Recording medium and exterior member

Abstract

This recording medium is provided with: a recording layer configured to be capable of changing a coloring state with an external stimulus; and a plurality of transparent convex parts provided on the recording layer. The convex parts have a width A greater than or equal to a width W of a coloring part. The recording layer has a plurality of coloring parts. A pitch Δd' of the coloring parts and the width W of the coloring parts satisfy the relationship Δd' > W, or the pitch Δd' of the coloring parts change in an in-plane direction of the recording layer.

Description

[Technical Field]

[0001] The present disclosure relates to a recording medium and an exterior member including the same. [Background technology]

[0002] In recent years, development of recording media on which images can be drawn by irradiating laser light has been progressing as an example of display media to replace printed matter. For example, Patent Document 1 discloses a recording medium in which a plurality of reversible thermosensitive coloring compositions with different color tones are separately and independently provided in the surface direction of a supporting substrate, and the plurality of reversible thermosensitive coloring compositions each contain a light-to-heat conversion material that absorbs infrared rays in a different wavelength range and generates heat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-188827 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the above-mentioned recording medium has a structure on its surface, there is a problem that when an image is drawn by irradiating it with laser light, deviations in color density and color mixture occur, resulting in a decrease in display quality.

[0005] An object of the present disclosure is to provide a recording medium that can suppress a decrease in display quality even when a structure is provided on the surface, and an exterior member including the same. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the first disclosure provides: Laser light irradiation a recording layer configured so that its color state can be changed by a plurality of light-transmitting structures provided on the recording layer; Equipped with The structure includes a curved surface, The recording layer is Corresponding to image pixels having a plurality of color-forming portions, The pitch Δd' of the colored area changes in one direction, The recording medium is one in which the pitch Δd′ of the color-forming portions in one direction and the width W of the color-forming portions in one direction satisfy the relationship Δd′>W.

[0007] The second disclosure is: Laser light irradiation a recording layer configured so that its color state can be changed by a plurality of light-transmitting structures provided on the recording layer; Equipped with the structure includes a plane inclined with respect to the surface of the recording layer; The recording layer is Corresponding to image pixels having a plurality of color-forming portions, The pitch Δd' of the colored area changes in one direction, The recording medium is one in which the pitch Δd′ of the color-forming portions in one direction and the width W of the color-forming portions in one direction satisfy the relationship Δd′>W.

[0008] A third disclosure is an exterior member including the recording medium of the first disclosure or the second disclosure. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing an example of the configuration of a recording medium according to the first embodiment. [Figure 2] Fig. 2A is a cross-sectional view taken along line IIA-IIA in Fig. 1. Fig. 2B is a cross-sectional view taken along line IIB-IIB in Fig. 1. [Figure 3] FIG. 3 is a schematic diagram for explaining a method for calculating the pitch Δd′X of the color-developing portions. [Figure 4] FIG. 4 is a perspective view showing an example of the configuration of a recording medium according to the second embodiment. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6]Fig. 6A is a perspective view showing an example of the configuration of a recording medium according to the third embodiment, and Fig. 6B is a plan view showing an example of the configuration of a recording medium according to the third embodiment. [Figure 7] Fig. 7A is a cross-sectional view taken along line VIIA-VIIA in Fig. 6B, and Fig. 7B is a cross-sectional view taken along line VIIB-VIIB in Fig. 6B. [Figure 8] Fig. 8A is a cross-sectional view showing an example of the configuration of a recording medium according to the fourth embodiment, and Fig. 8B is a cross-sectional view showing the configuration of a recording layer as a reference example. [Figure 9] FIG. 9 is a cross-sectional view showing an example of the configuration of a recording medium according to the fifth embodiment. [Figure 10] 10A to 10D are cross-sectional views showing examples of the configuration of recording media according to modifications. [Figure 11] 11A to 11C are cross-sectional views showing examples of the configuration of recording media according to modified examples. [Figure 12] 12A to 12C are cross-sectional views showing examples of the configuration of recording media according to modifications. [Figure 13] Fig. 13A is a perspective view showing the external configuration of the front surface of the smartphone, and Fig. 13B is a perspective view showing the external configuration of the rear surface of the smartphone shown in Fig. 13A. [Figure 14] FIG. 14 is a perspective view showing an example of the appearance of a nail tip. [Figure 15] Fig. 15A is a plan view showing an example of the appearance of a nail seal, and Fig. 15B is a cross-sectional view taken along line XVB-XVB in Fig. 15A. DETAILED DESCRIPTION OF THE INVENTION

[0010] The embodiments of the present disclosure will be described in the following order: In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. 1. First embodiment (example of recording medium having a plurality of structures one-dimensionally arranged on the surface) 2. Second embodiment (example of recording medium having a plurality of structures one-dimensionally arranged on the surface) 3. Third embodiment (example of recording medium having a plurality of structures two-dimensionally arranged on the surface) 4. Fourth embodiment (example of recording medium capable of multicolor display with multi-layered recording layer structure) 5. Fifth embodiment (example of recording medium capable of multicolor display with a single-layer recording layer) 6. Variations 7 Application Examples

[0011] <1 First Embodiment> [Storage medium configuration] FIG. 1 is a perspective view showing an example of the configuration of a recording medium 10 according to the first embodiment. FIG. 2A is a cross-sectional view taken along line IIA-IIA in FIG. 1. FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG. 1. The recording medium 10 is a recording medium whose coloring state can be changed by external stimuli such as laser light irradiation or heat. The recording medium 10 may be a reversible recording medium or a non-reversible recording medium. The recording medium 10 includes a support substrate 11, a recording layer 12 provided on the support substrate 11, and a plurality of structures 13 provided on the recording layer 12. The recording medium 10 may further include an intermediate layer 13A between the recording layer 12 and the plurality of structures 13. Note that FIGS. 1A, 2A, and 2B are schematic representations of the configuration of the recording medium 10 and may differ from the actual dimensions and shape.

[0012] In this specification, axes that are orthogonal to each other in the plane of the recording layer 12 are referred to as the X-axis and the Y-axis, respectively, and an axis that is perpendicular to the surface of the recording layer 12 is referred to as the Z-axis. Y Assuming that the grid points are arranged two-dimensionally at intervals of , the position of the nth grid point in the X-axis direction and the mth grid point in the Y-axis direction is P n,m The position of the structure 13 on the surface is expressed as this position P n,m It is expressed using

[0013] (Support base) The support substrate 11 is for supporting the recording layer 12. The support substrate 11 is preferably made of a material that has excellent heat resistance and dimensional stability in the planar direction. The support substrate 11 may be either optically transparent or non-optically transparent. The support substrate 11 may have a specific color, such as white. The support substrate 11 may be, for example, a rigid substrate such as a wafer, or may be flexible thin glass, film, paper, or the like. By using a flexible substrate as the support substrate 11, a flexible (foldable) recording medium 10 can be realized. Although FIGS. 1, 2A, and 2B show an example in which the main surface of the support substrate 11 is flat, the main surface of the support substrate 11 may also be curved.

[0014] Examples of the constituent material of the support base 11 include inorganic materials, metal materials, and polymeric materials such as plastics. Specifically, examples of inorganic materials include silicon (Si), silicon oxide (SiO X ), silicon nitride (SiN X ) or aluminum oxide (AlO X ) Examples of the silicon oxide include glass and spin-on glass (SOG). Examples of the metal material include aluminum (Al), nickel (Ni), and stainless steel. Examples of the polymer material include polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethyl ether ketone (PEEK), polyvinyl chloride (PVC), and copolymers thereof. The support substrate 11 may contain glitter.

[0015] A reflective layer (not shown) may be provided on the upper or lower surface of the support base 11, or the support base 11 itself may also function as a reflective layer. When the support base 11 has such a configuration, it becomes possible to display clearer colors.

[0016] (recording layer) The recording layer 12 is configured so that its color state can be changed by external stimuli such as laser light irradiation or heat. The recording layer 12 is configured using a material that allows stable recording and can control the coloring state. Specifically, it contains a color-forming compound with electron-donating properties (electron-donating dye) and an electron-accepting substance. A color reaction occurs between the electron-donating dye and the electron-accepting substance due to the external stimulus (laser light irradiation), and the irradiated portion develops color. This forms an image on the recording layer 12. Here, the image is not limited to images such as designs, color patterns, and photographs, but also includes text such as letters and symbols.

[0017] The recording layer 12 preferably further contains a photothermal conversion material or a polymer material, and more preferably contains both of these materials. In addition to the above materials, the recording layer 12 may also contain various additives such as a sensitizer or an ultraviolet absorber. The thickness of the recording layer 12 is, for example, 1 μm or more and 10 μm or less.

[0018] Examples of the color-forming compound include leuco dyes. Examples of the leuco dye include existing dyes for thermal paper. Specific examples include compounds containing an electron-donating group in the molecule, as represented by the following formula (1):

[0019] [ka]

[0020] The color former is not particularly limited and can be appropriately selected depending on the purpose. Specific examples of the color former include the compound shown in formula (1) above, as well as fluoran compounds, triphenylmethanephthalide compounds, azaphthalide compounds, phenothiazine compounds, leucoauramine compounds, and indolinophthalide compounds. Other examples include 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-di(n-butylamino)fluoran, 2-anilino-3-methyl-6-(Nn-propyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-isopropyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-isobutyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(Nn-amyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-sec-butyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(Nn-amyl-N-ethylamino)fluoran, 2-anilino-3-methyl-6-( N-iso-amyl-N-ethylamino)fluoran, 2-anilino-3-methyl-6-(Nn-propyl-N-isopropylamino)fluoran, 2-anilino-3-methyl-6-(N-cyclohexyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-ethyl-p-toluidino)fluoran, 2-anilino-3-methyl-6-(N-methyl-p-toluidino)fluoran, 2-(m-trichloromethylanilino)-3-methyl-6-diethylaminofluoran, 2-(m-trifluoromethylanilino)-3-methyl-6-diethylaminofluoran, 2-(m-trichloromethylanilino)-3-methyl-6-(N-cyclohexyl-N-methylamino)fluoran, 2-(2,4-dimethylanilino)-3-methyl-6-diethylaminofluoran, 2-(N-ethyl-p-toluidino)-3-methyl-6-(N-ethylanilino)fluoran, 2-(N-ethyl-p-toluidino)-3-methyl-6-(N-propyl-p-toluidino)fluoran, 2-anilino-6-(Nn-hexyl-N-ethylamino)fluoran, 2-(o-chloroanilino)-6-diethylaminofluoran, 2-(o-chloroanilino)-6-dibutylaminofluoran, 2-(m-trifluoromethylanilino)-6-diethylaminofluoran, 2,3-dimethyl-6-dimethylaminofluoran, 3-methyl-6-(N-ethyl-p-toluidino)fluoran, 2-chloro-6 -Diethylaminofluoran, 2-bromo-6-diethylaminofluoran, 2-chloro-6-dipropylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 3-bromo-6-cyclohexylaminofluoran, 2-chloro-6-(N-ethyl-N-isoamylamino)fluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-(o-chloroanilino)-3-chloro-6-cyclohexylaminofluoran, 2-(m-trifluoromethylanilino)-3-chloro-6-diethylaminofluoran, 2-(2,3-dichloroanilino)-3-chloro-6-diethylaminofluoran, 1,2-Benzo-6-diethylaminofluoran, 3-diethylamino-6-(m-trifluoromethylanilino)fluoran, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-7-azaphthalide, 3-(1-octyl- 2-Methylindol-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-methyl-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-methyl-4-diethylaminophenyl)-7-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-methyl-4-diethylaminophenyl)-7-azaphthalide 3-(1-ethyl-2-methylindol-3-yl)-3-(4-Nn-amyl-N-methylaminophenyl)-4-azaphthalide, 3-(1-methyl-2-methylindol-3-yl)-3-(2-hexyloxy-4-diethylaminophenyl)-4-azaphthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide phenyl)-4-azaphthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-7-azaphthalide, 2-(p-acetylanilino)-6-(Nn-amyl-Nn-butylamino)fluoran, 2-benzylamino-6-(N-ethyl-p-toluidino)fluoran, 2-benzylamino-6-(N-methyl-2,4-dimethylanilino)fluoran, 2-benzylamino-6-(N-ethyl-2,4-dimethylanilino)fluoran, 2-benzylamino-6-(N-methyl-p-toluidino)fluoran, 2-benzylamino-6-(N-ethyl-p-toluidino)fluoran, 2-(di-p-methylbenzylamino)-6-(N-ethyl-p-toluidino)fluoran, 2-(α-phenylethylamino)-6-(N-ethyl-p-toluidino)fluoran, 2-methylamino-6-(N-methylanilino)fluoran, 2-methylamino-6-(N-ethylanilino)fluoran, 2-methylamino-6-(N-propylanilino)fluoran , 2-ethylamino-6-(N-methyl-p-toluidino)fluoran, 2-methylamino-6-(N-methyl-2,4-dimethylanilino)fluoran, 2-ethylamino-6-(N-ethyl-2,4-dimethylanilino)fluoran, 2-dimethylamino-6-(N-methylanilino)fluoran, 2-dimethylamino-6-(N-ethylanilino)fluoran, 2-diethylamino-6-(N-methyl-p-toluidino)fluoran, 2-diethylamino-6-(N-ethyl-p-toluidino)fluoran, 2-dipropylamino-6-(N-methyl 2-amino-6-(N-propylanilino)fluoran, 2-dipropylamino-6-(N-ethylanilino)fluoran, 2-amino-6-(N-methylanilino)fluoran, 2-amino-6-(N-ethylanilino)fluoran, 2-amino-6-(N-propylanilino)fluoran, 2-amino-6-(N-methyl-p-toluidino)fluoran, 2-amino-6-(N-ethyl-p-toluidino)fluoran, 2-amino-6-(N-propyl-p-toluidino)fluoran, 2-amino-6-(N-methyl-p-ethylanilino)fluoran, 2-amino-6-(N-ethylanilino)fluoran 2-amino-6-(N-propyl-p-ethylanilino)fluoran, 2-amino-6-(N-methyl-2,4-dimethylanilino)fluoran, 2-amino-6-(N-ethyl-2,4-dimethylanilino)fluoran, 2-amino-6-(N-propyl-2,4-dimethylanilino)fluoran, 2-amino-6-(N-methyl-p-chloroanilino)fluoran, 2-amino-6-(N-ethyl-p-chloroanilino)fluoran, 2-amino-6-(N-propyl-p-chloroanilino)fluoran, 1,Examples include 2-benzo-6-(N-ethyl-N-isoamylamino)fluoran, 1,2-benzo-6-dibutylaminofluoran, 1,2-benzo-6-(N-methyl-N-cyclohexylamino)fluoran, and 1,2-benzo-6-(N-ethyl-N-toluidino)fluoran.

[0021] An electron-accepting substance is a color-developing / decoloring agent for a color-forming compound. Electron-accepting substances are used, for example, to color a colorless color-forming compound or to decolorize a color-forming compound that exhibits a predetermined color. Examples of color-developing / decoloring agents include compounds having a salicylic acid skeleton shown in the following formula (2) and containing an electron-accepting group in the molecule.

[0022] [ka] (wherein X is any one of -NHCO-, -CONH-, -NHCONH-, -CONHCO-, -NHNHCO-, -CONHNH-, -CONHNHCO-, -NHCOCONH-, -NHCONHCO-, -CONHCONH-, -NHNHCONH-, -NHCONHNH-, -CONHNHCONH-, -NHCONHNHCO-, and -CONHNHCONH-; and R is a linear hydrocarbon group having from 25 to 34 carbon atoms.)

[0023] Photothermal conversion materials generate heat by absorbing light in a predetermined wavelength range in the near-infrared region. As the photothermal conversion material, it is preferable to use a near-infrared absorbing dye that has an absorption peak in the wavelength range of 700 nm to 2000 nm and has almost no absorption in the visible region. Specific examples include compounds having a phthalocyanine skeleton (phthalocyanine dyes), compounds having a squarylium skeleton (squaryllium dyes), and inorganic compounds. Examples of inorganic compounds include metal complexes such as dithio complexes, diimonium salts, aminium salts, and inorganic compounds. Examples of inorganic compounds include graphite, carbon black, metal powder particles, metal oxides such as tricobalt tetroxide, iron oxide, chromium oxide, copper oxide, titanium black, and ITO (indium tin oxide), metal nitrides such as niobium nitride, metal carbides such as tantalum carbide, metal sulfides, and various magnetic powders. In addition, compounds having a cyanine skeleton (cyanine dyes), which have excellent light resistance and heat resistance, may also be used. Here, excellent light resistance means that the compound does not decompose when irradiated with laser light. Excellent heat resistance means that, for example, when formed into a film together with a polymer material and stored at 150°C for 30 minutes, the maximum absorption peak value of the absorption spectrum does not change by 20% or more. Examples of such compounds having a cyanine skeleton include those having, in the molecule, a counter ion selected from SbF6, PF6, BF4, ClO4, CF3SO3, and (CF3SO3)2N, and at least one of a methine chain containing a five-membered ring or a six-membered ring. Note that the compound having a cyanine skeleton used in the recording medium 10 according to the first embodiment preferably has both one of the counter ions and a cyclic structure such as a five-membered ring or a six-membered ring in the methine chain, but sufficient light resistance and heat resistance are ensured if it has at least one of these.

[0024] The polymer material preferably functions as a binder. The polymer material is preferably one in which the color former, electron acceptor, and photothermal conversion material can be easily and uniformly dispersed. Examples of the polymer material include at least one of thermosetting resins and thermoplastic resins. Specific examples include at least one selected from the group consisting of polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, ethyl cellulose, polystyrene, styrene copolymers, phenoxy resins, polyesters, aromatic polyesters, polyurethanes, polycarbonates, polyacrylic acid esters, polymethacrylic acid esters, acrylic acid copolymers, maleic acid polymers, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, and starch.

[0025] The recording layer 12 has a plurality of color-forming portions 12A and a plurality of non-color-forming portions 12B. The color-forming portions 12A correspond to pixels of an image recorded in the recording layer 12. The plurality of color-forming portions 12A are arranged within the plane of the recording layer 12. An image is formed by the plurality of color-forming portions 12A. The color-forming portions 12A contain a color-forming compound in a colored state.

[0026] The non-coloring portions 12B are provided between adjacent coloring portions 12A. The non-coloring portions 12B separate adjacent coloring portions 12A and prevent adjacent coloring portions 12A from overlapping. The coloring portions 12A contain a color-forming compound in a decolorized state.

[0027] Pitch Δd′ of the color-producing portion 12A in the X-axis direction X and the width W of the color-forming portion 12A in the X-axis direction X and Δd' X >W X This satisfies the relationship shown in FIG. 1. This makes it possible to prevent adjacent color producing sections 12A from overlapping with each other in the X-axis direction. Therefore, it is possible to prevent the color density from deviating from the desired color density in the areas where the color producing sections 12A overlap with each other in the X-axis direction.

[0028] Pitch Δd′ of the color-forming portion 12A in the Y-axis direction Yand the width W of the color-forming portion 12A in the Y-axis direction Y and Δd' Y >W Y This satisfies the relationship shown in FIG. 1. This makes it possible to prevent adjacent color producing sections 12A from overlapping with each other in the Y-axis direction. Therefore, it is possible to prevent the color density from deviating from the desired color density in the areas where the color producing sections 12A overlap with each other in the Y-axis direction.

[0029] Pitch Δd′ of the color-producing portion 12A in the X-axis direction X 2A, changes in the X-axis direction (in-plane direction of the recording layer 12). More specifically, when the position P n,m The light L incident on the color-producing section 12A reaches the position P' n, m If we reach position P', n,m The pitch Δd' of the color-forming portion 12A in X is the position P n,m The surface inclination α of the structure 13 at X However, the steeper the position P n,m indicates the position of the surface of the structure 13 in the in-plane direction of the recording layer 12. Also, the inclination α X indicates the inclination of the surface of the structure 13 in the X-axis direction, that is, the inclination of the structure 13 in the XZ cross section.

[0030] The pitch Δd′ of the color-forming portion 12A in the Y-axis direction Y is constant in the Y-axis direction, as shown in Figure 2B.

[0031] As mentioned above, the pitch Δd' X changes in the X-axis direction, and the pitch Δd' Y is constant in the Y-axis direction, when the image drawn on the recording layer 12 is viewed from the Z-axis direction through the structures 13, it becomes an image without distortion in the X-axis direction (hereinafter referred to as "normal image"). In contrast, when the image drawn on the recording layer 12 is viewed from the Z-axis direction with the structures 13 removed, it becomes an image distorted in the X-axis direction with respect to the normal image.

[0032] FIG. 3 shows the pitch Δd′ of the color-forming portion 12A. X 10 is a schematic diagram for explaining a method for calculating the pitch Δd′ of the color forming portion 12A. X is obtained as follows: The relative refractive index n of the structure 13 with respect to air (refractive index n0=1), that is, the refractive index n of the structure 13, is expressed by the following formula (1) according to Snell's law. n=sinθ n+1,m / sinθ' n+1,m =sinθ n,m / sinθ' n,m ···(1) (However, θ n,m :Position P n,m The incident angle of the laser beam L incident on n,m :Position P n ,m The refraction angle (outgoing angle) of the laser light L incident on the n+1,m :Position P n+1,m The incident angle of the laser beam L incident on n+1,m :Position P n+1,m The refraction angle (outgoing angle) of the laser light L incident on the n,m : The position of the nth grid point in the X-axis direction and the mth grid point in the Y-axis direction, P n +1,m : The position of the (n+1)th grid point in the X-axis direction and the mth grid point in the Y-axis direction)

[0033] Pitch Δd' of color-forming portion 12A X is expressed by the following equation (2a). Δd' X =Δd X -(l n+1,m sinθ' n+1,m -l n,m sinθ' n ,m ) (2a) (However, n+1,m :Position P n+1,m , P' n+1,m The distance between n,m :Position P n,m , P' n,m Distance between, Δd X : Laser beam feed pitch in the X-axis direction (position P n,m , position P n+1,mdistance between the n,m : the position of the nth color-forming portion 12A in the X-axis direction and the mth color-forming portion 12A in the Y-axis direction, P' n+1,m : the position of the (n+1)th color-forming unit 12A in the X-axis direction and the mth color-forming unit 12A in the Y-axis direction) The position of the color-forming portion 12A refers to the center position of the color-forming portion 12A.

[0034] Using equation (1), sinθ' n+1,m , sinθ' n,m are sinθ' respectively n+1,m =sinθ n+1 / n, sinθ' n,m =sinθ n / n, the above formula (2a) can be expressed as follows: Δd' X =Δd X -(1 / n)×(l n+1,m sinθ n+1,m -l n,m sinθ n,m ) (2b)

[0035] (structure) The structures 13 are pillars extending in the Y-axis direction (first direction) so as to maintain their cross-sectional shape. The structures 13 are arrayed one-dimensionally in the X-axis direction (second direction) so that their pillar surfaces face each other. The pillar surfaces of the pillars are composed of a first surface S1 and a second surface S2 extending in the Y-axis direction. A ridgeline is provided between the first surface S1 and the second surface S2. The first surface S1 is a convex curved surface, such as an arched surface. The second surface S2 is a flat surface. This flat surface is approximately perpendicular to the surface of the recording layer 12. The angle θ between the bottom surface of the structure 13 and the flat surface is preferably 80 degrees or more and 100 degrees or less, more preferably 85 degrees or more and 95 degrees or less. When the structures 13 are cut in the X-axis direction, which is perpendicular to the Y-axis direction (i.e., the ridgeline direction of the structures 13), the cut surface has an approximately fan shape.

[0036] The structure 13 is preferably transparent. The transparency is preferably in the near-infrared region and the visible region. Since the structure 13 is transparent in the near-infrared region, an image can be drawn on the recording layer 12 using laser light in the near-infrared region. Furthermore, since the structure 13 is transparent in the visible region, the image drawn on the recording layer 12 can be visually recognized. The refractive index of the structure 13 is preferably 1.35 or more and 1.85 or less, more preferably 1.49 or more and 1.76 or less.

[0037] Pitch ΔD of the structures 13 in the X-axis direction X is the width W of the color-developing portion 12A in the X-axis direction from the viewpoint of the visibility of the structure 13 as a design and the ease of forming the structure 13. X Specifically, the width W of the color-producing section 12A in the X-axis direction is preferably sufficiently larger than X Pitch ΔD of the structure 13 in the X-axis direction relative to X The ratio (ΔD X / W X ) is preferably 1 or more and 10,000 or less, more preferably 100 or more and 1,000 or less.

[0038] Pitch ΔD of the structures 13 in the X-axis direction X is the pitch Δd′ of the color-developing portion 12A in the X-axis direction from the viewpoint of the visibility of the structure 13 as a design and the ease of forming the structure 13. X Specifically, the pitch Δd′ of the color forming portions 12A in the X-axis direction is preferably sufficiently larger than X Pitch ΔD of the structure 13 in the X-axis direction relative to X The ratio (ΔD X / Δd' X ) is preferably 0.5 or more and 1000 or less, and more preferably 0.8 or more and 900 or less.

[0039] Width A of the structure 13 in the X-axis direction X is the width W of the color-developing portion 12A in the X-axis direction from the viewpoint of the visibility of the structure 13 as a design and the ease of forming the structure 13. XSpecifically, the width W of the color-producing section 12A in the X-axis direction is preferably sufficiently larger than X Width A of the structure 13 in the X-axis direction X The ratio (A X / W X ) is preferably 1 or more and 10,000 or less, more preferably 100 or more and 1,000 or less.

[0040] The width W of the color-forming portion 12A in the X-axis direction X From the viewpoint of improving resolution, the pitch Δd′ of the color-forming portions 12A in the X-axis direction is preferably 10 μm or more and 100 μm or less. X From the viewpoint of improving the resolution, the pitch ΔD of the structures 13 in the X-axis direction is preferably 10 μm or more and 100 μm or less. X The width A of the structure 13 in the X-axis direction is preferably 0.1 mm or more and 10,000 mm or less, and more preferably 1 mm or more and 10,000 mm or less. X is preferably 0.1 mm or more and 10,000 mm or less, and more preferably 1 mm or more and 10,000 mm or less.

[0041] Position P on the surface of the structure 13 n,m and the maximum value of the distance l of the color-forming portion 12A is l max Then, from the viewpoint of the visibility of the structure 13 as a design and the ease of forming the structure 13, ma x is preferably sufficiently larger than the wavelength of visible light. Specifically, it is preferably 0.1 mm or more and 10,000 mm or less, and more preferably 1 mm or more and 1,000 mm or less. n,m and the minimum value of the distance l of the color-forming portion 12A is l min Then, l max and min The difference (l max -l min ) is, for example, 0.1 mm or more and 10,000 mm or less.

[0042] The structure 13 includes, for example, a polymer resin, glass, or a composite thereof. The polymer resin may be, for example, at least one resin material selected from the group consisting of thermoplastic resin, thermosetting resin, and ultraviolet-curable resin. Specific examples of the polymer resin include at least one selected from the group consisting of triacetyl cellulose (TAC), polyester (TPEE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polyamide (PA), aramid, polyethylene (PE), polyacrylate, polyethersulfone, polysulfone, polypropylene (PP), diacetyl cellulose, polyvinyl chloride, acrylic resin (PMMA), polycarbonate (PC), epoxy resin, urea resin, urethane resin, melamine resin, and cycloolefin polymer (COP). Examples of the glass include at least one selected from the group consisting of quartz, sapphire, and glass.

[0043] (middle class) The intermediate layer 13A is provided between the plurality of structures 13 and the recording layer 12. The intermediate layer 13A may be integrally formed with the structures 13 on the bottom side of the structures 13. The intermediate layer 13A is preferably transparent. The transparency is preferably transparent to the near-infrared region and the visible region. The intermediate layer 13A may be made of the same material as the structures 13, or may be made of a different material from the structures 13.

[0044] [Method of manufacturing recording medium] The recording medium 10 according to the first embodiment can be manufactured using, for example, a coating method. Note that the manufacturing method described below is an example, and other methods may also be used for manufacturing.

[0045] First, a polymer material is dissolved in a solvent (e.g., methyl ethyl ketone). Next, a color-developing compound, an electron-accepting substance, and a photothermal conversion material are added to this solution and dispersed. This results in a coating material for forming a recording layer. Next, this coating material for forming a recording layer is applied to a support substrate 11 to a thickness of, for example, 3 μm, and dried at, for example, 70°C to form a recording layer 12. Next, a resin is applied to the recording layer 12, and the resin is hardened while a mold is pressed against the resin, thereby forming a plurality of structures 13. This results in a recording medium 10 shown in FIG. 1.

[0046] The recording layer 12 may be formed by a method other than the above coating method. For example, the recording layer 12 may be formed by applying a layer to a different substrate in advance and then attaching the layer to the support substrate 11 via an adhesive layer, for example. Alternatively, the recording layer 12 may be formed by immersing the support substrate 11 in a coating material.

[0047] [How to set drawing parameters] position P n,m , P n+1,m Refraction angle θ' at n,m , θ' n+1,m The difference Δθ'=|θ' n+1,m -θ' n,m The color-producing sections 12A adjacent to each other in the X-axis direction are likely to overlap with each other when drawing, in the area where the refraction angle θ' n,m , θ' n+1,m In the part where the difference Δθ' is the largest, Δd' X >W X If the relationship is satisfied, Δd' is also satisfied in other parts. X >W X Therefore, the refraction angle θ' n,m , θ' n+1,m In the part where the difference Δθ' is the largest, Δd' X >W X If you set the drawing parameters so that the relationship between Δd' is satisfied, X >W X The image can be drawn so as to satisfy the relationship:

[0048] Specifically, the parameters for drawing are set as follows: First, detailed shape information of the entire structure 13 is acquired using a 3D scanning device or the like. Next, using the acquired shape information, a refraction angle θ′ on the first surface (curved surface) S1 of the structure 13 is calculated. n,m , θ' n+ 1,m The difference Δθ'=|θ' n+1,m -θ' n,m Identify the position where | is greatest.

[0049] Next, using the acquired shape information, the distance l and the incident angle θ at the specific position are calculated. n+1 ,m , θ n,m Next, the refractive index n of the structure 13 is calculated using, for example, an Abbe refractometer. Note that the constituent material of the structure 13 may be identified by instrumental analysis or the like, and a representative refractive index n of the constituent material may be used. Here, the refractive index is the refractive index for the laser light L used for drawing.

[0050] Next, the distance l and the incident angle θ obtained as described above are n+1,m , θ n,m and refractive index n, Δd' at the above specific position X >W X Δd so that X The value of is calculated from the formula (2b). X is set to a predetermined value (for example, 50 μm) depending on the spot diameter of the laser light L. Also, the width W of the color-producing portion 12A X is almost constant regardless of the position in the X-axis direction.

[0051] [Drawing method] In the recording medium 10 according to the first embodiment, for example, an image can be written on the recording layer 12 via the structures 13 in the following manner.

[0052] First, the recording layer 12 is heated to a temperature at which the color former compound is decolorized, for example, 120°C, to preliminarily decolorize it. Next, near-infrared light (external stimulus) with an adjusted wavelength and output is irradiated to a desired position on the recording layer 12 via the structure 13, for example, using a semiconductor laser. This causes the photothermal conversion material contained in the recording layer 12 to generate heat, causing a color reaction (color-developing reaction) between the color former compound and the electron-accepting substance, causing the irradiated portion to develop color, forming the color-developing portion 12A.

[0053] On the other hand, when decoloring the colored portion, near-infrared rays are irradiated through the structure 13 with energy sufficient to reach the decolorization temperature. This causes the photothermal conversion material contained in the recording layer 12 to generate heat, causing a decolorization reaction between the color former and the electron acceptor, causing the color of the irradiated portion to disappear and erasing the recording. When erasing all of the recordings formed in the recording layer 12 at once, the recording medium 10 is heated to a temperature sufficient to decolorize the recording layer 12, for example, 120°C. This erases all of the information recorded in the recording layer 12 at once. Thereafter, by performing the above-mentioned operation, repeated recording to the recording layer 12 becomes possible.

[0054] The colored and decolored states are maintained unless the coloring and decoloring reactions such as irradiation with near-infrared rays or heating are carried out.

[0055] [Action and effect] In the recording medium 10 according to the first embodiment, the pitch Δd′ of the color-forming portions 12A in the X-axis direction X and the width W of the color-forming portion 12A in the X-axis direction X and Δd' X >W X This satisfies the relationship shown in FIG. 1. As a result, even if the first surface S1 of the structure 13 is a convex curved surface such as an arch shape, it is possible to prevent the color-producing portions 12A adjacent to each other in the X-axis direction from overlapping with each other. Therefore, even if the first surface S1 of the structure 13 is a convex curved surface such as an arch shape, it is possible to prevent the color density from deviating from the desired color density. Furthermore, by providing structures 13, i.e., unevenness, on the surface of recording medium 10, it is possible to improve the design of exterior members, electronic devices, etc. to which recording medium 10 is applied. Furthermore, the surfaces of exterior members, electronic devices, etc. to which recording medium 10 is applied become less slippery. Furthermore, since the recording layer 12 can be written by irradiating the surface of the structures 13 with laser light, there is no need to perform a process that distorts the normal image. Furthermore, since there is no need to align the multiple structures 13 and the recording layer 12 after writing, the recording medium 10 can be easily produced.

[0056] <2. Second embodiment> [Storage medium configuration] Fig. 4 is a perspective view showing an example of the configuration of a recording medium 20 according to the second embodiment. Fig. 5 is a cross-sectional view taken along line VV in Fig. 4. The recording medium 20 differs from the recording medium 10 according to the first embodiment in that it includes a recording layer 22 and a structure 23 instead of the recording layer 12 and the structure 13 (see Figs. 1, 2A, and 2B).

[0057] (recording layer) The recording layer 22 has a pitch Δd′ of the color-producing portions 12A in the X-axis direction, excluding the boundary between adjacent structures 23. X However, it differs from the recording layer 12 in the first embodiment in that it is constant in the X-axis direction.

[0058] (structure) Structure 23 differs from structure 13 in the first embodiment in that first surface S1 is a plane inclined with respect to the surface of recording layer 12. When structure 13 is cut in the X-axis direction perpendicular to the Y-axis direction (i.e., the ridge direction of structure 13), the cut surface has a substantially right-angled triangular shape.

[0059] 4 shows an example in which the first surface S1 and the second surface S2 face each other between adjacent structures 13, but the orientation of the first surface S1 and the second surface S2 is not limited to this. For example, the first surfaces S1 may face each other between adjacent structures 13, or the second surfaces S2 may face each other between adjacent structures 13.

[0060] [Action and effect] In the recording medium 20 according to the second embodiment, the pitch Δd′ of the color-producing portions 12A is 0.05 mm, except for the boundary between adjacent structures 23. X Since is constant, the display quality of the image can be improved.

[0061] <3 Third embodiment> [Storage medium configuration] FIG. 6A is a perspective view showing an example of the configuration of a recording medium 30 according to the third embodiment. FIG. 6B is a plan view showing an example of the configuration of a recording medium 20 according to the third embodiment. FIG. 7A is a cross-sectional view taken along line VIIA-VIIA in FIG. 6B. FIG. 7B is a cross-sectional view taken along line VIIB-VIIB in FIG. 6B. The recording medium 30 differs from the recording medium 10 according to the first embodiment in that it includes a recording layer 32 and a structure 33 instead of the recording layer 12 and the structure 13 (see FIGS. 1, 2A, and 2B).

[0062] (recording layer) Pitch Δd′ of the color-producing portion 12A in the X-axis direction X and the width W of the color-forming portion 12A in the X-axis direction X and Δd' X >W X This satisfies the relationship shown in FIG. 1. This makes it possible to prevent adjacent color producing sections 12A from overlapping with each other in the X-axis direction. Therefore, it is possible to prevent the color density from deviating from the desired color density in the areas where the color producing sections 12A overlap with each other in the X-axis direction.

[0063] Pitch Δd′ of the color-forming portion 12A in the Y-axis direction Y and the width W of the color-forming portion 12A in the Y-axis direction Y and Δd' Y >W Y This satisfies the relationship shown in FIG. 1. This makes it possible to prevent adjacent color producing sections 12A from overlapping with each other in the Y-axis direction. Therefore, it is possible to prevent the color density from deviating from the desired color density in the areas where the color producing sections 12A overlap with each other in the Y-axis direction.

[0064] Pitch Δd′ of the color-producing portion 12A in the X-axis direction X 7A, changes in the X-axis direction (in-plane direction of the recording layer 32). More specifically, when the position P n,m The light L incident on the color-producing section 12A reaches the position P' n, m If we reach position P', n,m The pitch Δd' of the color-forming portion 12A in X is the position P n,m The surface inclination α of the structure 33 at X However, the steeper the position P n,m indicates the position of the surface of the structure 33 in the in-plane direction of the recording layer 32. Also, the inclination α X indicates the tilt in the X-axis direction, that is, the tilt in the XZ cross section of the structure 33.

[0065] Pitch Δd′ of the color-forming portion 12A in the Y-axis direction Y 7B, the direction of the structure 33 changes in the Y-axis direction (the in-plane direction of the recording layer 32). More specifically, the direction of the structure 33 changes from the direction perpendicular to the recording layer 32 to the position P n,m The light L incident on the color-producing section 12A reaches the position P' n, m If we reach position P', n,m The pitch Δd' of the color-forming portion 12A in Y is the position P n,m The surface inclination α of the structure 33 at Y However, the steeper the slope, the narrower the Y indicates the tilt in the Y-axis direction, that is, the tilt in the YZ cross section of the structure 33.

[0066] As mentioned above, the pitch Δd' X changes in the X-axis direction, and the pitch Δd' Ychanges in the Y-axis direction, so when the image drawn on the recording layer 32 is viewed from the Z-axis direction through the structures 13, it becomes an image that is not distorted in the X-axis and Y-axis directions (hereinafter referred to as a "normal image"). In contrast, when the image drawn on the recording layer 32 is viewed from the Z-axis direction with the structures 13 removed, it becomes an image that is distorted in the X-axis and Y-axis directions compared to the normal image.

[0067] In all other respects, the recording layer 32 is similar to the recording layer 12 in the first embodiment.

[0068] (structure) The structures 33 are two-dimensionally arranged in a regular predetermined arrangement pattern. A plurality of structures 21 are arranged, for example, in a plurality of rows on the surface of the support base 11. The surface of the structures 21 is a convex curved surface that curves in both the X-axis direction and the Y-axis direction. The structures 21 have, for example, an approximately hemispherical shape.

[0069] Pitch ΔD of the structures 33 in the X-axis direction X is the width W of the color-developing portion 12A in the X-axis direction from the viewpoint of the visibility of the structure 33 as a design and the ease of forming the structure 33. X Specifically, the width W of the color-producing section 12A in the X-axis direction is preferably sufficiently larger than X Pitch ΔD of the structure 33 in the X-axis direction with respect to X The ratio (ΔD X / W X ) is preferably 1 or more and 10,000 or less, more preferably 100 or more and 1,000 or less.

[0070] Pitch ΔD of the structures 33 in the Y-axis direction Y is the width W of the color-developing portion 12A in the Y-axis direction from the viewpoint of the visibility of the structure 33 as a design and the ease of forming the structure 33. Y Specifically, the width W of the color-producing section 12A in the Y-axis direction is preferably sufficiently larger than Y Pitch ΔD of the structure 33 in the Y-axis direction relative to Y The ratio (ΔD Y / WY ) is preferably 1 or more and 10,000 or less, more preferably 100 or more and 1,000 or less.

[0071] Pitch ΔD of the structures 33 in the X-axis direction X is the pitch Δd′ of the color-developing portion 12A in the X-axis direction from the viewpoint of the visibility of the structure 33 as a design and the ease of forming the structure 33. X Specifically, the pitch Δd′ of the color forming portions 12A in the X-axis direction is preferably sufficiently larger than X Pitch ΔD of the structure 33 in the X-axis direction with respect to X The ratio (ΔD X / Δd' X ) is preferably 0.5 or more and 1000 or less, and more preferably 0.8 or more and 900 or less.

[0072] Pitch ΔD of the structures 33 in the Y-axis direction Y is the pitch Δd′ of the color-developing portion 12A in the Y-axis direction from the viewpoint of the visibility of the structure 33 as a design and the ease of forming the structure 33. Y Specifically, the pitch Δd′ of the color forming portions 12A in the Y-axis direction is preferably sufficiently larger than Y Pitch ΔD of the structure 33 in the Y-axis direction relative to Y The ratio (ΔD Y / Δd' Y ) is preferably 0.5 or more and 1000 or less, and more preferably 0.8 or more and 900 or less.

[0073] Width A of the structure 33 in the X-axis direction X is the width W of the color-developing portion 12A in the X-axis direction from the viewpoint of the visibility of the structure 33 as a design and the ease of forming the structure 33. X Specifically, the width W of the color-producing section 12A in the X-axis direction is preferably sufficiently larger than X Width A of the structure 33 in the X-axis direction X The ratio (A X / W X ) is preferably 1 or more and 10,000 or less, more preferably 100 or more and 1,000 or less.

[0074] Width A of the structure 33 in the Y-axis direction Y is the width W of the color-developing portion 12A in the Y-axis direction from the viewpoint of the visibility of the structure 33 as a design and the ease of forming the structure 33. Y Specifically, the width W of the color-producing section 12A in the Y-axis direction is preferably sufficiently larger than Y Width A of the structure 33 in the Y-axis direction Y The ratio (A Y / W Y ) is preferably 1 or more and 10,000 or less, more preferably 100 or more and 1,000 or less.

[0075] The width W of the color-forming portion 12A in the X-axis direction X From the viewpoint of improving resolution, the pitch Δd′ of the color-forming portions 12A in the X-axis direction is preferably 10 μm or more and 100 μm or less. X From the viewpoint of improving color density, the pitch ΔD of the structures 33 in the X-axis direction is preferably 10 μm or more and 100 μm or less. X The width A of the structure 33 in the X-axis direction is preferably 0.1 mm or more and 10,000 mm or less, and more preferably 1 mm or more and 1,000 mm or less. X is preferably 0.1 mm or more and 10,000 mm or less, and more preferably 1 mm or more and 1,000 mm or less.

[0076] The width W of the color-producing portion 12A in the Y-axis direction Y From the viewpoint of improving resolution, the pitch Δd′ of the color-forming portions 12A in the Y-axis direction is preferably 10 μm or more and 100 μm or less. X From the viewpoint of improving color density, the pitch ΔD of the structures 33 in the Y-axis direction is preferably 10 μm or more and 100 μm or less. Y The width A of the structure 33 in the Y-axis direction is preferably 0.1 mm or more and 10,000 mm or less, and more preferably 1 mm or more and 1,000 mm or less. Y is preferably 0.1 mm or more and 10,000 mm or less, and more preferably 1 mm or more and 1,000 mm or less.

[0077] In all other respects, the structure 33 is similar to the structure 13 in the first embodiment.

[0078] [Action and effect] In the recording medium 30 according to the third embodiment, the pitch Δd′ of the color-forming portions 12A in the X-axis direction X and the width W of the color-forming portion 12A in the X-axis direction X and Δd' X >W X and the pitch Δd′ of the color-forming portions 12A in the Y-axis direction is Y and the width W of the color-forming portion 12A in the Y-axis direction Y and Δd' Y >W Y This satisfies the relationship shown in Fig. 1. As a result, even when the structures 13 have a curved shape such as an approximately hemispherical shape, it is possible to prevent the color-producing portions 12A adjacent to each other in the X-axis direction and the color-producing portions 12A adjacent to each other in the Y-axis direction from overlapping with each other. Therefore, even when the structures 13 have a curved shape such as an approximately hemispherical shape, it is possible to prevent the color density from deviating from the desired color density.

[0079] <4. Fourth embodiment> [Storage medium configuration] 8A is a cross-sectional view showing an example of the configuration of a recording medium 40 according to the fourth embodiment. The recording medium 40 differs from the recording medium 10 according to the first embodiment in that it includes a multi-layered recording layer 42 that displays a multi-color (e.g., full-color) image, instead of the single-layered recording layer 12 (see FIGS. 1, 2A, and 2B) that displays a single-color image.

[0080] The recording layer 42 includes a first layer 421, a second layer 422, a third layer 423, a heat insulating layer 424, and a heat insulating layer 425. The second layer 422 is provided on the first layer 421, and the third layer 423 is provided on the second layer 422. The heat insulating layer 424 is provided between the first layer 421 and the second layer 422, and the heat insulating layer 425 is provided between the second layer 422 and the third layer 423.

[0081] The first layer 421, the second layer 422, and the third layer 423 contain pigments that exhibit different colors, and an image is formed by the pigments contained in these layers. The first layer 421 contains, for example, a pigment that produces yellow color. The second layer 422 contains, for example, a pigment that produces cyan color. The third layer 423 contains, for example, a pigment that produces magenta color.

[0082] The first layer 421 has, for example, a coloring portion 421A containing a pigment in a colored state and a non-coloring portion 421B containing a color in a decolored state. The second layer 422 has, for example, a coloring portion 422A containing a pigment in a colored state and a non-coloring portion 422B containing a color in a decolored state. The third layer 423 has, for example, a coloring portion 423A containing a pigment in a colored state and a non-coloring portion 423B containing a color in a decolored state. The non-coloring portion 421B, the non-coloring portion 422B, and the non-coloring portion 423B are, for example, transparent.

[0083] In FIG. 8A, the color forming portion 421A, the color forming portion 422A, and the color forming portion 423A are all positioned P'. n,m 8A shows an example in which color-forming sections 421A, 422A, and 423A are arranged so as to overlap, but the arrangement of color-forming section 421A, color-forming section 422A, and color-forming section 423A is selected according to the image to be drawn on recording layer 42, and is not limited to the arrangement example shown in FIG.

[0084] The first layer 421, the second layer 422, and the third layer 423 are preferably each made of a material that allows stable recording and that can control the color development state. Specifically, the first layer 421, the second layer 422, and the third layer 423 each contain, for example, color-developing compounds that produce different color hues and electron-accepting substances that correspond to the color-developing compounds. The first layer 421, the second layer 422, and the third layer 423 preferably contain a photothermal conversion material or a polymer resin that absorbs light in different wavelength ranges and generates heat, and more preferably contain both of these materials.

[0085] As described above, the electron-accepting substance is used, for example, to color a colorless color former or to reduce the color of a color former exhibiting a predetermined color. The electron-accepting substance is selected from compounds having a salicylic acid skeleton as shown in the above formula (2) and containing an electron-accepting group in the molecule. As described above, the photothermal conversion material is selected from compounds having a phthalocyanine skeleton (phthalocyanine dyes), compounds having a squarylium skeleton (squaryllium dyes), inorganic compounds, etc. In addition, as in the first embodiment, compounds having a cyanine skeleton (cyanine dyes) with excellent light resistance and heat resistance may also be used.

[0086] Specifically, the first layer 421 contains, for example, a color-forming compound that produces yellow in its color-forming state, a corresponding electron-accepting substance, a photothermal conversion material that absorbs infrared light of wavelength λ1 to generate heat, and a polymer resin. The second layer 422 contains, for example, a color-forming compound that produces cyan in its color-forming state, a corresponding electron-accepting substance, a photothermal conversion material that absorbs infrared light of wavelength λ2 to generate heat, and a polymer resin. The third layer 423 contains, for example, a color-forming compound that produces magenta in its color-forming state, a corresponding electron-accepting substance, a photothermal conversion material that absorbs infrared light of wavelength λ3 to generate heat, and a polymer resin. This results in a recording layer 42 capable of displaying multiple colors.

[0087] It is preferable to select a combination of photothermal conversion materials that have narrow light absorption bands, for example, in the wavelength range of 700 nm to 2000 nm, and that do not overlap with each other, thereby making it possible to selectively color or reduce the color of a desired layer among the first layer 421, the second layer 422, and the third layer 423.

[0088] The thickness of each of the first layer 421, the second layer 422, and the third layer 423 is preferably, for example, 1 μm or more and 20 μm or less, and more preferably, for example, 2 μm or more and 15 μm or less. If the thickness of each of the first layer 421, the second layer 422, and the third layer 423 is less than 1 μm, sufficient color density may not be obtained. If the thickness of each of the first layer 421, the second layer 422, and the third layer 423 exceeds 20 μm, the amount of heat used by each of the first layer 421, the second layer 422, and the third layer 423 increases, and color development may be impaired.

[0089] Similarly to the recording layer 12, the first layer 421, the second layer 422 and the third layer 423 may contain various additives such as a sensitizer and an ultraviolet absorbing material in addition to the above materials.

[0090] The heat insulating layer 424 provides thermal insulation between the first layer 421 and the second layer 422. The heat insulating layer 425 provides thermal insulation between the second layer 422 and the third layer 423. The heat insulating layer 424 and the heat insulating layer 425 are transparent. Specifically, for example, the heat insulating layer 424 and the heat insulating layer 425 are transparent in the near-infrared region and the visible region.

[0091] Heat insulating layer 424 and heat insulating layer 425 include, for example, a general light-transmitting polymer material. Specific materials for heat insulating layer 424 and heat insulating layer 425 include at least one selected from the group consisting of polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethyl cellulose, polystyrene, styrene copolymer, phenoxy resin, polyester, aromatic polyester, polyurethane, polycarbonate, polyacrylic acid ester, polymethacrylic acid ester, acrylic acid copolymer, maleic acid polymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, and starch. Heat insulating layer 424 and heat insulating layer 425 may also include various additives, such as ultraviolet absorbers.

[0092] The heat insulating layers 424 and 425 may contain a translucent inorganic material. For example, if the heat insulating layers 424 and 425 contain porous silica, alumina, titania, carbon, or a composite of these, the thermal conductivity will be low and the heat insulating effect will be high, which is preferable. The heat insulating layers 424 and 425 can be formed by, for example, a sol-gel method.

[0093] The thickness of the heat insulating layers 424 and 425 is preferably, for example, 3 to 100 μm, and more preferably, for example, 5 to 50 μm. If the thickness of the heat insulating layers 424 and 425 is too thin, a sufficient heat insulating effect cannot be obtained, and if the thickness is too thick, the thermal conductivity deteriorates when the entire recording layer 42 is heated uniformly, and the light transmittance decreases.

[0094] In all other respects, the first layer 421, the second layer 422 and the third layer 423 are similar to the recording layer 12 in the first embodiment.

[0095] [Principle of multi-color display] The principle of multi-color display will be explained using an example in which the first layer 421, the second layer 422, and the third layer 423 contain a dye that produces yellow, a dye that produces cyan, and a dye that produces magenta, respectively.

[0096] For example, a green colored portion is formed by a portion where a yellow colored portion 421A, a cyan colored portion 422A, and a non-colored portion 423B overlap in the thickness direction of the recording layer 42. For example, a red colored portion is formed by a portion where a yellow colored portion 421A, a cyan colored portion 422A, and a magenta colored portion 422A overlap in the thickness direction of the recording layer 42.

[0097] [Action and effect] As described above, the recording medium 40 according to the fourth embodiment includes a first layer 421, a second layer 422, and a third layer 423. The first layer 421, the second layer 422, and the third layer 423 contain dyes that exhibit different colors, and an image is formed by the dyes contained in each of these layers. This makes it possible to display a multicolor (e.g., full-color) image.

[0098] Furthermore, the pitch Δd′ between the coloring portion 421A, the coloring portion 422A, and the coloring portion 423A in the X-axis direction X and the width W of the coloring portion 421A, the coloring portion 422A, and the coloring portion 423A in the X-axis direction. X and Δd' X >W X This satisfies the relationship shown in FIG. 1. Even if the first surface S1 of the structure 13 is a convex curved surface such as an arched shape, it is possible to prevent the color producing portions 421A, 422A, and 423A adjacent to each other in the X-axis direction from overlapping with each other. Therefore, even if the first surface S1 of the structure 13 is a convex curved surface such as an arched shape, it is possible to prevent the color density from deviating from the desired color density.

[0099] Also, as mentioned above, the pitch Δd' X and width W X is Δd' X >W X Since the relationship above is satisfied, even if the first surface S1 of the structure 13 is a convex curved surface such as an arch shape, it is possible to prevent at least two of the color forming portion 421A, the color forming portion 422A, and the color forming portion 423A from unintentionally overlapping with each other in the thickness direction (Z-axis direction) of the recording layer 42. Therefore, even if the first surface S1 of the structure 13 is a convex curved surface such as an arch shape, it is possible to prevent deviation from the desired hue.

[0100] 8B is a cross-sectional view showing the structure of the recording layer 43 as a reference example. In the recording layer 43, the pitch Δd′ X and width W X is Δd' X >W XSince the relationship above is not satisfied, color forming portion 421A, color forming portion 422A, and color forming portion 423A unintentionally overlap in the thickness direction (Z-axis direction) of recording layer 42 (see the area indicated by region R1 in FIG. 8B). In this way, a deviation from the desired hue occurs in the area where color forming portion 421A, color forming portion 422A, and color forming portion 423A overlap. Note that a deviation from the desired hue also occurs when two of color forming portion 421A, color forming portion 422A, and color forming portion 423A unintentionally overlap in the thickness direction (Z-axis direction) of recording layer 42, as indicated by regions R2 and R3 in FIG. 8B.

[0101] <5. Fifth embodiment> [Storage medium configuration] 9 is a cross-sectional view showing an example of the configuration of a recording medium 50 according to the fifth embodiment. The recording medium 50 differs from the recording medium 40 according to the fourth embodiment in that the recording medium 50 includes a single-layer recording layer 52 that displays a multi-color (e.g., full-color) image, instead of the three-layer recording layer 42 (see FIG. 8) that displays a multi-color (e.g., full-color) image.

[0102] The recording layer 52 includes three types of microcapsules 51C, 51M, and 51Y, each with a different color hue, and a polymer resin. An image is formed by these three types of microcapsules 51C, 51M, and 51Y. Each of the microcapsules 51C, 51M, and 51Y includes, for example, a color former that exhibits a different color (e.g., cyan (C), magenta (M), and yellow (Y)), an electron acceptor corresponding to each color former, a photothermal conversion material that absorbs light in different wavelength ranges and generates heat, and a capsule wall. The color former, electron acceptor, and photothermal conversion material are contained within the capsule wall. The capsule wall is preferably made of the same material as that used for the heat insulating layers 424 and 425 in the fourth embodiment.

[0103] In all other respects, the recording layer 52 is similar to the recording layer 12 in the first embodiment.

[0104] [Action and effect] As described above, in the recording medium 50 according to the fifth embodiment, the recording layer 52 contains three types of microcapsules 51C, 51M, and 51Y, each of which exhibits a different color when colored, and a polymer resin. An image is formed by these three types of microcapsules 51C, 51M, and 51Y (specifically, the color-forming compounds contained in each of these three types of microcapsules 51C, 51M, and 51Y). This allows a multicolor (e.g., full-color) image to be displayed on the single-layer recording layer 52.

[0105] <6 Variations> (Variation 1) In the first and second embodiments, examples have been described in which the cut surfaces of the structures 13, 23 perpendicular to the X-axis direction (i.e., the ridge line direction of the structures 13, 23) have a substantially fan shape or a substantially right-angled triangle shape, but the shapes of the cut surfaces of the structures 13, 23 are not limited to this. For example, the shapes of the cut surfaces of the structures 13, 23 may be substantially parabolic (see FIG. 10A), equilateral triangular (see FIG. 10B), isosceles triangular, trapezoidal (see FIG. 10C), wavy (see FIG. 10D), substantially circular arc, substantially elliptical arc, or the like. It should be noted that there are places where the laser light is incident at a right angle without being refracted, such as the ridges of the structures 13 and 23. In such cases, it may be difficult to avoid intersecting with adjacent drawing lines, but since the ridges of the structures 13 and 23 overlap with these places, it can be determined that there is almost no effect on visibility.

[0106] (Variation 2) In the third embodiment, an example has been described in which the two-dimensionally arranged structures 33 have an approximately hemispherical shape, but the shape of the structures 33 is not limited thereto. For example, the structures 33 may be conical, columnar, needle-like, semi-ellipsoidal, polygonal, or the like. Examples of conical shapes include, but are not limited to, a conical shape with a pointed apex, a conical shape with a flat apex, and a conical shape with a convex or concave curved apex. Examples of conical shapes with a convex curved apex include quadratic curved surfaces such as a paraboloid. The conical surface of the conical shape may be curved concavely or convexly. Examples of polygonal shapes include a cube or a rectangular parallelepiped. The structures may have a two-dimensional regular pattern (e.g., a geometric pattern) or a two-dimensional random pattern. Note that there are places where the laser light is incident at a right angle without being refracted, such as the vertices of each structure 33. In such cases, it may be difficult to avoid intersecting with adjacent drawing lines, but since these overlap with the vertices of the structures 33 themselves, it can be determined that there is almost no effect on visibility.

[0107] (Variation 3) In the first to fifth embodiments, examples have been described in which structures 13, 23, and 33 having the same shape are arrayed one-dimensionally or two-dimensionally, but the shapes of the one-dimensionally or two-dimensionally arrayed structures 13, 23, and 33 are not limited to one type. For example, as shown in Fig. 11A, two or more types of structures 13, 23, and 33 having different shapes may be arrayed one-dimensionally or two-dimensionally.

[0108] (Variation 4) In the first to fifth embodiments, examples have been described in which the plurality of structures 13, 23, and 33 are arranged regularly, but the plurality of structures 13, 23, and 33 may also be arranged randomly.

[0109] (Variation 5) In the first to fifth embodiments, examples have been described in which adjacent structures 13, 23, and 33 are densely arranged with no space between them, but as shown in FIG. 11B, spaces may be provided between adjacent structures 13, 23, and 33.

[0110] (Variation 6) In the first and second embodiments, examples have been described in which the ridges and corners of the structures 13 and 23 are sharp, but the ridges and corners may be rounded. For example, as shown in Fig. 11C, the shape of the cut surface of the structures 13 and 23 may be a trapezoid with rounded corners.

[0111] (Variation 7) In the first embodiment, an example has been described in which the structure 13 or intermediate layer 13A is provided directly on the recording layer 12. However, as shown in FIG. 12A , an adhesive layer 14 may be provided between the recording layer 12 and the structure 13 or intermediate layer 13A. In this specification, pressure-sensitive adhesion is defined as a type of adhesion. According to this definition, an adhesive layer is considered to be a type of adhesive layer 14.

[0112] Similarly, in the second to fifth embodiments, an adhesive layer 14 may be provided between the recording layer 12, 22, 32, 42, 52 and the structures 13, 23, 33.

[0113] (Variation 8) In the first embodiment, an example has been described in which the recording layer 12 is provided directly on the support base 11, but as shown in Fig. 12B, an adhesive layer 15 may be provided between the support base 11 and the recording layer 12. In this case, as shown in Fig. 12C, an adhesive layer 14 may further be provided between the recording layer 12 and the structure 13 or the intermediate layer 13A.

[0114] Similarly, in the second to fifth embodiments, an adhesive layer 15 may be provided between the support substrate 11 and the recording layer 12, 22, 32, 42, or 52. In this case, an adhesive layer 14 may further be provided between the recording layer 12, 22, 32, 42, or 52 and the structure 13, 23, or 33.

[0115] (Variation 9) In the first to fifth embodiments, examples have been described in which the recording media 10, 20, 30, 40, and 50 are provided with a support base 11, but if the structure 13, 23, and 33 or the intermediate layer 13A is configured to be able to support the recording layer 12, 22, 32, 42, and 52, the support base 11 may not be provided.

[0116] (Variation 10) In the fourth embodiment, an example has been described in which the recording layer 42 includes three layers, the first to third layers 421 to 423, each containing a color former that differs from one another in color-developing hues. However, the recording layer 42 may also include a first layer to an n-th layer (where n is an integer of 2 or more) each containing a color former that differs from one another in color-developing hues. In this case, each of the first layer to the n-th layer may have a plurality of color-developing portions. Furthermore, a heat-insulating layer may be provided between each of the first layer to the n-th layer.

[0117] <7 Application Examples> Next, application examples of the recording media 10, 20, 30, 40, and 50 (hereinafter referred to as "recording media 10, etc.") described in the first to fifth embodiments and modifications will be described. However, the application examples described below are merely examples, and their configurations can be modified as appropriate. The recording media 10, etc. can be applied to various electronic devices or parts of clothing accessories, such as so-called wearable terminals, such as watches (wristwatches), bags, clothes, hats, glasses, and shoes, and the type of electronic device, etc., is not particularly limited. Furthermore, the recording media can be applied not only to electronic devices and clothing accessories, but also, for example, as exterior components for the interior and exterior of building walls, the exterior of furniture such as desks, etc.

[0118] (Example 1) FIG. 13A shows the external configuration of the front of a smartphone 60, and FIG. 13B shows the external configuration of the back of the smartphone 60 shown in FIG. 13A. The smartphone 60 includes, for example, a display unit 61, a non-display unit 62, and a housing 63. A recording medium 64, for example, is provided on, for example, one surface of the rear side of the housing 63 as an exterior member of the housing 63, thereby allowing various colors and patterns to be displayed. The recording medium 64 is any of the recording media 10, etc. Two or more of the recording media 10, etc. may be used in combination. FIG. 13B shows an example in which the recording medium 10 (see FIG. 1) is used as the recording medium 64. Note that, while a smartphone 60 is given as an example here, the present invention is not limited to this, and can also be applied to, for example, a notebook personal computer (PC), a tablet PC, etc.

[0119] When an image is drawn on the recording medium 64 , the recording layer 12 is irradiated with laser light through the structures 13 .

[0120] (Example 2) FIG. 14 is a perspective view showing an example of the appearance of a nail tip 70. The nail tip 70 is an example of an exterior member. The nail tip 70 includes a recording medium 71. The recording medium 71 is similar to the recording medium 30 in the third embodiment, except that it has a curved surface and that a plurality of structures 33 are provided in a partial area on the recording layer 32. Although not shown in FIG. 14, color-forming portions 12A, such as stripes, are also formed below the structures 33.

[0121] 14 is just an example, and the shape, size, arrangement, arrangement area, etc. of the structure 33 can be changed according to the design of the nail tip 70. Similarly, the shape, size, arrangement, arrangement area, etc. of the coloring portion 12A and the non-coloring portion 12B can also be changed according to the design of the nail tip 70.

[0122] When an image is drawn on the recording medium 71 , the recording layer 32 is irradiated with laser light through the structures 33 .

[0123] (Example 3) FIG. 15A is a plan view showing an example of the appearance of a nail sticker 80. FIG. 15B is a cross-sectional view taken along line XVB-XVB in FIG. 15A. The nail sticker 80 is an example of an exterior member. The nail sticker 80 includes a release sheet 83 and a recording medium 81. The recording medium 81 includes an adhesive layer 81A on the back surface of a support base 11. The recording medium 81 includes multiple nail sticker portions 82 to be attached to the nails of each finger on both hands. The nail sticker portions 82 are held in a cut or semi-cut state on the nail sticker 80 and are configured to be peelable at the interface between the adhesive layer 81A and the release sheet 83. The structure 33 is provided in a partial area of ​​the nail sticker portion 82. Although not shown in FIG. 15A, a color-forming portion 12A, such as a stripe-like portion, is also formed below the structure 33. The recording medium 81 is otherwise similar to the recording medium 30 in the third embodiment.

[0124] When an image is drawn on the recording medium 81 , the recording layer 32 is irradiated with laser light via the structures 33 .

[0125] 15A and 15B are merely examples, and the shape, size, arrangement, arrangement area, etc. of the structure 33 can be changed depending on the design of the nail sticker 80. Similarly, the shape, size, arrangement, arrangement area, etc. of the coloring portion 12A and the non-coloring portion 12B can also be changed depending on the design of the nail sticker 80.

[0126] In Specific Example 2 and Specific Example 3, examples in which the present disclosure is applied to the nail tip 70 and the nail sticker 80 have been described, but application examples of the present disclosure to nails are not limited to this. For example, after the recording layer 43 and the structure 33 are directly laminated on the human nail, laser light may be irradiated onto the recording layer 32 through the structure 33 to draw an image on the recording layer 32. Furthermore, in Specific Example 2 and Specific Example 3, the recording layer 42 or the recording layer 52 may be provided instead of the recording layer 32.

[0127] The above describes the embodiments and modifications of the present disclosure in detail, but the present disclosure is not limited to the above-described embodiments and modifications, and various modifications based on the technical ideas of the present disclosure are possible.

[0128] For example, the configurations, methods, steps, shapes, materials, and numerical values, etc., given in the above-described embodiments and modifications are merely examples, and different configurations, methods, steps, shapes, materials, and numerical values, etc., may be used as necessary. The configurations, methods, steps, shapes, materials, and numerical values, etc., of the above-described embodiments and modifications can be combined with each other without departing from the spirit of the present disclosure.

[0129] In the numerical ranges described in stages in the above-mentioned embodiments and modifications, the upper or lower limit of a numerical range in a certain stage may be replaced with the upper or lower limit of a numerical range in another stage. Unless otherwise specified, the materials exemplified in the above-mentioned embodiments and modifications may be used alone or in combination of two or more.

[0130] The present disclosure may also employ the following configuration. (1) a recording layer configured so that its colored state can be changed in response to an external stimulus; a plurality of structures provided on the recording layer; Equipped with the recording layer has a plurality of color-forming portions, A recording medium in which the pitch Δd' of the color-forming portions and the width W of the color-forming portions satisfy the relationship Δd'>W. (2) 3. The recording medium according to claim 1, wherein the pitch Δd′ of the color-developing portions varies in the in-plane direction of the recording layer. (3) When light incident on a position P on the surface of the structure from a direction perpendicular to the recording layer reaches a position P' of the color-producing portion, The recording medium according to (1) or (2), wherein the pitch Δd′ of the color-developing portions at the position P′ becomes narrower as the slope of the surface of the structure at the position P becomes steeper. (4) The recording medium according to any one of (1) to (3), wherein the external stimulus is laser light. (5) The recording layer is a color former having electron donating properties; an electron accepting substance; Photothermal conversion materials The recording medium according to any one of (1) to (4), comprising: (6) The recording medium according to any one of (1) to (5), wherein the ratio (A / W) of the width A of the structure to the width W of the color-producing portion is 1 or more and 10,000 or less. (7) The recording medium according to any one of (1) to (6), wherein the width A of the structure is 0.1 mm or more and 10,000 mm or less. (8) The recording medium according to any one of (1) to (7), wherein the refractive index of the structure is 1.35 or more and 1.85 or less. (9) The recording medium according to any one of (1) to (8), further comprising an adhesive layer provided between the recording layer and the plurality of structures. (10) Further comprising a support base, The recording medium according to any one of (1) to (9), wherein the recording layer is provided on the supporting substrate. (11) The recording medium according to (10), further comprising an adhesive layer provided between the support substrate and the recording layer. (12) The recording medium according to any one of (1) to (11), wherein the structure has a curved surface. (13) the structures are pillars extending in a first direction within the plane of the recording layer, The recording medium according to (1), wherein the cut surface when the structure is cut in a second direction perpendicular to the first direction has a substantially right-angled triangular shape. (14) The recording medium according to any one of (1) to (13), wherein the plurality of structures are arranged one-dimensionally. (15) The recording medium according to any one of (1) to (12), wherein the plurality of structures are arranged two-dimensionally. (16) the recording layer includes first to n-th layers (where n is an integer of 2 or more) each containing a color former having a different color hue; The recording medium according to any one of (1) to (15), wherein the first to nth layers each have a plurality of the color-forming portions. (17) the recording layer comprises a first layer, a second layer, and a third layer; the first layer, the second layer, and the third layer contain color-forming compounds that develop color hues different from one another; The recording medium according to any one of (1) to (15), wherein the first layer, the second layer, and the third layer each have a plurality of the color-forming portions. (18) The recording medium according to any one of (1) to (15), wherein the recording layer contains three types of microcapsules that have different color hues. (19) a recording layer configured so that its colored state can be changed in response to an external stimulus; a plurality of structures provided on the recording layer; Equipped with the recording layer has a plurality of color-forming portions, A recording medium in which the pitch Δd' of the color-developing portions varies in the in-plane direction of the recording layer. (20) An exterior member comprising the recording medium according to any one of (1) to (19). [Explanation of symbols]

[0131] 10, 20, 30, 40, 50, 64, 71, 81 Recording media 11 Supporting base 12, 22, 32, 42, 43 recording layers 12A, 421A, 422A, 423A coloring section 12B, 421B, 422B, 423B Non-coloring area 13, 23, 33 structure 13A Middle layer 14, 15 Adhesive layer 51C, 51M, 51Y Microcapsules 424, 425 Insulation layer 60 Smartphones 61 Display section 62 Hidden part 63 Case 70 Nail Tips 80 Nail Stickers 82 Nail seal section 81A Adhesive layer 83 Peel-off sheet

Claims

1. A recording layer configured so that its color state can be changed by irradiation with laser light; a plurality of light-transmitting structures provided on the recording layer; Equipped with the structure includes a curved surface; the recording layer has a plurality of color-forming portions corresponding to pixels of an image, the pitch Δd′ of the color-developing portions changes in one direction, A recording medium in which a pitch Δd′ of the color-forming portions in the one direction and a width W of the color-forming portions in the one direction satisfy the relationship Δd′>W.

2. A recording layer configured so that its color state can be changed by irradiation with laser light; a plurality of light-transmitting structures provided on the recording layer; Equipped with the structure includes a plane inclined with respect to the surface of the recording layer, the recording layer has a plurality of color-forming portions corresponding to pixels of an image, the pitch Δd′ of the color-developing portions changes in one direction, A recording medium in which a pitch Δd′ of the color-forming portions in the one direction and a width W of the color-forming portions in the one direction satisfy the relationship Δd′>W.

3. When light incident on a position P on the surface of the structure from a direction perpendicular to the recording layer reaches a position P′ of the color-producing portion, 3. The recording medium according to claim 1, wherein the pitch Δd′ of the color-developing portions at the position P′ becomes narrower as the inclination of the surface of the structure at the position P becomes steeper.

4. The recording layer is a color former having electron donating properties; an electron accepting substance; Photothermal conversion materials 3. The recording medium according to claim 1, comprising:

5. A recording medium as described in claim 1 or 2, wherein the ratio (A / W) of the width A of the structure in said one direction to the width W of the color-forming portion in said one direction is greater than or equal to 1 and less than 10,000.

6. A recording medium as described in claim 1 or 2, wherein the width A of the structure in the one direction is 0.1 mm or more and 10,000 mm or less.

7. 3. The recording medium according to claim 1, wherein the refractive index of the structure is 1.35 or more and 1.85 or less.

8. The recording medium according to claim 1 , further comprising an adhesive layer provided between the recording layer and the plurality of structures.

9. Further comprising a support base, 3. The recording medium according to claim 1, wherein the recording layer is provided on the supporting substrate.

10. The recording medium according to claim 9, further comprising an adhesive layer provided between the support substrate and the recording layer.

11. the structures are columnar bodies extending in a direction perpendicular to the one direction within the plane of the recording layer, 2. The recording medium according to claim 1, wherein the cut surface when the structure is cut in the one direction has a substantially fan shape.

12. the structures are columnar bodies extending in a direction perpendicular to the one direction within the plane of the recording layer, 3. The recording medium according to claim 2, wherein the cut surface when the structure is cut in the one direction has a substantially right-angled triangular shape.

13. 3. The recording medium according to claim 1, wherein the plurality of structures are arranged one-dimensionally.

14. 3. The recording medium according to claim 1, wherein the plurality of structures are arranged two-dimensionally.

15. the recording layer includes first to n-th layers (where n is an integer of 2 or more) each containing a color former having a different color hue; 3. The recording medium according to claim 1, wherein the first to nth layers each have a plurality of the color-forming portions.

16. the recording layer comprises a first layer, a second layer, and a third layer; the first layer, the second layer, and the third layer contain color-forming compounds that develop color hues different from one another; 3. The recording medium according to claim 1, wherein the first layer, the second layer, and the third layer each have a plurality of the color-forming portions.

17. 3. The recording medium according to claim 1, wherein the recording layer contains three types of microcapsules that have different color hues.

18. An exterior member comprising the recording medium according to claim 1 .

Images