JP5609033B2 - Anti-counterfeit media - Google Patents

Description

  The present invention is used by being embedded in or pasted on an article that can easily identify counterfeit products of securities such as stock certificates, bonds, checks, lotteries, and gift certificates manufactured using a color copying machine. The present invention relates to the structure of a forgery prevention medium.

  In recent years, copying machines using electrophotographic technology have become widespread, and anyone can easily copy characters and images printed on paper using this. In particular, using a recent color digital copying machine, it has become possible to easily produce even a copy that is extremely difficult to distinguish between an original document and a copy.

The principle of a general color digital copying machine is to irradiate a document with light and detect reflected light with a CCD line sensor. In the CCD line sensor, a digital signal corresponding to the intensity of the reflected light is generated and transmitted to a memory in the copying machine. This reading process is performed for three colors of red (R), green (G), and blue (B), and the digital signal in each case is stored in the memory.
Next, based on the stored digital signal, the surface of the photosensitive drum is irradiated with laser light, and yellow (Y), magenta (M), cyan (C), and black (Bk) toners are applied to the photosensitive drum. The toner is electrostatically adsorbed upward, and these toners are sequentially transferred and fixed on a sheet such as paper. Thereby, an elaborate copy on which a color image is formed can be obtained.

  While such color copying is convenient, securities such as stock certificates, bonds, promissory notes, checks, and printed matter such as admission tickets and boarding passes are easily forged. For this reason, various proposals have been made to take anti-duplication measures on printed matter so that counterfeit products cannot be easily manufactured by copying.

  For example, a technique has been proposed in which the color of a color copy is different from the color of an original. In other words, if a securities that can be used as a manuscript is colored with a very pale color, the copy will not be able to accurately reproduce the pale color part. Also, a halftone dot with a different size will be formed on the manuscript. Even if the reproducibility of small halftone dots deteriorates, the color reproducibility of copies is reduced by printing green, purple, orange, gold, silver, etc., which are colors not found in color copier toner. In addition, it is the same color by using two types of inks characterized in the region where human visibility is low, for example, wavelength regions around 380 nm to 450 nm and 650 to 780 nm. Some reproductions are reproduced in different colors.

  However, in a color copying machine, it is possible to correct the color to be output by changing the digital data separated into three colors and stored in the memory. Further, digital presses that can correct digital data read by a color scanner using a principle similar to that of a color copying machine and output the data by a color printer or color copying machine are becoming widespread. Therefore, it is possible to precisely reproduce the color of the document with some effort, and it is difficult to completely prevent forgery with the above-described technique.

In addition, for example, a technique has been proposed in which a special part that cannot be reproduced by a color copying machine is provided in securities. Among these, a technique of providing an OVD (Optical Variable Device) foil (refer to Patent Documents 1 and 2) such as a hologram foil on the surface of securities or the like has already been put into practical use. According to this, since the light on the silver surface of the hologram is specularly reflected, the reflected light is not incident on the CCD line sensor, and the portion that was the silver surface in the original is reproduced in black on the copy, or the refractive index. When the ceramics with different thicknesses are laminated in a plurality of layers having an appropriate film thickness, a special optical thin film whose color changes depending on the viewing angle is formed (see Patent Document 3), and such a property cannot be obtained with a copy. Proposals have also been made of a method that can easily determine authenticity, and a method in which a thin film formed by this method is finely crushed and fragments are mixed with ink for printing.

  However, because of the development of embossing technology for holograms, the formation of reflective layers using relief-type diffracted light has become more difficult than before, and multilayer thin film has begun to be sold as a general packaging film. It can be easily copied or obtained.

  In addition, a technique has been disclosed in which ink that is printed on a form such as a guarantee is made fluorescent and has alteration resistance (see Patent Document 4). This technique can prevent counterfeiting in copiers, but fluorescent ink is now a material that is commonly used in general printed materials for advertising purposes. If a counterfeiter detects the presence of fluorescent ink in a counterfeit object, In addition, it is easy to duplicate the fluorescent ink including the incorporation of the fluorescent ink in the same manner as the genuine product.

JP-A-6-259013 Japanese Patent Laid-Open No. 7-089293 JP-T-2004-505158 Japanese Patent Publication No.59-3278

  The present invention has been made in view of the above situation, and it is an object of the present invention to provide a structure of an anti-counterfeit medium that is difficult to forge by copying.

A first invention for solving the above-described problems includes a fluorescent light-emitting layer that emits visible light by irradiating ultraviolet rays on one surface of a base material, and a retardation layer formed by fixing liquid crystal. The medium is laminated in this order, and is a forgery prevention medium characterized by having no reflective layer .

  A second aspect of the present invention is a forgery comprising a retardation layer formed by fixing a liquid crystal in which a phosphor that emits visible light by irradiating at least ultraviolet rays is fixed on one surface of a substrate. This is a prevention medium.

  A third invention is the anti-counterfeit medium according to claim 1 or 2, wherein the liquid crystal is a nematic liquid crystal or a smectic liquid crystal.

  4th invention formed the orientation layer for controlling the orientation of the said liquid crystal between the said base material and retardation layer, The any one of Claims 1-3 characterized by the above-mentioned. This is a medium for preventing forgery.

  According to a fifth aspect of the present invention, there is provided the anti-counterfeit medium according to any one of claims 1 to 4, wherein the other surface of the base material is subjected to adhesive processing.

The printed matter provided with the anti-counterfeit medium according to the present invention is difficult to counterfeit even if a copying machine such as a digital press apparatus capable of adjusting the print pattern in software is used. Further, it can be easily determined that copying has been performed by a copying machine such as a color copying machine. Further, it is difficult to externally combine a copy, a phosphor layer, a hologram layer, and the like into a counterfeit product.

  In addition, the second invention in the present invention is a forgery prevention capable of forming a high-definition image that cannot be achieved by cutting and pasting a retardation film by using a printing technique with a material that gives different visibility through a filter. It is a medium.

FIG. 1 is a plan view showing an embodiment of a thermal transfer sheet according to the present invention.
2 is a cross-sectional view taken along line YY ′ in FIG.
FIG. 3 is a theory Akirazu that shows the appearance of the latent image.
FIG. 4 is an explanatory diagram showing a configuration of a transfer retardation layer .

  Hereinafter, embodiments of the present invention will be described.

Figure 1 is a diagram of a top view showing an embodiment of the anti-counterfeit medium according to the present invention, FIG. 2 in Y 1 - is a view of a cross section in the Y 'line. FIG. 3 is a view of the anti-counterfeit medium shown in FIG. 1 when viewed through a linear polarization filter while irradiating ultraviolet rays using black light. The anti-counterfeit medium 10 shown in FIG. 1 is not visible when viewed under natural light.

  As shown in FIG. 2, in the present invention, the adhesive layer 5 is formed on one side of the base material 1, and the fluorescent light emitting layer 2 and the adhesive layer are formed on the base material 1 opposite to the adhesive layer forming surface. 3 and the retardation layer 4 are sequentially laminated.

  When the anti-counterfeit medium 10 of FIG. 1 is viewed using the linearly polarizing filter 11 while irradiating ultraviolet rays with the black light 12, a bright image portion and a dark image portion in the vicinity thereof are emitted by fluorescence as shown in FIG. appear. In addition, a retardation layer is disposed so that the brightness of an image is reversed when the linear polarizing filter is rotated by 45 °.

  FIG. 4 is a diagram showing an example of a specific layer structure for producing the retardation layer of the forgery prevention medium 10 of FIG. After the alignment film 6 is formed on the substrate and subjected to alignment treatment such as rubbing, the retardation layer 4 made of nematic liquid crystal is formed. Next, the heat-sensitive adhesive layer 3 is formed on the retardation layer 4, and then the retardation layer 4 and the fluorescent light-emitting layer 2 are bonded to each other while pressing and heating on the fluorescent light-emitting layer. A medium for preventing forgery is formed by peeling off.

  In addition to the above configuration, a reflective layer made of metal or the like may be provided between the fluorescent light emitting layer 2 formed on the base material 1 of the anti-counterfeit medium and the base material 1. Further, the retardation layer and the fluorescent light emitting layer may have a desired shape, and for example, shapes such as figures and letters can be raised.

  Furthermore, a protective layer may be provided on the uppermost layer for the purpose of protecting the anti-counterfeit medium from ultraviolet rays and physical impact, and if the cut is made in the base material and the seal is peeled off, it may be broken from the cut in the base material. It is also possible to make the structure not peeled off.

  Below, the structure of the forgery prevention medium of this invention is demonstrated in detail.

Here, the liquid crystal for imparting a phase difference to the retardation layer is a smectic liquid crystal or a nematic liquid crystal, and has the properties of a thermotropic liquid crystal. These liquid crystals may be uniformly coated on a substrate using a gravure printing method or the like, or may be pattern printed so as to have a predetermined pattern. In that case, you may dilute using a solvent etc. as needed. In addition, it is more preferable that a functional group such as an acrylic group is introduced at the end of the liquid crystal when the alignment of the liquid crystal is completed and then crosslinking is performed using an active energy ray to improve the physical strength. The retardation value of the retardation layer formed from the liquid crystal is set to be an integral multiple of (1/2) λ.

  An alignment film may be used for the purpose of quickly aligning the liquid crystal. As a material for the alignment film, a known resin such as polyvinyl alcohol (PVA) or polyimide can be used. A resin solution in which these resins are appropriately dissolved is applied onto a substrate using a coating method such as a wire bar, gravure, or microgravure, and then dried. Thereafter, a rubbing process is performed by rubbing the alignment film surface with a rubbing cloth to obtain an alignment film. As the rubbing cloth, known materials such as cotton and velvet can be used.

  A more suitable phase difference can be obtained by coating liquid crystal on the alignment film thus prepared.

  The retardation layer made of liquid crystal may be directly formed on the anti-counterfeit medium, but may be separately formed on another substrate and then transferred to the anti-counterfeit medium.

  The base material is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, polystyrene synthetic resin film, natural resin film, Synthetic paper, paper, glass plates, etc. can be used alone or in combination with a composite. The thickness may be appropriately selected according to the purpose of use of the forgery prevention medium.

  In addition, as a base material for phase difference layer formation in the case of producing a forgery prevention medium and a phase difference layer separately, said synthetic resin film or a natural resin film is suitable.

The material used for the light reflection layer is not particularly limited as long as light reflectivity is obtained, and examples thereof include metals such as aluminum, gold, silver, and copper. These materials can be used singly or in layers, and are formed on a substrate with a thickness of 50 to 1000 mm using a known method such as vacuum deposition or sputtering.
Moreover, you may color the hue which is different from the colored layer of the phase difference layer which consists of liquid crystals on a light reflection layer.

  As the phosphor used for the fluorescent light emitting layer, generally known inorganic and organic phosphors can be used as appropriate. For example, examples of the inorganic fluorescent material include a zinc sulfide-copper mixture, a zinc oxide-zinc mixture, a cadmium sulfide-copper mixture, and the like. Examples of the organic fluorescent agent include thioflavine, fluorescein, and Balifast Red 1308 in which rhodamine 6G is oil-solubilized.

  A known gravure printing method or offset is applied to the substrate by dispersing or dissolving these materials together with an organic solvent in a resin such as polyvinyl acetate, polyvinyl chloride, polyvinyl butyral, polyvinyl alcohol, polyamide, polyamideimide, polyester, or acrylic. It is produced by applying and drying using a printing method such as a 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.

  In the anti-counterfeit medium according to the present invention, the surface opposite to the surface on which the retardation layer is provided may be subjected to adhesion and adhesion processing. Common materials can be used as adhesive goods, such as vinyl chloride-vinyl acetate copolymer, polyester polyamide, acrylic, butyl rubber, natural rubber, silicon, polyisobutyl, etc. Or, an aggregating component such as alkyl methacrylate, vinyl ester, acrylonitrile, styrene, vinyl monomer, a modifying component represented by unsaturated carboxylic acid, hydroxy group-containing monomer, acrylonitrile, polymerization initiator, plasticizer, curing agent In addition, those added with additives such as curing accelerators and antioxidants as necessary can be used. For the formation of the adhesive layer, a known gravure printing method, offset printing method, screen printing method or other printing method or bar coating method, gravure method, roll coating method or other coating method can be used.

Further, a material in which an adhesive is previously formed on a separator may be prepared, and the separator may be peeled off and bonded to an anti-counterfeit medium. Further, in order to facilitate the handling of the anti-counterfeit medium subjected to the adhesive processing, a release treatment was appropriately performed. A release paper or a release film may be placed on the adhesive layer. These materials can be used for the adhesive layer as appropriate.

The polarizing plate may be a polymer polycrystalline type such as a PVA-iodine type in which iodine is absorbed in a PVA stretched film, a dichroic dye type, a metal or metal compound-containing type, a polyene type, and in particular, a PVA-iodine type, A dichroic dye type film is used. Polarizing film is preferably used alone those bonded a film made of triacetyl cellulose (TAC) reinforcing the top and bottom of the film for physical strength is low as a polarizing plate.

  In addition, in order to perform fluorescence emission using ultraviolet rays, it is necessary to use a TAC film that does not contain an ultraviolet absorber.

  The present invention will be described in detail with reference to specific examples.

<Example 1>
[Transfer phase layer]
An alignment film solution in which an alignment film resin was dissolved in a solvent was applied to a 25 μm-thick polyethylene terephthalate (deposition PET) on the entire surface using a bar coater method, and dried at 100 ° C. for 2 minutes. The film thickness at this time was 3 μm. Thereafter, a rubbing cloth was used to perform rubbing treatment in a pattern so that the image forming portion and its peripheral portion had an angle of 45 ° on the front surface of the alignment surface, and an alignment film was produced.

  Next, the liquid crystal solution was coated on the alignment film using a bar coater, dried at a drying temperature of 100 ° C. for 1 minute, and then cured using a high-pressure mercury lamp at an irradiation energy of 500 mj to obtain a retardation layer. . The thickness of the retardation layer after curing is about 1 μm.

  Next, the solution which melt | dissolved adhesive resin was apply | coated with the bar coater on the phase difference layer, and it dried at the drying temperature of 80 degreeC for 1 minute, and obtained the phase difference film for transcription | transfer.

[Forgery prevention medium]
A solution in which the fluorescent agent was dissolved in high-quality paper having a thickness of about 100 μm was applied using a bar coater and dried at 100 ° C. for 1 minute. The weight of the fluorescent agent at this time was 5 g / m ² .

  Next, the adhesive surface of the transfer phase difference layer and the fluorescent light emitting layer were faced to each other and bonded by a roll transfer machine, and then the base material PET of the transfer phase difference layer was peeled off.

  Next, a forgery prevention medium 10 was obtained by attaching a double-sided tape to the surface opposite to the surface provided with the retardation layer.

  The ink used, the composition of the material, and the name are shown below.

[Composition of alignment film ink]
10 parts by weight of polyvinyl alcohol resin (trade name: POVAL 117 manufactured by Kuraray Co., Ltd.)
Solvent (water / isopropyl alcohol = 95 parts / 5 parts) 100 parts by weight

[Rubbing cloth]
Product name FINE PUFF YA-20-R manufactured by Yoshikawa Chemical Co., Ltd.

[Composition of phase difference ink]
Liquid crystal (trade name: Paliocolor LC242 manufactured by BASF Corporation) 30 parts by weight polymerization initiator (trade name: manufactured by Irgacure 184 Ciba Geigy Co., Ltd.) 1.5 parts by weight solvent (toluene / MEK = 1/1) 68.5 Parts by weight

[Composition of ink for adhesive layer]
Adhesive (trade name: SK Dyne 1035, manufactured by Soken Chemical Co., Ltd.) 20 parts by weight solvent (toluene / MEK = 1/1) 80 parts by weight

[Composition of ink for fluorescent light emitting layer]
Acrylic resin (trade name: Dianal 100 manufactured by Mitsubishi Rayon Co., Ltd.) 20 parts by weight fluorescent dye (trade name: manufactured by Kayalight OS Nippon Kayaku Co., Ltd.) 0.3 parts by weight solvent (toluene / MEK = 1/1) 79 parts by weight

[Adhesive layer]
Product name No. 531 Nitto Denko Corporation

The latent image cannot be confirmed visually with the obtained anti-counterfeit medium. Place your filter comprising linearly polarized light child while irradiating with ultraviolet light using a black light onto the sample, an image portion with the fluorescence emission, the dark portion fluorescence was not observed was confirmed. Further, when the filter was rotated by 45 °, the brightness of the image area and the surrounding area was reversed.

  Next, when the counterfeit medium was copied with a color copier, the same appearance as the counterfeit medium could be duplicated, but no image could be confirmed even when the filter was layered while irradiating the duplicate with ultraviolet rays.

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Fluorescence emission layer 3 ... Adhesion layer 4 ... Phase difference layer 5 ... Adhesion layer 6 ... Orientation film 11 ... Linearly polarized light filter 12 ... Black light

Claims (6)

A fluorescent light-emitting layer that emits visible light when irradiated with ultraviolet light and a retardation layer formed by immobilizing liquid crystal are laminated in this order on one surface of the base material, and there is no reflective layer Anti-counterfeit medium.   An anti-counterfeit medium having a retardation layer formed by fixing a liquid crystal in which a phosphor that emits visible light when irradiated with ultraviolet rays is fixed on one surface of a substrate.   The forgery prevention medium according to claim 1, wherein the liquid crystal is a nematic liquid crystal or a smectic liquid crystal. The forgery prevention medium according to claim 1, wherein an alignment layer for controlling the alignment of the liquid crystal is formed between the base material and the retardation layer.   The forgery prevention medium according to any one of claims 1 to 4, wherein the other surface of the base material is subjected to adhesive processing. The medium for preventing forgery according to claims 1 to any one of the 5, characterized in that performing authenticity determination overlapping the polarizing filter while irradiating ultraviolet rays to the medium for preventing forgery.