JP2001039100A - Falsification preventing method and falsification preventing medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a falsification preventing method and a falsification preventing medium, in which a large number of times of judgments between the true and the false and possible, which has no limitation on endurance and the finesse of images, which requires no specified detecting device and by which the true or the false can be easily judged. SOLUTION: A medium 1, in which a latent image 23 formed through the utilization of orientation so as to be visually recognizable through a polarizing film and to be impossible to or difficult to visually recognize through no polarizing film on the latent image forming layer 13, which is provided on a light reflecting layer 12, of the medium, is employed. The material of the latent image formed layer is a polymeric material, in which a latent image formable through the orientation caused by an external force can be provided, and a polymeric thermotropic liquid crystal material, in which a latent image is provided by developing an orientation under heat and pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forgery prevention method and a medium using a latent image for displaying a hidden character or a hidden pattern, and more particularly to a true / false determination of whether or not the product is a counterfeit. The present invention relates to a forgery prevention method and a forgery prevention medium that can easily perform the forgery prevention.

[0002]

2. Description of the Related Art Conventionally, there are various methods using a latent image to prevent forgery. For example, 1) Hidden characters etc. are inserted using the gap of the line pitch,
A line drawing in which hidden characters appear by hiding the lines, 2) Print a transparent ink medium with a filler, and rub the part with a pencil. Pencil powder adheres to the printed part and the hidden characters There is a pencil out print (deco mat) that appears. However, since these latent images are deciphered when viewed closely, they are used for play rather than forgery prevention methods using full-scale latent images.

[0003] 3) A method of forming a latent image using a white or colorless and transparent irreversible thermosensitive coloring ink that develops color by applying heat requires a heat source device to display the latent image. Since an image displayed once cannot be erased, its use is limited. 4) A method of displaying a latent image by printing a white ink containing a filler harder than a metal such as titanium oxide on a white paper and rubbing it with a coin or the like is a visual method by providing a mat-like varnish. Although this is eliminated, the use of the latent image is limited because it can be displayed only once. That is, the above methods 3) and 4) are limited to one-time use.

[0004] Further, as a method for preventing forgery by a latent image which can be repeatedly displayed, 5) reversible thermosensitive coloring ink (thermochromic ink)
There is a method using. The thermochromic ink reversibly develops or decolors when heated, and returns to its original state after being left for a while. This ink is used as a latent image or for concealing an image, but its use is limited because of its low resistance, especially heat resistance. 6) Photochromic ink is an ink that develops color when irradiated with light, particularly ultraviolet light, and is used as a latent image by using it as a white or colorless and transparent ink. Limited. 7) The fluorescent ink is an ink that emits light when irradiated with ultraviolet light, and is used as a latent image by being used as a white or colorless transparent ink. The fluorescent ink includes an organic type and an inorganic type. The organic type emits light only when it is contained in a very small amount in the printing ink, but its use is limited due to its low light resistance. Further, the inorganic type needs to be contained in a large amount in the printing ink (about 10 to 20%), and is easily visible as a latent image by visual observation. That is, the methods 5), 6) and 7) are restricted in terms of durability.

Another method for preventing forgery with a latent image that can be repeatedly displayed is 8) a method of forming a latent image by using moire (interference fringes) of halftone dots or lines. In this method, a latent image is formed by partially changing the pitch or angle of a halftone dot or a line, and an image appears by overlaying an orderly arranged halftone dot or a line of transparent film on this latent image. is there. In this method, the display can be easily repeated with the transparent film, and there is no limitation in terms of durability, but there is a problem that a complicated image cannot be formed.

As another method of preventing forgery using a latent image which can be repeatedly displayed, there is a method 9) using a latent image using magnetic ink. This is to form a latent image by magnetizing a magnetic layer having a coercive force (about 300 Oe or more) capable of magnetic recording in a pattern.
This is a method in which a magnetized portion is displayed as an image by sprinkling iron powder on the magnetic layer. However, in this method, the latent image can be easily rewritten and forged, and the process of displaying the latent image is complicated, and a specific detection device is required. 10) There is a method in which a latent image is formed with ink that absorbs infrared light, and a layer that transmits infrared light without transmitting visible light is provided on the latent image. However, in order to display this latent image, an infrared camera or the like is required, and the apparatus becomes large. In addition, there is a method using an ink (IV ink) which is white or colorless in the visible region but absorbs in the infrared region. An infrared camera or the like is also required.

That is, the above methods 9) and 10) are methods capable of repeated display and are not restricted in terms of durability and image definition, but a specific detection device is required for displaying a latent image. It is what becomes.

[0008]

As described above, the methods using the above-described latent image for preventing forgery have different problems. The present invention has solved the above problems, and when using a latent image to prevent forgery, authenticity determination can be performed many times, resistance, not restricted in terms of image definition, and, An object of the present invention is to provide a forgery prevention method and a forgery prevention medium that do not require a specific detection device for the interpretation and that can easily determine the authenticity of forgery.

[0009]

According to the present invention, there is provided a medium having a latent image forming layer provided on a light reflecting layer, wherein the latent image forming layer is visually recognizable through a polarizing film. A forgery prevention method characterized by using a medium provided with a latent image formed by using orientation so as to be invisible or difficult to be visually recognized.

Further, according to the present invention, the latent image forming layer of a medium having a latent image forming layer provided on a light reflecting layer is visually recognizable through a polarizing film and visually recognizable without a polarizing film. A forgery prevention medium characterized in that a latent image formed using orientation is provided so as to be impossible or difficult to view.

The present invention also provides the forgery prevention medium according to the above invention, wherein the material of the latent image forming layer is a polymer material capable of providing a latent image which can be formed by being oriented by an external force. This is a forgery prevention medium characterized by the following. Further, the present invention is the forgery prevention medium according to the above invention, wherein the material of the latent image forming layer is a polymer liquid crystal material.

According to the present invention, in the forgery prevention medium according to the present invention, the polymer liquid crystal material is a polymer liquid crystal material having a thermotropic property, and the latent image is provided by being oriented by heating and pressing. It is a forgery prevention medium characterized by the above. Further, the present invention is the forgery prevention medium according to the above invention, wherein a base material is provided below the light reflection layer.

[0013] The present invention also relates to a forgery prevention medium according to the above invention, wherein a protective layer is provided on the latent image forming layer. Further, the present invention is the forgery prevention medium according to the above invention, wherein the polarizing film is a circularly polarizing film.

[0014]

Embodiments of the present invention will be described below. FIG. 1 is a plan view showing an embodiment of a forgery prevention medium according to the present invention. FIG. 2 is a cross-sectional view showing one embodiment along the line XX ′ in FIG. As shown in FIGS. 1 and 2, the forgery prevention medium (1) has a latent image forming layer (13) provided on a light reflecting layer (12). In FIG. 2, (23) is a part of the latent image forming layer (13),
It is a portion (latent image) formed using the orientation such that it is visually recognizable through a polarizing film and visually invisible or difficult to visually recognize without a polarizing film. By selectively orienting the latent image forming layer, an image can be provided by an oriented portion and a non-oriented portion. In addition, if necessary, the orientation may be solid.

The latent image (23) is formed by a latent image forming layer (13).
Are portions oriented by heat, electricity, magnetic energy, or the like in an image pattern. In FIG. 1, the anti-counterfeit medium (1) has a latent image (2
3) cannot be confirmed and can be seen only as a mere light reflection medium.

FIG. 3 is a plan view showing a state of reading the latent image (23) of the embodiment of the forgery prevention medium shown in FIG. FIG. 4 is a cross-sectional view showing a state when the latent image (23) shown by the XX ′ cross section in FIG. 3 is read. As shown in FIGS. 3 and 4, an image in which the latent image (23) can be visually recognized by superimposing the polarizing film (14) on the anti-counterfeit medium (1) and visually checking through the polarizing film (14). (23 ').

FIG. 5 is a diagram conceptually illustrating the state of the optical path when reading the anti-counterfeit medium according to the present invention. FIG.
As shown in the figure, the white light (56) from the light source (58) passes through the polarizing film (14) and becomes linearly polarized light, and the latent image (23) oriented in an image pattern which is a part of the latent image forming layer. Through the light reflection layer (1).
The light is reflected by 2) and transmitted again through the polarizing film (14) to become reflected light (57).

Since the intensity of the reflected light (57) varies depending on the wavelength, reflected light having various hues can be obtained. Further, the hue to be seen differs depending on the angle between the orientation direction of the polarizing film and the orientation direction of the latent image forming layer. The linearly polarized light that has passed through the other part of the latent image forming layer that is not oriented in the image pattern (not shown) is reflected by the light reflecting layer (12) without being changed to elliptically polarized light, and again the polarizing film (14). And becomes white reflected light.

FIG. 6 shows a protective layer (15) provided on the latent image forming layer (13) and a substrate (11) provided under the light reflecting layer (12) of the forgery prevention medium (1) shown in FIG. It is sectional drawing which shows an example of a forgery prevention medium. The protective layer (15) has a role of protecting the latent image forming layer (13) from external damage, and of preventing a latent image from being visually recognized by an image forming trace from heat pressure during image formation. The substrate (11) has a role of supporting the light reflecting layer (12) and the latent image forming layer (13) and reinforcing the strength.

As the substrate (11), synthetic resin films such as polyethylene terephthalate, polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, polystyrene, etc., natural resin films, synthetic paper,
Paper, a glass plate, or the like can be used alone or in a combined composite or the like.

The light reflection layer (12) is not particularly limited as long as it has light reflectivity, and a vapor deposition film of various metals and alloys, a sputtering film, and the like can be used. For example, Al, Cr, Ni, C as metals
u, Ag, etc., and Pt-Rh, Ni
-Cr and the like.

As the latent image forming layer (13), a polymer material such as polyolefin or polyester is used.
Further, as the polymer liquid crystal, those having a melting point of about 80 to 200 ° C. and exhibiting thermotropic property are preferable. For example, thermotropic substances such as polyester copolymer, polyether, polycarbonate, polyisocyanate, and polyglutamic acid ester are preferable. Polymer material exhibiting properties. The polymer material exhibiting thermotropic property to be the polymer liquid crystal layer can be formed by a known coating means such as a gravure printing method, a screen printing method, and a nozzle coater method. This polymer liquid crystal layer is formed in a random molecular state that does not have a specific crystal structure in a normal state of application.

Examples of the polarizing film (14) include polymer polycrystalline types such as a PVA-iodine type, a dichroic dye type, a metal or metal compound containing type, and a polyene type in which iodine is absorbed in a stretched PVA film. . In particular, PVA-iodine type and dichroic dye type are preferable. A typical example of the circularly polarizing film is a film in which a quarter-wave retardation film is laminated on the polarizing film (14).

The latent image (23) is a portion where the latent image forming layer (13) is oriented in a certain direction by external force such as heat, pressure, scratch, friction, light, electricity, magnetism, etc. By selectively orienting, it is possible to present an image-like state by the oriented part and the non-oriented part. As a method for forming a latent image, for example, heating with a hot stamp, a thermal head, a laser, or the like, and scratching with a brush, sandpaper, sandblast, or the like is possible.

As the protective layer (15), for example, acrylic resin, urethane resin, vinyl chloride resin-vinyl acetate copolymer resin, polyester resin, melamine resin,
Conventionally known thermoplastic resins such as epoxy resins, polystyrene resins, and polyimide resins, thermosetting resins, and ultraviolet or electron beam curing resins can be used alone or as a mixture.

Further, in order to prevent a print mark at the time of image formation by a thermal head or the like, a curing agent for crosslinking a resin, waxes such as polyethylene washes, carnauba wax, silicon wax, or calcium carbonate, zinc stearate, An extender such as silica, alumina, or talc, or an oil such as a silicone oil may be added within a range that does not impair the transparency. The resin used for the protective layer (15) is, for example, a gravure printing method, a screen printing method,
The coating can be performed by a printing means such as an offset printing method or a flexographic printing method, or a known coating means such as a nozzle coater method.

[0027]

The present invention will be described in detail with reference to the following examples. <Example 1> A light reflecting layer was formed by forming a film of Al to a thickness of about 60 nm on one surface of a polypropylene sheet having a thickness of 50 µm by a vacuum evaporation method, and rubbing the other surface with a nylon brush in one direction, and polarizing the entire surface. I had it. After masking the portion of this surface that wants to retain its polarization with acrylic resin using screen printing, rub it with a nylon brush in the direction perpendicular to the direction in which it was previously rubbed, and after eliminating the polarization of the unmasked portion And the acrylic resin was peeled off.

The anti-counterfeit medium obtained did not show any latent image by visual observation without a polarizing film, and appeared to be a mere metal-deposited film. The image was visible.

Example 2 100 μm P as a substrate
Using the ET film, the anti-counterfeit medium prepared in Example 1 was laminated from the Al deposition side to have strength. And
The surface on which the latent image was formed was coated with 3 μm by offset printing using an ultraviolet curable ink, and cured by an ultraviolet lamp to protect the latent image.

In the obtained anti-counterfeit medium, the latent image could not be visually recognized at all without visual observation through a polarizing film, and could be seen as a mere metal vapor-deposited film. A good image could be visually recognized.

Example 3 Al was formed as a metal film having a thickness of about 60 nm on a PET substrate having a thickness of 50 μm by vacuum evaporation to obtain a light reflecting layer. A latent image forming layer was formed thereon by a gravure method using a thermotropic polymer material ink. The drying temperature was 60 ° C., and the coating thickness was 0.5 μm. On this latent image forming layer, an anchor medium was applied by printing about 1 μm by offset printing, and further a top coat varnish was applied by printing about 2 μm by offset printing to obtain a protective layer.

To form a latent image pattern on the latent image forming layer of the forgery prevention medium thus obtained,
Alignment was performed by applying heat and pressure with a hot stamp at 0.2 ° C. for 0.2 seconds to obtain a forgery prevention medium having a latent image formed thereon. In the anti-counterfeit medium on which the obtained latent image was formed, the latent image could not be visually recognized at all without visual observation through a polarizing film, but could be seen as a mere metal-deposited film, but the pattern of the latent image was clear through visual observation through the polarizing film. And a good image could be visually recognized.

The composition of the used thermotropic polymer material ink is shown below. Polymer liquid crystal (Kiracol PLC-7003: manufactured by Asahi Denka Kogyo Co., Ltd.) 20 parts by weight Tetrahydrofuran 40 parts by weight Toluene 40 parts by weight The followings were used for anchor medium and top coat varnish, respectively. Anchor medium: FDS medium TPB (Toyo Ink Manufacturing Co., Ltd.) Top coat varnish: Matt OP varnish 3H (T & K Co., Ltd.)
(Manufactured by TOKA)

Example 4 In order to form a latent image pattern on the latent image forming layer of the anti-counterfeit medium obtained in the same manner as in Example 3, orientation was performed by printing with a thermal head to form a latent image. An anti-counterfeit medium was obtained. The anti-counterfeit medium on which the obtained latent image was formed, the latent image could not be visually recognized at all without visual observation through a circularly polarizing film, but could be seen as a mere metal vapor-deposited film. The image appeared clearly regardless of the angle and a good image could be visually recognized. Further, since the latent image pattern is formed by thermal head printing, an arbitrary pattern can be formed.

[0035]

According to the present invention, there is provided a method for preventing forgery of a medium using a latent image for forgery prevention, wherein the latent image forming layer of a medium having a latent image forming layer provided on a light reflection layer is provided with a polarizing film. Is a forgery prevention method using a medium provided with a latent image formed by using an orientation so as to be invisible or difficult to see by visual inspection without passing through a polarizing film. It is possible to judge the authenticity many times, it is not restricted in terms of durability and image definition, and it does not require a specific detection device for its interpretation, and it can easily judge the authenticity of forgery or not A forgery prevention method that can be performed.

Further, according to the present invention, in a medium using a latent image for preventing forgery, the latent image forming layer of a medium in which a latent image forming layer is provided on a light reflection layer is visually recognized through a polarizing film. A latent image formed using orientation is provided so as to be invisible or difficult to see by visual inspection without using a polarizing film. A forgery prevention medium that is not restricted in terms of image definition and does not require a specific detection device for its interpretation, and that can easily determine whether it is forgery or not.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a forgery prevention medium according to the present invention.

FIG. 2 is a cross-sectional view showing one embodiment along a line XX ′ in FIG. 1;

FIG. 3 is a plan view showing a state of reading a latent image of the embodiment of the forgery prevention medium shown in FIG. 1;

FIG. 4 is a cross-sectional view showing a state when the latent image shown by the XX ′ cross section in FIG. 3 is read.

FIG. 5 is a diagram conceptually illustrating a state of an optical path when reading a forgery prevention medium according to the present invention.

FIG. 6 is a cross-sectional view showing an example of a forgery prevention medium in which a protective layer is provided on the latent image forming layer of the forgery prevention medium shown in FIG. 2 and a base material is provided below the light reflection layer.

[Explanation of symbols]

 1 {forgery prevention medium 11} substrate 12} light reflection layer 13} latent image forming layer 14} polarizing film 15} protective layer 23} latent image 23 '{visible image 56} White light 57 ° Reflected light 58 ° Light source

Claims (8)

[Claims] 1. A latent image forming layer provided on a light reflecting layer of a medium, wherein the latent image forming layer is visually or visually invisible or difficult to visually recognize through a polarizing film. A forgery prevention method characterized by using a medium provided with a latent image formed using orientation. 2. A latent image forming layer of a medium having a latent image forming layer provided on a light reflecting layer, wherein the latent image forming layer is visually invisible or difficult to visually recognize through a polarizing film and not through a polarizing film. A forgery prevention medium characterized by having a latent image formed by utilizing orientation. 3. The forgery prevention medium according to claim 2, wherein the material of the latent image forming layer is a polymer material capable of providing a latent image that can be formed by being oriented by an external force. . 4. The forgery prevention medium according to claim 2, wherein the material of the latent image forming layer is a polymer liquid crystal material. 5. The forgery prevention device according to claim 4, wherein said polymer liquid crystal material is a polymer liquid crystal material having a thermotropic property, and said latent image is provided by being oriented by heating and pressing. Medium. 6. The forgery prevention medium according to claim 2, wherein a base material is provided under the light reflecting layer. 7. The forgery prevention medium according to claim 2, wherein a protective layer is provided on the latent image forming layer. 8. The anti-counterfeit medium according to claim 2, wherein the polarizing film is a circular polarizing film.