JP7516948B2 - Anti-counterfeiting media - Google Patents

Description

Regarding anti-counterfeiting media.

Currently, there is a growing trend around the world to use ID cards made of polycarbonate material. This is effective in preventing physical tampering of ID information from outside the card by recording the ID information inside the card using laser engraving (laser drawing).

However, the main security technologies for the card itself other than the ID information are still printing with special inks such as OVI and inserted holograms, and these technologies are unreliable because authenticity can only be determined by visual inspection, and many counterfeit products are in circulation. For this reason, there is a demand for simple verification methods that do not rely on visual inspection, such as image recognition judgment of images captured by a smartphone.

The mainstream security technology for ID information (variable information) such as names and photographs is lenticular lenses (MLI/CLI). However, there have been reports of these being forged by scraping away information from the back, so countermeasures are needed.

In response to these issues, a technology has been proposed that uses retroreflective technology to ensure the authenticity of the card itself and increase security (see Patent Document 1 below). This provides a medium that is difficult to replicate by arranging retroreflective glass beads containing inorganic phosphors and retroreflective glass beads in a specific pattern on a substrate by printing.

Furthermore, a measure has been proposed to make counterfeiting more difficult by providing a concealing layer on the retroreflective material (see Patent Document 2 below). This is a countermeasure to prevent counterfeiting by making it difficult to recognize the presence or absence of the retroreflective layer or to distinguish the pattern on the retroreflective layer using a black concealing layer.

From the perspective of preventing counterfeiting, a technology has also been proposed in which a latent image is formed on a retroreflective layer (Patent Document 3 below). This is a technology in which a multilayer birefringent pattern containing optical isomers arranged in at least one pattern on the retroreflective layer is provided, so that the latent image is only visible under specific optical conditions.

JP 2002-189433 A JP 2019-048397 A JP 2013-073021 A

However, in the technology of Patent Document 1, the particle diameter of the glass beads used in the retroreflective layer is large, and screen printing is used to apply the pattern, which means that on-demand printing for recording variable information for ID applications is not possible.

The technology in Patent Documents 2 and 3 above allows on-demand printing onto the retroreflective layer using an inkjet printer, but has the disadvantage that the variable information is present on the outermost layer and can easily be altered or forged by, for example, physically scraping it off.

The present invention has been made to address the above-mentioned problems, and aims to provide a highly secure anti-counterfeit medium that incorporates retroreflective technology into a medium whose main component is polycarbonate resin, and that can record variable information such as a name, facial photograph, and QR code (registered trademark) by laser engraving inside a layer whose main component is polycarbonate resin as a latent image, i.e., an image that can only be observed under specific optical conditions, and that makes it difficult to falsify this variable information by physical means such as scraping it off from the outside.

As a means for solving the above problems, the invention described in claim 1 provides a laser-colored optical disc comprising at least a core layer mainly made of polycarbonate resin, a laser coloring layer mainly made of polycarbonate resin, and an overlay layer mainly made of polycarbonate resin, laminated in this order;
A retroreflective layer is provided in a partial area between the core layer and the laser coloring layer,
The counterfeit prevention medium is characterized in that a concealment layer is provided in a partial area between the laser coloring layer and the overlay layer, the concealment layer blocking visible light weaker than flash light and transmitting infrared laser light.

The invention described in claim 2 is the counterfeit prevention medium described in claim 1, characterized in that a pattern layer is sandwiched between the concealing layer and the laser coloring layer.

The invention described in claim 3 is the counterfeit prevention medium described in claim 1 or 2, characterized in that the concealing layer is either mixed black ink, a black material that absorbs specific wavelengths, or carbon black, or is made by combining these materials in a predetermined pattern.

The invention described in claim 4 is the counterfeit prevention medium described in any one of claims 1 to 3, characterized in that variable information is recorded as a latent image in the laser coloring layer by laser light drawing.

According to the present invention, variable information can be easily recorded as a latent image by laser engraving from above the concealing layer.

In addition, the variable information recorded is written on the laser coloring layer, which is the middle layer of the medium, making it difficult to physically scrape off or tamper with the medium from either the front or back.

In particular, the back side, which is less noticeable and therefore more likely to be scratched, is covered with a retroreflective layer, making it more difficult to tamper with, thus maintaining a high level of security.

In addition, according to the present invention, the latent image as a security element is formed by simply combining a concealing layer, a laser coloring layer, and a retroreflective layer. This means that the latent image can be observed easily and regardless of the amount of external light, without the need for special optical devices such as UV lights and polarizing filters that have been used in the past, for example, with just a flashlight and a digital camera equipped on a smartphone (Figure 2).

In addition, since the light reflected from the retroreflective layer only returns in the direction of the incident light for observation, the latent image can only be observed at the verification shooting position, and cannot be observed if the viewing position is different. This prevents a third party from secretly viewing the image (Figure 3).

In addition, according to one aspect of the present invention, by selecting the method for forming the concealing layer, it is possible to impart different latent images to different observation wavelengths, thereby ensuring a higher level of security.

In addition, when implementing the present invention, all that is required is to provide a retroreflective layer on one side of a laser coloring layer whose main component is polycarbonate resin, and a concealing layer on the other side. This means that manufacturing equipment already in operation for the manufacture of ID cards and passport data pages that use polycarbonate substrates can be used as is, making the invention easy to implement.

Furthermore, the laser drawing machine used for printing can be the same as the one generally used, so there is no need for the user to make any special changes when using the counterfeit prevention medium of this configuration, ensuring versatility.

FIG. 4 is a cross-sectional view of the counterfeit prevention medium before laser engraving in the first embodiment. FIG. 4 is a schematic cross-sectional view of a counterfeit prevention medium showing a latent image observed from the front in the first embodiment. FIG. 4 is a schematic cross-sectional view of a counterfeit prevention medium showing a latent image observed from an oblique angle in the first embodiment. 1A is a cross-sectional view of a counterfeit prevention medium after laser engraving in embodiment 1. FIG. 1B is a plan view of each observation condition before and after laser engraving in example 1. 1A is a cross-sectional view of a counterfeit prevention medium after laser engraving in embodiment 2. FIG. 1B is a plan view of each observation condition before and after laser engraving in example 2. 13A is a cross-sectional view of a counterfeit prevention medium after laser engraving in embodiment 3. FIG. 13B is a plan view of each observation condition before and after laser engraving in example 3.

Each embodiment will be described below using Figures 1, 4A, 5A, and 6A.

<Embodiment 1>
1 is a schematic diagram showing the cross-sectional structure of the counterfeit prevention medium 1 described in claim 1. A retroreflective printed layer 21 is formed between a core layer 11 mainly made of polycarbonate and a laser coloring layer 12 made of a laser coloring substrate mainly made of polycarbonate, and a concealing layer 22 made of mixed black ink is formed between the laser coloring layer 12 and an overlay layer 13 mainly made of polycarbonate.

Figure 4A is a schematic diagram showing the cross-sectional structure of the counterfeit prevention medium 1 shown in Figure 1 after laser engraving. It shows that the part 12a that is exposed to the laser light has turned black.

In this embodiment, the base material of the anti-counterfeiting medium is mainly composed of polycarbonate, so it has high heat resistance against the temperature rise that occurs during laser engraving, and the laser coloring layer to be laser engraved is sandwiched between the retroreflective printing layer and the concealing layer 22, making it difficult to physically cut and tamper with the structure.

<Embodiment 2>
5A shows a cross-sectional structure of the counterfeit prevention medium 2 according to claim 2 after laser engraving. The difference from embodiment 1 shown in FIG. 4A is that a color pattern layer 31 is formed between the laser coloring layer 12 and the concealing layer 22.

According to this embodiment, in addition to the latent image of the laser coloring layer 12a formed on the retroreflective layer 21, the colored pattern formed by the color pattern layer 31 can also be observed under flash photography as in the examples described below, making it possible to include a variety of identification elements.

<Embodiment 3>
Fig. 6A shows a cross-sectional structure after laser engraving of the counterfeit prevention medium 3 described in claim 3. The difference from embodiment 1 shown in Fig. 4A is that it has a concealing layer 23 in which a part of the concealing layer 22 is replaced with black ink that transmits infrared rays of a specific wavelength.

According to this embodiment, different latent images can be observed by selecting the light source wavelength for observation as in the examples described below, and a greater variety of identification elements can be included to improve security.

The detailed configuration of each of the above components is explained below.

<Core layer>
The core layer 11 contains an amorphous resin as a main component. The core layer 11 is, for example, white in color. The main component of the core layer 11 is a component having the highest content rate among the components constituting the core layer 11, and is, for example, a component having a content rate of 50 mass% or more in the core layer 11.

Specifically, the core layer 11 preferably contains polycarbonate or a polymer alloy of polycarbonate and amorphous polyester as a main component. Amorphous polyester and polycarbonate are examples of amorphous resins. Examples of amorphous polyesters include copolymers of terephthalic acid, cyclohexanedimethanol, and ethylene glycol, copolymers of terephthalic acid, isophthalic acid, and ethylene glycol, polyethylene terephthalate, and polybutylene terephthalate. The polymer constituting the core layer 11 may be crosslinked with isocyanate or the like.

In addition, talc or silica may be added to the material forming the core layer 11 to adjust the fluidity during molding, and titanium dioxide may be added to the material forming the core layer 11 to improve the whiteness.

<Laser coloring layer>
The laser coloring layer 12 contains polycarbonate or a polymer alloy of polycarbonate and amorphous polyester as a main component, and has laser colorability that irreversibly colors when irradiated with laser light. The main component of the laser coloring layer 12 is a component that has the highest content among the components that make up the laser coloring layer 12, and is, for example, a component that has a content of 50 mass % or more in the laser coloring layer 12. The thickness of the laser coloring layer is preferably 50 to 200 μm.

The main component of the laser coloring layer 12 contains, for example, carbon as a component having laser coloring properties. The laser coloring layer 12 generates heat by absorbing the laser light, and the heat causes carbonization, so that the laser coloring layer 12 turns black, becoming the laser coloring layer 12a as shown in Fig. 4A. For example, a YAG laser, a YVO4 laser, a _Co2 laser, etc., are used as the laser.

<Overlay Layer>
The overlay layer 13 contains, as a main component, polycarbonate or a polymer alloy of polycarbonate and amorphous polyester. The overlay layer 13 has sufficient transparency in the visible light region, the observation light wavelength region, and the laser light wavelength region used for laser engraving. The main component of the overlay layer 13 is a component having the highest content among the components constituting the overlay layer 13, for example, a component having a content of 50 mass% or more in the overlay layer 13.

<Retroreflective Layer>
The retroreflective layer 21 is formed by a printing method such as screen printing using ink mainly containing glass beads. Examples of drying methods after printing include hot air drying, and drying by irradiation with infrared rays or ultraviolet rays.

<Color pattern layer>
Dyes or pigments are used to color the ink used to print the color pattern layer 31. Metal pigments such as aluminum, titanium oxide, brass, and pearl pigments may also be used as pigments. Resins contained in the ink include vinyl chloride, vinyl acetate, polyvinyl alcohol, polyester, polyurethane, polycarbonate, acrylic resins, epoxy resins, ABS, copolymers thereof, polymer alloys, and the like.

If the ink is a solvent-based ink or a water-based ink, hot air drying is used among the drying methods described above, and if the ink is an ultraviolet-curable ink, curing by ultraviolet light irradiation is used among the drying methods described above.

<Hidden Layer>
The concealing layer 22 must be a dark color to conceal the variable information drawn directly underneath so that it cannot be seen with the naked eye, and must transmit flash light for flash photography and laser light for laser engraving. For these reasons, it is preferable to use a mixed black ink.

In addition, as shown in the third embodiment, the security effect can be enhanced by forming a pattern that appropriately combines different materials from the mixed ink, such as black ink or carbon black, which transmits infrared rays of a specific wavelength.

The black ink that transmits infrared rays of a specific wavelength has a 100 percent transmittance for wavelengths longer than a certain wavelength, and conversely, has the characteristic of absorbing light of a shorter wavelength. The certain wavelength refers to, for example, 700 nm, 900 nm, 1000 nm, etc.

Example 1
For the first embodiment, a counterfeit prevention device of the present invention was produced under the following conditions, the details of which will be described with reference to FIG.

(Sheet creation) A laser coloring polycarbonate sheet of about 100 μm was prepared as the laser coloring layer 12, and a retroreflective layer 21 was formed on one side by screen printing in the area shown as a white square surrounded by an ellipse in the lower part of Figure 4B. In addition, a concealing layer 22 was formed on the other side by screen printing in the area shown as an ellipse in Figure 4B so that the retroreflective layer 21 was completely hidden.

(Card Creation) The core sheet which is the core layer 11, the laser coloring sheet, and the overlay sheet which is the overlay layer 13 were layered in this order and thermally laminated to create a card.

The layer structure is not limited to this three-layer structure, but can be a five-layer structure by laminating a laser coloring sheet and an overlay sheet on both sides of the core sheet. An IC inlet can also be incorporated. If necessary, a base print can be applied to the overlay sheet or a hologram can be transferred.

(Laser engraving) A latent image was formed by drawing the character string to be concealed (the part indicated by "ABCDE" in the lower right of Figure 4B) on the part of the card covered with the concealing layer from the overlay layer side. A face photograph or a QR code (registered trademark) may be drawn instead of the character string.

Although not shown in the figure, it is also possible to simultaneously irradiate the laser light onto areas without a concealing layer, rendering variable information such as a facial photograph or ID information as a real image.

(Verification) When a laser-engraved card is viewed under a normal light source, only the concealing layer is visible, as shown in the top right of Figure 4B, and the latent image covered by the concealing layer cannot be seen.

However, when a photograph is taken using a strong light, such as the flash of a smartphone, the light passes through the concealing layer and reaches the retroreflective layer, where it is retroreflected, and the contrast between the areas that have turned black due to the laser engraving and absorb the light allows the hidden text to be seen, as shown in the lower right of Figure 4B.

In addition to visually inspecting the captured image, the captured image information can also be used for verification in conjunction with other information using OCR and other image analysis tools.

As described above, in Example 1, the latent image formed by laser engraving, which cannot be observed with the naked eye, could be easily verified using only the flashlight and digital camera equipped on the smartphone.

Example 2
In the second embodiment, a counterfeit prevention device of the present invention was produced under the following conditions, the details of which will be described with reference to FIG.

(Sheet Creation) A laser coloring polycarbonate sheet of about 100 μm was prepared as the laser coloring layer 12, and a retroreflective layer 21 was formed on one side by screen printing in the white square area surrounded by the ellipse in the lower part of Figure 5B. On the other side, a color pattern layer 31 of a specified color was first printed in the star-shaped area in the lower part of Figure 5B.

Furthermore, a concealing layer 22 was formed on top of it by screen printing in the elliptical portion shown in Figure 5B so that the color pattern layer 31 and the retroreflective layer 21 were completely hidden.

(Card creation) The card formation process was carried out in the same manner as in Example 1.

(Laser engraving) A latent image was formed by drawing a face photograph as a concealing pattern on the part of the card covered with the concealing layer from the overlay layer side. The latent image is not limited to a face photograph; it may also be a character string or a QR code (registered trademark).

Although not shown, it is also possible to simultaneously irradiate the laser light onto areas without a concealing layer, to render variable information such as ID information as a real image.

(Verification) When a laser-engraved card is viewed under a normal light source, only the concealing layer is visible, as shown in the top right of Figure 5B, and the latent image covered by the concealing layer cannot be seen.

However, when a photograph is taken using strong light such as a flash, the concealed photograph of the face and the star-shaped pattern can be observed due to the contrast between the light that passes through the concealing layer and reaches the retroreflective layer, the areas that have turned black and absorbed the light due to the laser engraving, and the areas that emit a specified color due to the color pattern layer, as shown in the lower right of Figure 5B.

As described above, in Example 2, the color pattern layer, which cannot be seen with the naked eye, and the latent image formed by laser engraving could be easily verified using only the flashlight and digital camera equipped on the smartphone.

Example 3
In the third embodiment, a counterfeit prevention device of the present invention was produced under the following conditions, the details of which will be described with reference to FIG.

(Sheet creation) A laser coloring polycarbonate sheet of about 100 μm was prepared as the laser coloring layer 12, and a retroreflective layer 21 was formed on one side by screen printing in the area shown as a white square surrounded by an oval in the middle of Figure 6B.

On the other side, a first concealing layer 22 is formed by screen printing in the upper half of the ellipse in the upper part of Figure 6B using mixed black ink that transmits light with wavelengths of 800 nm or more, and a second concealing layer 23 is formed by screen printing in the lower half of the ellipse in the upper part of Figure 6B using a special black material that transmits light with wavelengths of 900 nm or more, both of which cover and conceal the retroreflective layer 21.

(Card creation) The card formation process was carried out in the same manner as in Example 1.

(Laser engraving) A latent image was formed by drawing the character strings to be concealed (the part shown as "ABCD" and "1234" in the middle right of Figure 6B) on the part of the card covered with the concealing layer from the overlay layer side. The character string "ABCD" is concealed by the concealing layer 22, and the character string "1234" is concealed by the concealing layer 23.

Although not shown, it is also possible to simultaneously irradiate the laser light onto areas without a concealing layer, to render variable information such as ID information as a real image.

(Verification) When a laser-engraved card is viewed under a normal light source, only the concealing layer is visible, as shown in the top right of Figure 6B, and the latent image covered by the concealing layer cannot be seen. However, when a photo is taken using strong light such as a flash, the contrast between the light that passes through the concealing layer and reaches the retroreflective layer, and the areas that have turned black and absorbed the light due to the laser engraving, allows the hidden text to be seen, as shown in the middle right of Figure 6B.

In addition, a verification device is prepared that is made up of an LED light source with a wavelength of 850 nm and a photographing device equipped with a filter that absorbs wavelengths of 800 nm or less. When the card is observed with this device, the first concealing layer 22 transmits 850 nm light, so the character string "ABCD" drawn underneath can be observed, but the second concealing layer 23 absorbs 850 nm light and is observed to remain black, so the character string "1234" drawn underneath cannot be observed, resulting in an image like the one shown in the lower right of Figure 6B.

As described above, in Example 3, the latent image formed by laser engraving, which cannot be observed by the naked eye, can be easily verified using only the flashlight and digital camera equipped on the smartphone, and under special conditions that limit the observation wavelength, only specific latent images can be observed, making this an application example with higher security.

1 Counterfeit prevention medium of embodiment 1 2 Counterfeit prevention medium of embodiment 2 3 Counterfeit prevention medium of embodiment 3 11 Core layer 12 Laser coloring layer 12a Colored laser coloring layer 13 Overlay layer 22 Concealing layer or first concealing layer 23 Second concealing layer 31 Color pattern layer

Claims (4)

At least a core layer mainly made of polycarbonate resin, a laser coloring layer mainly made of polycarbonate resin, and an overlay layer mainly made of polycarbonate resin are laminated in this order;
A retroreflective layer is provided in a partial area between the core layer and the laser coloring layer,
A counterfeit prevention medium, comprising a concealment layer between said laser coloring layer and said overlay layer, said concealment layer blocking visible light weaker than flash light and transmitting infrared laser light in a partial area. The counterfeit prevention medium according to claim 1, characterized in that a pattern layer is sandwiched between the concealing layer and the laser coloring layer. The counterfeit prevention medium according to claim 1 or 2, characterized in that the concealing layer is either a mixed-color black ink, a black material that absorbs specific wavelengths, or carbon black, or is made by combining these materials in a predetermined pattern. The counterfeit prevention medium according to any one of claims 1 to 3, characterized in that variable information is recorded as a latent image in the laser coloring layer by laser light drawing.