Color-forming structure

Abstract

To provide a color development structure body capable of enhancing an intensity of reflectance at a wide observation angle.SOLUTION: A color development structure body 10 includes: a rugged structure layer 30 having a rugged structure on a surface thereof; and a multilayer film layer 40 being a lamination film located on the rugged structure, having a surface shape following the rugged structure, and configured to emit reflectance enhanced by an interference. A plurality of protrusions 31 include a first protrusion 32 and a second protrusion 33. A maximum height Rz2 on a surface of the second protrusion 33 is larger than a maximum height Rz1 on a surface of the first protrusion 32. At least one of the plurality of protrusions 31 neighboring the first protrusion 32 is the second protrusion 33.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a color-developing structure that exhibits structural color. [Background technology]

[0002] Structural colors, often observed in natural organisms such as Morpho butterflies, are visible due to optical phenomena caused by the microscopic structure of an object, such as light diffraction, interference, and scattering. For example, structural colors caused by multilayer interference occur when light is reflected at the interfaces of adjacent thin films and the reflected light interferes with one another. Multilayer interference is one of the principles behind the coloration of Morpho butterfly wings. In Morpho butterfly wings, in addition to multilayer interference, the scattering and diffraction of light occurs due to the minute irregularities on the wing surface, resulting in a vivid blue color that can be seen from a wide viewing angle.

[0003] As a structure for artificially reproducing structural colors like those of Morpho butterfly wings, a structure in which a multilayer film layer is stacked on a fine uneven structure has been proposed, as described in Patent Document 1. The angle of emergence of reflected light intensified by interference in the multilayer film layer depends on the angle of incident light, so in a structure in which multilayer film layers are stacked on a flat surface, the perceived color changes significantly depending on the observation angle. In contrast, in the structure of Patent Document 1, the reflected light intensified by interference is scattered by the unevenness, so the color changes more gradually depending on the observation angle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-56942 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the more vivid the color observed from a structure, the more visible the attachment location of the structure will be when the structure is attached to an article. To improve the vividness of a specific color observed, it is desirable that the intensity of reflected light be high in the wavelength range of this specific color. In structures in which scattered reflected light is observed, such as the structure described in Patent Document 1, there is still room for improvement in a structure for increasing the intensity of reflected light over a wide observation angle. [Means for solving the problem]

[0006] A color-developing structure that solves the above problem comprises a concave-convex structure layer having a concave-convex structure on its surface composed of a plurality of concave-convex elements that are convex or concave portions, and an optical layer that is a laminated film positioned on the concave-convex structure, has a surface shape that follows the concave-convex structure, and emits reflected light that is intensified by interference, wherein, in a planar view of the concave-convex structure from a direction along the thickness direction of the concave-convex structure layer, the width of the concave-convex elements is 10 μm or more and 100 μm or less, the plurality of concave-convex elements include a first concave-convex element and a second concave-convex element, the maximum height Rz2 on the surface of the second concave-convex element is greater than the maximum height Rz1 on the surface of the first concave-convex element, and at least one of the plurality of concave-convex elements adjacent to the first concave-convex element is the second concave-convex element.

[0007] According to the above configuration, reflected light in a specific wavelength range, which is intensified by interference in the optical layer, is scattered by the uneven structure consisting of multiple uneven elements and emitted in various directions. Furthermore, at least the surface of the second uneven element has minute unevenness, which further scatters the reflected light and increases the intensity of the reflected light at each observation angle. Therefore, the specific color corresponding to the wavelength range of the reflected light intensified by the optical layer can be observed over a wide observation angle, and the observed specific color becomes more vivid. Furthermore, since the first uneven element and the second uneven element are adjacent to each other, uneven brightness within the surface of the color-producing structure is also reduced.

[0008] In the above configuration, the difference between the maximum height Rz2 and the maximum height Rz1 may be 0.01 μm or more and 5.0 μm or less. According to the above configuration, the difference in shape and scattering function between the first and second concave-convex elements is clear, which makes it possible to suitably adjust the period of the periodic structure and the scattering intensity. In addition, the height of the concave-convex elements on the surface of the second concave-convex elements is prevented from becoming excessively large, which makes it easier to form the second concave-convex elements.

[0009] In the above configuration, the plurality of concave and convex elements may be arranged in a two-dimensional lattice pattern in the plan view. According to the above configuration, it is easy to design the arrangement of the plurality of concave-convex elements and to form the plurality of concave-convex elements, and it is also easy to design the arrangement of the first concave-convex elements and the second concave-convex elements.

[0010] In the above configuration, the arrangement of the concave-convex elements in the two-dimensional grid may include a row made up of a plurality of the first concave-convex elements and a row made up of a plurality of the second concave-convex elements. According to the above configuration, it is possible to generate anisotropy in the region where scattering is increased within the surface of the color-producing structure. In addition, since the first uneven element or the second uneven element can be continuously formed for each row, it is possible to improve the efficiency of forming multiple uneven elements.

[0011] In the above configuration, in the two-dimensional lattice-like arrangement of the concave-convex elements, the row consisting of the plurality of first concave-convex elements and the row consisting of the plurality of second concave-convex elements may be arranged in a predetermined order. According to the above configuration, it is possible to more suitably generate anisotropy in the region where scattering is increased within the surface of the color-producing structure.

[0012] In the above configuration, the arrangement of the concave-convex elements in the two-dimensional grid may include a row in which the first concave-convex elements and the second concave-convex elements are arranged in a predetermined order. According to the above configuration, it is possible to arrange regions where scattering is increased isotropically within the surface of the color-producing structure.

[0013] In the above configuration, in the two-dimensional lattice-like arrangement of the uneven elements, the period of the arrangement of the uneven elements in a row consisting of a plurality of the uneven elements may be a reference period, and in adjacent rows, the positions of the uneven elements in the direction in which the rows extend may have a deviation of 1 / 2 of the reference period. According to the above configuration, even if the uneven elements are large, the grid pattern of the color-producing structure is prevented from being visible.

[0014] In the above configuration, the shape of the concave-convex elements in the plan view may be a square or a regular hexagon. According to the above configuration, the shape and arrangement of the uneven elements can be easily designed, and the scattering effect of the uneven structure can be suitably obtained.

[0015] In the above configuration, a ratio of a maximum value of a dimension in the thickness direction within the concave-convex element to a width of the concave-convex element may be 0.1 or more and 1.0 or less. According to the above-described configuration, reflection within the concave-convex elements is suppressed, and therefore light in a wavelength range different from the reflected light enhanced by the optical layer is prevented from emitting from the color-emitting structure, thereby improving the visibility of the color of the reflected light.

[0016] In the above configuration, a reference surface is a surface that is virtually set within the uneven element, which increases in height from the end of the uneven element toward the center when viewed in the plane and which forms a curve in a cross section along the thickness direction, the first uneven element may be a convex portion having the reference surface as its surface or a convex portion having minute concavities and convexities on the reference surface, and the second uneven element may be a convex portion having minute concavities and convexities on the reference surface.

[0017] According to the above configuration, the angle of the surface of the uneven element with respect to the incident light tends to be non-uniform within the surface, so that the scattering effect of the uneven structure can be suitably obtained.

[0018] In the above configuration, the proportion of flat portions included in the surface of the concave-convex structure layer may be 10% or less per unit area of the surface in the plan view.

[0019] According to the above configuration, the proportion of scattered light in the reflected light from the optical layer is sufficiently ensured, thereby accurately suppressing color changes due to changes in the observation angle. Furthermore, the proportion of specular reflection light in the reflected light from the optical layer is kept low, thereby reducing the strain on the eyes of the observer of the color-producing structure.

[0020] In the above configuration, the optical layer may be a stack of a plurality of dielectric thin films, and the refractive indexes of the dielectric thin films adjacent to each other in the optical layer may be different from each other. According to the above configuration, the intensity of the reflected light is greater than in a configuration that utilizes interference from a single thin film, and therefore the observed colors are more vivid.

[0021] In the above configuration, an absorbing layer may be provided on the optical layer on the opposite side to the concave-convex structure layer, and the absorbing layer may have light absorption properties that absorb at least a portion of light transmitted through the optical layer.

[0022] According to the above configuration, light in a wavelength range different from the reflected light enhanced by the optical layer is prevented from being visible when viewed from the side where the concave-convex structure layer is located, thereby preventing a decrease in the visibility of the color of the reflected light.

[0023] In the above configuration, an adhesive layer may be provided that is located on the opposite side of the optical layer from the concave-convex structure layer, and an outermost surface of the color-producing structure may be included in the adhesive layer. According to the above configuration, a color-developing structure suitable for a color-developing sticker or transfer sheet that is attached to an adherend so that the adherend is located on the opposite side of the optical layer from the concave-convex structure layer can be obtained.

[0024] In the above configuration, an antireflection layer may be provided on the side of the concave-convex structure layer opposite to the optical layer. According to the above configuration, the surface reflection of the color-producing structures is suppressed when viewed from the side where the concave-convex structure layer is located, and therefore, a decrease in the visibility of the color of reflected light is suppressed. [Effects of the Invention]

[0025] According to the present invention, the intensity of reflected light can be increased over a wide observation angle in a color-emitting structure. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 2 is a diagram showing a cross-sectional structure of a color-producing structure according to an embodiment. [Figure 2] FIG. 3 is a diagram showing a cross-sectional structure of a convex portion provided in a concave-convex structure layer according to an embodiment. [Figure 3] FIG. 2 is a diagram showing a perspective structure of a concave-convex structure layer in one embodiment. [Figure 4] 2A and 2B are diagrams showing a planar structure and a cross-sectional structure of a concave-convex structure layer according to an embodiment. [Figure 5] 10A and 10B are diagrams showing modified examples of the planar structure of the concavo-convex structure layer in one embodiment. [Figure 6] 10A and 10B are diagrams showing modified examples of the planar structure of the concavo-convex structure layer in one embodiment. [Figure 7] 10A and 10B are diagrams showing modified examples of the planar structure of the concavo-convex structure layer in one embodiment. [Figure 8] 10A and 10B are diagrams showing modified examples of the planar structure of the concavo-convex structure layer in one embodiment. [Figure 9] 10A and 10B are diagrams showing modified examples of the planar structure of the concavo-convex structure layer in one embodiment. [Figure 10] FIG. 10 is a diagram showing a part of the manufacturing process of the concavo-convex structure layer according to one embodiment, and is a diagram showing a step of forming a mold by cutting. [Figure 11] FIG. 4 is a diagram showing a part of a manufacturing process for a concave-convex structure layer according to one embodiment, illustrating a process for forming the concave-convex structure layer by extrusion molding. [Figure 12] 1 is a diagram showing a cross-sectional structure when a coloring structure according to an embodiment is applied to a coloring sticker. [Figure 13] FIG. 1 is a diagram showing a cross-sectional structure when a color-developing structure according to an embodiment is applied to a transfer sheet. [Figure 14] FIG. 4 is a diagram showing the relationship between the angle of incidence and the angle of reflection in the optical system used in the examples. [Figure 15] 10A and 10B are graphs showing measurement results of reflection characteristics of color-developing structures of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0027] An embodiment of a color-emitting structure will be described with reference to the drawings. The incident light and reflected light that the color-emitting structure targets are light in the visible region. In the following description, light in the visible region refers to light in the wavelength range of 360 nm to 830 nm.

[0028] [Basic structure of color-forming structure] As shown in FIG. 1, the color-forming structure 10 includes a substrate 20, a concave-convex structure layer 30, and a multilayer film layer 40.

[0029] The substrate 20 is a flat layer and supports the concave-convex structure layer 30. The substrate 20 is made of a material that transmits light in the visible region, i.e., a material that is transparent to light in the visible region. The substrate 20 is, for example, a synthetic quartz substrate or a sheet made of a resin such as polyethylene terephthalate, polycarbonate, acrylic, or polypropylene. From the viewpoint of increasing the flexibility of the color-developing structure 10, the substrate 20 is preferably a resin sheet. The thickness of the substrate 20 is, for example, 10 μm or more and 100 μm or less.

[0030] The concave-convex structure layer 30 is located on the substrate 20. The concave-convex structure layer 30 has a concave-convex structure on the surface opposite to the surface facing the substrate 20. The concave-convex structure is composed of a plurality of protrusions 31. The protrusions 31 protrude toward the multilayer film layer 40. The plurality of protrusions 31 include first protrusions 32 and second protrusions 33 that have different surface roughnesses. The protrusions 31 are an example of a concave-convex element, the first protrusions 32 are an example of a first concave-convex element, and the second protrusions 33 are an example of a second concave-convex element.

[0031] The concave-convex structure layer 30 is formed from a resin that transmits light in the visible range, i.e., a resin that is transparent to light in the visible range. Examples of the resin material for the concave-convex structure layer 30 include a photocurable resin, a thermosetting resin, and a thermoplastic resin. Specific examples of the resin material for the concave-convex structure layer 30 include acrylic, polycarbonate, polystyrene, AS resin, and MS resin.

[0032] The multilayer film layer 40 covers the surface of the concave-convex structure layer 30 and has a surface shape that follows the concave-convex structure of the concave-convex structure layer 30. The multilayer film layer 40 is an example of an optical layer. The multilayer film layer 40 is a stack of multiple thin films and has a structure in which high-refractive-index layers 41 and low-refractive-index layers 42 are alternately stacked. Each of the high-refractive-index layers 41 and the low-refractive-index layers 42 is a dielectric thin film. The refractive index of the high-refractive-index layer 41 is higher than the refractive index of the low-refractive-index layer 42. For example, the layer in contact with the concave-convex structure layer 30 is the high-refractive-index layer 41, and the outermost layer on the opposite side of the concave-convex structure layer 30 is the low-refractive-index layer 42.

[0033] The high-refractive index layer 41 and the low-refractive index layer 42 are formed from a material that transmits light in the visible region, i.e., a material that is transparent to light in the visible region. As long as the refractive index of the high-refractive index layer 41 is greater than that of the low-refractive index layer 42, the materials of these layers are not limited. However, the greater the difference in refractive index between the high-refractive index layer 41 and the low-refractive index layer 42, the more intense the reflected light can be obtained with fewer layers. From this perspective, for example, when the high-refractive index layer 41 and the low-refractive index layer 42 are made of inorganic materials, it is preferable that the high-refractive index layer 41 be made of titanium dioxide (TiO2) and the low-refractive index layer 42 be made of silicon dioxide (SiO2). However, the high-refractive index layer 41 and the low-refractive index layer 42 may also be made of organic materials.

[0034] The thickness of each of the high-refractive-index layers 41 and the low-refractive-index layers 42 may be designed using a transfer matrix method or the like depending on the desired color to be emitted by the color-emitting structure 10. The thickness of each of the high-refractive-index layers 41 and the low-refractive-index layers 42 may be selected, for example, from the range of 10 nm to 500 nm. The thicknesses of the layers constituting the multilayer film 40 may be the same or may vary depending on the layer. Note that FIG. 1 illustrates an example of the multilayer film 40 consisting of eight layers, in which high-refractive-index layers 41 and low-refractive-index layers 42 are alternately stacked in this order from the position closest to the concave-convex-structure layer 30. The number of layers and the stacking order of the multilayer film layer 40 are not limited thereto, and the high-refractive-index layers 41 and low-refractive-index layers 42 may be designed to obtain reflected light in the desired wavelength range. For example, the low-refractive-index layer 42 may be in contact with the concave-convex-structure layer 30, and the high-refractive-index layers 41 and low-refractive-index layers 42 may be alternately stacked thereon. The outermost layer on the opposite side to the concave-convex structure layer 30 may also be either the high refractive index layer 41 or the low refractive index layer 42. Furthermore, as long as the high refractive index layers 41 and the low refractive index layers 42 are alternately stacked, the material of the layer in contact with the concave-convex structure layer 30 and the outermost layer on the opposite side may be the same. Furthermore, the multilayer film layer 40 may include three or more layers with different refractive indices.

[0035] In short, the multilayer film 40 is configured so that the refractive indexes of adjacent layers are different from each other, and the reflectance of light incident on the multilayer film 40 in a specific wavelength range is higher than the reflectance in other wavelength ranges.

[0036] The coloring structure 10 does not necessarily have to include the base material 20. When the coloring structure 10 does not include the base material 20, the concave-convex structure layer 30 may be formed from a material other than resin, such as synthetic quartz.

[0037] [Configuration of uneven structure] The concave-convex structure of the concave-convex structure layer 30 will be described in detail. First, the characteristics relating to the surface roughness of the convex portions 31 will be described. Fig. 2 shows an enlarged example of the cross-sectional structure of the first convex portions 32 and the second convex portions 33.

[0038] Regarding the surface roughness of the first protrusions 32 and the second protrusions 33, the maximum height Rz2 on the surface of the second protrusions 33 is greater than the maximum height Rz1 on the surface of the first protrusions 32. The maximum heights Rz1 and Rz2 are measured in accordance with the method for measuring the maximum height Rz specified in JIS B 0601-2001. The maximum height Rz may be measured using, for example, a laser microscope.

[0039] 2, each of the first convex portions 32 and the second convex portions 33 has minute irregularities on its surface. The irregularities of the first convex portions 32 are first minute irregularities 34, and the irregularities of the second convex portions 33 are second minute irregularities 35. The height of the convex portions constituting the first minute irregularities 34 is smaller than that of the first convex portions 32, for example, equal to or less than the wavelength of light in the visible range. The height of the convex portions constituting the second minute irregularities 35 is smaller than that of the second convex portions 33, for example, equal to or less than the wavelength of light in the visible range. The height difference of the concaves and convexes of the second minute irregularities 35 is larger than the height difference of the concaves and convexes of the first minute irregularities 34.

[0040] In each of the minute asperities 34, 35, the arrangement of the convex portions and concave portions constituting the asperities may be regular or irregular. In each of the minute asperities 34, 35, the shape and height of the convex portions and concave portions constituting the asperities may be constant, may vary regularly, or may vary irregularly. In addition, the first convex portions 32 may not have the first minute asperities 34, and the surface of the first convex portions 32 may be smooth. In short, it is sufficient that the maximum height Rz2 of the second convex portions 33 is greater than the maximum height Rz1 of the first convex portions 32.

[0041] The first protrusion 32 and the second protrusion 33 are adjacent to each other. Specifically, at least one of the plurality of protrusions 31 adjacent to the first protrusion 32 is the second protrusion 33. Also, at least one of the plurality of protrusions 31 adjacent to the second protrusion 33 is the first protrusion 32.

[0042] When light is incident on the color-producing structure 10 of this embodiment, the light reflected at each interface between the high-refractive-index layer 41 and the low-refractive-index layer 42 in the multilayer film layer 40 interferes. Furthermore, due to the uneven structure formed by the convex portions 31 of the uneven structure layer 30, the angle of each interface relative to the incident light changes within the color-producing structure 10, causing the reflected light to be emitted in various directions. In other words, the reflected light from the multilayer film layer 40 is scattered. As a result, light in a specific wavelength range that has been intensified by interference is emitted in various directions, making a specific color visible at a wide observation angle.

[0043] The reflected light scattered by the convex portion 31 is further scattered by the minute asperities 34 and 35. For example, of the reflected light scattered by the first convex portion 32, the reflected light emitted toward the second convex portion 33 adjacent to the first convex portion 32 is scattered by the second minute asperities 35 and emitted in multiple directions. As a result, the intensity of the reflected light observed at each observation angle is increased. In other words, the intensity of the reflected light in a specific wavelength range that has been intensified by interference is increased. This enhances the vividness of a specific color observed at a wide observation angle. Furthermore, reflected light in the above-mentioned specific wavelength range can be observed whether the multilayer film layer 40 is observed from the side where the uneven structure layer 30 is located or from the opposite side of the uneven structure layer 30.

[0044] Since the multiple convex portions 31 include first convex portions 32 and second convex portions 33 with different maximum heights Rz, it is possible to control the period of the uneven structure, the degree of scattering of reflected light, the anisotropy of light and dark due to the scattering of reflected light, etc.

[0045] For example, since the plurality of convex portions 31 includes the first convex portions 32 and the second convex portions 33, the arrangement of the first convex portions 32 and the arrangement of the second convex portions 33 are each perceived as a periodic structure, and the arrangement of the convex portions 31 is prevented from being perceived as a single periodic structure. Therefore, even if the period of the convex portions 31 is within a range that easily causes light diffraction, the visibility of rainbow colors as diffracted light is prevented, and the visibility of the color of the reflected light enhanced by the multilayer film layer 40 is improved.

[0046] Furthermore, if the scattering effect of the uneven structure is too great, light in wavelength ranges other than the specific wavelength range enhanced by the multilayer film layer 40 will also be scattered, reducing the visibility of colors in the specific wavelength range. The multiple protrusions 31 include first protrusions 32 and second protrusions 33, which have different scattering strengths due to differences in surface roughness, and the scattering effect can be adjusted by adjusting the ratio and arrangement of the first protrusions 32 and second protrusions 33. Furthermore, by adjusting the arrangement of the first protrusions 32 and second protrusions 33, it is possible to create anisotropy in areas where reflected light scattering is increased, or conversely, to arrange areas where reflected light scattering is increased isotropically.

[0047] Optical effects such as diffraction and scattering can be adjusted by the characteristics of the convex portions 31 themselves, such as the size, shape, and arrangement of the convex portions 31, regardless of whether the first convex portions 32 and the second convex portions 33 are mixed. However, adjusting the optical effects by only the characteristics of the convex portions 31 places great restrictions on the design of the characteristics of the convex portions 31. In contrast, if the first convex portions 32 and the second convex portions 33 are mixed, the optical effects can also be adjusted by the arrangement of the first convex portions 32 and the second convex portions 33, which increases the degree of freedom in designing the characteristics of the convex portions 31.

[0048] Regarding the difference between the maximum height Rz1 of the first convex portion 32 and the maximum height Rz2 of the second convex portion 33, it is preferable that the maximum heights Rz1 and Rz2 satisfy the following (Formula 1). 0.01μm≦Rz2-Rz1≦5.0μm (1)

[0049] If the difference between the maximum height Rz2 and the maximum height Rz1 is 0.01 μm or more, the above-mentioned effect obtained by the plurality of convex portions 31 including the first convex portions 32 and the second convex portions 33 can be suitably obtained. Furthermore, if the difference between the maximum height Rz2 and the maximum height Rz1 is 5.0 μm or less, the height of the second minute unevenness 35 in the second convex portions 33 can be prevented from becoming excessively large. Because the convex portions 31 are small enough to scatter light but not be visible, it is difficult to form unevenness with an excessive height on the convex portions 31. If the height of the second minute unevenness 35 is suppressed, it is easy to form the second convex portions 33 having the second minute unevenness 35.

[0050] Next, the characteristics of the size of the protrusion 31 will be described. The width D of the protrusions 31 is 10 μm or more and 100 μm or less. It is preferable that the width D is constant among the multiple protrusions 31. If the width D is 10 μm or more, the diffraction of light due to the regular arrangement of the protrusions 31 is suppressed. Therefore, the visibility of rainbow colors as diffracted light is suppressed, and the visibility of the color of the reflected light intensified by the multilayer film layer 40 is improved. Furthermore, if the width D is 10 μm or more, the protrusions 31 do not become too fine, facilitating the formation of a concave-convex structure and improving the production efficiency of the color-producing structure 10. On the other hand, if the width D is 100 μm or less, the protrusions 31 are prevented from being recognized by the human eye as a single structure. From the viewpoint of achieving a balance between these effects, the width D is preferably 40 μm or more and 50 μm or less.

[0051] The maximum length H of the protrusions 31 is the maximum value of the height of the protrusions 31 along the thickness direction of the concave-convex structure layer 30. The maximum length H is preferably, for example, 10 μm or less. The maximum length H of the multiple protrusions 31 may or may not be constant. For example, the maximum length H of the first protrusions 32 and the maximum length H of the second protrusions 33 may be different from each other. The aspect ratio of the protrusions 31, i.e., the ratio of the maximum length H to the width D, is preferably 0.1 or more and 1.0 or less. If the aspect ratio is 0.1 or more, an uneven structure is formed that has sufficient undulations compared to a flat surface, and therefore the scattering effect of the uneven structure is high.

[0052] On the other hand, if the aspect ratio is 1.0 or less, reflection of light within the convex portions 31 is suppressed. If reflection within the convex portions 31 is large, it is possible that light of a wavelength range different from the wavelength range enhanced by the multilayer film layer 40, among the incident light, is reflected within the convex portions 31 and emitted toward the viewer. If such light is visible, the visibility of the color of the reflected light enhanced by the multilayer film layer 40 decreases. In contrast, as described above, if the aspect ratio is 1.0 or less, the visibility of light of a wavelength range different from the light reflected by the multilayer film layer 40 is suppressed, and therefore a decrease in the clarity of the perceived color is suppressed. Note that the convex portions 31 are preferably designed to have a shape that makes it difficult to reflect light of a wavelength range different from the wavelength range enhanced by the multilayer film layer 40.

[0053] When the virtual plane on which the base ends of the convex portions of the minute concaves and convexes 34 and 35 are located is defined as a reference plane 31S, the height of the reference plane 31S gradually increases from the end portions of the convex portions 31 toward the center in the direction in which the concave-convex structure layer 30 extends, i.e., in the direction perpendicular to the thickness direction. The height of the reference plane 31S is greatest at the center of the convex portions 31 in the direction in which the concave-convex structure layer 30 extends.

[0054] The reference surface 31S is a curved surface, and in a cross section along the thickness direction, the reference surface 31S forms a curved line that protrudes toward the multilayer film layer 40. When the reference surface 31S forms a curved line, the angle of the surface of the convex portion 31 with respect to the incident light tends to be more non-uniform within the surface, which tends to enhance the scattering effect of the reflected light. The curvature of this curve may or may not be constant. For example, the curvature of the curve formed by the reference surface 31S may be different between the end portion and the center portion of the convex portion 31.

[0055] If the curvature of the curve is constant, it is easier to suppress light reflection within the convex portions 31 compared to a configuration in which the curvature is greater at the center of the convex portions 31. On the other hand, if the curvature of the curve is not constant, the convex portions 31 can be configured so that the angle of the surface of the convex portions 31 with respect to the incident light becomes more non-uniform within the surface, and therefore the shape of the convex portions 31 can also be designed to enhance the scattering effect of the reflected light of the multilayer film layer 40.

[0056] In other words, the reference plane 31S is an imaginary plane set within the protrusion 31, the height of which increases from the end portion toward the center of the protrusion 31, and the plane that forms a curve in a cross section along the thickness direction. The first protrusion 32 is a protrusion that has the reference plane 31S as its outermost surface, or a protrusion that has first minute irregularities 34 on the reference plane 31S, and the second protrusion 33 is a protrusion that has second minute irregularities 35 on the reference plane 31S.

[0057] [Arrangement of convex parts] The following describes the characteristics of the arrangement of the convex portions 31. Fig. 3 shows a perspective structure of the concave-convex-structure layer 30, and Fig. 4 shows the planar structure and cross-sectional structure of the concave-convex-structure layer 30. In the following figures, in order to distinguish between the first convex portions 32 and the second convex portions 33, dots are added to the surface of the second convex portions 33.

[0058] As shown in FIG. 3, in the concave-convex structure of the concave-convex structure layer 30, a plurality of convex portions 31 are arranged without any gaps. 4, in a plan view of the concave-convex structure seen from the thickness direction of the concave-convex structure layer 30, the convex portions 31 have a square shape. The multiple convex portions 31 have the same square shape, and are arranged in a square lattice pattern along the direction in which the sides of the square extend. A square lattice is an example of a two-dimensional lattice.

[0059] More specifically, the plurality of protrusions 31 are aligned along a first direction dx and a second direction dy. The first direction dx and the second direction dy are perpendicular to each other. The plurality of protrusions 31 are aligned such that the first direction dx and the second direction dy are aligned along the directions in which the sides of the squares that form the protrusions 31 in the plan view extend.

[0060] When a row of protrusions 31 extending in the first direction dx is defined as one row, and the rows of protrusions 31 aligned along the second direction dy are referred to in order as the first row, second row, third row, ..., the positions of the protrusions 31 in the first direction dx in the 2n-1th row (n is an integer greater than or equal to 1) match the positions of the protrusions 31 in the first direction dx in the 2nth row. Furthermore, the positions of the protrusions 31 in the 2nth row in the first direction dx match the positions of the protrusions 31 in the 2n+1th row in the first direction dx. In other words, the positions of the centers C of the protrusions 31 in the first direction dx match in adjacent rows.

[0061] The width D of the protrusions 31 is the length of one side of the square. The period Px of the arrangement of the protrusions 31 in the first direction dx and the period Py of the arrangement of the protrusions 31 in the second direction dy match, and the periods Px and Py match the width D. In this configuration, as described above, the multiple protrusions 31 are arranged without any gaps, and the surface of the concave-convex structure layer 30 does not have any flat portions.

[0062] All of the protrusions 31 included in the 2n-1th row are first protrusions 32, and all of the protrusions 31 included in the 2nth row are second protrusions 33. That is, rows made up of the first protrusions 32 and rows made up of the second protrusions 33 are arranged alternately along the second direction dy.

[0063] In an arrangement of only the first protrusions 32, the period P1x of the arrangement of the first protrusions 32 in the first direction dx matches the period Px of the protrusions 31, and the period P1y of the arrangement of the first protrusions 32 in the second direction dy is twice the period Py of the protrusions 31. Similarly, in an arrangement of only the second protrusions 33, the period P2x of the arrangement of the second protrusions 33 in the first direction dx matches the period Px of the protrusions 31, and the period P2y of the arrangement of the second protrusions 33 in the second direction dy is twice the period Py of the protrusions 31.

[0064] In the above configuration, of the eight protrusions 31 adjacent to one first protrusion 32 in any direction, in other words, of the eight protrusions 31 surrounding one first protrusion 32, six protrusions 31 are second protrusions 33. Similarly, of the eight protrusions 31 adjacent to one second protrusion 33 in any direction, six protrusions 31 are first protrusions 32.

[0065] As described above, the alternating arrangement of rows of first convex portions 32 and rows of second convex portions 33 generates anisotropy in regions where the scattering of reflected light is increased within the surface of the coloring structure 10. Therefore, by adjusting the size of the convex portions 31, it is possible to make the anisotropy of light and dark visible within the surface of the coloring structure 10. Therefore, it is possible to obtain a coloring structure 10 suitable for applications where such anisotropy of light and dark is desired.

[0066] Next, a description will be given of modified examples of the arrangement of the convex portions 31. Fig. 5 shows the planar structure of the concave-convex structure layer 30 in a first modified example. 5, in the first modified example, similarly to the embodiment shown in Fig. 4, the shape of the protrusions 31 in the plan view is square, and the plurality of protrusions 31 are arranged in a square lattice pattern. That is, the plurality of protrusions 31 are arranged along the first direction dx and the second direction dy, and the positions of the centers C of the protrusions 31 in the first direction dx coincide in adjacent rows along the second direction dy.

[0067] On the other hand, in the first modified example, the arrangement of the first protrusions 32 and the second protrusions 33 is different from that of the embodiment shown in Fig. 4. In detail, the first protrusions 32 and the second protrusions 33 are alternately arranged along the first direction dx, and the first protrusions 32 and the second protrusions 33 are alternately arranged along the second direction dy. That is, in both the 2n-1th row and the 2nth row, the rows of protrusions 31 include a mixture of the first protrusions 32 and the second protrusions 33.

[0068] In an arrangement of only the first protrusions 32, the period P1x of the arrangement of the first protrusions 32 in the first direction dx is twice the period Px of the protrusions 31, and the period P1y of the arrangement of the first protrusions 32 in the second direction dy is twice the period Py of the protrusions 31. Similarly, in an arrangement of only the second protrusions 33, the period P2x of the arrangement of the second protrusions 33 in the first direction dx is twice the period Px of the protrusions 31, and the period P2y of the arrangement of the second protrusions 33 in the second direction dy is twice the period Py of the protrusions 31.

[0069] In the above configuration, of the eight protrusions 31 adjacent to one first protrusion 32 in any direction, four protrusions 31 are second protrusions 33. Similarly, of the eight protrusions 31 adjacent to one second protrusion 33 in any direction, four protrusions 31 are first protrusions 32.

[0070] In the first modification, the first convex portions 32 and the second convex portions 33 are alternately arranged in each of the first direction dx and the second direction dy, so that the region in the surface of the coloring structure 10 where the scattering of reflected light is increased becomes isotropic. As a result, the anisotropy of light and dark in the surface of the coloring structure 10 is less visible. Therefore, the coloring structure 10 is obtained, which is suitable for applications where small anisotropy of light and dark is desired.

[0071] 6 shows the planar structure of the concave-convex structure layer 30 in the second modified example. In the second modified example, the shape of the convex portions 31 in the plan view is square, and the convex portions 31 are arranged in an oblique lattice pattern. The oblique lattice is a two-dimensional lattice in which a unit cell is a parallelogram with two adjacent sides of different lengths.

[0072] Specifically, rows each consisting of a plurality of protrusions 31 aligned in the first direction dx are aligned in the second direction dy. The positions of the protrusions 31 in the 2n-1th row in the first direction dx are shifted by 1 / 2 the period Px of the protrusions 31 from the positions of the protrusions 31 in the 2nth row in the first direction dx. Similarly, the positions of the protrusions 31 in the 2nth row in the first direction dx are shifted by 1 / 2 the period Px from the positions of the protrusions 31 in the 2n+1th row in the first direction dx. In other words, the positions of the centers C of the protrusions 31 in the first direction dx in adjacent rows are shifted by 1 / 2Px.

[0073] The protrusions 31 included in the 2n-1th row are all first protrusions 32, and the protrusions 31 included in the 2nth row are all second protrusions 33. That is, rows made up of the first protrusions 32 and rows made up of the second protrusions 33 are arranged alternately along the second direction dy.

[0074] In an arrangement of only the first protrusions 32, the period P1x of the arrangement of the first protrusions 32 in the first direction dx matches the width D, which is the period Px of the protrusions 31, and the period P1y of the arrangement of the first protrusions 32 in the second direction dy is twice the width D. Similarly, in an arrangement of only the second protrusions 33, the period P2x of the arrangement of the second protrusions 33 in the first direction dx matches the period Px of the protrusions 31, and the period P2y of the arrangement of the second protrusions 33 in the second direction dy is twice the width D of the protrusions 31.

[0075] In the above configuration, of the six protrusions 31 adjacent to one first protrusion 32 in any direction, four protrusions 31 are second protrusions 33. Similarly, of the six protrusions 31 adjacent to one second protrusion 33 in any direction, four protrusions 31 are first protrusions 32.

[0076] In the second modification, the rows of the first convex portions 32 and the rows of the second convex portions 33 are alternately arranged, thereby generating anisotropy in the region where the scattering of reflected light is increased. Therefore, it is possible to obtain a color-producing structure 10 suitable for applications where anisotropy of light and dark is desired.

[0077] Furthermore, compared to the form shown in Figure 4 above and the first modified example in which the protrusions 31 are arranged in a square lattice pattern along the first direction dx and the second direction dy, even when the protrusions 31 are large, the visibility of a lattice pattern on the color-producing structure 10 is reduced.

[0078] 7 shows the planar structure of the concave-convex structure layer 30 in the third modified example. In the third modified example, as in the second modified example, the shape of the convex portions 31 in the plan view is square, and the multiple convex portions 31 are arranged in an oblique lattice pattern. That is, rows of multiple convex portions 31 arranged in the first direction dx are arranged in the second direction dy, and in adjacent rows along the second direction dy, the positions of the centers C of the convex portions 31 in the first direction dx are shifted by ½Px.

[0079] On the other hand, the third modified example differs from the second modified example in the arrangement of the first protrusions 32 and the second protrusions 33. Specifically, in each row, the first protrusions 32 and the second protrusions 33 are alternately arranged along the first direction dx. That is, in both the 2n-1th row and the 2nth row, the rows of protrusions 31 include a mixture of the first protrusions 32 and the second protrusions 33.

[0080] In adjacent rows, the positions of the convex portions 31 are shifted by 1 / 2 of the period Px, so that along the second direction there are areas where parts of the first convex portions 32 are continuous, areas where parts of the first convex portions 32 and parts of the second convex portions 33 are arranged alternately, and areas where parts of the second convex portions 33 are continuous.

[0081] In an arrangement of only the first protrusions 32, the period P1x of the arrangement of the first protrusions 32 in the first direction dx is twice the width D, which is the period Px of the protrusions 31, and the period P1y of the arrangement of the first protrusions 32 in the second direction dy, which have the same position in the first direction dx, is twice the width D. Similarly, in an arrangement of only the second protrusions 33, the period P2x of the arrangement of the second protrusions 33 in the first direction dx is twice the period Px of the protrusions 31, and the period P2y of the arrangement of the second protrusions 33 in the second direction dy, which have the same position in the first direction dx, is twice the width D of the protrusions 31.

[0082] In the above configuration, of the six protrusions 31 adjacent to one first protrusion 32 in any direction, four protrusions 31 are second protrusions 33. Similarly, of the six protrusions 31 adjacent to one second protrusion 33 in any direction, four protrusions 31 are first protrusions 32.

[0083] In the third modification, similar to the second modification, the visibility of the grid pattern on the coloring structure 10 is reduced, and the region where the scattering of reflected light is greater isotropic than in the second modification. Therefore, the coloring structure 10 is suitable for applications where small anisotropy of light and dark is desired.

[0084] 8 shows the planar structure of the concave-convex structure layer 30 in the fourth modified example. In the fourth modified example, the shape of the convex portions 31 in the plan view is a regular hexagon, and the convex portions 31 are arranged in a triangular lattice pattern. In other words, the convex portions 31 are arranged in a hexagonal lattice pattern. The triangular lattice and the hexagonal lattice are examples of two-dimensional lattices.

[0085] More specifically, the plurality of protrusions 31 are arranged along the first direction dx such that the sides of the regular hexagons of adjacent protrusions 31 are in contact with each other. The plurality of protrusions 31 are arranged such that the direction in which a pair of opposing sides of the regular hexagon extends is along the second direction dy. The rows of protrusions 31 extending in the first direction dx are arranged along the second direction dy.

[0086] As in the fourth modification, when the width in the short-side direction of the protrusion 31 differs from the width in the long-side direction, both the width D1 in the short-side direction and the width D2 in the long-side direction are set to 10 μm or more and 100 μm or less. The width D1 in the short-side direction is the length of the short side of a virtual smallest rectangle in which the protrusion 31 is inscribed in the plan view. The width D2 in the long-side direction is the length of the long side of the smallest rectangle. The maximum length H of the protrusion 31 may be set based on the width D1 in the short-side direction; that is, it is preferable that the ratio of the maximum length H to the width D1 in the short-side direction is 0.1 or more and 1.0 or less. The form in which the protrusion 31 has a square shape in the plan view is a form in which the width D1 in the short-side direction and the width D2 in the long-side direction are the same.

[0087] In rows of adjacent protrusions 31 along the second direction dy, the positions of the centers C of the protrusions 31 in the first direction dx are shifted by half the width D1, which is the period Px of the protrusions 31. Rows of adjacent protrusions 31 along the second direction dy are in contact with each other, and in this configuration, the surface of the concave-convex structure layer 30 does not have a flat portion.

[0088] The protrusions 31 included in the 2n-1th row are all first protrusions 32, and the protrusions 31 included in the 2nth row are all second protrusions 33. That is, rows made up of the first protrusions 32 and rows made up of the second protrusions 33 are arranged alternately along the second direction dy.

[0089] In an arrangement of only the first protrusions 32, the period P1x of the arrangement of the first protrusions 32 in the first direction dx matches the width D1, which is the period Px of the protrusions 31, and the period P1y of the arrangement of the first protrusions 32 in the second direction dy is 1.5 times the width D2 of the protrusions 31. Similarly, in an arrangement of only the second protrusions 33, the period P2x of the arrangement of the second protrusions 33 in the first direction dx matches the period Px of the protrusions 31, and the period P2y of the arrangement of the second protrusions 33 in the second direction dy is 1.5 times the width D2 of the protrusions 31.

[0090] In the above configuration, of the six protrusions 31 adjacent to one first protrusion 32 in any direction, four protrusions 31 are second protrusions 33. Similarly, of the six protrusions 31 adjacent to one second protrusion 33 in any direction, four protrusions 31 are first protrusions 32.

[0091] In the fourth modification, the rows of the first convex portions 32 and the rows of the second convex portions 33 are alternately arranged, thereby generating anisotropy in the region where the scattering of reflected light is increased. Therefore, it is possible to obtain a color-producing structure 10 suitable for applications where anisotropy of light and dark is desired.

[0092] Furthermore, compared to a configuration in which the square protrusions 31 are arranged in a square lattice pattern in a plan view, even when the protrusions 31 are large, a lattice pattern is less likely to be visible on the color-producing structure 10. Furthermore, because the shape of the protrusions 31 in the plan view is a regular hexagon, the direction in which the scattered reflected light is emitted is more likely to be wider than when the shape of the protrusions 31 is square.

[0093] 9 shows the planar structure of the concave-convex structure layer 30 in the fifth modified example. In the fifth modified example, as in the fourth modified example, the shape of the convex portions 31 in the plan view is a regular hexagon, and the multiple convex portions 31 are arranged in a triangular lattice pattern. That is, rows of multiple convex portions 31 arranged in the first direction dx are arranged in the second direction dy, and in adjacent rows along the second direction dy, the positions of the centers C of the convex portions 31 in the first direction dx are shifted by ½Px.

[0094] On the other hand, the fifth modified example differs from the fourth modified example in the arrangement of the first protrusions 32 and the second protrusions 33. Specifically, in each row, the first protrusions 32 and the second protrusions 33 are alternately arranged along the first direction dx. That is, in both the 2n-1th row and the 2nth row, the rows of protrusions 31 include a mixture of the first protrusions 32 and the second protrusions 33.

[0095] In adjacent rows, the positions of the convex portions 31 are shifted by 1 / 2 of the period Px, so that along the second direction there are areas where parts of the first convex portions 32 are continuous, areas where parts of the first convex portions 32 and parts of the second convex portions 33 are arranged alternately, and areas where parts of the second convex portions 33 are continuous.

[0096] In an arrangement of only the first protrusions 32, the period P1x of the arrangement of the first protrusions 32 in the first direction dx is twice the width D1, which is the period Px of the protrusions 31, and the period P1y of the arrangement of the first protrusions 32 in the second direction dy, which have the same position in the first direction dx, is 1.5 times the width D2 of the protrusions 31. Similarly, in an arrangement of only the second protrusions 33, the period P2x of the arrangement of the second protrusions 33 in the first direction dx is twice the period Px of the protrusions 31, and the period P2y of the arrangement of the second protrusions 33 in the second direction dy, which have the same position in the first direction dx, is 1.5 times the width D2 of the protrusions 31.

[0097] In the above configuration, of the six protrusions 31 adjacent to one first protrusion 32 in any direction, four protrusions 31 are second protrusions 33. Similarly, of the six protrusions 31 adjacent to one second protrusion 33 in any direction, four protrusions 31 are first protrusions 32.

[0098] In the fifth modification, similar to the fourth modification, the visibility of the grid pattern on the color-producing structure 10 is reduced, and the direction of the scattered reflected light tends to be wider. Furthermore, in the fifth modification, the region where the scattered reflected light is more highly scattered is more isotropic than in the fourth modification. Therefore, a color-producing structure 10 suitable for applications where small anisotropy of light and dark is desired is obtained.

[0099] The shape of the protrusions 31 in the plan view is not limited to a square or a regular hexagon, but may be another polygon such as a triangle or a rectangle, or may be a circle. Furthermore, the shape of the protrusions 31 in the plan view does not have to be uniform among the multiple protrusions 31.

[0100] To enhance the scattering effect of reflected light and emit the reflected light over a wider angle, it is preferable that the angle of the surface of the protrusions 31 relative to the incident light be as non-uniform as possible within the surface. For example, if the shape of the protrusions 31 in the plan view is quadrangular, the change in the inclination of the reference plane 31S from the vertex of the rectangle toward the center of the rectangle is different from the change in the inclination of the reference plane 31S from the midpoint of the side of the rectangle toward the center of the rectangle. Therefore, the inclination tends to vary greatly depending on the location within the surface of the protrusions 31. Therefore, when the shape of the protrusions 31 is quadrangular, the scattering effect of reflected light is likely to be enhanced.

[0101] Furthermore, the height of the reference surface 31S of the convex portion 31 does not have to gradually increase from the end portion of the convex portion 31 toward the center portion when viewed in the plane, and the reference surface 31S does not have to be curved in a cross section along the thickness direction.

[0102] The multiple protrusions 31 may be arranged in a two-dimensional lattice pattern different from the above-described form, or may be arranged regularly or irregularly in an arrangement different from the two-dimensional lattice. When the arrangement of the protrusions 31 includes a row consisting only of the first protrusions 32 and a row consisting only of the second protrusions 33, these rows may be arranged in a predetermined order rather than alternately, and the arrangement period of these rows may not be constant. When the row of the protrusions 31 includes both the first protrusions 32 and the second protrusions 33, the first protrusions 32 and the second protrusions 33 may be arranged in a predetermined order rather than alternately, and the arrangement period of the first protrusions 32 and the second protrusions 33 may not be constant. Furthermore, in the arrangement of the multiple protrusions 31, the first protrusions 32 and the second protrusions 33 may be arranged irregularly. Essentially, it is sufficient that at least one of the multiple protrusions 31 surrounding a first protrusion 32 is a second protrusion 33.

[0103] The more irregular the shape and arrangement of the plurality of protrusions 31, the more effective the scattering of reflected light. For example, when the protrusions 31 have a quadrangular shape in the plan view, and at least one of the widths in the short side direction and the widths in the long side direction of adjacent protrusions 31 is different from each other, the more effective the scattering of reflected light is compared to a case where the shape of the plurality of protrusions 31 is uniform.

[0104] Furthermore, the multiple convex portions 31 may be arranged with gaps between adjacent convex portions 31. In other words, the surface of the concave-convex structure layer 30 may have flat portions between adjacent convex portions 31. However, in the above-mentioned plan view, the ratio of flat portions per unit area on the surface of the concave-convex structure layer 30 is preferably 10% or less. Reflected light is scattered less in the area where the multilayer film layer 40 is laminated on the flat portions. However, if the ratio of flat portions is 10% or less, the ratio of scattered components in the reflected light from the multilayer film layer 40 is sufficiently ensured, thereby effectively suppressing color changes due to changes in observation angle. Furthermore, if the ratio of flat portions is 10% or less, the ratio of specular reflection components in the reflected light from the multilayer film layer 40 is kept low, thereby reducing the strain on the observer's eyes. Note that, to enhance these effects, the smaller the ratio of flat portions, the more preferable.

[0105] [Method of manufacturing color-developing structure] A method for manufacturing the color-developing structure 10 will be described. Methods for forming the concave-convex structure of the concave-convex structure layer 30 include transfer molding using heat or light, injection molding, extrusion molding, mechanical processing such as cutting, etching, etc. The intaglio plate used for transfer molding, etc., is formed by mechanical processing or etching.

[0106] For example, when machining is used, a concave-convex structure consisting of protrusions 31 having minute asperities 34, 35, or an intaglio plate for forming the concave-convex structure, can be formed by adjusting the cutting conditions and selecting an appropriate tool. The concave-convex structure or intaglio plate may also be formed by processing the same area multiple times or by combining different processing methods. The difference in surface roughness between the first protrusions 32 and the second protrusions 33 can be achieved by changing the processing conditions, changing the tool, or controlling tool wear.

[0107] An example of a method for manufacturing the relief structure layer 30 using machining and extrusion molding will be described with reference to FIGS. First, as shown in Fig. 10, a roll-shaped mold 100, which is an intaglio plate for forming the concave-convex structure, is formed by cutting. Specifically, while the mold 100 attached to a processing machine is rotated, a cutting tool 110 corresponding to the shape of the desired convex portions 31 is pressed against the mold 100. By reciprocating the cutting tool 110, concave portions 101 corresponding to the convex portions 31 are formed one by one in the surface of the mold 100.

[0108] For example, by using a cutting tool 110 with a smooth curved surface, a recess corresponding to the first protrusion 32 is formed, and by using a cutting tool 110 with a rough curved surface, a recess corresponding to the second protrusion 33 is formed. If each row of protrusions 31 is configured with only either the first protrusion 32 or the second protrusion 33, the load required for changing the cutting tool and aligning the processing location can be reduced.

[0109] 11, the fabricated mold 100 and a molding roll 220 are mounted in an extrusion molding machine 200, and molten resin is extruded from a T-die 210 between the mold 100 and the roll 220. The resin that has passed between the mold 100 and the roll 220 is cooled, thereby obtaining a resin sheet 60 having a surface onto which the concave-convex patterns of the mold 100 are transferred. The obtained resin sheet 60 is a sheet comprising a concave-convex structure layer 30.

[0110] Next, an example of a method for manufacturing a concave-convex structure layer 30 by transfer molding using light will be described. In this case, a photocurable resin is applied to the substrate 20, and the resin is cured by irradiating it with light such as ultraviolet light while pressing an intaglio plate having inverted concave-convex patterns of the pattern to be formed against the resin. As a result, a resin-made concave-convex structure layer 30 having a surface onto which the intaglio plate concave-convex patterns are transferred is formed on the substrate 20. Note that a thermosetting resin may be used instead of the photocurable resin, and in this case, heating may be performed instead of irradiating light.

[0111] After the concave-convex structure layer 30 is formed, the layers that make up the multilayer film layer 40 are laminated in order on the concave-convex structured surface of the concave-convex structure layer 30. When the high-refractive index layer 41 and the low-refractive index layer 42 that make up the multilayer film layer 40 are made of inorganic materials, the high-refractive index layer 41 and the low-refractive index layer 42 are each formed using a known thin film formation technique such as sputtering, vacuum evaporation, or atomic layer deposition. When the high-refractive index layer 41 and the low-refractive index layer 42 are each formed of organic materials, the high-refractive index layer 41 and the low-refractive index layer 42 may be formed using a known technique such as self-organization.

[0112] [Examples of application of color-forming structures] As application examples of the color-forming structure, the configurations of a color-forming sticker and a transfer sheet will be described. First, the structure when the color-forming structure is applied to a color-forming sticker will be described. The color-forming sticker is attached to an adherend and used for decorating the adherend, etc.

[0113] 12, the coloring structure constituting the coloring sticker 11 includes a substrate 20, a concave-convex structure layer 30, a multilayer film layer 40, an absorption layer 50, and an adhesive layer 51. The absorption layer 50 and the adhesive layer 51 are located on the opposite side of the multilayer film layer 40 from the concave-convex structure layer 30.

[0114] The absorbing layer 50 covers the irregularities on the outermost surface of the multilayer film layer 40. The absorbing layer 50 has light-absorbing properties that absorb light transmitted through the multilayer film layer 40. For example, the absorbing layer 50 contains a material that absorbs light in the visible region, such as a light absorber or a black pigment. Specifically, the absorbing layer 50 is preferably a layer in which a black inorganic pigment, such as carbon black, titanium black, black iron oxide, or black complex oxide, is mixed with a resin. The thickness of the absorbing layer 50 is, for example, 1 μm or more and 10 μm or less.

[0115] The adhesive layer 51 contacts the absorbent layer 50 on the side opposite the multilayer film layer 40 with respect to the absorbent layer 50. The surface of the adhesive layer opposite to the surface contacting the absorbent layer 50 is the outermost surface of the color-developing sticker 11. The adhesive layer 51 is a layer that has adhesive properties to an adherend, and is made of, for example, an acrylic or urethane pressure-sensitive adhesive. The thickness of the adhesive layer 51 is, for example, 10 μm or more and 100 μm or less.

[0116] The absorbing layer 50 and the adhesive layer 51 are formed by 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, or a gravure coating method.

[0117] The color-forming sticker 11 is attached to the adherend so that the adhesive layer 51 is in contact with the adherend, i.e., so that the adherend is located on the opposite side of the multilayer film layer 40 from the uneven structure layer 30. An observer observes the color-forming sticker 11 from the side of the multilayer film layer 40 where the uneven structure layer 30 is located. An article consisting of the adherend and the color-forming sticker 11 is a color-forming article.

[0118] Of the incident light, a portion of the light outside the specific wavelength range reflected by the multilayer film layer 40 is transmitted through the multilayer film layer 40. Because the wavelength range of this transmitted light is different from the wavelength range of the light reflected by the multilayer film layer 40, when such transmitted light is visible, the visibility of the color of the reflected light decreases. In the color-developing sticker 11, the absorption layer 50 is provided, so that the transmitted light through the multilayer film layer 40 is absorbed by the absorption layer 50, and this transmitted light is prevented from being reflected by the surface of the adherend or the like and being emitted toward the substrate 20.

[0119] Therefore, light in a wavelength range different from the reflected light from the multilayer film layer 40 is prevented from being seen by the observer, and therefore the visibility of the color of the reflected light is prevented from decreasing. As a result, the desired color can be suitably obtained in the color-developing sticker 11.

[0120] The color-forming sticker 11 may have an anti-reflection layer on the surface of the base material 20 opposite to the concave-convex structure layer 30. The anti-reflection layer has the function of suppressing surface reflection on the outermost surface of the color-forming sticker 11. The suppression of surface reflection by the anti-reflection layer further improves the visibility of the color of the reflected light intensified by the multilayer film layer 40.

[0121] Next, a structure in which the color-developing structure is applied to a transfer sheet will be described. The transfer sheet is a sheet used to attach a color-developing sheet to an adherend. In other words, the transfer sheet is used to transfer the color-developing sheet provided on the transfer sheet to an adherend.

[0122] As shown in FIG. 13, the color-developing structure constituting the transfer sheet 12 includes a substrate 20, a concave-convex structure layer 30, a multilayer film layer 40, an absorption layer 52, and an adhesive layer 53. The transfer sheet 12 is configured so that the substrate 20 can be peeled off from the concave-convex structure layer 30. Specifically, the transfer sheet 12 includes a release layer 54 between the substrate 20 and the concave-convex structure layer 30. The release layer 54 contains a component that functions as a release agent, such as silicone oil or a fluorine compound. The release layer 54 is formed on the surface of the substrate 20 by a known coating method.

[0123] The absorbing layer 52 and the adhesive layer 53 are located on the opposite side of the multilayer film layer 40 from the concave-convex structure layer 30. The absorbing layer 52 covers the concave-convex portions on the outermost surface of the multilayer film layer 40. The adhesive layer 53 is in contact with the absorbing layer 52 on the opposite side of the multilayer film layer 40 from the absorbing layer 52, and is located on the outermost side of the transfer sheet 12. The absorbing layer 52 has a structure similar to that of the absorbing layer 50 of the color-forming sticker 11 described above, and the adhesive layer 53 has a structure similar to that of the adhesive layer 51 of the color-forming sticker 11 described above.

[0124] When the transfer sheet 12 is used, it is fixed to the surface of the adherend so that the adhesive layer 53 contacts the adherend. Then, the substrate 20 is peeled off. The substrate 20 may be peeled off by peeling at the interface between the substrate 20 and the release layer 54, or by peeling at the interface between the release layer 54 and the concave-convex-structure layer 30, resulting in peeling together with the release layer 54. This transfers the color-forming sheet 13, which includes the concave-convex-structure layer 30, the multilayer film layer 40, the absorption layer 52, and the adhesive layer 53, to the adherend. When peeling occurs at the interface between the substrate 20 and the release layer 54, the release layer 54 is also included in the color-forming sheet 13. The outermost surface of the color-forming sheet 13 opposite the adhesive layer 53 is the surface of the release layer 54 or the concave-convex-structure layer 30.

[0125] As described above, the transfer sheet 12 and the color-forming sheet 13 are attached to the adherend so that the adherend is located on the opposite side of the multilayer film layer 40 from the uneven structure layer 30. An observer observes the color-forming sheet 13 from the side of the multilayer film layer 40 where the uneven structure layer 30 is located. An article consisting of the adherend and the color-forming sheet 13 is a color-forming article.

[0126] Since the color-forming sheet 13 includes the absorbing layer 52, the transmitted light through the multilayer film layer 40 is absorbed by the absorbing layer 52, and this transmitted light is prevented from being reflected by the surface of the adherend or the like and being emitted toward the concave-convex structure layer 30. This prevents light in a wavelength range different from the light reflected from the multilayer film layer 40 from being seen by an observer, thereby preventing a decrease in the visibility of the color of the reflected light. This allows the color-forming sheet 13 to preferably produce the desired color.

[0127] Furthermore, since the color-forming sheet 13 does not have the base material 20 that is the base material used during manufacturing, the flexibility of the color-forming sheet 13 is increased. Furthermore, the thickness of the color-forming sheet 13 is thinner than when the color-forming sheet 13 has the base material used during manufacturing. Therefore, the portion where the color-forming sheet 13 is attached is prevented from swelling.

[0128] The transfer sheet 12 may not include the release layer 54, and the substrate 20 may be configured to be peelable from the rugged-structure layer 30 by adjusting the materials. For example, the substrate 20 may contain a release agent, or the materials of the substrate 20 and the rugged-structure layer 30 may be selected so that the adhesion between the substrate 20 and the rugged-structure layer 30 is low.

[0129] Furthermore, when transferring the color-developing sheet 13, heating and pressure, application of water pressure, ultraviolet irradiation, etc. may be performed. Such stimuli applied during transfer may cause the releasability of the substrate 20 and the adhesiveness of the adhesive layer 53 to appear. For example, the adhesive layer 53 may be formed from a thermoplastic resin that functions as a heat-sealing agent, such as polyethylene, polyvinyl acetate, acrylic, polyamide, polyester, polypropylene, or polyurethane. In such a form, the adhesiveness of the adhesive layer 53 appears when heated.

[0130] The shape and material of the adherend to which the color-developing sticker 11 or color-developing sheet 13 is attached are not particularly limited, and the adherend may be, for example, a resin molded product such as a card or a three-dimensional object, or may be paper. In short, the adherend may have a surface to which the adhesive layers 51, 53 can adhere.

[0131] Furthermore, even if the absorbing layers 50, 52 do not absorb all light in the visible range, as long as they have light-absorbing properties that absorb at least a portion of the light that passes through the multilayer film layer 40, it is possible to suppress a decrease in color visibility due to reflected light compared to a case in which such a light-absorbing layer is not provided. For example, the absorbing layers 50, 52 may be layers containing a pigment of a color corresponding to the wavelength range of light that passes through the multilayer film layer 40. However, if the absorbing layers 50, 52 are black layers containing a black pigment, there is no need to adjust the color according to the wavelength range of the transmitted light, and the absorbing layers 50, 52 absorb light in a wide wavelength range, so that a decrease in color visibility due to reflected light can be suppressed simply and preferably.

[0132] As described above, according to the above embodiment, the following effects can be obtained. (1) Because the multilayer film layer 40 is laminated on an uneven structure consisting of multiple convex portions 31, reflected light in a specific wavelength range that is intensified by interference in the multilayer film layer 40 is scattered and emitted in various directions. Furthermore, because the multiple convex portions 31 include first convex portions 32 and second convex portions 33, the reflected light is further scattered by the minute convex portions 34, 35 on the surface of the convex portions, thereby increasing the intensity of the reflected light at each observation angle. Therefore, a specific color corresponding to the wavelength range of the reflected light intensified by the multilayer film layer 40 can be observed at a wide observation angle, and the observed specific color becomes more vivid.

[0133] Furthermore, since the first convex portions 32 and the second convex portions 33 are adjacent to each other, it is possible to prevent unevenness in the arrangement of the first convex portions 32 and the second convex portions 33. Therefore, it is possible to prevent unevenness in brightness from occurring within the surface of the color-producing structure 10.

[0134] (2) The difference between the maximum height Rz1 on the surface of the first convex portions 32 and the maximum height Rz2 on the surface of the second convex portions 33 is 0.01 μm or more. This makes the differences in shape and scattering function between the first convex portions 32 and the second convex portions 33 clear, making it possible to suitably adjust the period of the periodic structure and the scattering intensity by utilizing this. Furthermore, because the difference between the maximum height Rz1 and the maximum height Rz2 is 5.0 μm or less, the height of the irregularities on the surface of the second convex portions 33 is prevented from becoming excessively large, making it easier to form the second convex portions 33.

[0135] (3) In a plan view along the thickness direction of the concave-convex structure layer 30, the plurality of convex portions 31 are arranged in a two-dimensional lattice pattern. According to the above configuration, it is easy to design the arrangement of the plurality of convex portions 31 and to form the plurality of convex portions 31. In addition, it is easy to design the arrangement of the first convex portions 32 and the second convex portions 33.

[0136] (4) If the arrangement of the convex portions 31 includes a row of a plurality of first convex portions 32 and a row of a plurality of second convex portions 33, it is possible to generate anisotropy in the region where scattering is increased on the surface of the color-forming structure 10. Furthermore, since the first convex portions 32 or the second convex portions 33 can be formed continuously for each row, the efficiency of forming the convex portions 31 can be improved.

[0137] (5) In the arrangement of the convex portions 31, if a row consisting of a plurality of first convex portions 32 and a row consisting of a plurality of second convex portions 33 are arranged in a predetermined order, it is more preferable to generate anisotropy in the area where scattering is increased within the surface of the color-forming structure 10.

[0138] (6) If the arrangement of the convex portions 31 includes a row in which the first convex portions 32 and the second convex portions 33 are arranged in a predetermined order, it is possible to arrange areas of increased scattering isotropically within the surface of the color-forming structure 10.

[0139] (7) When the period Px of the arrangement of the convex portions 31 in a row consisting of a plurality of convex portions 31 is taken as the reference period, if the positions of the convex portions 31 in adjacent rows in the direction in which the rows extend are shifted by 1 / 2 of the reference period, then even if the convex portions 31 are large, the visibility of a lattice pattern on the color-producing structure 10 is suppressed.

[0140] (8) If the shape of the convex portions 31 in the plan view is a square or a regular hexagon, the shape and arrangement of the convex portions 31 can be easily designed, and the scattering effect of the uneven structure can be suitably obtained. (9) If the ratio of the maximum length H, which is the maximum dimension in the thickness direction within the protrusions 31, to the width D of the protrusions 31 is 0.1 or more and 1.0 or less, reflection within the protrusions 31 is suppressed, thereby suppressing the emission of light in a wavelength range different from the reflected light enhanced by the multilayer film layer 40. Therefore, the visibility of the color of the reflected light is improved.

[0141] (10) The first convex portion 32 is a convex portion having the reference surface 31S as its surface, or a convex portion having minute asperities 34 on the reference surface 31S, and the second convex portion 33 is a convex portion having minute asperities 35 on the reference surface 31S. With this configuration, the angle of the surface of the convex portion 31 with respect to the incident light tends to be non-uniform within the surface, and therefore the scattering effect due to the uneven structure can be suitably obtained.

[0142] (11) If the proportion of flat portions included in the surface of the concave-convex structure layer 30 per unit area of the surface in the plan view is 10% or less, the proportion of scattered components in the reflected light from the multilayer film layer 40 is sufficiently ensured, thereby accurately suppressing color changes due to changes in the observation angle. In addition, the proportion of specular reflection components in the reflected light from the multilayer film layer 40 is kept small, thereby reducing the strain on the eyes of the observer of the color-producing structure 10.

[0143] (12) If the color-producing structure includes the absorption layers 50, 52 located on the opposite side of the concave-convex structure layer 30 with respect to the multilayer film layer 40, it is possible to prevent light in a wavelength range different from the reflected light enhanced by the multilayer film layer 40 from being visible when viewed from the side where the concave-convex structure layer 30 is located. Therefore, it is possible to prevent a decrease in the visibility of the color of the reflected light.

[0144] (13) If the color-forming structure has adhesive layers 51, 53 located on the opposite side of the uneven structure layer 30 from the multilayer film layer 40, a color-forming structure suitable for a color-forming sticker or transfer sheet that can be attached to an adherend so that the adherend is located on the opposite side of the uneven structure layer 30 from the multilayer film layer 40 can be obtained.

[0145] (14) If the color-producing structure has an anti-reflection layer located on the opposite side of the uneven structure layer 30 from the multilayer film layer 40, the surface reflection of the color-producing structure is suppressed when viewed from the side where the uneven structure layer 30 is located, thereby preventing a decrease in the visibility of the color of the reflected light.

[0146] [Variations] The plurality of protrusions 31 may include three or more types of protrusions with different surface roughnesses. In short, it is sufficient that at least one of the plurality of protrusions 31 adjacent to a first protrusion 32 is a second protrusion 33 having a greater maximum height Rz than the first protrusion 32. If the maximum height Rz of the first protrusion 32 and the second protrusion 33 is 0.01 μm or more, it can be said that the surface roughnesses of these protrusions are different from each other.

[0147] In the above embodiment, an example of application of the color-developing structure has been described in which the structure is observed from the side of the multilayer film layer 40 where the relief-structure layer 30 is located. Alternatively, the color-developing structure may be used so as to be observed from the side of the relief-structure layer 30 where the multilayer film layer 40 is located. In this case, an absorption layer or an adhesive layer may be provided on the side of the relief-structure layer 30 opposite the multilayer film layer 40. Furthermore, the relief-structure layer 30 or the substrate 20 may have a function of absorbing light transmitted through the multilayer film layer 40.

[0148] In the above embodiment, an example was given in which a multilayer film layer 40 was laminated as an optical layer on the concave-convex structure layer 30. Alternatively, a single film layer and a reflective layer may be laminated on the concave-convex structure layer 30. In this case, the optical layer is composed of the single film layer and the reflective layer. In short, the optical layer may be a laminated film that is located on the concave-convex structure, has a surface shape that follows the concave-convex structure, and emits reflected light that is enhanced by interference.

[0149] Specifically, when the color-producing structure is observed from the side where the concave-convex structure layer 30 is located relative to the optical layer, a monolayer film layer is laminated on the concave-convex structure layer 30, and a reflective layer is laminated on the monolayer film layer. The monolayer film layer is a layer consisting of a single thin film made of a dielectric. When light is incident on the monolayer film layer, the monolayer film layer emits reflected light due to thin film interference. That is, light reflected at the interfaces between the front and back of the monolayer film layer causes interference, resulting in the emission of light in an enhanced wavelength range. The material and thickness of the monolayer film layer may be selected depending on the desired color to be produced by the color-producing structure. Examples of materials for the monolayer film layer include inorganic oxides, inorganic nitrides, and inorganic oxynitrides. The reflective layer is a reflective film that enhances the reflection of light in a wavelength range enhanced by interference at the interface between the monolayer film layer and the reflective layer. Examples of materials for the reflective layer include metals.

[0150] The wavelength range of light reflected by single-layer thin-film interference does not have as sharp a peak as the wavelength range of light reflected by multilayer interference. However, by designing the single-layer film layer so that the wavelength range of reflected light includes the edge of the visible region and beyond, or by adjusting the composition ratio of the single-layer film layer so that the single-layer film layer absorbs light in part of the visible region, a specific color can be visually recognized by the observer as reflected light from the single-layer film layer. Furthermore, the uneven structure of the uneven structure layer 30 scatters the reflected light from the single-layer film layer, allowing the specific color to be vividly observed over a wide observation angle.

[0151] In addition to the layers described in the above embodiment, the color-developing structure may include other layers, such as a layer for improving adhesion between these layers or a layer having an ultraviolet absorbing function. The concave-convex structure of the concave-convex structure layer 30 may be composed of multiple recesses recessed relative to the optical layer. That is, the concave-convex structure may be composed of multiple concave-convex elements that are either convex portions or recesses. When the concave-convex elements are recesses, the multiple recesses include a first recess that is a first concave-convex element and a second recess that is a second concave-convex element, and the maximum height Rz2 on the surface of the second recess is greater than the maximum height Rz1 on the surface of the first recess. The surface of the recess is the inner surface of the recess. The arrangement of the first recess and the second recess is the same as the arrangement of the first convex portions 32 and the second convex portions 33. The shape of the recess in plan view is the same as the shape of the convex portions 31. That is, the width of the recess in plan view may be 10 μm or more and 100 μm or less. The depth of the recess is the same as the height of the convex portions 31. The height of the convex portions 31 and the depth of the recess are the dimensions of the concave-convex elements along the thickness direction of the concave-convex structure layer 30.

[0152] [Example] The above-mentioned color-developing structure will be described using specific examples and comparative examples. Example 1 As described above with reference to Figures 10 and 11, a mold for forming the concave-convex structure layer was formed by cutting, and a concave-convex structure layer made of acrylic resin was formed by extrusion molding using this mold. The mold was formed so that the convex portions in the concave-convex structure layer had a square shape with a width D of 45 μm in plan view, multiple convex portions were arranged in a square lattice pattern with no gaps, and each row of convex portions included a row of first convex portions and a row of second convex portions, with the difference between the maximum height Rz1 of the first convex portions and the maximum height Rz2 of the second convex portions being 0.01 μm. When forming the mold, recesses corresponding to the convex portions were cut in an arc from the edge of the square region to the center, with the depth continuously changing, and the recess depth in the center of the square region was 5 μm. The recesses corresponding to the second convex portions were formed using a cutting tool with a rougher surface than the recesses corresponding to the first convex portions.

[0153] Next, five 60 nm thick TiO thin films and five 80 nm thick SiO thin films were alternately stacked on the concave-convex structure layer using a vacuum deposition method, to obtain the color-developing structure of Example 1. The TiO thin films were the high refractive index layers, and the SiO thin films were the low refractive index layers.

[0154] Example 2 The color-developing structure of Example 2 was obtained using the same materials and process as in Example 1, except that when preparing the mold, the cutting tool was changed so that the difference between the maximum height Rz1 of the first convex portion and the maximum height Rz2 of the second convex portion was 0.10 μm.

[0155] Example 3 The color-developing structure of Example 3 was obtained using the same materials and process as in Example 1, except that when preparing the mold, the cutting tool was changed so that the difference between the maximum height Rz1 of the first convex portion and the maximum height Rz2 of the second convex portion was 0.50 μm.

[0156] Example 4 The color-developing structure of Example 4 was obtained using the same materials and process as in Example 1, except that when preparing the mold, the cutting tool was changed so that the difference between the maximum height Rz1 of the first convex portion and the maximum height Rz2 of the second convex portion was 1.00 μm.

[0157] Example 5 The color-developing structure of Example 5 was obtained using the same materials and process as in Example 1, except that when preparing the mold, the cutting tool was changed so that the difference between the maximum height Rz1 of the first convex portion and the maximum height Rz2 of the second convex portion was 1.50 μm.

[0158] Example 6 The color-developing structure of Example 6 was obtained using the same materials and process as in Example 1, except that when preparing the mold, the cutting tool was changed so that the difference between the maximum height Rz1 of the first convex portion and the maximum height Rz2 of the second convex portion was 3.00 μm.

[0159] (Comparative Example) The color structure of the comparative example was obtained using the same materials and processes as in the example, except that all recesses were formed using a single cutting tool when making the mold. In the color structure of the comparative example, all of the protrusions in the concave-convex structure layer were first protrusions. That is, the maximum height Rz of the multiple protrusions in the concave-convex structure layer was constant.

[0160] (Evaluation method) The reflection characteristics of the surface reflection of the coloring structures of the example and comparative example were confirmed using an optical system that can independently set the incident angle θi and the reflection angle θr relative to the coloring structure, as shown in Fig. 14. Specifically, the incident angle θi was fixed at 30°, and the reflection spectral characteristics, i.e., the reflection intensity of each wavelength in specular reflection, was measured when the reflection angle θr was 30°.

[0161] (Evaluation results) FIG. 15 shows the measurement results of the reflection characteristics of Example 2 as an example of an embodiment and a comparative example. As shown in FIG. 15, both the example and the comparative example obtained wavelength-selective reflection spectra due to multilayer interference, i.e., reflection spectra with peaks near 450 nm to 500 nm. However, in the peak wavelength range, the reflection intensity of the example was clearly lower than that of the comparative example. This indicates that the specular reflection intensity of the example was lower than that of the comparative example, and the scattering effect of the reflected light was enhanced. Therefore, the intensity of the reflected light was enhanced at observation angles other than specular reflection. This suggests that blue light enhanced by the multilayer layer can be vividly observed over a wide observation angle.

[0162] Table 1 shows the evaluation results of the scattering effect based on the measurement results of the reflection characteristics for each example and comparative example. In the evaluation of the scattering effect, a case where the reflection intensity was smaller than that of the comparative example in the peak wavelength range, i.e., the wavelength range intensified by multilayer film interference, around 450 nm to 500 nm, and the reflection intensity was equivalent to that of the comparative example in the wavelength range of 600 nm or more, was marked as "◯". A case where the reflection intensity was smaller than that of the comparative example in the range of 450 nm to 500 nm and also smaller than that of the comparative example in the wavelength range of 600 nm or more was marked as "△". A case where the reflection intensity was equivalent to or greater than that of the comparative example in the range of 450 nm to 500 nm, and the reflection intensity was equivalent to that of the comparative example in the wavelength range of 600 nm or more, was marked as "X".

[0163] [Table 1]

[0164] As shown in Table 1, an increase in the scattering effect in the peak wavelength range was confirmed in all of Examples 1 to 6. For Example 6, a decrease in specular reflection intensity, i.e., an increase in the scattering effect, was confirmed even in wavelength ranges other than the peak wavelength range.

[0165] In wavelength ranges other than the peak wavelength range, the reflection intensity is small to begin with, so even if the reflected light is scattered, the effect is small, and no significant decrease in specular reflection intensity is observed in Examples 1 to 5. On the other hand, in Example 6, the surface irregularities of the second convex portion are large, so the scattering effect is large, and it is thought that a decrease in specular reflection intensity was observed even in wavelength ranges other than the peak wavelength range. When the appearances of the Examples and Comparative Examples were observed, Example 6 was brighter than the Comparative Examples, but had a slightly whitish blue color compared to the other Examples. [Explanation of symbols]

[0166] 10...Coloring structure 11...Coloring sticker 12...Transfer sheet 13...Coloring sheet 20...Base material 30...Uneven structure layer 31...Convex part 31S…Reference surface 32...First convex part 33...Second convex part 34...First minute unevenness 35...Second minute convex part 40…Multilayer film layer 41...High refractive index layer 42...Low refractive index layer 50, 52...Absorption layer 51,53...adhesive layer 54...peeling layer 60...Resin sheet 100...Mold 101...recess 110...Cutting tools 200...Extrusion molding machine 210...T die 220...Roll

Claims

1. a concave-convex structure layer having a concave-convex structure on its surface, the concave-convex structure being composed of a plurality of concave-convex elements, which are convex portions or concave portions; an optical layer that is a laminated film positioned on the concave-convex structure, has a surface shape that follows the concave-convex structure, and emits reflected light that is intensified by interference, In a plan view of the concave-convex structure seen from a direction along the thickness direction of the concave-convex structure layer, the width of the concave-convex elements is 10 μm or more and 100 μm or less, the plurality of uneven elements include a first uneven element and a second uneven element; The surface roughness of the second uneven element is a parameter measured in accordance with the measurement method of maximum height Rz specified in JIS B 0601-2001, and is a maximum height Rz2; Regarding the surface roughness of the first uneven element, a parameter measured in accordance with the measurement method of maximum height Rz specified in JIS B 0601-2001 is a maximum height Rz1, The maximum height Rz2 is greater than the maximum height Rz1, At least one of the plurality of uneven elements adjacent to the first uneven element is the second uneven element. Chromogenic structure.

2. The difference between the maximum height Rz2 and the maximum height Rz1 is 0.01 μm or more and 5.0 μm or less. The color-forming structure according to claim 1 .

3. In the plan view, the plurality of concave and convex elements are arranged in a two-dimensional lattice pattern. The color-forming structure according to claim 1 or 2.

4. The two-dimensional lattice-like arrangement of the concave-convex elements includes a row of a plurality of the first concave-convex elements and a row of a plurality of the second concave-convex elements. The color-forming structure according to claim 3 .

5. In the two-dimensional lattice-like arrangement of the concave-convex elements, the row of the plurality of first concave-convex elements and the row of the plurality of second concave-convex elements are arranged in a predetermined order. The color-forming structure according to claim 4 .

6. The two-dimensional lattice-like arrangement of the concave-convex elements includes a row in which the first concave-convex elements and the second concave-convex elements are arranged in a predetermined order. The color-forming structure according to claim 3 .

7. In the two-dimensional lattice-like arrangement of the concave-convex elements, the period of the arrangement of the concave-convex elements in a row consisting of a plurality of the concave-convex elements is a reference period, and in adjacent rows, the positions of the concave-convex elements in the extending direction of the row are shifted by 1 / 2 of the reference period. The color-developing structure according to any one of claims 3 to 6.

8. The shape of the concave-convex elements in the plan view is a square or a regular hexagon. The color-developing structure according to any one of claims 1 to 7.

9. The ratio of the maximum dimension of the uneven element along the thickness direction to the width of the uneven element is 0.1 or more and 1.0 or less. The color-forming structure according to any one of claims 1 to 8.

10. A reference surface is a surface that is virtually set within the uneven element, the height of which increases from the end portion of the uneven element toward the center portion in the plan view, and which forms a curve in a cross section along the thickness direction. The first uneven element is a convex portion that has the reference surface as its surface, or a convex portion that has minute concaves and convexes on the reference surface, and the second uneven element is a convex portion that has minute concaves and convexes on the reference surface. The color-forming structure according to any one of claims 1 to 9.

11. The proportion of flat portions included in the surface of the concave-convex structure layer per unit area of the surface in a plan view is 10% or less. The color-forming structure according to any one of claims 1 to 10.

12. The optical layer is a laminate of a plurality of dielectric thin films, and the refractive indexes of the adjacent dielectric thin films in the optical layer are different from each other. The color-forming structure according to any one of claims 1 to 11.

13. an absorbing layer located on the opposite side of the optical layer from the concave-convex structure layer, The absorption layer has a light absorption property of absorbing at least a part of the light transmitted through the optical layer. The color-forming structure according to claim 12.

14. an adhesive layer located on the opposite side of the optical layer from the concave-convex structure layer, The outermost surface of the color-developing structure is included in the adhesive layer. The color-forming structure according to claim 12 or 13.

15. an antireflection layer located on the opposite side of the concave-convex structure layer from the optical layer; The color-forming structure according to any one of claims 12 to 14.

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