JP2008139508A - Layered body, adhesive label, recording medium, article with label, verifying tool, kit and discrimination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to thin a birefringent layer without damaging visibility of a visualized latent image. <P>SOLUTION: The layered body 10 for discrimination is provided with: a reflection layer 13; and the refringent layer 12 including a first birefringent part 12a which faces a part of the front surface of the reflection layer 13 and second birefringent parts 12b which face other parts of the front surface and have slow axis directions different from the slow axis direction of the first birefringent part 12a, wherein each of first and second birefringent parts 12a, 12b has a retardation at wavelength λ=550 nm which falls into the range of 3λ/32 to 5λ/32. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 a true / false decision because it is difficult for a general user to apply to the article. Typical covert techniques utilize 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 different phase axis directions, and each of the first and second birefringent portions has a retardation of 3λ when the wavelength λ is 550 nm. An identification laminate is provided that is in the range of / 32 to 5λ / 32.

  According to the 2nd side surface of this invention, the adhesive label characterized by having comprised the laminated body which concerns on a 1st side surface, and the adhesion layer supported by the back surface of the said laminated body is provided.

  According to the 3rd side surface of this invention, it comprised the laminated body which concerns on a 1st side surface, the base material which supported the front surface of the said laminated body so that peeling was possible, and the adhesion layer supported by the back surface of the said laminated body. A featured transfer foil is provided.

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

  According to a fifth aspect of the present invention, there is provided a label comprising: an article whose authenticity is to be confirmed; and a laminate according to the first side surface supported by the article whose authenticity is to be confirmed. Articles are provided.

  According to a sixth aspect of the present invention, there is provided a linear polarizer and a birefringent layer facing the light incident surface of the linear polarizer, and the birefringent layer has a retardation when the wavelength λ is 550 nm. Is provided in the range of 3λ / 32 to 5λ / 32.

  According to the seventh 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 discriminating laminate including a first birefringent layer including a second birefringent portion having a different phase axis direction, a linear polarizer, and a second facing the light incident surface of the linear polarizer A verification tool including a birefringent layer, 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 and the sum of the retardation at the wavelength λ of the second birefringent portion and the retardation at the wavelength λ of the second birefringent layer is λ / 4. A kit is provided.

  According to an eighth 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. An identification laminate supported by an article whose thickness is to be confirmed, wherein the identification laminate includes a reflective layer and a first composite facing a part of the front surface of the reflective layer. A first birefringent layer including a second birefringent portion facing a refractive portion and another portion of the front surface and having a slow axis direction different from that of the first birefringent portion, The first retardation at the wavelength λ of the first and second portions is less than λ / 4, and the authenticity is determined based on an image that is visible by observing the article with an unknown authenticity through a verification tool. Discriminating between the genuine product and the non-genuine product, and the verification The tool includes a linear polarizer and a second birefringent layer facing a light incident surface of the linear polarizer, and the second retardation at the wavelength λ of the first retardation and the second birefringent layer. A method is provided characterized in that the sum with the retardation 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 a layered product for identification according to one embodiment 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, an alignment film 17, and a birefringent layer 12. The reflective layer 13, the alignment film 17, and the birefringent layer 12 are sequentially stacked on the base material 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 13 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 13, a dielectric multilayer film in which high refractive index layers and low refractive index layers are alternately stacked may be used.

  When the substrate 16 is used, the reflective layer 13 can be formed on the substrate 16. The reflective layer 13 can be formed by, for example, vapor deposition, sputtering, or ion plating. The thickness of the reflective layer 13 is, for example, in the range of about 10 nm to about 100 nm. The reflective layer 13 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 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 substrate 16 is omitted, the reflective layer 13 may be formed on the birefringent layer 12 as described later for the transfer foil. In this case, the reflective layer 13 can be formed by the same method as described above. Or when the base material 16 is abbreviate | omitted, you may use as the reflection layer 13 what can handle itself independently like a metal foil and a ceramic board.

  In the case where the reflective layer 13 is light transmissive 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 13. 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 13 or may face only a part of the back surface of the reflection layer 13. The light absorption layer can be formed by, for example, printing or coating.

  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 reflective layer 13 is formed on the birefringent layer 12, the alignment film 17 may face the reflective layer 13 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 12 a faces a part of the front surface of the reflective layer 13. The second birefringent portion 12 b faces the other part of the front surface of the reflective layer 13.

  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 reflective layer 13. Alternatively, an optically isotropic transparent layer may be interposed between the birefringent layer 12 and the reflective layer 13.

  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 this liquid crystal material, for example, a liquid crystal material that is solid in the use temperature range of the laminate 10 and exhibits a nematic phase or a smectic phase, typically 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 polymer liquid crystal layer is formed on the alignment film 17. The polymer liquid crystal layer can be formed using, for example, a gravure coating method or a micro gravure coating method. Next, the polymer liquid crystal layer is heated to a temperature equal to or lower than a 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 direction above the first alignment portion 17a and the second alignment portion 17b, the polymer 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 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 13. The main surface of the diffractive structure forming layer 18 on the reflective layer 13 side includes a convex pattern or a concave pattern. The front surface of the reflective layer 13 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 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 is formed on the flat diffractive structure forming layer 18. Next, the press plate is pressed against the reflective layer 13 while being heated. Thereby, the convex pattern or the concave pattern is transferred to the reflective layer 13 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.

  The front surface of the laminate 10 described with reference to FIGS. 1 to 4 includes a region AA1 corresponding to the first birefringent portion 12a and a region AA2 corresponding to the second birefringent portion 12b. Each of the areas AA1 and AA2 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 area AA1 and the area AA2. 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 occurs between the area AA1 and the area AA2. Thereby, the latent image is visualized. Since the laminate 10 described with reference to FIGS. 3 and 4 has the above-described diffraction structure, forgery or the like may occur compared to the laminate 10 described with reference to FIGS. 1 and 2. More difficult.

Next, the visualization of the latent image will be described.
5 and 6 are diagrams schematically illustrating an example of a method for visualizing the latent image held by the stacked body illustrated in FIGS. 1 and 2. FIG. 5 illustrates a state in which the area AA1 reflects light. FIG. 6 illustrates a state where the area AA2 reflects light.

5 and 6 includes a λ / 8 wavelength plate as the first birefringent portion 12a and the second birefringent portion 12b. That is, when each of the first birefringent portion 12a and the second birefringent unit 12b to and wavelength are oblique to the plane of polarization slow axis A _S is made incident linearly polarized light of lambda, polarization A first linearly polarized light whose plane is parallel to the fast axis A _F and a second linearly polarized light whose plane of polarization is parallel to the slow axis A _S and whose phase is delayed by λ / 8 with respect to the first linearly polarized light. Exit. Then, in the laminate 10, and the slow axis A _S and the slow axis A _S and the angle formed by the second birefringent portion 12b of the first birefringent portion 12a and 90 °.

  In the method shown in FIGS. 5 and 6, the light from the light source 300 is transmitted through the verification tool 200 and the transmitted light is irradiated on 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 arranged so that the slow axis A _S ′ of the birefringent layer 202 is inclined with respect to the plane of polarization of the linearly polarized light transmitted by the linear polarizer 201. 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 method of FIGS. 5 and 6, as an example, the following configuration is adopted for the verification tool 200. 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 °.

5 and 6, the laminate 10 and the verification tool 200 are arranged so that the linear polarizer 201 faces the light source 300 and the observer 400 and the birefringent layer 202 faces the laminate 10. Yes. Here, as an example, a 'and parallel 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 orthogonal. 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 stacked body 10 is observed without using the verification tool 200, both the areas AA1 and AA2 appear as bright portions, and no difference in brightness occurs between them. Therefore, in this case, it is difficult to find the difference between the area AA1 and the area AA2, and the latent image formed by the area AA1 or the area AA2 is not visualized.

When the front surface of the stacked body 10 is observed using the verification tool 200, as shown in FIGS. 5 and 6, light emitted from the light source 300, for example, natural light L _N , is applied to the linear polarizer 201 of the verification tool 200. Make it incident. Here, for simplification, it is assumed that the light source 300 emits only light having a wavelength of λ. The linear polarizer 201 transmits the linearly polarized light L _PS (hereinafter referred to as S-polarized light) whose natural light L _N has a polarization plane parallel to the transmission axis A _T ′, and the polarization plane corresponds to the transmission axis A _T ′. And linearly polarized light L _PP (hereinafter referred to as P-polarized light) is absorbed.

The S-polarized light L _PS emitted from the linear polarizer 201 enters the birefringent layer 202. The birefringent layer 202 converts the S-polarized light L _PS into the left elliptical polarized light L _LE . When the left elliptically polarized light L _LE is viewed from the reflective layer 13 side, the long axis of the ellipse formed by the locus of the end of the electric field vector is clockwise with respect to the slow axis A _S ′ of the birefringent layer 202. Tilted 45 °.

The left elliptically polarized light L _LE emitted from the birefringent layer 202 is incident on the first birefringent portion 12a as shown in FIG. 5 in the portion corresponding to the region AA1. The first birefringent portion 12a converts the left elliptically polarized light L _LE into left circularly polarized light L _LC .

Left circularly polarized light L _LC emitted from the first birefringent portion 12a is reflected by the reflective layer 13. Thereby, the left circularly polarized light L _LC is converted into the right circular polarized light L _RC .

The right circularly polarized light L _RC from the reflective layer 13 is incident on the first birefringent portion 12a. The first birefringent portion 12a converts the right circularly polarized light _LRC into the right elliptically polarized light _LRE . Incidentally, when viewed this right elliptically polarized light L _RE from the viewer 400 side, the major axis of the ellipse trajectory of the end of the electric field vector is formed, the right against the slow axis A _S of the first birefringent portion 12a Tilt around 45 °.

The right elliptically polarized light L _RE emitted from the first birefringent portion 12 a enters the birefringent layer 202. The birefringent layer 202 converts the right elliptically polarized light L _RE into P polarized light L _PP .

The P-polarized light L _PP emitted from the birefringent layer 202 enters the linear polarizer 201. The linear polarizer 201 absorbs the P-polarized light L _PP . Therefore, the area AA1 does not emit light toward the observer 400.

In the portion corresponding to the region AA2, the left elliptically polarized light L _LE emitted from the birefringent layer 202 is incident on the second birefringent portion 12b as shown in FIG. The second birefringent portion 12b converts the left elliptical polarized light L _LE into S polarized light L _PS .

The S-polarized light L _PS emitted from the second birefringent portion 12b is reflected by the reflective layer 13 and enters the second birefringent portion 12b. The second birefringent portion 12b converts the S-polarized light _LPS into the left elliptical polarized light _LLE .

The left elliptically polarized light L _LE emitted from the second birefringent portion 12 b enters the birefringent layer 202. The birefringent layer 202 converts the left elliptically polarized light L _LE into S polarized light L _PS .

The S-polarized light L _PS emitted from the birefringent layer 202 enters the linear polarizer 201. The linear polarizer 201 transmits the S-polarized light _LPS . Therefore, the area AA2 emits light toward the viewer 400.

  Thus, the area AA1 does not emit light toward the viewer 400, and the area AA2 emits light toward the viewer 400. Therefore, the viewer 400 perceives the areas AA1 and AA2 as dark parts and bright parts, respectively. As described above, the latent image can be visualized.

  When the verification tool 200 is rotated around the light beam, the positions of the bright part and the dark part are switched. For example, when the verification tool 200 is rotated by 90 ° around the light beam, the positions of the bright part and the dark part are opposite to those described with reference to FIGS.

  FIG. 7 is a plan view illustrating an example of an image that can be observed when the latent image held by the stacked body illustrated in FIGS. 3 and 4 is visualized. FIG. 8 is a plan view illustrating another example of an image that can be observed when the latent image held by the stacked body illustrated in FIGS. 3 and 4 is visualized.

  FIG. 7 shows an image that can be observed when the latent image held by the laminate 10 shown in FIGS. 3 and 4 is visualized by the method described with reference to FIGS. 5 and 6. In this case, the areas AA1 and AA2 are seen as a dark part and a bright part, respectively. Therefore, in the diffraction image HG, the part corresponding to the area AA1 cannot be visually recognized, and only the part corresponding to the area AA2 can be visually recognized.

  FIG. 8 shows an image that can be observed when the verification tool 200 is rotated by 90 ° around the normal to the paper surface from the state shown in FIG. In this case, the areas AA1 and AA2 are seen as a bright part and a dark part, respectively. Therefore, in the diffraction image HG, the part corresponding to the area AA2 cannot be visually recognized, and only the part corresponding to the area AA1 can be visually recognized.

  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 layered body 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 13. 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 13. 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, the 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.

The laminate 10 can be used in various forms as described below.
FIG. 9 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. 10 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.

  FIG. 11 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. 12 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 laminate 10 includes an alignment film 17, a birefringent layer 12, and a reflective layer 13 on a substrate 52. The alignment film 17, the birefringent layer 12, and the reflective layer 13 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.

  In addition, when the laminated body of the birefringent layer 12 and the reflective layer is peeled from the substrate 10, the alignment film 17 remains on the substrate 52 or causes cohesive failure of 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 13 may include the diffractive structure described with reference to FIGS. 3 and 4.

  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 polymer liquid crystal material are tougher than the same thickness layers made of other polymer materials. Therefore, particularly when the birefringent layer 12 is made of 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. 13: is sectional drawing which shows roughly an example of the labeled article containing the laminated body for forgery prevention. 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. 9 or the adhesive label 40 shown in FIG. 11 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 coating liquid containing acrylic polyol and isocyanate was coated on the birefringent 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 figure which shows schematically an example of the method of visualizing the latent image which the laminated body shown in FIG.1 and FIG.2 hold | maintains. The figure which shows schematically an example of the method of visualizing the latent image which the laminated body shown in FIG.1 and FIG.2 hold | maintains. The top view which shows an example of the image which can be observed when the latent image currently hold | maintained at the laminated body shown in FIG.3 and FIG.4 is visualized. The top view which shows the other example of the image which can be observed when the latent image which the laminated body shown in FIG.3 and FIG.4 hold | maintains is visualized. 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 roughly 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 ... Discrimination laminated body, 12 ... Birefringent layer, 12a ... 1st birefringent part, 12b ... 2nd birefringent part, 13 ... Reflective layer, 16 ... Base material, 17 ... Orientation film, 17a ... 1st 1 orientation part, 17b ... 2nd orientation part, 18 ... diffraction structure formation layer, 20 ... adhesive label, 21 ... adhesive layer, 30 ... recording medium, 31 ... paper, 40 ... adhesive label, 41 ... adhesive layer, 50 ... transfer Foil, 51 ... adhesive layer, 52 ... substrate, 100 ... labeled article, 101 ... article, 200 ... verification tool, 201 ... linear polarizer, 202 ... birefringent layer, 300 ... light source, 400 ... observer, AA1 ... Area, AA2 ... Area, A _F ... Fast axis, A _F '... Fast axis, A _S ... Slow axis, A _S ' ... Slow axis, A _T '... Transmission axis, HG ... Diffraction image, L _LC ... left circularly polarized light, L _LE ... left elliptically polarized light, L _N ... natural light, L _PP ... linearly polarized light, L _PS ... linearly polarized light, L _RC ... right circularly polarized light, L _RE ... right Circularly 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 each of the first and second birefringent parts has a retardation in the range of 3λ / 32 to 5λ / 32 when the wavelength λ is 550 nm. The laminate for identification characterized by being in.   2. The 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.   The laminate according to claim 1 or 2, wherein the slow axis of the first birefringent part is perpendicular to the slow axis of the second birefringent part.   The laminated body according to claim 1, wherein the reflective layer includes a diffractive structure.   An adhesive label comprising the laminate according to any one of claims 1 to 4 and an adhesive layer supported on a back surface of the laminate.   The laminate according to any one of claims 1 to 4, comprising a base material that releasably supports a front surface of the laminate, and an adhesive layer supported on a back surface of the laminate. Transfer foil.   A recording medium comprising paper and the laminate according to any one of claims 1 to 4 embedded in the paper.   An labeled article comprising: an article whose authenticity is to be confirmed; and a laminate according to any one of claims 1 to 4 supported by the article whose authenticity is to be confirmed. .   A linear polarizer, and a birefringent layer facing the light incident surface of the linear polarizer, wherein the birefringent layer has a retardation of 3λ / 32 to 5λ / 32 when the wavelength λ is 550 nm. A verification tool characterized by being within range.   The verification tool according to claim 9, wherein the birefringent layer has a retardation of λ / 8 when the wavelength λ is 550 nm. 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 discriminating laminate comprising a first birefringent layer including a refractive part;
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.   The retardation at the wavelength λ of each of the first birefringent portion, the second birefringent portion, and the second birefringent layer is λ / 8. Kit.   The kit according to claim 11 or 12, wherein the wavelength λ is 550 nm. 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 supported by the article whose authenticity is to be confirmed,
The discriminating laminate includes a reflective layer, a first birefringent portion facing a part of the front surface of the reflective layer, and another portion of the front surface, and the first birefringent portion is a slow axis. A first birefringent layer including a second birefringent portion having different directions, and the first retardation at the wavelength λ of the first and second portions is less than λ / 4,
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 a light incident surface of the linear polarizer, and the first retardation and the second birefringent layer at the wavelength λ. A method characterized in that the sum with the second retardation is λ / 4.

Images