Recording medium

Abstract

To provide a recording medium in which clarity of black in the case of radiating a laser beam onto a laminate is excellent, and a height difference of information images formed by laser irradiation does not occur.SOLUTION: A recording medium comprises: a first laser coloring layer which contains a material that changes into first hue of shades of black or a material that changes into second hue different from the first hue by laser beam irradiation; a second laser coloring layer having light permeability which contains a material that changes into the first hue by laser beam irradiation; and a third laser coloring layer having light permeability which contains a material that changes into the second hue by laser beam irradiation and consists of the same thickness as the second laser coloring layer, where the second laser coloring layer and the third laser coloring layer are adjacently laminated on the first laser coloring layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a recording medium having a laser coloring layer laminated thereon. [Background technology]

[0002] In recent years, card substrates have become widespread, and various kinds of cards are used in daily life. For example, there are cards with specific information printed on the surface of a plastic substrate, magnetic cards such as telephone cards, IC cards such as credit cards with built-in IC memory, and passports using data pages with personal information printed on a plastic substrate, on which images such as a face photo are printed for identification purposes.

[0003] One method for preventing tampering with such various cards is to irradiate a laser onto a recording medium having a laser coloring layer laminated thereon, thereby recording personal information such as a color image of a face.

[0004] As an example of the aforementioned recording medium, there is disclosed a laminate comprising a substrate, an intermediate layer having a storage section with a color-developing layer containing a color-developing compound having electron-donating properties, a color-developing agent having electron-accepting properties, and a matrix resin, and an overlay layer provided on the intermediate layer, and capable of forming a color image by color development of the color-developing compound by laser irradiation (see, for example, Patent Document 1).

[0005] Patent document 2 discloses a recording medium having a thermosensitive coloring layer and a monochrome coloring layer, in which the thermosensitive coloring layer has three colors, C (cyan), M (magenta), and Y (yellow), and the monochrome coloring layer is disposed so as to surround the thermosensitive recording layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2022 / 138766 publication [Patent Document 2] Utility model registration No. 3221579 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although the technology of Patent Document 1 is a useful technology that produces the color components C (cyan), M (magenta), and Y (yellow) by irradiating laser light, the production of black is achieved by subtractive color mixing of C (cyan), M (magenta), and Y (yellow), and therefore there is a problem in that the black color lacks vividness.

[0008] FIG. 5(a) is a plan view of the laminate described in Patent Document 1, and FIG. 5(b) is a cross-sectional view taken along line AA' thereof. As shown in FIG. 5(b), in a recording medium (B1) in which the laminate described in Patent Document 1 is laminated as a third laser coloring layer (3) on a first laser coloring layer (1), and a light-transmitting resin layer (6) is laminated on the first laser coloring layer (1) adjacent to the third laser coloring layer (3), the position where the information image is formed differs in the thickness direction of the laminate of the first laser coloring layer (1) and the third laser coloring layer (3), and a difference occurs in the focal length of the laser light, so that the third information image (5) recorded on the third laser coloring layer (3) appears to stand out from the first information image (7) recorded on the first laser coloring layer (1).

[0009] Although the technology of Patent Document 2 solves the problem of images appearing to float by adjusting the focal length of the laser light to the same distance for both the thermosensitive coloring layer and the monochrome coloring layer, the thermosensitive coloring layer still has the problem of lack of vividness of the black color in the thermosensitive coloring layer, since it uses C (cyan), M (magenta), and Y (yellow).

[0010] The present invention solves the above-mentioned problems by providing a recording medium which has good black color clarity when laser light is irradiated onto the laminate and which does not result in height differences between information images formed by irradiation with laser light. [Means for solving the problem]

[0011] The present invention is a recording medium comprising a first laser coloring layer containing a material that changes to a first hue of black or a material that changes to a second hue different from the first hue when irradiated with laser light, a second laser coloring layer that contains a material that changes to the first hue when irradiated with laser light and has optical transparency, and a third laser coloring layer that contains a material that changes to the second hue when irradiated with laser light and has the same thickness as the second laser coloring layer and has optical transparency, characterized in that the second laser coloring layer and the third laser coloring layer are stacked adjacent to each other on the first laser coloring layer. Effect of the Invention

[0012] The present invention can provide a recording medium with good black clarity by mixing a monochromatic black with the subtractive black of C (cyan), M (magenta), and Y (yellow) in an information image formed by irradiation with laser light.

[0013] Furthermore, the present invention can provide a recording medium in which no difference in height occurs between information images formed by irradiation with a laser beam. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a diagram showing an example of a recording medium according to the present invention. [Diagram 2] FIG. 1 is a diagram showing an example of the effect of a recording medium according to the present invention. [Diagram 3] FIG. 1 is a diagram showing an example of the effect of a recording medium according to the present invention. [Figure 4] FIG. 1 is a diagram showing an example of the effect of a recording medium according to the present invention. [Diagram 5] FIG. 1 is a diagram showing an example of a conventional recording medium. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The following describes an embodiment of the present invention with reference to the drawings. However, the present invention is not limited to the embodiment described below, and includes various other embodiments within the scope of the technical idea described in the claims.

[0016] (Embodiment) The recording medium (A1) is shown in Fig. 1. The recording medium (A1) in this embodiment is composed of a first laser coloring layer (1), a second laser coloring layer (2) and a third laser coloring layer (3) having the same thickness as the second laser coloring layer (2) laminated adjacent to and in parallel on the first laser coloring layer (1).

[0017] The thickness of the first laser coloring layer (1) is not particularly limited. When it is made into a card shape, the JIS standard for identification cards (JIS X 6301:2005) stipulates that the thickness should be 0.76 mm, so the total thickness of the final product should be within this range.

[0018] The thicknesses of the second laser coloring layer (2) and the third laser coloring layer (3) are not particularly limited, as is the first laser coloring layer (1), and may be in accordance with the JIS standard for identification cards (JIS X 6301:2005) described above. In addition, the thicknesses of the second laser coloring layer (2) and the third laser coloring layer (3) may be different from or the same as the first laser coloring layer (1).

[0019] The reason for making the second laser coloring layer (2) and the third laser coloring layer (3) the same thickness is that by recording the information images (4, 5) at the same position in the thickness direction of the second laser coloring layer (2) and the third laser coloring layer (3), no steps will be generated on the surface when a protective layer or a different laser coloring layer is further laminated on the laser coloring layers (2, 3), so there is no risk of affecting product quality when processing by pressing, etc.

[0020] In addition, the second laser coloring layer (2) and the third laser coloring layer (3) are formed adjacent to each other because, for example, if there is a gap between the second laser coloring layer (2) and the third laser coloring layer (3), the coloring of the first laser coloring layer (1) would adversely affect the visibility of the information image drawn on the second laser coloring layer (2) and the third laser coloring layer (3).

[0021] The second laser coloring layer (2) and the third laser coloring layer (3) may be formed adjacent to each other, and adjacent means that the second laser coloring layer (2) and the third laser coloring layer (3) are arranged in close contact with each other without any gaps.

[0022] The method for forming the second laser coloring layer (2) and the third laser coloring layer (3) on the first laser coloring layer (1) is not particularly limited, and may be performed by laminating them according to the melting or adhesive properties of the thermoplastic resin, such as welding by heating using laser heating, high frequency heating, hot plate heating, vibration heating, ultrasonic heating, etc., a bonding method by mixing an adhesive and a curing agent, or a bonding method by applying pressure at room temperature after applying an adhesive.

[0023] (First laser coloring layer) The first laser coloring layer (1) shown in FIG. 1 contains a material having an absorption characteristic for a first laser beam having a wavelength in the infrared region of 700 nm to 2000 nm, which is a first wavelength region, or a absorption characteristic for a second laser beam having a wavelength in the ultraviolet region of 350 to 370 nm or a wavelength in the visible light region of 380 to 780 nm, which is a second wavelength region different from the first wavelength region.

[0024] The first laser coloring layer (1) changes to a first hue of blackish color when irradiated with the first laser beam, or changes to a second hue different from blackish color when irradiated with the first or second laser beam. As will be described later, when the first laser coloring layer (1) changes to the first hue, the third laser coloring layer (3) changes to the second hue. When the first laser coloring layer (1) changes to the second hue, the third laser coloring layer (3) changes to the first hue.

[0025] When the first laser coloring layer (1) contains a material that has an absorption characteristic in the first laser light having a wavelength in the infrared region of 700 nm to 2000 nm, which is the first wavelength region, the material that has an absorption characteristic in the infrared region includes known inks or infrared coloring thermoplastic resin sheets that contain carbon, diphosphorus pentoxide (P2O5), iron oxide, glass-based powder of copper oxide, cesium tungsten oxide compounds, etc., or a material or thermoplastic resin layer that contains a decolorized electron donor dye, a thermal acid generator, and a photothermal conversion agent.

[0026] The thermoplastic resin layer is composed of a single layer or a laminate of multiple thermoplastic resin layers. As the thermoplastic resin, known thermoplastic resin sheets such as polycarbonate (PC), polyethylene terephthalate glycol (PETG), polyvinyl chloride (PVC), and acrylonitrile-butadiene styrene copolymer resin (ABS resin) can be used.

[0027] (Electron donor dye) The electron donating dye is a compound capable of exhibiting a reversible or irreversible hue change under the action of an acid and a base. That is, the electron donating dye in a decolorized state can change its structure and develop a color under the action of an acid. The electron donating dye is, for example, a leuco dye. When a lactone ring contained in the leuco dye reacts with an acid, the lactone ring opens and develops a color, and when the open lactone ring reacts with a base, the lactone ring closes and decolorizes. The leuco dye may be, for example, an existing dye for thermal paper.

[0028] The electron donating dye is not particularly limited and can be appropriately selected depending on the purpose. Examples of the electron donating dye include fluoran compounds, triphenylmethanephthalide compounds, azaphthalide compounds, phenothiazine compounds, leucoauramine compounds, and indolinophthalide compounds.

[0029] (Thermal acid generator) The thermal acid generator is a so-called color developer, and generates an acid at a predetermined temperature or higher. When the generated acid acts on the electron-donating dye in a decolorized state, the structure of the electron-donating dye changes and develops color. The thermal acid generator is, for example, an onium salt. The onium salt preferably contains at least one selected from the group consisting of ammonium salts, sulfonium salts, and iodonium salts. The acid generation temperatures of the ammonium salts, sulfonium salts, and iodonium salts are all within the range of 150° C. or higher and lower than 280° C. The anions of the ammonium salts, sulfonium salts, and iodonium salts include, for example, compounds containing sulfur, phosphorus, boron, or antimony.

[0030] (Photothermal conversion agent) The photothermal conversion agent absorbs light in the infrared region of 700 nm to 2000 nm to generate heat, and is preferably a material that has an absorption peak in the range of 700 nm to 2000 nm and has almost no absorption in the visible region.Specific examples include at least one selected from the group consisting of compounds having a phthalocyanine skeleton (phthalocyanine dyes), compounds having a squarylium skeleton (squarylium dyes), and inorganic compounds.

[0031] Examples of inorganic compounds include 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, metal oxides such as tricobalt tetroxide, iron oxide, chromium oxide, copper oxide, titanium black, ITO (indium tin oxide), metal nitrides such as niobium nitride, metal carbides such as tantalum carbide, metal sulfides, and various magnetic powders, etc. In addition, compounds having a cyanine skeleton (cyanine dyes) having excellent light resistance and heat resistance may be used.

[0032] When the first laser coloring layer (1) contains a material having an absorption characteristic in the second laser light having a wavelength in the ultraviolet region of 350 to 370 nm, which is the second wavelength region, or a wavelength in the visible light region of 380 to 780 nm, examples of the material having an absorption characteristic in the ultraviolet region include ink or resin sheets containing titanium dioxide (white titanium), which is one of titanium oxide compounds, and indoline spiropyran (3',3'-dimethyl-1-isopropyl-8-methoxy-6-nitrospiro (2H-1-benzopyran-2,2-indoline)). Also, examples of the material having an absorption characteristic in the visible light region wavelength include known pigments and dyes having absorption characteristics according to colors such as red, green, and blue.

[0033] The color of the first laser coloring layer (1) itself is not particularly limited as long as it does not affect the coloring of the second laser coloring layer (2) and the third laser coloring layer (3) described later, and may be transparent, white, or other colored. For example, a resin sheet such as a white polycarbonate (PC) containing titanium dioxide (white titanium), which is one of the titanium oxide compounds, or an IR (infrared) laser coloring sheet containing carbon and having a light transmitting (transparent or semi-transparent) infrared absorbing property may be mentioned.

[0034] (Second laser coloring layer) The second laser coloring layer (2) shown in FIG. 1 contains a material having an absorption characteristic for a first laser beam having a wavelength in the infrared region of 700 nm to 2000 nm, which is a first wavelength region, or contains a material having an absorption characteristic for a second laser beam having a wavelength in the ultraviolet region of 350 to 370 nm or a visible light region of 380 to 780 nm, which is a second wavelength region different from the first wavelength region.

[0035] When the second laser coloring layer (2) contains a material that has an absorption characteristic in the first laser light having a wavelength in the infrared region of 700 nm to 2000 nm, which is the first wavelength region, the material that has an absorption characteristic in the infrared region includes known inks or infrared coloring thermoplastic resin sheets that contain carbon, diphosphorus pentoxide (P2O5), iron oxide, glass-based powder of copper oxide, cesium tungsten oxide compounds, etc., or a material or thermoplastic resin layer that contains a decolorized electron donor dye, a thermal acid generator, and a photothermal conversion agent.

[0036] The second laser coloring layer (2) must have light transmittance. The reason why the second laser coloring layer (2) is required to have light transmittance is to visually recognize the first information image recorded in the first laser coloring layer (1). Note that light transmittance does not mean that light is completely transmitted, but it is sufficient that the laser light for expressing the first information image (7) in the first laser coloring layer (1) can transmit.

[0037] The second laser coloring layer (2) is not particularly limited as long as it is a thermoplastic resin layer having optical transparency, and is configured by laminating a single layer or multiple thermoplastic resin layers. As the optically transparent thermoplastic resin layer, known thermoplastic resin sheets such as polycarbonate (PC), polyethylene terephthalate glycol (PETG), polyvinyl chloride (PVC), acrylonitrile-butadiene styrene copolymer resin (ABS resin), etc. can be used.

[0038] The second laser coloring layer (2) changes to a first hue of blackish color by irradiation with the first laser beam or the second laser beam. When the first laser coloring layer (1) changes to a first hue of blackish color or a second hue different from blackish color, the second laser coloring layer (2) has the first hue of blackish color, so that the black color of the second information image (4) can be made clear.

[0039] (Third laser coloring layer) The third laser coloring layer (3) shown in FIG. 1 contains a material having an absorption characteristic for a first laser beam having a wavelength in the infrared region of 700 nm to 2000 nm, which is a first wavelength region, or contains a material having an absorption characteristic for a second laser beam having a wavelength in the ultraviolet region of 350 to 370 nm or a visible light region of 380 to 780 nm, which is a second wavelength region different from the first wavelength region.

[0040] As with the first laser coloring layer (1) described above, when the third laser coloring layer (3) contains a material that has an absorption characteristic for the first laser light having a wavelength in the infrared region of 700 nm to 2000 nm, which is the first wavelength region, examples of the material include known inks or infrared coloring thermoplastic resin sheets containing carbon, diphosphorus pentoxide (P2O5), iron oxide, glass-based powder of copper oxide, cesium tungsten oxide compounds, etc., or a material or thermoplastic resin layer containing an electron donating dye in a decolorized state, a thermal acid generator, and a photothermal conversion agent.

[0041] The third laser coloring layer (3) is not particularly limited as long as it is a thermoplastic resin layer having optical transparency, and is configured by laminating a single layer or multiple thermoplastic resin layers. As the optically transparent thermoplastic resin layer, known thermoplastic resin sheets such as polycarbonate (PC), polyethylene terephthalate glycol (PETG), polyvinyl chloride (PVC), acrylonitrile-butadiene styrene copolymer resin (ABS resin), etc. can be used.

[0042] When the third laser coloring layer (3) changes to a first hue of black by the laser beam, the first laser coloring layer (1) becomes a second hue different from black. When the third laser coloring layer (3) changes to a second hue different from black by the laser beam, the first laser coloring layer (1) becomes a first hue of black. By making one of the first laser coloring layer (1) and the third laser coloring layer (3) a first hue of black and the other a second hue different from black, the black color of the third information image (5) described later can be made clearer.

[0043] Next, the first hue and the second hue of each laser coloring layer will be described.

[0044] (First Hue) The first hue formed by the first laser beam is blackish. The blackish hue may be any hue in the blackish range, and includes not only black but also gray hues close to black. The first hue is formed by absorbing infrared rays from the IR (infrared) laser, which is the first laser beam, and developing a blackish color. The first hue may be either reversible or irreversible, and is not particularly limited. In order to prevent the recorded information from being erased, it is preferable that the first hue is irreversible. Furthermore, for example, when the second hue formed by the laser beam of the third laser coloring layer (3) is black formed by subtractive color mixing of C (cyan), M (magenta), and Y (yellow), the mixture of the black of the first hue and the second hue results in a clear (high contrast) black color.

[0045] (Second Hue) The second hue formed by the first laser light or the second laser light may be a color similar to or different from the first hue, and may be any one of C (cyan), M (magenta), Y (yellow), R (red), G (green) or B (blue), or a combination thereof, or black formed by subtractive color mixing, but is not limited to these colors. The second hue is formed by absorbing the infrared rays of the IR (infrared) laser, which is the first laser light, or the ultraviolet rays and visible rays of the second laser light, and developing a color other than black or black by subtractive color mixing. The second hue is not particularly limited as long as it is reversible or irreversible like the first hue. In addition, it is preferable that the second hue is irreversible in order to prevent the recorded information from being erased.

[0046] Next, FIG. 2 shows an example of a recording medium (A1) of the present invention in which a second information image (4) is formed on the second laser color-producing layer (2) and a third information image (5) is formed on the third laser color-producing layer (3).

[0047] As shown in FIG. 2, by making the second laser coloring layer (2) and the third laser coloring layer (3) the same thickness, it is possible to adjust the focus of the laser light to a position where the third laser coloring layer (3) and the second laser coloring layer (2) are the same thickness.

[0048] Therefore, by making the second laser coloring layer (2) and the third laser coloring layer (3) the same thickness, the focus of the laser light can be made to be the same at the formation positions of the second information image (4) and the third information image (5), thereby preventing the occurrence of height differences between the information images (4, 5).

[0049] Also, as shown in Fig. 3, the second information image (4) and the third information image (5) may be formed adjacent to each other to form a single image, the fourth information image (8). Or, as shown in Fig. 4, when the third information image (5) including the second hue of black by subtractive color mixing is formed on the top layer of the first information image (7) consisting of a first hue of black, the black color of the third information image (5) becomes clear by the mixture of the black color of the first hue and the second hue.

[0050] In the plan views of Figures 2, 3 and 4, the third laser coloring layer (3) on the surface is rectangular, but the shape and position are not particularly limited, and the second information image (4) and the third information image (5) are facial images, but the present invention may also be formed using not only facial images, but also characters, figures, symbols, etc.

[0051] In addition, a thermoplastic resin sheet such as the polycarbonate described above or an additional laser coloring layer may be laminated on the recording medium of the present invention, printing may be applied to the thermoplastic resin sheet or the additional laser coloring layer, or a hologram or the like may be attached between the layers. [Explanation of symbols]

[0052] A1 Recording medium B1 Conventional recording media 1. First laser coloring layer 2 Second laser coloring layer 3. Third laser coloring layer 4. Second Infographic 5. Third Infographic 6 Transparent resin layer 7 First Infographic 8. Fourth Infographic

Claims

[Claim 1] a first laser coloring layer containing a material that changes to a first hue of black or a material that changes to a second hue different from the first hue when irradiated with a laser beam; a second laser coloring layer containing a material that changes to the first hue upon irradiation with the laser light and having optical transparency; A recording medium comprising a third laser coloring layer having the same thickness as the second laser coloring layer and having optical transparency, the third laser coloring layer containing a material that changes to the second hue when irradiated with the laser light, 1. A recording medium comprising: said second laser coloring layer and said third laser coloring layer laminated adjacent to each other on said first laser coloring layer.

Images