JP2009150968A - Forgery preventive medium and forgery preventive sticker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forgery preventive medium, wherein reflected colors change in accordance with the changes in viewing angle, and latent information such as characters and images is made visible by viewing through a polarizing filter prepared separately, so that the information can be checked, and to provide a forgery preventive sticker using the forgery preventive medium. <P>SOLUTION: The forgery preventive medium has a multi-layer thin film layer formed by laminating, on a transparent substrate, a plurality of thin films exhibiting different optical characteristics such as a ceramic thin film, a metal thin film, and a transparent resin thin film. At least on a part of the multi-layer thin film layer or the transparent substrate, a transparent retardation layer is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  According to the present invention, the reflected color changes according to the change in the viewing angle, and information such as characters and images that are formed into a latent image is displayed and confirmed by observing through a separately prepared polarizing filter. The present invention relates to an anti-counterfeit medium that can be protected and an anti-counterfeit seal using the anti-counterfeit medium.

  Conventionally, as a means for preventing counterfeiting, it is difficult to imitate the article itself, or it is possible to distinguish between genuine and counterfeit by attaching to the article proof that the article is genuine. There is a means to Typical examples of the latter include those using holograms such as relief holograms, diffraction gratings, and Lippmann holograms, which are frequently used in recent years, as materials for mounting on articles. Among them, for example, a relief hologram reflects the light intensity distribution of interference fringes as a change in fine irregularities, and supports the viewing angle (that is, supports the hologram) by light diffraction and interference in the fine irregularities. Color) (color change of reflected light) is generated in accordance with the angle at which the image is observed, and the visible color varies depending on the observation position. Therefore, by checking the presence or absence of such a phenomenon in an article to which a hologram is attached, it can be easily determined whether or not the article is genuine. However, in recent years, holograms such as those described above have become well known in terms of the principle of holograms, and since the structure of the hologram forming layer and the like is simple, it is becoming more easily counterfeited. The effect of is fading.

  On the other hand, as with this hologram, it is assumed that color shift (color change of reflected light) occurs due to the difference in viewing angle, and thin films made of ceramics, metals, etc. are laminated on the base material, and the optical characteristics of each thin film differ. There is a multilayer thin film laminated medium as described above (see, for example, Patent Document 1).

  Such a laminated medium utilizes the interference effect of light obtained by the combination of the optical characteristics and film thickness of each thin film, has reflection / transmission characteristics in a specific wavelength range, and has different observation positions. Different colors are visible. Therefore, in the same way as the hologram described above, the laminated medium having such a configuration can be easily determined whether or not the article is genuine by confirming the presence or absence of the change in the state of the article. . Incidentally, in such a laminated medium, since the change in color is difficult to understand if the substrate on which the multilayer thin film is formed is a transparent film, a dark colored layer such as black or a metallic reflective layer is used as the base of the multilayer thin film. A device is added to make the visibility more reliable by adding a film.

  In these color shifts (color changes in reflected light), color changes due to differences in viewing angle make it possible to determine whether a counterfeit is true or not, especially when copying illegally with a copier or color copier. Since it is impossible to reproduce the optical characteristics of the copy in the copy, it is difficult to forge / modify, and even if forgery / alteration is attempted, it acts to give up its use.

As an application form of the multilayer thin film that expresses such a color shift, it is supported on a medium, a seal, or a transfer foil, a transfer sheet, etc. There are methods that allow color shifts to be manifested. For the purpose of adding higher security, especially considering the layer structure, the seal carrying the multilayer thin film is difficult to peel off, or a structure such as a brittle seal that makes it difficult to regenerate after peeling. Once affixed to an article, it would be easy to see that some illegal operation was applied to the article in addition to counterfeiting by destroying part or all of the hologram when attempting to peel it off. There is also a method to make it possible to discriminate by.

  Furthermore, there is also a forgery prevention medium in which various colors can be seen on one surface by using the color shift effect of the multilayer thin film and embossing the thin film at a certain angle (see, for example, Patent Document 2). .

However, an effect similar to that of a multilayer thin film is also manifested in cholesteric liquid crystals, pearl pigments, and the like, and the effect of preventing counterfeiting has been reduced because it is obtained by materials usually used in the display industry and cosmetic industry.
JP-A-7-146650 (paragraph number 0021) JP 11-2224050 A (paragraph number 0009)

  The present invention has been made in view of the above-described problems, and in addition to the color shift effect obtained with a multilayer thin film layer, images and characters that are not normally visible by observing using a separately prepared polarizing filter. It is an object of the present invention to provide an anti-counterfeit medium and a forgery-preventing seal using the anti-counterfeit medium capable of confirming the above-described information and enabling higher-level authenticity determination than ever.

  In order to achieve the above object, the invention according to claim 1 is a multilayer thin film layer formed by laminating a plurality of thin films having different optical characteristics such as a ceramic thin film, a metal thin film, and a transparent resin thin film on a transparent substrate. And an anti-counterfeit medium characterized by having a transparent retardation layer on at least a part of the multilayer thin film layer or the transparent substrate.

  According to a second aspect of the present invention, in the anti-counterfeit medium according to the first aspect, the transparent retardation layer is formed by fixing a nematic or smectic liquid crystal.

  Furthermore, the invention described in claim 3 is the anti-counterfeit medium described in claim 1 or 2, wherein a light absorption layer is provided below the retardation layer.

  Furthermore, the invention according to claim 4 is the forgery prevention medium according to any one of claims 1 to 3, wherein the multilayer thin film layer is provided on at least a part of the transparent substrate. To do.

  Furthermore, the invention according to claim 5 is characterized in that in the forgery prevention medium according to any one of claims 1 to 4, a protective layer is provided so as to cover the retardation layer.

  Furthermore, the invention described in claim 6 is a forgery prevention seal characterized in that the counterfeit prevention medium according to any one of claims 1 to 5 has an adhesive layer on one surface.

  Since the anti-counterfeit medium and the anti-counterfeit seal of the present invention are observed by changing the color depending on the viewing angle, a desired anti-counterfeit effect can be expected, and this color change is created by a color copier or the like. Therefore, it is possible to prevent fraudulent acts such as forgery, falsification and alteration using a color copier.

  Furthermore, by observing through a separately prepared polarizing filter, the predetermined information that has been formed into a latent image can be confirmed, so that it can be expected that the effect of preventing forgery is further improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1, 2 and 4 show an embodiment of the anti-counterfeit medium of the present invention. FIG. 4 is an explanatory diagram showing a planar state of the anti-counterfeit medium 1, and FIG. 1 is an explanatory diagram showing a schematic cross-sectional configuration along line X-X 'of the anti-counterfeit medium 1 shown in FIG. FIG. 2 is an explanatory diagram showing a schematic cross-sectional configuration according to another embodiment of the forgery prevention medium of the present invention. FIG. 5 is an explanatory diagram showing a state when the anti-counterfeit medium 1 shown in FIG. 4 is observed through the polarizing filter 50 and the latent image information is visually recognized. FIG. 6 is an L * a * b * chromaticity diagram for explaining the state of color change in the multilayer thin film layer when the forgery prevention medium according to the present invention is observed while changing the viewing angle.

  The anti-counterfeit medium 1 shown in FIGS. 1 and 4 has a multilayer thin film layer 11 formed by laminating a plurality of thin films having different optical characteristics such as a ceramic thin film, a metal thin film, and a transparent resin thin film on a transparent substrate 10. A phase difference layer 12 is provided on a part of one surface of the multilayer thin film layer 11, and a light absorption layer 14 is provided on one surface of the transparent substrate 10, so that the phase difference layer 12 is further covered. Is provided with a protective layer 13.

  On the other hand, the anti-counterfeit medium shown in FIG. 2 has the same basic structure as the anti-counterfeit medium described above, but a light absorption layer is provided on the surface side of the transparent substrate 20 on which the multilayer thin film layer 21 is not laminated. Not different in that.

  On the other hand, FIG. 3 shows a schematic cross-sectional structure of the forgery prevention seal of the present invention. The anti-counterfeit seal shown here has the same basic structure as the anti-counterfeit medium shown in FIG. 1, but differs in that an adhesive layer 35 is further laminated on the light absorption layer 34.

  As the transparent base material 10, 20, and 30 constituting a part of the anti-counterfeit medium and the anti-counterfeit seal, triacetyl cellulose, polyethylene terephthalate, polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, polystyrene, etc. A transparent base material having a certain degree of rigidity and surface smoothness can be used. Of the above-described constituent materials, triacetyl cellulose is preferably used.

  The multilayer thin film layers 11, 21, and 31 provided on the transparent base materials 10, 20, and 30 are formed by laminating a plurality of thin films such as metal thin films, ceramic thin films, and transparent resin thin films that exhibit different optical aptitudes. Is.

As ceramics used as the constituent material of each thin film of the multilayer thin film layer, for example, Sb ₂ O ₃ (3.0 = refractive index n: the same shall apply hereinafter), Fe ₂ O ₃ (2.7), TiO ₂ (2. 6), CdS (2.6), CeO ₂ (2.3), ZnS (2.3), PbCl ₂ (2.3), CdO (2.2), Sb ₂ O ₃ (2.0), WO (2.0), SiO (2.0), Si ₂ O ₃ (2.5), In ₂ O ₃ (2.0), PbO (2.6), Ta ₂ O ₃ (2.4) ZnO (2.1), ZrO ₂ (2.0), MgO (1.6), SiO ₂ (1.5), MgF ₂ (1.4), CeF ₃ (1.6), CaF ₂ ( 1.3-1.4), AlF ₃ (1.6), Al ₂ O ₃ (1.6), GaO (1.7) and the like. Examples of the constituent material of the simple metal or alloy-based thin film include Al, Fe, Mg, Zn, Au, Ag, Cr, Ni, Cu, and Si. Examples of the constituent material of the low refractive index organic polymer thin film include polyethylene (1.51), polypropylene (1.49), polytetrafluoroethylene (1.35), and polymethyl methacrylate (1. 49), polystyrene (1.60) and the like.

  An appropriate material is selected from these constituent materials. For example, at least one kind of thin film made of a high refractive index material or a metal thin film having a transmittance of about 30% to 60%, at least one kind from a thin film made of a low refractive index material. By selecting these and alternately laminating them at a predetermined thickness, a multilayer thin film layer exhibiting a predetermined absorbability or reflectivity for visible light of a specific wavelength can be obtained. In short, considering the optical properties such as refractive index, reflectance, and transmittance, weather resistance, chemical resistance, interlayer adhesion, etc. from the above-described constituent materials, an appropriate constituent material is selected to form a thin film, A plurality of layers may be stacked to form a multilayer thin film layer. In general, the spectral characteristics of the multilayer thin film layer vary depending on the number of layers.

Another example of the multilayer thin film layer is a layer formed by laminating a plurality of high refractive index thin films and low refractive index thin films, more specifically, a high refractive index material having a refractive index of approximately 2 or more. And a plurality of low refractive index materials having a refractive index of about 5 with a predetermined film thickness and a predetermined combination. The layer thickness is in the range of about 50 to 2000 nm, and a thin film made of a high refractive index material or a metal material, such as ZnS, TiO ₂ , ZrO ₂ , In ₂ O ₃ , SnO, ITO, CeO ₂ , ZnO, Ta _2. A thin film made of O ₃ , Al, Fe, Mg, Zn, Au, Ag, Cr, Ni, Cu, Si, etc., and a thin film made of a low refractive index material, such as MgF ₂ , SiO ₂ , CaF ₂ , MgO, Al _As a combination with a thin film made of ₂ O ₃ or the like, these may be alternately stacked, and the number of stacked layers may be 2 or more, preferably 2 to 9 layers.

  As a method for forming the multilayer thin film layer, various thin film forming methods can be used. More specifically, it is possible to control the film thickness, the film formation speed, the number of layers, or the optical film thickness (= n · d, n: refractive index, d: film thickness), etc. A physical vapor deposition method such as a chemical vapor deposition method, or a chemical vapor deposition method such as a CVD method can be used. In addition, when a thin film made of a low refractive index organic polymer is formed, a printing method such as a gravure printing method, an offset printing method, or a screen printing method, or a coating method such as a bar coating method, a gravure method, or a roll coating method is used. You can also

  In addition, when the transparent base materials 10, 20, and 30 provided with the multilayer thin film layers 11, 21, and 31 are made of an organic polymer having a low refractive index, the multilayer thin film layer laminated thereon is in contact with the transparent base material. The thin film is preferably higher than the refractive index of the transparent substrate.

  By providing a colored layer (not shown) with a colored transparent ink or the like on the multilayer thin film layer to make the color change more diverse and easy to see, the forgery prevention effect can be further improved. In addition, in the multilayer thin film layer, in order to prevent partial color change, for example, an ink obtained by dissolving a polymer material in water or an organic solvent, or mixed with an appropriate amount of pigment or dye For example, a predetermined pattern may be formed in a portion where the color change is not desired.

  Examples of the polymer material include polyvinyl alcohol, methyl cellulose, ethyl cellulose, cellulose acetate, polystyrene, polyvinyl chloride, linear saturated polyester, polymethyl methacrylate, polymethyl methacrylate, and other methacrylic resins or copolymers thereof, acrylic Resin, styrene resin, silicon resin, polyisobutyl resin and the like, or copolymers thereof.

More specifically, a black ink or colorless transparent ink containing a polymer material as described above as a vehicle and a black pigment or dye added thereto, or a material that absorbs or reflects in a portion other than the visible light region is added. On the multilayer thin film layer by printing methods such as gravure printing method, offset printing method, screen printing method, bar coating method, gravure method, roll coating method, etc. And a predetermined pattern.

  On the other hand, the light absorption layers 14 and 34 are provided in order to further emphasize the color change in the multilayer thin film layers 11 and 31. The multilayer thin film layer has a property of transmitting a specific wavelength depending on its film thickness and reflecting other wavelengths, but by absorbing the transmitted wavelength by the light absorption layers 14 and 34, the reflected wave is more clearly reflected. It is possible to make only visible. The hue of the light absorbing layers 14 and 34 is not particularly limited as long as it can absorb the wavelength of light absorbed by the multilayer thin film layers 11 and 34, but generally a dark color is used. Of the dark colors, black is generally used. Further, the light absorption layer may be provided on either the upper or lower surface of the transparent substrate as long as the above-described characteristics can be exhibited.

  In addition, the transparent retardation layers 12, 22, and 32, which cannot be normally confirmed by visual observation, are used for confirming predetermined information when observed through a separately prepared polarizing filter. It is a layer in which a phase difference is generated between the light passing through other portions. When the light reflected by the multilayer thin film layer passes through the retardation layer, it returns to the viewer as linearly polarized light, circularly or elliptically polarized light depending on the retardation value of the retardation layer. In the case of linearly polarized light, the specific light is deleted by observing the light through a linearly or circularly polarized filter, and in the case of circularly polarized light through a left or right-handed filter. A latent image corresponding to the shape of the phase difference layer can be visually recognized.

  In addition, when the multilayer thin film layer is formed on a transparent substrate exhibiting birefringence, the retardation value calculated from the retardation layer itself is actually affected by the birefringence of the transparent substrate and is not necessarily It may not be as theoretical. However, even in such a case, when viewed from the observation side, the contrast value of the latent image information visually recognized through the polarizing filter is slightly reduced because the phase difference value is different between the transparent substrate alone surface and the phase difference layer installation surface. However, it is possible to confirm the contents of the latent image with either a linear polarizing filter or a circular polarizing filter.

  Such transparent retardation layers 12, 22, and 32 for imparting retardation are formed by, for example, fixing a smectic liquid crystal or a nematic liquid crystal, and having the properties of a thermotropic liquid crystal. It can be obtained by using a liquid crystal solution containing these liquid crystals and printing them in a predetermined pattern using a gravure printing method or the like. A liquid crystal in which a functional group such as an acryl group is introduced at the terminal as the liquid crystal in the liquid crystal solution is preferably used because the physical strength is improved by crosslinking using active energy rays after the alignment of the liquid crystal is completed.

  In forming such transparent retardation layers 12, 22, and 32, an alignment film may be used in combination for the purpose of promptly aligning the liquid crystal. As a material for the alignment film, a known resin such as polyvinyl alcohol (PVA) or polyimide can be used.

  For the alignment film, a resin solution in which these resins are appropriately dissolved is used, and a thin film is applied on the multilayer thin film layer by a coating method such as wire bar, gravure, and micro gravure, and then the thin film is dried and further applied to a rubbing cloth. It may be obtained by performing a rubbing process for rubbing the thin film surface. For the rubbing cloth, known materials such as cotton and velvet can be used. By forming a thin film of a liquid crystal solution on the alignment film thus prepared, a phase difference having a more suitable phase difference can be obtained.

As the polarizing filter 20, a film made of a hydrophilic polymer represented by polyvinyl alcohol is treated with a dichroic absorber, for example, an iodine complex, and stretched, Those appropriately selected from those obtained by treating a film typified by vinyl chloride and orienting a polyene are used. In addition, the hue is not particularly limited as long as the performance of extracting polarized light is not hindered, and in addition to a gray-based material created by using iodine, a dichroic dye is used for blue, red, green, or their color. It may have a polarizing film having a mixed color.

  As the circularly polarizing filter, for example, a 4 / λ retardation film made of polycarbonate or cyclic olefin resin and bonded in a state inclined by 45 ° with respect to the linear direction of the linear polarizing film is used.

  The polarizing film of the polarizing filter may be subjected to chemical treatment for the purpose of improving water resistance and film strength as long as it does not affect the polarizing performance. Further, observation may be made using a circularly polarizing filter made using cholesteric liquid crystal.

  On the other hand, the protective layers 13, 23, 33 protect the surface of the retardation layers 12, 22, 32 from physical and chemical influences and at the same time cover them to make it more difficult to confirm the presence of the retardation layer. Provided for.

  Such protective layers 13, 23, and 33 give toughness by using a curing agent such as isocyanate and epoxy, for example, acrylic, epoxy, polyester, urethane, acrylic silicon, copolymers thereof, and resins thereof. Or a compound having a (meth) acryloyl group in the molecule, particularly those having 1 to 20 (meth) acryloyl groups.

  More specifically, active energy curable resins such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and ultraviolet rays are used. A compound that generates radicals when irradiated is preferably used.

  The formation of the protective layers 13, 23, and 33 having such a configuration can use the same technique as the formation of the adhesive layer 35 that constitutes a forgery prevention seal described later. For example, an active energy ray curable resin may be used, and a thin film provided so as to cover the retardation layer may be cured with ultraviolet rays irradiated from an ultraviolet irradiation device such as a high-pressure mercury lamp. At this time, an inert gas such as nitrogen may be filled in the ultraviolet irradiation area at the time of ultraviolet irradiation to reduce oxygen inhibition to form a stronger coating film.

  While the anti-counterfeit medium of the present invention has been described above, the anti-counterfeit seal of the present invention will be described next.

  FIG. 3 shows a schematic sectional configuration of the anti-counterfeit seal of the present invention. As is clear from the drawings, the forgery prevention seal is basically similar in structure to the forgery prevention medium shown in FIG. 1, and further includes an adhesive layer 35 as described above. It is different.

  The adhesive layer 35 is composed of, for example, vinyl chloride-vinyl acetate copolymer, polyester polyamide, acrylic, butyl rubber, natural rubber, silicone, polyisobutyl, etc. Or aggregating components such as alkyl methacrylate, vinyl ester, acrylonitrile, styrene, vinyl monomer, unsaturated carboxylic acid, hydroxy group-containing monomer, reforming component represented by acrylonitrile, polymerization initiator, plasticizer, curing agent, What added additives, such as a hardening accelerator and antioxidant, as needed can be used. The pressure-sensitive adhesive layer 35 can be formed by a known gravure printing method, offset printing method, screen printing method, or other printing method, or a bar coating method, gravure method, roll coating method, or the like. Moreover, you may provide so that it may stick together by roll lamination using the adhesive member in which both surfaces were comprised with the film separator.

  Hereinafter, preferred embodiments of the present invention will be described.

Two transparent polyethylene terephthalate (PET) resin sheets having a thickness of 25 μm are prepared as transparent base materials, and multilayer thin film layers A and B having the following constitution are respectively provided on the transparent base material side. Thus, each layer was provided by vacuum deposition.
[Configuration of multilayer thin film layer A]
High refractive index metal thin film (20 nm thick thin film made of Al) / Low refractive index thin film (thick film of 580 nm thick made of SiO)
[Configuration of multilayer thin film layer B]
High refractive index metal thin film (20 nm thick thin film made of Al) / Low refractive index thin film (thick 580 nm thin film made of SiO) / Metal reflective thin film (70 nm thick thin film made of Al).

Next, a thin film pattern was formed on each multilayer thin film layer by a gravure printing method using a liquid crystal solution having the following composition, and then dried at 50 ° C. for 3 minutes to form a retardation layer having a thickness of 0.76 μm.
[Composition of liquid crystal solution]
Liquid crystal (trade name: UCL-008, manufactured by Dainippon Ink & Chemicals, Inc.) 30 parts by weight Reaction initiator (trade name: Irgacure-184, manufactured by Ciba Specialty Chemicals)
3 parts by weight Diluent (trade name: VC-102, manufactured by Toyo Ink Manufacturing Co., Ltd.) 67 parts by weight.

Subsequently, a thin film was provided by a gravure coating method using ink having the following composition so as to cover the retardation layer, and dried at 50 ° C. for 3 minutes. The dry film thickness was 0.76 μm. Thereafter, the dried thin film was cured by irradiating with ultraviolet rays from a high-pressure mercury lamp with an irradiation energy of 500 mJ to obtain a protective layer.
[Composition of protective layer forming ink]
Acrylic monomer
40 parts by weight Reaction initiator (trade name: Irgacure 184, manufactured by Ciba Geigy) 5 parts by weight Diluting solvent (trade name: VC202C solvent, manufactured by Toyo Ink Manufacturing Co., Ltd.) 55 parts by weight.

Next, on the side of the transparent substrate on which the protective layer or the like is not laminated, a light absorption layer is laminated and provided so that the dry film thickness is 2 μm by screen printing using a black ink having the following composition: An anti-counterfeit medium of the present invention was obtained. The ink layer was dried at 100 ° C. for 1 minute.
[Composition of black ink]
Black ink (trade name: SS66 911 black, manufactured by Toyo Ink Co., Ltd.) 90 parts by weight Diluting solvent (trade name: S965 solvent, manufactured by Toyo Ink Co., Ltd.) 10 parts by weight.

After each of the two types of anti-counterfeit media obtained as described above is cut into a predetermined size, and a thin film is applied to each light absorption layer by a bar coating method using an adhesive having the following composition The thin film was dried at 80 ° C. for 1 minute to form an adhesive layer, and two types of anti-counterfeit seals were obtained. The dry film thickness was 10 μm. A release paper was bonded to the adhesive layer side.
[Adhesive composition]
Acrylic resin (trade name: BPS5160, manufactured by Toyo Ink Manufacturing Co., Ltd.) 60 parts by weight Diluting solvent (trade name: VC202C solvent, manufactured by Toyo Ink Manufacturing Co., Ltd.) 40 parts by weight.

  After sticking the obtained anti-counterfeit sticker to the gift certificate at the adhesive layer, the color copy was made as a manuscript, and the gift certificate used as a copy manuscript had various colors depending on the observation angle. However, in the copied material, these color changes were not observed in the portion corresponding to the anti-counterfeit sticker.

  In addition, when a linear polarizing filter prepared separately was placed on the anti-counterfeit seal and observed, the copy image showed the latent image part visible, and when the filter was rotated, the visualized part became darker or brighter according to the rotation. However, such a phenomenon was not confirmed in the copied material.

FIG. 5 is an explanatory diagram showing a schematic cross-sectional configuration along the line X-X ′ of the forgery prevention medium shown in FIG. 4. It is explanatory drawing which shows the general | schematic cross-section structure which concerns on other embodiment of the forgery prevention medium of this invention. It is explanatory drawing which shows the general | schematic cross-section structure of the forgery prevention seal | sticker of this invention. It is explanatory drawing which shows the planar state of the forgery prevention medium of this invention. It is explanatory drawing which shows a mode when the anti-counterfeit medium shown in FIG. 4 is observed through a polarizing filter and the information that has been formed into a latent image is visually recognized. It is a L * a * b * system chromaticity diagram which shows the condition of the color change in a multilayer thin film layer when changing a visual angle and observing the forgery prevention medium which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anti-counterfeit medium 10, 20, 30 Transparent base material 11, 21, 31 Multilayer thin film layer 12, 22, 32 Retardation layer 13, 23, 33 Protective layer 14, 34 Light absorption layer 35 Adhesion layer 50 Deflection filter

Claims (6)

  Having a multilayer thin film layer formed by laminating a plurality of thin films having different optical properties, such as a ceramic thin film, a metal thin film, and a transparent resin thin film, on at least one of the multilayer thin film layer and the transparent substrate; An anti-counterfeit medium characterized by having a transparent retardation layer in the part.   2. The medium for preventing forgery according to claim 1, wherein the transparent retardation layer is formed by fixing a nematic or smectic liquid crystal.   The anti-counterfeit medium according to claim 1, further comprising a light absorption layer below the retardation layer.   The forgery prevention medium according to any one of claims 1 to 3, wherein the multilayer thin film layer is provided on at least a part of the transparent substrate.   The forgery prevention medium according to claim 1, wherein a protective layer is provided so as to cover the retardation layer.   An anti-counterfeit seal comprising an adhesive layer on one surface of the anti-counterfeit medium according to claim 1.