JP7491054B2 - Thermal transfer medium and information recording medium - Google Patents

Description

The present invention relates to a thermal transfer medium for producing information recording media for personal authentication, such as passports and ID cards, and to information recording media using the same.

Conventionally, printed materials on which characters and images are printed in various ways, particularly personal authentication media such as passports and ID cards, as well as information recording media requiring security such as credit cards and bankbooks, have been provided with images with special visual effects in order to provide security to prevent counterfeiting and tampering, and to impart authenticity and design to show that the item is genuine, in addition to the usual facial photographs and images of text information.

In the case of the indirect transfer recording method using a thermal transfer medium and intermediate transfer foil, the effect of an optically variable element, such as a hologram, placed in the intermediate layer of the intermediate transfer foil provides anti-counterfeiting properties. The three-dimensional images and color changes expressed by holograms and the like have the advantage of being highly decorative and difficult to counterfeit, but there is also the issue that when something that appears to have a similar effect is used instead, it is difficult to distinguish between the two when trying to visually determine whether they are genuine or not, unless you are an expert in authenticity determination.

In addition, colors that cannot be reproduced with the toner of a color digital copier are printed to make it difficult to reproduce with a color copy machine. For example, methods are known in which special colors such as green, purple, orange, gold, and silver are printed to reduce the reproducibility of the colors in the copy, and further, a light source material with interference colors is printed to make it even more difficult to reproduce the copy with a color digital copier.

Alternatively, authenticity can be determined by using fluorescent ink that is invisible under normal circumstances (it emits light in the visible light range when exposed to ultraviolet light) and making it color when a specific wavelength of light is irradiated onto a part that would normally be invisible to the naked eye, or by using special ink and having it authenticated by a compatible verification device.

For example, Patent Document 1 discloses an ink ribbon with the following characteristics as a special ink ribbon for use in a thermal indirect transfer printer. That is, in an ink ribbon having a primer panel, a security layer is pattern-printed between the two-layer primer layer. When printed, a recording medium is obtained in which security characters appear to be printed in pearl on the entire surface of the card on the base material side (lower layer when viewed from the front side) beyond the color layers (YMCK).

The above methods are suitable for forming a common security pattern, but they cannot form individual security information on demand. Therefore, while they are good for identifying whether the information recording medium, such as a card, is genuine, it is impractical to create a print version for each card in order to be able to determine whether the information displayed on the issued card is genuine. In addition, some methods require users to install special verification equipment, which is a heavy burden.

Information counterfeiting and tampering are becoming more and more sophisticated, and new security features are constantly being required. In particular, facial images, which contain important personal information, are often counterfeited or altered by peeling off the transfer film from the top or bottom of the transfer foil on which the facial photo is printed, and new counterfeit prevention measures are required.

JP 2018-176663 A

The present invention was made in consideration of these problems, and aims to provide a thermal transfer medium suitable for an indirect transfer recording method that allows for determination of whether the information printed on each information recording medium is genuine, is difficult to tamper with without leaving any trace of fraud, and is unlikely to be an incentive for counterfeiting or tampering, and an information recording medium using the same.

In order to solve the above problem, one aspect of the present invention is
This is a thermal transfer medium having ink panels of multiple colors of thermal transfer inks applied in a surface-sequential manner on a support, the ink panels having at least ink panels of a first security layer, black, cyan, magenta, yellow, a second security layer, and an adhesive layer, which are applied in that order, and the first security layer and the second security layer are layers that contain photoluminescent inks and do not contain a dye receiving layer .

In the above-mentioned thermal transfer medium, the photoluminescent ink contained in the first security layer and the photoluminescent ink contained in the second security layer may have different hues.

In the above-mentioned thermal transfer medium, the photoluminescent ink contained in the first security layer and the photoluminescent ink contained in the second security layer may have the same hue.

In the above-mentioned thermal transfer medium, at least one of the first security layer and the second security layer may be a layer containing a fluorescent agent.

Another aspect of the present invention is
This information recording medium is produced using the above-mentioned thermal transfer medium, and is characterized in that a pattern layer is formed on a substrate in which a first security pattern layer is formed by transferring the thermal transfer ink of the first security layer, a visual image layer formed from the thermal transfer inks transferred from black, cyan, magenta, and yellow ink panels, and a second security pattern layer is formed by transferring the thermal transfer ink of the second security layer are sequentially laminated.

The thermal transfer medium of the present invention allows a pattern using photoluminescent ink to be formed so as to sandwich a color layer containing personal information from above and below, making it possible to prevent attacks from both the front and back that would attempt to tamper with the information, resulting in a personal authentication medium that is difficult to tamper with and has high security.

1 is a schematic diagram illustrating one embodiment of a heat-sensitive transfer medium of the present invention. FIG. 1 is a schematic diagram showing an example of a printer for forming an information recording medium of the present invention. 1 is a schematic diagram showing one embodiment of the information recording medium of the present invention. FIG. 1 is a cross-sectional view of one embodiment of an information recording medium of the present invention taken along the line X-X'. 5A to 5C are schematic diagrams showing an example of changes in a latent image when an information recording medium according to an embodiment of the present invention is tilted and irradiated with ultraviolet light. FIG. 2 is an enlarged view of a portion of a color image.

The following describes in detail the embodiments of the present invention with reference to the drawings. Note that the present invention is not limited to the embodiments described below. In addition, the embodiments described below have technically preferable limitations for implementing the invention, but these limitations are not essential requirements for the present invention.

Figure 1 is a schematic diagram of the appearance of one embodiment of the thermal transfer medium of the present invention. The thermal transfer medium 1 is formed by applying a plurality of thermal transfer ink panels in the longitudinal direction on a support 2 in a surface-sequential manner. The thermal transfer ink panel is formed from a first security ink panel PS1 containing a glittering ink A, four color ink panels of black K, cyan C, magenta M, and yellow Y, a second security ink panel PS2 containing a glittering ink B, and an adhesive layer panel 3. That is, the security ink panels PS1 and PS2 are arranged on both sides of the ink panels of K, C, M, and Y that form the color material layers of a normal visual image. The size of each panel can be appropriately set according to the specifications of the recording size of the information recording medium to be finally recorded. In addition, a sensor mark M may be provided as necessary. In addition, a backcoat layer (not shown), such as a heat-resistant layer or a slipping layer, may be provided on the side opposite to each ink panel of the support 2.

With a thermal transfer medium of this configuration, it is easy to first transfer an arbitrary pattern from the first security ink panel PS1 to the intermediate transfer medium using an indirect transfer recording device, form a color image on top of it using four color inks: black K, cyan C, magenta M, and yellow Y, and then transfer an arbitrary pattern on top of it from the second security ink panel PS2. In other words, it is easy to make the color image sandwiched between security ink layers from both the upper and lower sides. Furthermore, by transferring an adhesive layer, it is possible to ensure that the transfer to the transfer target can be performed reliably.

There are no particular restrictions on the photoluminescent ink A and photoluminescent ink B, and they can be appropriately selected from existing photoluminescent pigments dispersed in binder resins, etc. Photoluminescent ink A and photoluminescent ink B may be of different types or the same type. The photoluminescent pigments used may be of different types or the same type. Selection can be made according to the application, and using the same color can create the illusion that there is only one security hole. Using different colors can also create a more complex appearance, such as changing color depending on the viewing angle.

The luster pigment is, for example, a pigment with a synthetic mica core, coated with titanium oxide or silicon oxide, which exhibits a color when the viewing angle is changed with respect to the object. For example, if titanium oxide of a specified thickness is provided, it will exhibit a structural color of green when tilted. The luster pigment is not limited to the above example, and titanium oxide of a thickness that exhibits other colors such as red or blue when tilted may be used depending on the application. It is also possible to use a pigment that is further coated with iron oxide on the outside to change from reddish brown to a specific color. The structural color effect is produced by the thickness of the titanium oxide or silicon oxide coating and the refractive index of the coating material, so that when tilted, it exhibits a color according to the wavelength of the reflected light. In other words, the amount of coating can be controlled and designed to provide an optical path length according to the wavelength of the required color.

As mentioned above, the pattern formed with ink containing photoluminescent pigments is invisible under normal viewing conditions, but can be made visible when tilted at a certain angle, and can be used as a latent image, which has the effect of suppressing counterfeiting and tampering, and can also be used as a security feature as it makes tampering easier to detect. In addition, because it is an ink ribbon, individual patterns of any shape can be easily formed with a thermal head, further increasing security.

In addition, at least one of the security ink panels PS1 and PS2 can contain a fluorescent agent. For example, the security ink panel PS1 can contain a fluorescent agent that is excited with energy and emits red light when irradiated with ultraviolet light, and the security ink panel PS2 can contain a fluorescent agent that is excited with energy and emits blue light when irradiated with ultraviolet light. However, this is not limited to this, and any luminescent material that is invisible under visible light, i.e., white or transparent, and that emits light in the visible light range when irradiated with special light such as ultraviolet light, can be used.

The fluorescent agent used in security ink panel PS1 and security ink panel PS2 can be any luminescent material that is invisible under visible light, i.e., white or transparent, and emits light in the visible light range when irradiated with special light such as ultraviolet light. The fluorescent agents used in security ink panel PS1 and security ink panel PS2 can be the same or different. If they are different, the emitted light of different hues will appear to overlap after transfer, forming a more complex emission pattern and achieving a gradation-like effect. By including a fluorescent agent, the special color of light is only visible when irradiated with ultraviolet light, making it easier to detect counterfeiting or tampering, and by using it in combination with a photoluminescent pigment, security is further enhanced.

The binder resin used in each ink panel can be any substantially transparent thermoplastic resin, such as acrylic resin, styrene resin, polyester resin, epoxy resin, vinyl resin, rosin resin, polyamide resin, etc., but is not limited to these. Each thermoplastic resin can be used alone or as a mixture, or even as a composite such as a copolymer.

Examples of thermoplastic resins used in the adhesive layer panel 3 include, but are not limited to, acrylic resins, polyester resins, polyurethane resins, polyamide resins, vinyl resins such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymers, chlorinated polyolefins, ethylene-acrylic copolymers, epoxy resins, and rosin resins. These thermoplastic resins can be used alone or as a mixture or composite of two or more. Depending on the situation, waxes and the like may be added in addition to inorganic fillers and organic fillers.

Figure 2 is a schematic block diagram of an example of a contact transfer recording device that creates an information recording medium using the thermal transfer medium of the present invention. The information recording medium of the present invention can be created by a thermal transfer printer using the thermal transfer medium as described above. Figure 2 shows an example of a thermal transfer printer that is an indirect transfer type printer. In the indirect transfer recording device 100, the thermal transfer medium 1 is unwound from the unwinding roll 4, passes between the thermal head 6 and the platen roller 11 of the primary transfer section 101 that performs thermal transfer printing on the intermediate transfer film 7, and is wound up on the winding roll 5. In addition, the intermediate transfer film 7, which has at least an overlay layer releasably provided on the substrate, is unwound from the unwinding roll 8, passes between the thermal head 6 and the platen roller 11 of the primary transfer section 101, passes between the heat roller 10 and the platen roller 11 in the secondary transfer section 102 that performs thermal pressure transfer to the transferee 12, and is wound up on the winding roll 9. Here, the overlay layer is a layer that also serves as an image receiving layer for the thermal transfer ink of the thermal transfer medium.

In the primary transfer section 101, a predetermined pattern including photoluminescent ink A is transferred from the first security ink panel PS1 onto the overlay layer, which also serves as the image receiving layer of the intermediate transfer film 7, from the thermal transfer medium 1. Then, a color image, a pattern including letters, etc. are transferred from the four ink panels of black K, cyan C, magenta M, and yellow Y, superimposed on the predetermined pattern including photoluminescent ink A, and then a predetermined pattern including photoluminescent ink B is superimposed and transferred from the second security ink panel PS2. That is, the color image, the pattern including letters, etc. is sandwiched between the predetermined pattern including photoluminescent ink A and the predetermined pattern including photoluminescent ink B. However, a part of the pattern including the color image, the pattern including letters, etc. may be transferred to a part that is not sandwiched between the predetermined pattern including photoluminescent ink A and the predetermined pattern including photoluminescent ink B. It goes without saying that the color image pattern may not include some colors, for example black. Next, the adhesive layer panel 3 is further superimposed and transferred over the entire area to be transferred to the transferee 12, such as a card.

The intermediate transfer film 7 on which each pattern has been formed is transported to the secondary transfer section 102, where it is thermally pressed onto the transferee 12 by the heat roller 10, so that each pattern formed in the primary transfer section 101 is transferred to the transferee 12 together with the overlay layer. By appropriately controlling the thermal head 6, any pattern, whether it be a color image or character pattern, or a pattern of photoluminescent ink A or photoluminescent ink B, can be created, and any individual information can be formed on the intermediate transfer film 7 and then on the transferee 12.

Figure 3 is a plan view of one embodiment of the information recording medium of the present invention on which each image pattern and photoluminescent ink pattern are formed as described above. The information recording medium 13 is typically in the form of a card such as an ID card, but may be in the form of a sheet or booklet, and is not particularly limited as long as it has a flat recording surface. The information recording medium 13 has a color image 14 in which a face photo image pattern formed by transferring from three ink panels of cyan C, magenta M, and yellow Y is sandwiched between a pattern of a first security layer S1 containing photoluminescent ink A transferred from a first security ink panel PS1 and a pattern of a second security layer S2 containing photoluminescent ink B transferred from a second security ink panel PS2, and characters 15 formed by transferring from a black K ink panel.

Figure 4 shows an example of a cross section of an information recording medium on which each image pattern is formed, cut along line segment X-X'. The information recording medium 13 has a transfer-receiving material 12 as a base material, on whose surface is a color image 14, in which a pattern of a face photo image (indicated by CMY) in cyan C, magenta M, and yellow Y inks is sandwiched between a predetermined pattern in an overlay layer 16 made of a first security layer S1 containing photoluminescent ink A and a predetermined pattern in a second security layer S2 containing photoluminescent ink B, characters 15 formed by transfer from a black K ink panel, and an adhesive layer panel 3, which are transferred in a superimposed manner.

This complex layer structure is not easy to reproduce, and is effective in preventing counterfeiting, forgery, and alteration. It is also effective in preventing tampering with facial photographs, which are particularly important personal information; if an attempt is made to tamper from the front side (top of the figure), the pattern of the first security layer S1 will be damaged, and if an attempt is made to tamper from the back side (bottom of the figure), the pattern of the second security layer S2 will be damaged. Therefore, no matter which side the tampering is attempted from, traces will remain, making it easy to discover that it has been attempted, and it is also effective in preventing tampering and alteration in advance. Each security layer can also be provided in the part of the characters 15 if necessary, so that the part of the characters 15 can also be protected in the same way.

Furthermore, by incorporating a fluorescent agent into the first security layer S1 or the second security layer S2, or both, more complex color and light emission patterns can be obtained by combining them. By changing the type of fluorescent agent used and further shifting the printing areas of each security layer, it is possible to create partial overlapping of the security layers and create a three-color area when exposed to ultraviolet light.

The shape, size and location of the pattern of the first security layer S1 and the pattern of the second security layer S2 can be set arbitrarily, and they may be arranged to cover only a part of the color image, or they may be arranged to differ in size or in different locations. In addition, various personal information such as ID numbers and names can be included in each pattern, and security can be further increased by encrypting the personal information before including it. In the example of Figure 3, the pattern of the second security layer S2 is a larger pattern. The effect of this case will be explained in more detail using Figure 6.

Figure 6 is an enlarged view of a portion of the color image 14. In this portion, the pattern of the first security layer S1, the facial photograph image in cyan C, magenta M, and yellow Y inks (indicated as CMY), and the pattern of the second security layer S2 overlap when viewed from the viewing direction, and are different sizes. Therefore, when viewed from the viewing direction, in area A, the pattern of the first security layer S1 overlaps the facial photograph image CMY, in area B, the pattern of the first security layer S1 and the pattern of the second security layer S2 overlap, and in area C, only the pattern of the second security layer S2 is visible. Therefore, the appearance of the portion of the color image 14 changes when the angle at which this information recording medium is viewed is changed or when ultraviolet light is applied.

The effect of the glittering pigment when the information recording medium 13 is tilted at a specified angle is that in area A, the facial photograph image and the structural color of the first security layer S1 appear to overlap in the area with the facial photograph image, and in areas of area A without the facial photograph image and area B, the structural color of the first security layer S1 and the structural color of the second security layer S2 appear either alone or overlapping depending on the angle of tilt. In area C, the structural color of the second security layer S2 becomes visible.

The top diagram in Figure 5 shows the information recording medium 13 shown in Figure 4, viewed almost from the front. At this time, the photo luminescent ink patterns of the first security layer S1 and the second security layer S2 are not visible, and the patterns are in the form of latent images, and the facial photograph image is visible in the normal state.

When this information recording medium 13 is viewed in a tilted state as shown in the middle diagram of Figure 5, in the area where the photoluminescent ink pattern is provided, the structural color of the first security layer S1 or the structural color of the second security layer S2 appears to be manifested depending on the angle of tilt as described above. Therefore, by switching between viewing from the front and viewing at an angle, the patterns of each color become visible or invisible, which can be used as a security function to determine authenticity. As described above, the photoluminescent ink pattern in this case can be a pattern of any individual information, such as a name or ID number.

The lower diagram in Figure 5 shows an example in which the first security layer S1 and the second security layer S2 contain a fluorescent agent. When ultraviolet light is applied from the ultraviolet light source 17, the area containing the fluorescent agent emits fluorescence. For example, if the first security layer S1 contains a fluorescent agent that emits red light and the second security layer S2 contains a fluorescent agent that emits blue light, when ultraviolet light is applied, the area only containing the first security layer S1 emits red light (area A), the area where the first security layer S1 and the second security layer S2 overlap emits magenta light due to a mixture of red and blue light (area B), and the area only containing the second security layer S2 emits blue light (area C), forming a three-color color change area overall.

The presence of the latent images created by the first security layer S1 and the second security layer S2 can be confirmed by changing the angle of the information recording medium, which causes a color change, but the effect of the fluorescent agent is not noticed until it is exposed to ultraviolet light. Generally, a security function is considered more secure if it is not obvious that the function exists, so this has the effect of further enhancing security.

As described above, the present invention has the following advantages.
- By using a thermal transfer medium (ink ribbon) with photoluminescent ink having structural color, personal information (characters, images, symbols, figures, etc.) can be produced on demand, and personal information accompanied by optical changes can be confirmed simply by tilting the information recording body. Furthermore, since any tampering leaves a trace, it is possible to easily and quickly determine whether the information has been forged or altered. Furthermore, by using a thermal transfer medium (ink ribbon) with photoluminescent ink containing a fluorescent agent, the difficulty of ribbon production increases. Personal information can be confirmed not only under visible light, but also under ultraviolet light, providing two levels of security.
- By using photoluminescent pigments in the security layer, it becomes difficult to reproduce using color digital copiers or inkjet printers.
By using the same color lustrous pigment in the first security layer S1 and the second security layer S2, the security pattern can be recognized as a single pattern when the information recording medium is tilted and visually inspected under visible light.
By selecting a material for the fluorescent agent used in the first security layer S1 and the second security layer S2 that is colorless under visible light and emits different colors under ultraviolet light, at first glance it appears as a single security pattern under visible light (because it is the same color, it appears as if there is only one security layer), but when exposed to ultraviolet light, it emits multiple colors, providing a two-stage security function.
By intentionally printing the first security layer S1 and the second security layer S2 offset from one another, when viewed from above, a color change of one color of photoluminescent pigment is observed under visible light, but a color change area of three colors is formed under ultraviolet light, allowing for more complex security measures to be implemented.

(Preparation of Thermal Transfer Medium)
On one side of a 12 μm thick polyethylene terephthalate (PET) substrate serving as a support, a security ink panel PS1 prepared using security ink 1 containing fluorescent agent A and photoluminescent pigment A, a color ink panel containing each of the pigments black K, cyan C, magenta M, and yellow Y, a security ink panel PS2 prepared using security ink 2 containing fluorescent agent B and photoluminescent pigment A, and an adhesive layer panel were successively formed using a gravure coater, with the color ink panel being 1.0 μm thick, the security ink panels PS1 and PS2 being 1.2 μm thick, and the adhesive panel being 1.2 μm thick to form a thermal transfer medium.
The luster pigment A has a core of synthetic mica (synthetic glass) coated with titanium oxide (TiO ₂ ), and appears green when tilted.
Fluorescent agent A is a pigment that emits red light when irradiated with ultraviolet light, and fluorescent agent B is a pigment that emits blue light when irradiated with ultraviolet light.

[Cyan Ink Composition]
Cyan pigment: 5 parts by weight Vylon 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 Vylon 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 Vylon 500 (Toyobo Co., Ltd.) 15 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight [Composition of black ink]
Carbon black pigment: 5 parts by weight Vylon 500 (Toyobo Co., Ltd.) 15 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight

[Composition of Security Ink 1]
Luminescent pigment A 5 parts by weight Fluorescent agent A 3 parts by weight Vylon 500 (Toyobo Co., Ltd.) 15 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight [Composition of security ink 2]
Luminescent pigment A 5 parts by weight Fluorescent agent B 3 parts by weight Vylon 500 (Toyobo Co., Ltd.) 15 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight

(Preparation of intermediate transfer medium)
An epoxy resin was applied as an overlay layer to a thickness of 0.8 μm on one side of a 12 μm polyethylene terephthalate (PET) substrate by a gravure coater, to obtain an intermediate transfer medium 1.
[Ink Composition of Overlay Layer]
jER1003 (Mitsubishi Chemical Corporation) 20 parts by weight MEK (Toyo Ink Mfg. Co., Ltd.) 80 parts by weight

(Printing test)
The intermediate transfer medium and the thermal transfer medium were mounted in a card printer CP500 (manufactured by Toppan Printing Co., Ltd.), and an information recording medium was produced by printing an image in the same layout as in the example shown in FIG. 3 onto a PVC card as the transfer medium.
The results were as follows:
- By using an image pattern thermal transfer medium, any image, character, figure, etc. can be formed on demand.
By tilting the authentication card under visible light, the photoluminescent pigments in security ink 1 and security ink 2 were made the same color, and a color change from colorless to green was observed as a single image.
When authentication was performed under ultraviolet light, the area where only security ink 1 was present glowed red (area A), the area where security ink 1 and security ink 2 overlapped glowed magenta due to a mixture of red and blue light (area B), and the area where only security ink 2 was present glowed blue (area C), and color change areas were confirmed throughout.

The presence of a latent image made of photoluminescent pigment could be confirmed by changing the angle of the information recording medium, which caused a color change, but the presence of a latent image made of fluorescent agent could not be discovered until the information recording medium was irradiated with ultraviolet light.

(Tampering test)
Attack from above: An attempt was made to scratch the part of the overlay layer that corresponds to the color image 14 and falsify the image. When the face photo image was tampered with, the destruction of the first security layer S1 was confirmed, and traces were left behind.
- Attack from below: Using a special solvent, the entire layer transferred by the printer was peeled off from the information recording medium, and the facial photo image was altered from the adhesive layer side. When the facial photo image was altered, the destruction of the second security layer S2 was confirmed, and traces were left behind. In this case, the pre-print on the card, which is the base material of the information recording medium, remained unchanged, and it was only from the traces of counterfeiting on the second security layer S2 that it was discovered that it had been tampered with, confirming that security had been strengthened.

If tampering or alteration is attempted from various parts, traces can be easily found, and it has been confirmed that sandwiching an image containing personal information between the first security layer S1 and the second security layer S2 is effective. In addition, because each security layer has a different effect, a more complex anti-counterfeiting effect can be achieved.

1...Thermal transfer medium 2...Support body PS1...First security ink panel PS2...Second security ink panel K...Black C...Cyan M...Magenta Y...Yellow 3...Adhesive layer panel 4...Unwinding roll 5...Take-up roll 6...Thermal head 7...Intermediate transfer foil 8...Unwinding roll 9...Take-up roll 10...Heat roller 11...Platen roller 12...Transferee 13...Information recording body 14...Color image CMY...Facial photo image S1...First security layer S2...Second security layer 15...Character 16...Overlay layer 17...Ultraviolet light source

Claims (5)

A thermal transfer medium having ink panels of multiple colors of thermal transfer inks applied in a surface-sequential manner on a support, the ink panels having at least the following ink panels applied in that order: a first security layer, black, cyan, magenta, yellow, a second security layer, and an adhesive layer , the first security layer and the second security layer being layers that contain photoluminescent inks and do not contain a dye-receiving layer . The thermal transfer medium according to claim 1, characterized in that the photoluminescent ink contained in the first security layer and the photoluminescent ink contained in the second security layer have different hues. The thermal transfer medium according to claim 1, characterized in that the photoluminescent ink contained in the first security layer and the photoluminescent ink contained in the second security layer have the same hue. The thermal transfer medium according to any one of claims 1 to 3, characterized in that at least one of the first security layer and the second security layer is a layer containing a fluorescent agent. An information recording medium produced using the thermal transfer medium according to any one of claims 1 to 4, characterized in that a pattern layer is formed on a substrate, in which a first security pattern layer formed by transferring the thermal transfer ink of the first security layer, a visual image layer formed by the thermal transfer ink transferred from black, cyan, magenta, and yellow ink panels, and a second security pattern layer formed by transferring the thermal transfer ink of the second security layer are sequentially laminated.

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