Colloidal crystal structures and articles with colloidal crystal structures

Abstract

This invention provides a colloidal crystal structure that offers both high individual identification and decorative functions. [Solution] A colloidal crystal structure 1 comprising a base material 10, a particle fixing layer 20 provided on one main surface side of the base material 10, and a plurality of colloidal particles 30 provided inside the particle fixing layer 20, wherein the plurality of colloidal particles 30 are embedded in the particle fixing layer 20 and are arranged apart from each other along a plane direction perpendicular to the thickness direction of the particle fixing layer 20, forming a plurality of types of two-dimensional crystals, and when viewed from the thickness direction, the directions of the axes of symmetry along the plane direction of the plurality of types of two-dimensional crystals are different from each other, and the average particle size of the plurality of colloidal particles 30 is 1 μm or more.

Description

Technical Field

[0001] The present invention relates to a colloidal crystal structure and an article with a colloidal crystal structure.

Background Art

[0002] Patent Document 1 discloses an immobilized two-dimensional colloidal crystal in which a colloidal crystal composed of a single layer is immobilized by a resin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The immobilized two-dimensional colloidal crystal described in Patent Document 1 is said to be used in the optical field such as a substitute for a two-dimensional diffraction grating. And when the immobilized two-dimensional colloidal crystal described in Patent Document 1 is irradiated with light (laser light), a diffraction pattern derived from the colloidal crystal appears.

[0005] The inventors are considering using the diffraction pattern of a colloidal crystal structure, such as the immobilized two-dimensional colloidal crystal described in Patent Document 1, which exhibits a diffraction pattern originating from the two-dimensional crystal composed of colloidal particles when irradiated with light, as an indicator for individual identification of each colloidal crystal structure. For example, the inventors believe that if a colloidal crystal structure is attached to an object, it will be possible to identify the object by detecting and confirming the diffraction pattern of the colloidal crystal structure. In this way, the inventors are considering imbuing colloidal crystal structures with individual identification functionality. In considering imbuing colloidal crystal structures with individual identification functionality, the inventors believe it is important to enhance the uniqueness of the diffraction pattern of the colloidal crystal structure.

[0006] In contrast, the immobilized two-dimensional colloidal crystal described in Patent Document 1 only mentions diffraction patterns derived from a six-fold symmetric crystal structure as examples of diffraction patterns originating from the colloidal crystal, and therefore lacks uniqueness in the diffraction pattern. As a result, the diffraction pattern of the immobilized two-dimensional colloidal crystal described in Patent Document 1 may not be easily used as an indicator for individual identification.

[0007] Furthermore, in addition to imparting individual identification functionality to the colloidal crystal structure, the inventors are also considering imparting decorative functionality, such as decorating an article with structural color derived from the colloidal particles of the colloidal crystal structure when the colloidal crystal structure is attached to the article.

[0008] In contrast, the immobilized two-dimensional colloidal crystal described in Patent Document 1 addresses the challenge of providing a two-dimensional colloidal crystal whose crystal structure is not easily disturbed, and therefore, it is preferable to reduce the particle size of the colloidal particles. As a result, when light is irradiated onto the immobilized two-dimensional colloidal crystal described in Patent Document 1, both the intensity of the diffracted light produced by the diffraction of incident light by the colloidal particles and the intensity of the scattered light produced by the scattering of incident light by the colloidal particles are low, which may make it difficult to see the structural color originating from the colloidal particles.

[0009] Based on the above, it can be said that the immobilized two-dimensional colloidal crystal described in Patent Document 1 has room for improvement in terms of enhancing both individual identification and decorative functions.

[0010] The present invention was made to solve the above-mentioned problems and aims to provide a colloidal crystal structure that has both high individual identification and decorative functions. Furthermore, the present invention aims to provide an article with a colloidal crystal structure attached to an article. [Means for solving the problem]

[0011] The colloidal crystal structure of the present invention comprises a substrate, a particle immobilization layer provided on one main surface side of the substrate, and a plurality of colloidal particles provided inside the particle immobilization layer, wherein the plurality of colloidal particles are embedded in the particle immobilization layer and are arranged apart from each other along a plane direction perpendicular to the thickness direction of the particle immobilization layer, forming a plurality of types of two-dimensional crystals, wherein when viewed from the thickness direction, the directions of the axes of symmetry along the plane direction of the plurality of types of two-dimensional crystals are different from each other, and the average particle size of the plurality of colloidal particles is 1 μm or more.

[0012] The article with a colloidal crystal structure of the present invention is characterized by comprising a target article and a colloidal crystal structure of the present invention attached to the target article. [Effects of the Invention]

[0013] According to the present invention, a colloidal crystal structure with high individual identification and decorative functions can be provided. Furthermore, according to the present invention, an article with a colloidal crystal structure can be provided, having a configuration in which the above-mentioned colloidal crystal structure is attached to an article. [Brief explanation of the drawing]

[0014] [Figure 1]Figure 1 is a schematic plan view showing an example of a colloidal crystal structure according to Embodiment 1 of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing a first example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 3] Figure 3 is a schematic plan view showing an example of a diffraction pattern originating from a two-dimensional crystal when light is irradiated onto the colloidal crystal structure shown in Figures 1 and 2. [Figure 4] Figure 4 is a schematic cross-sectional view showing a second example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 5] Figure 5 is a schematic cross-sectional view showing a third example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 6] Figure 6 is a schematic cross-sectional view showing a fourth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 7] Figure 7 is a schematic cross-sectional view showing a fifth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 8] Figure 8 is a schematic cross-sectional view showing a sixth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 9] Figure 9 is a schematic cross-sectional view showing the seventh example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 10] Figure 10 is a schematic cross-sectional view showing the eighth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 11] Figure 11 is a schematic cross-sectional view showing the ninth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 12] Figure 12 is a schematic cross-sectional view showing the tenth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 13] Figure 13 is a schematic cross-sectional view showing the 11th example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. [Figure 14] Figure 14 is a schematic, enlarged plan view showing an example of a colloidal crystal structure according to Embodiment 2 of the present invention. [Figure 15] FIG. 15 is a plan view schematically showing an example of a diffraction pattern derived from a two-dimensional crystal when the colloidal crystal structure shown in FIG. 14 is irradiated with light. [Figure 16] FIG. 16 is a cross-sectional view schematically showing an example of an article with a colloidal crystal structure according to Embodiment 3 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, the colloidal crystal structure of the present invention and an article with the colloidal crystal structure of the present invention will be described. Note that the present invention is not limited to the following configurations, and may be appropriately modified without departing from the gist of the present invention. Also, combinations of a plurality of the individual preferred configurations described below are also within the scope of the present invention.

[0016] In this specification, unless otherwise specified, terms indicating the relationship between elements (e.g., "parallel", "perpendicular", etc.) and terms indicating the shape of elements do not only mean the strictly literal aspect, but also mean a substantially equivalent range, for example, a range including a difference of about several percent.

[0017] [Colloidal Crystal Structure] The colloidal crystal structure of the present invention includes a substrate, a particle fixing layer provided on one main surface side of the substrate, and a plurality of colloidal particles provided inside the particle fixing layer. The plurality of colloidal particles are buried in the particle fixing layer and are arranged side by side while being separated from each other along a plane direction perpendicular to the thickness direction of the particle fixing layer, constituting a plurality of types of two-dimensional crystals. When viewed from the thickness direction, the directions of the symmetry axes of the plurality of types of two-dimensional crystals along the plane direction are different from each other, and the average particle diameter of the plurality of colloidal particles is 1 μm or more.

[0018] In the colloidal crystal structure of the present invention, multiple colloidal particles are embedded in a particle-fixed layer and arranged apart from each other along a planar direction perpendicular to the thickness direction of the particle-fixed layer, thereby forming multiple types of two-dimensional crystals. As a result, when light is irradiated onto the colloidal crystal structure of the present invention, diffraction patterns originating from the multiple types of two-dimensional crystals composed of colloidal particles appear.

[0019] Furthermore, in the colloidal crystal structure of the present invention, when viewed from the thickness direction, the directions of the symmetry axes along the plane directions of multiple types of two-dimensional crystals are different from each other. Therefore, the diffraction pattern of the colloidal crystal structure of the present invention includes not only the symmetry of the two-dimensional crystals but also the direction of the symmetry axes of the two-dimensional crystals as parameters. Moreover, in the colloidal crystal structure of the present invention, the directions of the symmetry axes of multiple types of two-dimensional crystals are different from each other. Therefore, the diffraction pattern of the colloidal crystal structure of the present invention can be indexed not only by the combination of the symmetry and symmetry axis direction in each individual two-dimensional crystal, but also by the combination of the symmetry axis directions in multiple types of two-dimensional crystals, thus increasing its uniqueness. This enhances the individual identification function of the colloidal crystal structure of the present invention.

[0020] For example, if multiple colloidal crystal structures containing the colloidal crystal structure of the present invention exist, the diffraction pattern of the colloidal crystal structure of the present invention can be easily used as an indicator for individual identification to distinguish the colloidal crystal structure of the present invention from the multiple colloidal crystal structures. Therefore, if the colloidal crystal structure of the present invention is attached to an object, the object can be easily identified by detecting and confirming the diffraction pattern of the colloidal crystal structure of the present invention.

[0021] Furthermore, in the colloidal crystal structure of the present invention, the average particle size of the multiple colloidal particles is 1 μm or larger. As a result, when light is irradiated onto the colloidal crystal structure of the present invention, both the intensity of the diffracted light produced by the diffraction of incident light by the colloidal particles and the intensity of the scattered light produced by the scattering of incident light by the colloidal particles are increased, making the structural color (colored) derived from the colloidal particles more visible. Therefore, when the colloidal crystal structure of the present invention is attached to an object, it becomes possible to decorate the object with the structural color derived from the colloidal particles of the colloidal crystal structure of the present invention. This enhances the decorative function of the colloidal crystal structure of the present invention.

[0022] Based on the above, the colloidal crystal structure of the present invention makes it possible to realize a colloidal crystal structure that has both high individual identification function and decorative function.

[0023] The following describes embodiments of the colloidal crystal structure of the present invention.

[0024] The embodiments described below are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Except for Embodiment 1, descriptions of matters common to Embodiment 1 are omitted, and the differences are mainly described. In particular, similar effects and benefits due to similar configurations are not mentioned sequentially for each embodiment.

[0025] The drawings shown below are schematic representations, and their dimensions, aspect ratios, and scales may differ from those of the actual product.

[0026] <Embodiment 1> In the colloidal crystal structure of Embodiment 1 of the present invention, multiple types of two-dimensional crystals are included, which have a six-fold symmetry when viewed from the thickness direction.

[0027] Figure 1 is a schematic plan view showing an example of a colloidal crystal structure according to Embodiment 1 of the present invention. Figure 2 is a schematic cross-sectional view showing a first example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1. Figure 3 is a schematic plan view showing an example of a diffraction pattern originating from a two-dimensional crystal when light is irradiated onto the colloidal crystal structure shown in Figures 1 and 2.

[0028] The colloidal crystal structure 1 shown in Figures 1 and 2 comprises a substrate 10, a particle immobilization layer 20, and a plurality of colloidal particles 30.

[0029] The base material 10 has a first main surface 10a and a second main surface 10b that are opposite to each other in the thickness direction. The first main surface 10a of the base material 10 is the main surface of the base material 10 on the side facing the particle immobilization layer 20. The second main surface 10b of the base material 10 is the main surface of the base material 10 on the side opposite to the particle immobilization layer 20.

[0030] The particle-fixing layer 20 has a first surface 20a and a second surface 20b that are opposite to each other in the thickness direction. The first surface 20a of the particle-fixing layer 20 is the surface of the particle-fixing layer 20 that is opposite to the substrate 10. The second surface 20b of the particle-fixing layer 20 is the surface of the particle-fixing layer 20 that is on the substrate 10 side.

[0031] The particle immobilization layer 20 is provided on one main surface side of the substrate 10. In the example shown in Figure 2, the particle immobilization layer 20 is provided on the first main surface 10a side, which is one main surface of the substrate 10.

[0032] Embodiments in which the particle-fixing layer 20 is provided on the first main surface 10a side of the substrate 10 include an embodiment in which the entire second surface 20b of the particle-fixing layer 20 is in contact with the first main surface 10a of the substrate 10 (i.e., no other layer is provided between the substrate 10 and the particle-fixing layer 20), an embodiment in which a part of the second surface 20b of the particle-fixing layer 20 is in contact with the first main surface 10a of the substrate 10 (i.e., another layer is provided in part between the substrate 10 and the particle-fixing layer 20), and an embodiment in which the particle-fixing layer 20 is present on the first main surface 10a side of the substrate 10, but the second surface 20b of the particle-fixing layer 20 is not in contact with the first main surface 10a of the substrate 10 (i.e., another layer is provided over the entire area between the substrate 10 and the particle-fixing layer 20).

[0033] Multiple colloidal particles 30 are arranged inside the particle immobilization layer 20.

[0034] Multiple colloidal particles 30 are embedded in the particle immobilization layer 20. This fixes the multiple colloidal particles 30 to the particle immobilization layer 20.

[0035] The statement that the colloidal particles 30 are embedded in the particle immobilization layer 20 means that, in the thickness direction of the particle immobilization layer 20 (the direction perpendicular to the plane of the paper in Figure 1, and the vertical direction in Figure 2), 90% or more of the height of the colloidal particles 30 is embedded in the particle immobilization layer 20.

[0036] In the example shown in Figure 2, the multiple colloidal particles 30 are completely embedded in the particle immobilization layer 20. As a result, the multiple colloidal particles 30 are protected by the particle immobilization layer 20.

[0037] Embodiments in which the colloidal particles 30 are completely embedded in the particle immobilization layer 20 include embodiments in which the colloidal particles 30 are in contact with the surface of the particle immobilization layer 20 from the inside, and embodiments in which the colloidal particles 30 are located inside the surface of the particle immobilization layer 20.

[0038] The multiple colloidal particles 30 are arranged spaced apart from each other along a planar direction perpendicular to the thickness direction of the particle-fixed layer 20. The multiple colloidal particles 30 are not arranged in a way that they are stacked in the thickness direction. In other words, the multiple colloidal particles 30 are arranged in a two-dimensional rather than three-dimensional manner.

[0039] Multiple colloidal particles 30 constitute multiple types of two-dimensional crystals. In the example shown in Figure 1, the multiple colloidal particles 30 constitute five types of two-dimensional crystals: two-dimensional crystal R1a, two-dimensional crystal R1b, two-dimensional crystal R1c, two-dimensional crystal R1d, and two-dimensional crystal R1e.

[0040] The two-dimensional crystals R1a, R1b, R1c, R1d, and R1e each possess a six-fold symmetry when viewed from the thickness direction.

[0041] The rotational symmetry of a two-dimensional crystal when viewed from the thickness direction can be confirmed by the diffraction pattern described later.

[0042] As described above, in the colloidal crystal structure 1, multiple colloidal particles 30 are embedded in the particle-fixed layer 20 and are arranged apart from each other along a plane direction perpendicular to the thickness direction of the particle-fixed layer 20, forming multiple types of two-dimensional crystals, in the example shown in Figure 1, two-dimensional crystals R1a, R1b, R1c, R1d, and R1e. As a result, when light is shone on the colloidal crystal structure 1, diffraction patterns originating from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e formed by the colloidal particles 30 appear, specifically, diffraction patterns with six-fold symmetry. For example, the diffraction patterns originating from each two-dimensional crystal include the six-fold symmetry diffraction patterns shown in Figure 3.

[0043] Furthermore, in colloidal crystal structure 1, when viewed from the thickness direction, the directions of the symmetry axes along the plane direction of multiple types of two-dimensional crystals are different from each other. In the example shown in Figure 1, two-dimensional crystals R1a, R1b, R1c, R1d, and R1e each have symmetry axes X1a, X1b, X1c, X1d, and X1e along their plane direction. The directions of symmetry axes X1a, X1b, X1c, X1d, and X1e are different from each other.

[0044] The axis of symmetry along the plane refers to the axis of symmetry along the plane when a two-dimensional crystal is symmetrical with respect to its thickness.

[0045] From the above, the diffraction pattern of colloidal crystal structure 1 includes not only the symmetry of the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e, but also the direction of the symmetry axes of the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e as parameters. Furthermore, in colloidal crystal structure 1, the directions of the symmetry axes of the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e are different from each other. Therefore, the diffraction pattern of colloidal crystal structure 1 can be indexed not only by the combination of symmetry and the direction of the symmetry axis in each of the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e, but also by the combination of the directions of the symmetry axes in the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e, thereby increasing its uniqueness. As a result, the individual identification function of colloidal crystal structure 1 is enhanced.

[0046] For example, if multiple colloidal crystal structures, including colloidal crystal structure 1, exist, the diffraction pattern of colloidal crystal structure 1 can be easily used as an indicator for individual identification to distinguish colloidal crystal structure 1 from the other multiple colloidal crystal structures. Therefore, by attaching colloidal crystal structure 1 to an object, the object can be easily identified by detecting and confirming the diffraction pattern of colloidal crystal structure 1.

[0047] When detecting the diffraction pattern of the colloidal crystal structure 1, light may be irradiated from a direction perpendicular to the main surface of the colloidal crystal structure 1 (incident angle: 90°), or from another direction (incident angle: other than 90°).

[0048] Furthermore, when detecting the diffraction pattern of the colloidal crystal structure 1, the diffraction pattern may be detected by irradiating the colloidal crystal structure 1 with light from a direction perpendicular to the main surface (incident angle: 90°) and detecting the diffracted light (reflection) reflected from the colloidal crystal structure 1 in a direction perpendicular to it. In this case, when detecting the diffraction pattern of the colloidal crystal structure 1, the position of the light source that irradiates the colloidal crystal structure 1 with light and the position of the detector that detects the diffracted light (reflection) reflected from the colloidal crystal structure 1 can be aligned, for example, the light source and the detector can be integrated.

[0049] Furthermore, in the colloidal crystal structure 1, the average particle size of the multiple colloidal particles 30 is 1 μm or larger. As a result, when light is irradiated onto the colloidal crystal structure 1, both the intensity of the diffracted light produced by the diffraction of incident light by the colloidal particles 30 and the intensity of the scattered light produced by the scattering of incident light by the colloidal particles 30 are increased, making the structural color (colored) derived from the colloidal particles 30 more visible. Therefore, when attaching the colloidal crystal structure 1 to an object, it becomes possible to decorate the object with the structural color derived from the colloidal particles 30 of the colloidal crystal structure 1. This enhances the decorative function of the colloidal crystal structure 1.

[0050] To be visible means that it can be visually confirmed in the visible light spectrum.

[0051] The visible light region refers to the wavelength range between 360 nm and 830 nm.

[0052] The average particle size of the multiple colloidal particles 30 is preferably 1 μm or more and 50 μm or less. In this case, the colloidal particles 30 become more visible. Furthermore, the structural color derived from the colloidal particles 30 becomes more visible. As a result, when attaching the colloidal crystal structure 1 to an object, it becomes easier to decorate the object with the structural color derived from the colloidal particles 30 of the colloidal crystal structure 1. This further enhances the decorative function of the colloidal crystal structure 1.

[0053] The average particle size of multiple colloidal particles 30 is measured using a scanning electron microscope (SEM) for 100 to 200 colloidal particles 30 out of all the colloidal particles 30 contained in the colloidal crystal structure 1.

[0054] Based on the above, colloidal crystal structure 1 makes it possible to realize a colloidal crystal structure with high individual identification and decorative functions.

[0055] The two-dimensional crystals R1a, R1b, R1c, R1d, and R1e, which constitute the colloidal particle 30, are each unique and irreproducible. Therefore, the diffraction patterns derived from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e are also unique and irreproducible. This will be explained below with an example of a manufacturing method for the colloidal crystal structure 1.

[0056] First, a colloidal dispersion is prepared in which multiple colloidal particles 30 are dispersed in a dispersion medium. In this case, the average particle size of the multiple colloidal particles 30 is set to 1 μm or larger.

[0057] The type of dispersion medium is not particularly limited. The dispersion medium may be, for example, an inorganic solvent such as water, or an organic solvent such as an alcohol.

[0058] Next, the colloidal dispersion is applied to one main surface of the substrate 10.

[0059] The method of applying the colloidal dispersion is not particularly limited. For example, the colloidal dispersion may be dropped onto one main surface of the substrate 10, or the substrate 10 may be immersed in the colloidal dispersion.

[0060] Next, the dispersion medium in the colloidal dispersion applied to one main surface of the substrate 10 is dried, leaving multiple colloidal particles 30 on that main surface of the substrate 10. Then, of the remaining multiple colloidal particles 30, all but the layer closest to the substrate 10 are washed away with a washing solution such as water. As a result, the one layer of colloidal particles 30 that is not washed away will be arranged two-dimensionally on the main surface of the substrate 10, separating from each other due to electrostatic repulsion.

[0061] Finally, a particle immobilization layer 20 is formed on one main surface of the substrate 10 so that multiple colloidal particles 30 arranged in two dimensions are embedded.

[0062] The method for forming the particle immobilization layer 20 is not particularly limited.

[0063] As a result, colloidal crystal structure 1 is manufactured.

[0064] In the colloidal crystal structure 1 manufactured by the above method, multiple colloidal particles 30 are embedded in the particle-fixed layer 20 and arranged apart from each other along a plane direction perpendicular to the thickness direction of the particle-fixed layer 20, forming two-dimensional crystals R1a, R1b, R1c, R1d, and R1e. In this case, since the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e are formed using the electrostatic repulsion force between the multiple colloidal particles 30, each one is unique and irreproducible. Therefore, the diffraction patterns originating from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e are also unique and irreproducible. In other words, a unique diffraction pattern will appear in the colloidal crystal structure 1, determined by the arrangement and particle size of the colloidal particles 30 that constitute the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e.

[0065] Because the diffraction patterns derived from its two-dimensional crystals R1a, R1b, R1c, R1d, and R1e are unique, the colloidal crystal structure 1 has high individual identification capabilities and can be used in a variety of applications.

[0066] For example, due to the individual identification function of the colloidal crystal structure 1, it can be used for security purposes such as determining the authenticity of goods. For instance, if a manufacturer, distributor, etc., attaches the colloidal crystal structure 1 to a genuine item beforehand, the authenticity of the item can be determined by checking whether the colloidal crystal structure 1 is attached to the item to be determined using the diffraction pattern.

[0067] If the colloidal crystal structure 1 is attached to a genuine article, the authenticity of the article can be determined, for example, by following the procedure below.

[0068] First, when light is shone onto the item to be judged, it is confirmed whether or not a diffraction pattern originating from a two-dimensional crystal is detected, thereby confirming whether or not a colloidal crystal structure of the same type as colloidal crystal structure 1 is attached to the item to be judged. Then, if it is determined that a colloidal crystal structure is attached to the item to be judged, it is confirmed whether or not the diffraction pattern detected from the item to be judged is identical to the unique diffraction pattern of colloidal crystal structure 1 attached to the genuine item, thereby confirming whether or not the colloidal crystal structure attached to the item to be judged is identical to colloidal crystal structure 1 attached to the genuine item. In this case, if information such as the shape, size, position, direction (angle) of the axis of symmetry along the plane direction, and what kind of diffraction pattern appears when light is shone at a certain angle is prepared in advance regarding the diffraction patterns originating from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e present in colloidal crystal structure 1, then the authenticity of the item to be judged can be determined more efficiently by checking the diffraction pattern detected from the item to be judged based on that information.

[0069] When colloidal crystal structure 1 is used for the security purposes described above, it is expected to be attached to relatively expensive items such as paintings, watches, eyewear, jewelry, and perfumes. In this case, a third party attempting to counterfeit these items would need to counterfeit not only the items themselves but also the colloidal crystal structure 1 attached to them. However, as described above, the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e of colloidal crystal structure 1 are unique and irreproducible, and the diffraction patterns derived from R1a, R1b, R1c, R1d, and R1e are also unique and irreproducible. Therefore, a third party cannot counterfeit colloidal crystal structure 1. Thus, colloidal crystal structure 1 provides a high level of anti-counterfeiting effect.

[0070] Furthermore, regarding the diffraction pattern of the colloidal crystal structure 1, the combination of the symmetry axis directions along the plane direction of the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e is unique and irreproducible. Therefore, the colloidal crystal structure 1 containing the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e can exhibit a higher anti-counterfeiting effect when used for security applications as described above.

[0071] The following describes each component of the colloidal crystal structure 1.

[0072] (base material) The substrate 10 may be dyed. In this case, the decorative function of the colloidal crystal structure 1 is more easily enhanced.

[0073] If the substrate 10 is dyed, it is preferable that the substrate 10 has light transmittance. For example, it is preferable that the substrate 10 has a light transmittance of 10% or more in the visible light region.

[0074] The base material 10 does not need to be dyed.

[0075] The base material 10 preferably has flexibility. In this case, the colloidal crystal structure 1 can be easily attached to a bent object.

[0076] The constituent materials of the base material 10 are not particularly limited and may be inorganic materials, organic materials, or hybrid materials of inorganic and organic materials.

[0077] The base material 10 may be, for example, a glass plate, a plastic plate, or the like.

[0078] (particle fixed layer) The particle immobilization layer 20 may be in contact with the substrate 10. The particle immobilization layer 20 may be in contact with the entire first main surface 10a, which is one main surface of the substrate 10, or it may be in contact with a part of the first main surface 10a, which is one main surface of the substrate 10.

[0079] The particle immobilization layer 20 may be stained. In this case, the decorative function of the colloidal crystal structure 1 is more easily enhanced.

[0080] If the particle immobilization layer 20 is stained, it is preferable that the particle immobilization layer 20 is light-transmitting. For example, it is preferable that the particle immobilization layer 20 has a light transmittance of 10% or more in the visible light region.

[0081] The particle immobilization layer 20 does not need to be stained.

[0082] Preferably, the particle immobilization layer 20 has surface conformability that can follow the surface irregularities of the object to which it is attached. In this case, even if the colloidal crystal structure 1 is attached to the object from the particle immobilization layer 20 side, bubbles (air bubbles) are less likely to form at the interface between the particle immobilization layer 20 and the object. Therefore, when light is irradiated onto the colloidal crystal structure 1, the diffracted light diffracted by the colloidal particles 30 is less likely to scatter at the interface between the particle immobilization layer 20 and the object. As a result, the intensity of the diffraction patterns originating from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e increases (becomes brighter), and the shape of the diffraction patterns improves (becomes clearer), making the diffraction patterns easier to detect.

[0083] The particle immobilization layer 20 may have a single-layer structure or a multi-layer structure.

[0084] The particle immobilization layer 20 preferably contains a resin layer. In this case, the particle immobilization layer 20 may contain only a resin layer, or it may contain other layers in addition to the resin layer.

[0085] The resin layer is preferably composed of an ultraviolet-curable resin.

[0086] The constituent materials of the resin layer are not particularly limited and may include polymer resins such as acrylic resins, epoxy resins, polyurethane resins, and polystyrene resins, as well as silicone resins, biopolymers, and the like. Among these resins, acrylic resins are preferred.

[0087] (Colloidal particles) It is preferable that the colloidal particles 30 are located on the second surface 20b of the particle immobilization layer 20, rather than on the first surface 20a. In other words, it is preferable that the distance between the colloidal particles 30 and the second surface 20b of the particle immobilization layer 20 is smaller than the distance between the colloidal particles 30 and the first surface 20a of the particle immobilization layer 20.

[0088] In the example shown in Figure 2, the colloidal particles 30 are located on the second surface 20b of the particle immobilization layer 20, rather than on the first surface 20a. Specifically, the colloidal particles 30 are in contact with the second surface 20b of the particle immobilization layer 20 from the inside. Also, in the example shown in Figure 2, the substrate 10 is in contact with the second surface 20b of the particle immobilization layer 20. Therefore, in the example shown in Figure 2, the colloidal particles 30 are in contact with the substrate 10.

[0089] Furthermore, the colloidal particles 30 may be located on the first surface 20a side of the particle immobilization layer 20, rather than on the second surface 20b. In other words, the distance between the colloidal particles 30 and the first surface 20a of the particle immobilization layer 20 may be smaller than the distance between the colloidal particles 30 and the second surface 20b of the particle immobilization layer 20.

[0090] Furthermore, the colloidal particles 30 may be located between the first surface 20a and the second surface 20b of the particle immobilization layer 20. In other words, the distance between the colloidal particles 30 and the first surface 20a of the particle immobilization layer 20 and the distance between the colloidal particles 30 and the second surface 20b of the particle immobilization layer 20 may be the same as each other.

[0091] When viewed from the thickness direction, the multiple colloidal particles 30 may be provided throughout the entire particle immobilization layer 20.

[0092] Furthermore, when viewed from the thickness direction, the multiple colloidal particles 30 may be provided in a part of the particle immobilization layer 20. In other words, when viewed from the thickness direction, the multiple colloidal particles 30 do not have to be provided in a part of the particle immobilization layer 20.

[0093] When viewed from the thickness direction, it is preferable that the multiple colloidal particles 30 are evenly distributed such that the distance (pitch) between the centers of adjacent colloidal particles 30 in the planar direction is constant. In this case, when viewed from the thickness direction, the multiple colloidal particles 30 may be evenly distributed throughout the entire particle-fixed layer 20, or they may be evenly distributed in a part of the particle-fixed layer 20.

[0094] The coefficient of variation (CV value) of the particle sizes of the multiple colloidal particles 30 is preferably 20% or less. In this case, the particle sizes of the multiple colloidal particles 30 tend to be uniform (monodispersibility increases), making it easier for the multiple colloidal particles 30 to arrange themselves to form two-dimensional crystals R1a, R1b, R1c, R1d, and R1e. As a result, when light is irradiated onto the colloidal crystal structure 1, the intensity of the diffraction patterns originating from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e increases, and the shape of the diffraction patterns improves, making the diffraction patterns easier to detect.

[0095] The coefficient of variation (CV value) of the particle sizes of multiple colloidal particles 30 can be calculated by measuring 100 to 200 colloidal particles 30 out of all the colloidal particles 30 contained in the colloidal crystal structure 1 using a scanning electron microscope (SEM). The coefficient of variation (CV value) is calculated as follows: D = 100 × (σ / D), where D is the average particle size and σ is the standard deviation.

[0096] The colloidal particles 30 may be inorganic particles or organic particles.

[0097] When the colloidal particles 30 are inorganic particles, their constituent materials are not particularly limited and may include, for example, silica, titanium oxide, alumina, gold, silver, etc. Among these, silica and titanium oxide are preferred.

[0098] When the colloidal particles 30 are organic particles, their constituent material is not particularly limited and may be polymers such as polystyrene, polyacrylic acid ester, polymethacrylic acid ester, or polyacrylonitrile. Among these, polystyrene is preferred.

[0099] The following describes the relationship between the refractive indices of each component of the colloidal crystal structure 1.

[0100] In the visible light region, it is preferable that the refractive indices of at least two components selected from the group consisting of the substrate 10, the particle immobilization layer 20, and the colloidal particles 30 are different from each other. Specifically, as follows: In the visible light region, it is preferable that the refractive indices of the substrate 10 and the particle immobilization layer 20 are different from each other. Alternatively, in the visible light region, it is preferable that the refractive indices of the substrate 10 and the colloidal particles 30 are different from each other. Alternatively, in the visible light region, it is preferable that the refractive indices of the particle immobilization layer 20 and the colloidal particles 30 are different from each other. Alternatively, in the visible light region, it is preferable that the refractive indices of the substrate 10, the particle immobilization layer 20, and the colloidal particles 30 are different from each other. In these cases, the colloidal crystal structure 1 becomes more visible, and the decorative function of the colloidal crystal structure 1 is further enhanced.

[0101] In the visible light region, it is preferable that the refractive index of the colloidal particles 30 differs from the refractive index of at least one of the substrate 10 and the particle fixing layer 20 by 0.001 or more. Specifically, this is as follows: In the visible light region, it is preferable that the refractive index of the colloidal particles 30 differs from the refractive index of the substrate 10 by 0.001 or more. Alternatively, in the visible light region, it is preferable that the refractive index of the colloidal particles 30 differs from the refractive index of the particle fixing layer 20 by 0.001 or more. Alternatively, in the visible light region, it is preferable that the refractive index of the colloidal particles 30 differs from the refractive index of the substrate 10 by 0.001 or more, and also differs from the refractive index of the particle fixing layer 20 by 0.001 or more. In these cases, the colloidal particles 30 become more visible. Furthermore, the structural color derived from the colloidal particles 30 becomes more visible. As a result, when attaching the colloidal crystal structure 1 to an article, it becomes easier to decorate the article with the structural color derived from the colloidal particles 30 of the colloidal crystal structure 1. This makes it easier to further enhance the decorative function of colloidal crystal structure 1.

[0102] In the visible light region, the refractive index of the colloidal particles 30 may be less than 0.001 in difference from the refractive index of at least one of the substrate 10 and the particle fixing layer 20.

[0103] The refractive index of the substrate 10 in the visible light region is preferably 1.3 or higher and 2.3 or lower.

[0104] The refractive index of the particle immobilization layer 20 in the visible light region is preferably 1.3 or higher and 2.3 or lower.

[0105] Furthermore, if the particle stationary layer 20 has a multilayer structure, the refractive index of the particle stationary layer 20 in the visible light region is determined as the average value of the refractive indices of the multiple layers constituting the particle stationary layer 20 in the visible light region.

[0106] The refractive index of the colloidal particles 30 in the visible light region is preferably 1.3 or higher and 2.3 or lower.

[0107] The refractive indices of the substrate 10, the particle immobilization layer 20, and the colloidal particles 30 in the visible light region are measured by the V-block method.

[0108] In the infrared region, the refractive indices of at least two components selected from the group consisting of the substrate 10, the particle immobilization layer 20, and the colloidal particles 30 may be the same. Specifically, as follows: In the infrared region, the refractive indices of the substrate 10 and the particle immobilization layer 20 may be the same. Alternatively, in the infrared region, the refractive indices of the substrate 10 and the colloidal particles 30 may be the same. Alternatively, in the infrared region, the refractive indices of the particle immobilization layer 20 and the colloidal particles 30 may be the same. Alternatively, in the infrared region, the refractive indices of the substrate 10, the particle immobilization layer 20, and the colloidal particles 30 may be the same.

[0109] In the infrared region, the refractive indices of at least two components selected from the group consisting of the substrate 10, the particle immobilization layer 20, and the colloidal particles 30 may be different from each other. Specifically, the following may apply: In the infrared region, the refractive indices of the substrate 10 and the particle immobilization layer 20 may be different from each other. Alternatively, in the infrared region, the refractive indices of the substrate 10 and the colloidal particles 30 may be different from each other. Alternatively, in the infrared region, the refractive indices of the particle immobilization layer 20 and the colloidal particles 30 may be different from each other. Alternatively, in the infrared region, the refractive indices of the substrate 10, the particle immobilization layer 20, and the colloidal particles 30 may be different from each other. In these cases, the colloidal crystal structure 1 becomes detectable in the infrared region.

[0110] The infrared region refers to the wavelength range from 830 nm upwards to 1 mm downwards.

[0111] The refractive index of the substrate 10 in the infrared region is preferably 0.4 or higher and 5.7 or lower.

[0112] The refractive index of the particle immobilization layer 20 in the infrared region is preferably 0.4 or higher and 5.7 or lower.

[0113] Furthermore, if the particle stationary layer 20 has a multilayer structure, the refractive index of the particle stationary layer 20 in the infrared region is determined as the average value of the refractive indices in the infrared region of the multiple layers constituting the particle stationary layer 20.

[0114] The refractive index of the colloidal particles 30 in the infrared region is preferably 0.4 or higher and 5.7 or lower.

[0115] The refractive indices of the substrate 10, the particle immobilization layer 20, and the colloidal particles 30 in the infrared region are measured by the V-block method.

[0116] The colloidal crystal structure 1 may or may not further have members other than the substrate 10, the particle immobilization layer 20, and the plurality of colloidal particles 30.

[0117] (Middle class) Figure 4 is a schematic cross-sectional view showing a second example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0118] As shown in Figure 4, the colloidal crystal structure 1 may further have an intermediate layer 40 that is in contact with the substrate 10 and the colloidal particles 30 between the substrate 10 and the colloidal particles 30.

[0119] Because the intermediate layer 40 is in contact with the colloidal particles 30, the colloidal particles 30 are protected not only by the substrate 10 and the particle immobilization layer 20, but also by the intermediate layer 40.

[0120] Because the intermediate layer 40 is in contact with the substrate 10 and the colloidal particles 30, the colloidal particles 30 are fixed to the substrate 10 via the intermediate layer 40. When the colloidal particles 30 are fixed to the substrate 10, for example, even if an external force is applied to the colloidal crystal structure 1, the crystal structure of the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e that constitute the colloidal particles 30 is more easily maintained. As a result, when light is irradiated onto the colloidal crystal structure 1, diffraction patterns originating from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e are more easily detected.

[0121] One way to obtain a configuration in which the intermediate layer 40 is in contact with the substrate 10 and the colloidal particles 30 between the substrate 10 and the colloidal particles 30 is, for example, to use a substrate 10 to which the intermediate layer 40 is pre-provided on one main surface when manufacturing the colloidal crystal structure 1 by the method described above, to which the colloidal dispersion containing the colloidal particles 30 is applied. When the colloidal dispersion is applied to one main surface of the substrate 10 to which the intermediate layer 40 is pre-provided, the colloidal particles 30 will be arranged two-dimensionally while adsorbed on the intermediate layer 40.

[0122] The thickness of the intermediate layer 40 is, for example, between 1 nm and 100 nm.

[0123] The intermediate layer 40 is preferably composed of a metal oxide. In this case, titanium oxide is preferred as the metal oxide.

[0124] The intermediate layer 40 may be composed of a material other than a metal oxide. For example, the intermediate layer 40 may be composed of a silane coupling agent.

[0125] Figure 5 is a schematic cross-sectional view showing a third example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0126] As shown in Figure 5, the intermediate layer 40 may further extend in the planar direction between the substrate 10 and the particle-fixing layer 20 so as to be in contact with the substrate 10 and the particle-fixing layer 20.

[0127] Figure 6 is a schematic cross-sectional view showing a fourth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0128] As shown in Figure 6, the particle immobilization layer 20 may include an adhesive layer 21 that constitutes the first surface 20a, which is the surface of the particle immobilization layer 20 opposite to the substrate 10. In this case, when attaching the colloidal crystal structure 1 to the target article from the particle immobilization layer 20 side, specifically from the first surface 20a side of the particle immobilization layer 20, the adhesive action of the adhesive layer 21 that constitutes the first surface 20a of the particle immobilization layer 20 makes it easier to firmly attach the colloidal crystal structure 1 to the target article.

[0129] Figure 7 is a schematic cross-sectional view showing a fifth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0130] The configuration shown in Figure 7 is the same as the configuration shown in Figure 4, except that the particle immobilization layer 20 includes the adhesive layer 21.

[0131] Figure 8 is a schematic cross-sectional view showing a sixth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0132] The configuration shown in Figure 8 is the same as the configuration shown in Figure 5, except that the particle immobilization layer 20 includes the adhesive layer 21.

[0133] In the examples shown in Figures 6, 7, and 8, the particle immobilization layer 20 is entirely composed of an adhesive layer 21. On the other hand, the particle immobilization layer 20 may also be composed of only a portion of the adhesive layer 21.

[0134] Figure 9 is a schematic cross-sectional view showing the seventh example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0135] As shown in Figure 9, the particle immobilization layer 20 may include, in addition to the adhesive layer 21, a layer other than the adhesive layer 21, for example, a non-adhesive layer 22. In this case, the particle immobilization layer 20 may include, in addition to the adhesive layer 21 that constitutes the first surface 20a, a non-adhesive layer 22 that constitutes the second surface 20b.

[0136] As shown in Figure 9, the colloidal particles 30 may be provided across the interface between the adhesive layer 21 and the non-adhesive layer 22.

[0137] The non-adhesive layer 22 may be, for example, the resin layer described above, which is preferably included in the particle-fixing layer 20.

[0138] The configuration shown in Figure 9 is the same as the configuration shown in Figure 7, except for the points mentioned above.

[0139] Figure 10 is a schematic cross-sectional view showing the eighth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0140] As shown in Figure 10, the colloidal particles 30 are not provided across the interface between the adhesive layer 21 and the non-adhesive layer 22, but may be embedded in the non-adhesive layer 22.

[0141] The configuration shown in Figure 10 is the same as the configuration shown in Figure 9, except for the points mentioned above.

[0142] Figure 11 is a schematic cross-sectional view showing the ninth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0143] The configuration shown in Figure 11 is the same as the configuration shown in Figure 8, except that the particle immobilization layer 20 includes an adhesive layer 21 and a non-adhesive layer 22, and the colloidal particles 30 are provided across the interface between the adhesive layer 21 and the non-adhesive layer 22.

[0144] Figure 12 is a schematic cross-sectional view showing the tenth example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0145] The configuration shown in Figure 12 is the same as the configuration shown in Figure 11, except that the colloidal particles 30 are embedded in the non-adhesive layer 22.

[0146] In the examples shown in Figures 9, 10, 11, and 12, the particle immobilization layer 20 has a two-layer structure consisting of an adhesive layer 21 and a non-adhesive layer 22, but it may also have a structure of three or more layers.

[0147] (Functional layer) Figure 13 is a schematic cross-sectional view showing the 11th example of a cross-section along the thickness direction of the colloidal crystal structure shown in Figure 1.

[0148] As shown in Figure 13, the colloidal crystal structure 1 may further have a functional layer 50 provided on at least one surface selected from the group consisting of a first surface 20a, which is the surface of the particle-fixed layer 20 opposite to the substrate 10, a second main surface 10b, which is the main surface of the substrate 10 opposite to the particle-fixed layer 20, and the interface between the substrate 10 and the particle-fixed layer 20. In the example shown in Figure 13, the functional layer 50 is provided on the second main surface 10b of the substrate 10.

[0149] The functional layer 50 may be, for example, a hard coat layer, an antifouling coat layer, or an anti-reflective coat layer. In this case, the various properties of the colloidal crystal structure 1 can be improved by the hard coat layer, the durability, abrasion resistance, and weather resistance; by the antifouling coat layer, the antifouling resistance; and by the anti-reflective coat layer, the light transmittance.

[0150] In addition, Figure 13 illustrates the case where the functional layer 50 is provided in the configuration shown in Figure 2, but the functional layer 50 may also be provided in configurations other than those shown in Figure 2, for example, in any of the configurations shown in Figures 4 to 12.

[0151] The colloidal crystal structure 1 may be provided with at least one of a cutting notch and an incision. For example, the particle immobilization layer 20 may be provided with at least one of a cutting notch and an incision. Also, the substrate 10 may be provided with at least one of a cutting notch and an incision.

[0152] If the colloidal crystal structure 1 has at least one of a notch and an incision, the colloidal crystal structure 1 becomes brittle, making it prone to damage when removed after being attached to an object. Therefore, as described above, when the colloidal crystal structure 1 is used for security purposes, it becomes difficult for a third party to remove the colloidal crystal structure 1 from a genuine object and attach it to another object (for example, a counterfeit item).

[0153] <Embodiment 2> The colloidal crystal structure of the present invention includes multiple types of two-dimensional crystals, each having four-fold symmetry when viewed from the thickness direction.

[0154] Figure 14 is a schematic, enlarged plan view showing an example of a colloidal crystal structure according to Embodiment 2 of the present invention. Figure 15 is a schematic plan view showing an example of a diffraction pattern originating from a two-dimensional crystal when light is irradiated onto the colloidal crystal structure shown in Figure 14.

[0155] In the colloidal crystal structure 2 shown in Figure 14, the multiple colloidal particles 30 constitute multiple types of two-dimensional crystals, including the two-dimensional crystal R2a, which has four-fold symmetry when viewed from the thickness direction. Although not shown in Figure 14, among these multiple types of two-dimensional crystals, the two-dimensional crystals other than the two-dimensional crystal R2a also have four-fold symmetry when viewed from the thickness direction. Furthermore, in the colloidal crystal structure 2, when viewed from the thickness direction, the directions of the symmetry axes along the plane direction of the multiple types of two-dimensional crystals, including the two-dimensional crystal R2a, are different from each other.

[0156] When light is shone on the colloidal crystal structure 2, diffraction patterns originating from multiple types of two-dimensional crystals, including the two-dimensional crystal R2a, which constitute the colloidal particles 30, appear. Specifically, four-fold symmetric diffraction patterns appear. For example, the four-fold symmetric diffraction patterns shown in Figure 15 appear as diffraction patterns originating from each of the two-dimensional crystals.

[0157] A two-dimensional crystal with four-fold symmetry (e.g., two-dimensional crystal R2a) is more difficult to realize than a two-dimensional crystal with six-fold symmetry (e.g., two-dimensional crystal R1a). Therefore, when used for security purposes as described above, colloidal crystal structure 2, which contains a two-dimensional crystal with four-fold symmetry, can exhibit a higher level of anti-counterfeiting effect compared to colloidal crystal structure 1, which contains a two-dimensional crystal with six-fold symmetry.

[0158] A two-dimensional crystal with four-fold symmetry can be realized, for example, by adjusting the thickness of the colloidal dispersion applied to one main surface of the substrate 10 when manufacturing colloidal crystal structure 2 in the same manner as colloidal crystal structure 1. For example, after applying the colloidal dispersion to one main surface of the substrate 10, the thickness of the colloidal dispersion can be changed by placing another component, such as a glass plate, on the surface of the colloidal dispersion. In this case, by changing the thickness of the other component placed on the surface of the colloidal dispersion, the weight of this component can be changed, and as a result, the thickness of the colloidal dispersion can be adjusted. When the thickness of the colloidal dispersion is within a specific range, a two-dimensional crystal with four-fold symmetry can be realized.

[0159] The colloidal crystal structure of the present invention is not limited to the above-described form, and various applications and modifications can be made within the scope of the present invention regarding the composition, manufacturing conditions, etc., of the colloidal crystal structure.

[0160] In the colloidal crystal structure of the present invention, Embodiments 1 and 2 illustrate an embodiment in which the multiple types of two-dimensional crystals present in the colloidal crystal structure of the present invention include only two-dimensional crystals having six-fold symmetry when viewed from the thickness direction in terms of the symmetry of the two-dimensional crystals (Embodiment 1), or an embodiment in which only two-dimensional crystals having four-fold symmetry when viewed from the thickness direction (Embodiment 2). The multiple types of two-dimensional crystals present in the colloidal crystal structure of the present invention may include both two-dimensional crystals having six-fold symmetry when viewed from the thickness direction and two-dimensional crystals having four-fold symmetry when viewed from the thickness direction. Furthermore, the multiple types of two-dimensional crystals present in the colloidal crystal structure of the present invention may include two-dimensional crystals having symmetries other than six-fold and four-fold symmetry when viewed from the thickness direction. In either of the above cases, it is sufficient that the directions of the symmetry axes along the plane direction of the multiple types of two-dimensional crystals are different from each other when viewed from the thickness direction.

[0161] The number of types of two-dimensional crystals present in the colloidal crystal structure of the present invention is not limited to the five types shown in Embodiment 1, but may be multiple types other than the five.

[0162] The form of the colloidal crystal structure of the present invention is not particularly limited and may be, for example, a tag, film, card, seal, etc.

[0163] [Articles with colloidal crystal structures] The article with a colloidal crystal structure of the present invention is characterized by comprising a target article and a colloidal crystal structure of the present invention attached to the target article.

[0164] Even in configurations where the colloidal crystal structure of the present invention is attached to an article, such as an article with the colloidal crystal structure of the present invention, both the individual identification function and the decorative function of the colloidal crystal structure of the present invention are high.

[0165] The following describes embodiments of the article with a colloidal crystal structure according to the present invention.

[0166] <Embodiment 3> In the colloidal crystal structure article of Embodiment 3 of the present invention, the colloidal crystal structure is attached to the article from the particle stationary layer side.

[0167] Figure 16 is a schematic cross-sectional view showing an example of an article with a colloidal crystal structure according to Embodiment 3 of the present invention.

[0168] The colloidal crystal structure article 101 shown in Figure 16 comprises the target article 110 and the colloidal crystal structure 1 (see Figures 1 and 2).

[0169] The colloidal crystal structure 1 is attached to the target article 110. In the example shown in Figure 16, the colloidal crystal structure 1 is attached to the target article 110 from the particle immobilization layer 20 side, specifically from the first surface 20a side of the particle immobilization layer 20. In this case, as described above, if the particle immobilization layer 20 includes an adhesive layer 21 that constitutes the first surface 20a (see Figures 6-12), the adhesive action of the adhesive layer 21 that constitutes the first surface 20a of the particle immobilization layer 20 makes it easier to firmly attach the colloidal crystal structure 1 to the target article 110.

[0170] The type of item 110 is not particularly limited. When the colloidal crystal structure 1 is used for the security purposes described above, the item 110 may be, for example, a painting, a watch, eyewear, jewelry, perfume, or the like.

[0171] Even in configurations where the colloidal crystal structure 1 is attached to the target article 110, such as article 101 with a colloidal crystal structure, both the individual identification function and the decorative function of the colloidal crystal structure 1 are high.

[0172] The colloidal crystal structure article of the present invention is not limited to the above-described form, and various applications and modifications can be made within the scope of the present invention regarding the composition, manufacturing conditions, etc., of the colloidal crystal structure article.

[0173] In the article with the colloidal crystal structure of the present invention, Embodiment 3 illustrates an embodiment in which the colloidal crystal structure of the present invention is attached to the article from the particle stationary layer side. In the article with the colloidal crystal structure of the present invention, the colloidal crystal structure of the present invention may also be attached to the article from the substrate side.

[0174] In the article with the colloidal crystal structure of the present invention, Embodiment 3 illustrates an embodiment in which the colloidal crystal structure of the present invention is attached to a part of the surface of the article on the colloidal crystal structure side (the top surface in Figure 16). In the article with the colloidal crystal structure of the present invention, the colloidal crystal structure of the present invention may be attached to the entire surface of the article on the colloidal crystal structure side.

[0175] In an article with a colloidal crystal structure of the present invention, if the colloidal crystal structure of the present invention is attached to the entire surface of the article on the colloidal crystal structure side, the periphery of the colloidal crystal structure of the present invention may be along the periphery of the article. In this case, the periphery of the colloidal crystal structure of the present invention does not need to be strictly along (overlapping) the periphery of the article, but only needs to be substantially along the periphery of the article. For example, the periphery of the colloidal crystal structure of the present invention may be located inside the periphery of the article, or it may be located outside the periphery of the article. [Explanation of Symbols]

[0176] 1, 2 Colloidal crystal structures 10 Base material 10a First main surface of the substrate 10b Second main surface of the substrate 20 Particle fixed layer 20a First surface of the particle immobilization layer 20b Second surface of the particle immobilization layer 21 Adhesive layer 22 Non-adhesive layer 30 colloidal particles 40 Middle Class 50 Functional Layers 101 Articles with colloidal crystal structures 110 Target items R1a, R1b, R1c, R1d, R1e, R2a 2D crystal X1a, X1b, X1c, X1d, X1e: Axes of symmetry

Claims

1. Substrate and A particle-fixing layer provided on one main surface side of the substrate, The particle immobilization layer comprises a plurality of colloidal particles provided inside the particle immobilization layer, Multiple colloidal particles, while embedded in the particle-fixed layer, are arranged apart from each other along a planar direction perpendicular to the thickness direction of the particle-fixed layer, thereby forming multiple types of two-dimensional crystals. When viewed from the thickness direction, the directions of the axes of symmetry along the plane direction of the multiple types of the two-dimensional crystals are different from each other. A colloidal crystal structure characterized in that the average particle size of a plurality of colloidal particles is 1 μm or more.

2. The colloidal crystal structure according to claim 1, wherein the average particle size of the plurality of colloidal particles is 1 μm or more and 50 μm or less.

3. The colloidal crystal structure according to claim 1 or 2, wherein the particle immobilization layer is in contact with the substrate.

4. The colloidal crystal structure according to claim 1 or 2, further comprising an intermediate layer in contact with the substrate and the colloidal particles between the substrate and the colloidal particles.

5. The colloidal crystal structure according to claim 4, wherein the intermediate layer further extends in the planar direction between the substrate and the particle immobilization layer so as to be in contact with the substrate and the particle immobilization layer.

6. The colloidal crystal structure according to any one of claims 1 to 5, wherein the particle immobilization layer includes an adhesive layer that constitutes the surface of the particle immobilization layer opposite to the substrate.

7. The colloidal crystal structure according to any one of claims 1 to 6, wherein the multiple types of two-dimensional crystals include two-dimensional crystals having six-fold symmetry when viewed from the thickness direction.

8. The colloidal crystal structure according to any one of claims 1 to 7, wherein the multiple types of two-dimensional crystals include two-dimensional crystals having four-fold symmetry when viewed from the thickness direction.

9. The items in question, An article with a colloidal crystal structure, characterized by comprising a colloidal crystal structure according to any one of claims 1 to 8 attached to the aforementioned target article.

10. The colloidal crystal structure is attached to the target article from the particle stationary layer side, as described in claim 9.

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