base material 12, a synthetic quartz substrate or a film made of a resin such as polyethylene terephthalate (PET) is used. From the viewpoint of increasing the flexibility of the color-developing structure 10, the base material 12 is preferably a resin film. The film thickness of the base material 12 is, for example, 10 μm or more and 100 μm or less.

The resin layer 13 has an uneven structure on the surface which is the surface opposite to the surface in contact with the base material 12. The uneven structure of the resin layer 13 includes a plurality of irregularly arranged convex portions. The resin layer 13 is composed of a resin that transmits light in the entire visible region, that is, a resin that is transparent to light in the visible region. As the resin of the material of the resin layer 13, for example, a thermosetting resin or a photocurable resin is used.

The dielectric layer 14 covers the surface of the resin layer 13 and has a surface having a shape that follows the uneven structure of the resin layer 13. The dielectric layer 14 is a layer made of a single-layer thin film composed of a dielectric, and emits reflected light enhanced by interference. The dielectric layer 14 is composed of any material of metal oxide, metal nitride, and metal oxynitride. In order to preferably cause light interference in the dielectric layer 14, the refractive index of the material of the dielectric layer 14 is preferably larger than 1.5 and 3.0 or less, and the dielectric layer 14 has a refractive index of 3.0 or less. The film thickness is preferably 10 nm or more and 10 μm or less. The material and film thickness of the dielectric layer 14 may be selected according to the desired color to be developed by the color-developing structure 10.

The reflective layer 15 is on the opposite side of the dielectric layer 14 from the resin layer 13 and is in contact with the dielectric layer 14. That is, the dielectric layer 14 is sandwiched between the resin layer 13 and the reflective layer 15. The reflective layer 15 has a surface having a shape that follows the uneven structure of the surface of the dielectric layer 14. The reflective layer 15 has a function of increasing the intensity of the reflected light that is strengthened and emitted by interference. The material and film thickness of the reflective layer 15 are not limited as long as the reflective layer 15 having a higher reflectance than the transmittance in the visible region can be realized. However, in order to further increase the intensity of the reflected light, the reflective layer 15 is made of a metal material. The thickness of the reflective layer 15 is preferably 50 nm or more.

The color-developing structure 10 of the first embodiment uses light entering the color-developing structure 10 from the side where the base material 12 is located with respect to the resin layer 13 as incident light, and the side where the base material 12 is located with respect to the resin layer 13. Observed from. In other words, the color-developing structure 10 is observed from the side where the resin layer 13 is located with respect to the dielectric layer 14.

When the incident light transmitted through the base material 12 and the resin layer 13 enters the dielectric layer 14, the dielectric layer 14 emits reflected light due to thin film interference. That is, the light reflected at the interface between the dielectric layer 14 and the resin layer 13 and the light reflected at the interface between the dielectric layer 14 and the reflective layer 15 cause interference, and light in the enhanced wavelength range is emitted. NS. Since the reflective layer 15 is located on the opposite side of the dielectric layer 14 from the resin layer 13, the intensity of the reflected light emitted toward the observer is higher than that in the case where the reflective layer 15 is not provided. Becomes larger. Then, the reflected light enhanced by the interference is scattered by the irregular unevenness of the resin layer 13 and emitted in multiple directions, so that the color change depending on the observation angle becomes gentle.

In order to increase the intensity of the reflected light, the reflectance of light at the interface between the dielectric layer 14 and the reflective layer 15, that is, the reflectance of light transmitted through the dielectric layer 14 in the reflective layer 15 is 30% or more. It is preferable to have.

The refractive index of the material of the dielectric layer 14 is n1, the refractive index of the material of the resin layer 13 is n2, and the refractive index of the material of the reflective layer 15 is n3. When n1> n2 and n1> n3, the following equation (1) is satisfied for wavelengths in the visible region that are strengthened by interference. In the following equation (1), d is the film thickness of the dielectric layer 14, m is 0 or an arbitrary positive integer, θ is the incident angle of the incident light, and λ is the wavelength of the incident light.

2 × n1 × d × cos θ = (1/2 + m) λ ・ ・ ・ (1)
Further, when n1> n2 and n1 <n3, the following equation (2) is satisfied for the wavelengths in the visible region that are strengthened by interference. In the following equation (2), d is the film thickness of the dielectric layer 14, m is an arbitrary positive integer, θ is the incident angle of the incident light, and λ is the wavelength of the incident light.

2 × n1 × d × cos θ = m × λ ・ ・ ・ (2)
When the above formula (1) or (2) is satisfied, the reflected light enhanced by thin film interference is preferably obtained.

Here, in general, the dielectric layer for causing single-layer thin film interference or multilayer film interference is a material that transmits light in the entire visible region in order to increase the reflection component, that is, light in the entire visible region. Consists of transparent material. However, the wavelength range of the reflected light due to the single layer thin film interference does not have a steep peak as the wavelength range of the reflected light due to the multilayer film interference. Therefore, the wavelength selectivity of the reflected light tends to be low, and as a result, the sharpness of the color visually recognized as the reflected light tends to be low. That is, the conventional dielectric layer that causes thin film interference of a single layer is not suitable for use in a structure for developing a specific color.

Therefore, in the present embodiment, the dielectric layer 14 absorbs at least a part of the light in the visible region other than the dominant color of the reflected light in the dielectric layer 14. The dominant color of the reflected light is a color corresponding to the wavelength range in which the intensity of the reflected light is the highest as a result of light interference. The dominant color is visually recognized in the color-developing structure 10.

Specifically, in the visible region, the extinction coefficient k of the material of the dielectric layer 14 has the smallest value in the wavelength range of the dominant color of the reflected light and is the largest in the wavelength range other than the dominant color. Has a value. For example, in the wavelength range of the dominant color of the reflected light, the extinction coefficient k of the material of the dielectric layer 14 is 0, and the farther away from the wavelength range, the larger the extinction coefficient k of the material.

Such a dielectric layer 14 can be realized by using a metal oxide, a metal nitride, or a metal oxynitride having a composition in which a metal element is excessive than the stoichiometric composition as the material thereof. These metal compounds, when having a stoichiometric composition, transmit light over the entire visible region. Then, the minimum value of the extinction coefficient k of the metal compound tends to shift to the lower wavelength side as the amount of the metal element becomes excessive. The extinction coefficient k of the metal increases as the wavelength increases.

According to the color-developing structure 10 of the present embodiment, at least a part of the light in the visible region other than the dominant color of the reflected light of the dielectric layer 14 is absorbed by the dielectric layer 14. Therefore, among the incident light, light other than the dominant color of the reflected light, that is, light having a color different from the color desired to be developed by the color-developing structure 10, is reflected by the color-developing structure 10 and visually recognized by the observer. Is suppressed. Therefore, the specific color to be developed by the color-developing structure 10 can be visually recognized more clearly.

[Concave and convex structure]
The details of the uneven structure of the resin layer 13 will be described. As the uneven structure, any of the two structures, the first structure and the second structure, can be applied, and each of these two structures will be described. FIG. 1 shows a color-developing structure 10A which is a color-developing structure 10 having a concavo-convex structure of the first structure. The concave-convex structure of the first structure includes a plurality of convex portions 13a and a concave portion 13b which is a region between the plurality of convex portions 13a.

<First structure>
The details of the uneven structure of the first structure will be described with reference to FIGS. 2A and 2B. FIG. 2A is a plan view of the resin layer 13 as viewed from a viewpoint facing the surface thereof, and FIG. 2B is a cross-sectional view of the resin layer 13 along the line II-II of FIG. 2A. In FIG. 2A, dots are added to the convex portion 13a of the concave-convex structure.

As shown in FIG. 2A, the first direction Dx and the second direction Dy are directions included in a plane along the spreading direction of the resin layer 13, and the first direction Dx and the second direction Dy are orthogonal to each other. The plane is a plane orthogonal to the thickness direction of the resin layer 13.

When the resin layer 13 is viewed from the viewpoint facing the surface thereof, the pattern formed by the convex portion 13a is a pattern composed of a set of a plurality of rectangles R indicated by broken lines. The rectangle R is an example of a graphic element. Each rectangle R has a shape extending in the second direction Dy, and in each rectangle R, the length d2 of the second direction Dy has a size equal to or larger than the length d1 of the first direction Dx. The plurality of rectangles R are arranged so as not to overlap in either the first direction Dx and the second direction Dy.

In the plurality of rectangles R, the length d1 of the first direction Dx is constant. The arrangement interval of the plurality of rectangles R in the first direction Dx is d1, that is, the plurality of rectangles R are arranged in the first direction Dx with a period of d1.

On the other hand, in the plurality of rectangles R, the length d2 of the second direction Dy is irregular, and the length d2 in each rectangle R is a value selected from the population having a predetermined standard deviation. This population preferably follows a normal distribution. In the pattern consisting of a plurality of rectangles R, for example, a plurality of rectangles R having a length d2 distributed with a predetermined standard deviation are tentatively spread in a predetermined area, and the presence or absence of the actual arrangement of each rectangle R is determined according to a certain probability. By determining, it is formed by setting the area where the rectangle R is arranged and the area where the rectangle R is not arranged. In order to efficiently scatter the reflected light from the dielectric layer 14, the length d2 preferably has a distribution having an average value of 4.13 μm or less and a standard deviation of 1 μm or less.

The area where the rectangle R is arranged is the area where the convex portion 13a is arranged, and when the rectangles R adjacent to each other are in contact with each other, one area where the areas where the rectangle R is arranged is combined is 1 Two convex portions 13a are arranged. In this case, the length of the convex portion 13a in the first direction Dx is an integral multiple of the length d1 of the rectangle R.

In order to suppress the occurrence of iridescent spectroscopy due to unevenness, the length d1 of the first direction Dx in the rectangle R is set to be equal to or less than the wavelength of light in the visible region. In other words, the length d1 has a length of less than or equal to the sub-wavelength, that is, less than or equal to the wavelength range of the incident light. That is, the length d1 is preferably 830 nm or less, and more preferably 700 nm or less. Further, the length d1 is preferably smaller than the wavelength range of the dominant color of the reflected light in the dielectric layer 14. For example, when the color-developing structure 10 develops a blue color, the length d1 is preferably about 300 nm, and when the color-developing structure 10 develops a green color, the length d1 is about 400 nm. Preferably, when the color-developing structure 10 develops a red color, the length d1 is preferably about 460 nm.

In order to increase the spread of the reflected light from the dielectric layer 14, that is, to enhance the scattering effect of the reflected light, it is preferable that the uneven structure has many undulations, and it is viewed from the viewpoint facing the surface of the resin layer 13. The ratio of the area occupied by the convex portion 13a per unit area is preferably 40% or more and 60% or less. For example, when viewed from the viewpoint facing the surface of the resin layer 13, the ratio of the area of the convex portion 13a to the area of the concave portion 13b per unit area is preferably 1: 1.

As shown in FIG. 2B, the height h1 of the convex portion 13a is constant, and the convex portion 13a has one step from the plane on which the base portion of the convex portion 13a is located. The height h1 of the convex portion 13a may be set according to a desired color to be developed by the color-developing structure 10, that is, a wavelength range desired to be reflected from the color-developing structure 10. If the height h1 of the convex portion 13a is larger than the surface roughness of the dielectric layer 14 on the convex portion 13a or the concave portion 13b, the scattering effect of the reflected light can be obtained.

However, in order to suppress light interference caused by reflection on unevenness, the height h1 is preferably 1/2 or less of the wavelength of light in the visible region, that is, 413 nm or less. Further, in order to suppress the interference of the light, the height h1 is more preferably 1/2 or less of the wavelength range of the dominant color of the reflected light in the dielectric layer 14.

Further, if the height h1 is excessively large, the scattering effect of the reflected light due to the unevenness becomes too high, and the intensity of the reflected light tends to be low. Therefore, the height h1 is preferably 10 nm or more and 200 nm or less. For example, in the color-developing structure 10 exhibiting blue color, in order to obtain an effective spread of light, the height h1 is preferably about 40 nm or more and 130 nm or less, and in order to prevent the scattering effect from becoming too high. The height h1 is preferably 100 nm or less.

Note that the rectangles R may form the pattern of the convex portion 13a by arranging the two rectangles R arranged along the first direction Dx so as to overlap each other. That is, the plurality of rectangles R may be arranged in the first direction Dx at an arrangement interval smaller than the length d1, and the arrangement intervals of the rectangles R may not be constant. In the portion where the rectangles R overlap, one convex portion 13a is located in one area in which the areas where the rectangles R are arranged are combined. In this case, the length of the convex portion 13a in the first direction Dx is different from the integral multiple of the length d1 of the rectangle R. Further, the length d1 of the rectangle R does not have to be constant, and in each rectangle R, the length d2 is the length d1 or more, and the standard deviation of the length d2 in the plurality of rectangles R is the length d1. It should be larger than the standard deviation. In this case as well, the effect of scattering the reflected light can be obtained.

<Second structure>
FIG. 3 shows a color-developing structure 10B which is a color-developing structure 10 having a concavo-convex structure having a second structure. The form in which the resin layer 13 has the concavo-convex structure of the first structure and the form in which the resin layer 13 has the concavo-convex structure of the second structure are common except for the configuration of the concavo-convex structure in the color-developing structure 10.

In the convex portion 13c of the concave-convex structure of the second structure, the first convex portion element similar to the convex portion 13a of the first structure and the second convex portion element extending in a band shape are formed in the thickness direction of the resin layer 13. It has a superposed structure.
According to the color-developing structure 10A having the uneven structure of the first structure, the change depending on the observation angle of the color visually recognized by the scattering effect of the reflected light becomes gradual, but the decrease in the intensity of the reflected light due to the scattering causes. The vividness of the visible color is reduced. Depending on the application of the color-developing structure 10, a sheet capable of observing more vivid colors from a wide observation angle may be required. The second convex element in the second structure is arranged so that the incident light is strongly diffracted in a specific direction, and the light scattering effect based on the first convex element and the light based on the second convex element. Due to the diffraction effect of, a color-developing structure 10B capable of observing more vivid colors from a wide observation angle is realized.

The second convex element will be described with reference to FIGS. 4A and 4B. FIG. 4A is a plan view of a concavo-convex structure composed of only the second convex element, and FIG. 4B is a cross-sectional view taken along the line IV-IV of FIG. 4A. In FIG. 4A, the second convex element is indicated by a dot.

As shown in FIG. 4A, in a plan view, the second convex element 13Eb has a band shape extending with a constant width along the second direction Dy, and the plurality of second convex elements 13Eb have the first direction Dx. They are lined up at intervals along. In other words, the pattern formed by the second convex element 13Eb is a pattern consisting of a plurality of strip-shaped regions extending along the second direction Dy and lining up along the first direction Dx. The length d3 of the first direction Dx in the second convex element 13Eb may be the same as or different from the length d1 of the rectangle R that determines the pattern of the first convex element.

The arrangement interval de of the second convex element 13Eb in the first direction Dx, that is, the arrangement interval of the band-shaped region in the first direction Dx is such that at least a part of the reflected light on the surface of the uneven structure of the second convex element 13Eb , Set to be observed as primary diffracted light. The primary diffracted light is, in other words, diffracted light having a diffraction order m of 1 or -1. That is, when the incident angle of the incident light is θ, the reflection angle of the reflected light is φ, and the wavelength of the diffracted light is λ, the arrangement interval de satisfies de ≧ λ / (sinθ + sinφ). For example, when targeting visible light having λ = 360 nm, the arrangement interval de of the second convex element 13Eb may be 180 nm or more, that is, the arrangement interval de is the minimum wavelength in the wavelength range included in the incident light. It may be 1/2 or more of. The arrangement interval de is a distance along the first direction Dx between the ends of the two second convex element 13Eb adjacent to each other, and is the same as the second convex element 13Eb in the first direction Dx. The distance between the ends located on the side of.

The periodicity of the pattern formed by the second convex element 13Eb is reflected in the periodicity of the uneven structure of the resin layer 13. When the arrangement spacing de of the plurality of second convex elements 13Eb is constant, the reflected light of a specific wavelength is emitted from the dielectric layer 14 at a specific angle due to the diffraction phenomenon on the outermost surface of the dielectric layer 14. NS. Since the reflection intensity of light due to this diffraction is very strong as compared with the reflection intensity of the reflected light generated by the light scattering effect based on the first convex element, light having a brilliance like metallic luster is visually recognized. On the other hand, spectroscopy occurs due to diffraction, and the visually recognized color changes according to the change in the observation angle.

Therefore, for example, even if the structures of the dielectric layer 14 and the first convex element are designed so that the colored structure 10 exhibiting blue color can be obtained, the arrangement spacing de of the second convex element 13Eb is about 400 nm to 5 μm. Assuming a constant value of, strong green to red light due to diffraction is observed depending on the observation angle. On the other hand, for example, when the arrangement interval de of the second convex element 13Eb is increased to about 50 μm, the range of the angle at which the light in the visible region is diffracted becomes narrow, so that the color change due to the diffraction is difficult to see. However, light with a brilliance such as metallic luster is observed only at a specific observation angle.

Therefore, if the arrangement interval de is not set to a constant value and the pattern of the second convex element 13Eb is a pattern in which a plurality of periodic structures having different periods are superimposed, light of a plurality of wavelengths is added to the reflected light due to diffraction. Since they are mixed, it is difficult to visually recognize the dispersed and highly monochromatic light. Therefore, a glossy and vivid color is observed at a wide observation angle. In this case, the arrangement spacing de is selected from, for example, a range of 360 nm or more and 5 μm or less, and the average value of the arrangement spacing de of the plurality of second convex elements 13Eb is 1 / of the minimum wavelength in the wavelength range included in the incident light. It may be 2 or more.

However, as the standard deviation of the arrangement interval de increases, the arrangement of the second convex element 13Eb becomes irregular and the scattering effect becomes dominant, making it difficult to obtain strong reflection due to diffraction. Therefore, the arrangement interval de of the second convex element 13Eb is such that the reflected light due to diffraction is in the same range as the range in which the light spreads, depending on the angle at which the light spreads due to the light scattering effect based on the first convex element. It is preferable to determine that it is emitted. For example, when the reflected blue light is emitted in a range of ± 40 ° with respect to the incident angle, the array spacing de is set to an average value of 1 μm or more and 5 μm or less in the pattern of the second convex element 13Eb. The standard deviation is set to about 1 μm. As a result, the reflected light due to diffraction is generated at an angle similar to the angle at which the light spreads due to the light scattering effect based on the first convex element.

That is, the concave-convex structure based on the plurality of second convex element 13Eb is different from the structure for diffracting and extracting light in a specific wavelength range, and by dispersing the arrangement interval de, a predetermined angular range is used by using diffraction. It is a structure for emitting light in various wavelength ranges.

Further, in order to generate a diffraction phenomenon having a longer period, a square region having a side of 10 μm or more and 100 μm or less is set as a unit region, and in the pattern of the second convex element 13Eb for each unit region, the array spacing de is set to the average value. It may be about 1 μm or more and 5 μm or less, and the standard deviation may be about 1 μm. The plurality of unit regions may include regions in which the sequence spacing de is a constant value included in the range of 1 μm or more and 5 μm or less. Even if there is a unit region in which the sequence spacing de is constant, if the sequence spacing de has a variation of about 1 μm in any of the unit regions adjacent to this unit region, the resolution of the human eye. In, the same effect as when the sequence spacing de has variation in all unit regions can be expected.

Note that the second convex element 13Eb shown in FIGS. 4A and 4B has periodicity due to the arrangement interval de only in the first direction Dx. The light scattering effect based on the first convex element mainly acts on the reflected light in the direction along the first direction Dx in the plan view of the color-developing structure 10, but the direction along the second direction Dy. It can also partially affect the reflected light to. Therefore, the second convex element 13Eb may also have periodicity in the second direction Dy. That is, the pattern of the second convex element 13Eb may be a pattern in which a plurality of strip-shaped regions extending in the second direction Dy are arranged along each of the first direction Dx and the second direction Dy.

In such a pattern of the second convex element 13Eb, for example, the average value of each of the arrangement interval along the first direction Dx and the arrangement interval along the second direction Dy of the strip-shaped region is 1 μm or more and 100 μm or less. It suffices to have some variation. Further, according to the difference between the influence of the light scattering effect based on the first convex element on the first direction Dx and the influence on the second direction Dy, the average value of the array spacing along the first direction Dx and the average value. The average value of the sequence spacing along the second direction Dy may be different from each other, and the standard deviation of the sequence spacing along the first direction Dx and the standard deviation of the sequence spacing along the second direction Dy are mutually exclusive. It may be different.

As shown in FIG. 4B, the height h2 of the second convex element 13Eb may be larger than the surface roughness of the dielectric layer 14 on the convex portion 13c and the concave portion 13b. However, as the height h2 increases, the diffraction effect based on the second convex element 13Eb becomes dominant in the effect of the uneven structure on the reflected light, and it becomes difficult to obtain the light scattering effect based on the first convex element. Therefore, the height h2 is preferably about the same as the height h1 of the first convex element, and the height h2 may coincide with the height h1. For example, the height h1 of the first convex element and the height h2 of the second convex element 13Eb are preferably included in the range of 10 nm or more and 200 nm or less. The height h1 of the 1-convex element and the height h2 of the 2nd convex element 13Eb are preferably included in the range of 10 nm or more and 130 nm or less.

The details of the uneven structure of the second structure will be described with reference to FIGS. 5A and 5B. FIG. 5A is a plan view of the resin layer 13 as viewed from a viewpoint facing the surface thereof, and FIG. 5B is a cross-sectional view of the resin layer 13 along the VV line of FIG. 5A. In FIG. 5A, dots having different densities are attached to the pattern formed by the first convex element and the pattern formed by the second convex element.

As shown in FIG. 5A, when the resin layer 13 is viewed from the viewpoint facing the surface thereof, the patterns formed by the convex portion 13c are the first pattern, which is the pattern formed by the first convex portion element 13Ea, and the second pattern. This is a pattern in which a second pattern, which is a pattern formed by the convex element 13Eb, is superimposed. That is, in the region where the convex portion 13c is located, the region S1 including only the first convex portion element 13Ea, the region S2 in which the first convex portion element 13Ea and the second convex portion element 13Eb overlap, and the second convex portion The region S3 including only the part element 13Eb is included. In FIG. 5A, the first convex element 13Ea and the second convex element 13Eb are overlapped so that their ends are aligned in the first direction Dx, but the end of the first convex element 13Ea. And may be off the end of the second convex element 13Eb.

As shown in FIG. 5B, in the region S1, the height of the convex portion 13c is the height h1 of the first convex portion element 13Ea. Further, in the region S2, the height of the convex portion 13c is the sum of the height h1 of the first convex portion element 13Ea and the height h2 of the second convex portion element 13Eb. Further, in the region S3, the height of the convex portion 13c is the height h2 of the second convex portion element 13Eb. As described above, in the convex portion 13c, the projected image of the resin layer 13 in the thickness direction forms the first pattern, the first convex portion element 13Ea having a predetermined height h1 and the projection in the thickness direction. The image forms a second pattern, and the second convex element 13Eb having a predetermined height h2 has a plurality of steps overlapped in the height direction. By the way, the convex portion 13c can be regarded as having the second convex element 13Eb laminated on the first convex element 13Ea from the base of the convex portion 13c, and the first convex portion on the second convex element 13Eb. It can also be considered that the elements 13Ea are stacked.

Even if the pattern formed by the first convex element 13Ea and the pattern formed by the second convex element 13Eb are arranged so that the first convex element 13Ea and the second convex element 13Eb do not overlap each other. good. Even with such a structure, the light scattering effect based on the first convex element 13Ea and the light diffraction effect based on the second convex element 13Eb can be obtained. However, if the first convex element 13Ea and the second convex element 13Eb are arranged so as not to overlap each other, the first convex element 13Ea can be arranged per unit area as compared with the first structure. Area becomes smaller and the light scattering effect is reduced. Therefore, in order to enhance the light scattering effect and the diffraction effect based on the convex elements 13Ea and 13Eb, as shown in FIGS. 5A and 5B, the first convex element 13Ea and the second convex element 13Eb are combined. It is preferable that the convex portions 13c have a shape having a plurality of steps.

[Characteristics of dielectric layer]
The characteristics of the dielectric layer 14 will be described with reference to simulation results. In the simulation, when the color-developing structure 10 is colored blue, titanium oxide (TiO ₂ ) having a stoichiometric composition is used as the material of the dielectric layer 14, and a metal element rather than the stoichiometric composition. The wavelength range of the reflected light was determined for each of the cases where excess titanium oxide (TiO _{x: 0 <x <2) was used.} In other words, _{TiO x} is titanium oxide in a state in which oxygen is deficient with respect _{to TiO 2.} Further, in the simulation, aluminum was applied to the material of the reflective layer 15.

First, FIGS. 6 to 8 show the refractive index n and the extinction coefficient k of the materials of the dielectric layer 14 and the reflective layer 15. 6 shows a refractive index n and extinction coefficient k of TiO _2, 7, oxygen show a refractive index n and extinction coefficient k of TiO _x was deposited to lack, 8, aluminum The refractive index n and the extinction coefficient k of FIG. 9 shows the refractive index n and the extinction coefficient k of polyethylene terephthalate used as the base material 12. Figures 6, 8 and 9 are standard values for commercially available products, and FIGS. 7 and 7 are actual measurement values.

As shown in FIG. 6, for TiO ₂ , the extinction coefficient k is 0 in _{the entire visible region, that is, TiO 2} transmits light in the entire visible region. On the other hand, as shown in FIG. 7, for TiO _x , the extinction coefficient k is 0 in the wavelength range of about 410 nm to about 450 nm, which is a part of the wavelength range of blue light, and the extinction coefficient k becomes 0 as the distance from the wavelength range increases. The decay coefficient k is increasing. For example, the extinction coefficient k in the wavelength range of about 750 nm or more is around 0.05. As described above, in titanium oxide having an excess of metal elements than the stoichiometric composition, the extinction coefficient k is the smallest in the wavelength range of blue light, and in the wavelength range other than blue light, it is higher than the wavelength range of blue light. Is also big. The extinction coefficient k becomes maximum in the wavelength region of red light in the visible region. As shown in FIGS. 6 and 7, there is no difference in the refractive index n between _{TiO 2} and TiO _x.

For each of TiO ₂ and TiO _x , the incident angle of the incident light is 30 °, the thickness of the reflective layer 15 is 0.1 μm, and the dominant color of the reflected light from the laminate of the dielectric layer 14 and the reflective layer 15. The optimum film thickness in which is blue was searched for using a genetic algorithm. _{As a result, the film thickness of TiO 2} suitable for blue color development was 0.0682 μm, and the film thickness of _{TiO x suitable for blue color development was 0.0624 μm.}

_{When each of TiO 2} and TiO _x is used as the material of the dielectric layer 14, the film thickness of the dielectric layer 14 is set to a film thickness suitable for the blue color development, and the film thickness of the reflective layer 15 is set to 0.1 μm. , The wavelength range of the reflected light from the laminate of the dielectric layer 14 and the reflective layer 15 was determined. FIG. 10 shows the result. Note that FIG. 10 shows the wavelength range of the reflected light in the blue-colored multilayer film layer as a reference value. This multilayer film layer is an alternating laminate _{of a TiO 2} thin film and a SiO _{2 thin film.}

As shown in FIG. 10, when the dielectric layer 14 composed of a single-layer thin film is used, it corresponds to a wavelength range other than blue light, that is, a color different from the dominant color, as compared with the case where a multilayer film layer is used. It can be seen that the intensity of the reflected light in the wavelength range is high. However, comparing the case _{where TiO 2} is used as the material of the dielectric layer 14 and the case where dio _x is used, the intensity of the reflected light in the wavelength range other than blue light is higher in the case where _{TiO x is used.} Is low. This is because, as described above, the extinction coefficient k of _{TiO x} is larger than the extinction coefficient _{k of TiO 2 in the wavelength range other than blue light.} That is, the _{dielectric layer 14 made of TiO x} has an absorbency of light other than blue light, and as a result, as compared with the case where _{TiO 2 having no absorbency in the entire visible region is used,} The intensity of the reflected light in the wavelength region other than the blue light, in other words, the intensity of the reflected light in the long wavelength region is lower than that in the wavelength region of the blue light.

Therefore, when the dielectric layer 14 made of a single-layer thin film is used, the amount of light of a color other than blue contained in the reflected light is less when _{TiO x is used than when TiO 2} is used. As a result, the reflected blue light is easily visible. In other words, a brighter blue color is observed.

When TiO ₂ and TiO _x are used, the film thickness of the dielectric layer 14 is unified to the film thickness of _{TiO 2 suitable for blue color development, and the TiO x} film suitable for blue color development. Similar results were obtained in all cases where the thickness was unified. That is, when TiO _x was used, the intensity of the reflected light in the wavelength range other than blue light was lower.

[Manufacturing method of colored structure]
The method for manufacturing the color-developing structure 10 will be described.
First, the resin layer 13 is formed on the base material 12. As a method for forming the uneven structure of the resin layer 13, for example, a nanoimprint method is used. For example, when the concave-convex structure of the resin layer 13 is formed by the optical nanoimprint method, first, the material of the resin layer 13 is included in the surface on which the unevenness of the mold, which is an intaglio having the inverted unevenness of the unevenness to be formed, is formed. The coating liquid is applied. As the material of the resin layer 13, a resin having photocurability is used. The coating method of the coating liquid is not particularly limited, and known coating methods such as an inkjet method, a spray method, a bar coating method, a roll coating method, a slit coating method, and a gravure coating method may be used.

Next, the base material 12 is superposed on the surface of the layer made of the coating liquid, and light is irradiated from the base material 12 side or the mold side in a state where the base material 12 and the mold are pressed against each other. Subsequently, the mold is released from the layer made of the cured resin and the base material 12. As a result, the unevenness of the mold is transferred to the resin to form the resin layer 13 having the unevenness on the surface, and a laminate composed of the base material 12 and the resin layer 13 is formed. The mold is made of, for example, synthetic quartz or silicon, and is formed by using known microfabrication techniques such as lithography and dry etching for irradiating light or charged particle beams.

The coating liquid may be applied to the surface of the base material 12 and irradiated with light in a state where the mold is pressed against the layer made of the coating liquid on the base material 12. Further, the thermal nanoimprint method may be used instead of the optical nanoimprint method.

Subsequently, the dielectric layer 14 is formed on the uneven surface of the resin layer 13. Further, the reflective layer 15 is formed on the surface of the dielectric layer 14. The dielectric layer 14 and the reflective layer 15 are formed by a known thin film forming technique such as sputtering or vacuum vapor deposition, depending on the material. As a result, the color-developing structure 10 is formed.

By adjusting the amount of the material introduced during the film formation of the dielectric layer 14, it is possible to produce a metal compound having a composition in which the metal element is excessive compared to the stoichiometric composition. For example, when the dielectric layer 14 made of a metal oxide is formed, the oxygen flow rate is reduced as compared with the case of forming a thin film having a stoichiometric composition, so that the dielectric layer 14 having an excess composition of metal elements can be formed.

Since the color-developing structure 10 of the present embodiment includes a dielectric layer 14 made of a single thin film as a layer that causes interference, the structure thereof is compared with a structure that has a multilayer film layer as a layer that causes interference. Is simple, and the number of thin films required is small. Further, as compared with the structure including the multilayer film layer, the influence of the manufacturing error of the film thickness of one thin film on the color development of the color development structure 10 is small. Therefore, the load required for manufacturing the color-developing structure 10 can be reduced, and the desired color can be easily obtained.

As described above, according to the first embodiment, the following advantages can be obtained.
(1) Since the dielectric layer 14 that causes interference is a single-layer thin film, the structure of the color-developing structure 10 is simplified as compared with the case where a multilayer film layer is used. Therefore, in the color-developing structure 10 in which the color change due to the change in the observation angle is suppressed due to the light scattering effect due to the irregular unevenness, the load required for its manufacture is reduced.

(2) Since the dielectric layer 14 has absorption of light other than the dominant color of the reflected light in the visible region, the light in the wavelength range having this absorption is included in the reflected light from the color-developing structure 10. Is suppressed. Therefore, the sharpness of the dominant color exhibited by the color-developing structure 10 is enhanced.

Specifically, the extinction coefficient k of the material of the dielectric layer 14 in the visible region has the smallest value in the wavelength range of the dominant color of the reflected light in the dielectric layer 14, and is other than the wavelength range of the dominant color. Has the largest value in. Further, the dielectric layer 14 is composed of a metal compound of any one of a metal oxide, a metal nitride, and a metal oxynitride, and the metal compound has a composition in which a metal element is excessive more than a chemical quantitative composition. .. With these, the above-mentioned effect can be obtained.

(3) The color-developing structure 10 includes a reflective layer 15 located on the opposite side of the resin layer 13 with respect to the dielectric layer 14. As a result, the intensity of the reflected light is increased in the color-developing structure 10 observed from the side where the resin layer 13 is located with respect to the dielectric layer 14. Therefore, the visibility of the color exhibited by the color-developing structure 10 is enhanced.

(4) The dielectric layer 14 has a thickness of 10 nm or more and 10 μm or less, and the refractive index of the material of the dielectric layer 14 is larger than 1.5 and 3.0 or less. Interference of light in No. 14 is preferably likely to occur.

(5) The reflectance of the light transmitted through the dielectric layer 14 in the reflective layer 15 is 30% or more, the reflective layer 15 is made of a metal material, and the reflective layer 15 has a thickness of 50 nm or more. Each of the possessions further enhances the intensity of the reflected light.

(6) In the form in which the resin layer 13 has a concavo-convex structure having a second structure, the concavo-convex structure provides a diffusion effect and a diffraction effect of reflected light. As a result, the reflected light enhanced by the interference, that is, the dominant color can be observed at a wide observation angle, and the intensity of the reflected light is increased, so that a vivid color with a glossy feeling is visually recognized.

(7) Since the concave-convex structure of the resin layer 13 is formed by using the imprint method, the resin layer 13 having fine irregularities can be preferably and easily formed. Further, when the color-developing structure 10 includes the base material 12 that supports the resin layer 13, the imprint method can be easily applied.

(Second Embodiment)
A second embodiment of the color-developing structure and the method for manufacturing the color-developing structure will be described with reference to FIG. In the second embodiment, the positional relationship between the dielectric layer and the reflective layer is different from that in the first embodiment. Hereinafter, the differences between the second embodiment and the first embodiment will be mainly described, and the same elements as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 11, in the color-developing structure 11 of the second embodiment, the reflective layer 15 is in contact with the resin layer 13, and the dielectric layer 14 is located on the opposite side of the reflective layer 15 from the resin layer 13. There is. That is, in the color-developing structure 11 of the second embodiment, the positions of the dielectric layer 14 and the reflective layer 15 with respect to the resin layer 13 are opposite to those of the first embodiment, and the resin layer 13 and the dielectric layer 14 The reflective layer 15 is sandwiched between the two. The dielectric layer 14 is the outermost layer of the color-developing structure 11 and is in contact with the air layer.

Also in the second embodiment, as the uneven structure of the resin layer 13, both the first structure and the second structure described in the first embodiment can be applied. FIG. 11 illustrates a form in which the resin layer 13 has a concavo-convex structure having a second structure. The base material 12 and the resin layer 13 in the second embodiment are the same as those in the first embodiment.

The reflective layer 15 covers the surface of the resin layer 13 and has a surface having a shape that follows the uneven structure of the resin layer 13. The dielectric layer 14 has a surface having a shape following the uneven structure of the surface of the reflective layer 15, that is, having a surface having a shape following the uneven structure of the resin layer 13. The configuration other than the positional relationship between the dielectric layer 14 and the reflective layer 15, that is, the materials and properties of the dielectric layer 14 and the reflective layer 15 are the same as those in the first embodiment.

The method for producing the color-developing structure 11 is the same as that of the first embodiment, except that the order of formation of the dielectric layer 14 and the reflective layer 15 is opposite.
The color-developing structure 11 of the second embodiment uses light entering the color-developing structure 11 from the side opposite to the base material 12 with respect to the resin layer 13 as incident light, and is opposite to the base material 12 with respect to the resin layer 13, that is, , Observed from the side where the dielectric layer 14 is located with respect to the resin layer 13.

When light is incident on the dielectric layer 14, the dielectric layer 14 emits reflected light due to thin film interference. That is, the light reflected at the interface between the dielectric layer 14 and the air layer and the light reflected at the interface between the dielectric layer 14 and the reflective layer 15 cause interference, and light in the enhanced wavelength range is emitted. .. By locating the reflective layer 15 on the same side as the resin layer 13 with respect to the dielectric layer 14, the intensity of the reflected light emitted toward the observer is higher than that in the case where the reflective layer 15 is not provided. Becomes larger. Then, the reflected light enhanced by the interference is scattered by the irregular unevenness and emitted in multiple directions, so that the color change depending on the observation angle becomes gentle.

The refractive index of the material of the dielectric layer 14 is n1, the refractive index of air is n4, and the refractive index of the material of the reflective layer 15 is n3. When n1> n4 and n1> n3, the following equation (3) is satisfied for wavelengths in the visible region that are strengthened by interference. In the following equation (3), d is the film thickness of the dielectric layer 14, m is 0 or an arbitrary positive integer, θ is the incident angle of the incident light, and λ is the wavelength of the incident light.

2 × n1 × d × cos θ = (1/2 + m) λ ・ ・ ・ (3)
Further, when n4 <n1 <n3, the following equation (4) is satisfied for wavelengths in the visible region that are strengthened by interference. In the following equation (4), d is the film thickness of the dielectric layer 14, m is an arbitrary positive integer, θ is the incident angle of the incident light, and λ is the wavelength of the incident light.

2 × n1 × d × cos θ = m × λ ・ ・ ・ (4)
When the above formula (3) or (4) is satisfied, the reflected light enhanced by thin film interference is preferably obtained.

Also in the second embodiment, as the material of the dielectric layer 14, a metal oxide, a metal nitride, or a metal oxynitride having a composition in which a metal element is excessive compared to the stoichiometric composition is used. Then, in the visible region, the extinction coefficient k of the material of the dielectric layer 14 has the smallest value in the wavelength range of the dominant color of the reflected light in the dielectric layer 14, and is other than the wavelength range of the dominant color. Has the largest value.

Therefore, of the light in the visible region, at least a part of the light other than the dominant color of the reflected light in the dielectric layer 14 is absorbed by the dielectric layer 14. Therefore, among the incident light, light other than the dominant color of the reflected light, that is, light having a color different from the color desired to be developed by the color-developing structure 11, is reflected by the color-developing structure 11 and visually recognized by the observer. Since it is suppressed, the specific color to be developed by the color-developing structure 11 can be visually recognized more clearly.

As described above, according to the second embodiment, in addition to the advantages of (1), (2), (4) to (7) of the first embodiment, the following advantages can be obtained.
(8) The color-developing structure 11 includes a reflective layer 15 located between the dielectric layer 14 and the resin layer 13. As a result, the intensity of the reflected light is increased in the color-developing structure 11 observed from the side where the dielectric layer 14 is located with respect to the resin layer 13. Therefore, the visibility of the color exhibited by the color-developing structure 11 is enhanced.

[Modification example]
Each of the above embodiments can be modified and implemented as follows.
-The color-developing structure may include an absorbing layer instead of the reflective layer 15. The absorption layer is located deeper than the dielectric layer 14 when viewed from the observer. For example, when the color-developing structure is observed from the side where the dielectric layer 14 is located with respect to the resin layer 13, as shown in FIG. 12, the absorption layer 16 is the surface of the base material 12 opposite to the resin layer 13. Cover. The absorption layer 16 absorbs at least a part of the light in the visible region other than the dominant color of the reflected light in the dielectric layer 14. The absorption layer 16 is a black layer containing a black pigment or the like, and may absorb light in the entire visible region. Since the absorption layer is provided, light in a wavelength range different from the wavelength range of the dominant color of the reflected light in the dielectric layer 14 can be applied to the interface of each layer inside the color-developing structure and the color-developing structure and its outside. It is suppressed that it is reflected at the interface and emitted toward the observer. Therefore, the sharpness of the dominant color visually recognized in the coloring structure is enhanced.

When the color-developing structure is observed from the side where the dielectric layer 14 is located with respect to the resin layer 13, the position of the absorption layer 16 in FIG. 12 is replaced with the position between the resin layer 13 and the dielectric layer 14. That is, the reflective layer may be provided at a position of the base material 12 that covers the surface opposite to the resin layer 13. Even if light other than the dominant color is mixed with the light transmitted through the dielectric layer 14, the resin layer 13 and the base material 12 and reflected by the reflective layer, the dielectric layer 14 absorbs light other than the dominant color. Therefore, it is possible to prevent light other than the dominant color from being emitted toward the observer. As a result, the reflective layer contributes to further increasing the intensity of the dominant color light in the reflected light.

The color-developing structure is a layer different from the layers described in the above embodiments and modifications, such as a protective layer forming the outermost part of the color-developing structure on the side opposite to the base material 12, and a layer having an ultraviolet absorbing function. You may also have more.

An uneven structure may be formed on the base material 12, and the base material 12 may function as an uneven layer. That is, a functional layer such as a dielectric layer 14 or a reflective layer 15 may be laminated on the surface of the base material 12 having a concavo-convex structure. In this case, the uneven structure is formed by using, for example, a dry etching method.

The figure forming the pattern formed by the convex portion 13a in the first structure of the concave-convex structure in the concave-convex layer and the pattern formed by the first convex portion element 13Ea in the second structure are not limited to rectangles. .. The graphic forming these patterns may be an oval or the like, and in short, it may be a graphic element having a shape in which the length along the second direction Dy is equal to or greater than the length along the first direction Dx. Just do it. Then, it is sufficient that the length d1 of the first direction Dx and the length d2 of the second direction Dy in the graphic element satisfy various conditions described in the description of the first structure.

-The width of the convex portion of the concave-convex structure of the concave-convex layer may gradually decrease from the base to the top in the first direction Dx. In this case, the dielectric layer 14 and the reflective layer 15 are likely to be formed on the convex portion. In this case, the length d1 and the length d3 of the first direction Dx are defined by the pattern formed by the bottom surface of the convex portion.

・ The use of the color-developing structure is not particularly limited. The colored structure may be attached to the article for decoration or may be attached to the article to prevent counterfeiting. Further, in each application, the color-developing structure may be applied to a sealing member and attached to an article, or may be applied to a transfer sheet and transferred to an article.

[Example]
The above-mentioned color-developing structure and a method for producing the same will be described with reference to specific examples. The color-developing structure of this embodiment has a structure corresponding to the first embodiment.

First, a mold was formed to form a concavo-convex structure using the optical imprint method. Since light having a wavelength of 365 nm is used as the light to be irradiated in the optical nanoimprint method, synthetic quartz that transmits light of this wavelength was used as the material for the mold. A mold was formed by forming the inverted unevenness of the unevenness to be formed on the resin layer on the synthetic quartz substrate by electron beam drawing and dry etching. The concavo-convex structure to be formed is the concavo-convex structure of the second structure. Optool HD-1100 (manufactured by Daikin Industries, Ltd.) was applied as a mold release agent to the surface of the mold.

Next, a photocurable resin is applied onto a PET film that has been easily adhered to one side, and the surface on which the unevenness of the mold is formed is pressed against this resin to irradiate the resin with light having a wavelength of 365 nm. Was cured. Then, the cured resin and PET film were peeled off from the mold. As a result, a laminate of a resin layer having an uneven structure and a PET film as a base material was obtained.

Subsequently, a single titanium oxide film having a film thickness of 60 nm was formed as a dielectric layer on the uneven surface of the obtained laminate of the resin layer and the base material by a sputtering method. At this time, by adjusting the flow rate of oxygen introduced into the chamber, a titanium oxide film was formed so that the amount of metal elements exceeded the stoichiometric composition. Further, a single aluminum film having a film thickness of 100 nm was formed as a reflective layer on the upper surface of the dielectric layer by a sputtering method.

As a result, the colored structure of the example was obtained. The colored structure of the example was observed from the side where the resin layer is located with respect to the dielectric layer. As a result of observing from a direction inclined by 30 ° with respect to the direction orthogonal to the surface of the base material, a glossy blue color was confirmed with good visibility.

Furthermore, the angle dependence of the reflected light emitted to the side where the resin layer is located with respect to the dielectric layer was measured. As a result of injecting white light into the color-developing structure at an incident angle of 30 °, scattered light was confirmed within a range of ± 30 ° with respect to the specularly reflected light.

Claims (14)

1. A concavo-convex layer having a concavo-convex structure including a flat surface and a convex portion located on the flat surface,
   It has a surface having a shape that follows the uneven structure, and includes a dielectric layer made of a single thin film that emits reflected light enhanced by interference.
   The convex portion has one or more steps from the plane, and the convex portion has a first length of a sub-wavelength or less along the first direction when viewed from a viewpoint facing the surface of the concave-convex layer. It is arranged so as to form a pattern including a set of a plurality of graphic elements each having a second length equal to or greater than the first length along a second direction orthogonal to the first direction. ,
   In the plurality of graphic elements, the standard deviation of the second length is larger than the standard deviation of the first length.
   The extinction coefficient of the material of the dielectric layer in the visible region has the smallest value in the wavelength range of the dominant color in the reflected light, and has the largest value in the wavelength range other than the dominant color. body.
2. A concavo-convex layer having a concavo-convex structure including a flat surface and a convex portion located on the flat surface,
   It has a surface having a shape that follows the uneven structure, and includes a dielectric layer made of a single thin film that emits reflected light enhanced by interference.
   The convex portion has one or more steps from the plane, and the convex portion has a first length of a sub-wavelength or less along the first direction when viewed from a viewpoint facing the surface of the concave-convex layer. It is arranged so as to form a pattern including a set of a plurality of graphic elements each having a second length equal to or greater than the first length along a second direction orthogonal to the first direction. ,
   In the plurality of graphic elements, the standard deviation of the second length is larger than the standard deviation of the first length.
   The dielectric layer is composed of a metal compound of any one of a metal oxide, a metal nitride, and a metal oxynitride, and the metal compound has a color-developing structure in which a metal element is excessive in composition rather than a chemical quantitative composition. body.
3. The color-developing structure according to claim 1 or 2, wherein the dielectric layer is made of titanium oxide, and the titanium oxide contains more titanium than the stoichiometric composition.
4. The dielectric layer is in contact with the uneven layer and
   The color-developing structure is
   The color-developing structure according to any one of claims 1 to 3, further comprising a reflective layer located on the opposite side of the dielectric layer to the concave-convex layer and having a function of enhancing the intensity of the reflected light.
5. The color-developing structure according to any one of claims 1 to 3, further comprising a reflective layer located between the uneven layer and the dielectric layer and having a function of enhancing the intensity of the reflected light.
6. The color-developing structure according to any one of claims 1 to 5, wherein the dielectric layer has a thickness of 10 nm or more and 10 μm or less.
7. The color-developing structure according to any one of claims 1 to 6, wherein the refractive index of the material of the dielectric layer is larger than 1.5 and 3.0 or less.
8. The color-developing structure according to claim 4 or 5, wherein the reflectance of light transmitted through the dielectric layer in the reflective layer is 30% or more.
9. The color-developing structure according to any one of claims 4, 5 and 8, wherein the reflective layer is made of a metal material.
10. The color-developing structure according to any one of claims 4, 5, 8 and 9, wherein the reflective layer has a thickness of 50 nm or more.
11. The color-developing structure according to any one of claims 1 to 10, further comprising a base material that supports the uneven layer.
12. When viewed from a viewpoint facing the surface of the uneven layer, the convex portion has a first pattern composed of a set of the plurality of graphic elements and a plurality of extending along the second direction and arranging along the first direction. It is arranged so as to form a pattern in which the second pattern consisting of the strip-shaped region of the above is overlapped.
    In the second pattern, the spacing between the plurality of strip-shaped regions along the first direction is not constant, and the average value of the spacing in the plurality of strip-shaped regions is included in the incident light on the dielectric layer. It is more than 1/2 of the minimum wavelength in the wavelength range,
    The convex portion has a first height, and the projected image of the concave-convex layer in the thickness direction has a first convex portion element forming the first pattern and a second height. The invention according to any one of claims 1 to 11, wherein the projected image in the thickness direction has a plurality of steps in which the second convex element forming the second pattern is overlapped in the height direction. Coloring structure.
13. The process of forming an intaglio and
    A step of forming a resin layer having an uneven structure having a flat surface and a convex portion located on the flat surface on the base material by transferring the unevenness of the intaglio plate to the base material using an imprint method.
    A dielectric layer made of a single thin film that has a surface having a shape that follows the uneven structure and emits reflected light enhanced by interference, and the extinction coefficient in the visible region is the dominant color in the reflected light. The convex portion has one or more steps from the plane, including a step of forming from a material having the smallest value in the wavelength range of the above and having the largest value in the wavelength range other than the dominant color. However, when viewed from the viewpoint facing the surface of the resin layer, the convex portion is along a first length that is equal to or less than a sub-wavelength along the first direction and a second direction that is orthogonal to the first direction. It is arranged so as to form a pattern including a set of a plurality of graphic elements each having a second length equal to or greater than the first length, and the plurality of graphic elements have the second length. A method for manufacturing a color-developing structure in which the standard deviation is larger than the standard deviation of the first length.
14. The process of forming an intaglio and
    A step of forming a resin layer having an uneven structure having a flat surface and a convex portion located on the flat surface on the base material by transferring the unevenness of the intaglio plate to the base material using an imprint method.
    A dielectric layer composed of a single-layer thin film having a surface having a shape following the uneven structure and emitting reflected light enhanced by interference is formed of a metal oxide, a metal nitride, and a metal oxynitride. The convex portion has one or more steps from the plane, including a step of forming the metal compound from the metal compound having a composition in which the metal element is excessive than the chemical quantitative composition, which is any of the metal compounds. When viewed from the viewpoint facing the surface of the resin layer, the convex portion has a first length that is equal to or less than a sub-wavelength along the first direction and the convex portion along the second direction orthogonal to the first direction. It is arranged so as to form a pattern including a set of a plurality of graphic elements each having a second length equal to or greater than the first length, and the standard of the second length in the plurality of graphic elements. A method for manufacturing a color-developing structure in which the deviation is larger than the standard deviation of the first length.

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