JP2023178857A - Forgery prevention medium and verification method thereof - Google Patents

Abstract

To provide a forgery prevention medium at low cost which can easily determine authenticity with high accuracy.SOLUTION: According to an embodiment, a forgery prevention medium comprises: a base material; and an ink layer which is arranged on the base material and contains at least either of a dye or a pigment having a perylene framework, wherein the ink layer comprises: a first part containing a pigment in first concentration per unit area on the base material; and a second part containing a pigment in second concentration higher than the first concentration per unit area on the base material, the ink layer is observed in a first color when first observation light reflects on the ink layer, the first part is observed in a second color and the second part is observed in a third color which can be identified from the second color when second observation light passes through the ink layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to an anti-counterfeiting medium and a method for verifying the same.

Conventionally, various techniques for preventing forgery have been disclosed.

For example, Patent Document 1 discloses a technique in which ink, such as OVI ink and color shift ink, whose color changes depending on the viewing angle is applied to prevent counterfeiting.

Additionally, Patent Documents 2 and 3 disclose techniques for applying ink, such as metallic ink, whose color appears different depending on the lighting used, for counterfeit prevention.

Furthermore, techniques are also known in which multilayer deposited films, cholesteric liquid crystals, and device detection inks are applied to prevent counterfeiting.

Patent No. 4172199 Japanese Patent Application Publication No. 2001-159094 Japanese Unexamined Patent Publication No. 54-159004

However, these conventional techniques related to counterfeit prevention have the following problems.

OVI ink changes color when tilted, but the color change is not clear. For this reason, in the counterfeit prevention method using OVI ink, authenticity cannot be determined with high reliability.

On the other hand, with metallic ink, the colors visible under normal light such as sunlight, fluorescent lights, and incandescent bulbs, and the colors seen through a desired filter or under a light source with a desired spectral energy distribution are clearly visible. Because of the difference, it can be said that it is more suitable for authenticity determination than OVI ink. However, in order to obtain clear color changes, a special light source is required. For this reason, a counterfeit prevention method using metallic ink cannot be realized at low cost.

Furthermore, multilayer deposited films and cholesteric liquid crystals are expensive in material cost and manufacturing cost. Therefore, a counterfeit prevention method using a multilayer deposited film or a cholesteric liquid crystal cannot be realized at low cost.

Additionally, anti-counterfeiting technology using device-detecting ink requires special detectors. Therefore, the manufacturing cost of this detector again prevents it from being realized inexpensively. Further, even if this detector is manufactured, it can only be used by people who can operate it, and its versatility is poor.

In addition, smartphone authentication (referred to as "smartphone authentication"), which has evolved significantly in recent years, is applied to prevent forgery. Images of the subject are taken using the smartphone camera, and authenticity is determined based on the images. It is also possible to do so. However, when performing smartphone authentication, a specific application must be downloaded to the user's smartphone, which is time-consuming for the user. Further, even if a user downloads an application to his or her smartphone, since the orientation and angle of the camera differs from user to user, it is not possible to perform authenticity determination with high reliability.

The present invention was made in view of the above circumstances, and aims to provide a counterfeit prevention medium that is inexpensive, highly accurate, and can easily determine authenticity, and a verification method thereof. do.

In order to achieve the above object, the present invention takes the following measures.

That is, the first aspect of the present invention includes a base material and an ink layer disposed on the base material and containing at least one of a dye or a pigment having a perylene skeleton, and the ink layer is arranged on the base material. a first region containing pigment at a first concentration per unit area on the substrate; and a second region containing pigment at a second concentration higher than the first concentration per unit area on the substrate, and the first observation light is When reflected on the ink layer, the ink layer is observed in the first color, and when the second observation light is transmitted through the ink layer, the first region is observed in the second color, and the second region is observed in the second color. It is an anti-counterfeiting medium that is observed in a third color that is distinguishable from the original color.

A second aspect of the present invention is the anti-counterfeiting medium of the first aspect, in which the first portion and the second portion have the same thickness in the direction perpendicular to the main surface of the base material.

A third aspect of the present invention is the anti-counterfeiting medium of the first aspect, in which the first portion and the second portion have different thicknesses in a direction perpendicular to the main surface of the base material.

A fourth aspect of the present invention is the anti-counterfeiting medium according to the first or second aspect, wherein the first color is black, the second color is green, and the third color is red.

A fifth aspect of the present invention is the anti-counterfeiting medium according to the first or second aspect, in which the higher the second concentration, the more the third color shifts to the higher wavelength side.

A sixth aspect of the present invention is the anti-counterfeiting medium according to the first aspect, wherein the first observation light is light from a fluorescent lamp or sunlight, and the second observation light is light from a white light source. be.

In a seventh aspect of the present invention, the ink layer is a pigment having a perylene skeleton that shows black color in reflection, and has a transmittance of 0.2% or more and less than 10% near 540 nm and less than 10% near 780 nm at the first concentration. The anti-counterfeiting medium of the first aspect has a transmittance of 60% or more and less than 100%, and a transmittance at the second density of less than 0.2% near 540 nm and 40% or more and less than 100% near 780 nm.

An eighth aspect of the present invention is a method for verifying the anti-counterfeiting medium of the first aspect, in which when the first observation light is reflected on the ink layer, the ink layer is observed in the first color, When the second observation light is transmitted through the ink layer, if the first part is observed in the second color and the second part is observed in the third color, the anti-counterfeiting medium is determined to be genuine. However, in other cases, it is determined that the anti-counterfeiting medium is not genuine.

A ninth aspect of the present invention is the verification method according to the eighth aspect, wherein the first observation light is light from a fluorescent lamp or sunlight, and the second observation light is white light from a white light source. be.

A tenth aspect of the present invention is the verification method of the ninth aspect, wherein the white light source is a white LED mounted on a smartphone.

According to the present invention, it is possible to provide an anti-counterfeiting medium and a verification method thereof, which are inexpensive, highly accurate, and can easily determine authenticity.

FIG. 1 is a plan view showing an example of an anti-counterfeiting medium according to a first embodiment of the present invention. FIG. 2 is a side sectional view of the anti-counterfeiting medium taken along line XX' in FIG. FIG. 3 is a side sectional view corresponding to FIG. 2, showing a case where observation light is irradiated from a reflective light source and is reflected on an ink layer. FIG. 4 is a plan view corresponding to FIG. 1, showing a state observed by an observer when observation light from a reflected light source is reflected on an ink layer. FIG. 5 is a side sectional view corresponding to FIG. 2, showing a case where observation light is irradiated from a transmitted light source and passes through an ink layer. FIG. 6 is a plan view corresponding to FIG. 1, showing a state observed by an observer, in which observation light is irradiated from a transmitted light source and passes through an ink layer. FIG. 7 is a diagram showing the emission intensity characteristics of light emitted from the LED of the smartphone. FIG. 8 is a diagram showing the light transmission characteristics of a pigment having a perylene skeleton. FIG. 9 is a detailed diagram of the light transmission characteristics of a pigment having a perylene skeleton in the wavelength range from 380 nm to 630 nm in FIG. FIG. 10 is a general visibility curve. FIG. 11 is a side sectional view showing an example of an anti-counterfeiting medium according to the second embodiment of the present invention. FIG. 12 is a table showing the correlation between the number of layers and the L ^* a ^* b ^* value obtained by characteristic evaluation of the sample of Example 4. FIG. 13 is a diagram showing the correlation between the number of layers and the a ^* value obtained from FIG. 12. FIG. 14 is a general L ^* a ^* b ^* color space chromaticity diagram.

EMBODIMENT OF THE INVENTION Below, each embodiment of this invention is described with reference to drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be shown differently depending on the drawing. In the specification of this application and each figure, the same elements as those described above with respect to the existing figures are given the same reference numerals, and detailed explanations are omitted as appropriate.

(First embodiment)
FIG. 1 is a plan view showing an example of an anti-counterfeiting medium according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of the anti-counterfeiting medium taken along line XX' in FIG.

That is, the anti-counterfeiting medium 1 is constructed by disposing an ink layer 3 on a base material 2.

As the material for the base material 2, paper, plastic, wood, glass, resin, etc. that are transparent to white light from LEDs, etc. are used. Materials are selected.

The ink layer 3 includes a first part 3a containing a pigment at a first concentration per unit area on the base material 2, and a second part 3a containing a pigment at a second concentration higher than the first concentration per unit area on the base material 2. 3b.

The ink layer 3 is formed, for example, by a printing method such as an offset printing method, a gravure printing method, a screen printing method, and a flexographic printing method.

In the example shown in FIGS. 1 and 2, the ink layer 3 includes a first ink layer 3' having a circular planar shape and a star-shaped planar shape laminated on a part of the first ink layer 3'. A second ink layer 3'' having a second ink layer 3''.

In the example shown in FIGS. 1 and 2, the first region 3a is formed by a single layer of the first ink layer 3', and the second region 3b is formed by a single layer of the first ink layer 3' and the second ink layer 3''. It is formed by laminating multiple layers. Therefore, in the second region 3b, the pigment concentration per unit area on the base material 2 is higher than in the first region 3a.

FIG. 3 is a side sectional view corresponding to FIG. 2, showing a case where observation light is irradiated from a reflective light source and is reflected on an ink layer.

FIG. 4 is a plan view corresponding to FIG. 1, showing a state observed by an observer when observation light from a reflected light source is reflected on an ink layer.

The reflected light source 4' may be any light source, for example a fluorescent lamp or the sun. Therefore, as the observation light R, white light from a fluorescent lamp or sunlight from the sun can be used.

As shown in FIG. 3, when the observation light R is irradiated from the reflective light source 4' to the anti-counterfeiting medium 1 and the observation light R is reflected on the ink layer 3, as shown in FIG. is observed by observer K in the first color. The first color is, for example, black.

FIG. 5 is a side sectional view corresponding to FIG. 2, showing a case where observation light is irradiated from a transmitted light source and passes through an ink layer.

FIG. 6 is a plan view corresponding to FIG. 1, showing a state observed by an observer, in which observation light is irradiated from a transmitted light source and passes through an ink layer.

The transmitted light source 4'' can be, for example, a white light source such as a white LED installed in a smartphone. Therefore, the observation light T from the transmitted light source 4'' can be white light.

FIG. 7 is a diagram showing the emission intensity characteristics of light emitted from the LED of the smartphone.

There are two methods of emitting white light: a method of producing white light by combining the blue light of an LED and a phosphor that emits the complementary color yellow that is excited by the blue light, and a method of producing white light by combining the blue light of an LED and a phosphor that emits the complementary color yellow. Examples include methods of creating by combining.

As shown in FIG. 5, when the observation light T is irradiated from the transmitted light source 4'' to the anti-counterfeiting medium 1, and the observation light T is transmitted through the anti-counterfeiting ink layer 3, as shown in FIG. In the ink layer 3, the first region 3a is observed in a second color different from the first color, and the second region 3b is observed in a third color different from the first color and distinguishable from the second color. Ru. The second color is, for example, green, and the third color is, for example, red.

Note that although FIGS. 2, 3, and 5 show examples in which the second portion 3b is formed of two layers, the first ink layer 3' and the second ink layer 3'', the second portion 3b is 3b can also be formed of three or more layers, and the larger the number of layers, the more the third color shifts to the higher wavelength side. That is, when the third color is red, the larger the number of layers, the redder the color becomes.

Materials for the ink layer 3 having such characteristics include those that exhibit black color in reflection, have a transmittance of 0.2% or more and less than 10% near 540 nm, and a transmittance of 60% or more near 780 nm when a single layer is used. In the case of a multilayer structure, a pigment having a perylene skeleton having a transmittance of less than 0.2% near 540 nm and a transmittance of 40% or more and less than 100% near 780 nm is suitable. Pigments having a perylene skeleton have the characteristic of exhibiting high transparency in the near-infrared region while being black in reflection. Furthermore, by changing the substituents, the transmission wavelength can be controlled.

The basis for the transmittance of the ink layer 3 made of a pigment having such a perylene skeleton is as follows.

That is, focusing on the transmittance near 540 nm, when the ink layer 3 is a single layer, the transmitted light will appear red if the transmittance is less than 0.2%. On the other hand, if the transmittance of the single layer is 10% or more, the green color will be seen too strongly, and even reflection will appear greenish. In addition, when the transmittance of a single layer is 10% or more, when a multilayer is used, the transmittance is unlikely to be less than 0.2%, making it difficult to visually recognize red color. Furthermore, if the transmittance of the multilayer is 0.2% or more, the color will appear green in transmission.

Focusing on the transmittance around 780 nm, when the ink layer 3 is a single layer, if the transmittance is less than 60%, the overall transmittance will be low, so it may be easier to see in red. . On the other hand, if the transmittance is less than 40%, the transmitted light will appear blackish, making it difficult to visually recognize red color.

FIGS. 8 and 9 are diagrams of light transmission characteristics of pigments having a perylene skeleton.

In particular, FIG. 9 is a detailed diagram of the light transmission characteristics of a pigment having a perylene skeleton in the wavelength range from 380 nm to 630 nm in FIG.

FIG. 10 is a general visibility curve.

In the case of single layer a, as shown in FIG. 8, the transmittance in the visible region is low overall, but as shown in FIG. 9, it shows a maximum value around 540 nm. Furthermore, according to the visibility curve shown in FIG. 10, humans perceive green light around 555 nm most strongly in bright places. Therefore, when the observation light T passes through the single layer a, it becomes easily visible as a green color.

In the case of the multilayer b, the transmittance decreases overall as compared to the case of the single layer a, and in particular, as shown in FIG. 9, the transmittance near 540 nm decreases to almost 0%. Therefore, when the observation light T passes through the multilayer b, it becomes difficult to see in green and becomes easy to see in red around 780 nm.

Therefore, when the ink layer 3 formed by coating such a pigment is irradiated with observation light T from a transmitted light source 4'', the first portion 3a, which is a single layer a, turns green due to the transmission of the observation light T. However, the second portion 3b, which is the multilayer b, becomes visible in red.

In the ink layer 3 formed of a pigment having a perylene skeleton having such characteristics, a clearer color change between green and red can be confirmed than in an ink layer formed of OVI ink.

Next, a method for verifying the authenticity of the anti-counterfeiting medium 1 configured as described above will be described.

In this verification method, first, observation light R obtained from the sun or a fluorescent lamp is reflected on the anti-counterfeit medium 1, which is the object to be inspected, as illustrated in FIG.

As a result, when the observer K observes that the ink layer 3 becomes black, as illustrated in FIG. 4, the observer K then uses, for example, a smartphone as a light source, as illustrated in FIG. 4'' is placed on the back side of the subject, and observation light T is irradiated from the LED of the smartphone toward the subject and transmitted through the ink layer 3.

As a result, the ink layer 3, which was displayed in black as illustrated in FIG. When the observer K observes that the designated design is displayed, the observer K determines that this subject is genuine.

On the other hand, even if the ink layer 3 is not displayed black due to the reflection by the observation light R, or even if the ink layer 3 is displayed black due to the reflection by the observation light R, due to the transmission by the observation light T, If the ink layer 3 is not displayed in two distinguishable colors, such as green and red, in a pre-specified design, the observer K determines that the object is not genuine.

As described above, this verification method uses the color shift effect caused by reflection and transmission of light, and therefore does not require any special verification equipment, and can be realized at low cost and easily. This verification method requires reflected light and transmitted light, but sunlight can be used as reflected light, and an LED installed in a smartphone can be used as transmitted light, so a special light source is required. There's no need. Furthermore, since the authenticity can be determined through visual confirmation by the observer K, anyone can easily, inexpensively, and easily perform highly accurate authenticity determination without using any special application.

(Second embodiment)
FIG. 11 is a side sectional view showing an example of an anti-counterfeiting medium according to the second embodiment of the present invention.

The anti-counterfeiting medium 1A according to the second embodiment is a modification of the anti-counterfeiting medium 1 according to the first embodiment.

In the anti-counterfeiting medium 1A as well, the ink layer 3 is arranged on the base material 2, and the ink layer 3 includes a first region 3a containing pigment at a first concentration per unit area on the base material 2 and a first region 3a on the base material 2 containing a first concentration of pigment per unit area. and a second region 3b containing pigment at a second concentration higher than the first concentration per unit area. The first region 3a is formed by the first ink layer 3', as in the case of the anti-counterfeiting medium 1.

On the other hand, regarding the second portion 3b, in the anti-counterfeiting medium 1, it was realized by a multi-layer structure consisting of the first ink layer 3' and the second ink layer 3'', but in the anti-counterfeiting medium 1A, the third ink layer Realized by a single layer of 3'''. However, the third ink layer 3''' contains pigment at a higher concentration than the first ink layer 3'.

Even with such a configuration, the first part 3a containing the pigment at the first concentration per unit area on the base material 2, and the first part 3a containing the pigment at the second concentration higher than the first concentration per unit area on the base material 2. The ink layer 3 including the two portions 3b can be realized.

Further, according to such a configuration, unlike the anti-counterfeiting medium 1, the heights of the first portion 3a and the second portion 3b can be made equal, and a flat ink layer 3 can be realized. For example, when the ink layer 3 includes the second portion 3b having a star-shaped planar shape as shown in the plan view of FIG. 3''') on the base material 2, and then print the first portion 3a (first ink layer 3') around it so that the planar shape of the ink layer 3 is circular. .

Even with such a configuration, the ink layer 3 is displayed in black due to the reflection of the observation light R, and the first portion 3a is displayed in black due to the transmission of the observation light T, as described in the first embodiment. Since the second part 3b is displayed in green and the second part 3b is displayed in red, it can be effectively used for the verification method described in the first embodiment.

Next, Examples 1 to 4 in which samples of the anti-counterfeit medium 1 were actually created and the characteristics of the samples were evaluated will be described.

In Example 1, the ink layer 3 was formed using an ink containing a perylene material as a pigment under the conditions shown below.
Base material: Transparent PET film Pigment: Perylene-based material Ink: UV curable flexo ink Pigment concentration: 20%
Printing method: The ink layer 3 was formed by printing a 5 μm area in a single layer to form a first region 3a, and printing a 10 μm region in two passes to form a second region b.
Characteristic evaluation (for genuine products): The ink layer 3 was displayed in black due to the reflection of the observation light R, and the first portion 3a was displayed in green and the second portion 3b was displayed in red due to the transmission of the observation light T. . Therefore, the anti-counterfeiting medium 1 having the ink layer 3 formed in Example 1 can be determined to be a genuine product.
Characteristic evaluation (in case of counterfeit product): On the other hand, the anti-counterfeiting medium 1 having the ink layer 3 formed in Example 1 was copied using a copying machine. Since the copy is formed using the inkjet ink or toner of the copying machine instead of a predetermined ink, it appears black due to reflection, but the transmitted color is white, so it can be determined to be a counterfeit product.

In Example 2, the ink layer 3 was formed under the conditions shown below.
Base material: Transparent PET film Pigment: Perylene-based material Ink: UV curable flexo ink Pigment concentration: 20% and 40%
Printing method: Ink layer 3 was formed by separately painting a 20% pigment concentration area and a 40% pigment concentration area using a single layer having a thickness of 5 μm.
Characteristic evaluation: The ink layer 3 appears black when reflected, areas with a pigment concentration of 20% appear green, and areas with a pigment concentration of 40% appear red, so it can be determined that it is a genuine product.

In Example 3, the ink layer 3 was formed using an ink containing no pigment under the conditions shown below.
Base material: Transparent PET film Pigment: None Ink: UV-curable flexo black ink Printing method: Same as Example 1, print a 5 μm area in a single layer to form the first area 3a, and print twice to form a 10 μm area The ink layer 3 was formed by printing the area as the second area b.
Characteristic evaluation: The ink layer 3 was displayed as black due to the reflection of the observation light R, but was displayed as white due to the transmission of the observation light T. Therefore, it can be determined that the anti-counterfeiting medium 1 having the ink layer 3 formed in Example 3 is a counterfeit product.

In Example 4, as in Example 1, ink layers 3 having different numbers of layers were formed using ink containing a perylene material as a pigment.
Base material: Transparent PET film Pigment: Perylene-based material Ink: UV curable flexo ink Pigment concentration: 20%
Printing method: Samples of 1st to 5th layers were prepared, each having a single layer thickness of 3 μm.
Characteristic evaluation: The ink layer 3 is displayed as black due to the reflection of the observation light R, and the 1st to 2nd layers are displayed as yellowish green and the 3rd to 5th layers are displayed as yellowish red due to the transmission of the observation light T. Ta.

FIG. 12 is a table showing the correlation between the number of layers and the L ^* a ^* b ^* value obtained by characteristic evaluation of the sample of Example 4.

FIG. 13 is a diagram showing the correlation between the number of layers and the a ^* value obtained from FIG. 12.

FIG. 14 is a general L ^* a ^* b ^* color space chromaticity diagram.

As shown in FIGS. 12 and 13, it was found that increasing the number of layers (ie, increasing the pigment concentration per unit area) shifts the a ^* value in the + direction. This corresponds to a shift from green to red in the L ^* a ^* b ^* color system shown in FIG.

Thus, according to Example 4, the higher the concentration of the pigment contained in the second region 3b of the ink layer 3, the higher the wavelength of the red color observed in the second region 3b due to the transmission of the observation light T. It was confirmed that there was a shift to

Although the best mode for carrying out the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to this configuration. Those skilled in the art will be able to come up with various changes and modifications within the scope of the technical idea as claimed in the claims, and these changes and modifications will also fall within the technical scope of the present invention. It is understood that it belongs to

1, 1A... anti-counterfeiting medium, 2... base material, 3... ink layer, 3'... first ink layer, 3''... second ink layer, 3'''... third ink layer , 3a...first part, 3b...second part, 4'...reflected light source, 4''...transmitted light source, a...single layer, b...multilayer, K...observer, R...・Observation light, T...Observation light

Claims (10)

base material and
an ink layer disposed on the base material and containing at least one of a dye or a pigment having a perylene skeleton;
The ink layer includes a first part containing a pigment at a first concentration per unit area on the base material, and a second part containing a pigment at a second concentration higher than the first concentration per unit area on the base material. including
When the first observation light is reflected on the ink layer, the ink layer is observed in a first color,
When the second observation light passes through the ink layer, the first part is observed in a second color, and the second part is observed in a third color distinguishable from the second color. Prevention medium. The anti-counterfeiting medium according to claim 1, wherein the first portion and the second portion have the same thickness in a direction perpendicular to the main surface of the base material. The anti-counterfeiting medium according to claim 1, wherein the first portion and the second portion have different thicknesses in a direction perpendicular to the main surface of the base material. The counterfeit prevention medium according to claim 1 or 2, wherein the first color is black, the second color is green, and the third color is red. The anti-counterfeiting medium according to claim 1 or 2, wherein the higher the second density, the more the third color shifts to a higher wavelength side. The anti-counterfeiting medium according to claim 1, wherein the first observation light is light from a fluorescent lamp or sunlight, and the second observation light is light from a white light source. The ink layer is a pigment having the perylene skeleton that shows black color when reflected,
The transmittance at the first concentration is 0.2% or more and less than 10% near 540 nm and 60% or more and less than 100% near 780 nm,
The anti-counterfeiting medium according to claim 1, wherein the transmittance at the second density is less than 0.2% near 540 nm and 40% or more and less than 100% near 780 nm. A method for verifying an anti-counterfeiting medium according to claim 1, comprising:
When the first observation light is reflected on the ink layer, the ink layer is observed in the first color, and when the second observation light is transmitted through the ink layer, the ink layer is observed in the first color. If the part is observed in the second color and the second part is observed in the third color, the anti-counterfeiting medium is determined to be authentic; otherwise, the anti-counterfeiting medium is determined to be authentic. A verification method to determine that it is not. 9. The verification method according to claim 8, wherein the first observation light is light from a fluorescent lamp or sunlight, and the second observation light is white light from a white light source. The verification method according to claim 9, wherein the white light source is a white LED mounted on a smartphone.