JP5380773B2 - Laminated body, adhesive label, transfer foil, recording medium, labeled article, kit, and discrimination method - Google Patents

Description

  The present invention relates to a discrimination technique for discriminating an article between a genuine product and a non-genuine product.

  It is desired that counterfeiting is difficult for authentication media such as cash cards, credit cards and passports, and securities media such as gift certificates and stock certificates. Therefore, conventionally, a label that is difficult to forge is attached to such a medium in order to prevent the forgery.

  In recent years, the distribution of counterfeit products has been regarded as a problem for articles other than authentication media and securities media. Therefore, the opportunity to apply the above-described anti-counterfeiting technology for authentication media and securities media to such articles is increasing.

The forgery prevention technology can be classified into an overt technology and a covert technology.
The overt technique is an anti-counterfeiting technique that allows a general user to easily recognize application to an article and easily determine whether it is authentic. In a typical overt technique, a diffractive structure such as a hologram or a multilayer interference film such as Optically Variable Ink (OVI) is used.

  The covert technique is an anti-counterfeiting technique aimed at making it possible for only a specific user who knows the application of the covert technique to an article to make an authenticity determination because it is difficult for a general user to apply to the article. Typical covert techniques use fluorescent printing or line moire.

  Patent Document 1 describes another covert technique. In this covert technique, a label including a reflective layer, an alignment film, and a birefringent layer is used. The alignment film is formed on the front surface of the reflective layer, and includes two portions whose alignment directions are different by 45 °. The birefringent layer is made of a polymer liquid crystal material formed on the alignment film. The birefringent layer includes two portions corresponding to the two portions of the alignment film, the directions of the slow axis differing by 45 °, and each serving as a quarter-wave plate.

  When this label is observed without passing through a polarizing film, it is difficult to distinguish a region corresponding to one part of the birefringent layer and a region corresponding to the other part. When viewed through a polarizing film, one of these regions appears darker than the other region. Using the visible image formed by the bright and dark parts, the authenticity of the article supporting the label is confirmed.

  By the way, it is desired that the label is thin. For example, thin labels can be easily made brittle by forming notches and / or perforations. Such labels are easily destroyed when trying to peel from the article. Therefore, it is difficult to replace the label. Also, if the label is made thinner, the amount of material used is reduced.

However, for example, when the birefringent layer of the label is thinned, the contrast ratio of the visualized latent image is lowered. That is, if the birefringent layer is thinned, the visualized latent image becomes difficult to see.
JP-A-8-43804

  An object of the present invention is to make it possible to thin a birefringent layer without impairing the visibility of a visualized latent image.

According to the first aspect of the present invention, the reflective layer, the first birefringent portion facing a part of the front surface of the reflective layer, and the other portion of the front surface and the first birefringent portion are delayed. A birefringent layer including a second birefringent portion having a different phase axis direction, and a cholesteric liquid crystal layer interposed between the reflective layer and the birefringent layer. If each of the two birefringent portion where the retardation of when the wavelength λ is 550nm Ri range near the 3 [lambda] / 32 to 5 [lambda] / 32, saw the front of the reflective layer from the normal direction, the first birefringent portion overlaps only partially with the cholesteric liquid crystal layer, the second birefringent portion identifying laminates only partially characterized that you have overlapped with the cholesteric liquid crystal layer Is provided.
According to the second aspect of the present invention, the reflective layer, the first birefringent portion facing a part of the front surface of the reflective layer, and the other portion of the front surface and the first birefringent portion are delayed. A birefringent layer including a second birefringent portion having a different phase axis direction, and a cholesteric liquid crystal layer interposed between the reflective layer and the birefringent layer. Each of the two birefringent portions has a retardation in the range of 3λ / 32 to 5λ / 32 when the wavelength λ is 550 nm, and includes a light absorbing layer interposed between the reflective layer and the cholesteric liquid crystal layer. Furthermore, the identification laminated body characterized by having comprised is provided.

According to a third aspect of the present invention, there is provided an adhesive label comprising the identification laminate according to the first or second aspect and an adhesive layer supported on the back surface of the identification laminate. The

According to the fourth aspect of the present invention, the paper, the adhesive layer supported on one main surface of the paper, and the first or second side surface embedded in the paper so that the back surface faces the adhesive layer. A pressure-sensitive adhesive label comprising the identification laminate according to claim 1 is provided.

According to the fifth aspect of the present invention, the base material, the identification laminate according to the first or second side surface that is releasably supported by the base material, and the back surface of the identification laminate are supported. A transfer foil comprising an adhesive layer is provided.

According to a sixth aspect of the present invention, there is provided a recording medium comprising a paper and the identification laminate according to the first or second side embedded in the paper.

According to the seventh aspect of the present invention, there is provided an article whose authenticity is to be confirmed and an identification laminate according to the first or second aspect supported by the article whose authenticity is to be confirmed. A featured labeled article is provided.

According to an eighth aspect of the present invention, there is provided a verification tool including the identification laminate according to the first aspect, a linear polarizer, and a second birefringent layer facing the light incident surface of the linear polarizer. And the sum of the retardation at the wavelength λ of the first birefringent portion and the retardation at the wavelength λ of the second birefringent layer is λ / 4, The security kit is characterized in that the sum of the retardation at the wavelength λ and the retardation of the second birefringent layer at the wavelength λ is λ / 4.

According to a ninth aspect of the present invention, there is provided a method for discriminating an article whose authenticity is unknown between an authentic product and a non-authentic product, the authentic product including an article whose authenticity is to be confirmed, and the authentic product. A labeled article comprising a discriminating laminate according to the first side supported by an article to be confirmed, which is visible by observing the article whose authenticity is unknown through a verification tool Discriminating between the genuine product and the non-genuine product based on an image, the verification tool comprising: a linear polarizer; and a light incident surface of the linear polarizer; and a second birefringent layer facing, Ruri terpolymers put a retardation in the wavelength λ of each of the first and second birefringent portion, the wavelength λ of the second birefringent layer A method is provided characterized in that the sum with the day is λ / 4.

  According to the present invention, the birefringent layer can be made thin without impairing the visibility of the visualized latent image.

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

  FIG. 1 is a plan view schematically showing the identification laminate according to the first aspect of the present invention. 2 is a cross-sectional view taken along the line II-II of the laminate shown in FIG.

  As shown in FIG. 2, the identification laminate 10 includes a base material 16, a reflective layer 13 b, a cholesteric liquid crystal layer 19, an alignment film 17, and a birefringent layer 12. The reflective layer 13 b, the cholesteric liquid crystal layer 19, the alignment film 17, and the birefringent layer 12 are sequentially stacked on the substrate 16.

  The base material 16 is a resin film, for example. As a material for the resin film, for example, polyethylene terephthalate, polypropylene, triacetyl cellulose, and polyethylene naphthalate can be used. The thickness of the resin film is, for example, in the range of 12 μm to 200 μm. The substrate 16 can be omitted.

  The reflective layer 13b is, for example, a metal layer, an alloy layer, or a high refractive index layer. As the material for the metal layer, for example, aluminum, tin, silver, chromium, nickel, and gold can be used. As a material of the alloy layer, for example, nickel-chromium-iron alloy, bronze, and aluminum bronze can be used. As a material for the high refractive index layer, for example, an inorganic dielectric such as titanium dioxide, zinc sulfide, and ferric trioxide can be used. As the reflective layer 13b, a dielectric multilayer film in which high refractive index layers and low refractive index layers are alternately stacked may be used.

  When the base material 16 is used, the reflective layer 13 b can be formed on the base material 16. The reflective layer 13b can be formed by, for example, vapor deposition, sputtering, or ion plating. The thickness of the reflective layer 13b is, for example, in the range of about 10 nm to about 100 nm. The reflective layer 13b can be formed as a layer patterned by using, for example, paster processing, water-washed celite processing, or laser processing. That is, the reflective layer 13 b may cover the entire front surface of the base material 16, or may cover only a part of the front surface of the base material 16.

  When the base material 16 is omitted, the reflective layer 13b may be formed on the birefringent layer 12 or the like, as will be described later for the transfer foil. In this case, the reflective layer 13b can be formed by the same method as described above. Or when the base material 16 is abbreviate | omitted, what can handle itself independently like a metal foil and a ceramic board may be used as the reflection layer 13b.

  In the case where the reflective layer 13b has light transmittance like a half mirror, a high refractive index layer, or a dielectric multilayer film, a light absorption layer may be provided on the back side of the reflective layer 13b. Thereby, the visibility of the visualized latent image can be enhanced. When the light absorption layer is provided, the light absorption layer may face the entire back surface of the reflection layer 13b, or may face only a part of the back surface of the reflection layer 13b. The light absorption layer can be formed by, for example, printing or coating.

  The cholesteric liquid crystal layer 19 includes liquid crystal molecules or mesogenic groups forming a helical structure. The helical axis of this helical structure is substantially perpendicular to the main surface of the cholesteric liquid crystal layer 19. Further, the helical pitch of this helical structure is equal to the wavelength of any light component of visible light. For example, the helical pitch is made substantially equal to a wavelength λ described later.

  The cholesteric liquid crystal layer 19 may have a single layer structure or a multilayer structure. In the latter case, the spiral pitch and / or the rotational direction of the spiral are made different between layers.

  The cholesteric liquid crystal layer 19 faces a part of the front surface of the reflective layer 13b. The cholesteric liquid crystal layer 19 has almost uniform optical characteristics in the plane.

  The cholesteric liquid crystal layer 19 may have an optical property distribution in the plane. For example, the cholesteric liquid crystal layer 19 may include a plurality of portions that are adjacent to each other in the in-plane direction and have different spiral pitches and / or spiral rotation directions. Alternatively, the cholesteric liquid crystal layer 19 may include a plurality of portions that are adjacent in the in-plane direction and have different layer structures.

  The cholesteric liquid crystal layer 19 may face the entire front surface of the reflective layer 13b. In this case, the cholesteric liquid crystal layer 19 may include a plurality of portions that are adjacent to each other in the in-plane direction and have different spiral pitches and / or spiral rotation directions. Alternatively, the cholesteric liquid crystal layer 19 may include a plurality of portions that are adjacent in the in-plane direction and have different layer structures.

  The cholesteric liquid crystal layer 19 is obtained, for example, by solidifying a liquid crystal material exhibiting a cholesteric phase. As the liquid crystal material, for example, a cholesteric liquid crystal compound can be used. Alternatively, a liquid crystal composition containing a nematic liquid crystal compound and a chiral agent and exhibiting a cholesteric phase may be used as the liquid crystal material.

  The cholesteric liquid crystal layer 19 is formed, for example, by forming a layer made of a liquid crystal material having a glass transition temperature sufficiently higher than the operating temperature range of the laminate 10 and applying heat, heat and pressure to this layer as necessary. Can be obtained. For example, the layer made of this liquid crystal material can be formed by applying an ink containing such a liquid crystal material. For the application of the ink, for example, screen printing or gravure printing can be used.

  The cholesteric liquid crystal layer 19 may be formed by other methods. For example, first, a film having a cholesteric phase and containing a crosslinkable liquid crystal material is formed. This film can be formed using, for example, screen printing or gravure printing. Next, crosslinking of the liquid crystal material is caused. Thereby, the cholesteric liquid crystal layer 19 can be obtained.

  When the liquid crystal material is used for the birefringent layer 12, the alignment film 17 is used to control the alignment of the mesogenic group. When the cholesteric liquid crystal layer 19 is formed on the birefringent layer 12, the alignment film 17 may face the cholesteric liquid crystal layer 19 with the birefringent layer 12 interposed therebetween. Alternatively, the alignment film 17 may be omitted.

  The alignment film 17 includes a first alignment portion 17a and a second alignment portion 17b that are adjacent to each other in the in-plane direction. Before the birefringent layer 12 is formed, the first alignment portion 17a and the second alignment portion 17b are subjected to alignment treatment using, for example, a photo alignment method or a rubbing method. The first alignment portion 17a and the second alignment portion 17b differ in the direction in which the mesogenic groups of the liquid crystal material are aligned (hereinafter referred to as the alignment direction).

  In the photo-alignment method, the film is irradiated with light having anisotropy such as polarized light to induce molecular rearrangement or chemical reaction in the film. For example, photoisomerization of azobenzene derivatives, photodimerization or crosslinking of derivatives such as cinnamic acid ester, coumarin, chalcone, and benzophenone, and photolysis of polyimide and the like are caused. Thereby, anisotropy is imparted to the film.

  In the rubbing method, polymer layers such as a polyimide layer and a polyvinyl alcohol layer are formed, and the surface is rubbed with a rubbing cloth. The mesogenic groups of the liquid crystal material are aligned in the direction rubbed with the rubbing cloth, that is, the rubbing direction.

  When utilizing the photo-alignment method, the alignment film 17 can be formed, for example, by the following method. First, a film made of the above material is formed. This film can be formed using, for example, a gravure coating method or a micro gravure coating method. A portion of the film is then exposed with linearly polarized light. Then, the other part of the previous film is exposed with linearly polarized light having a different polarization plane (vibration plane of the electric field vector). Thereby, the alignment film 17 including the first alignment portion 17a and the second alignment portion 17b having different alignment directions is obtained.

  When the photo-alignment method is used, the alignment film 17 can be formed by other methods. First, a film made of the above material is formed, and a part of the film is exposed with natural light from an oblique direction. Next, the light irradiation direction is rotated around the normal of the film surface, and the other part of the film is exposed with natural light from an oblique direction. Thereby, the alignment film 17 including the first alignment portion 17a and the second alignment portion 17b having different alignment directions is obtained.

  When the rubbing method is used, the alignment film 17 can be formed by the following method, for example. First, a polymer film is formed. The polymer film can be formed using, for example, a gravure coating method or a micro gravure coating method. Next, the entire surface of the polymer film is rubbed in one direction with a rubbing cloth. Next, a mask is placed on the polymer film, and this is rubbed in another direction with a rubbing cloth. Thereafter, by removing the mask from the polymer film, the alignment film 17 including the first alignment portion 17a and the second alignment portion 17b having different alignment directions can be obtained.

  The birefringent layer 12 includes a first birefringent portion 12a and a second birefringent portion 12b that are adjacent in the in-plane direction. The first birefringent portion 12a faces a part of the front surface of the cholesteric liquid crystal layer 19 and a part of the front surface of the reflective layer 13b. The second birefringent portion 12b faces the other part of the front surface of the cholesteric liquid crystal layer 19 and the other part of the front surface of the reflective layer 13b.

  The first birefringent portion 12a has substantially uniform optical characteristics in the plane. Similarly, the second birefringent portion 12b also has substantially uniform optical characteristics within the plane. Typically, the first birefringent portion 12a and the second birefringent portion 12b have the same optical characteristics.

  The first birefringent portion 12a and the second birefringent portion 12b have different slow axis directions. The angle formed by the slow axis of the first birefringent portion 12a and the slow axis of the second birefringent portion 12b is, for example, 45 ° or more, and usually 80 ° or more. Typically, the first birefringent portion 12a and the second birefringent portion 12b are arranged so that their slow axes are orthogonal to each other.

  Each of the first birefringent portion 12a and the second birefringent portion 12b has a retardation for light having a wavelength of λ of less than λ / 4. The wavelength λ is one wavelength in the visible light range, for example, the wavelength of green light, that is, a wavelength in the range of 500 nm to 600 nm. Typically, in each of the first birefringent portion 12a and the second birefringent portion 12b, the retardation for light having a wavelength λ of 550 nm is a value in the range of 3λ / 32 to 5λ / 32. Set. For example, in each of the first birefringent portion 12a and the second birefringent portion 12b, the retardation for light having a wavelength λ of 550 nm is set to λ / 8.

  The birefringent layer 12 may be in direct contact with the front surface of the cholesteric liquid crystal layer 19 and / or the front surface of the reflective layer 13b. Alternatively, an optically isotropic transparent layer may be interposed between the birefringent layer 12 and the cholesteric liquid crystal layer 19 and / or the reflective layer 13b.

  As the material of the first birefringent portion 12a and the second birefringent portion 12b, for example, a liquid crystal material can be used. As the liquid crystal material, for example, a liquid crystal material that is solid in a use temperature range of the laminate 10 and exhibits a nematic phase or a smectic phase, typically a thermotropic liquid crystal material or a polymer liquid crystal material can be used. . In this case, the birefringent layer 12 can be formed by the following method, for example.

  First, a thermotropic liquid crystal layer is formed on the alignment film 17. The thermotropic liquid crystal layer can be formed using, for example, a gravure coating method or a micro gravure coating method. Next, the thermotropic liquid crystal layer is heated to a temperature equal to or lower than the nematic-isotropic phase transition temperature (NI point). This facilitates a change in orientation of the mesogenic group. After the mesogenic groups are sufficiently aligned along the alignment directions above the first alignment portion 17a and the second alignment portion 17b, the thermotropic liquid crystal layer is cooled. Thereby, the birefringent layer 12 including the first birefringent portion 12a and the second birefringent portion 12b having different slow axis directions is obtained.

  Alternatively, a coating film containing a liquid crystal monomer having a reactive functional group is formed on the alignment film 17. This coating film can be formed using, for example, a gravure coating method or a micro gravure coating method. Next, the coating film is irradiated with an energy beam such as an electron beam or an ultraviolet ray. Alternatively, this coating film is heated. Thereby, a coating film is hardened. As described above, the birefringent layer 12 including the first birefringent portion 12a and the second birefringent portion 12b, each made of a polymer liquid crystal material and having different slow axis directions, is obtained.

  When the alignment film 17 has birefringence, a film formed by the method described for the alignment film 17 may be used as the birefringent layer 12 and the alignment film 17 may be omitted. Alternatively, a laminate of a film formed by the method described with respect to the alignment film 17 and a film formed by the method described with respect to the birefringent layer 12 may be used as the birefringent layer 12 and the alignment film 17 may be omitted. Good.

  A birefringent stretched film may be used as each of the first birefringent portion 12a and the second birefringent portion 12b. As this stretched film, for example, a uniaxially or biaxially stretched polyolefin film and polyester film can be used.

  FIG. 3 is a plan view schematically showing a modification of the identification laminate shown in FIGS. 1 and 2. FIG. 4 is a cross-sectional view taken along line IV-IV of the laminate shown in FIG. The identification laminate 10 has the same structure as the identification laminate 10 described with reference to FIGS. 1 and 2 except that the following structure is adopted.

  The laminated body 10 shown in FIGS. 3 and 4 further includes a diffractive structure forming layer 18 interposed between the base material 16 and the reflective layer 13b. The main surface of the diffractive structure forming layer 18 on the reflective layer 13b side includes a convex pattern or a concave pattern. The front surface of the reflective layer 13 b includes a convex pattern or a concave pattern corresponding to the convex pattern or the concave pattern of the diffractive structure forming layer 18. This convex pattern or concave pattern forms a hologram or a diffraction grating as a diffractive structure. This diffraction structure forms a diffraction image on the front surface of the laminate. FIG. 3 shows a diffraction image HG formed by holography as an example.

  The hologram can be formed by the following method, for example. First, a relief master plate composed of a fine convex pattern or a concave pattern is produced by using an optical photographing method. Next, by using an electroplating method, a nickel press plate in which a concave pattern or a convex pattern is duplicated from the master plate is produced. Thereafter, the press plate is pressed against the diffraction structure forming layer 18 while heating. Thereby, the convex pattern or the concave pattern is transferred to the diffractive structure forming layer 18. Further, the reflective layer 13 b is formed on the diffractive structure forming layer 18. As described above, a hologram can be formed.

The hologram can be formed by other methods. That is, first, the reflective layer 13 b is formed on the flat diffractive structure forming layer 18. Next, the press plate is pressed against the reflective layer 13b while heating. Thereby, a convex pattern or a concave pattern is transferred to the reflective layer 13b and the diffractive structure forming layer 18. As described above, a hologram can be formed.
This type of hologram is called a relief hologram.

  The diffraction grating can be formed by a method similar to that described for the hologram, except that no optical imaging method is used. In the case of forming a diffraction grating, an image called a grating image or a dot matrix (pixelgram or the like) may be displayed by arranging a plurality of pixels each including a diffraction grating.

  The diffraction structure forming layer 18 can be omitted. For example, when the above-described convex pattern or concave pattern can be formed on the surface of the substrate 16, the diffractive structure forming layer 18 is not necessary.

  This laminate 10 has the above-described diffraction structure. Therefore, the laminate 10 described with reference to FIGS. 3 and 4 is more difficult to counterfeit than the laminate 10 described with reference to FIGS. 1 and 2.

  Hereinafter, regions corresponding to the first birefringent portion 12a and the second birefringent portion 12b in the front surface of the laminate 10 described with reference to FIGS. 1 to 4 are referred to as regions A1 and A2, respectively. . Moreover, the area | region corresponding to the cholesteric liquid crystal layer 19 and the area | region other than that are called the area | region B1 and B2 among the front surfaces of this laminated body 10, respectively. Then, an overlapping portion between the region A1 and the region B1, an overlapping portion between the region A1 and the region B2, an overlapping portion between the region A2 and the region B1, and an overlapping portion between the region A2 and the region B2 are respectively referred to as regions A1B1 and A1B2. , A2B1, and A2B2.

  Each of the regions A1B1 and A1B2 forms a latent image that is difficult to distinguish from each other. That is, when the front surface of the laminate 10 is directly observed without using a polarizer, it is difficult to find the difference between the region A1B1 and the region A1B2. When the front surface of the laminated body 10 is observed through a polarizer such as a verification tool described later, a difference in brightness is generated between the region A1B1 and the region A1B2. Thereby, the latent image is visualized.

  Each of the areas A1B2 and A2B2 also forms a latent image that is difficult to distinguish from each other. That is, when the front surface of the laminate 10 is directly observed without using a polarizer, it is difficult to find the difference between the region A1B2 and the region A2B2. When the front surface of the laminated body 10 is observed through a polarizer such as a verification tool described later, a difference in brightness is generated between the region A1B2 and the region A2B2. Thereby, the latent image is visualized.

  The region B1 is a region corresponding to the cholesteric liquid crystal layer 19. Therefore, due to the selective reflection, the color of the region B <b> 1 may change according to the angle formed between the normal line of the main surface of the stacked body 10 and the line of sight. That is, a color shift can occur in the region B1. On the other hand, no color shift due to selective reflection can occur in the region B2.

  FIG. 5 is a plan view schematically showing an example of an image seen when the laminated body shown in FIGS. 3 and 4 is observed through the verification tool. FIG. 6 is a plan view schematically showing another example of an image seen when the laminated body shown in FIGS. 3 and 4 is observed through a verification tool. The state shown in FIG. 6 corresponds to the state in which the verification tool 200 is rotated by 90 ° around the normal from the state shown in FIG.

  In FIG. 5 and FIG. 6, the following conditions are assumed as an example. Each of the first birefringent portion 12a and the second birefringent portion 12b is a λ / 8 wavelength plate. That is, each of the first birefringent portion 12a and the second birefringent portion 12b has a polarization plane when the plane of polarization is oblique to the slow axis and linearly polarized light having a wavelength of λ is incident. Emits first linearly polarized light parallel to the fast axis and second linearly polarized light whose plane of polarization is parallel to the slow axis and whose phase is delayed by λ / 8 with respect to the first linearly polarized light. Moreover, in this laminated body 10, the angle which the slow axis of the 1st birefringent part 12a and the slow axis of the 2nd birefringent part 12b make is 90 degrees. Further, the cholesteric liquid crystal layer 19 exhibits the maximum reflectance with respect to left circularly polarized light having a wavelength of λ among right circularly polarized light and left circularly polarized light incident perpendicularly to the main surface. A left elliptical polarizer is used as the verification tool 200.

In the example shown in FIG. 5, the areas A1B2 and A2B1 appear as bright parts, the area A2B2 appears as dark parts, and the area A1B1 appears darker than the areas A1B2 and A2B1 and brighter than the area A2B2. On the other hand, in the example shown in FIG. 6, the regions A1B1 and A2B2 appear as bright portions, the region A1B2 appears as a dark portion, the region A2B1 appears darker than the regions A1B1 and A2B2, and appears lighter than the region A1B2. As a result of such a brightness difference, the observer can perceive the latent image formed by these regions as a visible image.
Next, the reason why the above-described brightness difference occurs will be described.
7 to 10 are diagrams schematically illustrating an example of a method for visualizing the latent image held by the stacked body illustrated in FIGS. 3 and 4. FIG. 7 illustrates a state in which the region A1B1 reflects light. FIG. 8 illustrates a state where the region A1B2 reflects light. FIG. 9 illustrates a state where the region A2B1 reflects light. FIG. 10 illustrates a state where the region A2B2 reflects light.

The laminate 10 shown in FIGS. 7 to 10 has the same structure as the laminate 10 described with reference to FIGS. 5 and 6. That is, each of the first birefringent portion 12a and the second birefringent portion 12b is a λ / 8 wavelength plate. In other words, each of the first birefringent portion 12a and the second birefringent portion 12b, when the plane of polarization and wavelength are oblique with respect to the slow axis A _S is made incident linearly polarized light of λ In addition, the first linearly polarized light whose polarization plane is parallel to the fast axis A _F, and the second whose polarization plane is parallel to the slow axis A _S and whose phase is delayed by λ / 8 with respect to the first linearly polarized light. Emits linearly polarized light. In the laminated body 10, the angle formed by the slow axis A _{S of} the first birefringent portion 12a and the slow axis A _S of the second birefringent portion 12b is 90 °. Further, the cholesteric liquid crystal layer 19 exhibits the maximum reflectance with respect to left circularly polarized light having a wavelength of λ among right circularly polarized light and left circularly polarized light incident perpendicularly to the main surface. Here, for the sake of simplicity, the reflectance of the cholesteric liquid crystal layer 19 for left-handed circularly polarized light having a wavelength of λ is 100%.

  In the method shown in FIGS. 7 to 10, the light from the light source 300 is transmitted through the verification tool 200 and the transmitted light is irradiated to the front surface of the laminate 10. And the reflected light from the laminated body 10 is permeate | transmitted to the verification tool 200, and the observer 400 observes this transmitted light.

Here, the verification tool 200 will be described.
The verification tool 200 includes a linear polarizer 201 and a birefringent layer 202. The birefringent layer 202 faces one of the light incident surfaces of the linear polarizer 201.

  The linear polarizer 201 is, for example, an absorptive polarizing layer. As the absorption polarizing layer, for example, a polarizing layer obtained by impregnating a stretched polyvinyl alcohol layer with iodine can be used. The linear polarizer 201 may not be a polarizing layer. For example, a polarizing prism may be used as the linear polarizer 201.

  The birefringent layer 202 has a retardation of less than λ / 4 at the previous wavelength λ. The sum of the retardation at the wavelength λ of the birefringent layer 202 and the retardation at the wavelength λ of the first birefringent portion 12a is approximately λ / 4, and the retardation of the birefringent layer 202 at the wavelength λ is approximately λ / 4. And the retardation at the wavelength λ of the second birefringent portion 12b is approximately λ / 4. Typically, the retardation for light having a wavelength λ of 550 nm of the birefringent layer 202 is set to a value in the range of 3λ / 32 to 5λ / 32. For example, the retardation for light having a wavelength λ of the birefringent layer 202 of 550 nm is set to λ / 8. As the birefringent layer 202, for example, those exemplified for the first birefringent portion 12a and the second birefringent portion 12b can be used.

The linear polarizer 201 and the birefringent layer 202 are such that the slow axis A _S ′ and the fast axis A _F ′ of the birefringent layer 202 are oblique to the polarization plane of the linearly polarized light transmitted through the linear polarizer 201. Arrange so that The angle formed between the slow axis A _S ′ of the birefringent layer 202 and the polarization plane of the linearly polarized light transmitted through the linear polarizer 201 is, for example, in the range of 40 ° to 50 °, and typically 45 °. .

In the methods of FIGS. 7 to 10, the following configuration is adopted for the verification tool 200 as an example. That is, an absorptive polarizing layer is used as the linear polarizer 201, and a λ / 8 wavelength plate is used as the birefringent layer 202. The angle formed by the transmission axis A _T ′ of the linear polarizer 201 and the slow axis A _S ′ of the birefringent layer 202 is 45 °.

7 to 10, the stacked body 10 and the verification tool 200 are arranged such that the linear polarizer 201 faces the light source 300 and the observer 400 and the birefringent layer 202 faces the stacked body 10. Yes. Here, as an example, a 'is perpendicular to the slow axis A _S between the first birefringent portion 12a, the slow axis A _S of the birefringent layer 202' slow axis A _S of the birefringent layer 202 The slow axis A _{S of} the second birefringent portion 12b is made parallel. In addition, in this method, the laminated body 10, the light source 300, and the observer 400 are arranged so that the observer 400 can observe the reflected light when the laminated body 10 specularly reflects light from the light source 300. .

  When the front surface of the laminated body 10 is observed without using the verification tool 200, all of the regions A1B1, A1B2, A2B1, and A2B2 appear as bright portions, and there is almost no difference in brightness between them. However, as described above, the areas A1B1 and A2B1 cause a color shift, whereas the areas A1B2 and A2B2 do not cause a color shift. Therefore, in this case, it is extremely difficult to find the difference between the region A1B1 and the region A2B1 and the difference between the region A1B2 and the region A2B2. In addition, in this case, it is possible to find a difference between the region B1 and the region B2, but there is no significant difference in how they are seen.

When the front surface of the stacked body 10 is observed using the verification tool 200, the light emitted from the light source 300, for example, natural light L _N , is applied to the linear polarizer 201 of the verification tool 00 as shown in FIGS. 7 to 10. Make it incident. Here, for simplification, it is assumed that the light source 300 emits only light having a wavelength of λ. Linear polarizer 201, of the natural light L _N, polarization plane 'is transmitted through the first linearly polarized light L _L1 parallel to, the plane of polarization transmission axis A _T' transmission axis A _T second perpendicular Absorbs linearly polarized light L _L2 .

The first linearly polarized light L _L1 emitted from the linear polarizer 201 enters the birefringent layer 202. The birefringent layer 202 converts the first linearly polarized light L _L1 into the first right elliptically polarized light L _RE1 . When the first right elliptically polarized light L _RE1 is viewed from the reflective layer 13 b side, the major axis of the ellipse formed by the locus of the end of the electric field vector is relative to the slow axis A _S ′ of the birefringent layer 202. Tilt 45 ° counterclockwise.

The first right elliptically polarized light L _RE1 emitted from the birefringent layer 202 is incident on the first birefringent portion 12a as shown in FIG. 7 in the portion corresponding to the region A1B1. The first birefringent portion 12a converts the first right elliptically polarized light L _RE1 into the first linearly polarized light L _L1 .

The first linearly polarized light L _L1 emitted from the first birefringent portion 12 a enters the cholesteric liquid crystal layer 19. The cholesteric liquid crystal layer 19, of the first linear polarized light L _L1, is transmitted through the right circularly polarized light L _RC, selectively reflects left-circularly polarized light L _LC. Here, a process in which a light component transmitted through the cholesteric liquid crystal layer 19 reaches the observer 400 will be described first, and then a process in which a light component reflected by the cholesteric liquid crystal layer 19 reaches the observer 400 will be described. To do.

The right circularly polarized light L _RC transmitted through the cholesteric liquid crystal layer 19 is reflected by the reflective layer 13b. As a result, the right circularly polarized light L _RC is converted into left circularly polarized light L _LC . The left circularly polarized light L _LC is selectively reflected by the cholesteric liquid crystal layer 19 and then reflected by the reflective layer 13b. As a result, the left circularly polarized light L _LC is converted to the right circularly polarized light L _RC . The right circularly polarized light L _RC is transmitted through the cholesteric liquid crystal layer 19.

The right circularly polarized light L _RC emitted from the cholesteric liquid crystal layer 19 is incident on the first birefringent portion 12a. The first birefringent portion 12a converts the right circularly polarized light _LRC into the second right elliptically polarized light _LRE2 . When the second right elliptically polarized light L _RE2 is viewed from the viewer 400 side, the major axis of the ellipse formed by the locus of the end of the electric field vector is relative to the slow axis A _{S of} the first birefringent portion 12a. Tilted 45 ° clockwise.

The second right elliptically polarized light L _RE2 emitted from the first birefringent portion 12 a enters the birefringent layer 202. The birefringent layer 202 converts the second right elliptically polarized light L _RE2 into the right circularly polarized light L _RC .

The right circularly polarized light L _RC emitted from the birefringent layer 202 is incident on the linear polarizer 201. The linear polarizer 201 transmits the first linearly polarized light L _L1 of the right circularly polarized light L _RC and absorbs the second linearly polarized light L _L2 having a polarization plane perpendicular to the polarization plane.

The left circularly polarized light L _LC selectively reflected by the cholesteric liquid crystal layer 19 without passing through the cholesteric liquid crystal layer 19 is incident on the first birefringent portion 12a. The first birefringent portion 12a converts the left circularly polarized light _LLC into the first left elliptically polarized light _LLE1 . When the first left elliptical polarized light L _LE1 is viewed from the viewer 400 side, the major axis of the ellipse formed by the locus of the end of the electric field vector is relative to the slow axis A _{S of} the first birefringent portion 12a. Tilted 45 ° counterclockwise.

The first left elliptical polarized light L _LE1 emitted from the first birefringent portion 12 a enters the birefringent layer 202. The birefringent layer 202 converts the first left elliptically polarized light L _LE1 into the left circularly polarized light L _LC .

The left circularly polarized light L _LC emitted from the birefringent layer 202 is incident on the linear polarizer 201. The linear polarizer 201 transmits the first linearly polarized light L _L1 out of the left circularly polarized light L _LC and absorbs the second linearly polarized light L _L2 having a polarization plane perpendicular to the polarization plane.

  Thus, the reflected light from the region A1B1 is elliptically polarized light, and this elliptically polarized light is converted into circularly polarized light by the birefringent layer 202. Therefore, the verification tool 200 ideally absorbs half of the reflected light from the region A1B1 and emits the other half toward the viewer 400.

In the portion corresponding to the region A1B2, the first right elliptically polarized light L _RE1 emitted from the verification tool 200 enters the first birefringent portion 12a as shown in FIG. The first birefringent portion 12a converts the first right elliptically polarized light L _RE1 into the first linearly polarized light L _L1 .

The first linearly polarized light L _L1 emitted from the first birefringent portion 12a is reflected by the reflective layer 13b and reenters the first birefringent portion 12a. The first birefringent portion 12a converts the first linearly polarized light L _L1 into the first right elliptically polarized light L _RE1 .

The first right elliptically polarized light L _RE1 emitted from the first birefringent portion 12 a enters the birefringent layer 202. The birefringent layer 202 converts the first right elliptically polarized light L _RE1 into the first linearly polarized light L _L1 .

The first linearly polarized light L _L1 emitted from the birefringent layer 202 enters the linear polarizer 201. The linear polarizer 201 ideally transmits the first linearly polarized light L _L1 without absorbing it. That is, the verification tool 200 ideally emits all of the reflected light from the region A1B2 toward the observer 400.

In the portion corresponding to the region A2B1, the first right elliptically polarized light L _RE1 emitted from the verification tool 200 is incident on the second birefringent portion 12b as shown in FIG. Second birefringent portion 12b converts the second right elliptically polarized light L _RE2 to right circularly polarized light L _RC.

The right circularly polarized light L _RC emitted from the second birefringent portion 12 b enters the cholesteric liquid crystal layer 19. The cholesteric liquid crystal layer 19 transmits the right circularly polarized light _LRC .

The right circularly polarized light L _RC transmitted through the cholesteric liquid crystal layer 19 is reflected by the reflective layer 13b. As a result, the right circularly polarized light L _RC is converted into left circularly polarized light L _LC . The left circularly polarized light L _LC is selectively reflected by the cholesteric liquid crystal layer 19 and then reflected by the reflective layer 13b. As a result, the left circularly polarized light L _LC is converted to the right circularly polarized light L _RC . The right circularly polarized light L _RC is transmitted through the cholesteric liquid crystal layer 19.

The right circularly polarized light L _RC emitted from the cholesteric liquid crystal layer 19 is incident on the second birefringent portion 12b. The second birefringent portion 12b converts the right circularly polarized light _LRC into the first right elliptically polarized light _LRE1 .

The first right elliptically polarized light L _RE1 emitted from the second birefringent portion 12 b enters the birefringent layer 202. The birefringent layer 202 converts the first right elliptically polarized light L _RE1 into the first linearly polarized light L _L1 .

The first linearly polarized light L _L1 emitted from the birefringent layer 202 enters the linear polarizer 201. The linear polarizer 201 ideally transmits the first linearly polarized light L _L1 without absorbing it. That is, the verification tool 200 ideally emits all the reflected light from the region A2B1 toward the observer 400.

In the portion corresponding to the region A2B2, the first right elliptically polarized light L _RE1 emitted from the verification tool 200 is incident on the second birefringent portion 12b as shown in FIG. The second birefringent portion 12b converts the first right elliptically polarized light L _RE1 into the right circularly polarized light L _RC .

Right circularly polarized light L _RC emitted from the second birefringent portion 12b is reflected by the reflection layer 13b. As a result, the right circularly polarized light L _RC is converted into left circularly polarized light L _LC .

The left circularly polarized light L _LC from the reflective layer 13b is incident on the second birefringent portion 12b. The second birefringent portion 12b converts the left circularly polarized light _LLC into the second left elliptically polarized light _LLE2 . When the second left elliptical polarized light L _LE2 is viewed from the viewer 400 side, the major axis of the ellipse formed by the locus of the end of the electric field vector is relative to the slow axis A _{S of} the first birefringent portion 12a. Tilted 45 ° counterclockwise.

The second left elliptically polarized light L _LE2 emitted from the second birefringent portion 12 b enters the birefringent layer 202. The birefringent layer 202 converts the second left elliptically polarized light L _LE2 into the second linearly polarized light L _L2 .

The second linearly polarized light L _L2 emitted from the birefringent layer 202 enters the linear polarizer 201. The linear polarizer 201 ideally absorbs the second linearly polarized light L _L2 without transmitting it. That is, the verification tool 200 ideally absorbs all of the reflected light from the region A2B2.

  Thus, the verification tool 200 transmits only part of the reflected light from the region A1B1, transmits substantially all of the reflected light from the regions A1B2 and A2B1, and absorbs almost all of the reflected light from the region A2B2. . Accordingly, the viewer 400 perceives the areas A1B2 and A2B1 as bright parts, perceives the area A2B2 as dark parts, and perceives the area A1B1 as darker than the bright parts and brighter than the dark parts. . That is, by using the verification tool 200, the latent image can be visualized as shown in FIG.

  When the verification tool 200 is rotated by 90 ° around the light beam, the positions of the intermediate portion and the bright portion are switched between the region A1B1 and the region A2B1, and the bright portion and the dark portion are changed between the region A1B2 and the region A2B2. The position of will change. Therefore, in this case, the viewer 400 perceives the visible image shown in FIG.

  As described above, in this technique, the retardation that is insufficient due to the thinning of the birefringent layer 12 of the stacked body 10 is compensated by the birefringent layer 202 of the verification tool 200. This prevents a decrease in contrast ratio associated with making the birefringent layer 12 of the laminate 10 thinner. That is, according to this technique, the birefringent layer 12 of the laminate 10 can be made thin without impairing the visibility of the visualized latent image.

  The laminate 10 described above is supported directly or indirectly on an article whose authenticity is to be confirmed. And when discriminating an article whose authenticity is unknown between a genuine product and a non-authentic product such as a counterfeit product, the laminate 10 can be used as described below.

  As described above, the stacked body 10 includes the reflective layer 13b. Therefore, the article on which the laminate 10 is supported has a light reflective region. Therefore, when an article whose authenticity is unknown does not have a light-reflective region, it can be determined that the article is non-authentic.

  In addition, the stacked body 10 has a latent image that is visualized by being observed through the verification tool 200. That is, at least a partial region of the article supporting the laminated body 10 has a latent image that is visualized by being observed through the verification tool 200. Therefore, if an article with unknown authenticity does not have such a latent image, it can be determined that the article is non-authentic.

  The latent image is formed on the reflective layer 13b. Therefore, even if an article with an unknown authenticity includes a light-reflective area and an area having a latent image, it is determined that the article is non-authentic if the areas are not identical. can do.

  If an article of unknown authenticity holds the previous latent image, the shape and / or size of the visualized latent image may be compared with that of the authentic product. If the shape and / or size of the visualized latent image is different from that of the genuine product, it can be determined that the article is non-genuine.

  If an article with an unknown authenticity holds the previous latent image, the contrast ratio of the visualized latent image is used to distinguish an article with an unknown authenticity between genuine and non-authentic. Also good.

  In the above-described technique, when both the retardation of the birefringent layer 12 included in the laminate 10 and the retardation of the birefringent layer 202 included in the verification tool 200 are both set to λ / 8, the visualized latent image is displayed. The contrast ratio can be maximized. For example, when such a design is adopted, even if a non-genuine product retains the previous latent image, unless the retardation of the birefringent layer is set to λ / 8, The contrast ratio of the visualized latent image is less than that of the genuine product.

  Therefore, for example, the contrast ratio of the visualized latent image may be compared with that of the genuine product. If the contrast ratio of the visualized latent image is different from that of the genuine product, it can be determined that the article is non-genuine.

  Alternatively, the latent image may be visualized using a plurality of verification tools 200 having different retardations of the birefringent layer 202 or using a verification tool 200 including a plurality of birefringent layers 202 having different retardations. Good. For example, the birefringent layer 202 employs a structure in which a portion with retardation λ / 8 and a portion with λ / 4 are adjacent in the in-plane direction. Then, the birefringent layer 202 is opposed to only a part of the light incident surface of the linear polarizer 201. That is, the verification tool 200 is given a function as a linear polarizer, an elliptical polarizer, and a circular polarizer. If the contrast ratio of the latent image visualized using a linear or circular polarizer is greater than the contrast ratio of the image visualized using an elliptical polarizer, the article is judged to be non-genuine. be able to.

  For the determination of an article, only one of the above-described methods may be used, or a plurality of methods may be used in combination. This technique may be combined with other determination techniques. For example, a color shift caused by the cholesteric liquid crystal layer 19 and / or a determination technique using the diffraction image HG described with reference to FIGS. 3 and 4 may be used. Increasing the number of methods used to determine an article decreases the probability of erroneously determining a non-authentic product as a genuine product.

  Next, the second aspect of the present invention will be described. The second mode is the same as the first mode except that the following configuration is adopted for the laminate 10.

  FIG. 11 is a cross-sectional view schematically showing the identification laminate according to the second aspect of the present invention. The identification laminate 10 further includes a light absorption layer 13a interposed between the reflective layer 13b and the cholesteric liquid crystal layer 19, and the laminate 10 described with reference to FIGS. It is the same.

  The light absorbing layer 13a may be a black layer, or may be a layer that absorbs only part of visible light and reflects the other part. Here, as an example, it is assumed that the light absorption layer 13a is a black layer.

  The light absorption layer 13a is obtained, for example, by applying an ink containing a pigment and / or a dye and a resin to the front surface of the reflection layer 13b. In addition, you may abbreviate | omit the part interposed between the light absorption layer 13a and the base material 16 among the reflection layers 13b.

  When this structure is adopted, when the laminated body 10 is observed without using the verification tool 200, the region B1 looks darker than the region B2. Further, when this structure is adopted, the color shift of the region B1 due to selective reflection becomes large. Therefore, it is easy to determine an article using a color shift. Furthermore, when the laminated body 10 of FIG. 11 is observed through the verification tool 200, an image different from that described with reference to FIGS.

  FIG. 12 is a plan view schematically showing an example of an image seen when the laminated body shown in FIG. 11 is observed through the verification tool. FIG. 13 is a plan view schematically showing another example of an image seen when the laminated body shown in FIG. 11 is observed through the verification tool. Note that the state shown in FIG. 13 corresponds to the state in which the verification tool 200 is rotated by 90 ° around the normal from the state shown in FIG.

  In FIG. 12 and FIG. 13, the following conditions are assumed as an example. Each of the first birefringent portion 12a and the second birefringent portion 12b is a λ / 8 wavelength plate. That is, each of the first birefringent portion 12a and the second birefringent portion 12b has a polarization plane when the plane of polarization is oblique to the slow axis and linearly polarized light having a wavelength of λ is incident. Emits first linearly polarized light parallel to the fast axis and second linearly polarized light whose plane of polarization is parallel to the slow axis and whose phase is delayed by λ / 8 with respect to the first linearly polarized light. Moreover, in this laminated body 10, the angle which the slow axis of the 1st birefringent part 12a and the slow axis of the 2nd birefringent part 12b make is 90 degrees. Further, the cholesteric liquid crystal layer 19 exhibits the maximum reflectance with respect to left circularly polarized light having a wavelength of λ among right circularly polarized light and left circularly polarized light incident perpendicularly to the main surface. A left elliptical polarizer is used as the verification tool 200.

  In the example shown in FIG. 12, the area A1B2 appears as a bright part, the areas A2B1 and A2B2 appear as dark parts, the area A1B1 appears darker than the area A1B2 and brighter than the areas A2B1 and A2B2. On the other hand, in the example shown in FIG. 13, the areas A1B1 and A1B2 appear as dark parts, the area A2B2 appears as bright parts, the area A2B1 appears brighter than the areas A1B1 and A1B2, and darker than the area A2B2. As a result of such a brightness difference, the observer can perceive the latent image formed by these regions as a visible image.

  The laminate 10 may include the diffractive structure described in the first aspect. In this case, the laminate 10 may further include the diffractive structure forming layer 18 described with reference to FIGS. 3 and 4. However, when the diffractive structure is provided in the reflective layer 13b, the diffracted image HG shown in FIG. 3 cannot be formed at the position where the light absorbing layer 13a and the diffractive structure face each other.

  The laminate 10 according to the first and second aspects can be used in various forms. Hereinafter, the use of the laminate shown in FIGS. 1 and 2 is used, but the laminate 10 shown in FIGS. 3 and 4 and the laminate 10 shown in FIG. 11 can also be used for the same use.

  FIG. 14 is a cross-sectional view schematically showing an example of an adhesive label including the laminate shown in FIGS. 1 and 2. The pressure-sensitive adhesive label 20 includes a laminate 10 and a pressure-sensitive adhesive layer 21 provided on the back surface thereof. For example, the adhesive label 20 is attached to an article whose authenticity is to be confirmed, or is attached to another article such as a tag to be attached to the article. If it carries out like this, the authenticity of goods can be confirmed by the method mentioned above.

  The adhesive label 20 may be brittle. Such an adhesive label 20 is obtained, for example, by forming a cutout and / or a perforation in the laminate 10. When the pressure-sensitive adhesive label 20 is brittle, the laminate 10 is easily broken when the pressure-sensitive adhesive label attached to an article whose authenticity is to be confirmed is peeled off. Therefore, it becomes difficult to replace the adhesive label 20.

  FIG. 15 is a cross-sectional view schematically showing an example of a recording medium including the laminate shown in FIGS. 1 and 2. The recording medium 30 includes a paper 31 and a laminated body 10 embedded therein. An opening is provided in a portion of the paper 31 that covers the front surface of the laminate 10. Thereby, the visibility of the visualized latent image is enhanced. If the latent image can be visualized, the paper 31 does not have to be provided with the previous opening.

  The recording medium 30 can be used as a sheet for an authentication medium such as a cash card, a credit card and a passport, or a securities medium such as a gift certificate and a stock certificate, for example. Alternatively, the recording medium 30 can be used as a part of an adhesive label described later. Alternatively, the recording medium 30 can be used as a tag or a part thereof to be attached to an article whose authenticity is to be confirmed. Alternatively, the recording medium 30 can be used as a package or a part thereof for containing an article whose authenticity is to be confirmed.

  The recording medium 30 is obtained, for example, by sandwiching the laminate 10 between fiber layers during papermaking. The recording medium 30 obtained by such a method is difficult to forge.

  16 is a cross-sectional view schematically showing an example of an adhesive label including the recording medium of FIG. The adhesive label 40 includes a recording medium 30 and an adhesive layer 41 provided on the back surface thereof. For example, the adhesive label 40 is attached to an article whose authenticity is to be confirmed, or is attached to another article such as a base material of a tag to be attached to the article.

  FIG. 17 is a cross-sectional view schematically showing an example of a transfer foil using a laminate having a structure similar to that shown in FIGS. 1 and 2.

  The transfer foil 50 includes a base material 52, an anti-counterfeit laminate 10, and an adhesive layer 51. The base material 52 supports the front surface of the laminate 10 so as to be peelable. The adhesive layer 51 is supported on the back surface of the laminate 10.

  The base material 52 is, for example, a resin film, paper, or a composite material containing them. As the material of the resin film, for example, the materials exemplified for the base material 16 can be used.

  The stacked body 10 includes an alignment film 17, a birefringent layer 12, a cholesteric liquid crystal layer 19, and a reflective layer 13 b that are stacked on a base material 52. The alignment film 17, the birefringent layer 12, the cholesteric liquid crystal layer 19, and the reflective layer 13 b are sequentially formed on the substrate 52. Each component included in the laminate 10 is the same as that described with reference to FIGS. 1 and 2.

  When the laminate of the birefringent layer 12, the cholesteric liquid crystal layer 19 and the reflective layer 13b is peeled off from the substrate 10, the alignment film 17 remains on the substrate 52 or the alignment film 17 is coherently broken. If it occurs, the alignment film 17 is not considered part of the laminate 10. Further, the alignment film 17 can be omitted.

  A release layer may be interposed between the substrate 52 and the laminate 10. As the material for the release layer, for example, acrylic resin, styrene resin, and nitrified cotton can be used. The release layer can be formed using, for example, a gravure coating method or a micro gravure coating method. The front surface of the reflective layer 13b may include the diffractive structure described with reference to FIGS.

  The adhesive layer 51 is made of, for example, a thermoplastic resin. As this thermoplastic resin, for example, a vinyl chloride vinyl acetate copolymer can be used.

  This transfer foil 50 is used as follows, for example. First, the transfer foil 50 is bonded to the transfer target using, for example, a roll transfer machine or a hot stamp. Next, the base material 52 is peeled from the laminate 10. Thereby, the laminated body 10 can be affixed on a to-be-transferred body.

  Many of the birefringent layers 12 made of a thermotropic liquid crystal material or a polymer liquid crystal material are tougher than the same thickness layers made of other polymer materials. Therefore, in particular, when the birefringent layer 12 is made of a thermotropic liquid crystal material or a polymer liquid crystal material and is thick, workability may be impaired. For example, burrs may occur when the laminate 10 is peeled off from the substrate 52. If the birefringent layer 12 is thin, high workability can be achieved.

  FIG. 18 is a cross-sectional view schematically illustrating an example of a labeled article including a forgery-preventing laminate. This labeled article 100 includes an article 101 and the laminate 10 described above.

  The article 101 is an article whose authenticity is to be confirmed. The article 101 is, for example, an authentication medium such as a cash card, a credit card, and a passport, or a securities medium such as a gift certificate and a stock certificate. The article 101 may be an article other than the authentication medium and the securities medium. For example, the article 101 may be a craft or a work of art. Alternatively, the article 101 may be a packaged product including a package and contents contained therein.

  The laminate 10 is supported by the article 101. For example, the laminate 10 is attached to the article 101. In this case, for example, the laminate 10 can be supported by the article 101 by attaching the adhesive label 20 shown in FIG. 14 or the adhesive label 40 shown in FIG. 16 to the article 101. Alternatively, the laminate 10 may be supported by the article 101 using the transfer foil 50 shown in FIG.

The laminate 10 may be supported on the article 101 by other methods.
For example, when the article 101 includes paper, the laminate 10 may be embedded in the paper. In this case, the labeled article 100 is obtained, for example, by sandwiching the laminate 10 between fiber layers during papermaking, and then performing printing or the like on the paper as necessary. In order to facilitate visualization of the latent image, an opening may be provided in a portion of the paper covering the front surface of the laminate 10. Moreover, there is no restriction | limiting in particular in the shape of the laminated body 10 embedded in paper. For example, the thread-like laminate 10 may be embedded in paper.

  The laminate 10 may be supported by the article 101 by attaching a tag including the laminate 10 to the article 101. If it is difficult for a general user to replace the tag on the article 101, the laminate 10 is sufficiently useful for confirming the authenticity of the article 101.

  Each of the laminate 10, the adhesive label 20, the recording medium 30, the adhesive label 40, the transfer foil 50, and the verification tool 200 may be distributed alone, or the discrimination method described above is described. A user manual may be attached and distributed. Alternatively, a security kit including the verification tool 200 and at least one of the laminate 10, the adhesive label 20, the recording medium 30, the adhesive label 40, and the transfer foil 50 may be distributed. The above-mentioned instruction manual can be attached to this security kit.

Examples of the present invention will be described below.
By a gravure coating method, a photo-alignment agent IA-01 manufactured by Dainippon Ink Industries, Ltd. was applied to a thickness of 0.1 μm on a polyethylene terephthalate substrate having a thickness of 16 μm. Next, the entire surface of this coating film was exposed with an illuminance of 1.0 J / cm ² using linearly polarized light having a wavelength of 365 nm. Thereafter, the above-mentioned coating film was subjected to pattern exposure at an illuminance of 2.0 J / cm ² using linearly polarized light having a wavelength of 365 nm. A photomask was used for this pattern exposure. The linearly polarized light was irradiated so that the plane of polarization was perpendicular to the plane of polarization of the linearly polarized light used for the entire exposure. As described above, an alignment film including first and second alignment portions having different alignment directions was obtained.

Next, an ultraviolet curable liquid crystal UCL-008 made by Dainippon Ink Manufacturing Co., Ltd. was printed on the alignment film by a microgravure coating method. After heating at 65 ° C. for 60 seconds, this coating film was exposed to ultraviolet light at an illuminance of 0.5 J / cm ^{2 in} a nitrogen atmosphere to cure the coating film. As a result, a birefringent layer including first and second birefringent portions whose slow axis directions differ by 90 ° was obtained. The thickness of the birefringent layer was 0.4 μm, and the difference Δn between the ordinary light refractive index and the extraordinary light refractive index in each of the first and second birefringent portions was 0.18. That is, each of the first and second birefringent portions is a λ / 8 wavelength plate that transmits a pair of linearly polarized light having a wavelength λ of 550 nm and gives a phase difference of λ / 8 to the linearly polarized light.

  Thereafter, a printing pattern containing a cholesteric liquid crystal pigment was formed on the birefringent layer by a screen printing method. As the cholesteric liquid crystal pigment, () made by () was used. In the cholesteric liquid crystal layer thus obtained, the mesogenic group formed a counterclockwise helical structure, and the helical pitch was about 550 nm.

  Next, an ink containing a black pigment was printed on the cholesteric liquid crystal layer by a screen printing method to form a light absorption layer.

  Next, a coating liquid containing acrylic polyol and isocyanate was coated on the birefringent layer and the light absorbing layer to form a diffraction structure forming layer having a thickness of 1.0 μm. The diffractive structure was transferred to the diffractive structure forming layer by hot embossing.

  Next, an aluminum reflective layer having a thickness of 50 nm was formed on the diffractive structure forming layer by vapor deposition. Further, an adhesive layer having a thickness of 2 μm made of a vinyl chloride vinyl acetate copolymer was formed on the reflective layer by a gravure coating method. As described above, a transfer foil was obtained.

  This transfer foil and paper were arranged so that the adhesive layer faced the paper, and the transfer foil was adhered to the paper by hot stamping. Next, the polyethylene terephthalate substrate was peeled from the birefringent layer. As described above, the laminate including the birefringent layer and the reflective layer was transferred from the base material to the paper.

  This laminate was observed without using a verification tool. As a result, the first birefringent portion and the second birefringent portion could not be distinguished.

  Next, this laminate was observed using a verification tool. As a verification tool, an absorptive polarizing film and a λ / 8 wave plate are attached via an acrylic adhesive so that the transmission axis of the polarizing film and the slow axis of the wave plate form an angle of 45 °. The combined ones were used. As a result, the region corresponding to the first birefringent portion and the region corresponding to the second birefringent portion could be viewed as a dark portion and a bright portion, respectively. That is, the latent image could be visualized.

  The verifier was then rotated 90 ° around the beam. When the laminate was observed through the verification tool in this state, the region corresponding to the first birefringent portion and the region corresponding to the second birefringent portion could be viewed as a bright portion and a dark portion, respectively. It was.

The top view which shows roughly the laminated body for identification which concerns on 1 aspect of this invention. Sectional drawing along the II-II line of the laminated body shown in FIG. The top view which shows roughly the modification of the laminated body for identification shown in FIG.1 and FIG.2. Sectional drawing along the IV-IV line of the laminated body shown in FIG. The top view which shows roughly an example of the image seen when the laminated body shown in FIG.3 and FIG.4 is observed through a verification tool. The top view which shows roughly the other example of the image seen when observing the laminated body shown in FIG.3 and FIG.4 through a verification tool. The figure which shows schematically an example of the method of visualizing the latent image which the laminated body shown in FIG.3 and FIG.4 hold | maintains. The figure which shows schematically an example of the method of visualizing the latent image which the laminated body shown in FIG.3 and FIG.4 hold | maintains. The figure which shows schematically an example of the method of visualizing the latent image which the laminated body shown in FIG.3 and FIG.4 hold | maintains. The figure which shows schematically an example of the method of visualizing the latent image which the laminated body shown in FIG.3 and FIG.4 hold | maintains. Sectional drawing which shows schematically the laminated body for identification which concerns on the 2nd aspect of this invention. The top view which shows roughly an example of the image seen when the laminated body shown in FIG. 11 is observed through a verification tool. The top view which shows roughly the other example of the image seen when the laminated body shown in FIG. 11 is observed through a verification tool. Sectional drawing which shows schematically an example of the adhesive label containing the laminated body shown in FIG.1 and FIG.2. FIG. 3 is a cross-sectional view schematically showing an example of a recording medium including the laminate shown in FIGS. 1 and 2. Sectional drawing which shows schematically an example of the adhesive label containing the recording medium of FIG. Sectional drawing which shows schematically an example of the transfer foil using the laminated body which has a structure similar to what was shown in FIG.1 and FIG.2. Sectional drawing which shows roughly an example of the labeled article containing the laminated body for forgery prevention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Laminate for identification, 12 ... Birefringent layer, 12a ... 1st birefringent part, 12b ... 2nd birefringent part, 13a ... Light absorption layer, 13b ... Reflective layer, 16 ... Base material, 17 ... Alignment film, 17a ... first alignment portion, 17b ... second alignment portion, 18 ... diffractive structure forming layer, 19 ... cholesteric liquid crystal layer, 20 ... adhesive label, 21 ... adhesive layer, 30 ... recording medium, 31 ... paper, 40 DESCRIPTION OF SYMBOLS ... Adhesive label, 41 ... Adhesive layer, 50 ... Transfer foil, 51 ... Adhesive layer, 52 ... Base material, 100 ... Labeled article, 101 ... Article, 200 ... Verification tool, 300 ... Light source, 400 ... Observer, A1 ... region, A1B1 ... area, A1B2 ... area, A2 ... area, A2B1 ... area, A2B2 ... area, A _F ... fast axis, A _F '... fast axis, A _S ... slow axis, A _S' ... lagging axis, A T _'... transmission axis, L _L1 ... linearly polarized light, L _L2 ... linearly polarized light, L _LC ... left-handed circularly polarized light, L _LE1 Left elliptically polarized light, L _LE2 ... left elliptically polarized light, L _N ... natural light, L _RC ... right circularly polarized light, L _RE1 ... right elliptically polarized light, L _RE2 ... right elliptically polarized light.

Claims (14)

A reflective layer, a first birefringent portion facing a part of the front surface of the reflective layer, and a second birefringent portion facing the other portion of the front surface and having a slow axis direction different from that of the first birefringent portion. A birefringent layer including a refractive part, and a cholesteric liquid crystal layer interposed between the reflective layer and the birefringent layer, each of the first and second birefringent parts having a wavelength λ is Ri retardations near the range of 3 [lambda] / 32 to 5 [lambda] / 32 when the 550 nm,
When the front surface of the reflective layer is viewed from the normal direction, only a part of the first birefringent part overlaps the cholesteric liquid crystal layer, and only a part of the second birefringent part is present. identifying laminate characterized that you have overlapped with the cholesteric liquid crystal layer.   A reflective layer, a first birefringent portion facing a part of the front surface of the reflective layer, and a second birefringent portion facing the other portion of the front surface and having a slow axis direction different from that of the first birefringent portion. A birefringent layer including a refractive part, and a cholesteric liquid crystal layer interposed between the reflective layer and the birefringent layer, each of the first and second birefringent parts having a wavelength The retardation when λ is 550 nm is in the range of 3λ / 32 to 5λ / 32.
  An identification laminate, further comprising a light absorption layer interposed between the reflective layer and the cholesteric liquid crystal layer.   3. The identification laminate according to claim 1, wherein each of the first and second birefringent portions has a retardation of λ / 8 when the wavelength λ is 550 nm.   4. The discriminating laminate according to claim 1, wherein the slow axis of the first birefringent portion is perpendicular to the slow axis of the second birefringent portion. 5.   The discriminating laminate according to any one of claims 1 to 4, wherein the reflective layer includes a diffractive structure. 2. The identification laminate according to claim 1, further comprising a light absorption layer interposed between the reflective layer and the cholesteric liquid crystal layer.   An adhesive label comprising the identification laminate according to any one of claims 1 to 6 and an adhesive layer supported on a back surface of the identification laminate.   7. The identification according to claim 1, wherein the paper is embedded in the paper such that the paper, an adhesive layer supported on one main surface of the paper, and a back surface faces the adhesive layer. A pressure-sensitive adhesive label comprising a laminate.   The base material, the identification laminated body of any one of Claim 1 thru | or 6 with which the front surface was supported by the said base material so that peeling was possible, The adhesion layer supported by the back surface of the said identification laminated body A transfer foil characterized by comprising.   A recording medium comprising: a paper; and the identification laminate according to claim 1 embedded in the paper.   A label comprising: an article whose authenticity is to be confirmed; and an identification laminate according to any one of claims 1 to 6 supported by the article whose authenticity is to be confirmed. Articles with. The identification laminate according to claim 1;
A verification tool comprising a linear polarizer and a second birefringent layer facing the light incident surface of the linear polarizer,
The sum of the retardation at the wavelength λ of the first birefringent portion and the retardation at the wavelength λ of the second birefringent layer is λ / 4, and the wavelength of the second birefringent portion is The sum of the retardation at λ and the retardation of the second birefringent layer at the wavelength λ is λ / 4. To claim 1 2 each of the second birefringent layer and the first birefringent portion and the second birefringent portion, wherein the retardation in the wavelength lambda is lambda / 8 The described kit. A method for discriminating an article whose authenticity is unknown between a genuine product and a non-genuine product,
The authentic product is a labeled product comprising an article whose authenticity is to be confirmed and an identification laminate according to claim 1 supported by the article whose authenticity is to be confirmed.
Discriminating between the genuine product and the non-genuine product based on an image that is visible by observing the product with an unknown authenticity through a verification tool. ,
The verification tool includes a linear polarizer and a second birefringent layer facing the light incident surface of the linear polarizer, and the retarder at the wavelength λ of each of the first and second birefringent portions. Deployment and, wherein the said sum of the azure terpolymers CONDition put on the wavelength lambda of the second birefringent layer is lambda / 4.

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