Articles with colloidal crystal structures

Abstract

The present invention provides an article with a colloidal crystal structure attached to it, which has a high individual identification function for the colloidal crystal structure and is difficult to see when attached to the article. [Solution] An article 101 with a colloidal crystal structure, comprising an article 110 and a colloidal crystal structure 1 attached to the article 110, wherein the colloidal crystal structure 1 has a particle immobilization layer 20 and a plurality of colloidal particles 30 provided inside the particle immobilization layer 20, and the plurality of colloidal particles 30 are embedded in the particle immobilization layer 20 and arranged apart from each other along a plane direction perpendicular to the thickness direction of the particle immobilization 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 directions of the plurality of types of two-dimensional crystals are different from each other, and the colloidal particles 30 are provided on the surface of the article 110.

Description

Technical Field

[0001] The present invention relates to 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 consisting 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] On the other hand, when attaching a colloidal crystal structure to an article for individual identification of that article, the inventors are considering how to ensure that the colloidal crystal structure does not impair the appearance (design) of the article. In this regard, the inventors believe it is important to make the colloidal crystal structure difficult to see when attached to the article.

[0008] In contrast, when the immobilized two-dimensional colloidal crystal described in Patent Document 1 is attached to an article in the form in which the colloidal crystal is immobilized on a substrate by resin, as shown in Figure 1 of Patent Document 1, the immobilized two-dimensional colloidal crystal is usually attached to the article from the substrate side via an adhesive member. In this case, the area where the immobilized two-dimensional colloidal crystal is attached to the article tends to become thicker due to the influence of the substrate, adhesive member, etc., which may make the immobilized two-dimensional colloidal crystal more easily visible when attached to the article.

[0009] Based on the above, it can be said that there is room for improvement in the immobilized two-dimensional colloidal crystal described in Patent Document 1, in terms of enhancing the individual identification function and making it less visible when attached to the target article.

[0010] The present invention has been made to solve the above problems, and aims to provide an article with a colloidal crystal structure attached to it, which has a high individual identification function of the colloidal crystal structure, and which is difficult to see when the colloidal crystal structure is attached to the article. [Means for solving the problem]

[0011] The present invention provides an article with a colloidal crystal structure, comprising: an article to be addressed; and a colloidal crystal structure attached to the article to be addressed, wherein the colloidal crystal structure has a particle-fixed layer and a plurality of colloidal particles provided inside the particle-fixed layer, and the plurality of colloidal particles are embedded in the particle-fixed layer and arranged apart from each other along a plane direction perpendicular to the thickness direction of the particle-fixed 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 colloidal particles are provided on the surface of the article to be addressed. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an article with a colloidal crystal structure attached to it, which has a high individual identification function of the colloidal crystal structure, and which is difficult to see when the colloidal crystal structure is attached to the article. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic plan view showing an example of an article with 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 an article with a colloidal crystal structure as 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 of an article with a colloidal crystal structure as 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 an article with a colloidal crystal structure, as 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 an article with a colloidal crystal structure as 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 an article with a colloidal crystal structure, as shown in Figure 1. [Figure 7] Figure 7 is a schematic, enlarged plan view showing an example of an article with a colloidal crystal structure according to Embodiment 2 of the present invention. [Figure 8] Figure 8 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 of an article with a colloidal crystal structure as shown in Figure 7. [Figure 9] Figure 9 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. [Figure 10] Figure 10 is a schematic cross-sectional view showing an example of an article with a colloidal crystal structure according to Embodiment 4 of the present invention. [Figure 11]FIG. 11 is a cross-sectional view schematically showing an example of an article with a colloidal crystal structure according to Embodiment 5 of the present invention. [Embodiments for Carrying Out the Invention]

[0014] Hereinafter, the article with a 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, a combination of a plurality of the individual preferred configurations described below is also within the scope of the present invention.

[0015] 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 a strictly literal aspect, but also mean a substantially equivalent range, for example, a range including a difference of about several percent.

[0016] [Article with Colloidal Crystal Structure] The article with a colloidal crystal structure of the present invention includes a target article and a colloidal crystal structure attached to the target article. The colloidal crystal structure has a particle fixing layer 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 while being separated from each other along a plane direction perpendicular to the thickness direction of the particle fixing layer, and constitute 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 colloidal particles are provided on the surface of the target article.

[0017] In the article with a colloidal crystal structure of the present invention, in the colloidal crystal structure, a plurality of colloidal particles are buried in the particle fixing layer and are arranged while being separated from each other along a plane direction perpendicular to the thickness direction of the particle fixing layer, and constitute a plurality of types of two-dimensional crystals. As a result, when light is irradiated on the colloidal crystal structure in the article with a colloidal crystal structure of the present invention, a diffraction pattern derived from the plurality of types of two-dimensional crystals formed by the colloidal particles appears.

[0018] Furthermore, in the article with the colloidal crystal structure of the present invention, in the colloidal crystal structure, when viewed from the thickness direction, the directions of the symmetry axes along the plane directions of the plurality of types of two-dimensional crystals are different from each other. From this, in the article with the colloidal crystal structure of the present invention, the diffraction pattern of the colloidal crystal structure includes not only the symmetry of the two-dimensional crystal but also the direction of the symmetry axis of the two-dimensional crystal as a parameter. Moreover, in the article with the colloidal crystal structure of the present invention, in the colloidal crystal structure, the directions of the symmetry axes of the plurality of types of two-dimensional crystals are different from each other. Therefore, in the article with the colloidal crystal structure of the present invention, the diffraction pattern of the colloidal crystal structure can be indexed not only by the combination of the symmetry and the direction of the symmetry axis in each two-dimensional crystal but also by the combination of the directions of the symmetry axes in the plurality of types of two-dimensional crystals, and the uniqueness is enhanced. From this, in the article with the colloidal crystal structure of the present invention, the individual identification function of the colloidal crystal structure is enhanced.

[0019] For example, when there are a plurality of articles with the colloidal crystal structure including the article with the colloidal crystal structure of the present invention, the diffraction pattern of the colloidal crystal structure in the article with the colloidal crystal structure of the present invention can be easily used as an index for individual identification to identify the article with the colloidal crystal structure of the present invention from the plurality of articles with the colloidal crystal structure. Therefore, by detecting and confirming the diffraction pattern of the colloidal crystal structure in the article with the colloidal crystal structure of the present invention, it becomes easier to identify the target article in the article with the colloidal crystal structure of the present invention.

[0020] Furthermore, in the article with the colloidal crystal structure of the present invention, in the state where the colloidal crystal structure is attached to the target article, the colloidal particles are provided on the surface of the target article. Here, the mode of "the colloidal particles are provided on the surface of the target article" includes the mode of "the colloidal particles are directly provided on the surface of the target article" and the mode of "the colloidal particles are provided on the surface of the target article through a layer with a thickness of 100 nm or less".

[0021] In the colloidal crystal structure-equipped article of the present invention, since the colloidal particles are provided on the surface of the target article in the above-described manner, it becomes possible to attach the colloidal particles, and by extension the colloidal crystal structure, to the target article without the need for relatively thick components such as a substrate or adhesive member. Therefore, in the colloidal crystal structure-equipped article of the present invention, the area where the colloidal crystal structure is attached to the target article does not become thick (it can be made thinner), so the colloidal crystal structure becomes less visible when attached to the target article. When the colloidal crystal structure becomes less visible when attached to the target article, the appearance (design) of the target article is less likely to be impaired by the colloidal crystal structure.

[0022] Based on the above, the article with a colloidal crystal structure of the present invention has a configuration in which the colloidal crystal structure is attached to the target article, and the colloidal crystal structure has a high individual identification function, making it possible to realize an article with a colloidal crystal structure that is difficult to see when attached to the target article.

[0023] Furthermore, in the article with the colloidal crystal structure of the present invention, the colloidal particles, and consequently the colloidal crystal structure, are attached to the article without the need for a substrate, adhesive member, or other relatively thick material. Therefore, compared to the case where the colloidal particles, and consequently the colloidal crystal structure, are attached to the article via a substrate, adhesive member, or other relatively thick material, when light is irradiated onto the colloidal crystal structure, the diffracted light generated by diffraction by the colloidal particles is suppressed from being absorbed, scattered, or refracted by the substrate, adhesive member, or other relatively thick material. As a result, in the article with the colloidal crystal structure of the present invention, the intensity of the diffraction pattern of the colloidal crystal structure increases (it becomes brighter), and the shape of the diffraction pattern improves (it becomes clearer). Consequently, in the article with the colloidal crystal structure of the present invention, the diffraction pattern of the colloidal crystal structure becomes easier to detect.

[0024] The following describes embodiments of the article with a colloidal crystal structure according to the present invention.

[0025] 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.

[0026] The drawings shown below are schematic representations, and their dimensions, aspect ratios, and scales may differ from those of the actual product.

[0027] <Embodiment 1> In the colloidal crystal structure article 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.

[0028] Figure 1 is a schematic plan view showing an example of an article with 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 article with 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 of the article with the colloidal crystal structure shown in Figures 1 and 2.

[0029] The colloidal crystal structure article 101 shown in Figures 1 and 2 comprises the target article 110 and the colloidal crystal structure 1.

[0030] The colloidal crystal structure 1 is attached to the object 110.

[0031] The colloidal crystal structure 1 has a particle immobilization layer 20 and a plurality of colloidal particles 30.

[0032] 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 opposite to the target article 110. The second surface 20b of the particle-fixing layer 20 is the surface of the particle-fixing layer 20 on the side facing the target article 110.

[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] 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 two-dimensionally, not three-dimensionally. Because the multiple colloidal particles 30 are arranged two-dimensionally, they are less visible compared to when they are arranged three-dimensionally.

[0039] To be visible means that it can be visually confirmed in the visible light spectrum.

[0040] The visible light region refers to the wavelength range between 360 nm and 830 nm.

[0041] 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.

[0042] The two-dimensional crystals R1a, R1b, R1c, R1d, and R1e each possess a six-fold symmetry when viewed from the thickness direction.

[0043] The rotational symmetry of a two-dimensional crystal when viewed from the thickness direction can be confirmed by the diffraction pattern described later.

[0044] As described above, in the colloidal crystal structure article 101, 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 in the colloidal crystal structure article 101, 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.

[0045] Furthermore, in the article 101 with a colloidal crystal structure, 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, the 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.

[0046] 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.

[0047] From the above, in article 101 with a colloidal crystal structure, the diffraction pattern of the 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 article 101 with a colloidal crystal structure, the symmetry axes of the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e in the colloidal crystal structure 1 are different from each other. Therefore, in the article 101 with a colloidal crystal structure, the diffraction pattern of the 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 the colloidal crystal structure 1 is enhanced in the article 101 with a colloidal crystal structure.

[0048] For example, if there are multiple articles with colloidal crystal structures, including article 101 with a colloidal crystal structure, the diffraction pattern of the colloidal crystal structure 1 in article 101 can be easily used as an indicator for individual identification to distinguish article 101 from the other articles with colloidal crystal structures. Therefore, by detecting and confirming the diffraction pattern of the colloidal crystal structure 1 in article 101 with a colloidal crystal structure, it becomes easier to identify the target article 110 in article 101 with a colloidal crystal structure.

[0049] Furthermore, in the article 101 with the colloidal crystal structure, the colloidal particles 30 are provided on the surface of the article 110 while the colloidal crystal structure 1 is attached to the article 110. Here, the description "the colloidal particles 30 are provided on the surface of the article 110" includes both the description "the colloidal particles 30 are directly provided on the surface of the article 110" and the description "the colloidal particles 30 are provided on the surface of the article 110 via a layer with a thickness of 100 nm or less."

[0050] In the colloidal crystal structure-attached article 101, the colloidal particles 30 are provided on the surface of the target article 110 in the above-described manner, making it possible to attach the colloidal particles 30, and by extension the colloidal crystal structure 1, to the target article 110 without the need for relatively thick components such as a substrate or adhesive member. Therefore, in the colloidal crystal structure-attached article 101, the area where the colloidal crystal structure 1 is attached to the target article 110 does not become thick (it can be made thinner), making the colloidal crystal structure 1 less visible when attached to the target article 110. When the colloidal crystal structure 1 is less visible when attached to the target article 110, the appearance (design) of the target article 110 is less likely to be impaired by the colloidal crystal structure 1.

[0051] Based on the above, the colloidal crystal structure article 101 has a configuration in which the colloidal crystal structure 1 is attached to the target article 110, and the colloidal crystal structure 1 has a high individual identification function, making it possible to realize a colloidal crystal structure article in which the colloidal crystal structure 1 is difficult to see when attached to the target article 110.

[0052] Furthermore, in the colloidal crystal structure-attached article 101, the colloidal particles 30, and consequently the colloidal crystal structure 1, are attached to the target article 110 without the use of relatively thick materials such as a substrate or adhesive material. Therefore, compared to the case where the colloidal particles 30, and consequently the colloidal crystal structure 1, are attached to the target article 110 via relatively thick materials such as a substrate or adhesive material, when light is irradiated onto the colloidal crystal structure 1, the diffracted light generated by diffraction by the colloidal particles 30 is suppressed from being absorbed, scattered, or refracted by relatively thick materials such as a substrate or adhesive material. As a result, in the colloidal crystal structure-attached article 101, the intensity of the diffraction pattern of the colloidal crystal structure 1 increases (it becomes brighter), and the shape of the diffraction pattern improves (it becomes clearer). For example, a bright and clear 6-fold symmetric diffraction pattern appears, as shown in Figure 3. As a result, the diffraction pattern of the colloidal crystal structure 1 is easier to detect in the colloidal crystal structure-attached article 101.

[0053] If the colloidal crystal structure 1 and the target article 110 are transparent, for example, if the light transmittance in the visible light region of each component of the colloidal crystal structure 1 and the target article 110 is 80% or more, then when detecting the diffraction pattern of the colloidal crystal structure 1, the article 101 with the colloidal crystal structure may be irradiated with light from the colloidal crystal structure 1 side or from the target article 110 side.

[0054] The two-dimensional crystals R1a, R1b, R1c, R1d, and R1e, which constitute the colloidal particles 30, are each unique and irreproducible. Therefore, the diffraction patterns derived from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e are also each unique and irreproducible. This will be explained below with an example of a manufacturing method for the article 101 with the colloidal crystal structure.

[0055] First, a colloidal dispersion is prepared in which multiple colloidal particles 30 are dispersed in a dispersion medium.

[0056] 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.

[0057] Next, the colloidal dispersion is applied to one main surface of the target article 110.

[0058] 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 target article 110, or the target article 110 may be immersed in the colloidal dispersion.

[0059] Next, the dispersion medium in the colloidal dispersion applied to one main surface of the target article 110 is dried, leaving multiple colloidal particles 30 on that main surface of the target article 110. Then, of the remaining multiple colloidal particles 30, all but the layer closest to the target article 110 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 target article 110, separating from each other by electrostatic repulsion.

[0060] Finally, a particle-fixing layer 20 is formed on one main surface of the target article 110 so that multiple colloidal particles 30 arranged in two dimensions are embedded.

[0061] The method for forming the particle immobilization layer 20 is not particularly limited.

[0062] As a result, the colloidal crystal structure 1 is formed on one main surface of the target article 110. In other words, an article 101 with a colloidal crystal structure is manufactured, having a configuration in which the colloidal crystal structure 1 is attached to the target article 110.

[0063] Furthermore, the colloidal crystal structure article 101 may be manufactured by the following method. First, in the method described above, the object to which the colloidal dispersion containing a plurality of colloidal particles 30 is applied and the object to which the particle immobilization layer 20 is formed are made to one main surface of the same substrate other than the target article 110, thereby creating a structure in which the colloidal crystal structure 1 is formed on one main surface of the substrate. Then, the above structure is attached to the target article 110 from the colloidal crystal structure 1 side. After that, the substrate is removed from the above structure by methods such as peeling and polishing, thereby manufacturing the colloidal crystal structure article 101 having a configuration in which the colloidal crystal structure 1 is attached to the target article 110.

[0064] In the colloidal crystal structure article 101 manufactured by the above method, in the colloidal crystal structure 1, a plurality of 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 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 plurality of colloidal particles 30, each 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, and in this case the target article 110 to which the colloidal crystal structure 1 is attached is a genuine article, then, for example, the authenticity of the article to be determined can be determined by following the procedure below.

[0068] First, when light is shone on the item to be judged, it is checked 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 checked 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, target item 110, 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, target item 110. In this case, if information is prepared in advance regarding the diffraction patterns originating from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e present in the colloidal crystal structure 1, such as their shape, size, position, the direction (angle) of the axis of symmetry along the plane, and what kind of diffraction pattern appears when light is irradiated at a given angle, then the authenticity of the item can be determined more efficiently by checking the diffraction pattern detected from the item based on this information.

[0069] When the colloidal crystal structure 1 is used for the security purposes described above, it is envisioned to be attached to relatively expensive items such as paintings, watches, eyewear, jewelry, and perfumes, which are designated as target items 110. 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 the colloidal crystal structure 1 are unique and irreproducible, and the diffraction patterns derived from the two-dimensional crystals R1a, R1b, R1c, R1d, and R1e are also unique and irreproducible. Therefore, a third party cannot counterfeit the colloidal crystal structure 1. Thus, the 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] Furthermore, as mentioned above, in the colloidal crystal structure 1, multiple colloidal particles 30 are arranged two-dimensionally, making them less visible compared to when they are arranged three-dimensionally. Therefore, especially when the particle fixing layer 20 is transparent, as will be described later, the entire colloidal crystal structure 1 becomes difficult to see. When the colloidal crystal structure 1 is difficult to see, a third party attempting to counterfeit the genuine article 110 will have difficulty noticing the presence of the colloidal crystal structure 1 attached to the article 110. Therefore, a third party will not attempt to manufacture a counterfeit product that includes the colloidal crystal structure 1, and thus a complete counterfeit product including the colloidal crystal structure 1 will not be manufactured. In this respect as well, the colloidal crystal structure 1 exhibits a high level of anti-counterfeiting effect.

[0072] The following describes each component of the colloidal crystal structure article 101.

[0073] 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.

[0074] Each component of the colloidal crystal structure 1 is described below.

[0075] (particle fixed layer) At least the particle immobilization layer 20 of the particle immobilization layer 20 and colloidal particles 30 may be in contact with the target article 110. In this case, the particle immobilization layer 20 may be in contact with the entire main surface of one of the target article 110, or with a part of the main surface of one of the target article 110.

[0076] The particle immobilization layer 20 is preferably transparent. For example, the particle immobilization layer 20 is preferably 80% or more in light transmittance in the visible light region. In this case, the particle immobilization layer 20 becomes difficult to see, and consequently, the colloidal crystal structure 1 becomes difficult to see, thereby increasing the anti-counterfeiting effect when the colloidal crystal structure 1 is used for security purposes, as described above.

[0077] The number-average molecular weight of the constituent material of the particle immobilization layer 20 is preferably 1000 or more. In this case, the colloidal particles 30 are more easily immobilized in the particle immobilization layer 20, so that even if an external force is applied to the colloidal crystal structure 1, for example, 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.

[0078] Preferably, the particle immobilization layer 20 has surface conformability that can follow the surface irregularities of the target article 110 to which it is attached. In this case, in the colloidal crystal structure-attached article 101 having a configuration in which the colloidal crystal structure 1 is attached to the target article 110, bubbles (air bubbles) are less likely to occur at the interface between the particle immobilization layer 20 and the target article 110. 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 target article 110. As a result, 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.

[0079] The particle immobilization layer 20 may have a single-layer structure or a multi-layer structure.

[0080] 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.

[0081] The resin layer is preferably composed of an ultraviolet-curable resin.

[0082] 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.

[0083] The particle immobilization layer 20 may include an adhesive layer that constitutes the second surface 20b, which is the surface of the particle immobilization layer 20 facing the target article 110. In this case, when attaching the colloidal crystal structure 1 to the target article 110 from the second surface 20b side of the particle immobilization layer 20, the adhesive action of the adhesive layer constituting the second surface 20b of the particle immobilization layer 20 makes it easier to firmly attach the colloidal crystal structure 1 to the target article 110.

[0084] The particle immobilization layer 20 may be composed entirely of an adhesive layer, or only partially of an adhesive layer.

[0085] The particle immobilization layer 20 may include, in addition to the adhesive layer, a layer other than the adhesive layer, such as a non-adhesive layer. In this case, the particle immobilization layer may include, in addition to the adhesive layer constituting the second surface 20b, a non-adhesive layer constituting the first surface 20a.

[0086] If the particle immobilization layer 20 includes an adhesive layer and a non-adhesive layer, the colloidal particles 30 may be provided across the interface between the adhesive layer and the non-adhesive layer, or they may not be provided across the interface between the adhesive layer and the non-adhesive layer, but may be embedded in the non-adhesive layer.

[0087] The non-adhesive layer may be, for example, the resin layer described above, which is preferably included in the particle immobilization layer 20.

[0088] The particle immobilization layer 20 may have a two-layer structure consisting of an adhesive layer and a non-adhesive layer, or it may have a structure consisting of three or more layers.

[0089] (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.

[0090] 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 object 110 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 object 110.

[0091] On the other hand, in the example shown in Figure 2, the particle immobilization layer 20 is also in contact with the target article 110, so both the particle immobilization layer 20 and the colloidal particles 30 are in contact with the target article 110.

[0092] 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.

[0093] 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.

[0094] When viewed from the thickness direction, the multiple colloidal particles 30 may be provided throughout the entire particle immobilization layer 20.

[0095] 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.

[0096] 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.

[0097] The average particle size of the multiple colloidal particles 30 is preferably 100 nm or more and 1000 nm or less. In this case, the colloidal particles 30 become less visible. Furthermore, when light is irradiated onto the colloidal crystal structure 1, both the intensity of the diffracted light diffracted by the colloidal particles 30 and the intensity of the scattered light scattered by the colloidal particles 30 become low, making the structural color derived from the colloidal particles 30 less visible. As a result, the anti-counterfeiting effect when the colloidal crystal structure 1 is used for security purposes, as described above, is enhanced.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] The colloidal particles 30 may be inorganic particles or organic particles.

[0102] 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.

[0103] 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.

[0104] The following describes the relationship between the refractive indices of each component of the colloidal crystal structure 1.

[0105] In the visible light region, the refractive indices of the particle-fixed layer 20 and the colloidal particles 30 may be the same. In this case, the colloidal crystal structure 1 becomes less visible, thus enhancing the anti-counterfeiting effect when the colloidal crystal structure 1 is used for security purposes, as described above.

[0106] In the visible light region, the refractive indices of the particle stationary layer 20 and the colloidal particles 30 may be different from each other.

[0107] In the visible light region, the refractive index of the colloidal particles 30 is preferably such that the difference between it and the refractive index of the particle-fixed layer 20 is 0.001 or more and 0.15 or less. In this case, the colloidal particles 30 become difficult to see. Furthermore, when light is shone on the colloidal crystal structure 1, both the intensity of the diffracted light diffracted by the colloidal particles 30 and the intensity of the scattered light scattered by the colloidal particles 30 are low, making it difficult to see the structural color originating from the colloidal particles 30. As a result, the anti-counterfeiting effect when the colloidal crystal structure 1 is used for security purposes, as described above, is enhanced.

[0108] In the visible light region, the refractive index of the colloidal particles 30 may be less than 0.001 or greater than 0.15 compared to the refractive index of the particle-fixed layer 20.

[0109] 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.

[0110] 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.

[0111] The refractive index of the colloidal particles 30 in the visible light region is preferably 1.3 or higher and 2.3 or lower.

[0112] The refractive indices of the particle stationary layer 20 and the colloidal particles 30 in the visible light region are measured by the V-block method.

[0113] In the infrared region, the refractive indices of the particle stationary layer 20 and the colloidal particles 30 may be the same.

[0114] In the infrared region, the refractive indices of the particle stationary layer 20 and the colloidal particles 30 may be different from each other. In this case, the colloidal crystal structure 1 becomes detectable in the infrared region.

[0115] The infrared region refers to the wavelength range from 830 nm upwards to 1 mm downwards.

[0116] The refractive index of the particle immobilization layer 20 in the infrared region is preferably 0.4 or higher and 5.7 or lower.

[0117] 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.

[0118] The refractive index of the colloidal particles 30 in the infrared region is preferably 0.4 or higher and 5.7 or lower.

[0119] The refractive indices of the particle-fixed layer 20 and the colloidal particles 30 in the infrared region are measured by the V-block method.

[0120] In colloidal crystal structure 1, for example, if the refractive indices of the particle fixed layer 20 and the colloidal particles 30 are the same in the visible light region, and the refractive indices of the particle fixed layer 20 and the colloidal particles 30 are different in the infrared light region, then colloidal crystal structure 1 becomes undetectable (invisible) in the visible light region, but detectable in the infrared light region. In this case, a third party attempting to manufacture counterfeit goods would not only be unable to notice the existence of colloidal crystal structure 1, but even if they did notice its existence, they would be unable to counterfeit colloidal crystal structure 1 in which there are unique and irreproducible 2D crystals R1a, R1b, R1c, R1d, and R1e, and in which the refractive indices of the particle fixed layer 20 and the colloidal particles 30 are different in the infrared light region.

[0121] If the colloidal crystal structure 1 is detectable in the infrared region, then, for example, if the colloidal crystal structure 1 is attached to the back of a painting or the back of a watch dial, the colloidal crystal structure 1 will not be visible from the front of the painting, watch, etc., but will be detectable in the infrared region.

[0122] The colloidal crystal structure 1 may or may not have additional components other than the particle fixing layer 20 and the multiple colloidal particles 30, provided that the area where the colloidal crystal structure 1 is attached to the target article 110 does not become thick and the state in which the colloidal crystal structure 1 is not easily visible is maintained.

[0123] (Middle class) Figure 4 is a schematic cross-sectional view showing a second example of a cross-section along the thickness direction of an article with a colloidal crystal structure, as shown in Figure 1.

[0124] As shown in Figure 4, the colloidal crystal structure 1 may further have an intermediate layer 40 with a thickness of 100 nm or less that is in contact with the target article 110 and the colloidal particles 30 between the target article 110 and the colloidal particles 30.

[0125] Because the intermediate layer 40 is in contact with the colloidal particles 30, the colloidal particles 30 are protected not only by the target article 110 and the particle-fixing layer 20, but also by the intermediate layer 40.

[0126] Because the intermediate layer 40 is in contact with the target article 110 and the colloidal particles 30, the colloidal particles 30 are fixed to the target article 110 via the intermediate layer 40. When the colloidal particles 30 are fixed to the target article 110, 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.

[0127] One way to obtain a configuration in which the intermediate layer 40 is in contact with the target article 110 and the colloidal particles 30 between the target article 110 and the colloidal particles 30 is, for example, when manufacturing an article 101 with a colloidal crystal structure using the method described above, to which the colloidal dispersion containing the colloidal particles 30 is applied is to use a target article 110 to which the intermediate layer 40 has been pre-provided on one main surface. When the colloidal dispersion is applied to one main surface of the target article 110 to which the intermediate layer 40 has been pre-provided, the colloidal particles 30 will be arranged two-dimensionally while adsorbed on the intermediate layer 40.

[0128] The thickness of the intermediate layer 40 is 100 nm or less, for example, between 1 nm and 100 nm.

[0129] The intermediate layer 40 is preferably composed of a metal oxide. In this case, titanium oxide is preferred as the metal oxide.

[0130] 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.

[0131] Figure 5 is a schematic cross-sectional view showing a third example of a cross-section along the thickness direction of an article with a colloidal crystal structure as shown in Figure 1.

[0132] As shown in Figure 5, the intermediate layer 40 may further extend in the planar direction between the target article 110 and the particle immobilization layer 20 so as to be in contact with both the target article 110 and the particle immobilization layer 20.

[0133] (Functional layer) Figure 6 is a schematic cross-sectional view showing a fourth example of a cross-section along the thickness direction of an article with a colloidal crystal structure, as shown in Figure 1.

[0134] As shown in Figure 6, the colloidal crystal structure 1 may further have a functional layer 50 provided on at least one of the following surfaces: the first surface 20a, which is the surface of the particle immobilization layer 20 opposite to the object 110, and the interface between the object 110 and the particle immobilization layer 20. In the example shown in Figure 6, the functional layer 50 is provided on the first surface 20a of the particle immobilization layer 20.

[0135] 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.

[0136] In addition, while Figure 6 illustrates the case where the functional layer 50 is provided in the configuration shown in Figure 2, the functional layer 50 may also be provided in configurations other than those shown in Figure 2, for example, in the configurations shown in either Figure 4 or Figure 5.

[0137] The colloidal crystal structure 1 may be provided with at least one of a notch (cutting notch) and an incision. For example, the particle immobilization layer 20 may be provided with at least one of a notch and an incision.

[0138] 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 more susceptible to damage when the colloidal crystal structure 1 is removed after being attached to the target article 110. 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 the genuine article and attach it to another article (for example, a counterfeit item).

[0139] <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.

[0140] Figure 7 is a schematic, enlarged plan view showing an example of an article with a colloidal crystal structure according to Embodiment 2 of the present invention. Figure 8 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 of the article with the colloidal crystal structure shown in Figure 7.

[0141] In the colloidal crystal structure 2 of the article 102 with a colloidal crystal structure shown in Figure 7, the multiple colloidal particles 30 constitute multiple types of two-dimensional crystals, including a two-dimensional crystal R2a that has four-fold symmetry when viewed from the thickness direction. Although not shown in Figure 7, 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.

[0142] 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 diffraction patterns originating from each two-dimensional crystal are bright and clear four-fold symmetric diffraction patterns, as shown in Figure 8.

[0143] 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.

[0144] 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 target article 110 when manufacturing the colloidal crystal structure 2 in the same manner as the colloidal crystal structure 1. For example, after applying the colloidal dispersion to one main surface of the target article 110, 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 other 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.

[0145] <Embodiment 3> In the colloidal crystal structure-equipped article of Embodiment 3 of the present invention, the colloidal crystal structure is attached to a portion of the surface of the article on the side of the colloidal crystal structure.

[0146] Figure 9 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.

[0147] In the colloidal crystal structure-equipped article 103 shown in Figure 9, the colloidal crystal structure 1 is attached to a portion of the surface (top surface in Figure 9) of the target article 110 on the side of the colloidal crystal structure 1.

[0148] In article 103 with a colloidal crystal structure, the colloidal crystal structure 1 is attached to a portion of the surface of article 110 on the side of the colloidal crystal structure 1 (the top surface in Figure 9). As a result, the area where the colloidal crystal structure 1 is attached to article 110 is convex compared to the area where the colloidal crystal structure 1 is not attached. Therefore, in article 103 with a colloidal crystal structure, a sharp step is created on the outer circumference of the colloidal crystal structure 1 between the surface of the colloidal crystal structure 1 opposite to article 110 (the first surface 20a of the particle immobilization layer 20 in Figure 9) and the surface of article 110 on the side of the colloidal crystal structure 1 (the top surface in Figure 9). Consequently, in article 103 with a colloidal crystal structure, this step becomes more noticeable, which may make the colloidal crystal structure 1 more visible.

[0149] In contrast, the following embodiments can be considered as configurations that make the colloidal crystal structure 1 even less visible.

[0150] <Embodiment 4> The colloidal crystal structure article of Embodiment 4 of the present invention further comprises a step-eliminating portion provided on the surface of the article facing the colloidal crystal structure, at a position on the outer periphery of the colloidal crystal structure. In the colloidal crystal structure article of Embodiment 4 of the present invention, the first thickness, which is the thickness of the end of the step-eliminating portion on the colloidal crystal structure side in the planar direction, is less than or equal to the thickness of the peripheral edge of the colloidal crystal structure. In the colloidal crystal structure article of Embodiment 4 of the present invention, the second thickness, which is the thickness of the end of the step-eliminating portion opposite to the colloidal crystal structure in the planar direction, is smaller than the first thickness of the step-eliminating portion.

[0151] Figure 10 is a schematic cross-sectional view showing an example of an article with a colloidal crystal structure according to Embodiment 4 of the present invention.

[0152] The colloidal crystal structure article 104 shown in Figure 10 further has a step-reducing portion 120 provided on the outer periphery of the colloidal crystal structure 1 on the surface of the target article 110 on the colloidal crystal structure 1 side (the top surface in Figure 10).

[0153] The step-reducing portion 120 only needs to be provided on at least a portion of the outer periphery of the colloidal crystal structure 1 on the surface of the target article 110 that is on the colloidal crystal structure 1 side. In other words, the step-reducing portion 120 may be provided on a portion of the outer periphery of the colloidal crystal structure 1 on the surface of the target article 110 that is on the colloidal crystal structure 1 side, or it may be provided on the entire outer periphery of the colloidal crystal structure 1.

[0154] The first thickness of the step-reducing portion 120, which is the thickness of the end on the colloidal crystal structure 1 side in the planar direction, is less than or equal to the thickness of the peripheral edge of the colloidal crystal structure 1. In the example shown in Figure 10, the first thickness of the step-reducing portion 120 is the same as the thickness of the peripheral edge of the colloidal crystal structure 1. However, the first thickness of the step-reducing portion 120 may be less than the thickness of the peripheral edge of the colloidal crystal structure 1.

[0155] The second thickness of the step-reducing section 120, which is the thickness of the end opposite to the colloidal crystal structure 1 in the planar direction, is smaller than the first thickness of the step-reducing section 120. In the example shown in Figure 10, the second thickness of the step-reducing section 120 is zero. Note that the second thickness of the step-reducing section 120 may be greater than zero, as long as it is smaller than the first thickness of the step-reducing section 120.

[0156] In the colloidal crystal structure article 104, the step-eliminating section 120 eliminates the step between the surface of the colloidal crystal structure 1 opposite to the target article 110 (the first surface 20a of the particle immobilization layer 20 in Figure 10) and the surface of the target article 110 on the colloidal crystal structure 1 side (the top surface in Figure 10). Specifically, when the colloidal crystal structure 1 and the step-eliminating section 120 are viewed as a single unit, the step located on the outer circumference does not change abruptly, but rather changes smoothly. As a result, in the colloidal crystal structure article 104, the step becomes less noticeable, making the colloidal crystal structure 1 less visible. In the colloidal crystal structure article 104, the colloidal crystal structure 1 is less visible, thus increasing the anti-counterfeiting effect when the colloidal crystal structure 1 is used for security purposes, as described above.

[0157] As shown in Figure 10, it is preferable that the step-reducing portion 120 has an inclined surface 120a that moves away from the colloidal crystal structure 1 in the planar direction as it approaches the target article 110 in the thickness direction. In other words, it is preferable that the step-reducing portion 120 has an inclined surface 120a whose height position decreases as it moves away from the colloidal crystal structure 1 in the planar direction. In this case, as the thickness of the step-reducing portion 120 decreases as it moves away from the colloidal crystal structure 1 in the planar direction, the step located on its outer circumference becomes even smoother when the colloidal crystal structure 1 and the step-reducing portion 120 are viewed as a single unit. As a result, in the article 104 with the colloidal crystal structure, the step becomes even less noticeable, making the colloidal crystal structure 1 even less visible, and thus further enhancing the anti-counterfeiting effect when the colloidal crystal structure 1 is used for security purposes, as described above.

[0158] Although this is a different form from Embodiment 4, in order to obtain the same effect as Embodiment 4, the colloidal crystal structure 1 may be machined from the article 103 with the colloidal crystal structure shown in Figure 9 so that the surface of the colloidal crystal structure 1 (the first surface 20a of the particle immobilization layer 20 in Figure 9) changes smoothly from the inside to the outside (outer circumference) in the planar direction. For example, the colloidal crystal structure 1 may be machined from the article 103 with the colloidal crystal structure shown in Figure 9 so that it has an inclined surface in which the height position decreases from the inside to the outside (outer circumference) in the planar direction.

[0159] <Embodiment 5> In the article with a colloidal crystal structure according to Embodiment 5 of the present invention, the periphery of the colloidal crystal structure is aligned with the periphery of the article.

[0160] Figure 11 is a schematic cross-sectional view showing an example of an article with a colloidal crystal structure according to Embodiment 5 of the present invention.

[0161] In the colloidal crystal structure article 105 shown in Figure 11, the periphery of the colloidal crystal structure 1 follows the periphery of the target article 110. As a result, in the colloidal crystal structure article 105, a step is less likely to occur between the surface of the colloidal crystal structure 1 opposite to the target article 110 (the first surface 20a of the particle immobilization layer 20 in Figure 11) and the surface of the target article 110 on the side of the colloidal crystal structure 1 (the top surface in Figure 11). Consequently, the colloidal crystal structure 1 becomes less visible in the colloidal crystal structure article 105. Because the colloidal crystal structure 1 is less visible in the colloidal crystal structure article 105, the anti-counterfeiting effect when the colloidal crystal structure 1 is used for security purposes, as described above, is more likely to be enhanced.

[0162] In article 105 with a colloidal crystal structure, the periphery of the colloidal crystal structure 1 does not need to strictly follow (overlap) the periphery of the target article 110, but only needs to substantially follow the periphery of the target article 110. For example, the periphery of the colloidal crystal structure 1 may be located inside the periphery of the target article 110, or it may be located outside the periphery of the target article 110.

[0163] In the article 105 with a colloidal crystal structure, the multiple colloidal particles 30 may be provided in a part of the particle-fixed layer 20 in the planar direction, as shown in Figure 11, or they may be provided throughout the entire particle-fixed layer 20.

[0164] In addition, while Figures 9 to 11 illustrate the case where the colloidal crystal structure 1 shown in Figure 1 is attached to the target article 110, the same applies when a colloidal crystal structure other than the colloidal crystal structure 1 shown in Figure 1, for example, the colloidal crystal structure 2 shown in Figure 7, is attached to the target article 110.

[0165] 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.

[0166] In the colloidal crystal structure article 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 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). In the colloidal crystal structure article of the present invention, the multiple types of two-dimensional crystals present in the colloidal crystal structure 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, in the colloidal crystal structure article of the present invention, the multiple types of two-dimensional crystals present in the colloidal crystal structure 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.

[0167] In the article with the colloidal crystal structure of the present invention, the number of types of two-dimensional crystals present in the colloidal crystal structure is not limited to the five types shown in Embodiment 1, but may be multiple types other than the five types.

[0168] In the article with the colloidal crystal structure of the present invention, the form of the colloidal crystal structure is not particularly limited and may be, for example, a tag, film, card, seal, etc. [Explanation of symbols]

[0169] 1, 2 Colloidal crystal structures 20 Particle fixed layer 20a First surface of the particle immobilization layer 20b Second surface of the particle immobilization layer 30 colloidal particles 40 Middle Class 50 Functional Layers 101, 102, 103, 104, 105 Articles with colloidal crystal structures 110 Target items 120 Step-leveling section 120a Inclined Surface R1a, R1b, R1c, R1d, R1e, R2a 2D Crystals X1a, X1b, X1c, X1d, X1e symmetrical axes

Claims

1. The items in question, The object comprises a colloidal crystal structure attached to the aforementioned object, The colloidal crystal structure comprises a particle-fixed layer and a plurality of colloidal particles provided inside the particle-fixed 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. An article with a colloidal crystal structure, characterized in that the colloidal particles are provided on the surface of the target article.

2. The colloidal crystal structure article according to claim 1, wherein at least the particle immobilization layer among the particle immobilization layer and the colloidal particles is in contact with the target article.

3. The colloidal crystal structure article according to claim 2, wherein both the particle immobilization layer and the colloidal particles are in contact with the target article.

4. The colloidal crystal structure article according to claim 1, further comprising an intermediate layer having a thickness of 100 nm or less that is in contact with the target article and the colloidal particles between the target article and the colloidal particles.

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

6. An article with a colloidal crystal structure according to any one of claims 1 to 5, wherein the multiple types of two-dimensional crystals include two-dimensional crystals having six-fold symmetry when viewed from the thickness direction.

7. An article with a 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 four-fold symmetry when viewed from the thickness direction.

8. The object further comprises a step-eliminating portion provided on the outer periphery of the colloidal crystal structure on the surface of the colloidal crystal structure, The first thickness, which is the thickness of the end portion on the colloidal crystal structure side in the surface direction of the step-eliminating portion, is less than or equal to the thickness of the peripheral edge of the colloidal crystal structure. The article with a colloidal crystal structure according to any one of claims 1 to 7, wherein the second thickness, which is the thickness of the end of the step-reducing portion opposite to the colloidal crystal structure in the surface direction, is smaller than the first thickness of the step-reducing portion.

9. The colloidal crystal structure article according to claim 8, wherein the step-reducing portion has an inclined surface that moves away from the colloidal crystal structure in the surface direction as it approaches the target article in the thickness direction.

10. The colloidal crystal structure article according to any one of claims 1 to 7, wherein the periphery of the colloidal crystal structure is along the periphery of the target article.

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