Color-developing sheet, color-developing article, transfer foil, and method for producing transfer foil

Abstract

To provide a color developing sheet capable of preventing a multilayer film layer from being damaged by a tension.SOLUTION: A color developing sheet includes a support medium 11 and a multilayer film layer 13 formed on the support medium 11. The multilayer film layer 13 is configured such that layers 13a, 13b neighboring to each other in the multilayer film layer 13 have refractive indexes different from each other and that a light reflectance ratio at a specific wavelength region in incident light to the multilayer film layer 13 is higher than a light reflectance ratio at another wavelength region. Furthermore, the support medium 11 at least includes a pressure resistance layer 11a and a cushion layer 11b, being two layers having hardness different from each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a color-developing sheet, a color-developing article, a transfer foil, and a method for producing the transfer foil. [Background technology]

[0002] Structural colors, which are often observed in natural creatures such as Morpho butterflies, are colors that are visible due to optical phenomena caused by the fine structure of an object, such as light diffraction, interference, and scattering. For example, structural colors caused by multilayer interference occur when light is reflected at the interface between adjacent thin films and the reflected light interferes with each other. Multilayer interference is one of the principles behind the coloring of Morpho butterfly wings. In Morpho butterfly wings, in addition to multilayer interference, light is scattered and diffracted due to the fine unevenness of the wing surface, resulting in a vivid blue color that can be seen from a wide observation angle.

[0003] As a coloring sheet that artificially reproduces structural colors like those of the wings of a Morpho butterfly, a coloring sheet in which a multilayer film layer is laminated on a layer having fine unevenness arranged unevenly, as described in Patent Document 1, has been proposed. In a coloring sheet in which a multilayer film layer is laminated on a flat surface, the wavelength of reflected light seen changes greatly depending on the observation angle, so the color seen on the coloring sheet changes greatly depending on the observation angle. In contrast, in the coloring sheet described in Patent Document 1, the reflected light intensified by interference spreads in multiple directions due to the irregular unevenness, so the color change depending on the observation angle is gradual. As a result, a specific color is observed at a wide observation angle like the wings of a Morpho butterfly. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-112732 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, an inorganic compound is used in the multilayer film layer of the color-developing sheet described in Patent Document 1. In general, inorganic compounds are brittle and easily cause defects such as cracks and chips due to external stimuli. Therefore, in the transfer foil formed by forming an adhesive layer on the color-developing sheet described in Patent Document 1, for example, when a user pulls the transfer foil so that the transfer foil peels off from the adherend in order to re-apply the transfer foil after the transfer foil is attached to the adherend, tensile stress is applied to the transfer foil, and the multilayer film layer is deformed, cracks, chips, etc. may occur in the multilayer film layer, and the color-developing sheet may have a defective appearance.

[0006] An object of the present invention is to provide a color-developing sheet, a color-developing article, a transfer foil, and a method for producing a transfer foil, which are capable of suppressing damage to a multilayer film layer due to pulling. [Means for solving the problem]

[0007] In order to solve the above problems, a color-developing sheet according to one aspect of the present invention comprises: (a) a support; and a multilayer film layer formed on the support. a resin layer disposed between the support and the multilayer film layer; (b) the multilayer film layer is configured such that adjacent layers in the multilayer film layer have mutually different refractive indices, and the reflectance of light in a specific wavelength range among light incident on the multilayer film layer is higher than the reflectance of light in other wavelength ranges; (c) the surface of the multilayer film layer facing the support has a first uneven structure having a plurality of recesses; (d) when viewed in a direction along the thickness direction of the multilayer film layer, the pattern configured by the recesses includes a pattern consisting of a set of a plurality of graphic elements, each of which has a length along the first direction that is equal to or less than a sub-wavelength and a length along a second direction perpendicular to the first direction that is equal to or greater than the length along the first direction; (e) in the plurality of graphic elements, the standard deviation of the length along the second direction is larger than the standard deviation of the length along the first direction; and (f) the support includes at least two layers having hardnesses different from each other. (g) of the two layers having different hardnesses, the layer having the higher hardness is disposed closer to the multilayer film layer than the layer having the lower hardness and is in contact with the resin layer, and the layer having the lower hardness constitutes the outermost surface; (h) the layer having the higher hardness has a thickness within the range of 10 μm to 100 μm, and the layer having the lower hardness has a thickness greater than the layer having the higher hardness and within the range of 50 μm to 300 μm. The gist of the present invention is as follows.

[0008] A color-developing article according to one aspect of the present invention includes the above-mentioned color-developing sheet and an adherend to which the color-developing sheet is attached.

[0009] A transfer foil according to one embodiment of the present invention includes: (a) a support; a concave-convex structure layer formed on the support and having a concave-convex structure on a surface opposite to the support; a multilayer film layer formed on the concave-convex structure layer and having a surface shape following the concave-convex structure; an anchor layer formed on the multilayer film layer; a light absorbing layer formed on the anchor layer; and an adhesive layer formed on the light absorbing layer; (b) the multilayer film layer is configured such that adjacent layers in the multilayer film layer have mutually different refractive indices, and the reflectance of light in a specific wavelength range of light incident on the multilayer film layer is higher than the reflectance of light in other wavelength ranges; (c) the convex portions constituting the concave-convex structure, as viewed from the multilayer film layer side, include a pattern constituted by the convex portions, the pattern being made up of a set of a plurality of graphic elements each having a length along a first direction that is equal to or less than a sub-wavelength and a length along a second direction perpendicular to the first direction that is equal to or greater than the length along the first direction, and the standard deviation of the lengths along the second direction in the plurality of graphic elements is greater than the standard deviation of the lengths along the first direction; and (d) the support includes at least two layers each having a hardness different from each other. (e) of the two layers having different hardnesses, the layer having a higher hardness is disposed closer to the multilayer film layer than the layer having a lower hardness and is in contact with the uneven structure layer, and the layer having a lower hardness constitutes the outermost surface; (f) the layer having a higher hardness has a thickness within a range of 10 μm or more and 100 μm or less, and the layer having a lower hardness has a thickness within a range of 50 to 300 μm that is thicker than the layer having a higher hardness. The gist of the present invention is as follows.

[0010] A method for producing a transfer foil according to one embodiment of the present invention includes the steps of: (a) forming a resin layer having a concave-convex structure on one surface of a support; (b) forming a multilayer film layer along the concave-convex structure such that adjacent layers in the multilayer film layer have different refractive indices and the reflectance of light in a specific wavelength range of light incident on the multilayer film layer is higher than the reflectance of light in other wavelength ranges; (c) forming an anchor layer on the surface of the multilayer film layer opposite the resin layer side; (d) forming a light absorbing layer on the surface of the anchor layer opposite the multilayer film layer; and (e) forming an anchor layer on the surface of the light absorbing layer opposite the anchor layer. and forming an adhesive layer on the support, (f) in the step of forming the resin layer, a pattern consisting of one or more steps of convex portions constituting the concave-convex structure includes a pattern consisting of a set of multiple geometric elements, each having a length along a first direction that is equal to or less than a sub-wavelength and a length along a second direction perpendicular to the first direction that is equal to or greater than the length along the first direction, when viewed from a position facing the surface of the resin layer, and the concave-convex structure is formed such that the standard deviation of the lengths along the second direction in the multiple geometric elements is larger than the standard deviation of the lengths along the first direction, and (g) the support includes at least two layers having different hardnesses. (h) of the two layers having different hardnesses, the layer having a higher hardness is disposed closer to the multilayer film layer than the layer having a lower hardness and is in contact with the resin layer, and the layer having a lower hardness constitutes the outermost surface; (i) the layer having a higher hardness has a thickness within the range of 10 μm to 100 μm, and the layer having a lower hardness has a thickness within the range of 50 μm to 300 μm that is thicker than the layer having a higher hardness. The gist of the present invention is as follows. Effect of the Invention

[0011] According to one aspect of the present invention, it is possible to provide a color-developing sheet, a color-developing article, a transfer foil, and a method for manufacturing a transfer foil, which are capable of suppressing damage to a multilayer film layer due to pulling. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram showing a cross-sectional structure of a transfer foil according to the first embodiment. [Diagram 2] FIG. 13 is a diagram showing a cross-sectional structure of a transfer foil according to a modified example. [Diagram 3] 4A and 4B are diagrams showing a transfer foil, in which FIG. 4A is a diagram showing a planar structure of a second uneven structure of a resin layer, and FIG. 4B is a diagram showing a cross-sectional structure of the second uneven structure of a resin layer. [Figure 4] FIG. 2 is a diagram showing a method for transferring a color-developing sheet, in which (a) is a diagram showing an adherend with a transfer foil attached, and (b) is a diagram showing the adherend to which the color-developing sheet has been transferred. [Diagram 5] FIG. 4 is a diagram showing a cross-sectional structure of the color-developing sheet after transfer. [Figure 6] A figure showing a transfer foil relating to the second embodiment, where (a) is a figure showing the planar structure of only the second convex element of the second uneven structure, and (b) is a figure showing the cross-sectional structure of the second uneven structure. [Figure 7] 4A and 4B are diagrams showing a transfer foil, in which FIG. 4A is a diagram showing a planar structure of a second uneven structure of a resin layer, and FIG. 4B is a diagram showing a cross-sectional structure of the second uneven structure of a resin layer.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are imposed for carrying out the present invention, but these limitations are not essential requirements for the present invention.

[0014] 1. First embodiment 1-1. Overall structure 1-2. Configuration of the second uneven structure 1-3. Manufacturing method of transfer foil 1-4. How to transfer the color-developing sheet 1-5. Effects of the First Embodiment 2. Second embodiment 2-1. Configuration of the second uneven structure 2-2. Configuration of the second protruding element 2-3. Configuration of the second uneven structure 2-4. Effects of the second embodiment 3. Examples and Comparative Examples 3-1.Example 3-2.Comparative Example 3-3.Evaluation

[0015] 1. First embodiment [1-1. Overall structure] FIG. 1 is a cross-sectional view showing the structure of a transfer foil 20 according to this embodiment. 1, the transfer foil 20 is formed by laminating a light absorbing layer 15 and an adhesive layer 16 in this order on a color-developing sheet 10. This allows the transfer foil 20 to attach (transfer) the color-developing sheet 10 to an adherend via the adhesive layer 16. The color-developing sheet 10 is formed by laminating a resin layer 12 (an example of a concave-convex structure layer), a multilayer film layer 13, and an anchor layer 14 in this order on a support 11. A light-absorbing layer 15 and an adhesive layer 16 are laminated on the surface of the color-developing sheet 10 facing the anchor layer 14, out of the two surfaces of the color-developing sheet 10.

[0016] The support 11 includes at least two layers (a pressure-resistant layer 11a and a cushion layer 11b) having different hardnesses. Fig. 1 illustrates a case where the support 11 is composed of only the pressure-resistant layer 11a and the cushion layer 11b. Fig. 1 also illustrates a case where the pressure-resistant layer 11a and the cushion layer 11b are not bonded to each other, but they may be bonded to each other via an adhesive layer or the like. The pressure-resistant layer 11a is the layer disposed on the resin layer 12 side of the two layers constituting the support 11, and is the layer with the higher hardness. As a result, the pressure-resistant layer 11a can suppress deformation of the resin layer 12 when forming the second uneven structure 12c (described later) of the resin layer 12, and can pattern the second uneven structure 12c in accordance with the shape of the plate (mold). The hardness of the pressure-resistant layer 11a is preferably 20 or more in type D of the JIS K7215 standard. For example, the measured hardness can be an average value obtained by measuring five points at approximately equal intervals in the film width direction of the pressure-resistant layer 11a. The hardness is preferably measured in an environment with a temperature of 25°C and a humidity of 50%. The melting point of the pressure-resistant layer 11a is preferably 90°C or more. Such a pressure-resistant layer 11a can suppress abnormal deformation of the resin layer 12 due to the plate pressure during transfer. In other words, it has the pressure resistance required for transfer. For example, if the pressure-resistant layer 11a is less than 20 in Type D of the JIS K7215 standard, the resin layer 12 may be abnormally deformed when the transfer foil 20 is transferred because the pressure applied during the transfer cannot withstand the pressure. Examples of materials that can be used for the pressure-resistant layer 11a include synthetic quartz substrates, polyethylene terephthalate (PET), polyester, vinyl chloride, polypropylene, polyethylene, and other resins. Such resins can improve the flexibility of the transfer foil 20. The thickness of the pressure-resistant layer 11a is preferably 10 μm or more and 100 μm or less from the viewpoints of pressure resistance and processability.

[0017] The cushion layer 11b is the layer arranged farther from the pressure-resistant layer 11a out of the two layers constituting the support 11, and is the layer with the lower hardness. As a result, the cushion layer 11b can reduce the hardness of the support 11 as a whole. Therefore, for example, after attaching the transfer foil 20 to the adherend, in order to reattach the transfer foil 20, the user pulls the transfer foil 20 so that the transfer foil 20 peels off from the adherend, and when the transfer foil 20 is given a tensile stress and the multilayer film layer 13 is deformed, the support 11 can be deformed in accordance with the deformation. Therefore, for example, compared to a method in which the support 11 is formed only with a high-hardness layer such as the pressure-resistant layer 11a, the deformation of the multilayer film layer 13 can be followed by the deformation of the support 11, and the multilayer film layer 13 can be reduced from receiving an external force due to the difference in the amount of deformation between the multilayer film layer 13 and the support 11, and damage to the multilayer film layer 13 can be suppressed. In other words, it has the tensile resistance required for reattachment. In addition, damage to the multilayer film layer 13 due to an external stimulus applied to the multilayer film layer 13 when the transfer foil 20 is attached can be suppressed. The hardness of the cushion layer 11b is preferably 95 or less in Type A of the JIS K6253-3 standard. For example, if the hardness is less than 95 in Type A of the JIS K6253-3 standard, the multilayer film layer 13 may be damaged by an external stimulus applied to the multilayer film layer 13 when the transfer foil 20 is attached. Examples of materials that can be used for the cushion layer 11b include resins such as polyurethane, polystyrene, polyolefin, and polyamide. The thickness of the cushion layer 11b is preferably thicker than that of the pressure-resistant layer 11a, since this makes it easier to protect the multilayer film layer 13. For example, from the viewpoint of protecting the multilayer film layer 13 from external stimuli and from the viewpoint of processability, the thickness is preferably 50 μm or more and 300 μm or less.

[0018] In addition, the cushion layer 11b has a releasability with respect to the resin layer 12. This allows the support 11 to be peeled off from the resin layer 12. The releasability of the cushion layer 11b is realized, for example, by selecting the material of the cushion layer 11b and the material of the resin layer 12 so that the adhesion between the cushion layer 11b and the resin layer 12 decreases. For example, at least one of the cushion layer 11b and the resin layer 12 contains silicone oil or a fluorine compound. The releasability of the cushion layer 11b may be promoted by an external physical stimulus such as heating or cooling. For example, when the resin layer 12 is made of a thermoplastic resin, the resin layer 12 is softened by heating, and the peeling of the support 11 from the resin layer 12 is promoted. The releasability of the cushion layer 11b may be promoted by an external physical stimulus such as heating or cooling. The releasability of the cushion layer 11b may be achieved by disposing a release layer containing a release agent between the support 11 and the resin layer 12. For example, silicone oil or a fluorine compound may be used as the release agent. When a release layer is disposed, an uneven structure may be formed at the interface between the cushion layer 11b (support 11) and the release layer. By forming such an uneven structure, it is possible to suppress the separation between the cushion layer 11b (support 11) and the release layer.

[0019] In the first embodiment, the support 11 is formed only from the pressure-resistant layer 11a and the cushion layer 11b, but other configurations may be adopted. For example, an intermediate layer may be disposed between the pressure-resistant layer 11a and the cushion layer 11b. As the intermediate layer, for example, an adhesive layer containing an acrylic adhesive, a urethane adhesive, a silicone adhesive, or the like, or a stress relaxation layer containing wax, oil, or the like may be adopted.

[0020] The resin layer 12 is a layer formed of a resin that transmits light in the visible region. In other words, it can be said that the resin layer 12 is a layer formed of a resin that is transparent to light in the visible region. This allows the resin layer 12 to transmit light that has entered the resin layer 12 from the surface on the support 11 side to the multilayer film layer 13. Examples of light in the visible region include light in a wavelength range of 360 nm or more and 830 nm or less. Examples of resins that are transparent to light in the visible region include photocurable resins, thermosetting resins, and thermoplastic resins. The surface of the resin layer 12 on the multilayer film layer 13 side has an uneven structure (hereinafter also referred to as a "second uneven structure 12c") that includes a plurality of irregularly arranged convex portions 12a and a plurality of concave portions 12b that are regions between the plurality of convex portions 12a.

[0021] The multilayer film 13 is a layer in which the refractive indexes of adjacent layers are different from each other. For example, the multilayer film 13 may be a layer in which high refractive index layers 13a and low refractive index layers 13b having a refractive index smaller than that of the high refractive index layers 13a are alternately laminated. In FIG. 1, the high refractive index layers 13a are in contact with the resin layer 12, and the low refractive index layers 13b are in contact with the anchor layer 14. The high refractive index layers 13a and the low refractive index layers 13b are formed from a material that transmits light in the visible range, that is, a material that is transparent to light in the visible range. For example, a dielectric thin film can be used as a material that is transparent to light in the visible range. For example, an inorganic material or an organic material can be used as a dielectric thin film. In particular, inorganic materials are preferred because they have a high density and are easier to increase the refractive index compared to organic materials. In addition, inorganic materials are less susceptible to thermal change, so it is easy to form a high-quality multilayer film 13 by physical deposition or chemical deposition of a thin layer. The materials of the high refractive index layer 13a and the low refractive index layer 13b are not limited as long as the refractive index of the high refractive index layer 13a is higher than that of the low refractive index layer 13b. However, the greater the difference in refractive index between the high refractive index layer 13a and the low refractive index layer 13b, the greater the intensity of reflected light can be obtained with a smaller number of layers. Therefore, for example, when inorganic materials are used as the materials of the high refractive index layer 13a and the low refractive index layer 13b, it is preferable that the material of the high refractive index layer 13a is titanium dioxide (TiO2) and the material of the low refractive index layer 13b is silicon dioxide (SiO2). Here, inorganic compounds are hard but brittle, and therefore, for example, when inorganic materials are used as the materials for the high refractive index layer 13a and the low refractive index layer 13b, the multilayer film 13 is more vulnerable to external stimuli (pressure during transfer, tensile stress during peeling) than when organic materials are used.

[0022] The multilayer film layer 13 has a shape that follows the second uneven structure 12c of the resin layer 12 so as to cover the entire surface of the resin layer 12 on the multilayer film layer 13 side with a constant thickness. The multilayer film layer 13 is discontinuous at the boundary between the part on the convex part 12a of the resin layer 12 and the part on the concave part 12b of the resin layer 12, but the material, thickness, and stacking order of each layer constituting the multilayer film layer 13 are the same between the part on the convex part 12a of the resin layer 12 and the part on the concave part 12b of the resin layer 12. Specifically, the surface of the multilayer film layer 13 on the resin layer 12 side (i.e., the surface on the support 11 side) has an uneven structure (hereinafter also referred to as the "first uneven structure 13c") having unevenness that is the inversion of the unevenness of the second uneven structure 12c of the resin layer 12. In other words, it can be said that the surface of the resin layer 12 on the multilayer film layer 13 side has the second uneven structure 12c having unevenness that is the inversion of the unevenness of the first uneven structure 13c. In addition, the surface of the multilayer film 13 facing the anchor layer 14 (i.e., the surface opposite to the surface facing the resin layer 12) has a third uneven structure 13d having a plurality of recesses that follow the second uneven structure 12c of the resin layer 12.

[0023] With this configuration, when light that has passed through the resin layer 12 enters the multilayer film layer 13, the light is reflected at each interface between the high refractive index layer 13a and the low refractive index layer 13b of the multilayer film layer 13, causing interference in the reflected light, and the direction of travel is changed due to the irregular unevenness on the outermost surface of the multilayer film layer 13, so that light in a specific wavelength range is emitted at a wide angle. In other words, the multilayer film layer 13 is configured so that the reflectance of light in a specific wavelength range of the light incident on the multilayer film layer 13 is higher than the reflectance of light in other wavelength ranges. The specific wavelength range is determined by the material and film thickness of the high refractive index layer 13a and the low refractive index layer 13b, as well as the width, height, and arrangement of the unevenness.

[0024] The thickness of the high refractive index layer 13a and the low refractive index layer 13b can be, for example, a thickness designed by the transfer matrix method or the like according to the desired color to be developed by the color-developing sheet 10. For example, when the color-developing sheet 10 exhibits blue color, the thickness of the high refractive index layer 13a made of TiO2 is preferably about 40 nm, and the thickness of the low refractive index layer 13b made of SiO2 is preferably about 75 nm.

[0025] In FIG. 1, the multilayer film layer 13 is formed of 10 layers, in which the high refractive index layer 13a and the low refractive index layer 13b are alternately stacked in this order from the resin layer 12 side. However, the number of layers and the order of stacking of the layers in the multilayer film layer 13 are not limited to this, and may be designed so as to emit a desired wavelength range. For example, the low refractive index layer 13b may be arranged so as to be in contact with the resin layer 12, and the high refractive index layer 13a and the low refractive index layer 13b may be alternately stacked on the low refractive index layer 13b. The layer in contact with the anchor layer 14 may also be either the high refractive index layer 13a or the low refractive index layer 13b. Furthermore, as long as the low refractive index layer 13b and the high refractive index layer 13a are alternately stacked, the layer in contact with the resin layer 12 and the layer in contact with the anchor layer 14 may be made of the same material. Furthermore, the multilayer film layer 13 may have three or more layers with different refractive indices. In other words, the multilayer film 13 should be configured so that adjacent layers in the multilayer film 13 have different refractive indices, and the reflectance of light incident on the multilayer film layer 13 in a specific wavelength range is higher than the reflectance in other wavelength ranges.

[0026] The anchor layer 14 is a layer for improving the adhesion between the light absorbing layer 15 and the multilayer film layer 13. Therefore, when the multilayer film layer 13 and the light absorbing layer 15 are directly adhered to each other, the anchor layer 14 is not necessarily required and can be omitted. As the material for the anchor layer 14, for example, a resin that develops adhesiveness by heating or a resin that has adhesiveness at room temperature can be used.

[0027] The glass transition point of the anchor layer 14 is preferably higher than the glass transition point of the adhesive layer 16. For example, 25° C. or higher can be used. This allows the anchor layer 14 to become glassy when attached to an adherend, thereby achieving an appropriate hardness. As the material for the anchor layer 14, for example, a thermoplastic resin such as polyethylene resin, polyvinyl acetate resin, acrylic resin, polyamide resin, polyester resin, polypropylene resin, or polyurethane resin can be used. In particular, polyester resin is preferable because it has high anchoring properties and is easy to obtain an appropriate hardness. In addition, the thermoplastic resin is preferably a copolymer. By using a copolymer, it is easy to achieve both hardness and anchoring properties (adhesiveness), which is suitable for protecting the multilayer film layer 13.

[0028] The light absorbing layer 15 is a layer for absorbing incident light transmitted through the resin layer 12 and the multilayer film layer 13. The light absorbing layer 15 contains a pigment and a binder resin. For example, carbon black, carbon nanotubes, titanium black, black iron oxide, and black complex oxide can be used as the pigment. For example, acrylic resin, polyester resin, polypropylene resin, and polyurethane resin can be used as the binder resin. In particular, polyester resin is preferable because the pigment is easily dispersed. For example, when the anchor layer 14 is a polyester resin, the binder resin of the light absorbing layer 15 is made of polyester resin, so that peeling failure during transfer between the anchor layer 14 and the light absorbing layer 15 can be suppressed, and further, reflection of incident light at the interface between the anchor layer 14 and the light absorbing layer 15 can be suppressed. For example, by making both the anchor layer 14 and the binder resin of the light absorbing layer 15 a resin having a hydroxyl group, peeling failure during transfer between the anchor layer 14 and the light absorbing layer 15 can be suppressed by hydrogen bonding of the hydroxyl group.

[0029] The glass transition point of the light absorbing layer 15 is preferably higher than the glass transition point of the adhesive layer 16. For example, 25°C or higher can be adopted. As a result, when the light absorbing layer 15 is attached to an adherend, it becomes glassy and can achieve an appropriate hardness. In addition, the difference between the glass transition point of the anchor layer 14 and the glass transition point of the light absorbing layer 15 is preferably 0 degrees or more and 70 degrees or less. In addition, 30 degrees or less is more preferable. If the difference in glass transition point between the anchor layer 14 and the light absorbing layer 15 is too large, peeling failure during transfer is likely to occur, but by setting it to 70 degrees or less, peeling failure can be suppressed, and further by setting it to 30 degrees or less, distortion of the light absorbing layer 15 can also be suppressed.

[0030] The adhesive layer 16 is a layer for attaching the transfer foil 20 to the adherend. For example, a layer having rubber-like properties when attached to the adherend can be used. For example, a resin having tackiness at room temperature, or a resin having no tackiness at room temperature but exhibiting tackiness when pressurized or heated can be used as the material for the adhesive layer 16. Tackiness refers to the sticky property of the surface of the adhesive layer 16. For example, a thermoplastic resin such as a polyethylene resin, a polyvinyl acetate resin, an acrylic resin, a polyamide resin, a polyester resin, a polypropylene resin, or a polyurethane resin can be used as the resin for the adhesive layer 16. In addition, the resin for the adhesive layer 16 may be cured by crosslinking or the like.

[0031] The glass transition point of the adhesive layer 16 is preferably lower than the glass transition point of the anchor layer 14 and the glass transition point of the light absorbing layer 15. For example, a temperature of less than 25° C. can be adopted. This allows the adhesive layer 16 to exhibit appropriate tackiness when attached to an adherend.

[0032] In addition, the adhesive layer 16 may be configured to have a property of absorbing incident light to the multilayer film layer 13, that is, a property of absorbing light transmitted through the resin layer 12 and the multilayer film layer 13, in addition to adhesion to the multilayer film layer 13. The degree of light absorption of the adhesive layer 16 can be evaluated by the transmittance of light in the visible region in the adhesive layer 16. For example, the optical transmittance of the adhesive layer 16 may be 50% or less. In addition, the optical transmittance of the adhesive layer 16 is preferably 40% or less, and more preferably 20% or less. For example, the optical transmittance is measured in accordance with JIS K7361, and the total light transmittance defined in JIS K7361 is measured. In addition, when measuring the optical transmittance, the adhesive layer 16 is separated from the color-developing sheet 10, and the measurement is performed on the adhesive layer 16 alone.

[0033] In addition, when the adhesive layer 16 is configured to have adhesion and light absorption, the light absorbing material may be, for example, a black inorganic pigment such as carbon black, carbon nanotubes, titanium black, black iron oxide, or black complex oxide. That is, the adhesive layer 16 is preferably a black layer containing a black inorganic pigment. In this case, the color of the adhesive layer 16 may be recognized as black by the naked eye. In addition, the color of the adhesive layer 16 is preferably a small L* value defined in the L*a*b* color system defined in JIS Z 8781. Specifically, the L* value is preferably 27 or less. This allows the adhesive layer 16 to adequately absorb the light transmitted through the multilayer film layer 13. In addition, the resin content in the adhesive layer 16 is preferably 2% by mass or more with respect to the total mass of the adhesive layer 16. If the resin content is 2% by mass or more, the light transmittance of the adhesive layer 16 can be easily adjusted to 50% or less.

[0034] In addition, as shown in FIG. 2, the adhesive layer 16 may have a three-layer structure in which a strong adhesive layer 16a, a base material 16b, and a weak adhesive layer 16c having a weaker adhesive strength than the strong adhesive layer 16a are laminated in this order from the light absorbing layer 15 side. As a result, when the user pulls the transfer foil 20, for example, the adhesive layer 16 causes peeling between the weak adhesive layer 16c and the adherend, so that peeling between the strong adhesive layer 16a and the light absorbing layer 15 can be suppressed, and the transfer foil 20 can be reattached. For example, a double-sided tape can be used as the adhesive layer 16 having a three-layer structure. For example, a thermoplastic resin such as a polyethylene resin, a polyvinyl acetate resin, an acrylic resin, a polyamide resin, a polyester resin, a polypropylene resin, or a polyurethane resin can be used as the material of the strong adhesive layer 16a and the weak adhesive layer 16c. For example, a resin such as a polyurethane resin, a polystyrene resin, a polyolefin resin, or a polyamide resin can be used as the base material 16b.

[0035] In addition, when the adhesive layer 16 has a three-layer structure, it is preferable that the glass transition point of the strong adhesive layer 16a and the glass transition point of the base material 16b are higher than the glass transition point of the weak adhesive layer 16c. For example, 25°C or higher can be adopted. As a result, the strong adhesive layer 16a and the base material 16b become glassy when attached to an adherend, and can realize an appropriate hardness. In addition, the glass transition point of the weak adhesive layer 16c can be, for example, less than 25°C. As a result, the weak adhesive layer 16c can exhibit an appropriate tackiness when attached to an adherend.

[0036] In addition to the above-mentioned layers, the transfer foil 20 may have a protective film (hereinafter also referred to as "separator") covering the surface of the adhesive layer 16 on the multilayer film layer 13 side and the opposite surface. This allows the separator to suppress the decrease in adhesiveness of the adhesive layer 16 during storage of the transfer foil 20. For example, a stretched film or a non-stretched film can be used as the separator. In particular, a stretched film is preferable because it is easy to form a thin and strong film and a thin separator can be realized. For example, a thermoplastic polymer can be used as the material of the separator. By using a thermoplastic polymer, a strong thin film film can be easily manufactured. For example, polyester, polyethylene, and polypropylene can be used as the thermoplastic polymer. These thermoplastic polymers have appropriate adhesiveness and peelability with the adhesive layer 16, and can also protect the adhesive layer 16. In addition, the separator may be subjected to a peeling treatment on one side or both sides. The peeling treatment allows the peeling force with the adhesive layer 16 to be adjusted, and the peeling failure of the multilayer film layer 13 due to the peeling force when peeling the separator can be reduced.

[0037] [1-2. Configuration of the second uneven structure] Next, the configuration of the second concave-convex structure 12c of the resin layer 12 will be described. Fig. 3(a) is a plan view of the resin layer 12 when viewed from the multilayer film layer 13 side. Fig. 3(b) is a cross-sectional view of the resin layer 12 when cut along line II in Fig. 3(a). In Fig. 3(a), the convex portions 12a constituting the second concavo-convex structure are indicated by dots.

[0038] As shown in FIG. 3(a), when viewed from the multilayer film layer 13 side, the convex portion 12a of the second concave-convex structure 12c forms a pattern consisting of a set of multiple geometric elements. As a pattern consisting of a set of multiple geometric elements, for example, a pattern consisting of a set of multiple rectangles R shown by dashed lines in the figure can be adopted. The rectangles R have a shape extending along the second direction Dy, and the length d2 along the second direction Dy is equal to or greater than the length d1 along the first direction Dx. As the first direction Dx and the second direction Dy, for example, two mutually orthogonal directions existing in a plane perpendicular to the thickness direction of the resin layer 12 can be adopted. In FIG. 3(a), each of the multiple rectangles R is arranged so as not to overlap with each other in either the first direction Dx or the second direction Dy.

[0039] Each of the rectangles R has a constant length d1 in the first direction Dx, and is arranged at intervals of the length d1 in the first direction Dx. That is, the rectangles R are arranged at a period of the length d1. Each of the rectangles R has an irregular length d2 in the second direction Dy, and the length d2 of each rectangle R is a value selected from a population having a predetermined standard deviation. For example, a normal distribution is preferable as the population. As a method for forming a pattern consisting of a plurality of rectangles R, for example, a method can be adopted in which a plurality of rectangles R (rectangles R having a length d2 distributed with a predetermined standard deviation) are provisionally laid out in a predetermined area, and the presence or absence of each of the provisionally laid out rectangles R is determined according to a certain probability, thereby determining an area in which the rectangles R are arranged and an area in which the rectangles R are not arranged. In order to efficiently scatter the reflected light from the multilayer film layer 13, it is preferable that the length d2 has a distribution with an average value of 4.15 μm or less and a standard deviation of 1 μm or less.

[0040] The convex portion 12a is disposed in the region where the rectangle R is disposed. In addition, when there are adjacent rectangles R, one convex portion 12a is disposed in one region where the regions where the adjacent rectangles R are disposed are joined. As a result, the length of the convex portion 12a in the first direction Dx is an integer multiple of the length d1 of the rectangle R. In addition, the length d1 in the first direction Dx of the rectangle R is preferably equal to or less than the wavelength of light in the visible region so that rainbow-colored light is not scattered by the unevenness of the multilayer film layer 13. That is, the length d1 of the rectangle R along the first direction Dx is set to be equal to or less than a sub-wavelength (equal to or less than the wavelength range of the incident light). For example, the length d1 is preferably equal to or less than 830 nm, and more preferably equal to or less than 700 nm. In addition, it is more preferable that the length d1 is smaller than the peak wavelength of the light in the above-mentioned specific wavelength range reflected from the multilayer film layer 13. For example, when the color-forming sheet 10 is to produce a blue color, the length d1 is preferably about 300 nm, when the color-forming sheet 10 is to produce a green color, the length d1 is preferably about 400 nm, and when the color-forming sheet 10 is to produce a red color, the length d1 is preferably about 460 nm.

[0041] Here, in order to increase the spread of the reflected light from the multilayer film layer 13, that is, to increase the scattering effect of the reflected light, it is preferable that the uneven structure has many undulations. For example, the ratio of the area occupied by the convex portions 12a to the unit area as viewed from a position facing the surface of the resin layer 12 is preferably 40% or more and 60% or less. For example, the ratio of the area occupied by the convex portions 12a to the unit area as viewed from a position facing the surface of the resin layer 12 is more preferably 50%. This makes the ratio of the area of ​​the convex portions 12a to the area of ​​the concave portions 12b 1:1.

[0042] 3(b), the height h1 of each of the multiple protrusions 12a is constant, and the protrusions 12a have a one-step shape from the plane on which the base of the protrusions 12a is located. The height h1 of the protrusions 12a can be set according to the desired color to be developed by the color-developing sheet 10, i.e., the wavelength range of light desired to be reflected by the color-developing sheet 10. For example, if the height h1 of the protrusions 12a is greater than the surface roughness of the multilayer film layer 13, a scattering effect of the reflected light can be obtained.

[0043] However, if the height h1 is excessively large, the scattering effect of the reflected light in the multilayer film layer 13 becomes too high, and the intensity of the reflected light is likely to be low. Therefore, for example, when the reflected light is light in the visible range, the height h1 is preferably 10 nm or more and 200 nm or less. For example, in a color-developing sheet 10 that exhibits blue, in order to obtain effective light diffusion, the height h1 is preferably about 40 nm or more and 150 nm or less. In addition, for example, in order to prevent the scattering effect from becoming too high, the height h1 is preferably 100 nm or less.

[0044] In order to suppress the interference of light caused by reflection from the unevenness of the multilayer film layer 13, the height h1 is preferably equal to or less than 1 / 2 the wavelength of light in the visible region. That is, 415 nm or less is preferable. Furthermore, in order to suppress the interference of light, the height h1 is more preferably equal to or less than 1 / 2 the peak wavelength of the light in the specific wavelength range reflected from the multilayer film layer 13.

[0045] The rectangles R may be arranged so that two rectangles R arranged along the first direction Dx partially overlap each other to form a pattern of the convex portion 12a. That is, the rectangles R may be arranged in the first direction Dx at an interval smaller than the length d1. The interval between the rectangles R may not be constant. In the overlapping rectangles R, one convex portion 12a is located in one area where the areas where the rectangles R are arranged are combined. In this case, the length in the first direction Dx of the convex portion 12a is different from an integer multiple of the length d1 of the rectangle R. The length d1 of the rectangle R may not be constant. That is, it is sufficient that each rectangle R satisfies the following conditions: the length d1 along the first direction Dx is equal to or smaller than a sub-wavelength, the length d2 along the second direction Dy is equal to or larger than the length d1 along the first direction Dx, and the standard deviation of the length d2 along the second direction Dy of the rectangles R is larger than the standard deviation of the length d1 along the first direction Dx. By satisfying these conditions, it is possible to obtain the scattering effect of the reflected light in the multilayer film layer 13, and light in a specific wavelength range can be observed as reflected light from the multilayer film layer 13 at a wide angle.

[0046] As described above, the first uneven structure 13c on the surface of the multilayer film 13 facing the resin layer 12 has unevenness that is the inverse of the unevenness of the second uneven structure 12c of the resin layer 12. Therefore, when viewed from the thickness direction of the multilayer film 13, the pattern formed by the recesses of the first uneven structure 13c is also a pattern consisting of a collection of multiple rectangles R, and has the same characteristics as the pattern formed by the protrusions 12a of the resin layer 12 in terms of the distribution of the widths of the rectangles R and the arrangement of the rectangles R. In addition, the depth of the recesses is consistent with the height h1 of the protrusions 12a, and is constant. In other words, the pattern constituted by the recesses of the first uneven structure 13c includes a pattern consisting of a set of multiple geometric elements (rectangles R) each having a length d1 along a first direction Dx that is equal to or less than a sub-wavelength and a length d2 along a second direction Dy perpendicular to the first direction Dx that is equal to or greater than the length along the first direction Dx, as viewed in the thickness direction of the multilayer film layer 13, and the standard deviation of the length d2 along the second direction Dy of the multiple geometric elements (rectangles R) is greater than the standard deviation of the length along the first direction Dx. Also, the recesses of the multilayer film layer 13 can be said to have a shape recessed by one step from the plane where the recesses open.

[0047] [1-3. Method of manufacturing transfer foil] Next, a method for producing the transfer foil 20 will be described. First, a support 11 including at least two layers (a pressure-resistant layer 11a and a cushion layer 11b having a lower hardness than the pressure-resistant layer 11a) with different hardness is prepared. Then, a resin layer 12 is formed on the pressure-resistant layer 11a side of the support 11. For example, a nanoimprint method can be used as a method for forming the second uneven structure 12c of the resin layer 12. For example, when using a photo-nanoimprint method, a mold is first formed as an intaglio plate having an inverted unevenness of the unevenness to be formed, and a coating liquid containing a material for the resin layer 12 is applied to the uneven surface of the mold. For example, synthetic quartz and silicon can be used as the material for the mold. For example, a known fine processing technique such as lithography and dry etching can be used as a method for forming the unevenness of the mold. For example, a photocurable resin can be used as the material for the resin layer 12. For example, a known coating method such as an inkjet method, a spray method, a bar coating method, a roll coating method, a slit coating method, and a gravure coating method can be used as a method for applying the coating liquid.

[0048] Next, the support 11 is placed on the surface of the layer made of the coating liquid, and while the support 11 and the mold are pressed against each other, light is irradiated from the side where the support 11 is located or the side where the mold is located. Next, the layer made of the cured resin and the support 11 are released from the mold. As a result, the unevenness of the mold is transferred to the resin, and a resin layer 12 having a second uneven structure 12c is formed, and a laminate made of the support 11 and the resin layer 12 is formed.

[0049] Also, for example, a coating liquid may be applied to the surface of the support 11, and a mold may be pressed against the layer of the coating liquid formed on the support 11, and light may be irradiated in the pressed state. Also, a thermal nanoimprinting method may be used instead of the photo nanoimprinting method. In this case, for example, a thermoplastic resin or a thermosetting resin may be used as the material for the resin layer 12.

[0050] Next, thin film layers (high refractive index layer 13a, low refractive index layer 13b) for constituting the multilayer film layer 13 are alternately laminated on the surface of the resin layer 12 opposite to the support 11. For example, when the high refractive index layer 13a and the low refractive index layer 13b are made of an inorganic material, known thin film formation techniques such as sputtering, vacuum deposition, and atomic layer deposition can be used to form the high refractive index layer 13a and the low refractive index layer 13b. For example, when the high refractive index layer 13a and the low refractive index layer 13b are made of an organic material, known techniques such as self-organization can be used.

[0051] Next, the anchor layer 14 is formed on the surface of the multilayer film 13 opposite to the resin layer 12. For example, known coating methods such as inkjet, spray, bar coating, roll coating, slit coating, and gravure coating can be used to form the anchor layer 14. In addition to the material of the anchor layer 14, a solvent may be mixed into the coating liquid for forming the anchor layer 14 as necessary. As the solvent, a solvent compatible with the resin of the material of the anchor layer 14 can be used. For example, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether, toluene, xylene, methylcyclohexane, ethylcyclohexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and the like can be used.

[0052] Next, the light absorbing layer 15 is formed on the surface of the anchor layer 14 opposite to the multilayer film layer 13. For example, known coating methods such as inkjet, spray, bar coating, roll coating, slit coating, and gravure coating can be used as the method for forming the light absorbing layer 15. In addition to the material of the light absorbing layer 15, a solvent may be mixed into the coating liquid for forming the light absorbing layer 15 as necessary. As the solvent, a solvent compatible with the resin of the material of the anchor layer 14 can be used. For example, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether, toluene, xylene, methylcyclohexane, ethylcyclohexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and the like can be used.

[0053] Next, the adhesive layer 16 is formed on the surface of the light absorbing layer 15 opposite to the anchor layer 14. For example, known coating methods such as inkjet, spray, bar coating, roll coating, slit coating, and gravure coating can be used as the method for forming the adhesive layer 16. In addition to the material of the adhesive layer 16, a solvent may be mixed into the coating liquid for forming the adhesive layer 16 as necessary. As the solvent, a solvent that is compatible with the resin of the material of the anchor layer 14 can be used. For example, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether, toluene, xylene, methylcyclohexane, ethylcyclohexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, etc. can be used. In addition, for example, a method can be used in which the adhesive layer 16 is formed using a film-like thermoplastic resin, that is, a hot melt film, etc., and heated with a heating laminator for use in adhesion.

[0054] By such a procedure, the transfer foil 20 can be manufactured. According to this manufacturing method, the transfer foil 20 can be obtained that is capable of absorbing light transmitted through the multilayer film layer 13 and has good adhesion between layers. In addition, since the second uneven structure 12c of the resin layer 12 is formed by using a nanoimprint method, a fine uneven structure can be suitably and easily formed.

[0055] [1-4. How to transfer color-developing sheets] Next, a method for transferring the color-developing sheet 10 from the transfer foil 20 to the adherend will be described. First, as shown in FIG. 4(a), the transfer foil 20 is attached to the adherend 61 so that the adhesive layer 16 is in contact with the adherend 61. The transfer foil 20 is attached to the adherend 61 with the support 11 facing outward. The adherend 61 is not particularly limited as long as it has a surface to which the adhesive layer 16 can be attached. Examples of the adherend 61 include resin molded products such as cards and three-dimensional objects, and paper. Next, as shown in FIG. 4(b), after the transfer foil 20 is attached to the adherend 61, the support 11 is peeled off from the transfer foil 20. For example, the support 11 is peeled off by applying a pulling force to the support 11 in the opposite direction to the adherend 61. At that time, the transfer foil 20 may be heated, pressed, irradiated with ultraviolet light, or the like to promote adhesion of the adhesive layer 16 to the adherend 61 and promote peeling of the support 11 from the color-developing sheet 10.

[0056] Through these procedures, the color-forming sheet 10 is transferred from the transfer foil 20 to the adherend 61, and the color-forming sheet 10 is fixed to the surface of the adherend 61. Then, a color-forming article 60 consisting of the color-forming sheet 10 and the adherend 61 is obtained. By transferring the color-forming sheet 10, the design of the adherend 61 can be improved, and also, the adherend 61 can be made more difficult to counterfeit.

[0057] 5, in the color-developing sheet 10 after being transferred to the adherend 61, the resin layer 12 constitutes the outermost surface exposed to the outside air, and the anchor layer 14 constitutes the outermost surface in contact with the adherend 61 via the adhesive layer 16. The structural color exhibited by the color-developing sheet 10 is observed from the resin layer 12 side.

[0058] [1-5. Effects of the first embodiment] Next, the effects of the first embodiment will be described. In the first embodiment, the support 11 includes at least two layers (pressure-resistant layer 11a, cushion layer 11b) with different hardness. Therefore, by including the pressure-resistant layer 11a with high hardness, abnormal deformation of the resin layer 12 due to plate pressure can be suppressed when the resin layer 12 directly contacting the pressure-resistant layer 11a is patterned, and a desired pattern can be easily formed. In particular, if the pressure-resistant layer 11a has a hardness of 20 or more according to type D of the JIS K7215 standard, abnormal deformation of the resin layer 12 due to plate pressure can be more appropriately suppressed. In contrast, if the support 11 is composed of the cushion layer 11b alone, for example, there is a possibility that the resin layer 12 will be abnormally deformed when the resin layer 12 is patterned.

[0059] In addition, by including the cushion layer 11b having a low hardness, the hardness of the support 11 as a whole can be reduced. Therefore, for example, after the transfer foil 20 is attached to the adherend, when the transfer foil 20 is pulled in order to reattach the transfer foil 20, damage to the multilayer film layer 13 due to an external stimulus applied to the multilayer film layer 13 during attachment of the transfer foil 20 can be suppressed. In particular, when the cushion layer 11b has a hardness of 95 or less in type A of the JIS K6253-3 standard, the cushion layer 11b has sufficient flexibility when attaching the transfer foil 20 to the adherend 61, and therefore can absorb the external stimulus applied to the multilayer film layer 13, and can more appropriately suppress damage to the multilayer film layer 13.

[0060] Therefore, by forming the support 11 into a layered structure including at least the pressure-resistant layer 11a and the cushion layer 11b having different hardnesses, the resin layer 12 can be patterned normally and the impact of an external stimulus applied to the multilayer film layer 13 can be suppressed. In other words, the resin layer 12 can be formed into a desired shape, and cracks or chips in the multilayer film layer 13, and thus defects in the appearance of the color-developing sheet 10, can be suppressed.

[0061] Moreover, in the first embodiment, after the support 11 is peeled off, the first uneven structure 13c of the multilayer film layer 13 is covered with the resin layer 12. Moreover, the third uneven structure 13d of the multilayer film layer 13 is covered with the anchor layer 14, the light absorbing layer 15, and the adhesive layer 16. Therefore, when the color-forming sheet 10 is transferred, the support 11 is peeled off while the multilayer film layer 13 remains protected, so that defects in the color-forming sheet 10 can be suppressed and the thickness of the color-forming sheet 10 can be reduced.

[0062] In the first embodiment, the glass transition points of the anchor layer 14 and the light absorbing layer 15, which are sequentially laminated on the multilayer film layer 13, are each set to 25° C. or higher, and the glass transition point of the adhesive layer 16, which is then laminated, is set to 25° C. or lower. Therefore, the anchor layer 14 and the light absorbing layer 15, which have high hardness, can protect the multilayer film layer 13 from defects caused by physical damage due to scratches, etc., and the adhesive layer 16, which is in direct contact with the adherend 61 and has low hardness and flexibility, can suppress damage caused by external stimuli such as folding or bending, and ultimately poor appearance of the color-developing sheet 10.

[0063] In the first embodiment, the cushion layer 11b is configured to have a releasability with respect to the resin layer 12. Therefore, the support 11, that is, the support 11 that is the base material at the time of manufacture, can be peeled off after the transfer of the color-developing sheet 10, so that the flexibility of the color-developing sheet 10 can be improved. Therefore, even if the surface of the adherend is curved, the color-developing sheet 10 can be easily made to follow the surface of the adherend. As a result, the load on the color-developing sheet 10 at the time of attachment can be reduced, and peeling of the color-developing sheet 10 after attachment can be suppressed. Furthermore, compared to the case where the color-developing sheet 10 has the base material at the time of manufacture, the thickness of the color-developing sheet 10 can be made thinner, and the portion to which the color-developing sheet 10 is attached in the color-developing article can be suppressed from swelling. Therefore, for example, when the color-developing sheet 10 is used for decoration, the decorativeness can be enhanced.

[0064] In the first embodiment, in the color-developing sheet 10 after transfer, the second uneven structure 12c of the multilayer film layer 13 is covered with the resin layer 12. In addition, the third uneven structure 13d of the multilayer film layer 13 is covered with the anchor layer 14, the light absorbing layer 15, and the adhesive layer 16. Therefore, the first uneven structure 13c and the third uneven structure 13d of the multilayer film layer 13 are protected, and deformation and damage of the first uneven structure 13c and the third uneven structure 13d of the multilayer film layer 13 having an optical function can be suppressed compared to when the first uneven structure 13c and the third uneven structure 13d are exposed to the outside.

[0065] 2. Second embodiment [2-1. Configuration of the second uneven structure] Next, a second embodiment of the color-developing sheet, the color-developing article, the transfer foil, and the method for manufacturing the transfer foil will be described with reference to Fig. 6 and Fig. 7. In the following, the differences between the second embodiment and the first embodiment will be mainly described, and the same reference numerals will be used to designate the same configurations as the first embodiment, and the description thereof will be omitted.

[0066] FIG. 6(a) is a plan view showing only the second convex elements of the concave-convex structure when viewed from the multilayer film layer 13 side. FIG. 6(b) is a cross-sectional view of the concave-convex structure when cut along line II-II in FIG. 6(a). In FIG. 6(a), the second convex elements are indicated by dots. FIG. 7(a) is a plan view of the resin layer 12 when viewed from the multilayer film layer 13 side. FIG. 7(b) is a cross-sectional view of the resin layer 12 when cut along line III-III in FIG. 7(a). In FIG. 7(a), the first convex elements and the second convex elements are indicated by dots of different densities. As shown in Figures 6 and 7, the second embodiment differs from the first embodiment in the configuration of the second uneven structure 12c of the resin layer 12. The transfer foil 20 and the color-developing sheet 10 of the second embodiment have the same configuration as the first embodiment except for the configuration of the second uneven structure 12c. Specifically, the convex portion 12a of the second uneven structure 12c of the resin layer 12 has a structure in which the first convex portion element 12Ea shown in Figure 7(a) having the same configuration as the convex portion 12a of the first embodiment and the second convex portion element 12Eb extending in a strip shape shown in Figure 6(b) are superimposed in the thickness direction of the resin layer 12.

[0067] Here, in the color-developing sheet 10 of the first embodiment, the change in the color observed due to the observation angle is gradual due to the scattering effect of the reflected light, but the vividness of the color observed is likely to decrease due to the decrease in the intensity of the reflected light caused by scattering. Depending on the application of the color-developing sheet 10, a sheet that allows more vivid colors to be observed at a wide observation angle may be required. In contrast, in the color-developing sheet 10 of the second embodiment, the second convex elements are arranged so that the incident light is strongly diffracted in a specific direction, and the light scattering effect based on the first convex elements 12Ea and the light diffraction effect based on the second convex elements allow more vivid colors to be observed at a wide observation angle.

[0068] [2-2. Configuration of the second convex element] Next, the configuration of the second convex elements 12Eb of the second concave-convex structure 12c will be described. As shown in Fig. 6(a), when viewed from the multilayer film layer 13 side, the second protrusion elements 12Eb have a belt shape of a constant width extending along the second direction Dy and are arranged at intervals in the first direction Dx. In other words, the pattern formed by the second protrusion elements 12Eb can be said to be a pattern consisting of a plurality of belt-shaped regions extending along the second direction Dy and arranged along the first direction Dx. The length d3 of the second protrusion elements 12Eb in the first direction Dx may be the same as or different from the length d1 (see Fig. 3(a)) of the rectangle R that determines the pattern of the first protrusion elements 12Ea.

[0069] The arrangement interval de of the second convex elements 12Eb in the first direction Dx, i.e., the arrangement interval of the stripe regions in the first direction Dx, is set so that at least a part of the reflected light on the surface of the concave-convex structure constituted by the second convex elements 12Eb is observed as first-order diffracted light. The first-order diffracted light is diffracted light whose diffraction order m is 1 or -1. That is, when the incident angle of the incident light is θ, the reflection angle of the reflected light is φ, and the wavelength of the diffracted light is λ, the arrangement interval de is set so as to satisfy de≧λ / (sinθ+sinφ). For example, when a visible ray of λ=360 nm is targeted, the arrangement interval de of the second convex elements 12Eb may be 180 nm or more. That is, the arrangement interval de may be ½ or more of the minimum wavelength in the wavelength range included in the incident light. The arrangement interval de is the distance along the first direction Dx between the ends of two adjacent second convex elements 12Eb located on the same side (the right side in FIG. 7(a)).

[0070] Moreover, the periodicity of the pattern constituted by the second convex elements 12Eb is reflected in the periodicity of the second concave-convex structure 12c of the resin layer 12, and is reflected in the periodicity of the first concave-convex structure 13c on the outermost surface of the multilayer film layer 13. Therefore, when the arrangement interval de of the multiple second convex elements 12Eb is constant, reflected light of a predetermined wavelength is emitted at a predetermined angle from the multilayer film layer 13 due to diffraction on the outermost surface of the multilayer film layer 13. The reflection intensity of light due to diffraction is much stronger than the reflection intensity of reflected light caused by the light scattering effect based on the convex parts 12a of the first embodiment (the first convex elements 12Ea of the second embodiment), so light having a brilliance like metallic luster is visually recognized, but on the other hand, dispersion due to diffraction occurs, and the visual color changes according to the change in the observation angle.

[0071] Therefore, even if the structure of the first convex elements 12Ea is designed to obtain a color-developing sheet 10 that exhibits blue color, if the arrangement interval de of the second convex elements 12Eb is set to a constant value of about 400 nm to 5 μm, light due to strong green to red surface reflection caused by diffraction is observed depending on the observation angle. Also, if the arrangement interval de of the second convex elements 12Eb is increased to about 50 μm, for example, the range of angles at which light in the visible region is diffracted becomes narrow, so that color changes caused by diffraction become difficult to see, but light with a brilliance such as metallic luster is only observed at a specific observation angle. In contrast, for example, by not setting the arrangement interval de to a constant value and making the pattern of the second convex elements 12Eb a pattern in which multiple periodic structures with different periods are superimposed, multiple wavelengths of light are mixed in the reflected light due to diffraction, so that highly monochromatic light that has been dispersed becomes difficult to see. Therefore, glossy, vivid colors are observed at a wide observation angle. When the arrangement interval de is not constant, for example, the arrangement interval de can be selected from the range of 360 nm or more and 5 μm or less, and the average value of the arrangement intervals de of the multiple second convex elements 12Eb can be set to be equal to or more than 1 / 2 of the minimum wavelength in the wavelength range contained in the incident light.

[0072] However, as the standard deviation of the arrangement interval de increases, the arrangement of the second convex elements 12Eb becomes irregular, the scattering effect becomes dominant, and it becomes difficult to obtain strong reflection by diffraction. Therefore, it is preferable to determine the arrangement interval de of the second convex elements 12Eb so that the reflected light by diffraction is emitted in a range approximately equal to the range of the light spreading according to the angle at which the light spreads due to the light scattering effect based on the first convex elements 12Ea. For example, when the reflected blue light is emitted in a range of ±40° with respect to the incident angle, the arrangement interval de in the pattern of the second convex elements 12Eb is set so that its average value is 1 μm or more and 5 μm or less, and the standard deviation is about 1 μm. By setting such an arrangement interval de, the reflected light by diffraction can be emitted at an angle approximately equal to the angle at which the light spreads due to the light scattering effect based on the first convex elements 12Ea.

[0073] In other words, the uneven structure based on the second convex elements 12Eb is different from the second uneven structure 12c of the first embodiment which diffracts and extracts light of a specific wavelength range, and can be said to be a structure for utilizing diffraction to emit light of various wavelength ranges within a specified angular range by variance in the arrangement spacing de.

[0074] Furthermore, in order to generate a diffraction phenomenon with a longer period, a square region with one side of 10 μm to 100 μm may be used as the unit region, and in the pattern of the second convex elements 12Eb for each unit region, the average arrangement interval de may be 1 μm to 5 μm, with a standard deviation of about 1 μm. Note that the multiple unit regions may include a region in which the arrangement interval de is a constant value within the range of 1 μm to 5 μm. Even if there is a unit region with a constant arrangement interval de, if the arrangement interval de varies with a standard deviation of about 1 μm in this unit region and any of the unit regions adjacent to this unit region, an effect equivalent to that of a configuration in which the arrangement interval de varies in all unit regions can be expected in terms of the resolution of the human eye.

[0075] In addition, FIG. 6(a) shows a case where the second convex elements 12Eb have periodicity due to the arrangement interval de only in the first direction Dx. However, the light scattering effect based on the first convex elements 12Ea mainly acts on the reflected light in the direction along the first direction Dx when viewed from a position facing the surface of the multilayer film layer 13, but may also affect a part of the reflected light in the direction along the second direction Dy. Therefore, the second convex elements 12Eb may also have periodicity in the second direction Dy. That is, the pattern of the second convex elements 12Eb may be a pattern in which a plurality of strip-shaped regions extending in the second direction Dy are arranged along each of the first direction Dx and the second direction Dy.

[0076] In such a pattern of the second protrusion elements 12Eb, for example, the arrangement intervals de along the first direction Dx of the strip region and the arrangement intervals along the second direction Dy may each have a variation such that their average values ​​are 1 μm or more and 100 μm or less. In addition, depending on the difference between the influence of the light scattering effect based on the first protrusion elements 12Ea on the first direction Dx and the influence of the light scattering effect on the second direction Dy, the average value of the arrangement intervals de along the first direction Dx and the average value of the arrangement intervals along the second direction Dy may be different from each other, and further the standard deviation of the arrangement intervals de along the first direction Dx and the standard deviation of the arrangement intervals along the second direction Dy may be different from each other.

[0077] The height h2 of the second convex element 12Eb may be larger than the surface roughness of the multilayer film layer 13 on the convex portion 12a and the concave portion 12b. However, as the height h2 becomes larger, the diffraction effect based on the second convex element 12Eb becomes dominant in the effect of the concave-convex structure on the reflected light, and the light scattering effect based on the first convex element 12Ea becomes difficult to obtain. Therefore, the height h2 is preferably about the same as the height h1 of the first convex element 12Ea, and the height h2 may be equal to the height h1. For example, the height h1 of the first convex element 12Ea and the height h2 of the second convex element 12Eb are each preferably 10 nm or more and 200 nm or less, and in the color-developing sheet 10 that exhibits blue, they are preferably 10 nm or more and 150 nm or less.

[0078] [2-3. Configuration of the second protruding portion structure] Next, the configuration of the second concave-convex structure 12c of the resin layer 12 will be described. As shown in Fig. 7(a), when viewed from the multilayer film layer 13 side, the pattern formed by the convex portion 12a is a pattern in which a first pattern formed by the first convex portion element 12Ea and a second pattern formed by the second convex portion element 12Eb are overlapped. That is, the region in which the convex portion 12a is located includes a region S1 formed only by the first convex portion element 12Ea, a region S2 in which the first convex portion element 12Ea and the second convex portion element 12Eb overlap, and a region S3 formed only by the second convex portion element 12Eb. In Fig. 7(a), the first convex portion element 12Ea and the second convex portion element 12Eb are overlapped so that their ends are aligned in the first direction Dx, but this is not limited thereto, and the end of the first convex portion element 12Ea and the end of the second convex portion element 12Eb may be overlapped with a shift.

[0079] As shown in FIG. 7(b), in the region S1, the height of the protrusion 12a is the height h1 of the first protrusion element 12Ea. In the region S2, the height of the protrusion 12a is the sum of the height h1 of the first protrusion element 12Ea and the height h2 of the second protrusion element 12Eb. In the region S3, the height of the protrusion 12a is the height h2 of the second protrusion element 12Eb. In this way, the protrusion 12a has a multi-step shape in which the first protrusion element 12Ea having a predetermined height h1, whose projected image in the thickness direction of the resin layer 12 constitutes a first pattern, and the second protrusion element 12Eb having a predetermined height h2, whose projected image in the thickness direction constitutes a second pattern, are stacked in the height direction.

[0080] The pattern formed by the first convex element 12Ea and the pattern formed by the second convex element 12Eb may be arranged so that the first convex element 12Ea and the second convex element 12Eb do not overlap. Even with such an arrangement, the light scattering effect based on the first convex element 12Ea and the light diffraction effect based on the second convex element 12Eb can be obtained. However, if the first convex element 12Ea and the second convex element 12Eb are arranged so that they do not overlap each other, the area in which the first convex element 12Ea can be arranged per unit area becomes small, and the light scattering effect may decrease. Therefore, in order to increase the light scattering effect and the diffraction effect based on the first and second convex elements 12Ea and 12Eb, it is preferable to overlap the first convex element 12Ea and the second convex element 12Eb to make the convex 12a into a multi-step shape as shown in FIG. 7(b).

[0081] As described above, the color-developing sheet 10 of the second embodiment causes a light diffusion phenomenon due to the first convex elements 12Ea and a light diffraction phenomenon due to the second convex elements 12Eb. Therefore, due to the synergistic effect of these, reflected light of a specific wavelength range can be observed at a wide observation angle, and the intensity of the reflected light is increased, resulting in a glossy, vivid color.

[0082] As described above, the first uneven structure 13c on the surface of the multilayer film layer 13 facing the resin layer 12 has unevenness that is the inversion of the unevenness of the second uneven structure 12c of the resin layer 12. Therefore, when viewed from the thickness direction of the multilayer film layer 13, the pattern formed by the recesses of the first uneven structure 13c is a pattern in which a pattern formed by the first recess elements formed by the inversion of the first protrusion elements 12Ea and a pattern formed by the second recess elements formed by the inversion of the second protrusion elements 12Eb are superimposed. In addition, the pattern formed by the first recess elements, i.e., the pattern formed by the projected image of the first recess elements in the thickness direction of the multilayer film layer 13, has the same characteristics as the first pattern formed by the first protrusion elements 12Ea of the resin layer 12 in terms of the distribution of the width of the rectangle R and the arrangement of the rectangle R. In addition, the pattern formed by the second recess elements, i.e., the pattern formed by the projected images of the second recess elements in the thickness direction of the multilayer film layer 13, has similar characteristics to the second pattern formed by the second convex elements 12Eb of the resin layer 12 in terms of the width and arrangement of the band-shaped regions.

[0083] The recess on the surface of the multilayer film layer 13 facing the resin layer 12 has a multi-step shape in which the first recess element and the second recess element are arranged in the depth direction. In a region consisting of only the first recess element, the depth of the recess is equal to the height h1 of the first protrusion element 12Ea. In a region where the first recess element and the second recess element overlap, the depth of the recess is equal to the sum of the height h1 of the first protrusion element 12Ea and the height h2 of the second protrusion element 12Eb. In a region consisting of only the second recess element, the depth of the recess is equal to the height h2 of the second protrusion element 12Eb.

[0084] In other words, the pattern formed by the recesses of the first uneven structure 13c is a pattern in which a first pattern consisting of a collection of multiple geometric elements (rectangles R) and a second pattern consisting of multiple strip-shaped regions extending along the second direction and aligned along the first direction Dx are superimposed, the arrangement interval of the strip-shaped regions along the first direction Dx is not constant and its average value is equal to or greater than half the minimum wavelength in the wavelength range contained in the incident light, and the recesses of the first uneven structure 13c have a multi-step shape in which recess elements having a predetermined depth h1 and whose projected image in the thickness direction of the multilayer film layer 13 is an element that constitutes the first pattern, and recess elements having a predetermined depth h2 and whose projected image in the thickness direction of the multilayer film layer 13 is an element that constitutes the second pattern, are aligned in the depth direction.

[0085] In the second embodiment, the color-developing sheet 10 is transferred from the transfer foil 20 to the adherend in the same manner as in the first embodiment. That is, as shown in Fig. 4(a), the transfer foil 20 is attached to the adherend 61 so that the adhesive layer 16 contacts the adherend 61, and then, as shown in Fig. 4(b), the support 11 is peeled off from the transfer foil 20. As a result, the color-developing sheet 10 is transferred from the transfer foil 20 to the adherend 61, and a color-developing article 60 composed of the color-developing sheet 10 and the adherend 61 is obtained.

[0086] In the color-forming sheet 10 after being transferred to the adherend, the resin layer 12 constitutes the outermost surface exposed to the outside air, and the anchor layer 14 constitutes the outermost surface in contact with the adherend 61 via the adhesive layer 16, as in the first embodiment. The structural color exhibited by the color-forming sheet 10 is observed from the resin layer 12 side.

[0087] Also, in the second embodiment, similarly to the first embodiment, the support 11 includes at least two layers (pressure-resistant layer 11a, cushion layer 11b) with different hardnesses. Therefore, for example, when patterning the resin layer 12 that is in direct contact with the pressure-resistant layer 11a with high hardness, abnormal deformation of the resin layer 12 due to plate pressure can be suppressed. Also, for example, when attaching the transfer foil 20 to the adherend 61, the cushion layer 11b with low hardness can suppress the impact of an external stimulus applied to the multilayer film layer 13. Also, for example, when the transfer foil 20 is pulled to reattach the transfer foil 20 after attaching it to the adherend, damage to the multilayer film layer 13 can be suppressed. Therefore, cracks and chips in the multilayer film layer 13, and thus poor appearance of the color-developing sheet 10 can be suppressed.

[0088] 3. Examples and Comparative Examples Next, the above-mentioned color-developing sheet, color-developing article, transfer foil, and method for producing the transfer foil will be described using specific examples and comparative examples. [3-1. Example] First, a mold, which is an intaglio plate used in the photo nanoimprinting method, was prepared. Specifically, since the photo nanoimprinting method uses light with a wavelength of 365 nm, synthetic quartz, which transmits light of this wavelength, was used as the material for the mold. In forming the mold, a film made of chromium (Cr) was first formed on the surface of a synthetic quartz substrate by sputtering, and an electron beam resist pattern was formed on the Cr film by electron beam lithography. The pattern was a pattern consisting of a collection of multiple rectangles R. The length of the rectangles R in the first direction Dx was 300 nm, and the length of the rectangles R in the second direction Dy was a length selected from a normal distribution with an average of 2000 nm and a standard deviation of 500 nm. In the above pattern, the multiple rectangles R were arranged so as not to overlap in the first direction. A positive type electron beam resist was used, and its film thickness was 200 nm.

[0089] Next, the Cr film in the area exposed from the resist was etched by plasma generated by applying high frequency to a mixed gas of chlorine (Cl2) and oxygen (O2). Next, the synthetic quartz substrate in the area exposed from the resist and the Cr film was etched by plasma generated by applying high frequency to ethane hexafluoride gas. The etching depth of the synthetic quartz substrate was 70 nm. Next, the remaining resist and Cr film were removed from the surface of the synthetic quartz substrate to obtain a synthetic quartz substrate on which a concave-convex structure corresponding to the first convex element 12Ea was formed.

[0090] Next, a film made of Cr was formed by sputtering on the surface of the synthetic quartz substrate on which the concave-convex structure was formed, and an electron beam resist pattern was formed on the Cr film by electron beam lithography. The pattern was a pattern consisting of a plurality of stripe regions. The length of the stripe region in the first direction Dx was 200 nm, and the length of the stripe region in the second direction Dy was 94 μm. For each rectangular region having a length of 40 μm in the first direction Dx and a length of 94 μm in the second direction Dy, the stripe regions were arranged with an average arrangement interval in the first direction Dx of 1.5 μm and a standard deviation of 0.5 μm. A positive type electron beam resist was used, and its film thickness was 200 nm.

[0091] Next, the Cr film in the area exposed from the resist was etched by plasma generated by applying high frequency to a mixed gas of chlorine (Cl2) and oxygen (O2). Next, the synthetic quartz substrate in the area exposed from the resist and the Cr film was etched by plasma generated by applying high frequency to ethane hexafluoride gas. The etching depth of the synthetic quartz substrate was 65 nm. Next, the remaining resist and Cr film were removed from the surface of the synthetic quartz substrate, and then Optool HD-1100 (manufactured by Daikin Industries) was applied as a mold release agent to the surface of the synthetic quartz substrate. As a result, a concave-convex structure corresponding to the second convex element 12Eb was formed, and a mold in which a concave-convex structure corresponding to the second concave-convex structure 12 of the resin layer 12 of the second embodiment was formed was obtained.

[0092] Next, a photocurable resin (PAK-02, manufactured by Toyo Gosei) was applied to the polyester film (pressure-resistant layer 11a) surface of the support 11, which was made of a two-layer structure of a polyester film (pressure-resistant layer 11a) and a polyurethane film (cushion layer 11b). Next, the surface of the mold on which the irregularities were formed was pressed against the applied photocurable resin, and light of 365 nm was irradiated from the back side of the mold. Next, the photocurable resin was cured by the irradiation of light to form a resin layer 12, and then the resin layer 12 and the support 11 were peeled off from the mold. As a result, a laminate was obtained of the resin layer 12 having an irregular structure and the support 11 made of a two-layer structure of a polyester film (pressure-resistant layer 11a) and a polyurethane film (cushion layer 11b).

[0093] Next, on the uneven surface of the laminate, TiO2 films as the high refractive index layer 13a having a thickness of 40 nm and SiO2 films as the low refractive index layer 13b having a thickness of 75 nm were alternately formed by vacuum deposition, and five pairs of the high refractive index layer 13a and the low refractive index layer 13b, that is, a multilayer film layer 13 having 10 layers was formed. Next, a coating liquid of a copolymer polyester having a glass transition point of 60°C was applied to the upper surface of the multilayer film layer 13 by using a bar coating method, and the formed coating film was dried at 80°C for 10 minutes to form an anchor layer 14. The thickness of the anchor layer 14 was about 5 μm. Next, a black pigment having a glass transition point of 200°C was applied on the anchor layer 14 by using a bar coating method, and the formed coating film was dried at 100°C for 20 minutes to form a light absorbing layer 15. The thickness of the light absorbing layer 15 was about 10 μm. Next, a polyurethane coating liquid having a glass transition point of 20° C. was applied onto the light absorbing layer 15 by a bar coating method, and the formed coating film was dried at 80° C. for 1 minute to form an adhesive layer 16. The thickness of the adhesive layer 16 was about 5 μm. By the above procedure, the transfer foil 20 of the embodiment was produced.

[0094] Next, the transfer foil 20 was attached to a polypropylene adherend using a three-dimensional overlay lamination method, and the support 11 was peeled off to obtain a color-developed article 60 of the embodiment. In detail, the adhesive layer 16 of the transfer foil 20 was placed in a molding machine facing the adherend, and the inside of the molding machine was evacuated and then heated to 160°C to bring the transfer foil 20 into contact with the adherend. In this state, pressure was applied to the side where the transfer foil 20 was located up to atmospheric pressure, thereby integrating the transfer foil 20 and the adherend. Next, the support 11 was peeled off from the adherend. Then, unnecessary parts of the color-developing sheet 10 were cut off to produce a color-developing article decorated with the color-developing sheet 10.

[0095] [3-2. Comparative Example] Comparative Example 1 In Comparative Example 1, a support 11 consisting of only a polyester film (pressure-resistant layer 11a) was used, and a transfer foil 20 of Comparative Example 1 was produced by the same process as in the Example. Then, a color-developed article of Comparative Example 1 was produced from the transfer foil 20 of Comparative Example 1 by the same method as in the Example.

[0096] Comparative Example 2 In Comparative Example 2, a support 11 consisting of only a polyurethane film (cushion layer 11b) was used, and the transfer foil 20 of Comparative Example 1 was produced by the same process as in Example. Then, the color-developed article of Comparative Example 1 was produced from the transfer foil 20 of Comparative Example 2 by the same method as in Example.

[0097] Comparative Example 3 In Comparative Example 3, the adhesive layer 16 was formed by applying a coating liquid of an acrylic resin having a glass transition point of 100° C. by a bar coating method, and drying the formed coating film at 120° C. for 1 minute. The other steps were the same as in the examples, and the transfer foil 20 of Comparative Example 3 was produced. Then, the color-developed article of Comparative Example 3 was produced from the transfer foil 20 of Comparative Example 1 by the same method as in the examples.

[0098] [3-3. Evaluation items] The evaluation items of the examples and comparative examples 1 to 3 will be explained below. (First appearance observation) The appearance of the colored articles of Example and Comparative Examples 1 to 3 was observed, and the presence or absence of appearance defects was judged. (Second external observation) After the transfer foils 20 of the examples and comparative examples 1 to 3 were attached to the adherend, the transfer foils 20 were peeled off from the adherend, and the peeled transfer foils 20 were reattached to the adherend to produce colored articles. The appearance of the produced colored articles was then observed to determine whether or not there was a defect in appearance.

[0099] [3-4. Evaluation Results] Table 1 shows the evaluation results of Examples and Comparative Examples 1 to 3. [Table 1]

[0100] According to Table 1, the evaluation result of the "first appearance observation" of the example was "○", which is a pass. When the color-developing article of the example was observed, a glossy blue color was observed on the color-developing sheet 10, and there were no appearance defects such as cracks or chips on the color-developing sheet 10. On the other hand, the evaluation results of the "first appearance observation" of the comparative example 1 and the comparative example 3 were "△", which is a fail. When the color-developing article of the comparative example 1 was observed, a color other than blue was observed on the color-developing sheet 10, and the color-developing sheet 10 had an appearance defect such as cracks or chips. When the color-developing article of the comparative example 3 was observed, a blue color was observed on the color-developing sheet 10, but the color-developing sheet 10 had an appearance defect such as cracks or chips. Furthermore, the evaluation result of the "first appearance observation" of the comparative example 2 was "×", which is a fail. When the color-developing article of the comparative example 2 was observed, a color other than blue was observed on the color-developing sheet 10. When observed with a scanning electron microscope (SEM), the resin layer 12 was abnormally deformed. This is because the support 11 was made of only a polyurethane film and was therefore unable to support the resin, causing the resin to deform under the pressure of the plate.

[0101] Also, according to Table 1, the evaluation result of the "second appearance observation" of the example was "○", which is a pass. When the color-developing article of the example was observed, a glossy blue color was observed on the color-developing sheet 10, as in the "first appearance observation", and the color-developing sheet 10 did not have any cracks or chips in its appearance. On the other hand, the evaluation results of the "second appearance observation" of the comparative examples 1 and 2 were "×", which is a fail. When the color-developing article of the comparative example 1 was observed, the cracks and chips in the color-developing sheet 10 spread, and the appearance defect worsened. Note that the color-developing article of the comparative example 2 was already "×" at the time of the "first appearance observation", so it was also "×" in the "second appearance observation". Also, the evaluation result of the "second appearance observation" of the comparative example 3 was "△", which is a fail. When the color-developing article of the comparative example 3 was observed, the cracks and chips in the color-developing sheet 10 hardly spread, so the evaluation result was the same as the "first appearance observation".

[0102] It was confirmed that by configuring the support 11 to include at least two layers (pressure-resistant layer 11a and cushion layer 11b) with different hardness, damage to the multilayer film layer 13 can be suppressed when the transfer foil 20 is pulled to re-attach the transfer foil 20. [Explanation of symbols]

[0103] Reference Signs List 10...color-developing sheet, 11...support, 11a...pressure-resistant layer, 11b...cushion layer, 12...resin layer, 12Ea...first convex element, 12Eb...second convex element, 12a...convex portion, 12b...concave portion, 12c...second concave-convex structure, 13...multilayer film layer, 13a...high refractive index layer, 13b...low refractive index layer, 13c...first concave-convex structure, 13d...third concave-convex structure, 14...anchor layer, 15...light-absorbing layer, 16...adhesive layer, 16a...strong adhesive layer, 16b...substrate, 16c...weak adhesive layer, 20...transfer foil, 60...color-developing article, 61...adherend

Claims

1. A support, a multilayer film layer formed on the support, and a resin layer disposed between the support and the multilayer film layer, the multilayer film is configured such that adjacent layers in the multilayer film have mutually different refractive indices, and a reflectance of light in a specific wavelength range among light incident on the multilayer film layer is higher than a reflectance of light in other wavelength ranges; the surface of the multilayer film facing the support has a first uneven structure having a plurality of recesses; a pattern formed by the recesses includes a pattern consisting of a set of a plurality of geometric elements, each having a length along a first direction that is equal to or less than a subwavelength and a length along a second direction perpendicular to the first direction that is equal to or greater than the length along the first direction, as viewed along a thickness direction of the multilayer film; a standard deviation of lengths of the plurality of graphic elements along the second direction is greater than a standard deviation of lengths of the plurality of graphic elements along the first direction; The support includes at least two layers having different hardnesses, of the two layers having different hardnesses, the layer having a higher hardness is disposed closer to the multilayer film layer than the layer having a lower hardness and is in contact with the resin layer, the layer having a lower hardness forming an outermost surface, The thickness of the layer having a higher hardness is in the range of 10 μm to 100 μm, The thickness of the layer having a lower hardness is thicker than the thickness of the layer having a higher hardness, and is within a range of 50 μm to 300 μm. Coloring sheet.

2. Of the two layers having different hardnesses, the layer having a lower hardness has a hardness of 95 or less in Type A of JIS K6253-3, and the layer having a higher hardness has a hardness of 20 or more in Type D of JIS K7215. The color-developing sheet according to claim 1 .

3. The surface of the resin layer facing the multilayer film layer has a second uneven structure having an inverted unevenness of the first uneven structure of the multilayer film layer, The surface of the multilayer film opposite to the surface on the resin layer side has a third uneven structure having a plurality of recesses following the second uneven structure of the resin layer. The color-developing sheet according to claim 1 or 2.

4. The depth of each of the plurality of recesses in the first uneven structure is uniform. The color-developing sheet according to any one of claims 1 to 3.

5. a pattern formed by the recesses of the first unevenness structure is a pattern in which a first pattern formed by a set of the plurality of graphic elements and a second pattern formed by a plurality of strip-shaped regions extending along the second direction and aligned along the first direction are superimposed on each other; an arrangement interval of the strip-shaped regions along the first direction is not constant, and an average value of the arrangement interval is equal to or greater than half of a minimum wavelength in a wavelength range included in the incident light, The recesses of the first uneven structure have a multi-step shape in which recess elements, whose projected images in the thickness direction of the multilayer film layer are elements that constitute the first pattern and have a predetermined depth, and recess elements, whose projected images in the thickness direction of the multilayer film layer are elements that constitute the second pattern and have a predetermined depth, are arranged in a depth direction. The color-developing sheet according to any one of claims 1 to 4.

6. The color-developing sheet according to any one of claims 1 to 5, and an adherend to which the color-developing sheet is attached. Color-developing items.

7. a support; a concave-convex structure layer formed on the support and having a concave-convex structure on a surface opposite to the support; a multilayer film layer formed on the concave-convex structure layer and having a surface shape following the concave-convex structure; an anchor layer formed on the multilayer film layer; a light absorbing layer formed on the anchor layer; and an adhesive layer formed on the light absorbing layer; The multilayer film has adjacent layers each having a different refractive index, and the reflectance of light in a specific wavelength range among the light incident on the multilayer film is different from the reflectance of light in another wavelength range. It is configured higher than When viewed from the multilayer film layer side, the convex portions constituting the uneven structure include a pattern constituted by a set of a plurality of geometric elements each having a length along a first direction that is equal to or less than a sub-wavelength and a length along a second direction perpendicular to the first direction that is equal to or greater than the length along the first direction, and the standard deviation of the lengths along the second direction of the plurality of geometric elements is greater than the standard deviation of the lengths along the first direction, The support includes at least two layers having different hardnesses, of the two layers having different hardnesses, the layer having a higher hardness is disposed closer to the multilayer film layer than the layer having a lower hardness and is in contact with the relief structure layer, the layer having a lower hardness constitutes an outermost surface, The thickness of the layer having a higher hardness is in the range of 10 μm to 100 μm, The thickness of the layer having a lower hardness is thicker than the thickness of the layer having a higher hardness, and is within a range of 50 to 300 μm. Transfer foil.

8. The support is configured to be peelable from the relief structure layer. The transfer foil according to claim 7.

9. The anchor layer and the light absorbing layer each have a higher glass transition point than the adhesive layer. The transfer foil according to claim 7 or 8.

10. each of the anchor layer and the light absorbing layer has a glass transition point of 25° C. or higher; The adhesive layer has a glass transition temperature of less than 25° C. The transfer foil according to claim 9.

11. The adhesive layer is formed by laminating, in this order from the light absorbing layer side, a strong adhesive layer, a base material, and a weak adhesive layer having a weaker adhesive strength than the strong adhesive layer. The transfer foil according to claim 9 or 10.

12. The glass transition point of the strong adhesive layer and the glass transition point of the base material are each higher than the glass transition point of the weak adhesive layer. The transfer foil according to claim 11.

13. The glass transition point of the strong adhesive layer and the glass transition point of the base material are each 25° C. or higher, The glass transition temperature of the weak adhesive layer is less than 25° C. The transfer foil according to claim 12.

14. A step of forming a resin layer having a concave-convex structure on one surface of a support; forming a multilayer film along the concave-convex structure such that adjacent layers in the multilayer film have different refractive indices, and a reflectance of light in a specific wavelength range among light incident on the multilayer film layer is higher than a reflectance of light in other wavelength ranges; forming an anchor layer on a surface of the multilayer film opposite to the surface on the resin layer side; forming a light absorbing layer on a surface of the anchor layer opposite to the multilayer film; forming an adhesive layer on a surface of the light absorbing layer opposite to the anchor layer; In the step of forming the resin layer, a pattern constituted by one or more steps of convex portions constituting the uneven structure includes a pattern consisting of a set of a plurality of geometric elements each having a length along a first direction that is equal to or less than a sub-wavelength and a length along a second direction perpendicular to the first direction that is equal to or greater than the length along the first direction, when viewed from a position facing the surface of the resin layer, and the uneven structure is formed such that a standard deviation of the lengths along the second direction in the plurality of geometric elements is larger than a standard deviation of the lengths along the first direction; The support includes at least two layers having different hardnesses, of the two layers having different hardnesses, the layer having a higher hardness is disposed closer to the multilayer film layer than the layer having a lower hardness and is in contact with the resin layer, the layer having a lower hardness forming an outermost surface, The thickness of the layer having a higher hardness is in the range of 10 μm to 100 μm, The thickness of the layer having a lower hardness is thicker than the thickness of the layer having a higher hardness, and is within a range of 50 μm to 300 μm. A method for manufacturing transfer foil.

Images