Recording media, cards, booklets, electronic devices, passports, and wearable devices

Abstract

Provided is a recording medium capable of suppressing separation between a substrate and a color-producing layer, and between color-producing layers.　The recording medium is equipped with a substrate and a laminate provided on the substrate. The laminate includes a plurality of color-producing layers, and the average peel strength between the substrate and the laminate and between the color-producing layers in the laminate is at least 5N / cm.

Description

[Technical Field]

[0001] This disclosure pertains to a recording medium and a card equipped therewith. 、 booklet Electronic devices, passports and wearable devices Regarding. [Background technology]

[0002] A recording medium has been proposed that features multiple color-developing layers that can be drawn on using laser light. In recent years, the use of such recording media in cards such as financial settlement cards and ID cards, as well as in booklets such as passports, has been considered. In such cards and booklets, it is desirable to prevent the removal of the recording medium from the standpoint of preventing tampering.

[0003] Patent Document 1 proposes a thermal recording medium that has at least an adhesive layer, a support, and a thermal recording layer, and whose surface is made of dimethyl silicone, and which tears when it is tried to peel it off after being adhered to the surface. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-152022 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in conventional recording media, the substrate and the color-developing layer, and the color-developing layers themselves, are bonded together with an adhesive layer. As a result, the strength between the substrate and the color-developing layer, and between the color-developing layers themselves, is insufficient, and there is a risk that the substrate and the color-developing layer, and between the color-developing layers themselves, may be peeled off by cutting tools or the like.

[0006] The purpose of this disclosure is to provide a recording medium capable of suppressing delamination between the substrate and the color-developing layer, and between the color-developing layers themselves, and a card equipped therewith. 、 booklet Electronic devices, passports and wearable devices The objective is to provide. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, Book The recording medium subject to disclosure is, The first substrate and A laminate provided on a first substrate and 、 A laminated layer provided on the laminate, A cover layer provided on the laminated layer and Equipped with, The laminate includes multiple color-developing layers. The average peel strength between the first substrate and the laminate, and the average peel strength between the color-developing layers contained in the laminate, are 5 N / cm or more. the law of nature, The average peel strength between the laminate and the cover layer is 4 N / cm or less. .

[0009] Book Disclosure Card related to teeth, Book Recording media related to disclosure 。

[0010] Book Disclosure Booklet related to teeth, Book Recording media related to disclosure 。 The electronic device relating to this disclosure includes the recording medium relating to this disclosure. The passport relating to this disclosure shall be equipped with the recording medium relating to this disclosure. The wearable device relating to this disclosure is equipped with the recording medium relating to this disclosure.

[0011] In this disclosure, the laminate may further include a plurality of adhesive layers. In this case, the color-developing layer and the adhesive layer may be laminated alternately. The number of adhesive layers of the recording medium is preferably four or less in order to reduce the number of adhesive interfaces that serve as delamination points. However, the number of adhesive layers of the recording medium is not limited to four or less, and may be five or more.

[0012] In this disclosure, when an adhesive layer is provided between two color-developing layers, the average peel strength between color-developing layers contained in the laminate means the average peel strength between color-developing layers bonded together by the adhesive layer.

[0013] In this disclosure, the multiple color-developing layers may exhibit different hues in their color-developed state. In this case, the first color-developing layer may exhibit the first primary color of the three primary colors, the second color-developing layer may exhibit the second primary color of the three primary colors, and the third color-developing layer may exhibit the third primary color of the three primary colors. The three primary colors may be magenta, cyan, and yellow.

[0014] In this disclosure, a card further comprises a card substrate having a first surface and a second surface, and the recording medium of this disclosure may be provided on the first surface and / or the second surface of the card substrate. Here, "and / or" means at least one of the three possibilities, for example, "X and / or Y" means X only, Y only, or X and Y. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a cross-sectional view showing an example of the configuration of a recording medium according to the first embodiment. [Figure 2] Figure 2 shows the test apparatus for the 90-degree peel test. [Figure 3] Figure 3A is a diagram illustrating the preparation steps for the 90-degree peel test. Figure 3B is a diagram of the test apparatus for the 90-degree peel test. [Figure 4] Figure 4 is a cross-sectional view showing an example of the configuration of a recording medium according to the second embodiment. [Figure 5] Figure 5A is a plan view showing an example of the card configuration according to the third embodiment. Figure 5B is a cross-sectional view along the line VB-VB in Figure 5. [Figure 6] Figure 6 is a cross-sectional view showing an example of the configuration of a card according to the fourth embodiment. [Figure 7] Figure 7 is a cross-sectional view showing an example of the configuration of a recording medium according to a modified example. [Figure 8] Figure 8 is a cross-sectional view showing an example of the configuration of a recording medium according to a modified example. [Figure 9]Figure 9 is a cross-sectional view showing an example of the configuration of a recording medium according to a modified example. [Figure 10] Figure 10 is a cross-sectional view showing an example of the configuration of a recording medium according to a modified example. [Figure 11] Figure 11A is a cross-sectional view showing an example of the configuration of a modified card. Figure 11B is a cross-sectional view showing an example of the configuration of a modified card. Figure 11C is a cross-sectional view showing an example of the configuration of a modified card. [Figure 12] Figure 12 is a perspective view showing an example of the structure of a booklet related to a modified example. [Figure 13] Figure 13A is a graph obtained from a 90-degree peel test of the recording medium of Example 1. Figure 13B is a graph obtained from a 90-degree peel test of the recording medium of Example 2. [Figure 14] Figure 14A is a graph obtained from a 90-degree peel test of the recording medium of Example 3. Figure 14B is a graph obtained from a 90-degree peel test of the recording medium of Comparative Example 1. [Modes for carrying out the invention]

[0016] Embodiments of this disclosure will be described in the following order with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts will be denoted by the same reference numerals. 1. First Embodiment (Example of Recording Medium) 1.1 Recording medium configuration 1.2 Method for manufacturing recording media 1.3 Recording method for recording media 1.4 Effects 2. Second Embodiment (Example of Recording Medium) 2.1 Recording medium configuration 2.2 Method for manufacturing recording media 2.3 Effects 3. Third Embodiment (Example of a Card) 3.1 Card Composition 3.2 Card Manufacturing Method 3.3 Effects 4. Fourth Embodiment (Example of a Card) 4.1 Card Composition 4.2 Card Manufacturing Method 4.3 Effects 5 Variations

[0017] <1 First Embodiment> [1.1 Recording medium configuration] Hereinafter, with reference to Figure 1, an example of the configuration of the recording medium 10 according to the first embodiment will be described. The recording medium 10 is configured to change its coloring state by irradiation with laser light (external stimulus). By changing this coloring state, for example, images can be drawn on the recording medium 10. Here, images are not limited to images such as patterns, color patterns, and photographs, but also include text such as characters and symbols.

[0018] The laser light is preferably near-infrared laser light. In this specification, near-infrared laser light refers to laser light having a peak wavelength in the wavelength range of 780 nm and 2.5 μm or less. The change in color state may be reversible or irreversible. That is, the recording medium 10 may be rewritable, allowing images to be rewritten, or it may be write-once, allowing images to be written only once. From the viewpoint of preventing tampering, it is preferable that the change in color state is irreversible.

[0019] The recording medium 10 comprises a base material 11 (first base material), a laminate 20 provided on the base material 11, an adhesive layer (fifth adhesive layer) 12 provided on the laminate 20, and a cover layer 13 provided on the adhesive layer 12. The laminate 20 comprises three adhesive layers (first, second, and third adhesive layers) 21A, 21B, and 21C, and three color-developing layers (first, second, and third color-developing layers) 22A, 22B, and 22C. In this specification, when the adhesive layers 21A, 21B, and 21C are not particularly distinguished and are referred to collectively as adhesive layer 21, they may be referred to collectively as color-developing layer 22. Similarly, when the color-developing layers 22A, 22B, and 22C are not particularly distinguished and are referred to collectively as color-developing layer 22, they may be referred to collectively as color-developing layer 22. Adhesive layers 21A, 21B, 21C, and 12 are examples of the first, second, third, and fifth adhesive layers, respectively. Color-developing layers 22A, 22B, and 22C are examples of the first, second, and third color-developing layers, respectively.

[0020] The color-developing layer 22 and the adhesive layer 21 are alternately laminated on the substrate 11. More specifically, the three adhesive layers 21A, 21B, and 21C and the three color-developing layers 22A, 22B, and 22C are laminated on the substrate 11 in the order of adhesive layer 21A, color-developing layer 22A, adhesive layer 21B, color-developing layer 22B, adhesive layer 21C, and color-developing layer 22C.

[0021] (Base material 11) The base material 11 is a support for supporting the laminate 20. Preferably, the base material 11 is made of a material that has excellent heat resistance and excellent dimensional stability in the planar direction. The base material 11 may have either transmittance or opacity to visible light. In this specification, visible light refers to light in the wavelength range of 360 nm to 780 nm. The base material 11 may have a predetermined color, such as white. The base material 11 has a first surface on which the laminate 20 is provided and a second surface opposite to the first surface. The base material 11 may be, for example, in the form of a plate or a film. In this disclosure, film is defined to include sheets.

[0022] The base material 11 may be rigid or flexible. If a flexible base material 11 is used, a flexible recording medium 10 can be realized. Examples of rigid base materials 11 include wafers or glass substrates. Examples of flexible base materials 11 include flexible glass, film, or paper.

[0023] The substrate 11 includes, for example, at least one selected from the group consisting of inorganic materials, metallic materials, and polymer materials. Examples of inorganic materials include silicon (Si) and silicon dioxide (SiO₂). X ), silicon nitride (SiN X ) and aluminum oxide (AlO X The materials include at least one selected from the group consisting of, for example, glass and spin-on glass (SOG). The silicon dioxide includes at least one selected from the group consisting of, for example, aluminum (Al), nickel (Ni), and stainless steel. The polymer materials include at least one selected from the group consisting of, for example, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethyl ether ketone (PEEK), and polyvinyl chloride (PVC).

[0024] Furthermore, a reflective layer (not shown) may be provided on at least one of the first and second surfaces of the substrate 11, or the substrate 11 itself may also function as a reflective layer. Having such a configuration in the substrate 11 enables clearer color display.

[0025] (Coloring layers 22A, 22B, 22C) In the unrecorded state (initial state), the color-developing layers 22A, 22B, and 22C are in a decolorized state. The color-developing layers 22A, 22B, and 22C can change from a decolorized state to a colored state by irradiation with laser light. The decolorized state may be a state in which the laser light and visible light can pass through.

[0026] Each of the color-developing layers 22A, 22B, and 22C is capable of exhibiting a different hue in its color-developed state. Specifically, color-developing layer 22A is capable of exhibiting magenta in its color-developed state. Color-developing layer 22B is capable of exhibiting cyan in its color-developed state. Color-developing layer 22C is capable of exhibiting yellow in its color-developed state. Magenta, cyan, and yellow are examples of the first, second, and third primary colors, respectively. The first, second, and third primary colors may be colors other than magenta, cyan, and yellow. The laser light capable of changing color-developing layer 22A to a color-developed state, the laser light capable of changing color-developing layer 22B to a color-developed state, and the laser light capable of changing color-developing layer 22C to a color-developed state each have different peak wavelengths.

[0027] The thickness of the color-developing layers 22A, 22B, and 22C is preferably 1 μm to 20 μm, and more preferably 2 μm to 15 μm. If the thickness of the color-developing layers 22A, 22B, and 22C is 1 μm or more, the color density can be improved. On the other hand, if the thickness of the color-developing layers 22A, 22B, and 22C is 20 μm or less, the increase in the amount of heat used by the color-developing layers 22A, 22B, and 22C can be suppressed, and the deterioration of color development can be suppressed.

[0028] The coloring layer 22A comprises a first coloring compound having electron-donating properties, a first color developer having electron-accepting properties, and a first photothermal converter. Preferably, the coloring layer 22A further comprises a first matrix resin.

[0029] The coloring layer 22B comprises a second coloring compound having electron-donating properties, a second color developer having electron-accepting properties, and a second photothermal converter. Preferably, the coloring layer 22B further comprises a second matrix resin.

[0030] The coloring layer 22C comprises a third coloring compound having electron-donating properties, a third color developer having electron-accepting properties, and a third photothermal converter. Preferably, the coloring layer 22C further comprises a third matrix resin.

[0031] (The first, second, and third color-producing compounds) The first, second, and third color-developing compounds may be one or multiple types, and each can develop color by reacting with the first, second, and third color developers. The first, second, and third color-developing compounds can exhibit different hues in their developed state. Specifically, the first color-developing compound can exhibit magenta in its developed state. The second color-developing compound can exhibit cyan in its developed state. The third color-developing compound can exhibit yellow in its developed state.

[0032] The first, second, and third color-developing compounds are, for example, leuco dyes. When the lactone ring in a leuco dye reacts with an acid, the lactone ring opens and develops color. When the open lactone ring in a leuco dye reacts with a base, it closes and becomes colorless. The leuco dye may be, for example, an existing dye for thermal paper.

[0033] The first, second, and third color-developing compounds are not particularly limited and can be appropriately selected depending on the purpose. The first, second, and third color-developing compounds include, for example, at least one selected from the group consisting of fluorane compounds, triphenylmethanephthalide compounds, azaphthalide compounds, phenothiazine compounds, leucoauramine compounds, and indolinophthalide compounds. In addition, the first, second, and third chromogenic compounds include, for example, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-di(n-butylamino)fluorane, 2-anilino-3-methyl-6-(Nn-propyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-isopropyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-isobutyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(Nn-amyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-sec-butyl-N-methylamino)fluorane, 2-anilino- 3-methyl-6-(N-iso-amyl-N-ethylamino)fluorane, 2-anilino-3-methyl-6-(Nn-propyl-N-isopropylamino)fluorane, 2-anilino-3-methyl-6-(N-cyclohexyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-ethyl-p-toluidino)fluorane, 2-anilino-3-methyl-6-(N-methyl-p-toluidino)fluorane, 2-(m-trichloromethylanilino)-3-methyl-6-diethylaminofluorane, 2-(m-trifluoromethylanilino)-3-methyl-6-diethylaminofluorane, 2-(m-trichloromethylanilino)-3-methyl-6-(N-cyclohexyl-N-methylamino)fluorane, 2-(2,4-dimethylanilino)-3-methyl-6-diethylaminofluorane, 2-(N-ethyl-p-toluidino)-3-methyl-6-(N-ethylanilino)fluorane, 2-(N-ethyl-p-toluidino)-3-methyl-6-(N-propyl-p-toluidino)fluorane, 2-anilino-6-(Nn-hexyl-N-ethylamino)fluorane, 2-(o-chloroanilino)-6-diethylaminofluorane, 2-(o-chloroanilino)-6-dibutylaminofluorane, 2-(m-trifluoromethylanilino)-6-diethylaminofluorane, 2,3-dimethyl-6-dimethylaminofluorane, 3-methyl-6-(N-ethyl-p-toluidino)fluorane, 2-chloro-6 -Diethylaminofluorane, 2-bromo-6-diethylaminofluorane, 2-chloro-6-dipropylaminofluorane, 3-chloro-6-cyclohexylaminofluorane, 3-bromo-6-cyclohexylaminofluorane, 2-chloro-6-(N-ethyl-N-isoamylamino)fluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-(o-chloroanilino)-3-chloro-6-cyclohexylaminofluorane, 2-(m-trifluoromethylanilino)-3-chloro-6-diethylaminofluorane, 2-(2,3-dichloroanilino)-3-chloro-6-diethylaminofluorane, 1,2-Benzo-6-diethylaminofluorane, 3-diethylamino-6-(m-trifluoromethylanilino)fluorane, 3-(1-ethyl-2-methylindole-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindole-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-7-azaphthalide, 3-(1-octyl- 2-methylindole-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindole-3-yl)-3-(2-methyl-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindole-3-yl)-3-(2-methyl-4-diethylaminophenyl)-7-azaphthalide, 3-(1-ethyl-2-methylin Dol-3-yl)-3-(4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindole-3-yl)-3-(4-Nn-amyl-N-methylaminophenyl)-4-azaphthalide, 3-(1-methyl-2-methylindole-3-yl)-3-(2-hexyloxy-4-diethylaminophenyl)-4-azaphthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl) Phenyl)-4-azaphthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-7-azaphthalide, 2-(p-acetylanilino)-6-(Nn-amyl-Nn-butylamino)fluorane, 2-benzylamino-6-(N-ethyl-p-toluidino)fluorane, 2-benzylamino-6-(N-methyl-2,4-dimethylanilino)fluorane, 2-benzylamino-6-(N-ethyl-2,4-dimethylanilino)fluorane, 2-benzylamino-6-(N-methyl-p-toluidino)fluorane, 2-benzylamino-6-(N-ethyl-p-toluidino)fluorane, 2-(di-p-methylbenzylamino)-6-(N-ethyl-p-toluidino)fluorane, 2-(α-phenylethylamino)-6-(N-ethyl-p-toluidino)fluorane, 2-methylamino-6-(N-methylanilino)fluorane, 2-methylamino-6-(N-ethylanilino)fluorane, 2-methylamino-6-(N-propylanilino)fluorane , 2-ethylamino-6-(N-methyl-p-toluidino)fluorane, 2-methylamino-6-(N-methyl-2,4-dimethylanilino)fluorane, 2-ethylamino-6-(N-ethyl-2,4-dimethylanilino)fluorane, 2-dimethylamino-6-(N-methylanilino)fluorane, 2-dimethylamino-6-(N-ethylanilino)fluorane, 2-diethylamino-6-(N-methyl-p-toluidino)fluorane, 2-diethylamino-6-(N-ethyl-p-toluidino)fluorane, 2-dipropylamino-6-(N-methyl Fluoranilino)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 (Tyl-p-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,It may contain at least one selected from the group consisting of 2 - benzo - 6 - (N - ethyl - N - isoamylamino) fluoran, 1,2 - benzo - 6 - dibutylamino fluoran, 1,2 - benzo - 6 - (N - methyl - N - cyclohexylamino) fluoran, 1,2 - benzo - 6 - (N - ethyl - N - toluidino) fluoran, and the like.,

[0034] (First, second, and third developers) The first, second, and third developers can each cause the first, second, and third color - forming compounds in the decolorized state to develop color. The types of the first, second, and third developers may be the same, or the types of the first, second, and third developers may be different from each other. The first, second, and third developers are compounds containing a group having an electron - accepting property in the molecule. The electron - accepting parts of the first, second, and third developers react with the lactone rings of the first, second, and third color - forming compounds respectively, and the lactone rings open, causing the first, second, and third color - forming compounds to develop color. The first, second, and third developers include, for example, at least one selected from the group consisting of phenol derivatives, salicylic acid derivatives, and urea derivatives.,

[0035] Specifically, for example, the developer contains a compound represented by the following formula (1). [Chemical formula] (However, in formula (1), X 0 is a divalent group containing at least one benzene ring. Y 01 , Y 02 are each independently a monovalent group. n01 and n02 are each independently an integer from 0 to 5. When n01 is an integer from 2 to 5, Y 01 may be the same as or different from each other. When n02 is an integer from 2 to 5, Y 02 may be the same as or different from each other. Z 01 , Z<00​​​​​0 X contains at least one benzene ring. 0 Since the melting point can be made higher compared to when it is an aliphatic hydrocarbon group (e.g., a normal alkyl chain), the color retention characteristics during high-temperature, high-humidity storage (hereinafter referred to as "high-temperature, high-humidity storage characteristics") can be improved. From the viewpoint of improving high-temperature, high-humidity storage characteristics and heat resistance, X 0 However, it is preferable that it contains at least two benzene rings. High-temperature, high-humidity storage characteristics refer to, for example, storage characteristics under conditions of 80°C and 60%RH. Improved heat resistance enhances the resistance of the recording medium 10 to harsh processes (e.g., heated pressing or integral molding using molten resin, etc.). 0 If it contains at least two benzene rings, at least two benzene rings may be fused together. For example, it may be naphthalene or anthracene, etc.

[0037] Z 01 , Z 02 Because each of these groups is independently a hydrogen bonding group, the color developers tend to remain somewhat cohesive through hydrogen bonding, thereby improving the stability of the color developers within the color development layers 22A, 22B, and 22C. In this specification, a hydrogen bonding group means a functional group that contains an atom capable of forming hydrogen bonds with other functional groups or atoms present in other compounds.

[0038] The color developer preferably contains a compound represented by the following formula (2). [ka] (However, in equation (2), X 1 Y is a divalent group containing at least one benzene ring. 11 , Y 12 , Y 13 , Y 14 Each of them is an independent, undivided base. Z 11 , Z 12 Each of these is an independent hydrogen bonding group.

[0039] X 1 X contains at least one benzene ring.1 Since the melting point can be increased compared to when it is an aliphatic hydrocarbon group (e.g., a normal alkyl chain), the high-temperature, high-humidity storage characteristics can be improved. From the viewpoint of improving high-temperature, high-humidity storage characteristics and heat resistance, X 1 However, it is preferable that it contains at least two benzene rings. 1 If it contains at least two benzene rings, at least two benzene rings may be fused together. For example, it may be naphthalene or anthracene, etc.

[0040] Z 11 , Z 12 Because each of these groups is independently a hydrogen bonding group, the color developers tend to remain somewhat cohesive through hydrogen bonding, thereby improving the stability of the color developers within the color development layers 22A, 22B, and 22C.

[0041] When formulas (1) and (2) contain hydrocarbon groups, these hydrocarbon groups are a general term for groups composed of carbon (C) and hydrogen (H), and may be saturated hydrocarbon groups or unsaturated hydrocarbon groups. Saturated hydrocarbon groups are aliphatic hydrocarbon groups that do not have multiple carbon-carbon bonds, and unsaturated hydrocarbon groups are aliphatic hydrocarbon groups that have multiple carbon-carbon bonds (carbon-carbon double bonds or carbon-carbon triple bonds).

[0042] If formulas (1) and (2) contain a hydrocarbon group, the hydrocarbon group may be in the form of a chain or may contain one or more rings. The chain may be a straight chain or a branched chain having one or more side chains, etc.

[0043] (X containing one benzene ring) 0 , X 1 ) X in equation (1) 0 and X in equation (2) 1 This is, for example, a divalent group containing one benzene ring. This divalent group can be represented, for example, by the following formula (3). [ka] (However, in equation (3), X 21 It can be there or not, X 21 If X 21 X is a divalent group. 22 It can be there or not, X 22 If X 22 R is a divalent group. 21 is a single-valued base. n21 is an integer from 0 to 4. If n21 is an integer from 2 to 4, then R 21 These elements may be identical or different. (* indicates a connection point.)

[0044] In equation (3), X relative to the benzene ring 21 and X 22 The bonding position of X is not limited. That is, X relative to the benzene ring. 21 and X 22 The bond position may be the ortho, meta, or para position.

[0045] The above divalent group containing one benzene ring is preferably represented by the following formula (4) from the viewpoint of improving high-temperature and high-humidity storage characteristics. [ka] (However, in equation (4), R 22 is a single-valued base. n²² is an integer from 0 to 4. If n²² is an integer from 2 to 4, then R 22 These elements may be identical or different. (* indicates a connection point.)

[0046] X in equation (1) 0 If is a divalent group containing one benzene ring, then in formula (4), Z relative to the benzene ring 01 and Z 02 The bonding position is not limited. That is, Z relative to the benzene ring. 01 and Z 02 The bond position may be the ortho, meta, or para position.

[0047] X in equation (2)1 If is a divalent group containing one benzene ring, then in formula (4), Z relative to the benzene ring 11 and Z 12 The bonding position is not limited. That is, Z relative to the benzene ring. 11 and Z 12 The bond position may be the ortho, meta, or para position.

[0048] (X 21 , X 22 ) X in equation (3) 21 , X 22 Each of these groups can be independently a divalent group and is not particularly limited, but examples include hydrocarbon groups which may have substituents. The hydrocarbon groups are preferably in a chain form. When the hydrocarbon groups are in a chain form, the melting point of the color developer can be reduced, so that the color developer dissolves upon irradiation with laser light and the color-developing compound becomes easier to color. From the viewpoint of reducing the melting point of the color developer, among the chain-like hydrocarbon groups, a n-alkyl chain is particularly preferred.

[0049] The number of carbon atoms in the hydrocarbon group, which may have substituents, is, for example, 1 to 15, 1 to 13, 1 to 12, 1 to 10, 1 to 6, or 1 to 3.

[0050] X in equation (3) 21 , X 22 When the normal alkyl group is a normal alkyl group, the number of carbon atoms in the normal alkyl group is preferably 8 or less, more preferably 6 or less, even more preferably 5 or less, and particularly preferably 3 or less, from the viewpoint of high-temperature storage stability. When the number of carbon atoms in the normal alkyl group is 8 or less, the length of the normal alkyl group is short, so thermal disturbance is less likely to occur in the color developer during high-temperature storage, and the site that interacted with the color-developing compound such as leuco dye during color development is less likely to detach. Therefore, the color-developing compound such as leuco dye is less likely to lose its color during high-temperature storage, thus improving high-temperature storage stability.

[0051] Examples of substituents that a hydrocarbon group may have include halogen groups (e.g., fluorine groups) or alkyl groups having halogen groups (e.g., fluorine groups). A hydrocarbon group that may have substituents may be one in which some of the carbon atoms of the hydrocarbon group (e.g., some of the carbon atoms in the main chain of the hydrocarbon group) are substituted with an element such as oxygen.

[0052] (R 21 ) R in equation (3) 21 This can be any monovalent group and is not particularly limited, but examples include a halogen group or a hydrocarbon group which may have substituents.

[0053] Halogen groups include, for example, fluorine (-F), chlorine (-Cl), bromine (-Br), or iodine (-I).

[0054] The number of carbon atoms in the hydrocarbon group, which may have substituents, is, for example, 1 to 15, 1 to 13, 1 to 12, 1 to 10, 1 to 6, or 1 to 3.

[0055] Examples of substituents that a hydrocarbon group may have include halogen groups (e.g., fluorine groups) or alkyl groups having halogen groups (e.g., fluorine groups). A hydrocarbon group that may have substituents may be one in which some of the carbon atoms of the hydrocarbon group (e.g., some of the carbon atoms in the main chain of the hydrocarbon group) are substituted with an element such as oxygen.

[0056] (R 22 ) R in equation (4) 22 R can be any monovalent group and is not particularly limited, but examples include a halogen group or a hydrocarbon group which may have a substituent. The halogen group and the hydrocarbon group which may have a substituent are R in formula (3) above, respectively. 21 It is similar to that.

[0057] (X containing two benzene rings) 0 , X 1 ) X in formula (1) 0 and X in formula (2) 1 is a divalent group containing, for example, two benzene rings. The divalent group is represented by, for example, the following formula (5). [Chemical formula] (However, in formula (5), X 31 may or may not be present. When X 31 is present, X 31 is a divalent group. X 32 may or may not be present. When X 32 is present, X 32 is a divalent group. X 33 may or may not be present. When X 33 is present, X 33 is a divalent group. R 31 , R 32 are each independently a monovalent group. n31 and n32 are each independently an integer from 0 to 4. When n31 is an integer from 2 to 4, R 31 may be the same as or different from each other. When n32 is an integer from 2 to 4, R 32 may be the same as or different from each other. The * mark represents a bonding site.)

[0058] In formula (5), the bonding positions of X 31 and X 32 to the benzene ring are not limited. That is, the bonding positions of X 31 and X 32 to the benzene ring may be any of the ortho, meta, and para positions. Similarly, in formula (5), the bonding positions of X 32 and X 33 to the benzene ring are not limited. That is, the bonding positions of X 32 and X 33 to the benzene ring may be any of the ortho, meta, and para positions.<000050​​The divalent group containing two benzene rings is preferably represented by the following formula (6) from the viewpoint of improving the high-temperature and high-humidity storage characteristics. [Chemical Formula] (However, in formula (6), X 34 is a divalent group. R 33 , R 34 are each independently a monovalent group. n33 and n34 are each independently an integer from 0 to 4. When n33 is an integer from 2 to 4, R 33 may be the same as or different from each other. When n34 is an integer from 2 to 4, R 34 may be the same as or different from each other. The * mark represents the bonding site.)

[0060] When X 0 in formula (1) is a divalent group containing two benzene rings, in formula (6), the bonding positions of Z 01 and X 34 to the benzene ring are not limited. That is, the bonding positions of Z 01 and X 34 to the benzene ring may be any of the ortho position, meta position, and para position. Similarly, in formula (6), the bonding positions of Z 02 and X 34 to the benzene ring are not limited. That is, the bonding positions of Z 02 and X 34 to the benzene ring may be any of the ortho position, meta position, and para position.

[0061] When X 1 in formula (2) is a divalent group containing two benzene rings, in formula (6), the bonding positions of Z 11 and X 34 to the benzene ring are not limited. That is, the bonding positions of Z <000011E>and X 34 to the benzene ring may be any of the ortho position, meta position, and para position. Similarly, in formula (6), the bonding positions of Z 12 and X34 The bonding position is not limited. That is, Z relative to the benzene ring. 12 and X 34 The bond position may be the ortho, meta, or para position.

[0062] (X 31 , X 32 , X 33 ) X in equation (5) 31 , X 32 , X 33 Each of these can be a divalent group, and is not particularly limited, but an example would be a hydrocarbon group which may have substituents. The hydrocarbon group is X in formula (3) above. 21 , X 22 It is similar to that.

[0063] (X 34 ) X in equation (6) 34 X can be any divalent group and is not particularly limited, but an example is a hydrocarbon group which may have substituents. The hydrocarbon group is X in formula (3) above. 21 , X 22 It is similar to that.

[0064] (R 31 , R 32 ) R in equation (5) 31 , R 32 R can be any monovalent group and is not particularly limited, but examples include a halogen group or a hydrocarbon group which may have substituents. The halogen group and the hydrocarbon group which may have substituents are R in formula (3) above, respectively. 21 It is similar to that.

[0065] (R 33 , R 34 ) R in equation (6) 33 , R 34R can be any monovalent group and is not particularly limited, but examples include a halogen group or a hydrocarbon group which may have substituents. The halogen group and the hydrocarbon group which may have substituents are R in formula (3) above, respectively. 21 It is similar to that.

[0066] (Y 01 , Y 02 ) Y in equation (1) 01 , Y 02 Each of these is independently, for example, a hydrogen group (-H), a hydroxyl group (-OH), a halogen group (-X), a carboxyl group (-COOH), an ester group (-COOR), or a hydrocarbon group which may have a substituent.

[0067] Halogen groups include, for example, fluorine (-F), chlorine (-Cl), bromine (-Br), or iodine (-I).

[0068] The number of carbon atoms in the hydrocarbon group, which may have substituents, is, for example, 1 to 15, 1 to 13, 1 to 12, 1 to 10, 1 to 6, or 1 to 3.

[0069] Examples of substituents that a hydrocarbon group may have include halogen groups (e.g., fluorine groups) or alkyl groups having halogen groups (e.g., fluorine groups). A hydrocarbon group that may have substituents may be one in which some of the carbon atoms of the hydrocarbon group (e.g., some of the carbon atoms in the main chain of the hydrocarbon group) are substituted with an element such as oxygen.

[0070] In equation (1), (Y 01 ) n01 one of the following, and / or (Y 02 ) n02 It is preferable that one of them is a hydroxyl group (-OH). (Y 01 ) n01 one of the following, and / or (Y 02 ) n02 One of these groups is a hydroxyl group (-OH), which improves label quality and lightfastness.

[0071] (Y 11 , Y 12 , Y 13 , Y 14 ) In equation (2), Y relative to the benzene ring 11 and Y 12 The bonding position is not limited. That is, Y relative to the benzene ring. 11 and Y 12 The bond position of can be any of the ortho, meta, or para positions. Similarly, in formula (2), Y relative to the benzene ring 13 and Y 14 The bonding position is not limited. That is, Y relative to the benzene ring. 13 and Y 14 The bond position may be any of the ortho, meta, or para positions. In formula (2), Y for one of the benzenes 11 and Y 12 The bond position of and Y relative to the other benzene 13 and Y 14 The bonding position may be the same as or different from that position.

[0072] Y in equation (2) 11 , Y 12 , Y 13 , Y 14 Each of these is independently, for example, a hydrogen group (-H), a hydroxyl group (-OH), a halogen group, a carboxyl group (-COOH), an ester group (-COOR), or a hydrocarbon group which may have a substituent. The halogen group and the hydrocarbon group which may have a substituent are, respectively, Y in formula (1) above. 01 , Y 02 It is similar to that.

[0073] In equation (2), Y 11 and / or Y 13 It is preferable that it is a hydroxyl group (-OH). 11 and / or Y 13 The presence of a hydroxyl group (-OH) improves both label quality and lightfastness.

[0074] (Z 01 , Z 02 ) Z in equation (1) 01 , Z 02 These are, independently of each other, for example, urea bonds (-NHCONH-), amide bonds (-NHCO-, -OCHN-), or hydrazide bonds (-NHCOCONH-). From the viewpoint of improving high temperature and high humidity storage characteristics, Z 01 , Z 02 It is preferable that it is a urea bond. 01 If it is an amide bond, the nitrogen contained in the amide bond may be bonded to benzene, or the carbon contained in the amide bond may be bonded to benzene. 02 If the bond is an amide bond, the nitrogen contained in the amide bond may be bonded to benzene, or the carbon contained in the amide bond may be bonded to benzene.

[0075] (Z 11 , Z 12 ) Z in equation (2) 11 , Z 12 These are, independently of each other, for example, urea bonds (-NHCONH-), amide bonds (-NHCO-, -OCHN-), or hydrazide bonds (-NHCOCONH-). From the viewpoint of improving high temperature and high humidity storage characteristics, Z 11 , Z 12 It is preferable that it is a urea bond. 11 If it is an amide bond, the nitrogen contained in the amide bond may be bonded to benzene, or the carbon contained in the amide bond may be bonded to benzene. 12 If the bond is an amide bond, the nitrogen contained in the amide bond may be bonded to benzene, or the carbon contained in the amide bond may be bonded to benzene.

[0076] (Specific examples of color developers) X in equation (1) 0 and X in equation (2) 1A color developer containing one benzene ring specifically includes, for example, at least one selected from the group consisting of compounds represented by the following formulas (7-1) to (7-6). [ka]

[0077] X in equation (1) 0 and X in equation (2) 1 A color developer containing two benzene rings specifically includes, for example, at least one selected from the group consisting of compounds represented by the following formulas (8-1) to (8-8). [ka]

[0078] (First, second, and third photothermal converters) The first, second, and third photothermal converters are capable of absorbing light in a predetermined wavelength range, such as the near-infrared region, and generating heat. The first, second, and third photothermal converters have different absorption wavelength peaks. Specifically, the first photothermal converter has an absorption wavelength peak at wavelength λ1. The second photothermal converter has an absorption wavelength peak at wavelength λ2. The third photothermal converter has an absorption wavelength peak at wavelength λ3. Wavelengths λ1, λ2, and λ3 are different. It is preferable that the absorption wavelength peaks are in the near-infrared region. The near-infrared region is, for example, the range of wavelengths from 700 nm to 2000 nm. As described above, because the first, second, and third photothermal converters have different absorption wavelength peaks, it is possible to selectively color one of the color-developing layers 22A, 22B, and 22C by irradiation with laser light. It is preferable to use near-infrared absorbing dyes that have almost no absorption in the visible region as the first, second, and third photothermal converters.

[0079] The first, second, and third photothermal converters each include, for example, at least one selected from the group consisting of compounds having a phthalocyanine skeleton (phthalocyanine dyes), compounds having a squarylium skeleton (squirlium dyes), and inorganic compounds.

[0080] The inorganic compound includes, for example, at least one selected from the group consisting of metal complexes such as dithio complexes, diimonium salts, aminium salts, graphite, carbon black, metal powder particles, cobalt tetroxide, iron oxide, chromium oxide, copper oxide, titanium black, metal oxides such as ITO (Indium Tin Oxide), metal nitrides such as niobium nitride, metal carbides such as tantalum carbide, metal sulfides, and various magnetic powders. In addition, the inorganic compound may include compounds having a cyanine skeleton (cyanine dyes) that have excellent lightfastness and heat resistance. Here, excellent lightfastness means that it does not decompose under the usage environment, for example, when exposed to light from a fluorescent lamp. Excellent heat resistance means that, for example, when formed into a film with a polymer material and stored at, for example, 150°C for 30 minutes, there is no change of more than 20% in the maximum absorption peak value of the absorption spectrum. Examples of compounds having such a cyanine skeleton include those having at least one of the following counterions in the molecule: SbF6, PF6, BF4, ClO4, CF3SO3, and (CF3SO3)2N, and a methine chain containing a five-membered ring or a six-membered ring. In the first embodiment, it is preferable that the cyanine skeleton compound used in the recording medium 10 has both one of the above counterions 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 can be ensured if at least one of them is present.

[0081] (First, second, and third matrix resins) The first, second, and third matrix resins preferably function as binders. The first matrix resin is preferably one in which the first color-developing compound, the first color developer, and the first photothermal converter can be homogeneously dispersed. The second matrix resin is preferably one in which the second color-developing compound, the second color developer, and the second photothermal converter can be homogeneously dispersed. The third matrix resin is preferably one in which the third color-developing compound, the third color developer, and the third photothermal converter can be homogeneously dispersed. The first, second, and third matrix resins may be the same type, or they may be different types.

[0082] The first, second, and third matrix resins each include at least one selected from the group consisting of, for example, thermosetting resins and thermoplastic resins. Preferably, the first, second, and third matrix resins include polycarbonate resins. By including polycarbonate resins in the first, second, and third matrix resins, the light resistance of the surface of the recording medium 10 can be improved. Here, a polycarbonate resin is a resin having at least a carbonate group (-O-(C=O)-O-) as a structural unit in its main chain. Therefore, it may have other structural units in addition to carbonate groups in its main chain.

[0083] The first, second, and third matrix resins may, in place of or in combination with polycarbonate resins, contain at least one selected from the group consisting of polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethylcellulose, polystyrene, styrene copolymer, phenoxy resin, polyester, aromatic polyester, polyurethane, polyacrylic acid ester, polymethacrylic acid ester, acrylic acid copolymer, maleic acid polymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethylcellulose, carboxymethylcellulose, and starch.

[0084] (Additives) The color-developing layers 22A, 22B, and 22C may further contain at least one additive selected from the group consisting of sensitizers and ultraviolet absorbers, etc., as needed. From the viewpoint of suppressing scalp discoloration, it is preferable that the color-developing layers 22A, 22B, and 22C contain amine compounds.

[0085] When the color-developing layers 22A, 22B, and 22C contain an amine-based compound, it is preferable that the color-developing layers 22A, 22B, and 22C also contain at least one compound selected from the group consisting of epoxy-based compounds and carbodiimide-based compounds, along with the amine-based compound. If the color-developing layers 22A, 22B, and 22C contain an amine-based compound, the reliability of the color-developing portion may decrease during high-temperature, high-humidity storage. However, if the color-developing layers 22A, 22B, and 22C also contain at least one compound selected from the group consisting of epoxy-based compounds and carbodiimide-based compounds, along with the amine-based compound, the decrease in the reliability of the color-developing portion during high-temperature, high-humidity storage due to the amine-based compound can be suppressed.

[0086] (Adhesive layer 21A, 21B, 21C, 12) Adhesive layer 21A is provided between the substrate 11 and the color-developing layer 22A, and adheres the substrate 11 and the color-developing layer 22A. Adhesive layer 21B is provided between the color-developing layers 22A and 22B, and adheres the color-developing layers 22A and 22B. Adhesive layer 21B may also serve as an insulating layer capable of insulating the space between the color-developing layers 22A and 22B. Adhesive layer 21C is provided between the color-developing layers 22B and 22C, and adheres the color-developing layers 22B and 22C. Adhesive layer 21C may also serve as an insulating layer capable of insulating the space between the color-developing layers 22B and 22C. Adhesive layer 12 is provided between the laminate 20 and the cover layer 13, and adheres the laminate 20 and the cover layer 13.

[0087] The adhesive layers 21B, 21C, and 12 are transparent to the laser light and visible light used for writing on the recording medium 10. The adhesive layer 21A may be transparent to or opaque to the laser light and visible light used for writing on the recording medium 10.

[0088] Adhesive layers 21A, 21B, 21C, and 12 preferably contain a thermosetting resin as a thermosetting adhesive. By including a thermosetting resin in adhesive layers 21A, 21B, 21C, and 12, a higher average peel strength (i.e., an average peel strength of 5 N / cm or more) can be obtained compared to when each layer is bonded together with an adhesive layer. The thermosetting resin includes, for example, at least one selected from the group consisting of silicone resins, epoxy resins, urea resins, resorcinol resins, melamine resins, phenolic resins, polyurethane resins, polyester resins, polyimide resins, acrylic resins, and polyaromatic resins. Adhesive layers 21A, 21B, 21C, and 12 may also contain various additives, such as ultraviolet absorbers. The adhesive layers 21A, 21B, 21C, and 12 may be formed by coating or by using a sheet. Using a sheet can suppress process damage to other layers.

[0089] The adhesive layers 21A, 21B, 21C, and 12 may contain a UV-curable resin as an UV-curable adhesive along with the thermosetting resin, or they may contain a UV-curable resin as an UV-curable adhesive instead of the thermosetting resin. The UV-curable resin includes, for example, at least one selected from the group consisting of acrylic resins and epoxy resins.

[0090] The thickness of the adhesive layer 21A is preferably 3 μm to 100 μm, more preferably 5 μm to 50 μm, and even more preferably 10 μm to 50 μm or 15 μm to 50 μm. If the thickness of the adhesive layer 21A is less than 3 μm, there is a risk that the desired adhesive strength cannot be maintained due to insufficient thickness. On the other hand, if the thickness of the adhesive layer 21A exceeds 100 μm, there is a risk that the bending resistance of the recording medium 10 will decrease, making it more susceptible to defects such as cracking.

[0091] The thickness of the adhesive layers 21B and 21C is preferably 3 μm to 100 μm, more preferably 5 μm to 50 μm, and even more preferably 10 μm to 50 μm or 15 μm to 50 μm. If the thickness of the adhesive layers 21B and 21C is less than 3 μm, there is a risk that the desired adhesive strength will not be maintained due to insufficient thickness. Also, sufficient heat insulation effect as a heat insulating layer will not be obtained, so when a specific color-developing layer 22 is heated and colored by laser light irradiation, heat may be transmitted to adjacent color-developing layers 22, causing adjacent color-developing layers 22 to color unintentionally. In other words, there is a risk that the desired color expression will not be obtained through color mixing. On the other hand, if the thickness of the adhesive layers 21B and 21C exceeds 100 μm, there is a risk that the transmittance to laser light and visible light used for drawing on the recording medium 10 will decrease. Also, there is a risk that the bending resistance of the recording medium 10 will decrease, making it more susceptible to defects such as cracks.

[0092] The thickness of the adhesive layer 12 is preferably 3 μm to 100 μm, more preferably 5 μm to 50 μm, and even more preferably 10 μm to 50 μm or 15 μm to 50 μm. If the thickness of the adhesive layer 12 is less than 3 μm, there is a risk that the desired adhesive strength cannot be maintained due to insufficient thickness. On the other hand, if the thickness of the adhesive layer 12 exceeds 100 μm, there is a risk that the transmittance to the laser light and visible light used for writing on the recording medium 10 will decrease. In addition, there is a risk that the bending resistance of the recording medium 10 will decrease, making it more susceptible to defects such as cracking.

[0093] (Average peel strength) The average peel strength between the substrate 11 and the laminate 20, the average peel strength between the color-developing layers 22 contained in the laminate 20, and the average peel strength between the laminate 20 and the cover layer 13 are 5 N / cm or more, preferably 8 N / cm or more, more preferably 10 N / cm or more, and even more preferably 15 N / cm or more. As described above, when the average peel strength between each layer is 5 N / cm or more, peeling between the substrate 11 and the laminate 20, peeling between the color-developing layers 22 contained in the laminate 20, and peeling between the laminate 20 and the cover layer 13 can be suppressed. Therefore, tampering with the recording medium 10 can be prevented. Specifically, the average peel strength between the color-developing layers 22 contained in the laminate 20 refers to the average peel strength between color-developing layer 22A and color-developing layer 22B, and the average peel strength between color-developing layer 22B and color-developing layer 22C. The upper limits for the average peel strength between the base material 11 and the laminate 20, the average peel strength between the color-developing layers 22 contained in the laminate 20, and the average peel strength between the laminate 20 and the cover layer 13 are not particularly limited, but for example, they are 20 N / cm or less. If the upper limit of the average peel strength exceeds 20 N / cm, it is expected that the measurement gauge will reach its limit and measurement will become impossible, or the test piece 60 will break below the gripping allowance of the adherend 61 or tensile member 62, making measurement impossible (see Figure 2).

[0094] The average peel strength between the substrate 11 and the laminate 20 is determined by performing a 90-degree peel test. The 90-degree peel test will be described below with reference to Figure 2.

[0095] First, the recording medium 10 is cut into a strip 10 mm wide and 100 mm long to prepare a test piece 60, which is left in a standard atmosphere of 23 ± 1 °C and 50 ± 5% relative humidity for 24 hours or more. Hereinafter, the laminated portion of the test piece 60 above the interface between the base material 11 and the laminate 20 will be referred to as the adherend 61. Next, at one end of the test piece 60 in the longitudinal direction, a notch is made between the base material 11 and the adherend 61 of the test piece 60 using a sharp blade such as a cutter, and the adherend 61 is peeled off in the longitudinal direction for a length of 20 mm to create a gripping area. Then, the side of the test piece 60 facing the base material 11 is fixed to the test stand 71 with a strong adhesive. As for the adhesive, one with sufficiently high adhesive strength is selected so that the base material 11 does not peel off from the test stand 71 when measuring the peel strength between the base material 11 and the adherend 61, such as 3M's Scotch® strong adhesive tape. Figure 2 shows an example where the tension member 62 is used as a gripping space. However, if there is sufficient stroke before the adherend 61 is clamped by the clamping device (metal plate) 63, the adherend 61 may be clamped directly without using the tension member 62. The tension member 62 is a strip of film with sufficient strength so as not to elongate or break during the measurement of peel strength. In addition, one end of the tension member 62 is attached to the adherend 61 with sufficiently high adhesive force so as not to peel off from the adherend 61 during the measurement of peel strength.

[0096] Next, the gripping portion of the tensile member 62 is passed between a pair of movable rolls 73A and 73B of the jig 72, and then the gripping portion is clamped and fixed by 10 mm or more using the clamping device (metal plate) 63 of the SV-55C 2H tensile and compression testing machine manufactured by Imada Seisakusho Co., Ltd. The movable rolls 73A and 73B serve as the fulcrum for peeling during the 90-degree peel test. Next, the 90-degree peel test is performed using the tensile and compression testing machine, and the test force [N / cm] and stroke [mm] are monitored as voltage values, for example, using a data logger manufactured by Keyence Corporation, converted to force, and stored in memory as CSV output data. The above 90-degree peel test is performed at a tensile speed of 5 mm / sec. under standard conditions of a temperature of 23 ± 1°C and a relative humidity of 50 ± 5%. The stroke is set to 50 mm or more.

[0097] The above 90-degree peel test is performed a total of three times. The point where the peel strength is stable (the position where the force rises gradually, for example, from a distance of 32 mm onwards in Figure 13A) is used as the starting point (0 mm), and the CSV output data from that point to a relative distance of 50 mm is arithmetic mean to calculate the average value. This allows the average peel strength between the substrate 11 and the laminate 20 (adhered body 61) to be determined. However, points where the peel force suddenly drops (spikes) are excluded from the CSV output data. Figure 13A shows an example of data obtained from the 90-degree peel test.

[0098] The average peel strength between the color-developing layers 22 contained in the laminate 20, and the average peel strength between the laminate 20 and the cover layer 13, are determined by the same procedure as the average peel strength between the substrate 11 and the laminate 20 described above.

[0099] The average of the minimum peel strengths between each layer constituting the recording medium 10 is 5 N / cm or more, preferably 8 N / cm or more, more preferably 10 N / cm or more, and even more preferably 15 N / cm or more. As described above, when the average of the minimum peel strengths is 5 N / cm or more, peeling between each layer constituting the recording medium 10 can be suppressed. Therefore, tampering with the recording medium 10 can be prevented.

[0100] The average of the minimum peel strengths between each layer constituting the recording medium 10 is determined by performing a 90-degree peel test. The 90-degree peel test will be described below with reference to Figures 3A and 3B.

[0101] First, the recording medium 10 is cut into a strip 10 mm wide and 100 mm long to prepare a test piece 60, which is left in a standard atmosphere of 23 ± 1 °C and 50 ± 5% relative humidity for 24 hours or more. Next, as shown in Figure 3A, the surface of the test piece 60 facing the substrate 11 is fixed to the test stand 71 with a strong adhesive, and the tensile member 62 is attached to the surface of the test piece 60 facing the cover layer 13. As the tensile member 62, a strip of film with sufficient strength is used so as not to elongate or break when measuring the average peel strength. In addition, one end of the tensile member 62 is attached to the adherend 61 with sufficiently high adhesive strength so as not to peel off from the adherend 61 when measuring the average peel strength.

[0102] Next, as shown in Figure 3B, the gripping portion of the tensile member 62 is passed between a pair of movable rolls 73A and 73B of the jig 72, and then the gripping portion is clamped and fixed by 10 mm or more using the clamping device (metal plate) 63 of the tensile and compression testing machine SV-55C 2H manufactured by Imada Seisakusho Co., Ltd. The subsequent steps are the same as the method for measuring the average peel strength between the base material 11 and the laminate 20. As a result, the average value of the minimum peel strength among the peel strengths between each layer constituting the recording medium 10 can be determined.

[0103] [1.2 Method for Manufacturing Recording Media] The following describes an example of a method for manufacturing the recording medium 10 according to the first embodiment.

[0104] (First layered film formation process) First, the first color developer and the first matrix resin are dissolved and dispersed in a solvent (e.g., methyl ethyl ketone). Next, the first color-developing compound in a decolorized state and the first photothermal converter are added to this solution, thereby preparing the first color-developing layer forming coating. Subsequently, this first color-developing layer forming coating is applied onto the first film and dried. This yields a first laminated film consisting of the color-developing layer 22A and the first film.

[0105] (Second laminated film formation process) A second laminated film consisting of a color-developing layer 22B and a second film is obtained in the same manner as the first laminated film formation process, except that a second matrix resin, a second color-developing compound, a second color-developing agent, and a second photothermal converter are used instead of the first matrix resin, the first color-developing compound, the first color-developing agent, and the first photothermal converter.

[0106] (Third layered film formation process) A third laminated film consisting of a color-developing layer 22C and a third film is obtained in the same manner as the first laminated film formation process, except that a third matrix resin, a third color-developing compound, a third color-developing agent, and a third photothermal converter are used instead of the first matrix resin, the first color-developing compound, the first color-developing agent, and the first photothermal converter.

[0107] (Lamination process) First, a thermosetting resin is applied to the substrate 11 to form a coating film. Next, the first laminated film is placed on the coating film so that the color-developing layer 22A faces the coating film side. Then, the entire laminate is sandwiched between metal plates, or transported while sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls), and the coating film is heat-cured by heating and pressurizing. As a result, the substrate 11 and the color-developing layer 22A are bonded together by the adhesive layer 21A.

[0108] Next, a thermosetting resin is applied to the color-developing layer 22A to form a coating film. Then, the second laminated film is placed on the coating film with the color-developing layer 22B facing the coating film side. The entire laminate is then heated and pressurized by processes such as sandwiching it between metal plates or transporting it while sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls), thereby thermally curing the coating film. As a result, the color-developing layer 22A and the color-developing layer 22B are bonded together by the adhesive layer 21B.

[0109] Next, a thermosetting resin is applied to the color-developing layer 22B to form a coating film. Then, the third laminated film is placed on the coating film with the color-developing layer 22C facing the coating film side. The entire laminate is then heated and pressurized by processes such as sandwiching it between metal plates or transporting it while sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls), thereby thermally curing the coating film. As a result, the color-developing layer 22B and the color-developing layer 22C are bonded together by the adhesive layer 21C.

[0110] Next, a thermosetting resin is applied to the color-developing layer 22C to form a coating film. Then, the cover layer 13 is placed on the coating film, and the entire laminate is heated and pressurized by processes such as sandwiching it between metal plates or transporting it while sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls), thereby thermally curing the coating film. As a result, the color-developing layer 22C and the cover layer 13 are bonded together by the adhesive layer 12. The recording medium 10 shown in Figure 1 is obtained as a result of the above process.

[0111] [1.3 Recording Method for Recording Media] The following describes an example of a recording method for the recording medium 10 according to the first embodiment.

[0112] The color-developing layer 22A is colored magenta in the following manner. When near-infrared laser light with a peak wavelength λ1 is irradiated onto a predetermined location on the color-developing layer 22A, the first photothermal converter contained in the laser-irradiated area absorbs the near-infrared laser light and generates heat. This heat melts the first color developer, and a color reaction (color development reaction) occurs between the first color developer and the first color-developing compound, causing the laser-irradiated area to turn magenta.

[0113] The color-developing layer 22B is colored cyan as follows: When near-infrared laser light with a peak wavelength λ2 is irradiated onto a predetermined location on the color-developing layer 22B, the area irradiated by the laser light turns cyan due to a reaction similar to that of the color-developing layer 22A described above.

[0114] The color-developing layer 22C is colored yellow as follows: When near-infrared laser light with a peak wavelength λ3 is irradiated onto a predetermined position in the color-developing layer 22B, the area irradiated by the laser light turns yellow due to a reaction similar to that of the color-developing layer 22A described above.

[0115] As described above, the predetermined positions of the color-developing layers 22A, 22B, and 22C are color-developed in magenta, cyan, and yellow, respectively, thereby creating a desired full-color image on the recording medium 10A.

[0116] [1.4 Effects] As described above, in the recording medium 10 according to the first embodiment, the average peel strength between the substrate 11 and the laminate 20, the average peel strength between the color-developing layers 22 contained in the laminate 20, and the average peel strength between the laminate 20 and the cover layer 13 are 5 N / cm or more. This suppresses peeling between the substrate 11 and the laminate 20, peeling between the color-developing layers 22 contained in the laminate 20, and peeling between the laminate 20 and the cover layer 13, thereby ensuring excellent robustness. Thus, tampering with the recording medium 10 can be prevented, and the security of the recording medium 10 can be improved.

[0117] In the recording medium 10 according to the first embodiment, the color-developing layers 22A, 22B, and 22C are capable of exhibiting magenta, cyan, and yellow colors, respectively, in the color-developed state. Therefore, a desired image can be drawn in full color.

[0118] <2 Second Embodiment> [2.1 Recording medium configuration] Hereinafter, with reference to Figure 4, an example of the configuration of the recording medium 10A according to the second embodiment will be described. The recording medium 10A differs from the recording medium 10 according to the first embodiment in that it includes a laminate 20A instead of the laminate 20. The laminate 20A differs from the laminate 20 in the first embodiment in that it does not include an adhesive layer 21A and includes a base material (second base material) 23 instead of the adhesive layer 21C. In the second embodiment, the adhesive layer 21B included in the laminate 20 is an example of a fourth adhesive layer.

[0119] The substrate 11 has a first surface on which the laminate 20A is provided, and a second surface opposite to the first surface. The color-developing layer 22A is formed directly on the first surface of the substrate 11. By forming the color-developing layer 22A directly on the first surface of the substrate 11 in this way, the peel strength between the color-developing layer 22A and the substrate 11 can be increased compared to when the color-developing layer 22A is bonded to the first surface of the substrate 11 via an adhesive layer.

[0120] The substrate 23 is a support that supports the color-developing layers 22B and 22C. The substrate 23 may also serve as a heat insulating layer capable of insulating the space between the color-developing layer 22B and the color-developing layer 22C. Preferably, the substrate 23 is made of a material that has excellent heat resistance and excellent dimensional stability in the planar direction. The substrate 23 is transparent to laser light and visible light used for drawing on the recording medium 10A. The substrate 23 may be, for example, in the form of a plate or a film. The thickness of the substrate 23 is preferably 3 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less. If the thickness of the substrate 23 is less than 3 μm, there is a risk that sufficient heat insulating effect cannot be obtained as a heat insulating layer. On the other hand, if the thickness of the substrate 23 exceeds 100 μm, there is a risk that the transmittance to laser light and visible light used for drawing on the recording medium 10A will decrease. In addition, there is a risk that the bending resistance of the recording medium 10A will decrease, making it more susceptible to defects such as cracks.

[0121] The substrate 23 has a first surface to which laser light used for drawing the color-developing layer 22A or color-developing layer 22B is incident, and a second surface from which the laser light is emitted. The color-developing layer 22C is formed directly on the first surface of the substrate 23. By forming the color-developing layer 22C directly on the first surface of the substrate 23 in this way, the peel strength between the color-developing layer 22C and the substrate 23 can be increased compared to when the color-developing layer 22C is bonded to the first surface of the substrate 23 via an adhesive layer. The color-developing layer 22B is formed directly on the second surface of the substrate 23. By forming the color-developing layer 22B directly on the second surface of the substrate 23 in this way, the peel strength between the color-developing layer 22B and the substrate 23 can be increased compared to when the color-developing layer 22B is bonded to the second surface of the substrate 23 via an adhesive layer.

[0122] The base material 23 may be rigid or flexible. If a flexible base material 23 is used, a flexible recording medium 10A can be realized. Examples of rigid base materials 23 include wafers or glass substrates. Examples of flexible base materials 23 include flexible glass, film, or paper. The base material 23 may contain the same materials as the base material 11.

[0123] (Average peel strength) The average peel strength between the substrate 11 and the color-developing layer 22A, the average peel strength between the color-developing layer 22A and the color-developing layer 22B, the average peel strength between the color-developing layer 22B and the substrate 23, the average peel strength between the substrate 23 and the color-developing layer 22C, and the average peel strength between the color-developing layer 22C and the cover layer 13 are 5 N / cm or more, preferably 8 N / cm or more, more preferably 10 N / cm or more, and even more preferably 15 N / cm or more. As described above, when the peel strength between each layer is 5 N / cm or more, peeling between the substrate 11 and the color-developing layer 22A, peeling between the color-developing layer 22A and the color-developing layer 22B, peeling between the color-developing layer 22B and the substrate 23, peeling between the substrate 23 and the color-developing layer 22C, and peeling between the color-developing layer 22C and the cover layer 13 can be suppressed. Therefore, tampering with the recording medium 10A can be prevented.

[0124] The average peel strength between the substrate 11 and the coloring layer 22A, the average peel strength between the coloring layer 22A and the coloring layer 22B, the average peel strength between the coloring layer 22B and the substrate 23, the average peel strength between the substrate 23 and the coloring layer 22C, and the average peel strength between the coloring layer 22C and the cover layer 13 are determined in the same manner as the average peel strength between the substrate 11 and the laminate 20 in the first embodiment.

[0125] The average of the minimum peel strengths between each layer constituting the recording medium 10A is 5 N / cm or more, preferably 8 N / cm or more, more preferably 10 N / cm or more, and even more preferably 15 N / cm or more. As described above, when the average of the minimum peel strengths is 5 N / cm or more, peeling between each layer constituting the recording medium 10A can be suppressed. Therefore, tampering with the recording medium 10A can be prevented.

[0126] The average of the minimum peel strengths between each layer constituting the recording medium 10A is determined in the same manner as the average of the minimum peel strengths between each layer constituting the recording medium 10 in the first embodiment.

[0127] [2.2 Method for manufacturing recording media] The following describes an example of a method for manufacturing the recording medium 10A according to the second embodiment.

[0128] (First layer formation process) First, the first color developer and the first matrix resin are dissolved and dispersed in a solvent (e.g., methyl ethyl ketone). Next, the first color-developing compound in a decolorized state and the first photothermal converter are added to this solution and dispersed. This prepares the first color-developing layer forming coating. Subsequently, this first color-developing layer forming coating is applied to the first surface of the substrate 11 and dried to form the color-developing layer 22A. This yields the first laminate.

[0129] (Second layer formation process) First, the second color developer and the second matrix resin are dissolved and dispersed in a solvent (e.g., methyl ethyl ketone). Next, the second color-developing compound in a decolorized state and the second photothermal converter are added to this solution and dispersed. This prepares the second color-developing layer forming coating. Subsequently, if necessary, an easy-adhesion treatment such as plasma treatment is performed on the second surface of the substrate 23, and then the second color-developing layer forming coating is applied to the second surface of the substrate 23 and dried to form the color-developing layer 22B.

[0130] Next, the third color developer and the third matrix resin are dissolved and dispersed in a solvent (e.g., methyl ethyl ketone). Then, the third color-developing compound in a decolorized state and the third photothermal converter are added to this solution and dispersed. This yields a third color-developing layer forming coating. Subsequently, if necessary, an easy-adhesion treatment such as plasma treatment is performed on the first surface of the substrate 23, and then the third color-developing layer forming coating is applied to the first surface of the substrate 23 and dried to form the color-developing layer 22C. This yields a second laminate.

[0131] (Lamination process) First, a thermosetting resin is applied to the color-developing layer 22A of the first laminate to form a coating film. Next, the second laminate is placed on the coating film with the color-developing layer 22B facing the coating film side. Then, the entire laminate is sandwiched between metal plates, or transported while sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls), and the coating film is heat-cured by heating and pressurizing. As a result, the color-developing layer 22A and the color-developing layer 22B are bonded together by the adhesive layer 21B.

[0132] Next, a thermosetting resin is applied to the color-developing layer 22C to form a coating film. Then, the cover layer 13 is placed on the coating film, and the entire laminate is heated and pressurized by processes such as sandwiching it between metal plates or transporting it while sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls), thereby curing the coating film. As a result, the color-developing layer 22C and the cover layer 13 are bonded together by the adhesive layer 12. The recording medium 10A shown in Figure 4 is obtained as a result of the above process.

[0133] [2.3 Effects] In the second embodiment, the average peel strength between the substrate 11 and the coloring layer 22A, the average peel strength between the coloring layer 22A and the coloring layer 22B, the average peel strength between the coloring layer 22B and the substrate 23, the average peel strength between the substrate 23 and the coloring layer 22C, and the average peel strength between the coloring layer 22C and the cover layer 13 are 5 N / cm or more. This provides the same effects as in the first embodiment.

[0134] In the second embodiment, the color-developing layer 22A is formed directly on the first surface of the substrate 11, the color-developing layer 22C is formed directly on the first surface of the substrate 23, and the color-developing layer 22B is formed directly on the second surface of the substrate 23. This allows the number of adhesive layers 21 to be reduced compared to the laminate 20 according to the first embodiment. Therefore, the layer structure of the laminate 20A can be simplified compared to the laminate 20 according to the first embodiment.

[0135] <3 Third Embodiment> In the third embodiment, an example of a card equipped with the recording medium 10 according to the first embodiment or the recording medium 10A according to the second embodiment will be described.

[0136] [3.1 Card Composition] Hereinafter, an example of the configuration of a card 30 according to the third embodiment will be described with reference to Figures 5A and 5B. The card 30 comprises, in order, a base material (card base material) 31, an adhesive layer 32, an intermediate layer 33, an adhesive layer 34, and an overlay layer 35. The intermediate layer 33 includes a recording medium 36.

[0137] Card 30 is an ID card (e.g., employee ID, membership card, student ID, etc.). An ID card is an example of a card-type identification document. In the third embodiment, the case where card 30 is an ID card will be described, but the type of card on which the recording medium 36 is provided is not limited to this. The card on which the recording medium 36 is provided may be, for example, a security card, a financial settlement card (e.g., a credit card, cash card, etc.), a driver's license, a health insurance card, a basic resident register card, a My Number card (individual number card), or a personal transaction card (e.g., a prepaid card, a point card, etc.). Card 30 may also be a contactless IC card.

[0138] (Base material 31) The base material 31 is a support that supports the intermediate layer 33. The base material 31 has a rectangular, thin plate shape. The base material 31 has a first surface (front) on which the adhesive layer 32, intermediate layer 33, adhesive layer 34, and overlay layer 35 are laminated, and a second surface (back) opposite to the first surface. The base material 31 may have a color such as white. A design, picture, photograph, text, or a combination of two or more of these (hereinafter referred to as "design, etc.") may be printed on the first surface of the base material 31. The base material 31 may have an IC (integrated circuit) chip and an antenna coil, etc., on the first surface.

[0139] The base material 31 includes, for example, plastic. The base material 31 may optionally include at least one selected from the group consisting of colorants, antistatic agents, flame retardants, and surface modifiers.

[0140] The plastic includes, for example, at least one selected from the group consisting of ester resins, amide resins, olefin resins, vinyl resins, acrylic resins, imide resins, styrene resins, and engineering plastics. If the base material 31 contains two or more resins, these two or more resins may be mixed, copolymerized, or laminated.

[0141] Ester resins include, for example, at least one selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene terephthalate-isophthalate copolymer, and terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer. Amide resins include, for example, at least one selected from the group consisting of nylon 6, nylon 66, and nylon 610. Olefin resins include, for example, at least one selected from the group consisting of polyethylene (PE), polypropylene (PP), and polymethylpentene (PMP). Vinyl resins include, for example, polyvinyl chloride (PVC).

[0142] Acrylic resins include, for example, at least one selected from the group consisting of polyacrylate, polymethacrylate, and polymethyl methacrylate (PMMA). Imide resins include, for example, at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), and polyetherimide (PEI). Styrene resins include, for example, at least one selected from the group consisting of polystyrene (PS), high-impact polystyrene, acrylonitrile-styrene resin (AS resin), and acrylonitrile-butadiene-styrene resin (ABS resin). Engineering plastics include, for example, at least one selected from the group consisting of polycarbonate (PC), polyarylate (PAR), polysulfone (PSF), polyethersulfone (PES), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polyetherketone (PEK), polyether-etherketone (PEEK), polyphenylene oxide (PPO), and polyethersulfite.

[0143] (Middle class 33) The intermediate layer 33 is provided between the base material 31 and the overlay layer 35. More specifically, the intermediate layer 33 is provided on the first surface of the base material 31, and an adhesive layer 32 is sandwiched between the base material 31 and the intermediate layer 33. The intermediate layer 33 has a housing portion 33A for housing the recording medium 36. The housing portion 33A is provided in a part of the surface of the intermediate layer 33. The housing portion 33A may be a through hole that penetrates in the thickness direction of the intermediate layer 33. The intermediate layer 33 is intended to suppress the step difference formed by the recording medium 36 when the recording medium 36 is sandwiched between the base material 31 and the overlay layer 35. The intermediate layer 33 has approximately the same thickness as the recording medium 36 and covers the area of ​​the first surface of the base material 31 other than the area on which the recording medium 36 is provided.

[0144] The intermediate layer 33 has a film-like structure. The intermediate layer 33 may be transparent to visible light. The intermediate layer 33 contains plastic. Examples of plastic materials include those similar to those used for the base material 31.

[0145] (Overlay layer 35) The overlay layer 35 is provided on the intermediate layer 33 and the recording medium 36, and covers the intermediate layer 33 and the recording medium 36. An adhesive layer 34 is sandwiched between the intermediate layer 33, the recording medium 36 and the overlay layer 35. The overlay layer 35 protects the internal components of the card 30 (i.e., the recording medium 36 and the intermediate layer 33) and maintains the mechanical reliability of the card 30.

[0146] The overlay layer 35 has a film-like structure. The overlay layer 35 is transparent to visible light. The overlay layer 35 contains plastic. Examples of plastic materials include those similar to those used for the base material 31. A design or pattern may be printed on at least one surface of the overlay layer 35.

[0147] (Adhesive layer 32, 34) Adhesive layer 32 is provided between the substrate 31 and the intermediate layer 33, and adheres the substrate 31 and the intermediate layer 33. Adhesive layer 34 is provided between the intermediate layer 33 and the overlay layer 35, and adheres the intermediate layer 33 and the overlay layer 35. Adhesive layers 32 and 34 contain a thermosetting adhesive. The thermosetting adhesive contains a thermosetting resin. The thermosetting resin includes, for example, at least one selected from the group consisting of epoxy resins and urethane resins.

[0148] (Recording medium 36) The recording medium 36 is either the recording medium 10 according to the first embodiment or the recording medium 10A according to the second embodiment. The recording medium 36 is provided between the base material 31 and the overlay layer 35. The recording medium 36 is housed in the housing section 33A such that the base material 11 of the recording medium 36 faces the base material 31. A photograph of a face or the like is drawn on the recording medium 36. However, the information drawn on the recording medium 36 is not limited to a photograph of a face, but may also be security ID information or the like.

[0149] The recording medium 36 has a first surface facing the overlay layer 35 and a second surface facing the substrate 31. From the viewpoint of improving adhesion, it is preferable that the first surface and / or the second surface of the recording medium 36 be subjected to an easy-adhesion treatment such as plasma treatment. In this specification, "and / or" means at least one of the three, for example, "X and / or Y" means X only, Y only, or X and Y.

[0150] [3.2 Method for manufacturing cards] The following describes an example of a method for manufacturing the card 30 according to the third embodiment.

[0151] First, a thermosetting resin is applied to the first surface of the base material 31 as a thermosetting adhesive to form an adhesive layer 32. Next, an intermediate layer 33 is placed on the adhesive layer 32, and then the recording medium 36 is fitted into the housing portion 33A of the intermediate layer 33. Alternatively, the intermediate layer 33 with the recording medium 36 already fitted into the housing portion 33A may be placed on the adhesive layer 32. The adhesive layer 32 may also be formed by applying a thermosetting resin to the intermediate layer 33 with the recording medium 36 already fitted into the housing portion 33A, and then placing the intermediate layer 33 on the first surface of the base material 31 with the coating film in between. Alternatively, the adhesive layer 32 may be formed by bonding a sheet, which has been formed in advance by applying a thermosetting resin to a separator, to the first surface of the base material 31 or to the intermediate layer 33 with the recording medium 36 already fitted into the housing portion 33A by means of thermal lamination or the like.

[0152] Next, a thermosetting resin is applied to the intermediate layer 33 as a thermosetting adhesive to form an adhesive layer 34, and then an overlay layer 35 is placed on top of the adhesive layer 34. Next, the resulting laminate is sandwiched between metal plates and heated and pressurized to thermoset the adhesive layer 32 and adhesive layer 34. This yields the desired card 30. The adhesive layer 34 may also be formed by applying a thermosetting resin to the overlay layer 35 and then placing the overlay layer 35 on the intermediate layer 33 with the coating film in between. Alternatively, the adhesive layer 34 may be formed by bonding a sheet, which has been previously formed by applying a thermosetting resin to a separator, to the overlay layer 35 or the intermediate layer 33 by means of thermal lamination or the like.

[0153] [3.3 Effects] As described above, in the card 30 according to the third embodiment, the base material 31 and the intermediate layer 33 are bonded together by an adhesive layer 32 containing a thermosetting adhesive, and the intermediate layer 33 and the overlay layer 35 are bonded together by an adhesive layer 32 containing a thermosetting adhesive. This allows for strong bonding between the base material 31 and the intermediate layer 33, and between the intermediate layer 33 and the overlay layer 35. Therefore, tamper resistance can be improved.

[0154] Since the recording medium 36 is fitted into the housing portion 33A of the intermediate layer 33, it is possible to make it difficult to see the boundary between the recording medium 36 and the intermediate layer 33 in the in-plane direction of the card 30. Therefore, it becomes difficult to identify where on the plane of the card 30 the recording medium 36 is located. Thus, the tamper-proof properties can be improved. Since the recording medium 36 is enclosed inside the card 30, the effect of moisture on the recording medium 36 can be reduced.

[0155] <4. Fourth Embodiment> In the fourth embodiment, an example of a card having a different configuration from that of the third embodiment will be described.

[0156] [4.1 Card Composition] Hereinafter, with reference to Figure 6, an example of the configuration of card 30A according to the fourth embodiment will be described. Card 30A differs from card 30 according to the third embodiment in that it does not have adhesive layers 32 and 34, and the base material 31 and the intermediate layer 33 and the intermediate layer 33 and the overlay layer 35 are bonded together by fusion.

[0157] In the fourth embodiment, it is preferable that the base material 31, the intermediate layer 33, and the overlay layer 35 contain a thermoplastic resin as the plastic. By including a thermoplastic resin in the base material 31, the intermediate layer 33, and the overlay layer 35, the interlayer adhesion strength due to fusion can be strengthened. From the viewpoint of reducing damage to the recording medium 36, it is preferable that the thermoplastic resin is capable of heat-sealing the layers of the card 30A in a temperature range of 130°C to 200°C.

[0158] The base material 31, the intermediate layer 33, and the overlay layer 35 may contain the same type of thermoplastic resin, or they may not contain the same type of thermoplastic resin. If the base material 31, the intermediate layer 33, and the overlay layer 35 do not contain the same type of thermoplastic resin, one of the base material 31, the intermediate layer 33, and the overlay layer 35 may contain a different type of thermoplastic resin than the other two layers, or each of the base material 31, the intermediate layer 33, and the overlay layer 35 may contain different types of thermoplastic resins.

[0159] When the base material 31, intermediate layer 33, and overlay layer 35 contain the same type of thermoplastic resin, it is preferable that the base material 31, intermediate layer 33, and overlay layer 35 contain at least one selected from the group consisting of semicrystalline thermoplastic resins and amorphous thermoplastic resins, from the viewpoint of improving interlayer adhesion strength by fusion. The semicrystalline thermoplastic resin includes, for example, at least one selected from the group consisting of polypropylene (PP), polyethylene (PE), polyacetal (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK).

[0160] The amorphous thermoplastic resin includes, for example, at least one selected from the group consisting of ABS resin, polycarbonate (PC), polymer alloy of ABS resin and PC (hereinafter referred to as "ABS / PC polymer alloy"), AS resin, polystyrene (PS), polymethyl methacrylate (PMMA), polyphenylene oxide (PPO), polysulfone (PSU), polyvinyl chloride (PVC), polyetherimide (PEI), and polyethersulfone (PES).

[0161] If the base material 31, intermediate layer 33, and overlay layer 35 do not contain the same type of thermoplastic resin, it is preferable that the base material 31, intermediate layer 33, and overlay layer 35 contain an amorphous thermoplastic resin from the viewpoint of improving interlayer adhesion strength through fusion. Furthermore, it is conceivable that specific interfaces can be eliminated by thermal fusion, contributing to improved security.

[0162] The following combinations of amorphous thermoplastic resins are preferred for the two adjacent layers of card 30A. If one of the two adjacent layers of card 30A contains ABS resin, it is preferable that the other layer contains at least one selected from the group consisting of ABS / PC polymer alloy, polycarbonate (PC), AS resin, polystyrene (PS), polymethyl methacrylate (PMMA), and polyvinyl chloride (PVC).

[0163] If one of the two adjacent layers of card 30A contains an ABS / PC polymer alloy, it is preferable that the other layer contains at least one selected from the group consisting of ABS resin, polycarbonate (PC), and polymethyl methacrylate (PMMA). If one of the two adjacent layers of card 30A contains polycarbonate (PC), it is preferable that the other layer contains at least one selected from the group consisting of ABS resin, ABS / PC polymer alloy, and polymethyl methacrylate (PMMA).

[0164] If one of the two adjacent layers of card 30A contains AS resin, it is preferable that the other layer contains at least one selected from the group consisting of ABS resin, polystyrene (PS), polymethyl methacrylate (PMMA), and polyphenylene oxide (PPO).

[0165] If one of the two adjacent layers of card 30A contains polymethyl methacrylate (PMMA), it is preferable that the other layer contains at least one selected from the group consisting of ABS resin, ABS / PC polymer alloy, AS resin, and polyphenylene oxide (PPO). If one of the two adjacent layers of card 30A contains polyphenylene oxide (PPO), it is preferable that the other layer contains at least one selected from the group consisting of polycarbonate (PC), AS resin, polystyrene (PS), and polymethyl methacrylate (PMMA).

[0166] If one of the two adjacent layers of card 30A contains polysulfone (PSU), it is preferable that the other layer contains polycarbonate (PC). If one of the two adjacent layers of card 30A contains polyvinyl chloride (PVC), it is preferable that the other layer contains ABS resin.

[0167] [4.2 Method for manufacturing cards] The following describes an example of a method for manufacturing the card 30A according to the fourth embodiment.

[0168] First, an intermediate layer 33 is placed on the first surface of the base material 31, and then the recording medium 36 is fitted into the housing portion 33A of the intermediate layer 33. Alternatively, the intermediate layer 33 with the recording medium 36 already fitted into the housing portion 33A may be placed on the first surface of the base material 31. Next, an overlay layer 35 is placed on the intermediate layer 33. Then, the resulting laminate is sandwiched between metal plates and heated and pressurized to heat-seal the base material 31 and the intermediate layer 33, and the intermediate layer 33 and the overlay layer 35. The temperature applied to the laminate during heat sealing is preferably between 110°C and 200°C from the viewpoint of reducing damage to the recording medium 36 and achieving sufficient fusion strength. This yields the desired card 30A.

[0169] [4.3 Effects] As described above, in the card 30A according to the fourth embodiment, the base material 31 and the intermediate layer 33 and the intermediate layer 33 and the overlay layer 35 are fused together. Thereby, the base material 31 and the intermediate layer 33 and the intermediate layer 33 and the overlay layer 35 can be firmly bonded together. Therefore, the anti-counterfeiting property can be improved.

[0170] <5 Variation> (Variation 1) As shown in FIG. 7, the recording medium 10B according to Variation 1 is different from the recording medium 10A according to the second embodiment in that it includes a bonding layer 12A instead of the adhesive layer 12. The bonding layer 12A includes at least an adhesive layer. The bonding layer 12A may be a laminate including a film as a base material and adhesive layers provided on both surfaces of the film, or may be a single layer of an adhesive layer. Specifically, the bonding layer 12A may be, for example, a double-sided adhesive film such as an OCA (Optical Clear Adhesive). The adhesive layer contains an adhesive. The adhesive contains at least one selected from the group consisting of, for example, acrylic adhesives, urethane adhesives, and silicone adhesives. The adhesive layer may contain various additives such as an ultraviolet absorber.

[0171] Since the laminated body 20A and the cover layer 13 are bonded together by the bonding layer 12A, the peel strength between the laminated body 20A and the cover layer 13 can be made lower than the peel strength between the base material 11 and the laminated body 20A and the peel strength between the color developing layers 22 included in the laminated body 20A. Therefore, when an attempt is made to remove the recording medium 10B with a blade or the like for the purpose of counterfeiting, the laminated body 20A and the cover layer 13 are selectively peeled off, leaving traces of counterfeiting. Therefore, it can be determined visually or the like that an attempt has been made to remove the recording medium 10B for the purpose of counterfeiting.

[0172] It is preferable that the average peel strength between the laminate 20A and the cover layer 13 is 4 N / cm or less. When the average peel strength between the laminate 20A and the cover layer 13 is 4 N / cm or less, when an attempt is made to take out the recording medium 10B with a blade or the like for the purpose of forgery, it is possible to selectively make it easier to peel between the laminate 20A and the cover layer 13.

[0173] The average peel strength between the laminate 20A and the cover layer 13 is determined in the same manner as the average peel strength between the base material 11 and the laminate 20 in the first embodiment.

[0174] In the above description, the example in which the recording medium 10B according to the first modification includes the laminate 20A has been described. However, the recording medium 10B according to the first modification may include the laminate 20 in the first embodiment instead of the laminate 20A.

[0175] (Second modification) As shown in FIG. 8, the recording medium 10C according to the second modification is different from the recording medium 10A according to the second embodiment in that it includes a brittle layer 12B instead of the adhesive layer 12. When an attempt is made to take out the recording medium 10C for the purpose of forgery, the brittle layer 12B is broken. For this reason, it becomes difficult to reattach the cover layer 13. Further, the breakage of the brittle layer 12B is preferably cohesive failure. When the breakage of the brittle layer 12B is cohesive failure, light is scattered on the peeling surface, so that the peeling surface becomes whitened. Therefore, it is possible to easily determine by visual inspection or the like that an attempt has been made to forge the recording medium 10A.

[0176] The brittle layer 12B includes, for example, a film as a base material and adhesive layers provided on both surfaces of the film. The film includes, for example, at least one selected from the group consisting of a polyvinyl chloride film and a polypropylene film.

[0177] In the above description, the example in which the recording medium 10B according to the second modification includes the laminate 20A has been described. However, the recording medium 10B according to the second modification may include the laminate 20 in the first embodiment instead of the laminate 20A.

[0178] (Variation 3) As shown in Figure 9, the recording medium 10D according to Modification 3 differs from the recording medium 10 according to the first embodiment in that it includes a laminate 20B instead of the laminate 20. The laminate 20B differs from the laminate 20 in the first embodiment in that it further includes an adhesive layer 21D and a functional layer 24. The adhesive layer 21D and the functional layer 24 are laminated on the color-developing layer 22C in this order.

[0179] The functional layer 24 includes, for example, at least one selected from the group consisting of a UV-cutting layer and a hologram layer. The adhesive layer 21D may be the same as the adhesive layer 21A.

[0180] The average peel strength between the functional layer 24 and the color-developing layer 22C is preferably 5 N / cm or more, more preferably 8 N / cm or more, even more preferably 10 N / cm or more, and particularly preferably 15 N / cm or more. As described above, when the average peel strength between the functional layer 24 and the color-developing layer 22C is 5 N / cm or more, peeling between the functional layer 24 and the color-developing layer 22C can be suppressed. Therefore, tampering with the recording medium 10D can be prevented.

[0181] The average peel strength between the functional layer 24 and the cover layer 13 is preferably 5 N / cm or more, more preferably 8 N / cm or more, even more preferably 10 N / cm or more, and particularly preferably 15 N / cm or more. As described above, when the average peel strength between the functional layer 24 and the cover layer 13 is 5 N / cm or more, peeling between the functional layer 24 and the cover layer 13 can be suppressed. Therefore, tampering with the recording medium 10D can be prevented.

[0182] In the above description, an example was given in which the laminate 20A further comprises an adhesive layer 21D and a functional layer 24, but the laminate 20B may further comprise the adhesive layer 21D and the functional layer 24.

[0183] In the above description, an example was given in which the functional layer 24 is provided on the color-developing layer 22C. However, the stacking position of the functional layer 24 within the recording medium 10D is not limited to this example. For example, it may be provided between the substrate 11 and the color-developing layer 22A, between the color-developing layer 22A and the color-developing layer 22B, or between the color-developing layer 22B and the color-developing layer 22C.

[0184] In the above description, an example was given in which the recording medium 10D has a single functional layer 24, but the recording medium 10D may have two or more functional layers 24. In this case, the two or more functional layers 24 may be arranged adjacent to each other, or they may be arranged with one or more color-developing layers 22 in between.

[0185] (Modification 4) As shown in Figure 10, the recording medium 10E according to Modification 4 differs from the recording medium 10 according to the first embodiment in that it further comprises a side cover 14. The side cover 14 covers the edges of the base material 11, the laminate 20, the adhesive layer 12, and the cover layer 13. Here, the edges refer to the portion between the peripheral edges of both main surfaces of the base material 11, the laminate 20, the adhesive layer 12, and the cover layer 13. The side cover 14 contains, for example, an ultraviolet-curable resin. The side cover 14 may also contain various additives, such as an ultraviolet absorber.

[0186] The recording medium 10E is equipped with a side cover 14, which prevents moisture and other substances from entering the recording medium 10E from its edges.

[0187] (Variation 5) In the first and second embodiments, examples were described in which the recording media 10 and 10A have three color-developing layers 22A, 22B, and 22C. However, the recording media 10 and 10A may also have multiple color-developing layers other than three (i.e., two color-developing layers or four or more color-developing layers). In this case as well, adhesive layers or substrates may be provided between the color-developing layers. Each of the multiple color-developing layers may exhibit a different hue from the others in the color-developed state. That is, the color-developing compounds contained in each of the multiple color-developing layers may exhibit a different hue from the others in the color-developed state. The photothermal converters contained in each of the multiple color-developing layers may have different absorption wavelength peaks from each other.

[0188] (Experimental variation 6) In the first and second embodiments, examples were described in which the recording media 10 and 10A include an adhesive layer 12 and a cover layer 13, but they do not necessarily have to include an adhesive layer 12 and a cover layer 13.

[0189] (Example 7) In the first and second embodiments, examples were described in which objects to be bonded are bonded together by applying a thermosetting resin to the objects to be bonded (for example, the substrate 11, the coloring layer 22A, the coloring layer 22B, and the coloring layer 22C) and then heat-curing it. However, the manufacturing method of the recording media 10 and 10A is not limited to these. For example, instead of applying a thermosetting resin to the objects to be bonded, a thermosetting adhesive sheet may be sandwiched between the objects to be bonded, and these may be heated to bond them together.

[0190] (Variation 8) In the third embodiment, an example was described in which the adhesive layer 32, the intermediate layer 33, the adhesive layer 34, and the overlay layer 35 are sequentially laminated on the first surface of the substrate 31. However, the adhesive layer 32, the intermediate layer 33, the adhesive layer 34, and the overlay layer 35 may also be sequentially laminated on the second surface of the substrate 31. Alternatively, the adhesive layer 32, the intermediate layer 33, the adhesive layer 34, and the overlay layer 35 may be sequentially laminated on the second surface instead of the first surface.

[0191] In the fourth embodiment, an example in which the intermediate layer 33 and the overlay layer 35 are sequentially laminated on the first surface of the base material 31 has been described. However, the intermediate layer 33 and the overlay layer 35 may also be sequentially laminated on the second surface of the base material 31. Alternatively, the intermediate layer 33 and the overlay layer 35 may be sequentially laminated on the second surface instead of the first surface.

[0192] (Modified Example 9) In the third embodiment, an example in which the card 30 includes the recording medium 36 in a partial region of the first surface of the base material 31 has been described. However, as shown in FIG. 11A, the card 30 may include the recording medium 36 in substantially the entire region of the first surface of the base material 31. Specifically, the card 30 may include a recording medium 36 having substantially the same size as the base material 31 between the adhesive layer 32 and the adhesive layer 34. Similarly, the card 30A may include the recording medium 36 in substantially the entire region of the first surface of the base material 31. Specifically, the card 30A may include a recording medium 36 having substantially the same size as the base material 31 between the base material 31 and the overlay layer 35. The first surface of the recording medium 36 may be subjected to a release treatment. When the first surface of the recording medium 36 is subjected to a release treatment, if an attempt is made to remove the recording medium 36 with a blade or the like for the purpose of forgery, the space between the recording medium 36 and the overlay layer 35 is selectively peeled off, making it difficult to remove the recording medium 36. The second surface of the recording medium 36 may also be subjected to a release treatment.

[0193] (Modified Example 10) In Modified Example 9, an example in which the card 30 includes the adhesive layer 34 and the overlay layer � has been described. However, as shown in FIG. 11B, the card 30 may not include the adhesive layer 34 and the overlay layer 35. Similarly, the card 30A may not include the overlay layer 35.

[0194] (Modified Example 11) In Modification 10, an example was described in which the card 30 has an adhesive layer 32 and a recording medium 36 on the front surface (first surface) of the base material 31. However, as shown in Figure 11C, the card 30 may have an adhesive layer 32 and a recording medium 36 on the back surface (second surface) of the base material 31. In this case, the recording medium 36 may be provided on the back surface (second surface) of the base material 31 such that the base material 11 of the recording medium 36 faces the base material 31. Similarly, the card 30A may have a recording medium 36 on the back surface (second surface) of the base material 31.

[0195] (Example 12) In the first and second embodiments, an example was described in which the housing portion 33A is a through-hole penetrating in the thickness direction of the intermediate layer 33. However, the housing portion 33A may also be a bottomed recess that is recessed in the thickness direction of the intermediate layer 33. In this case, the recess may be provided on the first surface of the intermediate layer 33 facing the overlay layer 35, or on the second surface facing the base material 31.

[0196] (Example 13) In the third and fourth embodiments, examples of cards 30 and 30A equipped with the recording medium 10 according to the first embodiment or the recording medium 10A according to the second embodiment were described, but the recording medium 10 or the recording medium 10A may be provided in a booklet.

[0197] Figure 12 is a perspective view showing an example of the configuration of a booklet 40 according to Modification 13. The booklet 40 is a passport. A passport is an example of a booklet-type identification document. The booklet 40 comprises a plurality of sheets 41. The plurality of sheets 41 are saddle-stitched. A recording medium 42 is provided on at least one or both sides of a sheet 41. A photograph or the like is drawn on the recording medium 42. The recording medium 42 is the recording medium 10 according to the first embodiment or the recording medium 10A according to the second embodiment. The sheet 41 may have a layer configuration similar to that of the card 30 according to the third embodiment or the card 30A according to the fourth embodiment. In this case, the base material may be paper or the like.

[0198] (Variation 14) The above recording media 10, 10A, 10B, 10C, 10D, and 10E may be incorporated into medical supplies, automotive parts, automobiles, toys, food products, cosmetics, clothing, documents, exterior components, or electronic devices (e.g., electronic device casings). Specific examples of exterior components include, for example, the interior or exterior of building walls, or the exterior of furniture such as desks. Specific examples of electronic devices include personal computers (hereinafter referred to as "PCs"), mobile devices, mobile phones (e.g., smartphones), tablet computers, display devices, cameras, audio equipment, game consoles, industrial equipment, medical equipment, robots, or wearable devices. Specific examples of wearable devices include watches, bags, clothing, hats, glasses, or shoes. Two or more of the above recording media 10, 10A, 10B, 10C, 10D, and 10E may be combined and incorporated into the above-mentioned products.

[0199] (Other variations) While embodiments and modifications of the present disclosure have been described in detail above, the present disclosure is not limited to the embodiments and modifications described above, and various modifications based on the technical idea of ​​the present disclosure are possible.

[0200] For example, the configurations, methods, processes, shapes, materials, and numerical values ​​listed in the above embodiments and modifications are merely examples, and different configurations, methods, processes, shapes, materials, and numerical values ​​may be used as needed.

[0201] The configurations, methods, processes, shapes, materials, and numerical values ​​of the above embodiments and modified examples can be combined with each other without departing from the spirit of this disclosure.

[0202] In the numerical ranges described stepwise in the above embodiments and modifications, the upper or lower limit of a numerical range in one step may be replaced with the upper or lower limit of a numerical range in another step.

[0203] Unless otherwise specified, the materials illustrated in the above embodiments and modifications can be used individually or in combination of two or more.

[0204] Furthermore, this disclosure may also adopt the following configuration. (1) The first substrate and The laminate provided on the first substrate and Equipped with, The laminate includes a plurality of color-developing layers, A recording medium wherein the average peel strength between the first substrate and the laminate, and the average peel strength between the color-developing layers contained in the laminate, are 5 N / cm or more. (2) The recording medium according to (1), wherein the plurality of color-developing layers include an electron-donating color-developing compound and an electron-accepting color developer. (3) The laminate further comprises a plurality of adhesive layers, The plurality of color-developing layers include a first color-developing layer, a second color-developing layer, and a third color-developing layer. The plurality of adhesive layers include a first adhesive layer, a second adhesive layer, and a third adhesive layer. The recording medium according to (1) or (2), wherein the first adhesive layer, the first color-developing layer, the second adhesive layer, the second color-developing layer, the third adhesive layer, and the third color-developing layer are laminated on the first substrate in this order. (4) The recording medium according to (3), wherein the first adhesive layer, the second adhesive layer, and the third adhesive layer each contain a thermosetting resin. (5) The laminate further comprises a fourth adhesive layer and a second substrate, The plurality of color-developing layers include a first color-developing layer, a second color-developing layer, and a third color-developing layer. The first color-developing layer, the fourth adhesive layer, the second color-developing layer, the second substrate, and the third color-developing layer are laminated on the first substrate in this order. The recording medium according to (1) or (2), wherein the average peel strength between the second coloring layer and the second substrate, and the average peel strength between the third coloring layer and the second substrate are 5 N / cm or more. (6) The recording medium according to (5), wherein the fourth adhesive layer comprises a thermosetting resin. (7) A fifth adhesive layer provided on the laminate and A cover layer provided on the fifth adhesive layer and Furthermore, The recording medium according to any one of (1) to (6), wherein the average peel strength between the laminate and the cover layer is 5 N / cm or more. (8) A laminating layer provided on the laminate and A cover layer provided on the aforementioned laminated layer and Furthermore, The recording medium according to any one of (1) to (6), wherein the average peel strength between the laminate and the cover layer is 4 N / cm or less. (9) A brittle layer provided on the aforementioned laminate and A cover layer provided on the brittle layer and A recording medium according to any one of (1) to (6), further comprising the above. (10) The laminate further includes a functional layer, The recording medium according to any one of (1) to (9), wherein the average peel strength between the functional layer and the color-developing layer is 5 N / cm or more. (11) The recording medium according to any one of (1) to (10), further comprising a cover that covers the first substrate and the ends of the laminate. (12) The recording medium according to any one of (1) to (11), wherein the average peel strength between the first substrate and the laminate, and the average peel strength between the color-developing layers contained in the laminate, is 8 N / cm or more. (13) The recording medium according to any one of (1) to (11), wherein the average peel strength between the first substrate and the laminate, and the average peel strength between the color-developing layers contained in the laminate, is 10 N / cm or more. (14) The first substrate and The laminate provided on the first substrate and Equipped with, The laminate includes a plurality of color-developing layers, A recording medium in which the average of the minimum peel strengths between each layer constituting the recording medium is 5 N / cm or more. (15) A card equipped with a recording medium as described in any one of items (1) to (14). (16) The card substrate further comprises a first surface and a second surface, The recording medium is the card described in (15) provided on the first surface and / or the second surface. (17) With an additional overlay layer, The recording medium is the card described in (16) provided between the card substrate and the overlay layer. (18) It further includes an intermediate layer and an overlay layer, The card according to (16), wherein the intermediate layer is provided between the card substrate and the overlay layer and has a housing portion for housing the recording medium. (19) A booklet comprising a recording medium as described in any one of items (1) to (14). [Examples]

[0205] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to these examples.

[0206] [Example 1] (First layered film formation process) First, a bis(hydroxybenzoic acid) type compound (first color developer) and polycarbonate (first matrix resin) were dissolved and dispersed in methyl ethyl ketone (MEK). Next, a leuco dye that exhibits a magenta color in the colored state (first color-developing compound) and a photothermal conversion material having an absorption wavelength peak in the near-infrared region and a phthalocyanine skeleton (first photothermal conversion material) were added to this solution to prepare a first color-developing layer forming coating. Subsequently, this first color-developing layer forming coating was applied to the first film and dried. This resulted in a first laminated film consisting of the first color-developing layer and the first film.

[0207] (Second laminated film formation process) As the second coloring compound, a leuco dye that exhibits a cyan color in the colored state was used. Furthermore, as the second photothermal conversion agent, a photothermal conversion material having a different absorption wavelength peak in the near-infrared region than the first photothermal conversion agent and having a phthalocyanine skeleton was used. Except for these, the process was the same as that for forming the first laminated film to obtain a second laminated film consisting of a second coloring layer and a second film.

[0208] (Third layered film formation process) As the third coloring compound, a leuco dye that exhibits a yellow color in the colored state was used. Furthermore, as the third photothermal conversion agent, a photothermal conversion material having a different absorption wavelength peak in the near-infrared region than the first and second photothermal conversion agents and having a phthalocyanine skeleton was used. Aside from these, the third laminated film consisting of a third coloring layer and a third film was obtained in the same manner as the formation process of the first laminated film.

[0209] (Lamination process) First, an epoxy adhesive, acting as a thermosetting resin, was applied to a PET film substrate to a thickness of 5 μm or more to form a coating. This thermosetting resin may be laminated by heating and pressing, for example, by sandwiching a sheet between metal plates or by transporting it sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls). Next, the first laminated film was placed on the coating so that the first color-developing layer faced the coating side. Then, the entire laminate was sandwiched between metal plates and the coating was heat-cured by heating and pressing. As a result, the substrate and the first color-developing layer were bonded together by the first adhesive layer (thermosetting resin layer).

[0210] Next, an epoxy adhesive, acting as a thermosetting resin, was applied to the first color-developing layer to a thickness of 5 μm or more to form a coating film. This thermosetting resin may be laminated by heating and pressing, for example, by sandwiching a sheet between metal plates or by transporting it sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls). Next, the second laminated film was placed on the coating film with the second color-developing layer facing the coating film side. Then, the entire laminate was sandwiched between metal plates and the coating film was heat-cured by heating and pressing. As a result, the first color-developing layer and the second color-developing layer were bonded together by the second adhesive layer (thermosetting resin layer).

[0211] Next, an epoxy adhesive, acting as a thermosetting resin, was applied to the second color-developing layer to a thickness of 5 μm or more to form a coating film. This thermosetting resin may be laminated by heating and pressing, for example, by sandwiching a sheet between metal plates, or by transporting it while sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls). Next, the third laminated film was placed on the coating film with the third color-developing layer facing the coating film side, and the entire laminate was sandwiched between metal plates and the coating film was heat-cured by heating and pressing. As a result, the second color-developing layer and the third color-developing layer were bonded together by the third adhesive layer (thermosetting resin layer).

[0212] Next, an epoxy adhesive, acting as a thermosetting resin, was applied to the third color-developing layer to a thickness of 5 μm or more to form a coating film. This thermosetting resin may be laminated by heating and pressing, for example, by sandwiching a sheet between metal plates, or by transporting it while sandwiched between metal rolls (e.g., SUS rolls) and rubber rolls (e.g., heat-resistant silicone rolls). Next, a PET film as a cover layer was placed on the coating film, and the entire laminate was sandwiched between metal plates and the coating film was heat-cured by heating and pressing. As a result, the third color-developing layer and the cover layer were bonded together by the fifth adhesive layer (thermosetting resin layer). Thus, a recording medium was obtained.

[0213] [Example 2] First, a first color-developing layer was formed on one side of a PET film (thermoplastic resin sheet) as the substrate by coating. This obtained the first laminate. Next, a second color-developing layer and a third color-developing layer were formed on both sides of the PET film (thermoplastic resin sheet) as the substrate by coating. This obtained the second laminate. The thermoplastic resin sheet is not limited to PET film; any sheet that is resistant to the solvent to which it is coated may be selected as appropriate. Next, a thermosetting resin was applied to the first color-developing layer of the first laminate to a thickness of 5 μm or more to form a coating film. Next, the second laminate was placed on the coating film with the second color-developing layer facing the coating film side, and the entire laminate was sandwiched between metal plates and the coating film was heat-cured by heating and applying pressure. As a result, the first color-developing layer and the second color-developing layer were bonded together by a fourth adhesive layer (thermosetting resin layer). A recording medium was obtained in the same manner as in Example 1, except for these steps.

[0214] [Example 3] In the lamination process, an acrylic thermosetting adhesive sheet was formed on the third color-developing layer. Next, a PET film as a cover layer was placed on the adhesive layer, and the entire laminate was sandwiched between metal plates and heated while being pressurized. As a result, the third color-developing layer and the cover layer were bonded together by the fifth adhesive layer. The recording medium was obtained in the same manner as in Example 1, except for these steps.

[0215] [Comparative Example 1] An epoxy adhesive was applied to a thickness of approximately 2 μm as the thermosetting resin to form the first, second, third, and fifth adhesive layers (thermosetting resin layers), thereby forming a coating film. The recording medium was obtained in the same manner as in Example 1.

[0216] [Evaluation of peel strength] Using the recording media of Examples 1 to 3 and Comparative Example 1 obtained as described above, the average peel strength between the substrate and the first color-developing layer (between the substrate and the laminate), the average peel strength between the first color-developing layer and the second color-developing layer, the average peel strength between the second color-developing layer and the third color-developing layer, and the average peel strength between the third color-developing layer and the cover layer (between the laminate and the cover layer) were measured. The results are shown in Table 1. The method for measuring the average peel strength described in the first embodiment was used.

[0217] Figure 13A shows a graph obtained from a 90-degree peel test between the substrate and the first coloring layer in Example 1. Figure 13B shows a graph obtained from a 90-degree peel test between the substrate and the first coloring layer in Example 2. Figure 14A shows a graph obtained from a 90-degree peel test between the third coloring layer and the cover layer in Example 3. Figure 14B shows a graph obtained from a 90-degree peel test between the substrate and the first coloring layer in Comparative Example 1.

[0218] [Table 1] [Explanation of symbols]

[0219] 10, 10A, 10B, 10C, 10D, 10E, 36, 42 Recording media 11, 23, 31 Base material 12, 21A, 21B, 21C, 21D, 32, 34 Adhesive layer 12A Lamination layer 12B Brittle layer 13. Cover layer 14 Side Covers 30, 30A card 33 Middle Class 33A Storage area 35 Overlay Layers 40 booklets 41 sheets

Claims

1. The first substrate and A laminate provided on the first substrate, A bonding layer provided on the laminate, A cover layer provided on the aforementioned laminated layer and Equipped with, The laminate includes a plurality of color-developing layers, The average peel strength between the first substrate and the laminate, and the average peel strength between the color-developing layers contained in the laminate, are 5 N / cm or more. A recording medium wherein the average peel strength between the laminate and the cover layer is 4 N / cm or less.

2. The recording medium according to claim 1, wherein the plurality of color-developing layers include an electron-donating color-developing compound and an electron-accepting color developer.

3. The laminate further comprises a plurality of adhesive layers, The plurality of color-developing layers include a first color-developing layer, a second color-developing layer, and a third color-developing layer. The plurality of adhesive layers include a first adhesive layer, a second adhesive layer, and a third adhesive layer. The recording medium according to claim 1, wherein the first adhesive layer, the first color-developing layer, the second adhesive layer, the second color-developing layer, the third adhesive layer, and the third color-developing layer are laminated on the first substrate in this order.

4. The recording medium according to claim 3, wherein the first adhesive layer, the second adhesive layer, and the third adhesive layer each contain a thermosetting resin.

5. The laminate further comprises a fourth adhesive layer and a second substrate, The plurality of color-developing layers include a first color-developing layer, a second color-developing layer, and a third color-developing layer. The first color-developing layer, the fourth adhesive layer, the second color-developing layer, the second substrate, and the third color-developing layer are laminated on the first substrate in this order. The recording medium according to claim 1, wherein the average peel strength between the second color-developing layer and the second substrate, and the average peel strength between the third color-developing layer and the second substrate are 5 N / cm or more.

6. The recording medium according to claim 5, wherein the fourth adhesive layer comprises a thermosetting resin.

7. The laminate further includes a functional layer, The recording medium according to claim 1, wherein the average peel strength between the functional layer and the color-developing layer is 5 N / cm or more.

8. The recording medium according to claim 7, wherein the functional layer includes at least one of a UV-cutting layer and a hologram layer.

9. The recording medium according to claim 1, further comprising a cover that covers the ends of the first substrate and the laminate.

10. The recording medium according to claim 1, wherein the average peel strength between the first substrate and the laminate, and the average peel strength between the color-developing layers contained in the laminate, is 8 N / cm or more.

11. The recording medium according to claim 1, wherein the average peel strength between the first substrate and the laminate, and the average peel strength between the color-developing layers contained in the laminate, is 10 N / cm or more.

12. A card comprising the recording medium described in claim 1.

13. The card substrate further comprises a first surface and a second surface, The card according to claim 12, wherein the recording medium is provided on the first surface and / or the second surface.

14. With an additional overlay layer, The card according to claim 13, wherein the recording medium is provided between the card substrate and the overlay layer.

15. It further includes an intermediate layer and an overlay layer, The card according to claim 13, wherein the intermediate layer is provided between the card substrate and the overlay layer and has a housing portion for housing the recording medium.

16. The card according to any one of claims 12 to 15, wherein the card is an ID card, a security card, a financial settlement card, a driver's license, a health insurance card, a basic resident register card, a personal number card, or a personal transaction card.

17. A booklet comprising the recording medium described in any one of claims 1 to 11.

18. An electronic device comprising a recording medium according to any one of claims 1 to 11.

19. A passport comprising the recording medium described in any one of claims 1 to 11.

20. A wearable terminal comprising the recording medium described in any one of claims 1 to 11.