JP2010214671A - Recording medium capable of determining genuineness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording medium capable of determining genuineness with modifications made as to points such as insufficiency of forgery preventive effects and non-conspicuousness of and difficulty to read a recording part as an information recording medium. <P>SOLUTION: This recording medium 1 capable of determining genuineness has at least, a heat-sensitive breaking layer 4 and a cholesteric liquid crystal layer 5, laminated in that order, on one surface of a base 2. In addition, the recording medium 1 can demonstrate excellent forgery preventive effects by a constitution that a black layer 3 is formed between the heat-sensitive breaking layer 4 and the base 2 or on the other surface of the base 2. Since the non-recording part 10 which is not broken by heat sensing and the recording layer 9 which is broken by heat sensing are in sharp contrast with each other, the result is that the recording part 9 is conspicuous and easily legible. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording medium capable of authenticity determination, which is improved in that the anti-counterfeiting property is insufficient and the information recording medium is inconspicuous and difficult to read.

  Conventionally, authenticity is determined for economically valuable high-priced products, credit cards, traveler's checks, or vouchers that generate high value when used as ID (Identification) means. A hologram (label) suitable for the above is given to prevent forgery and prove as a genuine product. However, recently, holograms that are indistinguishable from the real one are manufactured, and new ones that prove authenticity are required.

  As an anti-counterfeiting measure, for example, as disclosed in Patent Document 1, as an identification medium provided on an object to identify the authenticity of the object, either left-handed polarized light or right-handed polarized light among incident light is used. As a light selective reflection layer that reflects only the light, it is described that the light selective reflection layer is formed by printing with cholesteric liquid crystal ink. Although it has been improved by the above method as a countermeasure against counterfeiting, it is not impossible to forge if a polymer cholesteric liquid crystal material is obtained, and it is still satisfactory as a method for preventing counterfeiting. I can't say that.

  Patent Document 2 discloses authenticity determination characterized by laminating at least two layers of a thin film layer whose light transmittance or reflectance changes by heating and a color change layer which gives different colors depending on the viewing angle. Media has been proposed. A cholesteric liquid crystal layer is presented as the color change layer. And it describes combining with an alignment film and a phase difference layer. However, the medium for authenticity determination is an alternative to a medium using a hologram, but recording is performed with the thin film layer removed, but there is a problem that the recording part has a low contrast and is difficult to read. .

JP 2000-25373 A JP 2006-58356 A

  Therefore, the present invention is a recording medium capable of determining authenticity, which is the above-mentioned problem and has an improved anti-counterfeit property and an improved information recording medium in which the recording portion is inconspicuous and difficult to read. The purpose is to provide.

  The present invention provides a recording medium in which at least a heat-sensitive destruction layer and a cholesteric liquid crystal layer are laminated on one surface of a base material in this order as claimed in claim 1, and between the heat-sensitive destruction layer and the base material. Or a recording medium capable of authenticating authenticity, characterized in that a black layer is provided on the other surface of the substrate. Thereby, the said subject was able to be solved.

  According to a second aspect of the present invention, there is provided a recording medium capable of authenticity determination according to the first aspect, wherein an alignment film is provided between the heat-sensitive destruction layer and the cholesteric liquid crystal layer. The medium is configured. Thereby, a cholesteric liquid crystal layer can be observed more vividly. Further, as claimed in claim 3, in the recording medium capable of determining authenticity according to claim 1 or 2, a heat-sensitive sensitizing layer is provided so as to be in contact with the substrate side of the heat-sensitive destruction layer. A recording medium capable of being falsely determined is configured. Thereby, at the time of thermal breakdown in information recording, the sensitivity of thermal breakdown of the thermal breakdown layer is increased, and clearer recording can be performed.

  The present invention relates to a recording medium in which at least a heat-sensitive destruction layer and a cholesteric liquid crystal layer are laminated in this order on one surface of a base material having the above-described structure, and between the heat-sensitive destruction layer and the base material. Alternatively, by providing a black layer on the other surface of the substrate, it has excellent anti-counterfeiting properties, and the contrast between the non-recording portion that is not thermally destroyed and the recording portion caused by thermal destruction is high. As a result, the recording unit is conspicuous and easy to read.

  In addition, in the recording medium with the above-described authenticity determination, by providing an alignment film between the heat-sensitive destruction layer and the cholesteric liquid crystal layer, the brightness, chromaticity, and contrast of the recording portion are high, and anti-counterfeiting is further achieved. In addition, the clearness of the recording portion is increased. In addition, in the recording medium with the above-described authenticity determination, by providing a heat-sensitive sensitizing layer so as to be in contact with the base material side of the heat-sensitive destruction layer, a heat-sensitive destruction is caused by a thermal head or a heating means such as laser irradiation. The layer can be easily destroyed by heat, the sensitivity of information recording by heating can be increased, and clear recording can be performed.

1 is a schematic cross-sectional view showing an embodiment of a recording medium capable of determining authenticity of the present invention. It is a schematic sectional drawing which shows other embodiment of the recording medium which can authenticate authenticity of this invention. It is a schematic sectional drawing which shows other embodiment of the recording medium which can authenticate authenticity of this invention. It is a schematic sectional drawing which shows other embodiment of the recording medium which can authenticate authenticity of this invention. It is a schematic sectional drawing which shows other embodiment of the recording medium which can authenticate authenticity of this invention.

  FIG. 1 is a schematic sectional view showing an embodiment of a recording medium capable of authenticating authenticity according to the present invention. FIG. 1 (1) shows the state before recording of the thermal breakdown layer, and FIG. 1 (2) shows the state after recording of the thermal breakdown layer in FIG. 1 (1). This is a recording medium 1 capable of authenticating authenticity in which a black layer 3, a heat-sensitive destruction layer 4, and a cholesteric liquid crystal layer 5 are sequentially laminated on one surface of a substrate 2. The heat-sensitive destruction layer 4 of the recording medium 1 capable of authenticity determination is heated and destroyed according to information to form the recording unit 9. On the other hand, the unheated portion of the heat-sensitive destruction layer 4 remains as the heat-sensitive destruction layer 4 as the non-recording portion 10 without being destroyed. Therefore, in the recording medium 1 capable of determining authenticity after recording, the recording unit 9 can observe a black layer as a background under the cholesteric liquid crystal layer 5. The non-recording portion 10 is in a state where the metal color of the heat-sensitive destruction layer 5 is observed under the cholesteric liquid crystal layer 5 without changing the state of the recording medium before recording, and the black layer cannot be seen at all. . Therefore, both the recording unit 9 and the non-recording unit 10 can observe the cholesteric liquid crystal layer 5, but the cholesteric liquid crystal layer has a black background in the recording unit and the metal of the heat-sensitive destruction layer in the non-recording unit. There is a color background, and the contrast is high due to the difference in hue between the black color and the metal color. As a result, the recording unit is conspicuous and easy to read. That is, in the non-recording portion, reflection occurs in the metal color portion of the heat-sensitive destruction layer, and in the recording portion, light is absorbed by the black layer positioned below and recognized as a black background.

  FIG. 2 is a schematic cross-sectional view showing another embodiment of the recording medium capable of determining authenticity of the present invention. A thermal breakdown layer 4 and a cholesteric liquid crystal layer 5 are sequentially formed on one surface of the substrate 2. This is a recording medium 1 that can be checked for authenticity in a configuration in which a black layer 3 is provided on the other surface of the base material 2 that is laminated. Also in this case, as in FIG. 1, FIG. 2 (1) shows the state before recording of the heat-sensitive destruction layer, and FIG. 2 (2) shows the state of FIG. The state after recording is shown. As shown in FIG. 2 (2), in the recording medium 1 capable of determining authenticity after recording, the recording unit 9 has a black layer as a background via a transparent base material 2 under the cholesteric liquid crystal layer 5. 3 can be observed. The non-recording portion 10 is in a state where the metal color of the heat-sensitive destruction layer 5 is observed under the cholesteric liquid crystal layer 5 without changing the state of the recording medium before recording, and the black layer cannot be seen at all. . Therefore, both the recording portion 9 and the non-recording portion 10 can observe the cholesteric liquid crystal layer 5, but the cholesteric liquid crystal layer has a black background in the recording portion and the metal of the heat-sensitive destruction layer in the non-recording portion. There is a color background, and the contrast is high due to the difference in hue between the black color and the metal color. As a result, the recording unit is conspicuous and easy to read.

  FIG. 3 is a schematic cross-sectional view showing another embodiment of a recording medium capable of determining authenticity of the present invention. On one surface of the substrate 2, a black layer 3, a thermal breakdown layer 4, an alignment film 6, This is a recording medium 1 in which authenticity determination is possible by sequentially laminating cholesteric liquid crystal layers 5. In this case as well, as in FIG. 1, FIG. 3 (1) shows the state before recording of the heat-sensitive destruction layer, and FIG. 3 (2) shows the state of FIG. The state after recording is shown. In FIG. 3, the recording medium shown in FIG. 1 is provided with an alignment film 6 between the heat-sensitive destruction layer 4 and the cholesteric liquid crystal layer 5, so that the cholesteric liquid crystal layer can be observed more vividly, and as a result, the recording portion Brightness, chromaticity, and contrast can be increased.

  FIG. 4 is a schematic cross-sectional view showing another embodiment of a recording medium capable of authenticity determination according to the present invention. On one surface of the substrate 2, a thermal breakdown layer 4, an alignment film 6, a cholesteric liquid crystal are shown. The recording medium 1 has a configuration in which the layers 5 are sequentially laminated, and the black layer 3 is provided on the other surface of the substrate 2. In this case, as in FIG. 1, FIG. 4 (1) shows the state before recording of the heat-sensitive destruction layer, and FIG. 4 (2) shows the state of FIG. The state after recording is shown. In FIG. 4, the recording medium shown in FIG. 2 is provided with an alignment film 6 between the heat-sensitive destruction layer 4 and the cholesteric liquid crystal layer 5, so that the cholesteric liquid crystal layer can be observed more vividly, and as a result, the recording portion Brightness, chromaticity, and contrast can be increased.

  FIG. 5 is a schematic cross-sectional view showing another embodiment of the recording medium capable of authenticity determination according to the present invention. On one surface of the substrate 2, a black layer 3, a heat-sensitive sensitizing layer 7, a heat-sensitive destruction layer. 4 is a recording medium 1 in which authenticity determination is possible, in which an alignment film 6, a cholesteric liquid crystal layer 5, and a protective layer 8 are sequentially laminated. Also in this case, similarly to the case of FIG. 1, FIG. 5 (1) shows the state before recording of the heat-sensitive destruction layer, and FIG. 5 (2) shows the state of FIG. The state after recording is shown. In FIG. 5, the recording medium shown in FIG. 3 is provided with a heat-sensitive sensitizing layer 7 between the black layer 3 and the heat-sensitive destruction layer 4, and a protective layer 8 on the cholesteric liquid crystal layer 5. The thermal destruction of the heat-sensitive destruction layer easily occurs, the sensitivity of information recording by heating is high, and the protective layer is provided on the outermost surface of the recording medium, so that the durability becomes high in handling. For example, in FIGS. 1 to 4, a protective layer is added to the position of the outermost surface of the recording medium on the cholesteric liquid crystal layer. It is possible to provide a heat-sensitive sensitizing layer so as to be in contact with the substrate.

Hereinafter, each layer constituting the recording medium capable of determining authenticity of the present invention will be described in detail.
(Base material)
The substrate 2 used in the recording medium capable of authenticity determination in the present invention is made of a sheet-like, film-like or plate-like material, and the material is not particularly limited. Polyethylene terephthalate (PET), nylon , Cellulose diacetate, polystyrene, polyethylene, polypropylene, polyester, polyimide, polyvinyl chloride, polycarbonate and other plastics, copper, aluminum and other metals, paper, impregnated paper, etc. it can. An appropriate thickness of the substrate is about 0.005 to 5 mm. However, as in the recording medium shown in FIGS. 2 and 4, the thermal breakdown layer 4 and the cholesteric liquid crystal layer 5 are provided on one surface of the base material 2, and the black layer 3 is provided on the other surface of the base material 2. In the case of the above configuration, the base material to be used has transparency, that is, transparency so that the recording layer of the heat-sensitive destruction layer can pass through the base material and observe the underlying black layer.

(Black layer)
The black layer 3 used in the recording medium capable of determining authenticity of the present invention can be a layer containing a black color material such as carbon black in a binder. Examples of black color materials include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, Examples thereof include ferrite (nonmagnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, complex oxide black pigment, anthraquinone organic black pigment. These color materials can be used alone or in combination of two or more.

As the binder in the black layer, polyamide resin, phenol resin, alkyd resin, vinyl resin, acrylic resin, nitrocellulose, or a mixture thereof can be used. The black layer can be formed using a coating liquid in which a colorant such as a binder resin and carbon black is dissolved or dispersed in a solvent. Coating is performed by a general method such as a roll coater method, a reverse coater method, a knife coater method, a comma coater method, or a gravure coater method. The coating amount is preferably 0.1 to 10 g / m ² (dry state).

(Thermal destruction layer)
The heat-sensitive destruction layer 4 used in the recording medium capable of determining authenticity according to the present invention is printed by being broken by a heating means such as a thermal head. Specifically, the thermal breakdown layer is formed by vacuum deposition of a metal such as Fe, Co, Ni, Te, Sn, In, Al, Bi, Pb, Zn, Cu, Cr, Ti, or a mixture thereof. The film can be formed by a method, a sputtering method, a plating method, or the like. The thickness of the heat-sensitive fracture layer is about 100 to 1 μm, preferably about 500 to 1000 mm.

(Cholesteric liquid crystal layer)
The cholesteric liquid crystal layer 5 used in the recording medium capable of determining authenticity of the present invention is obtained by forming cholesteric liquid crystal into an ink on the above-mentioned base material, intaglio printing such as gravure printing, planographic printing such as offset method, letterpress It can be formed by printing, screen printing, or the like. The thickness of the formed cholesteric liquid crystal layer is preferably about 1 μm to 20 μm. The mass per unit area is about 1 to 20 g / m ² when dried. If the thickness is too small, the two characteristics of circularly polarized light selectivity and selective reflection characteristic peculiar to cholesteric liquid crystals cannot be fully exhibited. If the thickness is too thick, the orientation of the liquid crystal is lowered, which is also disadvantageous in terms of cost. . The cholesteric liquid crystal layer is not only provided as a single layer, but also two or more layers can be laminated. For example, a cholesteric liquid crystal “HELICONE (registered trademark)” manufactured by Wacker Chemie, Inc. can be used as the cholesteric liquid crystal material.

  The cholesteric liquid crystal used in the present invention has a regular twist so that the alignment structure of liquid crystal molecules draws a spiral in the film thickness direction. A cholesteric liquid crystal has two optical properties of selective reflectivity and circular polarization selectivity when the pitch P (the film thickness necessary for the liquid crystal molecules to rotate 360 °) and the wavelength λ of incident light are substantially equal. It is known to exhibit properties. (Reference: Basics of liquid crystal and display applications, Corona, etc.)

Selective reflectivity refers to the property of strongly reflecting light within a specific wavelength band of incident light. Since the selective reflectivity is limited and expressed within a specific wavelength band, the reflected light becomes a chromatic color with high color purity by appropriately selecting the pitch P of the polymer cholesteric liquid crystal. If the center wavelength of the band is λ _S and the bandwidth is Δλ, these are the pitch P (= λ / n _m ) and average refractive index n _m (= √ ((ne ² + no ² ) / 2) of the optical medium. ) Is determined as in the following formulas (1) and (2). Here, Δn is the difference between the extraordinary ray refractive index ne in the plane of the optical medium and the ordinary ray refractive index no (Δn = ne−no).
λ _S = n _m · P (1)
Δλ = Δn · P / n _m (2)

The center wavelength λ _S and the wavelength bandwidth Δλ shown in the above formulas (1) and (2) are defined when the incident light to the cholesteric liquid crystal layer is vertically incident (0 ° incidence, on-axis incidence). When the incident light is obliquely incident (off-axis incident), the pitch P apparently decreases, so that the center wavelength λ _S shifts to the short wavelength side, and the wavelength bandwidth Δλ decreases. This phenomenon is called blue shift because λ _S shifts to the short wavelength side, and the shift amount depends on the incident angle, but can be easily identified by visual observation. For example, the reflected color of a cholesteric liquid crystal that is colored red when viewed from the vertical (0 ° incident position) changes in order of orange, yellow, green, blue-green, and blue as the viewing angle increases. Observed. In this way, the cholesteric liquid crystal layer shifts to the short wavelength side depending on the viewing angle, and shows (changes) a special color that cannot be reproduced by color copying. It is a thing.

  Further, in the recording medium capable of determining authenticity of the present invention, the above-described cholesteric liquid crystal layer, the heat-sensitive destruction layer and the black layer are indispensable components, and information is recorded on the heat-sensitive destruction layer by heating a thermal head or the like. The thermal destruction layer is destroyed according to the recording, the black layer hidden underneath is exposed, and the difference in hue between the background of the black layer and the thermal destruction layer becomes clear, The recording part is conspicuous and easy to read. Furthermore, by combining the cholesteric liquid crystal layer, the heat-sensitive destruction layer, and the black layer, the recording part and the non-recording part of the heat-sensitive destruction layer become unique due to the difference in the background hue between the black layer and the heat-sensitive destruction layer, It has a very high anti-counterfeiting property.

  Since the cholesteric liquid crystal layer shows a unique reflection color, it is possible to easily determine whether the recording medium using the liquid crystal layer is true or false, and also has circular polarization selectivity. , Selectively reflects either left circularly polarized light or right circularly polarized light. The circularly polarized light selectivity means a property of transmitting only circularly polarized light in a specific rotation direction and reflecting circularly polarized light having the opposite rotation direction. Of the incident light, the circularly polarized light component in the same direction as the twist direction of the alignment structure of the cholesteric liquid crystal is reflected, and the rotational direction of the reflected light is also the same direction, while the circularly polarized light component rotating in the opposite direction is transmitted. Is a unique property unique to cholesteric liquid crystals. In the case of a cholesteric liquid crystal having a left twisted structure, the left circularly polarized light is reflected, the reflected light remains as the left circularly polarized light, and the right circularly polarized light is transmitted. In the case of a cholesteric liquid crystal having a right twist structure, right circularly polarized light is reflected, reflected light remains right circularly polarized light, and left circularly polarized light is transmitted.

  The liquid crystal material used for the cholesteric liquid crystal layer in the recording medium of the present invention is, for example, a side chain polymer such as polyacrylate, polymethacrylate, polysiloxane, polymalonate having a liquid crystal forming group in the side chain, and a liquid crystal forming group in the main chain. Main chain polymers such as polyester, polyesteramide, polycarbonate, polyamide, polyimide, etc. can be mentioned. The polymer cholesteric liquid crystal layer in the aligned state has a property of reflecting either left circularly polarized light or right circularly polarized light in incident light. Also, it has an effect that the hue looks different depending on the viewing angle. A cholesteric liquid crystal layer can be formed by applying a solvent solution of this cholesteric liquid crystal material by various printing methods and drying, or, at this time, using a polymerizable cholesteric liquid crystal, The ultraviolet polymerizable composition prepared and obtained can be applied by various printing methods, and after drying, it can be polymerized by irradiation with ultraviolet rays. The light selective reflection layer made of a cholesteric liquid crystal layer has transparency, except that the hue looks different depending on the viewing angle, and in that sense, has transparency.

  In order to realize the alignment state, an ultraviolet polymerizable composition prepared using a solvent solution of cholesteric liquid crystal or polymerizable cholesteric liquid crystal is applied to the surface of the stretched plastic sheet, or an alignment film is formed on the surface of the object. After the formation, an ultraviolet polymerizable composition prepared by using a cholesteric liquid crystal solvent solution or a polymerizable cholesteric liquid crystal may be applied. When two or more light selective reflection layers are provided, the thickness of the layers, the helical pitch of the material, and the like can be configured differently to give more complicated optical characteristics. Alternatively, since the light selective reflection layer can be formed in a pattern, one may be formed as a uniform layer and the other may be formed in a pattern.

  As the polymerizable cholesteric liquid crystal, specifically, a liquid crystal material (liquid crystal compound) described in JP-A-2006-53356 can be used. Furthermore, a clearer color can be observed by adding a chiral agent to the liquid crystalline compound. As this chiral agent, specifically, those having the chemical formula described in JP-A-2006-53356 can be used.

(Alignment film)
In the recording medium capable of determining authenticity of the present invention, the luminance, chromaticity and contrast of the recording portion can be increased by providing the alignment film 6 between the heat-sensitive destruction layer and the cholesteric liquid crystal layer. The alignment film may be composed of any material as long as it can be generally used as an alignment film, such as polyvinyl alcohol resin (PVA) or polyimide resin. The alignment film can be formed by applying a solvent solution of these resins to the surface of a substrate such as a plastic film by an appropriate application method and drying, followed by rubbing with a cloth, a brush, or the like. it can.

(Thermosensitive layer)
In the recording medium capable of determining authenticity of the present invention, by providing the heat-sensitive sensitizing layer 7 so as to be in contact with the base material side of the heat-sensitive destruction layer, the heat-sensitive destruction layer is formed by a thermal head or heating means such as laser irradiation. Can be easily destroyed, the sensitivity of information recording by heating can be increased, and clear recording can be performed. Specifically, the heat-sensitized layer is mainly made of a resin such as polyester resin, polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, polymethyl methacrylate (PMMA), polyurethane resin, and epoxy resin. Configure as an ingredient. Further, in order to improve the durability of the recording medium, a plasticizer or an isocyanate curing agent can be added to the above resin.

(Protective layer)
In the recording medium capable of determining authenticity of the present invention, the protective layer 8 can be provided on the cholesteric liquid crystal layer so that the surface of the recording medium is not damaged or does not cause a problem in handling. As the protective layer, those generally known for forming the protective layer can be used. In addition to a thermoplastic resin or a thermosetting resin used as a binder resin in ink or paint, an ionizing radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin can be used.

(Recording information)
In the present invention, information is recorded on the above-described recording medium capable of determining authenticity by heating with a thermal head or heating with laser light to destroy and remove the heat-sensitive destruction layer. Examples of the recorded information include fixed information and variable information that is different information for each recording medium. In the present invention, it is preferable to record variable information in order to improve forgery prevention. This variable information includes the date of manufacture, product name, name, address, and other items to which the recording medium is given (high-priced products, identification cards, credit cards, savings cards, prepaid cards, commuter passes, traveler's checks Or individual data specifying the type of the recording medium itself.

  In the recording medium described above, the information is obtained by destroying and removing the thermal destruction layer by heating with a thermal head or irradiating a laser beam, heating the thermal destruction layer, melting or decomposing it, and so on. To be recorded. That part is the recording part and the other part is the non-recording part, but the black layer is exposed in the recording part, but the heat-sensitive destruction layer remains in the non-recording part, and the black layer is hidden. Has been. Accordingly, the cholesteric liquid crystal layer is observed with the black layer as the background in the information recording portion, and the cholesteric liquid crystal layer is observed with the heat-sensitive destruction layer as the background in the non-recording portion. Thus, the contrast of the cholesteric liquid crystal layer is high due to the difference in color between the black color of the black layer and the metal color of the heat-sensitive destruction layer, and as a result, the recording portion is conspicuous and easy to read.

  Hereinafter, the authenticity determination recording medium of the present invention will be described in detail with reference to examples.

Example 1
A transparent polyethylene terephthalate film having a thickness of 16 μm is used as a base material, and a black layer having a thickness of 5 g / m ² is formed on one side of the base material by a gravure coating method using a black layer ink having the following composition. Further, Sn was formed on the black layer as a thermal destruction layer with a thickness of 500 mm by vacuum deposition.
(Black layer ink)
Carbon black 12 parts Polyamide resin 88 parts Methyl ethyl ketone 20 parts Toluene 20 parts

A cholesteric liquid crystal layer having a thickness of 10 g / m ² is formed on the heat-sensitive destruction layer by printing with a screen printing method using a cholesteric liquid crystal layer ink having the following composition and irradiating with ultraviolet rays immediately after printing. Then, a recording medium capable of determining authenticity of Example 1 having the configuration as shown in FIG. 1 was produced.
(Cholesteric liquid crystal layer ink)
Cholesteric liquid crystal pigment (Wacker Chemie, HELICONE (registered trademark) HCXL) 30 parts Medium ink (The Inktec Co., Ltd., UV card) 70 parts

(Example 2)
A transparent polyethylene terephthalate film having a thickness of 16 μm is used as a base material, and the black layer ink used in Example 1 is used on one surface of the base material by a gravure coating method to obtain a thickness of 5 g / m ² at the time of drying. A black layer was formed. On the opposite side of the surface of the base material where the black layer was formed, Sn was formed as a heat-sensitive destruction layer with a thickness of 500 mm by vacuum deposition, and the cholesteric used in Example 1 was formed on the heat-sensitive destruction layer. Example of a configuration as shown in FIG. 2 by using a liquid crystal layer ink and printing by a screen printing method, irradiating ultraviolet rays immediately after printing to form a cholesteric liquid crystal layer having a thickness of 10 g / m ² at the time of drying. Two recording media capable of authenticity determination were produced.

Example 3
A transparent polyethylene terephthalate film having a thickness of 16 μm is used as a base material, and the black layer ink used in Example 1 is used on one surface of the base material by a gravure coating method to obtain a thickness of 5 g / m ² at the time of drying. A black layer was formed, and Sn was formed on the black layer as a heat-sensitive destruction layer with a thickness of 500 mm by a vacuum deposition method. In addition, a polyvinyl alcohol resin solution (PVA resin manufactured by Kuraray Co., Ltd., product number: “110”, used as a 5% aqueous solution (transparent)) is applied on the heat-sensitive destruction layer, dried, and then rubbed. Processing was performed to form an alignment film. On this alignment film, the cholesteric liquid crystal layer ink used in Example 1 was used for printing by screen printing, irradiated with ultraviolet rays immediately after printing, and a cholesteric liquid crystal layer having a thickness of 10 g / m ² was dried. Thus, a recording medium capable of determining authenticity of Example 3 having a configuration as shown in FIG. 3 was produced.

Example 4
A transparent polyethylene terephthalate film having a thickness of 16 μm is used as a base material, and the black layer ink used in Example 1 is used on one surface of the base material by a gravure coating method to obtain a thickness of 5 g / m ² at the time of drying. A black layer was formed. On the side opposite to the surface on which the black layer was formed, Sn was formed as a thermal destruction layer with a thickness of 500 mm by vacuum deposition, and the orientation formed in Example 3 on the thermal destruction layer. An alignment film was formed in the same manner as the film. On the alignment film, the cholesteric liquid crystal layer ink used in Example 1 was printed by screen printing, irradiated with ultraviolet rays immediately after printing, and a cholesteric liquid crystal layer having a thickness of 10 g / m ² when dried. A recording medium capable of determining authenticity of Example 4 having the configuration as shown in FIG. 4 was produced.

(Example 5)
A transparent polyethylene terephthalate film having a thickness of 16 μm is used as a base material, and the black layer ink used in Example 1 is used on one surface of the base material by a gravure coating method to obtain a thickness of 5 g / m ² at the time of drying. A black layer was formed, and a heat-sensitive sensitizing layer having a thickness of 1 g / m ² was formed on the black layer by a gravure coating method using a heat-sensitive sensitizing layer ink having the following composition.
(Heat-sensitive layer ink)
Vinyl chloride-vinyl acetate copolymer (manufactured by Union Carbide, VAGH) 20 parts Acrylic resin (manufactured by DIC Corporation, ACRYDIC A-136-55) 10 parts Methyl ethyl ketone 20 parts Toluene 30 parts Butyl alcohol 20 parts

Then, Sn was formed as a heat-sensitive destruction layer with a thickness of 500 mm on the heat-sensitive sensitized layer by a vacuum deposition method. In addition, an alignment film was formed on the heat-sensitive destruction layer in the same manner as the alignment film formed in Example 3. On the alignment film, the cholesteric liquid crystal layer ink used in Example 1 was printed by screen printing, irradiated with ultraviolet rays immediately after printing, and a cholesteric liquid crystal layer having a thickness of 10 g / m ² when dried. Formed. Further, on the cholesteric liquid crystal layer, a urethane resin-based protective layer is formed at a dry thickness of 2 g / m ² by gravure printing, and the authenticity determination of Example 5 having the configuration as shown in FIG. A possible recording medium was produced.

  Using the thermal head and the platen roll, the thermal head heated by the thermal head toward the cholesteric liquid crystal layer side with respect to each of the recording media capable of determining authenticity in Examples 1 to 5 above. Went and recorded. In the recording media of Examples 1 and 2, the recording unit 9 can observe a black layer as a background under the cholesteric liquid crystal layer 5. The non-recording portion 10 is in a state where the metal color of the heat-sensitive destruction layer 5 is observed under the cholesteric liquid crystal layer 5 without changing the state of the recording medium before recording, and the black layer cannot be seen at all. . Therefore, both the recording unit 9 and the non-recording unit 10 can observe the cholesteric liquid crystal layer 5, but the cholesteric liquid crystal layer has a black background in the recording unit and the metal of the thermal breakdown layer in the non-recording unit. There was a color background, and the contrast was high due to the difference in hue between the black color and the metal color. As a result, the recording part was conspicuous and easy to read.

  In the recording media of Examples 3 and 4, the alignment film 6 is provided between the heat-sensitive destruction layer 4 and the cholesteric liquid crystal layer 5, so that the cholesteric liquid crystal layer can be observed more vividly, resulting in recording. The brightness, chromaticity, and contrast of the part were higher than those of the recording media of Examples 1 and 2. In the recording medium of Example 5, the heat-sensitive sensitizing layer 7 is provided between the black layer 3 and the heat-sensitive destruction layer 4, and the protective layer 8 is provided on the cholesteric liquid crystal layer 5. Since the thermal destruction of the layer occurs easily, the sensitivity of information recording by heating is increased as compared with the recording media of Examples 1 to 4, and the protective layer is provided on the outermost surface of the recording medium. The recording medium was more durable than the recording medium, such as being less susceptible to scratches on the surface. The recording media in Examples 1 to 5 were all excellent in prevention of counterfeiting, and the products (products) to which these recording media were applied could be proved as authentic products and were very useful. That is, the recording medium of the present invention provides a highly reliable proof when determining authenticity.

DESCRIPTION OF SYMBOLS 1 Recording medium in which authenticity can be judged 2 Base material 3 Black layer 4 Heat-sensitive destruction layer 5 Cholesteric liquid crystal layer 6 Orientation film 7 Heat-sensitive sensitizing layer 8 Protective layer 9 Recording part 10 Non-recording part

Claims (3)

  In a recording medium capable of authenticity determination, in which at least a heat-sensitive destruction layer and a cholesteric liquid crystal layer are laminated in this order on one surface of the base material, between the heat-sensitive destruction layer and the base material, or on the other side of the base material A recording medium capable of determining authenticity, wherein a black layer is provided on the surface.   The recording medium according to claim 1, wherein an alignment film is provided between the heat-sensitive destruction layer and the cholesteric liquid crystal layer. 3. A recording medium capable of authenticity determination according to claim 1, wherein a heat-sensitive sensitizing layer is provided so as to be in contact with the base of the heat-sensitive destruction layer.

Images