JP7326833B2 - Coloring structure, display, and method for producing coloring structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coloring structure exhibiting a structural color, a display body provided with the coloring structure, and a method for manufacturing the coloring structure.

Some organisms in the natural world have structural colors such as morpho butterflies. Structural colors observed in the natural world are different from colors that are visually observed due to electronic transitions in molecules, such as the colors exhibited by dyes. It is a color that is visually recognized by the action of an optical phenomenon.
Among the structural colors caused by light interference, for example, the structural color caused by multilayer interference is caused by the interference of the light reflected at each interface of the multilayer films in the multilayer films where the refractive indices of adjacent thin films are different from each other. Structural color. This multi-layer interference is one of the chromogenic principles of Morpho butterfly wings. In the morpho butterfly wing, in addition to multi-layer interference, light is scattered and diffracted by the fine irregularities on the surface of the wing.

As a structure for artificially reproducing the structural color of a morpho butterfly wing, there is a structure described in Patent Document 1. Patent Document 1 proposes a structure in which a multilayer film layer is laminated on the surface of a base material having fine irregularities arranged non-uniformly.
In a multilayer film, the wavelength of light intensified by interference changes depending on the optical path difference that occurs in each layer of the multilayer film, and the optical path difference is determined according to the film thickness and refractive index of each layer. The direction of emergence of the light intensified by interference is limited to a specific direction depending on the incident angle of the incident light. Therefore, in a structure in which multiple layers are laminated on a plane, the wavelength of reflected light that is visually recognized changes greatly depending on the viewing angle, and therefore the visually recognized color changes greatly depending on the viewing angle.

On the other hand, in the structure of Patent Document 1, since the multilayer film layers are laminated on the irregular unevenness, the reflected light strengthened by the interference spreads in multiple directions, so the color changes depending on the viewing angle. slow down. As a result, a structure that exhibits a specific color at a wide viewing angle like the wing of a morpho butterfly is realized.

JP-A-2005-153192

By the way, in the structure described in Patent Document 1, the multilayer film layer has unevenness following the unevenness of the base material, and this unevenness constitutes the surface of the structure. It takes time and cost to fabricate the uneven structure by processing the base material surface by techniques such as photolithography and etching. Therefore, in some cases, the concave-convex structure is produced by a nanoimprint method in which a mold is transferred onto a resin or the like on a base material.
When the structure produced in this way is deteriorated by being exposed to the outdoors for a long time, the uneven layer, the base material, etc. may turn yellow, and the hue of the structural color may change.

Although there are a number of methods for preventing the uneven structure from changing in hue, each method has drawbacks. For example, when an ultraviolet absorber is added to the concave-convex structure, problems such as migration due to bleed-out may occur. Further, when a dye is added to the concave-convex structure to make the hue change difficult to see, the hue may change due to the poor weather resistance of the dye. Furthermore, when inorganic particles are added to the concave-convex structure, the change in hue can be suppressed due to the surface scattering and light absorption properties of the particles, but there is a risk that the mold may be contaminated by falling off of the particles.

INDUSTRIAL APPLICABILITY The present invention provides a coloring structure capable of preventing hue change after long-term storage of the coloring structure and preventing contamination of the mold when producing the concave-convex structure, a display, and manufacturing of the coloring structure. The purpose is to provide a method.

To solve the problem, one embodiment of the present invention includes an uneven layer having an uneven structure on a surface, and a multilayer film layer provided on the uneven structure and having a surface shape that follows the uneven structure, Each layer constituting the film layer has a different refractive index between the layers adjacent to each other, and the reflectance of light in a specific wavelength region of the incident light incident on the multilayer film layer is different from that of light in other wavelength regions. A first direction set in advance and a second direction orthogonal to the first direction are a virtual plane on which the uneven structure is projected in the thickness direction of the uneven layer and the pattern formed by the projected image of the projection of the uneven structure on the virtual plane has a length along the second direction that is equal to or greater than a length along the first direction. a pattern comprising a set of graphic elements, each graphic element having a length along the first direction less than or equal to a sub-wavelength, each graphic element having a standard deviation of length along the second direction; It is larger than the standard deviation of the length along the first direction, and the uneven layer contains inorganic particles having a particle size of 23% or less of the line width in the first direction with respect to the solid content constituting the uneven layer. The gist is that it contains 3% by mass or more and 25% by mass or less.

Further, another aspect of the present invention includes a step of forming an uneven layer having an uneven structure on the surface by transferring the unevenness of an intaglio onto a resin using a nanoimprint method; forming each layer so that adjacent layers have different refractive indices, wherein a preset first direction and a second direction orthogonal to the first direction are set in the uneven layer A direction along a virtual plane, which is a virtual plane on which the uneven structure is projected in the thickness direction, and in the step of forming the uneven layer, a projected image of the convex portion constituting the uneven structure is projected on the virtual plane. The concave-convex structure is formed so as to include a pattern consisting of a set of a plurality of graphic elements whose length along the second direction is equal to or greater than the length along the first direction, and the graphic element is formed. The length along the first direction of is sub-wavelength or less, and the standard deviation of the length along the second direction of the graphic element is larger than the standard deviation of the length along the first direction. This is the gist of it.

According to the aspect of the present invention, it is possible to prevent the hue change after long-term storage of the coloring structure, and to prevent contamination of the mold when producing the concave-convex structure.

FIG. 2 is a cross-sectional view showing a cross-sectional structure of a coloring structure having a first structure, with respect to one embodiment of the coloring structure; 1A is a plan view showing a planar structure of an uneven structure in a first structure, and FIG. 1B is a cross-sectional view showing a cross-sectional structure of an uneven structure in the first structure, regarding an embodiment of a coloring structure. . FIG. 10 is a cross-sectional view showing a cross-sectional structure of a coloring structure having a second structure, with respect to one embodiment of the coloring structure; Regarding one embodiment of the coloring structure, (a) is a plan view showing the planar structure of the concave-convex structure composed only of the second convex elements in the second structure, and (b) is the second convex in the second structure. It is a cross-sectional view showing a cross-sectional structure of a concave-convex structure consisting of only partial elements. FIG. 10A is a plan view showing the planar structure of the concave-convex structure in the second structure, and FIG. 8B is a cross-sectional view showing the cross-sectional structure of the concave-convex structure in the second structure, regarding one embodiment of the coloring structure. . FIG. 10 is a cross-sectional view showing a cross-sectional structure of a modification of the color-developing structure according to the embodiment of the color-developing structure. FIG. 2 is a plan view showing a planar structure of a display for one embodiment of the display; FIG. 2 is a cross-sectional view showing a cross-sectional structure of a display in one embodiment of the display; 1 is a cross-sectional view showing a cross-sectional structure of a color-developing sheet in one embodiment of the color-developing sheet; FIG. FIG. 2 is a cross-sectional view showing a cross-sectional structure of a molded body for one embodiment of the molded body.

Embodiments of a coloring structure, a display, and a method for manufacturing the coloring structure will be described with reference to FIGS. 1 to 10. FIG.

[Color development structure]
The color-developing structure of the present embodiment is composed of an uneven structure including an uneven layer having an uneven structure and a multilayer film layer provided on the uneven structure. As the concave-convex structure of the concave-convex structure, for example, both the first structure and the second structure are applicable.
First, each of these two structures will be described.
Although the wavelength ranges of incident light and reflected light with respect to the coloring structure are not particularly limited, in the following description, as an example, a coloring structure intended for light in the visible light region will be described. In the present embodiment, light in the wavelength range of 360 nm to 830 nm is defined as light in the visible light range.

<First structure>
FIG. 1 shows a coloring structure 20 comprising an uneven structure 10 having a first structure.
The uneven structure 10 includes a substrate 15 which is an example of an uneven layer having an uneven structure on its surface, and a multilayer film layer 16 laminated on the surface of the substrate 15 . That is, the multilayer film layer 16 is formed on the uneven structure so as to cover the uneven surface of the substrate 15 . The concave-convex structure of the base material 15 is composed of a plurality of convex portions 15a and concave portions 15b that are regions between the plurality of convex portions 15a. consists of a portion extending to The substrate 15 contains inorganic particles having a particle diameter of 23% or less of the line width in the first direction in an amount of 3% by mass or more and 25% by mass or less relative to the solid content constituting the uneven layer.

The multilayer film layer 16 has a structure in which high refractive index layers 16a and low refractive index layers 16b are alternately laminated. The refractive index of the high refractive index layer 16a is higher than that of the low refractive index layer 16b. For example, the surface of the substrate 15 is in contact with the high refractive index layer 16a, and the surface of the multilayer film layer 16 opposite to the substrate 15 is configured with the low refractive index layer 16b.
The structure of the multilayer film layer 16 , that is, the materials, film thicknesses, and stacking order of the layers constituting the multilayer film layer 16 are the same on the convex portions 15 a and the concave portions 15 b of the base material 15 . The surface of the multilayer film layer 16 opposite to the base material 15 has a surface shape that follows the uneven structure of the base material 15 , that is, has an arrangement corresponding to the arrangement of the unevenness formed on the base material 15 . It has unevenness. Thereby, the multilayer film layer 16 has a surface shape that follows the uneven structure.

In such a structure, when light is incident on the color development structure 20 from the side where the multilayer film layer 16 is located (upper side in FIG. 1), the high refractive index layer 16a and the low refractive index layer 16b in the multilayer film layer 16 each The light reflected at the interface causes interference and changes its traveling direction due to irregular unevenness on the surface of the multilayer film layer 16 . As a result, light in a specific wavelength range is emitted at a wide angle. The specific wavelength range in which the reflected light is strongly emitted is determined by the materials and film thicknesses of the high refractive index layer 16a and the low refractive index layer 16b, and the width, height and arrangement of the convex portions 15a. Here, the specific wavelength range means, for example, a wavelength range in which multilayer interference occurs and/or a range in which the reflectance is enhanced by the concave-convex structure.

The surface of the multilayer film layer 16 is preferably covered with a protective layer. In this case, the uneven structure of the multilayer film layer 16 is prevented from collapsing, specifically, deformation of the uneven structure and clogging of the uneven structure with dirt or foreign matter.
In addition, since the surface of the multilayer film layer 16 in contact with the substrate 15 also has the same unevenness as the surface of the multilayer film layer 16, even if light enters the color-developing structure 20 from the side where the substrate 15 is located, Similarly, reflected light in a specific wavelength range is emitted at a wide angle. That is, the coloring structure 20 may be viewed from either the multilayer film layer 16 or the substrate 15 side.

With reference to FIG. 2, the details of the concave-convex structure of the substrate 15, which is the concave-convex layer, will be described.
2(a) is a plan view of the substrate 15 viewed from the direction facing the surface thereof, and FIG. 2(b) is a cross section of the substrate 15 along line 2-2 in FIG. 2(a). It is a sectional view showing a structure. In FIG. 2(a), the convex portions 15a forming the concave-convex structure are indicated by dots. The representation of FIG. 2(a) corresponds to a pattern formed by a set of a plurality of graphic elements, which is a projected image of a convex portion on a virtual plane.
As shown in FIG. 2A, the first direction Dx and the second direction Dy are directions along a virtual plane, which is a virtual plane on which the uneven structure is projected in the thickness direction of the base material 15. , the first direction Dx and the second direction Dy are orthogonal. The virtual plane is a plane along the direction in which the substrate 15 spreads, and is represented by a plane orthogonal to the thickness direction of the substrate 15 .

On the virtual plane, the pattern formed by the projection image of the convex portion 15a is a pattern consisting of a set of a plurality of rectangles R indicated by dashed lines. A rectangle R is an example of a graphic element. The rectangle R has a shape extending in the second direction Dy, and in the rectangle R, the length d2 in the second direction Dy is greater than or equal to the length d1 in the first direction Dx. The multiple rectangles R are arranged so as not to overlap in either the first direction Dx or the second direction Dy.
The plurality of rectangles R have a constant length d1 in the first direction Dx, and the plurality of rectangles R are arranged in the first direction Dx at intervals of length d1, that is, at intervals of length d1. . The line width in the first direction means this d1.

On the other hand, in the plurality of rectangles R, the length d2 in the second direction Dy is irregular, that is, has a plurality of lengths, and the length d2 in each rectangle R is selected from a population with a predetermined standard deviation value. This population preferably follows a normal distribution. A pattern consisting of a plurality of rectangles R is obtained by, for example, temporarily arranging a plurality of rectangles R having a length d2 distributed with a predetermined standard deviation in a predetermined area, and determining whether or not each rectangle R is actually arranged according to a certain probability. By determining, it is formed by setting an area where the rectangle R is arranged and an area where the rectangle R is not arranged. In order to efficiently scatter the reflected light from the multilayer film layer 16, the length d2 preferably has a distribution with an average value of 4.15 μm or less and a standard deviation of 1 μm or less.

When the area where the rectangles R are arranged is the area where the convex portion 15a is arranged and the adjacent rectangles R are in contact with each other, 1 Two convex portions 15a are arranged. In such a configuration, the length of the convex portion 15a in the first direction Dx is an integral multiple of the length d1 of the rectangle R.

The length d1 in the first direction Dx in the rectangle R is set to be equal to or less than the wavelength of light in the visible light region in order to suppress the occurrence of rainbow-colored spectrum due to unevenness. In other words, the length d1 has a length below the sub-wavelength, ie below the wavelength band of the incident light. That is, the length d1 is preferably 830 nm or less, more preferably 700 nm or less. Furthermore, the length d1 is preferably smaller than the peak wavelength of the light in the specific wavelength range reflected from the multilayer film layer 16. FIG. For example, the length d1 is preferably about 300 nm when the color-developing structure 20 is used to develop a blue color, and the length d1 is preferably about 400 nm when the color-developing structure 20 is used to develop a green color. Preferably, when the coloring structure 20 is to develop a red color, the length d1 is preferably about 460 nm.

In order to increase the spread of the reflected light from the multilayer film layer 16, that is, to enhance the scattering effect of the reflected light, it is preferable that the uneven structure has many undulations. , the ratio of the area occupied by the convex portion 15a per unit area is preferably 40% or more and 60% or less. For example, when viewed from the direction facing the surface of the base material 15, the ratio of the areas of the convex portions 15a and the concave portions 15b per unit area is preferably 1:1.

As shown in FIG. 2(b), the height h1 of the convex portion 15a is constant, and the desired color to be developed by the coloring structure 20, that is, the wavelength range desired to be reflected from the coloring structure 20 is obtained. It may be set accordingly. If the height h1 of the convex portion 15a is larger than the surface roughness of the multilayer film layer 16 on the convex portion 15a and the concave portion 15b, the scattering effect of the reflected light can be obtained.
However, in order to suppress interference of light caused by reflection on the unevenness of the surface of the multilayer film layer 16, the height h1 of the convex portion 15a is preferably 1/2 or less of the wavelength of light in the visible light region. That is, it is preferably 415 nm or less. Furthermore, in order to suppress the interference of the light, the height h1 is more preferably 1/2 or less of the peak wavelength of the light in the specific wavelength range reflected from the multilayer film layer 16 .

In addition, if the height h1 of the convex portion 15a is excessively large, the scattering effect of the reflected light becomes too high, and the intensity of the reflected light tends to decrease. The height h1 of 15a is preferably 10 nm or more and 200 nm or less. For example, in the color-developing structure 20 exhibiting blue color, the height h1 of the protrusions 15a is preferably about 40 nm or more and 150 nm or less in order to obtain an effective spread of light. In order to suppress the height h1 of the convex portion 15a, it is preferable that the height h1 is 100 nm or less.

Note that the rectangles R may form a pattern of the protrusions 15a on the virtual plane by arranging two rectangles R aligned along the first direction Dx such that parts of the rectangles R 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 interval of the rectangles R may not be constant. In the portion where the rectangles R overlap, one convex portion 15a is located in one area where the areas where the rectangles R are arranged are combined. In this case, the length of the convex portion 15a in the first direction Dx is different from the integral multiple of the length d1 of the rectangle R. In addition, the length d1 of the rectangle R may not be constant. should be greater than the standard deviation. Even with such a configuration, the effect of scattering the reflected light can be obtained.

<Second structure>
FIG. 3 shows a coloring structure 21 comprising a concave-convex structure 11 having a second structure.
Compared with the uneven structure 10 having the first structure, the uneven structure 11 having the second structure has the uneven structure on the substrate 15, that is, the uneven structure on the surface of the multilayer film layer 16. different. It has the same configuration as the concave-convex structure body 10 having the above-described first structure except for the configuration of such a concave-convex structure. In the following, the coloring structure 21 will be described with a focus on the differences from the above-described coloring structure 20, and the same components as those of the coloring structure 20 will be assigned the same reference numerals and description thereof will be omitted.

Convex portions 15c that form the concavo-convex structure of the substrate 15 in the concavo-convex structure 11 are composed of first convex elements having the same configuration as the convex portions 15a in the first structure and second convex elements that extend in a strip shape. , are stacked in the thickness direction of the substrate 15 .
According to the coloring structure 20 of the first structure, the reflected light scattering effect slows down the change in the visually recognized color depending on the observation angle, but the reflected light intensity decreases due to the scattering. Color vibrancy is reduced. Depending on the application of the coloring structure, there are cases where a structure that allows observation of brighter colors at a wider viewing angle is required. In the second structure, the second convex elements are arranged so that incident light is strongly diffracted in a specific direction, and the light scattering effect of the first convex elements and the light scattering effect of the second convex elements are combined. The diffraction effect realizes the coloring structure 21 that allows observation of brighter colors at a wider viewing angle.

The configuration of the second projection element will be described with reference to FIG. FIG. 4(a) is a plan view of a concavo-convex structure consisting only of second convex elements, and FIG. 4(b) is a cross-sectional view showing the cross-sectional structure taken along line 4-4 in FIG. 4(a). be. In FIG. 4(a), the second convex elements are indicated by dots. The display in FIG. 4A corresponds to a pattern formed by a set of a plurality of graphic elements, which are projected images of convex portions on a virtual plane.

As shown in FIG. 4(a), in plan view, that is, in the virtual plane, the second convex element 15Eb has a band shape extending with a constant width along the second direction Dy, and has a plurality of second convex elements 15Eb. The convex elements 15Eb are arranged at intervals along the first direction Dx. In other words, the pattern formed by the projected image of the second convex element 15Eb on the virtual plane is a pattern consisting of a plurality of belt-like regions extending along the second direction Dy and arranged along the first direction Dx. The length d3 of the second convex element 15Eb in the first direction Dx 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 elements 15Eb in the first direction Dx, that is, the arrangement interval of the band-like regions in the first direction Dx is at least part of the light reflected on the surface of the concave-convex structure formed by the second convex elements 15Eb. part is set so as to be observed as first-order diffracted light. The first-order diffracted light is, in other words, diffracted light whose diffraction order m is 1 or 1. That is, when the incident angle of incident light is θ, the reflection angle of reflected light is φ, and the wavelength of diffracted light is λ, the arrangement interval de satisfies de≧λ/(sin θ+sin φ). For example, when targeting visible light with λ=360 nm, the arrangement interval de of the second convex elements 15Eb may be 180 nm or more. 1/2 or more. The arrangement interval de is the distance along the first direction Dx between the ends of two adjacent second convex elements 15Eb, and is the same for the second convex elements 15Eb in the first direction Dx. is the distance between the ends located on the sides of the

The periodicity of the pattern formed by the second convex elements 15Eb is reflected in the periodicity of the concave-convex structure of the substrate 15, that is, the periodicity of the concave-convex structure on the surface of the multilayer film layer 16. FIG. When the arrangement interval de of the plurality of second convex elements 15Eb is constant, the diffraction phenomenon on the surface of the multilayer film layer 16 causes reflected light of a specific wavelength to be emitted from the multilayer film layer 16 at a specific angle. . The reflection intensity of the light due to this diffraction is much stronger than the reflection intensity of the reflected light caused by the light scattering effect of the first convex element described in the above-described first structure. Light with brilliance is visible, but on the other hand, a spectrum occurs due to diffraction, and the visible color changes according to the change in viewing angle.

Therefore, for example, even if the structure of the first convex elements is designed so as to obtain the coloring structure 21 exhibiting blue color, the arrangement interval de of the second convex elements 15Eb is set to a constant value in the range of, for example, 400 nm or more and 5 μm or less. When set to , depending on the viewing angle, strong green to red light due to surface reflection due to diffraction is observed. On the other hand, for example, if the arrangement interval de of the second convex elements 15Eb is increased to about 50 μm, the range of angles at which the light in the visible light region is diffracted becomes narrower, so that the color change due to diffraction becomes visible. Although it becomes difficult, light with metallic luster is only observed at a specific viewing angle.

Therefore, if the pattern of the second convex elements 15Eb is a pattern in which a plurality of periodic structures with different periods are superimposed instead of setting the array interval de to a constant value, light of a plurality of wavelengths will be mixed in the reflected light due to diffraction. Therefore, highly monochromatic light that has been spectrally separated becomes less visible. Therefore, bright and glossy colors can be observed at a wide viewing angle. In this case, the arrangement interval de is selected, for example, from the range of 360 nm or more and 5 μm or less, and the average value of the arrangement interval de of the plurality of second convex elements 15Eb is 1/1/ of the minimum wavelength in the wavelength range included in the incident light. 2 or more is sufficient.

However, as the standard deviation of the arrangement interval de increases, the arrangement of the second convex elements 15Eb 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 elements 15Eb is determined according to the angle at which the light spreads due to the light scattering effect of the first convex elements. It is preferable to determine For example, when the reflected blue light is emitted in a range of ±40° with respect to the incident angle, in the pattern of the second convex elements 15Eb, the arrangement interval de is set to 1 μm or more and 5 μm or less. It is set so that the standard deviation is about 1 μm. As a result, reflected light due to diffraction occurs at an angle that is approximately the same as the angle at which the light spreads due to the light scattering effect of the first convex element.

That is, unlike a structure for diffracting and extracting light in a specific wavelength range, the structure composed of a plurality of second convex elements 15Eb utilizes diffraction to diffract light into a predetermined angular range due to the dispersion of the array spacing de. It is a structure for emitting light of various wavelength ranges.

Furthermore, in order to generate a longer-period diffraction phenomenon, a square area with a side of 10 μm or more and 100 μm or less is used as a unit area, and in the pattern of the second convex elements 15Eb for each unit area, the arrangement interval de is It may be about 1 μm or more and 5 μm or less, and the standard deviation may be about 1 μm. Note that the plurality of unit regions may include a region having a constant array interval de within a range of 1 μm to 5 μm. Even if there is a unit area with a constant array interval de, if the array interval de varies with a standard deviation of about 1 μm in any of the unit areas adjacent to this unit area, the resolution of the human eye is reduced. can be expected to have the same effect as the configuration in which the arrangement interval de varies in all the unit regions.

The second convex elements 15Eb shown in FIG. 4 have periodicity only in the first direction Dx due to the arrangement interval de. The light scattering effect of the first convex elements mainly acts on the reflected light in the direction along the first direction Dx when viewed from the direction facing the surface of the base material 15, but the light reflected in the second direction Dy It may also partially affect the reflected light in the direction along the . Therefore, the second convex elements 15Eb may also have periodicity in the second direction Dy. That is, the pattern of the second convex element 15Eb may be a pattern in which a plurality of band-like 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 elements 15Eb, for example, each of the arrangement intervals along the first direction Dx and the arrangement interval along the second direction Dy of the band-like regions has an average value of 1 μm or more and 100 μm or less. It suffices if there is some variation. In addition, the average value of the arrangement intervals along the first direction Dx and The average value of the array spacing along the two directions Dy may be different from each other, and the standard deviation of the array spacing along the first direction Dx and the standard deviation of the array spacing along the second direction Dy are different from each other. may be

As shown in FIG. 4B, the height h2 of the second protrusion element 15Eb should be larger than the surface roughness of the multilayer film layer 16 on the protrusions 15c and recesses 15b. However, as the height h2 of the second convex element 15Eb increases, the diffraction effect of the second convex element 15Eb becomes dominant in the effect of the concave-convex structure on the reflected light, and the scattering of light by the first convex element Since it becomes difficult to obtain the effect, it is preferable that the height h2 of the second convex element 15Eb is approximately the same as the height h1 of the first convex element, and the height h2 of the second convex element 15Eb is equal to the height It may match h1. For example, the height h1 of the first convex element and the height h2 of the second convex element 15Eb are preferably within the range of 10 nm or more and 200 nm or less. The height h1 of the first convex element and the height h2 of the second convex element 15Eb are preferably within the range of 10 nm or more and 150 nm or less.

<Composite Structure of First Structure and Second Structure>
Details of the uneven structure of the uneven structure 11 having the first structure and the second structure will be described with reference to FIG. 5 . 5(a) is a plan view of the substrate 15 viewed from the direction facing the surface thereof, and FIG. 5(b) is a cross section of the substrate 15 taken along line 5-5 in FIG. 5(a). It is a sectional view showing a structure. In FIG. 5(a), the pattern formed by the first convex element and the pattern formed by the second convex element are shown with dots having different densities. The representation of FIG. 5(a) corresponds to a pattern formed by a set of a plurality of graphic elements, which is a projected image of a convex portion on a virtual plane.

As shown in FIG. 5(a), on the virtual plane, the pattern formed by the projected image of the convex portion 15c is a first pattern formed by the projected image of the first convex portion element 15Ea, and the second pattern formed by the projected image of the first convex portion element 15Ea. It is composed of a pattern in which a second pattern, which is a pattern composed of projected images of the projection elements 15Eb, is superimposed. That is, in the region where the convex portion 15c is located, there are a region S1 composed only of the first convex element 15Ea, a region S2 in which the first convex element 15Ea and the second convex element 15Eb overlap, and a second convex element 15Eb. A region S3 composed only of two convex elements 15Eb is included. In FIG. 5, the first convex element 15Ea and the second convex element 15Eb are superimposed so that their ends are aligned in the first direction Dx. The end of the projection element 15Ea and the end of the second projection element 15Eb may be displaced.

As shown in FIG. 5(b), in the region S1, the height of the projection 15c is the height h1 of the first projection element 15Ea. In the region S2, the height of the convex portion 15c is the sum of the height h1 of the first convex element 15Ea and the height h2 of the second convex element 15Eb. In addition, in the region S3, the height of the projection 15c is the height h2 of the second projection element 15Eb. In this way, the projected image of the projection 15c on the virtual plane constitutes the first pattern, and the projected image on the virtual plane constitutes the second pattern of the first projection element 15Ea having a predetermined height h1. , and a second convex element 15Eb having a predetermined height h2 are stacked in the height direction to form a multi-stage shape. The convex portion 15c can also be regarded as a structure in which the second convex element 15Eb is superimposed on the first convex element 15Ea, or a structure in which the first convex element 15Ea is superimposed on the second convex element 15Eb. It is also possible to capture

In such a structure, since the uneven structure on the surface of the multilayer film layer 16 is more complicated than the first structure, the uneven structure may be deformed depending on the usage. In that case, the uneven structure of the multilayer film layer 16 may be protected by providing a protective layer.

As described above, according to the coloring structure 21 having the second structure, the light diffusion phenomenon caused by the portion of the protrusion 15c formed by the first protrusion element 15Ea and the second protrusion element 15Eb are formed. Reflected light in a specific wavelength range can be observed at a wide viewing angle by synergy with the diffraction phenomenon of light caused by the part where it is located, and by increasing the intensity of this reflected light, bright colors with a glossy feeling visible. In other words, in the second structure, the convex portion 15c, which is one structural body, has two functions of diffusing light and diffracting light.

In the virtual plane, the pattern formed by the first convex element 15Ea and the pattern formed by the second convex element 15Eb are arranged so that the first convex element 15Ea and the second convex element 15Eb do not overlap each other. may be placed in Even with this structure, the light diffusion effect by the first convex element 15Ea and the light diffraction effect by the second convex element 15Eb can be obtained. However, if the first convex element 15Ea and the second convex element 15Eb are arranged so as not to overlap each other, the first convex element 15Ea can be arranged per unit area compared to the first structure. area becomes smaller, and the light diffusion effect decreases. Therefore, in order to enhance the light diffusion effect and diffraction effect of the convex elements 15Ea and 15Eb, as shown in FIG. It is preferable to make 15c into a multistage shape.

[Manufacturing method of coloring structure]
The material of each layer constituting the coloring structures 20 and 21 and the manufacturing method of the coloring structures 20 and 21 will be described.
The base material 15 is made of, for example, a synthetic quartz substrate or a film made of a resin such as polyethylene terephthalate (PET) or polyurethane. The uneven structure on the surface of the substrate 15 can be formed by directly processing the surface of the substrate using microfabrication techniques such as lithography and dry etching that irradiate light or charged particle beams. is time consuming and very costly. Therefore, it is desirable to fabricate the concave-convex structure by transferring the concave-convex structure from the mold having the concave-convex structure formed by these techniques by the nanoimprint method. The curing method in the nanoimprint method may be either light or heat.

As the base material 15 produced by the nanoimprint method, conventionally known resins can be used as long as they are resins that allow the film to stand on its own after curing and/or drying. Examples of resins include polyurethane, epoxy, silicone, acrylic, polyethylene terephthalate, polyethylene, and polypropylene, but are not limited to these. The resin means a resin after curing and/or drying, and may be in a non-polymerized state such as a monomer, oligomer, or prepolymer before curing and/or drying. For example, a mixture of polyol and isocyanate can be thermally cured, and photocuring can be performed by adding a photoradical polymerization initiator to an acrylic monomer.

The resin can be spread by using a bar coater or an applicator, or by applying pressure. In addition, the base material 15 can be produced by a conventionally known method.
Also, if the viscosity of the resin is high, it takes time to fill the mold. High pressure or high temperature filling is possible, but costly. Therefore, it is desirable that the viscosity is low at the time of mold filling.
Forming by extrusion lamination is also possible, but it is difficult to fill due to its high viscosity, and it is very difficult to select appropriate process conditions.

The uneven structure of the second structure is formed, for example, by sequentially performing etching using the resist pattern of the first pattern and etching using the resist pattern of the second pattern. At this time, either the etching of the first pattern or the etching of the second pattern may be performed first. That is, either the first convex element 15Ea or the second convex element 15Eb may be formed first. The concave-convex structure formed by these techniques may be transferred to a resin by the nanoimprint method described above.

The high refractive index layer 16a and the low refractive index layer 16b that constitute the multilayer film layer 16 are made of a material that is transparent to light in the visible region, that is, a material that is transparent to light in the visible region. Configured. Materials for these layers are not limited as long as the refractive index of the high refractive index layer 16a is higher than that of the low refractive index layer 16b. The greater the difference in index, the more intense reflected light can be obtained with a smaller number of layers. From this point of view, for example, when the high refractive index layer 16a and the low refractive index layer 16b are made of an inorganic material, the high refractive index layer 16a is made of titanium dioxide (TiO ₂ ), and the low refractive index layer 16b is made of silicon dioxide. It is preferably composed of (SiO ₂ ). Each of the high refractive index layer 16a and the low refractive index layer 16b made of such an inorganic material is formed using known thin film forming techniques such as sputtering, vacuum deposition, or atomic layer deposition. Moreover, each of the high refractive index layer 16a and the low refractive index layer 16b may be composed of an organic material. technique should be used.

The film thickness of each of the high refractive index layer 16a and the low refractive index layer 16b may be designed using a transfer matrix method or the like according to the desired color to be developed by the coloring structures 20 and 21. FIG. For example, when forming the coloring structures 20 and 21 exhibiting blue, the thickness of the high refractive index layer 16a made of TiO ₂ is preferably about 40 nm, and the thickness of the low refractive index layer 16b made of SiO ₂ is preferably about 40 nm. is preferably about 75 nm.

1 and 3, as the multilayer film layer 16, the multilayer film layer 16 consists of 10 layers in which a high refractive index layer 16a and a low refractive index layer 16b are alternately laminated in this order from a position close to the base material 15. exemplified. However, the number of layers and the order of lamination of the multilayer film layer 16 are not limited to this. good. For example, the low refractive index layer 16b may be in contact with the surface of the substrate 15, and the high refractive index layer 16a and the low refractive index layer 16b may be alternately laminated thereon. Also, the layer constituting the outermost surface, which is the surface opposite to the substrate 15 in the multilayer film layer 16, may be either the high refractive index layer 16a or the low refractive index layer 16b. Furthermore, if the low refractive index layers 16b and the high refractive index layers 16a are alternately laminated, the layer in contact with the surface of the substrate 15 and the layer forming the outermost surface are made of the same material. good too. Furthermore, the multilayer film layer 16 may be composed of a combination of three or more layers with different refractive indices.

In short, the multilayer film layer 16 has mutually adjacent layers with different refractive indices, and the reflectance of light in a specific wavelength range among the incident light incident on the multilayer film layer 16 is lower than the reflectance in other wavelength ranges. It is sufficient if it is configured to be higher than the rate.
When the color-developing structures 20 and 21 are viewed from the side where the multilayer film is located, a material having optical transparency to light in the visible light region, i.e., a material having optical transparency to light in the visible light region A transparent material may be used to form the protective layer. Examples of such materials include acrylics, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polyethylene, and resins such as polyvinyl chloride, polycarbonate, polyvinyl alcohol, polystyrene, and polyamide. This protective layer may contain an ultraviolet absorber.

Here, when the concave-convex structures 10 and 11 are formed of a material transparent to light in the visible light region, a specific light reflected by the multilayer film layer 16 is included in the wavelength range included in the incident light. A part of the light in the wavelength range other than the wavelength range of 1 is transmitted through the multilayer film layer 16 and further the concave-convex structures 10 and 11 . Therefore, when observing the concave-convex structures 10 and 11 from one of the front and back sides, if there is a light source or a structure that reflects transmitted light such as a white plate on the other side of the concave-convex structures 10 and 11, the one side may Then, along with the reflected light in a specific wavelength range from the multilayer film layer 16, the transmitted light that has passed through the multilayer film layer 16 from the other side is visually recognized. As described above, the wavelength range of this transmitted light is different from the wavelength range of the reflected light, and the color of the transmitted light is primarily the complementary color of the color of the reflected light. Therefore, when such transmitted light is visually recognized, the visibility of colors due to reflected light is reduced.

Therefore, it is desirable that the coloring structures 20 and 21 contain a material that absorbs the transmitted light that has passed through the multilayer film.
For example, an absorption layer that absorbs transmitted light may be provided on the multilayer film layer 16 . According to such a configuration, the light transmitted through the multilayer film layer 16 from the substrate 15 side is absorbed by the absorption layer on the multilayer film layer 16, and the transmitted light is suppressed from returning to the substrate 15 side. When the coloring structures 20 and 21 are observed from the material 15 side, light in a wavelength range different from the reflected light from the multilayer film layer 16 is suppressed from being visually recognized. Therefore, deterioration of color visibility due to reflected light is suppressed, and desired color development is preferably obtained in the color development structures 20 and 21 .
Alternatively, an absorption layer may be provided on the surface of the substrate opposite to the uneven structure. According to such a configuration, the light transmitted through the substrate 15 from the multilayer film layer 16 is absorbed by the absorption layer that absorbs the transmitted light provided on the side opposite to the concave-convex structure. Visibility of light in different wavelength ranges is suppressed.

Further, when a material that absorbs transmitted light is included in the uneven layer, the light transmitted through the multilayer film layer 16 is absorbed by the base material 15, so light in a wavelength range different from the reflected light is visible. be suppressed. With such a configuration, there is no need to provide an absorption layer separately, and the manufacturing process can be simplified. However, since the mold may be contaminated depending on the size and amount of particles added when producing the concave-convex structure, inorganic particles having a particle size of 23% or less of the line width in the first direction are added to the solid content constituting the concave-convex layer. On the other hand, it is necessary to contain 3% by mass or more and 25% by mass or less.
The material that absorbs transmitted light means a material that absorbs light in the visible light range, such as light absorbers and black pigments. Specific examples include carbon black, titanium black, black iron oxide, and black composite oxide. It is preferably a layer in which a black inorganic pigment such as a substance is mixed with a resin.

[Modified example of coloring structure]
The coloring structure may have the configuration shown in FIG. The concave-convex structure 12 included in the coloring structure 22 shown in FIG. The surface of the base material 15 is flat, and the resin layer 17 has irregularities on its surface. In the form shown in FIG. 6, the resin layer 17 constitutes the uneven layer. As the concave-convex structure on the surface of the resin layer 17, for example, either the concave-convex structure of the first structure or the concave-convex structure of the second structure, or a composite structure thereof can be applied.

As a method for forming the uneven structure of the resin layer 17, for example, a nanoimprint method is used. For example, when forming the concave-convex structure of the resin layer 17 by the photo-nanoimprint method, first, a resin forming the resin layer 17 is applied to the concave-convex surface of a mold, which is an intaglio plate having concave-convex patterns reversed from the concave-convex structure to be formed. As a result, a photocurable resin is applied. The method of applying the photocurable resin is not particularly limited, and known 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 substrate 15 is superimposed on the surface of the coating layer made of the photocurable resin, and light is irradiated from the substrate 15 side or the mold side while the coating layer and the mold are pressed against each other. Subsequently, the mold is released from the cured photocurable resin and the substrate 15 . As a result, the unevenness of the mold is transferred to the photocurable resin, and the resin layer 17 having unevenness on the surface is formed. The mold is made of, for example, synthetic quartz or silicon, and is formed using known microfabrication techniques such as lithography or dry etching that irradiates light or charged particle beams.

The photocurable resin may be applied to the surface of the base material 15 and the light may be irradiated while the mold is pressed against the coating layer on the base material 15 .
Also, a thermal nanoimprinting method may be used instead of the photonanoimprinting method. In this case, as the resin for the resin layer 17, a resin such as a thermoplastic resin or a thermosetting resin is used according to the manufacturing method. Even when a photocurable resin is used, a thermal nanoimprint method can be used by using a thermal radical initiator or the like.

The thermal nanoimprint method has the disadvantage of requiring more time for curing than the photonanoimprint method, but has the advantage of being able to form uneven layers with low visible light transmittance, which is difficult with photonanoimprinting because of thermal curing. In order to achieve thermal curing in a short time, a curing agent with a low curing temperature or a short curing time should be selected. One of the harmful effects of using such hardeners is shortening of the pot life of the coating liquid, but the problem of pot life can be solved by adding the hardening agent to the coating liquid by injection immediately before coating. can.

Pressure may be applied to the resin and mold during curing. However, if the viscosity of the resin is low, it is not necessary to apply pressure because the resin enters the concave-convex structure due to capillary action. When no pressure is applied, there is a concern that defects may occur in the concave-convex structure due to inclusion of air bubbles, so it is preferable to remove air bubbles by optimizing the filtering and curing and/or drying conditions of the coating liquid.

[Characteristics of uneven layer]
When these color-developing structures are deteriorated by being exposed to the outdoors for a long time, the base material 15, the resin layer 17, and the like may turn yellow, and the hue of the structural color may change. Therefore, the uneven layer needs to contain inorganic particles having a particle diameter of 23% or less of the line width in the first direction in an amount of 3% by mass or more and 25% by mass or less based on the solid content constituting the uneven layer. The uneven layer here means a layer forming an uneven structure. For example, when the substrate 15 has an uneven structure as shown in FIG. When the layer 17 has an uneven structure, the resin layer 17 is called an uneven layer.

By containing the inorganic particles, the light transmittance of the uneven layer can be suppressed by the scattering effect of the particles and the absorption effect of transmitted light. If the inorganic particles are less than 3% by mass, the scattering effect of the inorganic particles and the absorption effect of transmitted light are reduced, and hue change cannot be prevented. On the other hand, if it is more than 25% by mass, the mold for transferring the concave-convex structure is contaminated due to falling off of the inorganic particles. Contamination may also occur due to the inorganic particles dropping off from parts other than the mold. Moreover, when the amount added increases, the ratio of the resin decreases, the coating film becomes brittle, and cracks may occur in the coating film when molding the coloring structure.

If the particle size of the inorganic particles is larger than 23% of the line width in the first direction, the falling off of the inorganic particles contaminates the mold for transferring the concave-convex structure. The particle size referred to here indicates the average particle size of primary particles per particle measured with a scanning electron microscope. If the average particle size per particle is within this range, aggregates may be included.
By containing inorganic particles having a particle diameter of 23% or less with respect to the line width in the first direction in an amount of 3% by mass or more and 25% by mass or less with respect to the solid content of the uneven layer, the hue after long-term storage of the coloring structure A change can be prevented, and contamination of the mold can be prevented when transferring the concave-convex structure from the mold.

Furthermore, by containing inorganic particles, it is possible to impart pasting properties to the uneven layer. By imparting pasting properties, the coloring structure can be easily attached to an adherend without using an adhesive layer or an adhesive, although the adhesive strength is inferior to that in the case of using an adhesive layer. Within the above range, there is no concern that the coloring structure will be peeled off, and there will be no concern that a large amount of particles will adhere to the glue side and the performance of the glue will be reduced.
Examples of inorganic particles include silica, carbon black, and titanium black. The number of inorganic particles does not have to be one, and plural kinds may be included.

When carbon black is used, the visible light transmittance of the uneven layer is reduced, and since carbon black has strong weather resistance, it is possible to strongly prevent hue change after long-term storage. In addition, when the coloring structure is observed from the multilayer film side, deterioration in visibility due to light transmitted from the substrate side of the coloring structure can be suppressed. In this case, good visibility can be obtained from the multilayer film layer 16 side.
When titanium black is used, the visible light transmittance of the concavo-convex layer is reduced, so that hue change after long-term storage can be prevented. In addition, there is no need to separately provide an absorbent layer necessary to improve visibility. In addition, since titanium black has the property of transmitting ultraviolet light, it can be manufactured by optical nanoimprinting. In this case, good visibility can be obtained from the multilayer film layer 16 side.

It should be noted that the concave-convex layer may have a light-absorbing structure that absorbs at least part of the light that passes through the multilayer film layer 16, even if it does not absorb all of the light in the visible light region. With such a structure, it is possible to obtain an effect of suppressing deterioration in color visibility due to reflected light, as compared with a structure in which such a light-absorbing layer is not provided. Therefore, the uneven layer may be a layer containing a pigment having a color corresponding to the wavelength range of light that passes through the multilayer film layer 16 as long as it is within the range specified above. However, if the uneven layer is a black layer containing a black pigment, it is not necessary to adjust the color of the uneven layer according to the wavelength range of the transmitted light, and the uneven layer absorbs light in a wide wavelength range. , the deterioration of color visibility due to reflected light can be suppressed easily and preferably. However, the pigment must be within the above-specified range because the mold will be contaminated.

In particular, when the visible light transmittance of the uneven layer with respect to incident light is 15% or less, deterioration in color visibility due to reflected light is preferably suppressed. In this case, good visibility can be obtained from the multilayer film layer 16 side. There is no particular lower limit of visible light transmittance for incident light, and 0% is not a problem.
The uneven layer may contain conventionally known materials such as additives within a range that does not impair the performance.

[Example of application of coloring structure]
A specific application example of the coloring structure described above will be described. Any of the coloring structure 20 having the first structure, the coloring structure 21 having the second structure, and the coloring structure 22 described in the modification above can be applied to the application examples described below. is.

<Display body>
A first application example of the coloring structure is a form in which the coloring structure is used for a display. The indicator may be used for the purpose of increasing the difficulty of counterfeiting the article, may be used for the purpose of improving the design of the article, or may be used for both purposes. For the purpose of increasing the difficulty of counterfeiting goods, for example, the display can be used on authentication documents such as passports and driver's licenses, securities such as gift certificates and checks, cards such as credit cards and cash cards, banknotes, etc. can be pasted. In addition, for the purpose of improving the design of the article, the display body may be, for example, an ornament worn on the body, an article carried by the user, an article to be placed such as furniture or home appliances, or a wall or door. It can be attached to structures, interiors and exteriors of automobiles, and the like.

As shown in FIG. 7, the display 30 has a front surface 30F and a back surface 30R opposite to the front surface 30F. The display 30 includes a first display area 31A and a second display area 31B when viewed from the direction facing the surface 30F. The first display region 31A is a region in which a plurality of first pixels 32A are arranged, and the second display region 31B is a region in which a plurality of second pixels 32B are arranged. In other words, the first display region 31A is composed of a set of first pixels 32A, and the second display region 31B is composed of a set of second pixels 32B. The structure of the coloring structure is applied to each of the first pixels 32A and the second pixels 32B, and the first pixels 32A and the second pixels 32B present colors of different hues. That is, when viewed from the direction facing the surface 30F of the display body 30, different hues are visually recognized in the first display area 31A and the second display area 31B.

Each of the first display area 31A and the second display area 31B is a character, a symbol, a figure, a pattern formed by a projection image of the convex portion by these areas alone or by a combination of two or more of these areas. It expresses patterns, patterns, and their backgrounds. As an example, in the configuration shown in FIG. 7, a circular figure is represented by the first display area 31A, and a triangular figure is represented by the second display area 31B.
Note that the display body 30 has a region having a structure different from that of the coloring structure around the display regions 31A and 31B, for example, a region having a structure in which a multilayer film layer is laminated on a substrate having a flat surface. Alternatively, it may have a region having a structure in which a metal thin film is laminated on the base material.
A display area may also be arranged on the rear surface 30R.

FIG. 8 is a diagram showing a cross-sectional structure of the first pixel 32A and the second pixel 32B. FIG. 8 shows an example in which the coloring structures 23 forming these pixels 32A and 32B are coloring structures having the first structure.
The height h1 of the convex portion 15a differs between the first pixel 32A and the second pixel 32B. On the other hand, the structure of the multilayer film layer 16 is common between the first pixel 32A and the second pixel 32B. That is, the material and film thickness of the high refractive index layer 16a, the material and film thickness of the low refractive index layer 16b, and the number of layers of these layers are common. Since the height h1 of the convex portion 15a differs between the first pixel 32A and the second pixel 32B, the first pixel 32A and the second pixel 32B exhibit different hues. The height h1 of the convex portion 15a in each pixel 32A, 32B may be set according to the desired hue of each pixel 32A, 32B.

Here, the larger the difference between the height h1a of the convex portion 15a of the first pixel 32A and the height h1b of the convex portion 15a of the second pixel 32B, the greater the difference between the hue exhibited by the first pixel 32A and the hue exhibited by the second pixel 32B. The difference from the hue becomes large, and the hue difference is easily recognized by the human eye. For example, the difference between the height h1a and the height h1b is preferably 5 nm or more, and is 1% or more of the peak wavelength of the reflected light from the multilayer film layer 16 when the multilayer film layer 16 is laminated on a flat surface. is preferably
For example, when the peak wavelength of the reflected light from the multilayer film layer 16 is 500 nm when the multilayer film layer 16 is laminated on a flat surface, and the pixel is to emit green, the height h1 of the convex portion 15a is set to The height h1 of the protrusions 15a is preferably about 200 nm when it is desired to make the pixel emit red color.

In the above configuration, the height of the uneven structure on the surface of the multilayer film layer 16 is different between the first display region 31A and the second display region 31B, and the height of the display body 30 is higher than when the height is constant. Since the overall uneven structure is complicated, the uneven structure of the multilayer film layer 16 may be protected by a protective layer.
When the coloring structure applied to the pixels 32A and 32B is the coloring structure having the second structure, the first projection element 15Ea is formed in the pattern formed by the projected image of the projection 15c on the virtual plane. In a configuration in which the proportion of the second convex element 15Eb is smaller than the proportion of , the influence of the height h2 of the second convex element 15Eb on the hue exhibited by the pixels 32A and 32B is minimal. Therefore, even in the coloring structure having the second structure, it is possible to adjust the hue exhibited by the pixels 32A and 32B by adjusting the height h1 of the first convex element 15Ea corresponding to the convex portion 15a of the first structure. is.

The pattern of the convex portion 15a is set, for example, for each first pixel 32A and each second pixel 32B. That is, the average value and standard deviation of the lengths d1 and d2 of the plurality of rectangles R forming the projected image pattern of the convex portion 15a are set for each of the pixels 32A and 32B. The pattern of the convex portion 15a may be different for each of the pixels 32A and 32B, or may be the same. The size of the pixels 32A, 32B may be set according to the desired resolution of the image formed by the display areas 31A, 31B. In order to display an image with higher precision, it is preferable that each side of the pixels 32A and 32B is 10 μm or more.

Note that, when manufacturing the pixels 32A and 32B, for example, after collectively forming a convex portion according to a pattern consisting of a plurality of rectangles R in a large-area region, the convex portion is cut so as to divide the pattern. The concave-convex structure of each pixel 32A, 32B may be formed by dividing by a method or the like, and such a manufacturing method is preferable because the manufacturing process is facilitated. Here, due to the division of the convex portion, in some of the plurality of pixels 32A and 32B, the length d2 in the second direction Dy is longer than the length d1 in the first direction Dx at the ends of the pixels 32A and 32B. A convex portion forming a small rectangle R may be formed. However, even if such rectangles R are included in the pattern of the projections 15a, if the proportion of the rectangles R is sufficiently small, the optical influence of the rectangles R is negligibly small.

The substrate 15 is continuous between the first pixel 32A and the second pixel 32B, ie these pixels 32A, 32B have one substrate 15 in common.
The concave-convex structure on the base material 15 is, for example, for each of a portion corresponding to the first display region 31A where the first pixels 32A are located and a portion corresponding to the second display region 31B where the second pixels 32B are located. , is formed by performing lithography or dry etching. In order to change the height h1 of the convex portion 15a, the etching time should be changed.
The multilayer film layer 16 is simultaneously formed by the same process for the portion corresponding to the first display region 31A and the portion corresponding to the second display region 31B.
When the first display region 31A and the second display region 31B are in contact with each other, the multilayer film layer 16 is continuous between the first pixels 32A and the second pixels 32B.

It should be noted that making the hues exhibited by the first pixels 32A and the second pixels 32B different means that the first pixels 32A and the second pixels 32B have different materials, film thicknesses, etc. of the layers constituting the multilayer film layer 16. It is also possible by making them different. However, if the structure of the multilayer film layer 16 is different for each of the display regions 31A and 31B, masking of the region and film formation of the high refractive index layer 16a and the low refractive index layer 16b may be repeated for each of the display regions 31A and 31B. required and complicates the manufacturing process. As a result, an increase in manufacturing cost and a decrease in yield are caused. Moreover, since it is difficult to mask a very small area, there is a limit to the formation of fine images.

On the other hand, with the configuration of the display 30, it is possible to simultaneously form the multilayer film layer 16 on the portion corresponding to the first display region 31A and the portion corresponding to the second display region 31B. Therefore, the load required for manufacturing the display 30 is reduced. In addition, since it is easier to vary the height h1 of the convex portion 15a for each minute area compared to masking a minute area, the display areas 31A and 31B can be made smaller to form a finer image. You can also

In order to change the hue by changing the height h1 of the convex portion 15a with the structure of the multilayer film layer 16 being the same between the first pixel 32A and the second pixel 32B, the multilayer film layer 16 is formed as follows. It is preferable to configure as follows. That is, when the multilayer film layer 16 is laminated on a flat surface, the peak wavelength of the reflected light from the multilayer film layer 16 is the wavelength of the light with the hue that causes the first pixel 32A to develop a color, and the wavelength of the light that causes the second pixel 32B to develop a color. It is preferable to configure the multilayer film layer 16 so as to be positioned between the wavelength of the light of the hue.

By changing the height h1 of the convex portion 15a, the shape of each layer constituting the multilayer film layer 16 is changed, the optical path length is changed, and the wavelength range of the light efficiently scattered by the concave-convex structure is changed. It is thought that the hue visually recognized by the coloring structure changes due to such a phenomenon or the like.
Further, when the configuration of the coloring structure 22, that is, the configuration in which the resin layer 17 laminated on the base material 15 has an uneven structure, is applied to the configuration of the pixels 32A and 32B, the uneven structure is, for example, , is formed as follows. That is, by using a nanoimprint method, a mold is used in which the height of the unevenness is changed in the portions corresponding to the respective display regions 31A, 31B, and the uneven structure of the resin layer 17 of each of the pixels 32A, 32B is formed at the same time.

Such a mold may be formed by performing lithography or dry etching for each portion corresponding to the display regions 31A and 31B. Further, for example, according to the following method, it is possible to form the mold more simply. That is, the dose of the charged particle beam irradiated to the resist used in the charged particle beam lithography is changed for each of the display regions 31A and 31B, and the development is performed so that unevenness of desired height is formed in each of the display regions 31A and 31B. A resist pattern is formed by adjusting the time. A nickel mold is obtained by forming a metal layer such as nickel on the surface of the resist pattern by electroforming and then dissolving the resist.

The number of display areas included in the display body 30, that is, the number of display areas in which the pixels configured by the color-developing structures are arranged and exhibit colors of different hues is not particularly limited. The number of display areas may be one, or three or more. Furthermore, the display area only needs to include display elements composed of coloring structures, and the display elements are not limited to pixels, which are the minimum repeating unit for forming a raster image. may be a region connecting the anchors of
In addition, as the structure of the display element, any structure can be applied as long as it is the structure of the above-described color-developing structure. , a protective layer, an antireflection layer, an adhesive layer, and the like can be provided.

<Color-developing sheet and molding>
A second application example of the coloring structure is a form in which the coloring structure is used in a coloring sheet. A color-developing sheet is a sheet composed of a color-developing structure, and is fixed to an adherend for decoration or the like. A molded article is composed of the coloring sheet and the adherend.
The shape and material of the adherend are not particularly limited. It is fixed to the surface of the adherend by using a laminate decoration method such as TOM).

The film insert method is a method of integrating an adherend and a coloring sheet by performing injection molding in a state in which a coloring sheet formed by thermal vacuum molding is placed in a mold. The in-mold lamination method is a method in which the processes from thermal vacuum molding of a coloring sheet to formation of an adherend by injection molding and integration with the coloring sheet are all performed in the same mold. The three-dimensional overlay lamination method is a method of integrating an adherend and a coloring sheet by utilizing the air pressure difference in an airtight space vertically separated by a coloring sheet.

As the color-developing structure constituting the color-developing sheet, any of the above-described color-developing structures can be applied. However, since the color-developing sheet is used so as to be arranged along the surface of the adherend, the color-developing structure preferably has the property of being easily deformed into a shape that follows the surface of the adherend. From this point of view, the configuration of the coloring structure 22, that is, the configuration in which the resin layer 17 laminated on the base material 15 has an uneven structure, has a high degree of freedom regarding materials that can be used as the base material 15. Therefore, it is preferable.

When the coloring sheet is fixed to a resin-made adherend by using the laminate decoration method, the substrate 15 deforms following the adherend during heating for integration with the adherend. Thus, the base material 15 is made of a thermoplastic resin. Examples of thermoplastic resins include polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene copolymer (ABS resin), polymethyl methacrylate (PMMA), polyethylene (PE), polypropylene (PP), polycarbonate (PC). , nylon (PA), and the like. From the viewpoint that the coloring sheet easily follows the adherend, the thickness of the base material 15 is preferably as small as possible.

Similarly, in the base material 15 of FIG. 1 as well, it is desirable from the viewpoint of fixation to the adherend that the substrate 15 has the property of being easily deformed into a shape that follows the surface of the adherend. Any resin such as a thermoplastic resin or a thermosetting resin can be used as long as the base material 15 has the property of being easily deformed into a shape that follows the surface of the adherend. In addition to the above, it is also possible to fix by sandwich lamination or dry lamination.
If the base material 15 has adhesiveness, it can be easily pasted onto a base material such as paper.

As shown in FIG. 9 , the coloring structure 24 constituting the coloring sheet 40 preferably has an adhesive layer 18 on the side opposite to the multilayer film layer 16 . The adhesive layer 18 has a function of adhering the coloring sheet 40 and an adherend. In FIG. 9, as the coloring structure 24 constituting the coloring sheet 40, a coloring structure having a configuration in which the resin layer 17 laminated on the base material 15 has the uneven structure of the second structure is applied. example.
Not limited to the above, in FIG. 1 as well, an adhesive layer may be applied to the surface of the substrate 15 opposite to the concave-convex structure, that is, the surface without the convex portions 15a, 15c and concave portions 15b.

When the color-developing sheet is fixed to a resin adherend using a lamination decoration method, the adhesive layer 18 exhibits an adhesive function when heated for integration with the adherend. Layer 18 is preferably heat-sealable. Examples of the heat-sealing agent forming the adhesive layer 18 include thermoplastic resins such as polyethylene, polyvinyl acetate, acrylic resin, polyamide, polyester, polypropylene, and polyurethane.
The adhesive layer 18 is formed using a known coating method such as an inkjet method, a spray method, a bar coating method, a roll coating method, a slit coating method, a gravure coating method, or the like. Although the film thickness of the adhesive layer 18 is not particularly limited, it is preferably, for example, about 2 μm or more and 200 μm or less.

As shown in FIG. 10, the coloring sheet 40 configured as described above is fixed to the adherend 51 so that the adhesive layer 18 is in contact with the adherend 51 . That is, in the formed body 50 in which the coloring sheet 40 is fixed to the adherend 51 , the adherend 51 is positioned on the side where the multilayer film layer 16 faces outward and the substrate 15 is positioned. The multilayer film layer 16 of the coloring sheet 40 is observed from the position side.
Note that the adhesive layer 18 may be formed on the multilayer film layer 16 or may be formed as a protective layer on the multilayer film layer 16 .
The coloring structure 24 constituting the coloring sheet 40 may have an antireflection layer. As for the structure of the coloring sheet, any structure can be applied as long as it has the structure of the coloring structure described above.

As described above, according to the above embodiment, the following effects can be obtained.
(1) In the color-developing structure, the uneven layer contains inorganic particles having a particle diameter of 23% or less of the line width in the first direction in an amount of 3% by mass or more and 25% by mass or less based on the solid content constituting the uneven layer.
According to this configuration, the light transmittance of the uneven layer can be suppressed by the scattering effect of the particles and the absorption effect of the transmitted light. By lowering the light transmittance of the uneven layer, it is possible to prevent the hue from changing after long-term storage of the color-developing structure.
The light that has passed through the multilayer film layer 16 and the uneven layer passes through the interface between the uneven layer and the underlying layer, such as the interface between the resin layer 17 and the base material 15 in FIG. It may be partially reflected at the interface and reduce visibility. It is also possible to prevent deterioration of visibility by containing inorganic particles, reducing light transmittance, and scattering light.

Moreover, in order to obtain the concavo-convex layer easily and inexpensively, it is desirable to produce it by a nanoimprint method. If the particle size and the addition amount are within the above ranges, it is possible to prevent the particles from falling off during the production by the nanoimprint method, and to prevent the mold from being contaminated. Since molds are expensive, preventing contamination can help reduce costs. If the particle size and amount are within the above range, it is possible to prevent contamination due to falling off from the mold and brittleness of the coating film.
Furthermore, the adhesiveness of the uneven layer is improved, and the coloring structure can be easily attached to the adherend, although the adhesive strength is inferior to that in the case of using an adhesive layer.

(2) The particle size of the inorganic particles contained in the uneven layer is preferably 3% or more of the line width in the first direction. According to this configuration, the scattering effect of the particles and the absorption effect of transmitted light can be sufficiently obtained, and it is possible to prevent hue change after long-term storage of the coloring structure.

(3) If the concave-convex layer contains carbon black, the concave-convex layer can absorb light in a wide wavelength range in the visible light region, so that the light transmittance can be further suppressed, and the weather resistance is also good. be. As a result, hue change after long-term storage of the coloring structure can be further prevented. Since it is possible to prevent reflection at the interface between the uneven layer and the underlying layer in contact therewith, it is also possible to prevent deterioration in visibility.

(4) If the concave-convex layer contains titanium black, the concave-convex layer can absorb light in a wide wavelength range in the visible light region, so that the light transmittance can be further suppressed. Therefore, it is possible to further prevent hue change after long-term storage of the coloring structure. Since it is possible to prevent reflection at the interface between the uneven layer and the underlying layer in contact therewith, it is also possible to prevent deterioration in visibility. Since titanium black is transparent to ultraviolet light, it is possible to form an uneven layer by photonanoimprinting.

(5) If the visible light transmittance with respect to incident light is 15% or less, it is possible to prevent reflection at the interface between the uneven layer and the underlying layer in contact with it, thereby preventing deterioration in visibility.

(6) If the resin layer 17 covering the surface of the base material 15 is formed with an uneven structure, the degree of freedom in selecting the material for the base material 15 is increased. It is possible to apply a nanoimprint method suitable for forming unevenness.

(7) By providing the adhesive layer 18, it can be easily fixed to the adherend. If the adhesive layer 18 has a heat-sealing property, the adhesive layer 18 is attached to the adherend 51 when the coloring sheet 40 is fixed to the surface of the adherend 51 using the lamination decoration method. By bringing the coloring sheet 40 and the adherend 51 into contact with each other, the coloring sheet 40 and the adherend 51 are preferably bonded. Therefore, a structure suitable for the coloring sheet 40 fixed to the surface of the adherend 51 using the lamination decoration method is realized.

(8) Since the display has a plurality of display elements, it can be used in all fields as a display.

(9) According to the manufacturing method in which the uneven structure of the uneven layer is formed using the nanoimprint method, a fine uneven structure can be suitably and easily formed. If the manufacturing method uses the optical nanoimprinting method or the thermal nanoimprinting method as the nanoimprinting method, the formation of the concave-convex structure by the nanoimprinting method can be suitably and simply achieved.

[Modification]
The above embodiment can be implemented with the following modifications.
- The adhesive layer 18 may be provided on the multilayer film layer 16 . However, when the permeability of the uneven layer is low, it is difficult to visually recognize the multilayer film layer 16 from the uneven layer side. desirable.
- The substrate 15 may be attached to another substrate or material. For example, another base material can be pasted under the base material 15 via an adhesive layer. Performance that cannot be achieved with one type of base material can be achieved by combining multiple types of materials.
- Functional layers such as a plurality of protective layers may be provided on the multilayer film layer 16 . By combining a plurality of layers, it is possible to express performance that is difficult to impart with a single layer. However, if the protective layer deteriorates due to storage, the hue will change, so there are restrictions on materials and the like.

The pixels included in the display 30 may include pixels in which the directions in which the uneven structure of the uneven layer extends on the virtual plane are different from each other. Specifically, the second direction Dy, which is the direction in which a convex portion extends in an arbitrary pixel, and the second direction Dy, which is the direction in which a convex portion extends in a pixel different from this pixel, are different directions, For example, these directions may be perpendicular to each other. According to such a configuration, it is possible to change the direction in which the reflected light from the multilayer film layer 16 is diffused, depending on the pixel, and various images can be expressed.

Since the multilayer film layer 16 is also formed on the side surfaces of the projections of the uneven layer, the width of the projections of the uneven structure in the multilayer film layer 16 is slightly wider than the width of the projections of the uneven layer. In the portion where the pixels with the uneven structure extending in different directions are adjacent to each other, the portions of the multilayer film layer 16 that are widened as described above are connected between the convex parts with the different extending directions, and the uneven structure in the multilayer film layer 16 collapses. occurs, it becomes difficult to obtain desired color development from each pixel in a desired direction. Therefore, it is preferable that the uneven layer is provided with a region in which the uneven structure is not formed between the pixels whose extending directions of the uneven structure are different from each other. Further, even between pixels having an uneven structure extending in the same direction, the uneven layer may have a region where unevenness is not formed. Structural collapse is suppressed at the edges of the pixels, making it easier to obtain desired color development from the entirety of each pixel. It is preferable that the width of the region provided between the pixels where the unevenness is not formed is, for example, 1/2 or more of the film thickness of the multilayer film layer 16 .

- The convex portion that constitutes the concave-convex structure of the concave-convex layer may have a configuration in which the width in the first direction Dx gradually decreases from the base toward the top. According to such a configuration, the multilayer film layer 16 is easily formed on the convex portion. In this case, the length d1 and the length d3 in the first direction Dx are defined by the pattern formed by the bottom surfaces of the protrusions.
The figure constituting the pattern formed by the projected image of the projection 15a in the first structure of the concave-convex structure in the concave-convex layer and the pattern formed by the projected image of the first convex element 15Ea in the second structure , but not limited to rectangles. The figures forming these patterns may be ellipses or the like, and in short, any figure element having a shape whose length along the second direction Dy is greater than or equal to the length along the first direction Dx. Just do it. It is sufficient that the length d1 in the first direction Dx and the length d2 in the second direction Dy of the graphic element satisfy the various conditions described in the description of the first structure.

- The outermost layer of the multilayer film layer 16, that is, the layer forming the outermost surface of the multilayer film layer 16 opposite to the uneven layer may function as a protective layer. The layer that functions as a protective layer should be able to suppress, from at least one point of view, changes that make it difficult to obtain the desired color in the coloring structure, such as deformation and deterioration of the uneven structure in the layers below the protective layer. .

Specifically, the outermost layer in the multilayer film layer 16 functions as a protective layer by having properties different from those of the layers other than the outermost layer in the multilayer film layer 16 . Such properties may be structural, chemical or physical properties, such as hardness, thickness, roughness height, water repellency, and the like. For example, if the hardness of the outermost layer is greater than that of the other layers, or the thickness of the outermost layer is greater than that of the other layers, the outermost layer will be more resistant to impact than the other layers. The concave-convex structure of the lower layer is protected. In addition, if the height of the unevenness in the outermost layer is smaller than that of the other layers, that is, if the outermost layer has a higher flatness than the other layers, the height of the unevenness on the surface of the multilayer film layer 16 becomes small. This makes it difficult for the impact to cause uneven deformation. Therefore, the concave-convex structure of the lower layer than the outermost layer is protected.

Even if the outermost layer in the multilayer film layer 16 has different characteristics from the layers other than the outermost layer, the multilayer film layer 16 as a whole has a surface shape following the uneven structure of the uneven layer, that is, the uneven layer The multilayer film layer 16 has irregularities arranged corresponding to the arrangement of the irregularities in the irregular structure, and the reflectance of the light in a specific wavelength region of the incident light incident on the multilayer film layer 16 is different in other wavelength regions. is configured to be higher than the light reflectivity of the

Next, the coloring structure and the manufacturing method thereof described above will be described using specific examples.

<Example 1>
Example 1 is a display in which a coloring structure is applied to pixels. A pixel included in the display body of Example 1 is composed of a color-developing structure in which an uneven structure having a first structure is formed on a base material.
First, a mold, which is an intaglio used in photo-nanoimprinting, was prepared. Specifically, since light with a wavelength of 365 nm was used as light for irradiation in the photo-nanoimprinting method, synthetic quartz, which transmits light with this wavelength, was used as a material for the mold. When forming the mold, first, a film made of chromium (Cr) was formed on the surface of the synthetic quartz substrate by sputtering, and an electron beam resist pattern was formed on the Cr film by electron beam lithography. The formed pattern is a pattern consisting of a set of a plurality of rectangles shown in FIG. The area to be a pixel is a square with a side of 130 mm, the length of the rectangle in the first direction is 350 nm, and the length of the rectangle in the second direction is normalized with an average value of 2300 nm and a standard deviation of 560 nm. A length selected from a distribution. In the pattern, the plurality of rectangles are arranged so as not to overlap in the first direction. The resist used was of positive type and had a film thickness of 200 nm.

Next, the Cr film exposed from the resist was etched by plasma generated by applying a high frequency to a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ). Subsequently, the region of the synthetic quartz substrate exposed from the resist and the Cr film was etched by plasma generated by applying high frequency to ethane hexafluoride gas. The synthetic quartz substrate thus etched had a depth of 70 nm. The remaining resist and Cr film were removed, and OPTOOL HD-1100 (manufactured by Daikin Industries, Ltd.) was applied as a release agent to obtain a mold 1 having an uneven structure.

Subsequently, a coating liquid was prepared for transferring the concave-convex structure from the mold. It should be noted that "parts" in the text are based on mass unless otherwise specified. The coating liquid from which the initiator was removed was stirred with a 0.1 mm zirconia ball at 200 rpm for 3 hours using a ball mill. After stirring, diluted initiator was added and stirred for 3 minutes. Then, the following coating liquid-1 was obtained by filtering and removing the zirconia balls.

"Coating liquid -1"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
61.8 parts by mass Silica (trade name: QSG-80, manufactured by Shin-Etsu Chemical Co., Ltd.) 2.0 parts by mass Particle size: 80 nm, particle size relative to line width: 23%, addition amount: 3% by mass
Methyl ethyl ketone 33.8 parts by mass Photoradical polymerization initiator (trade name: Omnirad 1173, manufactured by IGM)
Methyl ethyl ketone dilution solid content 50% 2.4 parts by mass (solid content 1.2 parts by mass)

The coating liquid-1 was applied on the mold 1 to a thickness of 50 μm, dried at 80° C. for 3 minutes, and cured by irradiating light of 365 nm at 3000 mJ/cm ² in a nitrogen purge environment. After that, it was separated from the mold. A TiO ₂ film with a thickness of 50 nm as a high refractive index layer and a SiO ₂ film with a thickness of 85 nm as a low refractive index layer are alternately formed by vacuum deposition on the uneven surface, Five sets of high refractive index layers and low refractive index layers, that is, a multilayer film layer having 10 layers were formed.
A black backing paper was placed under the color-developing structure of Example 1 and observed from the side where the multilayer film layer was located.

<Example 2>
A coloring structure of Example 2 was obtained in the same manner as in Example 1, except that the coating liquid was changed to the following coating liquid-2. A black backing paper was placed under the color-developing structure of Example 2 and observed from the side where the multilayer film layer was located.

"Coating liquid -2"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
36.8 parts by mass Silica (trade name: QSG-80, manufactured by Shin-Etsu Chemical Co., Ltd.) 12.5 parts by mass Particle size: 80 nm, particle size relative to line width: 23%, amount added: 25% by mass
Methyl ethyl ketone 49.3 parts by mass Photoradical polymerization initiator (trade name: Omnirad 1173, manufactured by IGM)
Methyl ethyl ketone dilution Nv50% 1.4 parts by mass (solid content 0.7 parts by mass)

<Example 3>
First, a mold, which is an intaglio used in photo-nanoimprinting, was prepared. Specifically, since light with a wavelength of 365 nm was used as light for irradiation in the photo-nanoimprinting method, synthetic quartz, which transmits light with this wavelength, was used as a material for the mold. When forming the mold, first, a film made of chromium (Cr) was formed on the surface of the synthetic quartz substrate by sputtering, and an electron beam resist pattern was formed on the Cr film by electron beam lithography. The formed pattern is a pattern consisting of a set of a plurality of rectangles shown in FIG. The pixel region is a square with a side of 130 mm, the length of the rectangle in the first direction is 460 nm, and the length of the rectangle in the second direction is normalized with an average value of 3600 nm and a standard deviation of 640 nm. A length selected from a distribution. In the pattern, the plurality of rectangles are arranged so as not to overlap in the first direction. The resist used was of positive type and had a film thickness of 200 nm.

Next, the Cr film exposed from the resist was etched by plasma generated by applying a high frequency to a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ). Subsequently, the region of the synthetic quartz substrate exposed from the resist and the Cr film was etched by plasma generated by applying high frequency to ethane hexafluoride gas. The synthetic quartz substrate thus etched had a depth of 70 nm. The remaining resist and Cr film were removed, and OPTOOL HD-1100 (manufactured by Daikin Industries, Ltd.) was applied as a release agent to obtain a mold 2 having an uneven structure.

Subsequently, a coating liquid was prepared for transferring the concave-convex structure from the mold. The coating liquid from which the initiator was removed was stirred with a 0.1 mm zirconia ball at 200 rpm for 3 hours using a ball mill. After stirring, diluted initiator was added and stirred for 3 minutes. Then, the following coating liquid-3 was obtained by filtering and removing the zirconia balls.

"Coating liquid -3"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
61.8 parts by mass Silica (trade name: EP-M2130Y, solid content 30%, manufactured by Nissan Chemical Industries) 6.5 parts by mass Particle size: 12 nm, particle size relative to line width: 3%, addition amount: 3% by mass
Methyl ethyl ketone 29.3 parts by mass Photoradical polymerization initiator (trade name: Omnirad 1173, manufactured by IGM)
Methyl ethyl ketone dilution Nv50% 2.4 parts by mass (solid content 1.2 parts by mass)

The coating liquid-3 was applied on the mold 2 to a thickness of 50 μm, dried at 80° C. for 3 minutes, and cured by irradiating light of 365 nm at 3000 mJ/cm ² in a nitrogen purge environment. After that, it was separated from the mold. A TiO ₂ film with a thickness of 80 nm as a high refractive index layer and a SiO ₂ film with a thickness of 110 nm as a low refractive index layer are alternately formed by vacuum deposition on the uneven surface, Five sets of high refractive index layers and low refractive index layers, that is, a multilayer film layer having 10 layers were formed.
Thus, a coloring structure of Example 3 was obtained. A black backing paper was placed under the coloring structure of Example 3 and observed from the side where the multilayer film was located.

<Example 4>
First, a mold, which is an intaglio used in photo-nanoimprinting, was prepared. Specifically, since light with a wavelength of 365 nm was used as light for irradiation in the photo-nanoimprinting method, synthetic quartz, which transmits light with this wavelength, was used as a material for the mold. When forming the mold, first, a film made of chromium (Cr) was formed on the surface of the synthetic quartz substrate by sputtering, and an electron beam resist pattern was formed on the Cr film by electron beam lithography. The formed pattern is a pattern consisting of a set of a plurality of rectangles shown in FIG. The area to be a pixel is a square with a side of 130 mm, the length of the rectangle in the first direction is 300 nm, and the length of the rectangle in the second direction is normalized with an average value of 2000 nm and a standard deviation of 500 nm. A length selected from a distribution. In the pattern, the plurality of rectangles are arranged so as not to overlap in the first direction. The resist used was of positive type and had a film thickness of 200 nm.

Next, the Cr film exposed from the resist was etched by plasma generated by applying a high frequency to a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ). Subsequently, the region of the synthetic quartz substrate exposed from the resist and the Cr film was etched by plasma generated by applying high frequency to ethane hexafluoride gas. The synthetic quartz substrate thus etched had a depth of 70 nm. The remaining resist and Cr film were removed, and OPTOOL HD-1100 (manufactured by Daikin Industries, Ltd.) was applied as a release agent to obtain a mold 3 having an uneven structure.
Subsequently, a coating liquid was prepared for transferring the concave-convex structure from the mold. The coating liquid from which the initiator was removed was stirred with a 0.1 mm zirconia ball at 200 rpm for 3 hours using a ball mill. After stirring, diluted initiator was added and stirred for 3 minutes. Thereafter, the following coating liquid-4 was obtained by filtering and removing the zirconia balls.

"Coating liquid -4"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
60.0 parts by mass carbon black (trade name: Denka Black Li Li-250, manufactured by Denka)
2.0 parts by mass Particle size: 35 nm, Particle size relative to line width: 12%, Addition amount: 3% by mass
Methyl ethyl ketone 32.0 parts by mass Azo polymerization initiator (trade name: 2,2'-Azobis-2-methylbutyronitrile, manufactured by Otsuka Chemical)
Methyl ethyl ketone dilution Nv50% 6.0 parts by mass (solid content 3.0 parts by mass)

The coating liquid-4 was applied on the mold 3 to a thickness of 50 μm and cured at 120° C. for 4 hours. After that, it was separated from the mold. A TiO ₂ film with a thickness of 40 nm as a high refractive index layer and a SiO ₂ film with a thickness of 75 nm as a low refractive index layer are alternately formed by vacuum deposition on the uneven surface, Five sets of high refractive index layers and low refractive index layers, that is, a multilayer film layer having 10 layers were formed.
Thus, a coloring structure of Example 4 was obtained.
When the coloring structure of Example 4 was observed from the side where the multilayer film was located, a blue color was confirmed with good visibility in the region where the pixels were located.

<Example 5>
Using the following coating liquid-5 prepared by the same kneading method as in Example 1, it was coated on mold 2 to a thickness of 50 μm and cured at 120° C. for 4 hours. After that, it was separated from the mold. A TiO ₂ film with a thickness of 80 nm as a high refractive index layer and a SiO ₂ film with a thickness of 110 nm as a low refractive index layer are alternately formed by vacuum deposition on the uneven surface, Five sets of high refractive index layers and low refractive index layers, that is, a multilayer film layer having 10 layers were formed.
Thus, a coloring structure of Example 5 was obtained. When the coloring structure of Example 5 was observed from the side where the multilayer film was located, red color was confirmed with good visibility in the region where the pixels were located.

"Coating liquid -5"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
60.0 parts by mass Carbon black (trade name: Asahi #95, manufactured by Asahi Carbon) 2.0 parts by mass Particle size: 17 nm, Particle size relative to line width: 4%, Addition amount: 3% by mass
Methyl ethyl ketone 32.0 parts by mass Azo polymerization initiator (trade name: 2,2'-Azobis-2-methylbutyronitrile, manufactured by Otsuka Chemical)
Methyl ethyl ketone dilution Nv50% 6.0 parts by mass (solid content 3.0 parts by mass)

<Example 6>
Using the coating liquid-6 prepared by the same kneading method as in Example 1, 50 μm is applied on the mold 3, dried at 80 ° C. for 3 minutes, and then 3000 mJ / cm ² of light of 365 nm in a nitrogen purge environment. Cured by irradiation. After that, it was separated from the mold. A TiO ₂ film with a thickness of 40 nm as a high refractive index layer and a SiO ₂ film with a thickness of 75 nm as a low refractive index layer are alternately formed by vacuum deposition on the uneven surface, Five sets of high refractive index layers and low refractive index layers, that is, a multilayer film layer having 10 layers were formed.
Thus, a coloring structure of Example 6 was obtained. When the coloring structure of Example 6 was observed from the side where the multilayer film was located, a blue color was confirmed with good visibility in the region where the pixels were located.

"Coating liquid -6"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
61.8 parts by mass Titanium black (trade name: 13M-T, manufactured by Mitsubishi Materials) 2.0 parts by mass Particle size: 67 nm, particle size relative to line width: 22%, addition amount: 3% by mass
Methyl ethyl ketone 33.8 parts by mass Photoradical polymerization initiator (trade name: Omnirad 1173, manufactured by IGM)
Methyl ethyl ketone dilution solid content 50% 2.4 parts by mass (solid content 1.2 parts by mass)

<Example 7>
Example 7 is a coloring sheet to which a coloring structure is applied, and a molding using this coloring sheet. The color-developing sheet of Example 7 is composed of a color-developing structure in which a concave-convex structure having a second structure is formed on a resin layer on a substrate.
First, a mold, which is an intaglio used in photo-nanoimprinting, was prepared. Specifically, since light with a wavelength of 365 nm was used as light for irradiation in the photo-nanoimprinting method, synthetic quartz, which transmits light with this wavelength, was used as a material for the mold. When forming the mold, first, a film made of chromium (Cr) was formed on the surface of the synthetic quartz substrate by sputtering, and an electron beam resist pattern was formed on the Cr film by electron beam lithography. The formed pattern is a pattern consisting of a set of a plurality of rectangles shown in FIG. The length of the rectangle in the first direction is 350 nm and the length of the rectangle in the second direction is selected from a normal distribution with a mean value of 2300 nm and a standard deviation of 560 nm. In the pattern, the plurality of rectangles are arranged so as not to overlap in the first direction. The resist used was of positive type and had a film thickness of 200 nm.

Subsequently, the Cr film exposed from the resist was etched by plasma generated by applying a high frequency to a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ). Subsequently, the region of the synthetic quartz substrate exposed from the resist and the Cr film was etched by plasma generated by applying high frequency to ethane hexafluoride gas. The synthetic quartz substrate thus etched had a depth of 70 nm. By removing the remaining resist and Cr film, a synthetic quartz substrate having an uneven structure corresponding to the first structure was obtained.

Next, a Cr film was formed by sputtering on the surface of the synthetic quartz substrate on which the uneven structure was formed, and an electron beam resist pattern was formed on the Cr film by electron beam lithography. The formed pattern is a pattern consisting of a plurality of belt-like regions shown in FIG. A rectangle having a length of 350 nm in the first direction, a length of 94 μm in the second direction, and a length of 40 μm in the first direction and 94 μm in the second direction For each region, the band-shaped regions are arranged with an arrangement interval in the first direction having an average value of 1.5 μm and a standard deviation of 0.5 μm. The electron beam resist used was a positive type, and the film thickness was 200 nm.

Subsequently, the Cr film exposed from the resist was etched by plasma generated by applying a high frequency to a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ). Subsequently, the region of the synthetic quartz substrate exposed from the resist and the Cr film was etched by plasma generated by applying high frequency to ethane hexafluoride gas. The synthetic quartz substrate thus etched had a depth of 65 nm. After removing the remaining resist and Cr film, the surface of the synthetic quartz substrate was coated with OPTOOL HD-1100 (manufactured by Daikin Industries, Ltd.) as a release agent. As a result, a mold having an uneven structure corresponding to the second structure was obtained.

Next, the following coating liquid-7 was kneaded in the same manner as in Example 1 on the surface of a polyester film (Cosmoshine A4100, manufactured by Toyobo) that had been subjected to an easy-adhesion treatment on one side. was applied, the surface of the mold on which the unevenness was formed was pressed against this resin, and 3000 mJ/cm ² of light of 365 nm was irradiated from the back side of the mold. After the photocurable resin was cured by irradiation with this light, the polyester film and the resin layer were peeled off from the mold. As a result, a polyester film was obtained as a base material on which a resin layer having a concave-convex structure of the second structure was laminated. In Example 7, since the coating liquid is sandwiched between the mold and the polyester film, curing inhibition is unlikely to occur, and thus curing can be performed without nitrogen purge.

"Coating liquid -7"
EO-modified bisphenol A diacrylate (trade name: Light Acrylate BP-10EA, manufactured by Kyoeisha Chemical)
47.5 parts by mass N-vinyl-2-pyrrolidone 47.5 parts by mass Silica (trade name: QSG-80, manufactured by Shin-Etsu Chemical) 3.0 parts by mass Particle size: 80 nm, particle size relative to line width: 23%, addition Amount: 3% by mass
Photoradical polymerization initiator (trade name: Omnirad 1173, manufactured by IGM)
1.9 parts by mass

Next, a TiO ₂ film as a high refractive index layer with a thickness of 50 nm and a low refractive index layer with a thickness of 85 nm were applied to the uneven surface of the obtained laminate of the substrate and the resin layer by vacuum deposition. SiO ₂ films as refractive index layers were alternately deposited to form a multi-layered film having 5 sets of high refractive index layers and low refractive index layers, that is, 10 layers.
Subsequently, on the surface of the base material opposite to the resin layer, that is, on the surface of the polyester film on which the resin layer is not applied, about 4% by mass of carbon nanotube powder is mixed using a bar coating method to form an acrylic resin. A resin was applied and the applied layer was dried at 80° C. for 2 minutes to form an adhesive layer having a thickness of about 50 μm. Thus, a coloring sheet of Example 7 was obtained.

A molding of Example 7 was obtained by integrating the coloring sheet of Example 7 with a polycarbonate adherend using a three-dimensional overlay lamination method. Specifically, the adhesive layer of the coloring sheet was placed in a molding machine with the adhesive layer facing the adherend, and after the inside of the molding machine was evacuated, the molding machine was heated to 160° C. to bring the coloring sheet and the adherend into contact. In this state, the coloring sheet and the adherend were integrated by applying pressure from the side of the coloring sheet to atmospheric pressure. After that, by cutting off unnecessary portions of the coloring sheet, a molding of Example 7 decorated with the coloring sheet was obtained.
When the molded product of Example 7 was observed, a glossy bluish-green color was confirmed with good visibility in the portion where the coloring sheet was positioned.

<Comparative Example 1>
A coloring structure of Comparative Example 1 was obtained in the same manner as in Example 1, except that the coating liquid was changed to the following coating liquid-8. A black backing paper was placed under the coloring structure of Comparative Example 1 and observed from the side where the multilayer film layer was located.

"Coating liquid -8"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
63.7 parts by mass Methyl ethyl ketone 33.7 parts by mass Radical photopolymerization initiator (trade name: Omnirad 1173, manufactured by IGM)
Methyl ethyl ketone dilution solid content 50% 2.6 parts by mass (solid content 1.3 parts by mass)

<Comparative Example 2>
A coloring structure of Comparative Example 2 was obtained in the same manner as in Example 1, except that the coating liquid was changed to the following coating liquid-9. A black backing paper was placed under the coloring structure of Comparative Example 2 and observed from the side where the multilayer film layer was located.

"Coating liquid -9"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
34.3 parts by mass Silica (trade name: QSG-80, manufactured by Shin-Etsu Chemical Co., Ltd.) 15.0 parts by mass Particle size: 80 nm, particle size relative to line width: 23%, amount added: 30% by mass
Methyl ethyl ketone 49.3 parts by mass Photoradical polymerization initiator (trade name: Omnirad 1173, manufactured by IGM)
Methyl ethyl ketone dilution solid content 50% 1.4 parts by mass (solid content 0.7 parts by mass)

<Comparative Example 3>
A coloring structure of Comparative Example 3 was obtained in the same manner as in Example 6, except that the coating liquid was changed to the following coating liquid-10. A black backing paper was placed under the coloring structure of Comparative Example 3 and observed from the side where the multilayer film layer was located.

"Coating liquid -10"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
62.5 parts by mass Silica (trade name: QSG-80, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.3 parts by mass Particle size: 80 nm, particle size relative to line width: 23%, addition amount: 2% by mass
Methyl ethyl ketone 49.3 parts by mass Photoradical polymerization initiator (trade name: Omnirad 1173, manufactured by IGM)
Methyl ethyl ketone dilution solid content 50% 1.4 parts by mass (solid content 0.7 parts by mass)

<Comparative Example 4>
Example 4 except that the coating liquid was changed to the above coating liquid-1, the curing conditions of the coating liquid were dried at 80 ° C. for 3 minutes, and then the light of 365 nm was changed to 3000 mJ / cm ² irradiation in a nitrogen purge environment. A coloring structure of Comparative Example 4 was obtained in the same manner as above. A black backing paper was placed under the coloring structure of Comparative Example 4 and observed from the side where the multilayer film layer was located.

<Comparative Example 5>
A colored structure of Comparative Example 5 was obtained in the same manner as in Example 4, except that the coating liquid was changed to coating liquid-11 below and the curing conditions of the coating liquid were changed to 120° C. for 4 hours. When Comparative Example 5 was observed from the side where the multilayer film layer was located, a blue color was confirmed with good visibility in the region where the pixels were located.

"Coating liquid -11"
Urethane acrylic resin (trade name: UV-7000B, manufactured by Nippon Synthetic Chemical Industry)
35.7 parts by mass carbon black (trade name: HTC #SL SRF-LM, manufactured by Shin Nikka Carbon)
12.5 parts by mass Particle size: 75 nm, Particle size relative to line width: 25%, Addition amount: 3% by mass
Methyl ethyl ketone 48.2 parts by mass Azo polymerization initiator (trade name: 2,2'-Azobis-2-methylbutyronitrile, manufactured by Otsuka Chemical)
Methyl ethyl ketone dilution Nv50% 3.6 parts by mass (solid content 1.8 parts by mass)

"evaluation"
The coloring sheets of Examples 1 to 7 and Comparative Examples 1 to 5 were evaluated for hue change, staining of the mold, and gluing properties as follows. Table 1 shows the evaluation results. As for Example 7, hue change and mold contamination were evaluated in the coloring structure before the adhesive layer was applied.
・[Evaluation of Hue Change]
Using an eye super UV acceleration tester SUV-Wl61 (light source: metal halide lamp, filter: Super UV, manufactured by Iwasaki Electric), light irradiation for 20 hours (65 w / m ² , 63 ° C. 50%), rest for 4 hours (0 w /m ² ) for 24 hours, and the weather resistance test was performed for a total of 1920 hours. The exposed surface was the multilayer film layer side. The hue before and after the test was measured with an ultraviolet-visible-near-infrared spectrophotometer UV3600 (manufactured by Shimadzu Corporation) at an incident angle of 8 degrees in the visible light region of 380 to 780 nm. The spectral reflectance spectrum was divided into XYZ components, converted into the L*a*b* color system, and the degree of color fading before and after the weather resistance test was calculated from the color difference.

Here, according to the following criteria, "○" is judged to be good, "Δ" is judged to be at a practically acceptable level, and "×" is judged to be unsatisfactory.
Judgment criteria ○: ΔE ≤ 3.2 (A class tolerance or more, generally judged to be the same color)
△: 3.2 < ΔE ≤ 6.5 (class B tolerance, can be treated as the same color at the impression level)
×: ΔE ≥ 6.5 (C class tolerance or less)

・[Evaluation of mold contamination]
After producing 50 concave-convex layers from the produced mold, contamination of the mold was determined visually and by a scanning electron microscope.
Evaluation is as follows.
○: Good. There is no clogging of the pattern and almost no adhesion of foreign matter.
(Here, almost no minute foreign matter adheres means that the foreign matter adhered area is less than 2% of the area of the observation range.)
×: Defective. There is clogging in the mold, or there is a lot of foreign matter adhered.

・ [Evaluation of pasting performance]
The surface opposite to the multilayer film layer, ie, the surface on which the multilayer film was not vapor-deposited, was coated with stick glue (solid Arabic, manufactured by Yamato) and pasted on woodfree paper. After observing the state after drying, the film was peeled off and the pasting property was judged.
Evaluation is as follows.
○: Good. On the peeling surface, the high-quality paper is torn.
Δ: level that poses no practical problem.
Some parts are peeled off between the adhesive on the peeling surface and the fine paper.
×: Defective. After drying, some peeling is seen at the edges.
The release surface is mostly peeled off between the glue and the fine paper.

From the results in Table 1, it was found that the color-developing structures of Examples 1 to 7 had little change in hue after long-term storage and scarcely caused contamination of the mold. It was found that the coloring structures of Examples 1 to 6 also had good pasting properties.
It was found that the coloring structures of Examples 4 to 6 and Comparative Example 5 showed particularly small changes in hue. Moreover, good visibility was confirmed even without using a black sheet for the back surface.
Since the coloring structure of Comparative Example 1 did not contain inorganic particles, the hue changed after long-term storage. In the coloring structure of Comparative Example 2, the amount of inorganic particles added was large, so the mold was contaminated. In the coloring structure of Comparative Example 3, since the amount of inorganic particles added was as small as 2%, the hue changed after long-term storage. Since the coloring structures of Comparative Examples 4 and 5 had a large ratio of line width to particle size, the mold was contaminated.

Dx... first direction, Dy... second direction, 10, 11, 12... concavo-convex structure, 15... base material, 15a, 15c... convex parts, 15b... concave parts, 15Ea... first convex element, 15Eb... second Convex element 16 Multilayer film layer 16a High refractive index layer 16b Low refractive index layer 17 Resin layer 18 Adhesive layer 20, 21, 22, 23, 24 Coloring structure 30 Display body 30F Front surface 30R Back surface 31A, 31B Display area 32A, 32B Pixel 30 Color development sheet 40 Molded body 51 Adherend.

Claims (18)

an uneven layer having an uneven structure on its surface;
a multilayer film layer provided on the uneven structure and having a surface shape that follows the uneven structure;
In each layer constituting the multilayer film layer, the refractive index of the adjacent layers is different from each other, and the reflectance of light in a specific wavelength region of the incident light incident on the multilayer film layer is different in other wavelength regions. higher than the light reflectance of
The preset first direction and the second direction orthogonal to the first direction are directions along a virtual plane, which is a virtual plane on which the uneven structure is projected in the thickness direction of the uneven layer,
The pattern formed by the projection image of the projection of the uneven structure on the virtual plane is a pattern consisting of a set of a plurality of graphic elements whose length along the second direction is equal to or greater than the length along the first direction. including
Each of the graphic elements has a length along the first direction equal to or less than a sub-wavelength, and each graphic element has a standard deviation of the length along the second direction of the length along the first direction. greater than the standard deviation,
The uneven layer contains inorganic particles having a particle diameter of 23% or less of the line width in the first direction in an amount of 3% by mass or more and 25% by mass or less with respect to the solid content constituting the uneven layer,
A coloring structure, wherein the uneven layer is a layer containing a urethane acrylic resin, or a layer containing EO-modified bisphenol A diacrylate and N-vinyl-2-pyrrolidone. 2. The coloring structure according to claim 1, wherein the particle size of the inorganic particles contained in the uneven layer is 3% or more of the line width in the first direction. 3. The coloring structure according to claim 1, wherein at least part of the inorganic particles contained in the uneven layer is carbon black. 4. The color-developing structure according to any one of claims 1 to 3, wherein at least part of the inorganic particles contained in the uneven layer is titanium black. 4. The coloring structure according to any one of claims 1 to 3, wherein at least part of the inorganic particles contained in the uneven layer is silica. 6. The coloring structure according to claim 1, wherein the uneven layer has a visible light transmittance of 15% or less with respect to the incident light. 7. The coloring structure according to any one of claims 1 to 6, further comprising an adhesive layer on the surface opposite to the multilayer film layer. The uneven layer is composed of a substrate and a resin layer formed on one surface of the substrate, and the uneven structure is formed on the surface of the resin layer opposite to the substrate. The coloring structure according to any one of claims 1 to 7, characterized by: 9. The coloring structure according to any one of claims 1 to 8, wherein a surface of the multilayer film layer opposite to the uneven layer is exposed. 10. The coloring structure according to any one of claims 1 to 9, wherein the uneven layer is a layer containing a urethane acrylic resin. 10. The coloring structure according to any one of claims 1 to 9, wherein the uneven layer is a layer containing EO-modified bisphenol A diacrylate and N-vinyl-2-pyrrolidone. A display body comprising a plurality of display elements at least on its surface,
A display, wherein the display element is composed of the coloring structure according to any one of claims 1 to 11. a step of forming an uneven layer having an uneven structure on the surface by transferring the unevenness of the intaglio onto a resin using a nanoimprint method;
a step of forming on the uneven structure such that the layers constituting the multilayer film layer are adjacent to each other and have different refractive indices;
A first direction set in advance and a second direction orthogonal to the first direction are directions along a virtual plane, which is a virtual plane on which the uneven structure is projected in the thickness direction of the uneven layer,
In the step of forming the concavo-convex layer, the length along the second direction is equal to or greater than the length along the first direction as the pattern formed on the imaginary plane by the projected image of the projections forming the concavo-convex structure. forming the uneven structure so as to include a pattern consisting of a set of a plurality of graphic elements,
The length of the graphic element along the first direction is sub-wavelength or less, and the standard deviation of the length of the graphic element along the second direction is larger than the standard deviation of the length along the first direction. make it bigger,
The uneven layer is a layer containing a urethane acrylic resin, or a layer containing EO-modified bisphenol A diacrylate and N-vinyl-2-pyrrolidone ,
The uneven layer contains inorganic particles having a particle diameter of 23% or less of the line width in the first direction in an amount of 3% by mass or more and 25% by mass or less based on the solid content constituting the uneven layer. A method for producing a coloring structure. 14. The method for producing a coloring structure according to claim 13 , wherein at least part of the inorganic particles contained in the uneven layer is silica. 15. The method for manufacturing a coloring structure according to claim 13, wherein the uneven layer is a layer containing a urethane acrylic resin. 15. The method for producing a coloring structure according to claim 13, wherein the uneven layer is a layer containing EO-modified bisphenol A diacrylate and N-vinyl-2-pyrrolidone. A method for producing a coloring structure according to any one of claims 1 to 11,
a step of forming an uneven layer having an uneven structure on the surface by transferring the unevenness of the intaglio onto a resin using a nanoimprint method;
a step of forming on the uneven structure such that the layers constituting the multilayer film layer are adjacent to each other and have different refractive indices;
A first direction set in advance and a second direction orthogonal to the first direction are directions along a virtual plane, which is a virtual plane on which the uneven structure is projected in the thickness direction of the uneven layer,
In the step of forming the concavo-convex layer, the length along the second direction is equal to or greater than the length along the first direction as the pattern formed on the imaginary plane by the projected image of the projections forming the concavo-convex structure. forming the uneven structure so as to include a pattern consisting of a set of a plurality of graphic elements,
The length of the graphic element along the first direction is sub-wavelength or less, and the standard deviation of the length of the graphic element along the second direction is larger than the standard deviation of the length along the first direction. Enlarge,
A method for producing a coloring structure, characterized by: 18. The method for producing a coloring structure according to any one of claims 13 to 17 , wherein the nanoimprinting method is a photonanoimprinting method or a thermal nanoimprinting method.

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