Information recording medium

Abstract

To provide an information recording body for a booklet such as a passport and a visa that require a high security property and a credit card, which has a high counterfeit prevention effect and has an image whose authenticity is easy to determine and to provide a heat-sensitive transfer medium provided for the manufacturing thereof.SOLUTION: The information recording body is formed by laminating the following each comprised of a plastic sheet in this order: the first protective layer; a laser color development layer; a core layer; the second protective layer; and an overlay layer. The overlay layer includes the first security pattern whose image is formed by at least infrared permeation ink on demand, and the image obtained by overlapping the first pattern and the second security pattern where image is formed on the laser color development layer on demand by laser engraving can display different security pattern information depending on observation angles. And also a heat-sensitive transfer medium is provided for the manufacturing of the information recording body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an information recording medium and a heat-sensitive transfer medium having an image with high anti-counterfeiting effect, in the form of an information recording medium such as a booklet or card, including a passport or visa. [Background technology]

[0002] 2. Description of the Related Art Various security methods have been proposed to protect personal information stored on information recording media related to personal authentication, such as passports, visa stickers, and ID cards.

[0003] For example, according to current passport regulations and ICAO (International Civil Aviation Organization) regulations, passports must be readable both visually and by optical character recognition, but the materials and security used are left to the discretion of each country.

[0004] Commonly used security features include chemical reactants that react with organic solvents, iridescent pearl chips, fibers (silk or synthetic, visible or invisible, fluorescent or non-fluorescent), security threads made of film printed with holograms or micro-characters, paper incorporating watermarks, and various inks such as fade-resistant ink, fluorescent ink, heat-sensitive ink, and optically variable ink (so-called OVI), as well as various techniques such as fine line printing, rainbow printing, intaglio printing, and pixel printing, all of which aim to simultaneously improve security and aesthetics.

[0005] Traditionally, the facial photograph used as visual identification information on passports was a pasted-on photograph, but in recent years there has been a trend to digitize the photographic information and form an image on the passport. Methods being considered for forming images on passports include thermal transfer recording using transfer ribbons such as resin-type melting types with dispersed pigments, wax-type melting types, and dye sublimation and diffusion types, as well as electrophotography and inkjet methods.

[0006] Known image display media containing this type of personal authentication data include those that have an image pattern formed based on image data on a substrate such as polyvinyl chloride or polycarbonate, those that have an image pattern on a paper substrate, and even those that have a hologram or diffraction grating in addition to the above image pattern.

[0007] Methods are being considered for including multiple pieces of information to identify an individual in addition to a facial photograph. For example, there is a method for authenticating a person by including digital watermark information in the facial photograph, storing that information on an IC chip in the same medium, and comparing the digital watermark information with the information on the IC chip (see Patent Document 1 below).

[0008] There is also a method of digitizing the feature points of facial photograph information, converting the value into a two-dimensional code, printing it on the same medium, and then matching the two-dimensional code data with the feature points of the facial photograph to perform authentication (Patent Document 2 listed below).

[0009] However, the technologies of Patent Documents 2 and 3 listed below require a dedicated device and decoder to read the information on the IC chip or the two-dimensional code, which limits the situations in which authentication can be performed.

[0010] Another possible verification method is to include multiple facial photographs that can be authenticated by visual information, and in addition to the facial photograph provided by the above method, there is a method of forming an identical facial photograph using fluorescent material (Patent Documents 3, 4, and 5 listed below).

[0011] However, these methods using fluorescent materials require the use of an ultraviolet lamp (black light), so the situations in which they can be used for authentication are limited.

[0012] An example of a method for forming a hologram or diffraction grating in addition to an image pattern such as a facial photograph is an image formation method using an intermediate transfer method in which an intermediate transfer medium having a hologram layer is used as an image receiving sheet on which an image pattern such as a facial photograph is formed (Patent Document 6 below).

[0013] Such hologram or diffraction grating transfer foils function satisfactorily to prevent counterfeiting. However, because the hologram or diffraction grating transfer layer is thermally transferred onto an image such as a face photograph after it has been formed, as in the case of passports, with the advances in counterfeiting technology today, it is possible that an attacker could remove the transfer layer by some method, tamper with the image data, etc., and then reapply the transfer foil.

[0014] To solve this problem, a technology has been proposed in which a concealing pattern is applied under the optical element, and then a pattern is formed using two of the colors yellow (Y), magenta (M), and cyan (C), to create a moiré pattern with color changes that can be seen (Patent Document 7 below).

[0015] However, the technology of Patent Document 7 below requires the hidden pattern to be visually recognized via an optical element from the side opposite to the side on which the image is printed, which makes the authentication procedure complicated. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-126046 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-70532 [Patent Document 3] Japanese Patent Application Publication No. 7-125403 [Patent Document 4] Japanese Patent Application Laid-Open No. 2000-141863 [Patent Document 5] Japanese Patent Application Laid-Open No. 2002-226740 [Patent Document 6] Japanese Patent Application Publication No. 6-106740 [Patent Document 7] Japanese Patent Publication No. 2019-142083 Summary of the Invention [Problem to be solved by the invention]

[0017] Therefore, the present invention has been made to address the above-mentioned problems, and provides a method for preventing counterfeiting and having an image that is easy to identify as authentic in information recording media such as booklets and cards, including passports and visas, which require high security. Provide information records The purpose is to: [Means for solving the problem]

[0018] As a means for solving the above-mentioned problems, the invention described in claim 1 is an information recording medium comprising a first protective layer, a laser coloring layer, a core layer, a second protective layer, and an overlay layer, each of which is made of a plastic sheet, laminated in this order, wherein the overlay layer contains at least a first security pattern formed on demand using an infrared transmitting ink, First security symbol The information recording medium is capable of displaying different security pattern information depending on the observation angle by superimposing a second security pattern image formed on demand by laser engraving on the laser coloring layer.

[0019] A second aspect of the present invention is the information recording medium according to the first aspect, characterized in that the security image information, which varies depending on the observation angle, is visualized by a moire pattern.

[0020] The invention described in claim 3 is characterized in that the overlay layer is laminated by adhering an intermediate transfer foil including a pattern formed by a thermal transfer method to the second protective layer. Claim 1 or 2 The information recording medium is described in [Effects of the Invention]

[0023] According to the present invention, different images can be displayed simply by changing the angle at which the information recording medium is observed, and the authenticity of the information recording medium can be easily confirmed.

[0024] Furthermore, according to the present invention, both the first image formed with infrared-transmitting ink and the second image formed by laser engraving can be formed on demand, making it possible to mass-produce individually unique information recording media without the need for printing plates.

[0025] Furthermore, according to the present invention, since the first image can be produced in a single color using an infrared-transmitting ink panel, the formation of the detailed image required for moire generation can be easily performed without the need for precise alignment that would be required in the case of multiple colors.

[0026] Furthermore, according to the present invention, when the second pattern is formed directly below the first pattern by laser engraving, the quality of the laser engraving is not affected because the first pattern is made of infrared-transparent ink.

[0027] Furthermore, according to the present invention, the overlay image including the first image can be formed using conventional thermal transfer equipment without requiring special image forming equipment for security purposes.

[0028] Furthermore, according to the present invention, the pattern for verifying authenticity is not an image of a single layer, but is only revealed by combining images of different layers formed by two different methods, so that an information recording medium that is extremely difficult to alter or counterfeit can be provided. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic diagram illustrating an example of a heat-sensitive transfer medium in an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an example of a printer that issues an information recording medium of the present invention. [Figure 3] FIG. 1 is a schematic diagram of an example of an information recording medium issued in accordance with the present invention. [Figure 4] 1 is a cross-sectional view of an information recording medium according to an embodiment of the present invention taken along line AA'. [Figure 5]1 is a cross-sectional view showing an example of the positions of patterns 1 and 2 and the viewing angle in an embodiment of the present invention. [Figure 6] 1A and 1B are schematic diagrams showing an example of image changes in a security image (moire image) when an information recording medium in an embodiment of the present invention is tilted. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described in detail. In the following description, drawings will be referred to as appropriate, but the embodiments shown in the drawings are merely examples of the present invention, and the present invention is not limited to the embodiments shown in these drawings.

[0031] In addition, all components that perform the same or similar functions are given the same reference numerals throughout the drawings, and duplicated explanations will be omitted.

[0032] (thermal transfer media) FIG. 1 is a perspective view of a heat-sensitive transfer medium according to one embodiment of the present invention. The thermal transfer medium 1 shown in Fig. 1 has a band shape. In Fig. 1, the thermal transfer medium 1 is in the form of a roll with one end unwound. The thermal transfer medium 1 may have other shapes.

[0033] The thermal transfer medium 1 includes a support 2, ink panels K, C, M, and Y that serve as colorant layers, an infrared-absorbing ink panel S that serves as a security layer, and a primer ink panel P that serves as an adhesive layer. Fluorescent panels and photoluminescent panels may be added as needed.

[0034] The support 2 has a strip shape, but may have other shapes. The support 2 has sufficient resistance to heat during transfer. The support 2 is, for example, a polymer film such as a polyethylene terephthalate film. The support 2 may have a single-layer structure or a multi-layer structure.

[0035] The ink panels K, C, M, Y, S, and P are provided on one main surface of the support 2. More specifically, on the main surface of the support 2, a plurality of ink panel groups, each consisting of ink panels K, C, M, Y, S, and P, are arranged in the in-plane direction, in this case, the longitudinal direction of the support 2. In each ink panel group, the ink panels K, C, M, Y, S, and P are arranged in the in-plane direction. In this case, in each ink panel group, the ink panels K, C, M, Y, S, and P are arranged in this order in the longitudinal direction of the support 2. Furthermore, in this case, the ink panels K, C, M, Y, S, and P each have a band shape extending in the width direction of the support 2.

[0036] The ink panels K, C, M, and Y, which are the hue panels, are black, cyan, magenta, and yellow, respectively. Each of the ink panels K, C, M, and Y is made of thermal transfer ink. Here, the thermal transfer ink is a color ink containing a color material and a binder resin. The color material contained in the ink panels K, C, M, and Y is one or more pigments, one or more dyes, or a combination thereof. The color inks constituting the ink panel K, the color inks constituting the ink panel C, the color inks constituting the ink panel M, and the color inks constituting the ink panel Y exhibit black, cyan, magenta, and yellow, respectively, when illuminated with white light.

[0037] The infrared transparent ink used in the ink panel S is generally a mixture of process colors, cyan, magenta, and yellow pigments, to produce black. Other than these, bisbenzofuran pigments, azomethine pigments, perylene pigments, azo dyes, and bismuth sulfide pigments can also be used.

[0038] The binder used in each hue panel and ink panel S can be any substantially transparent thermoplastic resin, such as, but not limited to, acrylic resin, urethane resin, styrene resin, polyester resin, epoxy resin, vinyl resin, rosin resin, polyolefin resin, and polyamide resin. Each thermoplastic resin can be used alone or as a mixture, or as a composite such as a copolymer. Fillers such as silica, talc, and calcium carbonate, as well as waxes, may also be added.

[0039] The thermoplastic resin used in the ink panel P may be any material that bonds the transfer foil to the base material (plastic) of the information recording medium, and examples thereof include, but are not limited to, acrylic resins, urethane resins, polyester resins, vinyl resins such as vinyl chloride and vinyl acetate, polyolefin resins such as polyethylene and polypropylene, and various derivatives and copolymers thereof. Furthermore, the various resins may be used alone or in mixtures or composites of two or more resins. Furthermore, in addition to indestructible fillers such as silica, talc, and calcium carbonate, and organic fillers, waxes may also be added.

[0040] The dimensions of each of the ink panels K, C, M, Y, S and P can be set appropriately, for example, to match the dimensions of the recording area on the recording medium to which the thermal transfer ink is to be transferred from the thermal transfer medium 1.

[0041] The thermal transfer medium 1 may further have a backcoat layer such as a heat-resistant layer and a lubricating layer on the side of the support 2 opposite to the ink panels K, C, M, Y, S and P.

[0042] (Intermediate transfer foil) The intermediate transfer foil must have at least an image-receiving layer to be transferred from the thermal transfer medium 1, but if necessary, a release layer, anchor layer, hologram-forming layer, etc. may be laminated, and a backcoat layer may be formed on the support on the side opposite the image-receiving layer. Resin films such as polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate, acrylic resin, polypropylene, and triacetyl cellulose can be used as the support.

[0043] Examples of materials for the image-receiving layer include, but are not limited to, polyester resins such as linear saturated polyesters, vinyl chloride resins such as polyvinyl chloride and polyvinyl chloride-vinyl acetate copolymers, vinyl resins such as polyacrylic acid, poly2-methoxyethyl acrylate, polymethyl acrylate, polyacrylonitrile, polymethyl chloroacrylate, polymethyl methacrylate, polyethyl methacrylate, polytert-butyl methacrylate, polyisobutyl methacrylate, polyphenyl methacrylate, methyl methacrylate, and alkyl methacrylate (wherein the alkyl group has 2 to 6 carbon atoms), polystyrene resins, polydivicrylbenzene, polyvinylbenzene, styrene-butadiene copolymers, urethane resins, and epoxy resins. These resins may be used alone or as a composite, such as a mixture or laminate of two or more types, and various additives such as ultraviolet absorbers and fillers may also be added.

[0044] The release layer preferably has peelability and tearability when heated, and also functions to prevent external chemical and mechanical damage after transfer to the transfer recipient (substrate). Examples of suitable resins include, but are not limited to, thermoplastic acrylic resins, cellulose-based resins, and chlorinated polypropylene resins. These resins may be used alone or as composites such as mixtures or laminates of two or more types. They may also contain fluororesin powders and polyethylene powders. Anti-friction agents and inorganic substances, such as animal waxes, vegetable waxes, fatty alcohol and acid waxes, amine and amide waxes, chlorinated conversion waxes, and metal salts of higher fatty acids such as zinc stearate, may also be added.

[0045] The anchor layer can be provided as needed, and can be provided as an OVD (Optical Variable Device) layer having a security image such as a hologram or a diffraction grating.

[0046] (Information recording media excluding transfer foil) The first protective layer, laser coloring layer, core layer, and second protective layer that make up the information recording medium (hereinafter referred to as the information recording medium substrate) before the transfer foil is adhered may be made of, but are not necessarily limited to, plastic resins such as vinyl chloride resin, polycarbonate resin, polyester resin such as polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer resin, acrylic resin, and polyolefin resin such as polypropylene resin. Furthermore, it is preferable to use the same substrate for each layer, as this will make the information recording medium more uniform and more durable when thermocompression bonded.

[0047] The laser coloring layer may be made of a polycarbonate resin that is carbonized by irradiation with a laser beam, or a resin similar to that of the core sheet or protective sheet, with a laser coloring agent mixed in. The thickness of each layer is preferably 50 μm or more and 200 μm or less for the protective layer, 50 μm or more and 600 μm or less for the core layer, and 20 μm or more and 200 μm or less for the laser coloring layer.

[0048] The laser light is assumed to be a YAG laser, a YVO4 laser (1064 nm), or a CO2 laser (10600 nm).

[0049] (Method of creating information recording medium) FIG. 2 is a diagram showing an example of an indirect transfer recording device that can be used to manufacture an information recording medium.

[0050] The information recording medium according to the embodiment of the present invention can be manufactured using the above-described thermal transfer medium 1 and a thermal transfer printer. Figure 2 shows an example in which the thermal transfer printer is configured with a primary transfer unit 101, which is an indirect transfer type printer.

[0051] 2, the thermal transfer medium 1 is unwound from a thermal transfer medium unwinding unit 3, passes between a thermal head 5 and a platen roller 10 in a primary transfer unit 101 where thermal transfer printing is performed on an intermediate transfer foil 6, and is then taken up by a thermal transfer medium take-up unit 4. The intermediate transfer foil 6 is also unwound from an unwinding roll 7, passes between the thermal head 5 and the platen roller 10 in the primary transfer unit 101, then passes between a heat roller 9 and the platen roller 10 in a secondary transfer unit 102 where thermal and pressure transfer is performed on a recording medium 11, which is a transfer recipient, and is then taken up by an intermediate transfer foil take-up unit 8.

[0052] In the primary transfer unit 101, a color image, character pattern, etc. are transferred from the four ink panels K, C, M, and Y (black, cyan, magenta, and yellow) from the thermal transfer medium 1 onto the overlay layer, which also serves as the image-receiving layer of the intermediate transfer foil 6, and a first security pattern is transferred from the infrared-transparent ink panel S. Furthermore, an adhesive layer is transferred from the primer ink panel P.

[0053] The intermediate transfer foil 6 on which each pattern is formed is transported to the secondary transfer section 102 and heat-pressed onto the information recording material substrate 11 by the heat roller 9, whereby each pattern formed in the primary transfer section 101 is transferred together with the overlay layer to the information recording material substrate 11, and an information recording material 12 is formed.

[0054] In this way, color images, patterns such as characters, and glitter patterns can be formed in any shape and arrangement by appropriately controlling the operation of the thermal head 5. Therefore, any individual information can be recorded on the intermediate transfer foil 6 and the information recording medium 12.

[0055] Furthermore, although not shown here, a second security pattern is formed on the laser coloring layer by selectively irradiating the information recording medium 12 with laser light from the intermediate transfer foil side.

[0056] (Information recording body) FIG. 3 is a plan view showing an example of the information recording medium 12 obtained as described above. In Figure 3, the personal information printing area of ​​the information recording medium 12 is provided with a first image 13 consisting of a facial photograph image, a second image 14 which is also a facial photograph image but with the first security pattern and the second security pattern superimposed, and a character string 15 consisting of character information such as name, date of birth, personal number, etc.

[0057] Figure 4 is a cross-sectional view taken along line A-A' in Figure 3. The first image 13 is formed as a color image by combining ink panels C, M, and Y, and the character string 15 is formed as a monochrome image by ink panel K, both of which are formed on the intermediate transfer foil 6. These are then adhesively laminated onto the first protective layer 21 via a primer layer P as an overlay 16.

[0058] The second image 14 is shown to be formed as a first security pattern 14-P1 by ink panel S in the same layer as the aforementioned C, M, Y, and K, and as a second security pattern 14-P2 formed by laser engraving in the laser coloring sheet 21. The first security pattern 14-P1 and the second security pattern 14-P2 are separated by a distance h that is the sum of the thicknesses of the first protective layer 21 and the core layer 19.

[0059] The distance h, i.e., the distance between the first security pattern 14-P1 and the second security pattern 14-P2 that generate the security information as a moire pattern, must be equal to or greater than the pattern pitch, and is preferably equal to or greater than 100 μm. The greater the distance between the first security pattern 14-P1 and the second security pattern 14-P2, the more dynamic the movement of the moire image when the information recording medium 12 is tilted, improving visibility.

[0060] The base material of the information recording medium 12 may be entirely transparent (transparent plastic card) or transparent only in the area where the second image 14 is located (windowed plastic card). It is preferable to have a symmetrical thickness structure to reduce warping of the plastic card.

[0061] The first security pattern 14-P1 formed by the security panel S is one of the moiré images. The first security pattern 14-P1 may or may not be a straight line. The pattern pitch of the first security pattern 14-P1 only needs to be narrower than the distance h between the first security pattern 14-P1 and the second security pattern 14-P2. The line pitch of the first security pattern 14-P1 follows the line width, which may be between 40 μm and 400 μm, and the facial image is formed by changing the line width.

[0062] A laser beam is irradiated from the overlay 16 side of the obtained information recording medium 12, and the laser print layer 20 is carbonized by the laser beam from above the first security pattern 14-P1 in the second image 14 area (shown as L in FIG. 4), thereby forming the second security pattern 14-P2. At this time, because the first security pattern 14-P1 is formed from infrared-transmitting ink, there is little energy loss of the laser beam, making reliable laser engraving possible.

[0063] The formed second security pattern 14-P2 becomes another moiré image. The second security pattern 14-P2 may or may not be linear. The pattern pitch of the second security pattern 14-P2 only needs to be narrower than the distance between the first security pattern 14-P1 and the second security pattern 14-P2. By forming the second security pattern 14-P2 at a position offset from the first security pattern 14-P1, the image changes when the information recording medium is tilted. Furthermore, the line pitch of the security pattern 14-P2 follows the line pitch of the first security pattern 14-P1, and the line width of the security pattern 14-P2 only needs to be 20 μm or more and less than the line width of the first security pattern 14-P1.

[0064] (Authenticity determination) Figure 5 is a cross-sectional view of an information recording medium that schematically shows the difference in image depending on the observation position of the second image, and shows the information recording medium 12 viewed from a viewing angle A (front) 22 and a viewing angle B (diagonal) 23 as viewed from the side.

[0065] Figure 6 is a front view of information recording body image 24 when authenticated at viewing angle A (front) obtained by observing at viewing angle A (front) 22, and an oblique view of information recording body image 26 when authenticated at viewing angle B (diagonal) 23 obtained by observing at viewing angle B (diagonal) 23.

[0066] When the information recording body image 24 is viewed from the front at a viewing angle A22, the second image 14 is observed as a monochrome facial image 25, whereas when the information recording body image 26 is viewed obliquely at an oblique viewing angle B23, a security effect (moire) occurs in the second image 14, and an image 27 is observed in which a latent image of personal information, such as a date of birth, that was not observed at the viewing angle A22 is made visible.

[0067] In this way, the security latent images of the first security pattern 14-P1 and the second security pattern 14-P2 formed by the security panel S, which cannot be observed individually, can be made into visible images 27 by changing the observation angle of the information recording medium 12, whereby moire patterns appear.

[0068] An example of this embodiment will be described below. (Preparation of thermal transfer medium) On one side of a 4.5 μm polyethylene terephthalate (PET) substrate, which served as a support, a hue panel containing black (K), cyan (C), magenta (M), and yellow (Y) pigments, a security panel (S), and an adhesive panel (P) were sequentially formed using a gravure coater with a mixed resin made by mixing various pigments into a polyester resin.The thickness of the color panel was 1.0 μm, the thickness of security panels 1 to 3 was 1.2 μm, and the thickness of the primer panel (P) was 1.2 μm, forming a thermal transfer medium.

[0069] The composition of each ink is as follows: [Cyan ink composition] Cyan pigment 5 parts by weight Byron 500 (Toyobo Co., Ltd.) 15 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight [Magenta ink composition] Magenta pigment 5 parts by weight Byron 500 (Toyobo Co., Ltd.) 15 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight [Yellow ink composition] Yellow pigment 5 parts by weight Byron 500 (Toyobo Co., Ltd.) 15 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight [Black ink composition] Carbon black pigment 5 parts by weight Byron 500 (Toyobo Co., Ltd.) 15 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight [Security ink composition] Infrared transparent ink Cyan pigment 3 parts by weight Magenta pigment 3 parts by weight Yellow pigment 4 parts by weight Byron 500 (Toyobo Co., Ltd.) 10 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight [Primer composition] Byron 500 (Toyobo Co., Ltd.) 20 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight

[0070] (Preparation of intermediate transfer foil) An epoxy resin was formed as an overlay layer to a thickness of 0.8 μm on one side of a 12 μm polyethylene terephthalate (PET) substrate using a gravure coater to obtain an intermediate transfer foil 6. The ink composition of the overlay layer is as follows: [Ink composition for overlay layer] jER1003 (Mitsubishi Chemical Corporation) 20 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight

[0071] (Production of information recording medium) The information recording medium was produced by the method shown in (Method for producing information recording medium) described above with reference to FIG.

[0072] The first image 13 was formed using the colorant panels cyan (C), magenta (M), and yellow (Y), and the character string 15 was formed using black (K). Furthermore, the second image 14 was formed as a first security pattern 14-P1 using a security panel (S) and printed on the surface of the card. The first security pattern 14-P1 formed by the security panel (S) is one of the moiré images. The first security pattern 14-P1 was formed as a line (straight line) image with a line width of 40 μm to 120 μm.

[0073] The second image 14 was formed as an image with a line width of 40 μm, which was observed by combining the first security pattern 14-P1 printed on the same layer as the above-mentioned images using the security panel (S), and the second security pattern 14-P2 printed by selectively irradiating the laser coloring layer with laser light using a YVO4 laser (1064 nm) through the first security pattern 14-P1. Each was a line pattern, and it was confirmed that the latent image of the character strings placed within the facial image was visualized by the contrast of the moire that occurred depending on the observation angle.

[0074] Based on the above, it was possible to produce a thermal transfer medium with a new security panel using the same processing steps as for ordinary thermal transfer medium, and by combining this with laser engraving, it was possible to produce an information recording medium that can be used for personal authentication with image changes due to moire.

[0075] In particular, since the formation of an image indicating authenticity in authentication is not dependent on the ink or optical properties of a single layer, but is only manifested by a combination of information formed on multiple layers, an information recording medium with extremely high resistance to alteration and counterfeiting has been produced. [Explanation of symbols]

[0076] 1. Thermal transfer medium 2...Support K···Black Panel C···Cyan Panel M···Magenta Panel Y Yellow Panel S···Security Panel (Infrared Transmitting Ink Panel) P···Primer Panel 3. Thermal transfer media unwinding section 4. Thermal transfer medium take-up section 5. Thermal head 6. Intermediate transfer foil 7. Intermediate transfer foil unwinding section 8. Intermediate transfer foil winding section 9. Heat roll 10 Platen roller 11. Information recording medium substrate 12. Information recording medium 13···First image 14···Second image 14-P1: First security symbol in the second image 14-P2: Second security symbol in the second image 15... String A-A' cross section L... Laser coloring (carbonized area) h: Distance between Pattern 1 and Pattern 2 16. Overlay 17. Peeling layer 18. Receiving layer 19. Core sheet 20...Laser printable sheet 21 Protective laminate sheet 22. Viewing angle A (front) 23. Viewing angle B (diagonal) 24...Image of information recording body when authenticated at viewing angle A 25···Image A 26...Image of information recording body when authenticated at viewing angle B 27···Image B 101 Primary transfer unit 102 Secondary transfer unit

Claims

1. An information recording medium comprising a first protective layer, a laser coloring layer, a core layer, a second protective layer, and an overlay layer, each of which is made of a plastic sheet, laminated in this order, wherein the overlay layer contains at least a first security pattern formed on demand with an infrared-transmitting ink, and an image obtained by superimposing the first security pattern on a second security pattern formed on demand by laser engraving on the laser coloring layer, enables the display of different security pattern information depending on the observation angle.

2. 2. The information recording medium according to claim 1, wherein the security image information, which varies depending on the observation angle, is visualized by a moire pattern.

3. 3. The information recording medium according to claim 1, wherein the overlay layer is formed by adhering an intermediate transfer foil containing a pattern formed by a thermal transfer method to the second protective layer.

Images