JP5601040B2 - Anti-counterfeit media - Google Patents

Description

  The present invention relates to a machine-readable anti-counterfeit medium in which the described information is machine-readable under light irradiation in the infrared wavelength region.

  Conventionally, machine-readable code marks such as bar codes and OCR characters are provided as means for mechanically reading information described in securities such as stock certificates, bonds, checks, gift certificates, lotteries, and commuter passes. Many of these code marks are usually formed on the base material surface coated with white ink that reflects light in the near infrared region, using ink (black ink) containing carbon black that absorbs light in the near infrared region. Is done.

  In the above method, utilizing the infrared reflectivity and infrared absorptivity of the white ink and the black ink, mechanically readable information is applied to the medium as a barcode pattern mark, and infrared rays are applied to the medium. The recorded information is read by irradiating, scanning the mark, and measuring the intensity of the reflected infrared light. At this time, in some cases, a concealing layer that blocks visible light and transmits infrared rays is formed on the mark so that information is not read illegally by visible light.

  However, printed matter in which information is formed with the ink and the infrared ray is absorbed by the information portion has an advantage that it can be easily detected using various infrared rays in a wide wavelength range in the infrared region. However, since the ink is easily available, production evaluation and the like can be easily performed. As a result, it has a drawback that it is easy to read. That is, it can be easily read by an infrared information reader such as an infrared camera, and the presence of concealment information such as a code mark is determined. Therefore, based on the information read by the infrared camera, counterfeiting is performed using easily available ink, or by combining or pasting light-absorbing parts based on the reading results , Tampering may occur, which is a problem.

  To prevent forgery and tampering by determining the presence of concealment information, after mixing three types of black printing inks with different spectral characteristics from each other, printing the code mark etc. to solve the above problem In this case, two or more types of light sources or filters are used to capture the image printed with black printing ink on a single black and white screen, and the authenticity can be verified by reading each of the images. It will be judged. Similarly, it is possible to improve the anti-counterfeiting effect by using three types of black printing inks with different spectral absorption characteristics independently and providing one image as a whole. Each of the obtained images must be read and the authenticity determination must be performed, and there remains a problem that the operation for determining the authenticity becomes very difficult.

JP 2000-309736 A JP 2005-246719 A JP 2007-030448 A JP 2007-136983 A JP 2007-223285 A

  Solution of the problems of the prior art as described above, that is, easy and reliable operation for determining authenticity without easily reading information from a printed code mark or the like by visible light or infrared light Therefore, it is a problem to provide a machine-readable anti-counterfeit printed matter.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is such that the reflective layer whose reflection wavelength varies depending on the observation angle is coated with an infrared transmissive concealing layer on the substrate. The anti-counterfeit medium is characterized in that the concealing layer side is an observation surface .

  With this configuration, infrared rays propagate through the reflective layer and the concealing layer, but visible light is absorbed and reflected by the concealing layer, so that the reflective layer is not visually recognized.

  The invention according to claim 2 is the anti-counterfeit medium according to claim 1, characterized in that it has an embossed portion formed by embossing a part of the laminated portion of the base material and the reflective layer.

  In such a configuration, the reflection characteristics with respect to infrared rays are different between the embossed portion and the non-embossed portion.

  The invention according to claim 3 is the anti-counterfeit medium according to claim 1 or 2, wherein the reflective layer is a cholesteric liquid crystal layer, and the wavelength of the reflected light is in the infrared region. It is.

  The invention according to claim 4 is the multilayer interference film in which the reflective layer includes a reflective film at the bottom, and the wavelength of the reflected light is in the infrared region. This is a medium for preventing forgery.

  In the above two inventions, a cholesteric liquid crystal layer and a multilayer interference film are employed as the reflective layer exhibiting the viewing angle-dependent reflection characteristics.

  A fifth aspect of the present invention is the forgery prevention medium according to any one of the first to fourth aspects, wherein a part of the lower portion of the base material is covered with an infrared absorbing layer. It is a thing.

  With such a configuration, the transmitted infrared rays are absorbed and excessive reflection is reduced, so that the infrared reflection effect stands out and the contrast increases.

  The invention according to claim 6 provides the anti-counterfeit medium according to any one of claims 1 to 5, wherein the embossed portion includes an embossed portion having a right triangle shape in cross section. Is.

  The invention according to claim 7 is the forgery prevention medium according to any one of claims 1 to 5, wherein the embossed portion is a combination of two or more types of embossed portions having different cross-sectional shapes. It is what.

  Since the present invention is configured as described above, the following effects can be obtained.

It is well known that a reflective layer made of cholesteric liquid crystal shifts the wavelength of reflected light to a short wavelength depending on the incident angle of light with respect to the helical axis. Therefore, when detecting the infrared light reflected by the reflective layer, it is possible to detect the wavelength change peculiar to cholesteric liquid crystal by performing irradiation and detection at the first angle and irradiation and detection at the second angle. Judgment is possible.
Furthermore, by covering the cholesteric liquid crystal with a material that does not impair infrared transmission, the presence of the cholesteric liquid crystal can be concealed.

Further, by providing an embossed part and a non-embossed part, the cholesteric liquid crystal is in a state where the angle is changed with respect to the horizontal, for example, without tilting the medium, and further, infrared rays having different wavelengths without changing the angles of the infrared irradiator and the detector. Can be reflected.
Because of these combined effects, it becomes an anti-counterfeit medium that cannot be reproduced with materials such as infrared-absorbing dyes and carbon black, so that counterfeiting, tampering prevention and other fraud prevention, and unauthorized use determinations are made reliably. Become.

It is explanatory drawing which shows the planar state of one Example of the forgery prevention medium 10 of this invention. It is explanatory drawing which shows the general | schematic structure in the cross-section part by the XX 'line | wire of the forgery prevention medium of FIG. 1, a visual observation direction, and an observation means. It is explanatory drawing which shows how it looks when the irradiation light and detection light to the forgery prevention medium 10 of this invention are changed. (A): At 880 nm irradiation detection (b): At 780 nm irradiation detection.

  The present invention is a machine-readable anti-counterfeit medium in which information is provided in a state where the information cannot be visually confirmed, and information to be confirmed can be machine-readable under irradiation in an infrared wavelength region. More specifically, a reflection layer whose reflection wavelength changes according to a change in observation angle is provided as an infrared reflection layer that enables machine reading, and a concealing layer that makes the reflection layer invisible is formed. Furthermore, since at least a part of the reflective layer is embossed, the reflection angles of the non-embossed portion and the embossed portion change with respect to light incident at the same angle, and the reflection wavelength is also unique.

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

  FIG. 1 is an explanatory view showing an embodiment of the anti-counterfeit medium according to the present invention in a plan view, and FIG. 2 is a cross-sectional view of the anti-counterfeit medium shown in FIG. It is shown. FIG. 3 is a diagram showing how the anti-counterfeit medium of the present invention is seen when captured by an infrared camera and displayed on a monitor.

  Hereinafter, the material and forming method of each layer constituting the anti-counterfeit medium 10 according to the present invention will be specifically described. As shown in the lower diagram of FIG. 2, the anti-counterfeit medium 1 includes a base material 21, a light absorbing layer 22, a reflective layer 23, and a concealing layer 24, and an embossing process is performed on a part of the laminated portion of the base material 21 and the reflective layer 23. An embossed portion 25 is provided.

First, the substrate 21 may be polyethylene terephthalate (PET), triacetylcellulose (TAC), polyethylene naphthalate (PEN), polycarbonate (PC), polyethylene (PE), or polypropylene (PP) as a transparent substrate. .
In addition, white paper such as art paper, coated paper or high-quality paper, paperboard such as coated ball and coated manila, or special securities paper, white PET, white PVC sheet, etc. can be mentioned, and can be appropriately selected according to the use etc. . However, in the case of using an opaque base material such as the above-mentioned paper, it is necessary to install a light absorption layer below the reflective layer.

The light absorption layer 22 is preferably provided in order to further enhance the optical characteristics of the reflection layer 23, but may not be provided. The cholesteric liquid crystal forming the reflective layer 23 has the property of reflecting light of a specific wavelength and transmitting light of other wavelengths, but by absorbing the transmitted light in the light absorption layer 22, Only the reflected light can be seen clearly. The light absorption layer 22 is not particularly limited as long as it can absorb infrared rays transmitted through the reflection layer 23, and generally black using carbon is generally used. The light absorbing layer 22 may be formed as long as a sufficient concentration for absorbing light is obtained. The known gravure printing method, offset printing method, screen printing method, and other printing methods, bar coating methods, gravure methods, and roll coating methods. A coating method such as can be used.

  The shape of the embossed portion 25 is provided to reflect infrared rays having different wavelengths even when viewed from one direction, and the shape of the embossed portion 25 is preferably a right triangle or a shape close thereto. The embossed portion 25 is provided after the reflection layer is provided, and is used for controlling the reflection wavelength of the cholesteric liquid crystal by providing a certain angle to the reflection layer. The length of the oblique side of the embossed portion 24 can be set freely.

In addition, the angle of the emboss shape can be set as appropriate depending on the desired reflection wavelength, but the reflected light of the cholesteric liquid crystal shifts to the short wave side as it is incident from the vertical direction and tilts from the reflection angle, so that the reflected wavelength does not exceed the infrared region. Must be set to
That is, light from a direction perpendicular to the cholesteric liquid crystal installation surface is reflected perpendicularly at the non-embossed portion and reflected at an angle corresponding to the inclination at the embossed portion. The reflected light from the cholesteric liquid crystal shifts to the shorter wavelength side as it becomes horizontal with the cholesteric liquid crystal installation surface, so it is necessary to set the emboss angle so as not to enter the visible light region from the infrared region.
Moreover, if the depth of embossing is 2 times or more of the film thickness of a reflection layer, there will be no restriction | limiting in depth unless a base material is fractured | ruptured. The direction of embossing can be selected and used as appropriate, and can be applied in any combination of vertical and horizontal directions.

  The reflection layer 23 of the anti-counterfeit medium 10 is formed of a cholesteric liquid crystal or a multilayer interference film whose angle depends on optical characteristics, and has a feature that the reflection wavelength is changed by changing the incident reflection angle. Hereinafter, the cholesteric liquid crystal will be described. A multilayer interference film is formed by laminating many ceramics and plastics having different refractive indexes.

  A cholesteric liquid crystal layer having a helical axis that is right-handed or left-handed can be obtained by aligning and cross-linking three-dimensionally cross-linkable liquid crystal substance having a chiral phase. The light reflected by the cholesteric liquid crystal is circularly polarized light. Among liquid crystal substances, cholesteric liquid crystals have a twisted structure, and the refractive index of light periodically varies along the twisted axis (spiral axis), so that light with a wavelength equal to the pitch of the twisted structure is selectively reflected. To do. The pitch of the twisted structure can be set to a desired range by controlling the temperature, the type of chiral agent and the amount added.

In addition, a liquid crystal having a twisted structure has its molecules arranged in layers, and forms optical characteristics only when the molecules are uniformly arranged in the layer.
In this case, since the molecules continuously change the preferred direction with respect to the orientation direction for each layer, a twisted structure is generated. The orientation of each molecule can be controlled by a known method such as an orientation layer or an electric field, a magnetic field or a temperature.

  A typical method of immobilization is a combination of a three-dimensional cross-linkable liquid crystal having a chiral phase and a polyfunctional polymer compound, three-dimensional cross-linking by irradiation with ultraviolet rays, and a cholesteric structure in which a twisted structure is fixed. A polymer liquid crystal layer can be formed.

As the starting material for the cholesteric polymer liquid crystal, all cholesteric liquid crystal materials having a twisted structure with an equal pitch with respect to the wavelength of ultraviolet to infrared light can be used. That is,
A liquid crystal substance having a chiral phase can be produced by adding a chiral substance to a liquid crystal having a nematic or smectic structure. The direction and pitch of the twisted structure can be changed depending on the chiral substance to be added, so that the wavelength of the selectively reflected light can be determined. Further, if the liquid crystal has an irregular carbon in the structure, it is possible to spontaneously take a twisted structure without adding a chiral substance.

  Regardless of whether a chiral substance is added or not, changing the temperature is also effective for changing the pitch of the twisted structure. However, since the pitch is long when the temperature is low and short when the temperature is high, the reflected light enters the infrared region if the temperature is too low, and if it is high, it enters the ultraviolet region except for absorption by molecules, and isotropic layers. Therefore, in order to obtain necessary reflected light such as design properties and anti-counterfeiting properties, it is necessary to appropriately control the temperature depending on which wavelength is used.

  Further, the starting material has a polymerizable group, a polycondensable group or a group effective for polyaddition, and a conventionally known energy ray-curable compound is used. In particular, two or more energy rays are used in the molecule. It is preferable to contain the monomer and oligomer which have a sclerosing | hardenable group. Conventionally known as a radical photopolymerizable monomer, for example, polyfunctionality such as trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, etc. Other functional oligomers such as monomers, polyurethane polyacrylates, epoxy resin polyacrylates, acrylic polyol polyacrylates are preferred. Monofunctional monomers include alkyl (C1 to C18) (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, alkylene (C2 to C4) glycol (meth) acrylate, alkoxy (C1 to C10). ) Alkyl (C2 -C4) (meth) acrylate, polyalkylene (C2 -C4) glycol (meth) acrylate, alkoxy (C2 -C10) polyalkylene (C2 -C4) glycol (meth) acrylate, and the like. Examples of the cationic photopolymerizable monomer include conventionally known aromatic epoxy compounds, alicyclic epoxy compounds, and glycidyl ester compounds. More preferably, a three-dimensional crosslinkable liquid crystal polyorganosiloxane is used.

  As the polymerization initiator for causing energy ray curing used in the production of the cholesteric liquid crystal layer of the present invention, a known polymerization initiator having appropriate characteristics depending on the energy rays to be irradiated is used as necessary. For example, conventionally known photopolymerization initiators are used. As the radical photopolymerization initiator, known ones such as α-hydroxyacetophenone, α-aminoacetophenone, acetophenone, benzoin ether, benzyl ketal, α-dicarbonyl, α-acyl oxime ester, etc. are used. Specifically, α-aminoacetophenone, acetophenone diethyl ketal, benzyl dimethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylphenylpropanone, benzophenone, Michler's ketone, isopropylthioxanthone, benzophenone and N-methyldiethanolamine And the combination use with. Conventionally known cationic photopolymerization initiators can be used without particular limitation, and more preferably, known cationic sensitizers and peroxides can be used in combination as appropriate. For example, allyl iodonium salt-α-hydroxyacetophenone, triallylsulfonium salt, metallocene compound-peroxide combined system, metallocene compound-thioxanthone combined system, metallocene compound-anthracene combined system, and the like.

  The method for producing the cholesteric liquid crystal layer may be, for example, by first mixing a mixed solution of a three-dimensional crosslinkable liquid crystal polyorganosiloxane and a photopolymerization initiator with a known coating or printing method such as a comma coater or a micro gravure coater offset to a film thickness of 0.5 to The liquid crystal molecules are aligned by applying a shearing force on a metal support, plastic support or glass support so as to be 20 μm, preferably 2 to 10 μm.

Next, the liquid crystal layer is obtained by three-dimensional crosslinking by irradiating with ultraviolet rays using a known active energy ray irradiating apparatus such as a metal halide lamp and a high-pressure mercury lamp. In addition, in order to advance the crosslinking quickly, the active energy ray irradiation environment can be reduced by using an inert gas such as nitrogen to lower the oxygen concentration, or can be bonded to a film such as polyethylene to prevent oxygen inhibition.
The support may optionally have an alignment layer made of, for example, polyimide or polyvinyl alcohol.

  In addition, the liquid crystal molecules can be sheared between two sheets, preferably using polyethylene terephthalate.

  Alternatively, an adhesive may be applied to the liquid crystal surface of the cholesteric liquid crystal film constructed on the base material and transferred to another base material.

The concealing layer 25 is made of a material that does not impair the transmission of infrared rays, and has a function of concealing the presence of the reflective layer 23 made of cholesteric liquid crystal disposed under the concealing layer.
Generally, white pigments and phthalocyanines such as titanium oxide and galvanized are used if they are opaque so as to conceal the lower reflective layer 23 and the embossed portion 25, and if the thickness of the embossed layer cannot be confirmed. Pigments constituting a process ink such as an anthraquinone, an anthraquinone, or an azo are used, and known materials such as resins such as polyester and acrylic can be used as a binder.

Further, the hiding layer 24 may give the whole anti-counterfeit medium the function of reducing scratches and light deterioration. For this purpose, the hiding layer may be added with a UV absorber or a lubricant such as polyethylene wax. good. Moreover, you may add a leveling agent, an antifoamer, etc. suitably in the case of application | coating.
As a coating method, a known gravure printing method, an offset printing method, a coating method such as a screen printing method, or the like can be used.

  The anti-counterfeit medium according to the present invention may be provided with an adhesive layer as necessary. As the adhesive layer, a general adhesive material can be used as long as it does not change or damage the substrate in contact therewith. For example, vinyl chloride-vinyl acetate copolymer, polyester, polyamide, acrylic, butyl rubber, natural rubber, silicone, polyisobutyl adhesive alone, or alkyl methacrylate, vinyl ester, acrylonitrile, Addition of aggregating components such as styrene and vinyl monomers, unsaturated carboxylic acids, hydroxy group-containing monomers, modifying components such as acrylonitrile, polymerization initiators, plasticizers, curing agents, curing accelerators and antioxidants What added the agent as needed can be used. For the formation of this adhesive layer, a known gravure printing method, an offset printing method, a coating method such as a screen printing method, or the like can be used.

  Hereinafter, the present invention will be described in detail with reference to examples.

The following light-absorbing ink was formed on one surface of a 50 μm thick PET film by screen printing. A cholesteric liquid crystal forming a light reflecting layer having the following composition on the opposite surface of the substrate was subjected to gravure printing to a cured film thickness of 5 μm using a flat table calibrator and dried at 80 ° C. for 1 minute. Thereafter, it was irradiated with 500 mj with a high pressure mercury lamp and cured to obtain a light reflecting layer.
Thereafter, embossing was performed by pressing using an embossed plate having a right triangle shape as shown in the embossed portion 25 of FIG.

  Next, the anti-counterfeit sticker 10 was obtained by printing the concealing ink shown below by a screen printing method so as to have a dry film thickness of 10 μm.

[Light absorbing ink]
SS NSA 911 Black (Toyo Ink Manufacturing Co., Ltd.)
[Composition of ink containing light interference pigment]
Nematic liquid crystal (manufactured by Paliocolor LC242 BASF) 30 parts by weight chiral agent (manufactured by Paliocolor LC756 BASF) 0.7 parts by weight polymerization initiator (Irgacure 184, manufactured by Ciba Geigy) 1.5 parts by weight solvent (Methyl ethyl ketone) 67 parts by weight

[Concealment ink]
Hiding white ink (U-PET 450 white)

When the state of the anti-counterfeit medium was visually confirmed using an infrared camera while changing the infrared irradiation wavelength, the anti-counterfeit medium appeared as shown in FIG. 3A when the irradiation wavelength was 880 nm, and the irradiation wavelength was 780 nm. The anti-counterfeit medium sometimes looked as shown in FIG.
Since the wavelength of the light reflected from the non-embossed portion in the direction perpendicular to the cholesteric liquid crystal installation surface is substantially equal to the pitch of the cholesteric liquid crystal, the spiral pitch of the cholesteric liquid crystal of this embodiment is 880 nm.

1, non-embossed area 2, embossed area 3, embossed area 10, anti-counterfeit medium 20, anti-counterfeit medium 21, base material 22, light absorption layer 23, color shift layer 24, hiding layer 25, embossed portion 30, infrared irradiation, Detection device 31, monitor

Claims (7)

An anti-counterfeit medium characterized in that a reflection layer whose reflection wavelength varies depending on an observation angle on a base material is covered with an infrared transmitting shielding layer, and the shielding layer side is an observation surface .   The forgery prevention medium according to claim 1, further comprising an embossed portion formed by embossing a part of a laminated portion of the base material and the reflective layer.   The anti-counterfeit medium according to claim 1 or 2, wherein the reflective layer is a cholesteric liquid crystal layer, and a wavelength of reflected light is in an infrared region.   The anti-counterfeit medium according to claim 1 or 2, wherein the reflection layer is a multilayer interference film having a reflection film at a lower portion, and a wavelength of reflected light is in an infrared region.   The forgery prevention medium according to any one of claims 1 to 4, wherein a part of a lower portion of the base material is covered with an infrared ray absorbing layer.   The forgery prevention medium according to any one of claims 1 to 5, wherein the embossed portion includes an embossed portion having a cross-sectional shape of a right triangle. The forgery prevention medium according to any one of claims 1 to 5, wherein the embossed portion is a combination of two or more types of embossed portions having different cross-sectional shapes.

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