JP2013068701A - Forgery preventive medium, method for determining genuineness thereof, and method for producing forgery preventive medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forgery preventive medium more difficult to forge and easy to discriminate visually whether the medium is forged one or not, even in the forgery preventive medium using a polarized light latent image.SOLUTION: A forgery preventive medium 10 is composed by laminating, on a base material 11, a forming layer 12 having an irregular structure on a surface, a reflection layer 13, orientation control layers 21, 22 for orienting liquid crystals, a liquid crystal layer 14 having a portion different in a thickness by burying the irregularities and oriented along a prescribed direction by an effect of the orientation control layers 21, 22, and a protection layer 15 in this order.

Description

  The present invention relates to a structure of an anti-counterfeit medium that reveals a latent image such as a hidden character or a hidden pattern by using a polarizing filter, an authenticity determination method for determining the authenticity of an anti-counterfeit medium, and a manufacturing method of an anti-counterfeit medium.

  Conventionally, securities and authentication media such as banknotes, gift certificates, and passports have been made by pasting some medium that is difficult to forge (hereinafter referred to as an anti-counterfeit medium) as an anti-counterfeiting measure. There, the authenticity of the authentication medium is determined by the presence / absence of the anti-counterfeit medium or the authenticity determination of the anti-counterfeit medium itself by visual inspection or using a verifier.

  However, an anti-counterfeit medium that can determine authenticity by simple visual inspection is easily forged. Therefore, in recent years, a technique for forming a latent image that can be seen only with polarized light, which is more difficult to forge, in advance in a medium and revealing the latent image in combination with a polarizing plate has been disclosed as a forgery prevention technique. In this method, a monotone latent image appears by superimposing a simple flat polarizing plate on a medium, and authenticity determination is performed based on whether the latent image is visible or not (see, for example, Patent Document 1).

JP 2008-183832 A

  The anti-counterfeit medium using the above polarized latent image has a problem that since it is monotone, it has a weak power to appeal to the eye during verification, and cannot be distinguished from counterfeit at a glance. Moreover, even if it is difficult, it does not necessarily mean that it cannot be imitated or counterfeited.

  Therefore, the present invention provides an anti-counterfeit medium that is a forgery-preventing medium using a polarization latent image, but is more difficult to forge and is visually easy to determine whether it is a forged medium. Objective.

  As means for solving the above-mentioned problems, the invention according to claim 1 embeds a concavo-convex structure on a base material, a formation layer having a concavo-convex structure, a reflective layer, an alignment control unit for aligning liquid crystals, and the like. The anti-counterfeit medium is characterized in that the liquid crystal layer and the protective layer, which have different thicknesses and have a portion oriented in a predetermined direction by the effect of the orientation control unit, are laminated in this order.

  The invention according to claim 2 is the anti-counterfeit medium according to claim 1, wherein the orientation control unit has a plurality of orientation directions.

  The invention according to claim 3 is characterized in that the orientation control part is a plurality of grooves formed on the surface of the formation layer exhibiting an uneven state. It is a medium.

  According to a fourth aspect of the present invention, in the first to third aspects, the alignment control unit is an alignment film formed on the surface of the formation layer with a material different from the formation layer. The anti-counterfeit medium according to any one of the above items.

  The invention according to claim 5 is the anti-counterfeit medium according to any one of claims 1 to 4, wherein an adhesive layer is provided on the back surface of the base material.

  The invention according to claim 6 is characterized in that the anti-counterfeit medium according to claim 3 is manufactured by simultaneously forming the uneven state of the forming layer and a plurality of grooves on the surface of the forming layer. It is a manufacturing method.

  In the invention according to claim 7, whether or not a predetermined colored latent image appears by observing the anti-counterfeit medium via the polarizing plate and changing the observation angle of the anti-counterfeit medium. Is a method for determining the authenticity of an anti-counterfeit medium, wherein the authenticity of the anti-counterfeit medium is determined visually or by reading with a machine.

  The anti-counterfeit medium according to the present invention has a special visual effect that the polarized latent image that appears when the polarizing plates are superimposed is colored in multiple colors, and different colored images can be observed by changing the observation angle. ing. Since the visualized colored image has a stronger appeal for vision than mono-color display and can be easily discriminated, it has the effect of exhibiting high forgery discrimination power.

  In addition, in order to color the polarization latent image, it is necessary to have advanced processing technology that secures multiple narrow spaces to accommodate the liquid crystal and imparts orientation to the wall surface, imitating such an environment surrounding the liquid crystal. Thus, it is extremely difficult to achieve the same visual effect as the genuine product compared to imitating the monotone type.

  In addition, the forgery prevention medium having a configuration having an adhesive layer on the back surface can be easily attached to a medium to be pasted such as paper.

  Further, if the macroscopic unevenness for changing the thickness of the liquid crystal and the fine groove for controlling the alignment of the liquid crystal are formed at the same time, the process can be rationalized and the anti-counterfeit medium having the above characteristics can be manufactured at low cost.

It is a top view which shows roughly the forgery prevention medium which concerns on 1st Embodiment of this invention. FIG. 2 is a cross-sectional view taken along the line AA of the forgery prevention medium illustrated in FIG. 1. It is a schematic diagram which shows roughly the orientation control layer of the forgery prevention medium shown in FIG. It is a schematic diagram which shows schematically the preparation methods of the formation layer of the forgery prevention medium shown in FIG. It is a schematic diagram which shows schematically the formation layer obtained by FIG. FIG. 2 is a plan view showing an example observed through a polarizing plate using the anti-counterfeit medium having the configuration of FIG. 1. FIG. 6B is a plan view showing an example in which the anti-counterfeit medium is observed by rotating the polarizing plate by 45 ° from FIG. 6A. FIG. 6B is a perspective view showing an example of a polarization latent image that appears when the forgery prevention medium observation direction is tilted by an angle −θ from the Z direction in a plane perpendicular to the X direction from FIG. 6A.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same referential mark is attached | subjected to the component which exhibits the same or similar function through all the drawings, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a plan view schematically showing a first configuration of an anti-counterfeit medium according to the present invention. FIG. 2 is a cross-sectional view of the forgery prevention medium 10 shown in FIG.

  The anti-counterfeit medium 10 includes a base material 11, a forming layer 12, a reflective layer 13, a liquid crystal layer 14, and a protective layer 15. The front surface of the anti-counterfeit medium 10 is a surface on the protective layer 15 side when viewed from the base material 11.

(Base material)
The substrate 11 is a film or sheet made of a resin such as a polyethylene terephthalate (hereinafter referred to as “PET”) film. The substrate 11 may or may not have light transmittance. Moreover, the base material 11 may have a single layer structure, and may have a multilayer structure. Furthermore, the substrate 11 may be subjected to processing such as antistatic processing, mat processing, embossing processing, or the like, as long as it does not affect the image recognition of the polarization latent image.

(Formation layer)
The formation layer 12 is a layer for controlling the orientation and film thickness of the liquid crystal layer 14, and FIG. 4 is a schematic view schematically showing a method for forming the formation layer 12. The embossed original plate 41 has film thickness control regions 2A, 2B, etc. having different depths in one plane.

  The forming layer 12 is, for example, a thermoplastic resin layer, and is obtained by a method of pressing an original plate provided with a plurality of convex portions while applying heat, that is, a heat embossing method. Alternatively, the forming layer 12 is, for example, an ultraviolet curable resin, and is formed by a method in which the ultraviolet curable resin is cured by irradiating ultraviolet rays from the back side of the resin base material while pressing the original on the original, and then the original is removed. Is also possible.

(Reflective layer)
The reflective layer 13 covers the entire front side of the formation layer 12. The reflective layer 13 may cover only a part of the front surface of the forming layer 12. Alternatively, the reflective layer 13 may at least partially cover the back surface of the forming layer 12. In this case, the formation layer 12 is light transmissive at least at a part of the position corresponding to the reflection layer 13. In this case, typically, the formation layer 12 is transparent at least at a part of the position corresponding to the reflection layer 13.

  The reflective layer 13 may have a light scattering property or may not have a light scattering property. The reflective layer 13 may have a single layer structure or a multilayer structure.

  As a method of providing the reflective layer 13, an ink having a light reflecting effect may be provided by a known printing method, or a metal may be provided as the reflective layer 13 by a method such as vapor deposition or sputtering. Examples of the metal used for the reflective layer 13 include metals such as Al, Sn, Cr, Ni, Cu, Au, Inconel, stainless steel, and duralumin. Further, the present invention can be realized by preparing a transfer foil having an ink layer having a light reflection effect on the entire surface or in a pattern by a printing method, or preparing a transfer foil having a metal reflective layer. The reflective layer 13 may be provided by transferring to the forming layer 12 used in the above, or a reflective layer may be provided by laminating a film having a metal foil or a metal layer.

  When patterning the metal reflective layer, after forming the metal reflective layer on the entire surface of the base material, it may be patterned by a known method such as etching, laser processing, washing sea light processing, etc. The converted metal reflection layer may be transferred or laminated. Further, a diffractive structure forming layer having a diffractive structure may be provided instead of the non-periodic metal reflective layer. By forming the diffractive structure, the decorative effect and the forgery prevention effect are improved.

(Orientation control layer)
The alignment control layers 21 and 22 shown in FIG. 2 are used for aligning liquid crystals. As a method of forming the alignment control layers 21 and 22, a known technique can be used. For example, a method of performing an alignment process by rubbing or vacuum oblique deposition, or a method of forming a groove for controlling the alignment. For example, a method of aligning using a photo-alignment film using a photoreaction by linearly polarized light or oblique non-polarized light irradiation can be employed.

  FIG. 3 shows the alignment directions of the alignment control layers 21 and 22. The alignment control layers 21 and 22 each have an effect of controlling the alignment of the liquid crystal in the direction in which the stripe extends. The orientation direction differs by 45 degrees on the left and right in the figure.

  FIG. 4 is a schematic view schematically showing a method for forming the formation layer 12. The embossing original plate 41 has film thickness control areas 2A and 2B for controlling the film thickness of the liquid crystal in one plane. The film thickness control regions 2A and 2B have steps (unevenness) with different depths. In the lower part of FIG. 4, the formation layer 12 and the reflection layer 13 are laminated on the front surface side of the substrate 11, and the orientation control layers 21 and 22 are further formed thereon. Using this embossed original plate 41, the laminate is embossed after alignment.

  FIG. 5 is a schematic view schematically showing the formation layer 12 having the film thickness control regions 2A and 2B for controlling the film thickness and the orientation control layers 21 and 22. As shown in FIG. According to the above method, a plurality of regions having different depths and widths for controlling the film thickness of the liquid crystal can be formed in one plane. Also, according to these methods, predetermined liquid crystal orientation can be imparted to the region even if it is complex or plural. It can also be set as the orientation control layer which does not have orientation control ability. In this case, the liquid crystal becomes a non-oriented optically isotropic layer at the site.

(Liquid crystal layer)
The liquid crystal layer 14 is formed by solidifying a liquid crystal material. Typically, the liquid crystal layer 14 is a polymer birefringent layer formed by curing a polymerizable liquid crystal material having fluidity with ultraviolet rays or heat.

  As shown in FIG. 2, the liquid crystal layer 14 includes a plurality of liquid crystal parts 141 and 142 having different alignment states and a plurality of liquid crystal parts 14A and 14B having different film thicknesses. A plurality of liquid crystal regions 141 and 142 having different alignment states correspond to the alignment control layers 21 and 22, respectively. A plurality of liquid crystal regions 14A, 14B, and 14C having different film thicknesses correspond to the film thickness control regions 2A and 2B, respectively.

(Protective layer)
The protective layer 15 covers the front surface of the liquid crystal layer 14. The protective layer 15 is a light-transmitting layer having light transmittance, and is typically transparent, but may be colorless and transparent, may be colored and transparent, at least optically, etc. It needs to be anisotropic.

  The protective layer 15 serves as a protective layer that suppresses the deterioration of the image displayed by the anti-counterfeit medium 10 so that the liquid crystal layer 14 or the like is not easily damaged or photodegraded. The protective layer 15 may have a single layer structure or a multilayer structure.

  The protective layer 15 is made of, for example, a resin, and examples of the material include thermoplastic resins such as acrylic resin, urethane resin, vinyl chloride resin-vinyl acetate copolymer resin, polyester resin, melamine resin, epoxy resin, polystyrene resin, and polyimide resin. Resins, thermosetting resins, or ultraviolet or electron beam curable resins can be used alone or in combination. The protective layer 15 can be omitted.

  Next, a mode of observing a polarization latent image using the anti-counterfeit medium 10 of the present invention and an authenticity determination method for verifying that an article including the anti-counterfeit medium 10 is genuine will be described.

  FIG. 1 is a plan view schematically showing a forgery prevention medium 10. When visually observing without holding the polarizing plate 50, the latent image display area indicated by a dotted line cannot be distinguished from other areas, and all the areas look the same.

  6A and 6B are examples showing a polarization latent image when the polarizing plate 50 is held over the anti-counterfeit medium 10 of the present invention. The arrow indicates the optical axis direction of the polarizing plate 50.

  In FIG. 6A, the display units 101 and 102 can transmit polarized light through the polarizing plate 50 and have different colors in each region because the optical axis of the polarizing plate 50 and the optical axis of the retardation layer made of liquid crystal are parallel. The latent image is displayed brightly. In addition, in the display units 201 and 202, since the angle of the optical axis of the polarizing plate 50 and the optical axis of the liquid crystal layer 14 intersect at 45 °, the polarized light passing through the polarizing plate 50 is rotated by 90 ° by the retardation layer. Is shielded from light and displayed dark. In the display portion 301, no change occurs because there is no liquid crystal region.

  6B is a plan view showing how the anti-counterfeit medium 10 looks when the polarizing plate is rotated 45 ° from the state of FIG. 6A. In these cases, the display units 101 and 102 are dark on the same principle as described above, and the display units 201 and 202 display the latent images of different colors brightly in the respective regions.

  In this way, the anti-counterfeit medium 10 is observed through the polarizing plate 50, and it is confirmed that the polarization latent image is a latent image pattern having a predetermined coloring state. It can be confirmed that If the medium is an anti-counterfeit medium showing the same polarization latent image, it is possible to determine whether the article provided with the medium is genuine.

  These authenticity determinations may be performed using a machine.

  Here, the reason why each color appears different when the display unit 101, the display unit 201, the display unit 102, and the display unit 202 are observed will be described with reference to mathematical expressions.

  The retardation Re of the liquid crystal layer 14 depends on the film thickness d of the liquid crystal layer 14 and its birefringence Δn, as shown in the following equation (1).

Re = Δn × d (1)
Here, a _{Δn = n e -n o, n} e, n o are each extraordinary light refractive index for ordinary light.

A pair of linearly polarizing films face each other so that their transmission axes are perpendicular to each other, and a liquid crystal layer 14 is interposed between them so that the optical axis forms an angle θ with respect to one transmission axis of the linearly polarizing film. When one linearly polarizing film is illuminated with light having a wavelength λ from its normal direction, the intensity of light incident on the liquid crystal layer 14 is I _0, and the intensity of light passing through the other linearly polarizing film is I. The intensity I can be expressed by the following equation (2).

I = I ₀ × sin ² (2θ) × sin ² (Re × π / λ) (2)
As is apparent from equation (2), the wavelength λ at which the intensity I of the transmitted light is maximum depends on the retardation Re. As shown in equation (1), the retardation Re depends on the film thickness d of the liquid crystal layer 14 and its birefringence Δn. That is, the wavelength λ at which the transmitted light intensity I is maximum depends on the film thickness d of the liquid crystal layer 14. Therefore, the spectrum of transmitted light has a different profile from the spectrum of incident light.

  Thus, when the liquid crystal layer 14 is sandwiched between a pair of linearly polarizing films, transmitted light having a spectrum profile different from that of incident light can be obtained. Similarly, when the liquid crystal layer 14 is sandwiched between the linearly polarizing film and the reflective layer 13, reflected light having a spectrum profile different from that of the incident light can be obtained. Therefore, when the display units 101, 201, 102, and 202 are observed, the thickness and the orientation direction are different, so that the colors appear different.

  When the anti-counterfeit medium 10 is applied to the printed matter, the anti-counterfeit medium 10 may be inserted into paper in a form called a thread (also referred to as a strip, a filament, a thread, a safety band, or the like).

  When an adhesive is used in the anti-counterfeit label or printed matter, a general material can be used as the material of the adhesive.

  For example, an adhesive such as vinyl chloride-vinyl acetate copolymer, polyester polyamide, acrylic, butyl rubber, natural rubber, silicon, or polyisobutyl can be used alone. Or these pressure sensitive adhesives include coagulation components such as alkyl methacrylates, vinyl esters, acrylonitrile, styrene, vinyl monomers, modifying components such as unsaturated carboxylic acids, hydroxy group-containing monomers, acrylonitrile, polymerization initiators, plastics What added additives, such as an agent, a hardening | curing agent, a hardening accelerator, antioxidant, as needed can be used.

  As a method for forming the adhesive layer, a known gravure printing method, an offset printing method, a screen printing method or the like printing method or a bar coating method, a gravure method, a roll coating method or the like can be used.

  Furthermore, what formed the said adhesive in the separator previously may be prepared, a separator may be peeled off and bonded together to a forgery prevention medium.

  Further, in order to facilitate the handling of the anti-counterfeit medium subjected to the adhesive processing, a release paper or a release film subjected to a release treatment may be installed on the adhesive layer.

  The anti-counterfeit medium 10 of the present invention is not only used as a medium as a means for counterfeiting or duplication, but may be used as, for example, an electro-optical liquid crystal cell that performs optical and alignment functions.

  Hereinafter, specific examples of the anti-counterfeit medium 10 of the present invention will be described with reference to FIGS.

  A polyethylene terephthalate film subjected to a release treatment was prepared as the base material 11, and a forming layer 12 was formed by applying a urethane resin by microgravure at a coating thickness of 8 μm and a drying temperature of 110 ° C.

  Next, an aluminum thin film layer having a thickness of 50 nm was provided on the entire surface of the formation layer 12 using a vacuum deposition method as the reflection layer 13.

Next, an alignment film ink solution was applied to the entire surface by a bar coater method. The composition of the applied alignment film ink is shown below.

Polyvinyl alcohol resin (trade name: PVA-117, Kuraray Co., Ltd.) 10% by weight
90% by weight of solvent (water)
This coating film was formed so that the dry film thickness was 2 μm.

Next, using a rubbing cloth (FINE PUFF YA-20-R manufactured by Yoshikawa Chemical Co., Ltd.), the coating film was covered with one side and the other was rubbed twice. As a result, two alignment control regions (alignment control layers 21 and 22) having different alignment directions as shown in FIG. 3 were obtained.

  Next, an embossing original plate 41 having film thickness control regions 2A and 2B having different depths of unevenness as schematically shown in the upper part of FIG. 4 was prepared. The depths of the film thickness control regions 2A and 2B were 3 μm and 5 μm, respectively.

Next, the embossed original plate 41 is used to thermally emboss the formation layer at 220 ° C. and a pressure of 10 kgf / cm ² , and the formation layer 12 has an uneven region (film) for film thickness control as shown in FIG. Thickness control areas 2A, 2B) were transferred and formed.

  Thereafter, UV curable liquid crystal UCL-008 manufactured by Dainippon Ink & Chemicals, Inc. was coated on the formation layer by microgravure, and then cured by irradiating non-polarized ultraviolet rays.

  Next, an acrylic resin was formed as the protective layer 15 by microgravure at a coating thickness of 1 μm and a drying temperature of 100 ° C.

  Next, the anti-counterfeit medium 10 using the polarizing plate 50 was observed to check whether a desired image appeared.

  FIG. 6A is a plan view showing an example in which the created anti-counterfeit medium 10 is observed through the polarizing plate 50. Since the display units 101 and 102 have the optical axis of the polarizing plate 50 and the angle of the optical axis of the retardation layer parallel to each other, the polarized light passing through the polarizing plate 50 can be transmitted, and a latent image of a different color is displayed brightly in each region. Is done. In addition, in the display units 201 and 202, since the angle of the optical axis of the polarizing plate 50 and the optical axis of the liquid crystal layer 14 intersect at 45 °, the polarized light passing through the polarizing plate 50 is rotated by 90 ° by the retardation layer. Is shielded from light and displayed dark. In the display portion 301, no change occurs because there is no liquid crystal region.

  Next, FIG. 6B is a plan view showing an example of observing the anti-counterfeit medium 10 when the polarizing plate 50 is rotated by 45 ° from FIG. 6A. In these cases, the display units 101 and 102 are dark on the same principle as described above, and the display units 201 and 202 display the latent images of different colors brightly in the respective areas.

  Next, FIG. 6C is a perspective view showing an example of a polarization latent image that appears when the observation direction is tilted by an angle −θ from the Z direction in a plane perpendicular to the X direction from FIG. 6A. The display units 101 and 102 display latent images of different colors in the respective areas, the latent image display areas are displayed brightly, and the display units 201 and 202 are displayed darkly based on the same principle as described above. Moreover, since the distance which permeate | transmits the liquid-crystal layer 14 changes compared with the thing from the front, it observed with the color different from the front, and the effect assumed was acquired.

  In this way, by changing the angle of the polarizing plate 50 and the observation angle through the polarizing plate 50, the light and darkness of the polarization latent image is reversed, and the authenticity can be determined by changing the color.

  The anti-counterfeit medium, the anti-counterfeit label, the printed matter, and the transfer foil of the present invention can be used for the above-mentioned article as a counter measure against forgery in securities such as banknotes, gift certificates, passports, and various authentication media. Further, the authenticity determination method for an anti-counterfeit medium of the present invention makes it possible to determine the authenticity of an article as described above.

  DESCRIPTION OF SYMBOLS 10 ... Anti-counterfeit medium, 11 ... Base material, 12 ... Formation layer, 13 ... Reflection layer, 14 ... Liquid crystal layer, 14A, 14B ... Liquid crystal part with different film thickness, 141, 142 ... Liquid crystal part with different orientation, 15 ... Protection Layer, 21, 22 ... orientation control layer, 41 ... embossed original plate, 50, polarizing plate, 101, 102, 201, 202, 301 ... display unit, 2A, 2B ... film thickness control region.

Claims (7)

  On the base material, a formation layer having a concavo-convex structure, a reflective layer, an alignment control unit for aligning liquid crystals, a thickness that varies by embedding the concavo-convex portions, and a portion that is aligned in a predetermined direction by the effect of the alignment control unit An anti-counterfeit medium characterized in that a liquid crystal layer and a protective layer are laminated in this order.   The forgery prevention medium according to claim 1, wherein the orientation control unit has a plurality of orientation directions.   The forgery prevention medium according to claim 1, wherein the orientation control unit is a plurality of grooves formed on a surface of the formation layer exhibiting an uneven state.   The forgery prevention medium according to any one of claims 1 to 3, wherein the orientation control unit is an orientation film formed on a surface of the formation layer with a material different from the formation layer.   The forgery prevention medium according to any one of claims 1 to 4, wherein an adhesive layer is provided on a back surface of the base material.   The method for producing an anti-counterfeit medium according to claim 3, wherein the uneven state of the formation layer and a plurality of grooves on the surface of the formation layer are simultaneously formed.   With respect to the anti-counterfeit medium, the anti-counterfeit medium is observed by visual or mechanical reading as to whether a predetermined colored latent image appears by observing the anti-counterfeit medium via a polarizing plate and changing the observation angle. A method for determining the authenticity of an anti-counterfeit medium, wherein the authenticity of the medium is determined.

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