JP5211473B2 - Laminated body, adhesive label, recording medium, and labeled article - 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 a forgery prevention technique using both an overt technique and a covert technique. In this anti-counterfeiting technology, for example, a label including a multilayer film formed by alternately laminating a birefringent first light-transmitting layer and second light-transmitting layers having optical characteristics different from the first light-transmitting layer is used. In this multilayer film, the first light transmissive layer and the second light transmissive layer have the same refractive index in the first direction in the first plane perpendicular to the main surface of the first light transmissive layer. The refractive indexes in the second direction in the second plane perpendicular to the main surface and the first plane are different. Therefore, the interface between the first light transmissive layer and the second light transmissive layer does not reflect linearly polarized light whose polarization plane (vibration plane of the electric field vector) is parallel to the first plane, and the polarization plane is the second plane. Reflects some of the parallel linearly polarized light. Therefore, when the multilayer film is observed through a linear polarizer, the brightness of the multilayer film changes according to the direction of the transmission axis of the linear polarizer. In addition, when the multilayer film is observed without passing through a polarizer, a blue shift is caused by increasing the angle formed by the observation direction and the normal line of the multilayer film. That is, the interference color is shifted to the short wavelength side. Using these optical characteristics, genuine products and non-genuine products are discriminated.

The label used in this anti-fake technology can achieve low cost and high durability. However, the optical characteristics described above can be reproduced without using the multilayer film. For example, the above optical characteristics can be reproduced with a laminate of a general color shift film and an absorbing polarizing layer. Therefore, this label is relatively easy to counterfeit.
JP 2004-354430 A

  An object of the present invention is to make it difficult to forge a label used for discrimination between genuine products and non-genuine products.

According to a first aspect of the present invention, the first and second portions aligned in-plane direction of a reflection-type polarizing layer I containing, each of said first and second portions, the first birefringent 1 A reflective polarizing layer formed by alternately laminating a light transmissive layer and a second light transmissive layer having different optical characteristics from the first light transmissive layer; and the polarization layer positioned on the front side of the polarizing layer and the polarized light A birefringent layer facing only at the position of the first portion, and an optically isotropic transparent layer covering the front surface of the polarizing layer and the birefringent layer, the polarizing layer A discriminating laminate is provided that includes a convex pattern or a concave pattern as a diffractive structure that diffracts the light transmitted or reflected by the light.

  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 a third aspect of the present invention, there is provided a paper, a pressure-sensitive adhesive layer supported on one main surface of the paper, and a lamination according to the first side surface embedded in the paper so that a back surface faces the pressure-sensitive adhesive layer. An adhesive label characterized by comprising a body 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 the present invention, it is possible to make it difficult to forge a label used for discrimination between a genuine product and a non-genuine product.

  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. 3 and 4 are perspective views schematically showing a reflective polarizing layer included in the laminate shown in FIGS. 1 and 2. FIG. 5 is a cross-sectional view schematically showing a part of the reflective polarizing layer shown in FIGS. FIG. 6 is an exploded perspective view schematically showing a part of the reflective polarizing layer shown in FIGS. 3 and 4.

  As shown in FIG. 2, the identification laminate 10 includes a reflective polarizing layer 11, a birefringent layer 12, a light absorbing layer 13 a, and an overcoat layer 14.

  Here, the term “polarizing layer” means a layer functioning as a linear polarizer unless otherwise specified. The term “polarizer” includes “linear polarizer”, “elliptical polarizer”, and “circular polarizer”, and does not include the concept of shape.

The reflective polarizing layer 11 is a layer whose reflectance changes when the polarization plane of linearly polarized light as incident light is rotated. As shown in FIG. 3, the reflective polarizing layer 11 is ideally linearly polarized L when the transmission axis _AT of the reflective polarizing layer 11 and the polarization plane of the linearly polarized light L _LP as incident light are parallel to each other. Transmits _LP without reflecting. When the angle formed by the polarization plane of the linearly polarized light L _LP with respect to the transmission axis _AT is increased, the light component reflected by the reflective polarizing layer 11 increases. As shown in FIG. 4, when the polarization plane of the linearly polarized light L _LP and the transmission axis _AT are orthogonal, the reflective polarizing layer 11 reflects the most light component.

  As shown in FIG. 5, the reflective polarizing layer 11 has a structure in which first light transmissive layers 11a and second light transmissive layers 11b are alternately stacked. When the number of the first light transmissive layers 11a and the number of the second light transmissive layers 11b included in the reflective polarizing layer 11 are increased, the above-described change in reflectance is increased. However, if these numbers are increased, the reflective polarizing layer 11 becomes thicker. The sum of the number of the first light transmissive layers 11a and the number of the second light transmissive layers 11b is, for example, in the range of 2 to 1000, and typically in the range of 100 to 500.

  The first light transmissive layer 11a has birefringence. The first light transmissive layers 11a are arranged so that their slow axes are substantially parallel.

  The second light transmissive layer 11b is different in optical characteristics from the first light transmissive layer 11a. The second light transmissive layer 11b may be optically isotropic, or may have birefringence. The second light transmissive layers 11b are arranged so that their slow axes are substantially parallel when they have birefringence.

For the first linearly polarized light incident on the reflective polarizing layer 11 from the normal direction, substantially equal to the refractive index n _b1 of the refractive index n _a1 indicated by the first light transmitting layer 11a indicated by the second light transmissive layer 11b . Therefore, each interface between the first light transmissive layer 11a and the second light transmissive layer 11b transmits the first linearly polarized light. In addition, for the second linearly polarized light that is incident on the reflective polarizing layer 11 from the normal direction and has a polarization plane perpendicular to the polarization plane of the first linearly polarized light, the refractive index _na2 indicated by the first light transmitting layer 11a. Is different from the refractive index n _{b2 of} the second light transmissive layer 11b. Therefore, each interface between the first light transmissive layer 11a and the second light transmissive layer 11b reflects a part of the second linearly polarized light. For this reason, the reflection-type polarizing layer 11, is transmitted through the first linear polarized light having a polarization plane parallel to the transmission axis A _T shown in FIG. 6, the plane of polarization parallel to the reflection axis A _R shown in FIG. 6 The second linearly polarized light is reflected.

The absolute value of the difference between the refractive index n _a1 and the refractive index n _b1 is smaller than the absolute value of the difference between the refractive index n _a2 and the refractive index n _b2, and is typically almost zero. When this absolute value is reduced, the reflectance of the first linearly polarized light at each interface between the first light transmissive layer 11a and the second light transmissive layer 11b is reduced.

The absolute value of the difference between the refractive index n _a2 and the refractive index n _b2 is, for example, 0.03 or more, and typically 0.05 or more. When this absolute value is increased, the reflectance of the second linearly polarized light at each interface between the first light transmitting layer 11a and the second light transmitting layer 11b increases.

As the first light transmissive layer 11a, for example, a stretched film imparted with birefringence by uniaxial stretching or biaxial stretching can be used. As a material for the stretched film, for example, polystyrene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, or the like can be used. A birefringent inorganic layer may be used as the first light transmissive layer 11a. However, when a stretched film is used, the refractive indexes _na1 and _na2 can be easily adjusted. For example, a polyvinyl chloride film has a higher refractive index when stretched. The polymethyl methacrylate film has a low refractive index when stretched. And the refractive index of a stretched film changes according to a stretch ratio and / or stretch temperature.

  For example, a stretched film can be used as the second light transmissive layer 11b. As the material of the stretched film, for example, the same material as exemplified with respect to the first light transmissive layer 11a can be used. A birefringent or optically isotropic inorganic layer may be used as the second light transmissive layer 11b. However, when a stretched film is used as the first light transmissive layer 11a, the reflective polarizing layer 11 can be easily manufactured by using a stretched film as the second light transmissive layer 11b. That is, a laminated film obtained by alternately laminating first and second films having different materials is prepared, and the laminated film is uniaxially or biaxially stretched. By using appropriate materials for the first and second films and appropriately setting the stretching ratio and the stretching temperature, the reflective polarizing layer 11 having the above-described optical characteristics can be obtained.

  The optical thicknesses of the first light transmissive layer 11a and the second light transmissive layer 11b are, for example, in the range of 0.09 μm to 0.70 μm. For example, when the optical thickness is set to 0.38 μm, it looks blue-purple, and when the optical thickness is set to 0.68 μm, it looks red. In addition, when such a reflective polarizing layer 11 is observed without using a polarizer, a blue shift is caused by increasing the angle formed by the observation direction and the normal line of the reflective polarizing layer 11. That is, the interference color is shifted to the short wavelength side.

The birefringent layer 12 faces a part of the front surface of the reflective polarizing layer 11. The birefringent layer 12 has substantially uniform optical characteristics in the plane. The optical axis of the birefringent layer 12 is oblique to the transmission axis A _T and the reflection axis A _R of substantially parallel and reflective polarizing layer 11 to the major surface of the reflective polarizing layer 11. For example, the birefringent layer 12 and the reflective polarizing layer 11, the optical axis of the birefringent layer 12 forms an angle of approximately 45 ° to the transmission axis A _T and the reflection axis A _R of the reflective polarizing layer 11 Arrange as follows.

  The area AA1 corresponding to the birefringent layer 12 in the front surface of the laminate 10 forms a latent image that is difficult to distinguish from the adjacent area AA2. 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 the polarizer, a difference in brightness occurs between the area AA1 and the area AA2. Thereby, the latent image is visualized.

  The birefringent layer 12 may be in direct contact with the front surface of the reflective polarizing layer 11. Alternatively, a transparent layer may be interposed between the birefringent layer 12 and the reflective polarizing layer 11.

  As the birefringent layer 12, for example, a birefringent stretched film can be used. As this stretched film, for example, a uniaxially or biaxially stretched polyolefin film and polyester film can be used. When a part of the birefringent stretched film is optically isotropic, that part is excluded from the birefringent layer 12.

  A liquid crystal material may be used as the material of the birefringent layer 12. 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, for example, by forming a thin film pattern made of a liquid crystal material and applying heat and pressure to the thin film pattern, the alignment of the liquid crystal can be made uniform. Alternatively, a birefringent layer 12 in which the orientation of the mesogenic groups of the liquid crystal molecules is aligned can be obtained by forming a thin film pattern made of a low molecular weight liquid crystal material on the alignment film and causing polymerization of the liquid crystal material. . The alignment film is obtained, for example, by forming a resin layer such as polyimide and performing an alignment treatment such as rubbing on the resin layer.

  The light absorption layer 13 a faces the back surface of the reflective polarizing layer 11. The light absorption layer 13a may face the entire back surface of the reflective polarizing layer 11, or may face only a part thereof. Further, the light absorption layer 13a may be omitted.

  The light absorption layer 13 a may be in direct contact with the back surface of the reflective polarizing layer 11. Alternatively, an optically isotropic transparent layer may be interposed between the light absorption layer 13a and the reflective polarizing layer 11.

  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 back surface of the reflective polarizing layer 11. Or the light absorption layer 13a is obtained by apply | coating the previous ink on a base material. In this case, the light absorption layer 13a can be attached to the back surface of the reflective polarizing layer 11 together with the base material.

  The light absorption layer 13a may be black or other colors. The light absorption layer 13a may include a plurality of portions having different colors and arranged in the in-plane direction.

  When the light absorption layer 13a is black and the latent image is not visualized, the colors of the areas AA1 and AA2 are white due to the light reflection of the reflective polarizing layer 11. When the latent image is visualized, one of the areas AA1 and AA2 changes to black. If the light absorption layer 13a is black, the contrast ratio of these regions is maximized when the latent image is visualized.

  When the light absorbing layer 13a that absorbs only a part of visible light and reflects the other part is used, the colors of the areas AA1 and AA2 are reflected by the reflective polarizing layer 11 when the latent image is not visualized. This is a color generated by additive color mixing of the white color caused by the color and the color caused by the reflection by the light absorption layer 13a. When the latent image is visualized, the intensity of the colored light due to the reflection by the light absorption layer 13a is weak in one of the areas AA1 and AA2, and the intensity of the white light due to the reflection by the reflective polarizing layer 11 is weak on the other. Become.

  The overcoat layer 14 covers the front surface of the reflective polarizing layer 11 and the birefringent layer 12. The overcoat layer 14 is an optically isotropic transparent layer, typically a transparent resin layer. The overcoat layer 14 flattens the uneven surface formed by the reflective polarizing layer 11 and the birefringent layer 12. This obfuscates the presence of the birefringent layer 12. The overcoat layer 14 may be omitted.

  The overcoat layer 14 is obtained, for example, by applying a transparent printing ink to the reflective polarizing layer 11 and the birefringent layer 12. For the application of the printing ink, for example, a coating method such as gravure and microgravure can be used.

Next, the visualization of the latent image will be described.
7 and 8 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. 7 illustrates a state in which the area AA1 reflects light. FIG. 8 illustrates a state in which the area AA2 reflects light.

The laminated body 10 shown in FIGS. 7 and 8 includes a half-wave plate as the birefringent layer 12. The angle formed by the reflection axis A _R of the reflective polarizing layer 11 and the slow axis A _S of the birefringent layer 12 is 45 °.

  In the method illustrated in FIGS. 7 and 8, the front surface of the stacked body 10 is observed through the verification tool 200 while irradiating the front surface of the stacked body 10 with natural light. Here, as an example, an absorptive polarizing layer such as a polarizing layer in which a stretched polyvinyl alcohol layer is impregnated with iodine is used as the verification tool 200. Further, 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.

As shown in FIG. 7, the natural light L _N from the light source 300 is incident on the birefringent layer 12 in the portion corresponding to the region AA1. The birefringent layer 12 transmits this natural light _LN .

Natural light L _N emitted from the birefringent layer 12 enters the reflective polarizing layer 11. Reflective polarizing layer 11, of the natural light L _N, the plane of polarization is transmitted through the first linearly polarized light L _L1 parallel to the transmission axis A _T, the second linearly polarized light the polarization plane is parallel to the reflection axis A _R L _L2 To reflect.

The first linearly polarized light L _L1 emitted from the reflective polarizing layer 11 is absorbed by the light absorbing layer 13a. On the other hand, the second linearly polarized light L _L2 emitted from the reflective polarizing layer 11 enters the birefringent layer 12. The birefringent layer 12 converts the second linearly polarized light L _L2 into the first linearly polarized light L _L1 .

The first linearly polarized light L _L1 emitted from the birefringent layer 12 enters the verification tool 200. If the transmission axis A _T validation tool 200 as shown in FIG. 7 'is perpendicular to the reflection axis A _R of the reflective polarizing layer 11, the verification device 200 is ideally first linearly polarized light L _L1 Permeate without absorbing. Therefore, the light component reflected by the reflective polarizing layer 11 reaches the observer 400.

In the portion corresponding to the area AA2, the natural light L _N from the light source 300 is incident on the reflective polarizing layer 11, as shown in FIG. Of the natural light L _N , the reflective polarizing layer 11 transmits the first linearly polarized light L _L1 and reflects the second linearly polarized light L _L2 .

The first linearly polarized light L _L1 emitted from the reflective polarizing layer 11 is absorbed by the light absorbing layer 13a. On the other hand, the second linearly polarized light L _L2 emitted from the reflective polarizing layer 11 enters the verification tool 200. If the transmission axis A _T validation tool 200, as shown in FIG. 8 'is perpendicular to the reflection axis A _R of the reflective polarizing layer 11, the verification device 200 absorbs second linearly polarized light L _L2. Therefore, the light component reflected by the reflective polarizing layer 11 does not reach the observer 400.

  In this way, the verification tool 200 transmits the reflected light from the area AA1 and absorbs the reflected light from the area AA2. Therefore, the viewer 400 perceives the areas AA1 and AA2 as a bright part and a dark part, respectively. As described above, the latent image can be visualized.

Incidentally, the transmission axis A _T validation tool 200 'varies the angle formed with respect to the reflection axis A _R of the reflective polarizing layer 11, the bright portion and the dark portion of the position are interchanged. For example, when the transmission axis A _T ′ is parallel to the reflection axis A _R , the positions of the bright part and the dark part are opposite to those described with reference to FIGS.

  As described above, in the laminate 10, the reflective polarizing layer 11 and the birefringent layer 12 are combined. The birefringent layer 12 faces only a part of the reflective polarizing layer 11, thereby forming a latent image. Therefore, the laminate 10 is difficult to counterfeit.

  Further, as described above, the light applied to the stacked body 10 for visualizing the latent image need not be linearly polarized light. Therefore, it is not necessary to position the verification tool 200 in the vicinity of the stacked body 10. Therefore, this technique makes it easier to visualize the latent image as compared with the case where the laminated body 10 must be irradiated with linearly polarized light in order to visualize the latent image.

  In the method described with reference to FIGS. 7 and 8, natural light is used as light applied to the stacked body 10 in order to visualize the latent image, but linearly polarized light may be used instead. For example, the verification tool 200 may be positioned in the vicinity of the stacked body 10 and the stacked body 10 may be irradiated with linearly polarized light transmitted by the verification tool 200.

  In the method described with reference to FIGS. 7 and 8, the polarizing layer is used as the verification tool 200, but the verification tool 200 may not be a layer. For example, a polarizing prism may be used.

  Moreover, although the verification tool 200 used by the method demonstrated with reference to FIG.7 and FIG.8 is a linear polarizer, you may use an elliptical polarizer or a circular polarizer instead. For example, when a quarter wave plate is used as the birefringent layer 12 instead of the half wave plate, a circular polarizer can be used.

  FIG. 9 is a diagram schematically illustrating another example of a method for visualizing the latent image held by the stacked body illustrated in FIGS. 1 and 2.

In this method, a transparent body 200 ′ such as a transparent plate is used as a verification tool. Specifically, the natural light L _N emitted from the light source 300 is irradiated onto the laminated body 10, and the light reflected by the laminated body 10 is incident on the transparent body 200 ′. Here, as an example, the reflected light from the area AA1 is linearly polarized light (hereinafter referred to as S wave) L _S whose polarization plane is perpendicular to the main surface of the transparent body 200 ′, and the reflected light from the area AA2 is polarized light. It is assumed that the plane is linearly polarized light (hereinafter referred to as P wave) L _P perpendicular to the plane of polarization of the S wave L _S.

The incident angle θ of the S wave L _S and the P wave L _P with respect to the transparent body 200 ′ is made substantially equal to the Brewster angle. For example, when a glass plate having a refractive index of about 1.5 is used as the transparent body 200 ′, the incident angle is set to about 56 °.

In this way, most of the light reflected by the transparent body 200 ′ becomes the S wave L _S. That is, the reflected light from the area AA1 among the reflected light from the stacked body 10 reaches the observer 400, but the reflected light from the area AA2 hardly reaches. Therefore, the viewer 400 perceives the areas AA1 and AA2 as a bright part and a dark part, respectively. As described above, the latent image can be visualized.

  In the arrangement shown in FIG. 9, when the laminate 10 is rotated by 90 ° around the normal line, the regions AA1 and AA2 appear as dark portions and bright portions, respectively.

  A light absorption layer can be provided on the back side of the transparent body 200 ′. Employing this configuration improves the contrast ratio of the visible image.

  The transparent body 200 'is typically a transparent plate, but may not be a transparent plate as long as it has a smooth surface. The transparent body 200 ′ may be used only for the visualization, or may be used for other purposes such as a display cover plate mounted on a portable device. Good.

  Since the laminate 10 described above includes the reflective polarizing layer 11, when the front surface of the laminate 10 is directly observed without using the verification tool 200, the front surface of the laminate 10 looks bright. Therefore, a highly visible print pattern can be formed on the front surface of the laminate 10.

  FIG. 10 is a plan view schematically showing a modification of the laminate shown in FIGS. 1 and 2. FIG. 11 is a cross-sectional view taken along line XI-XI of the stacked body shown in FIG.

  The laminate 10 shown in FIGS. 10 and 11 is the same as the laminate 10 described with reference to FIGS. 1 and 2 except that the laminate 10 further includes a printed pattern 15 formed on the overcoat layer 14. It has a structure. Thus, the printing pattern 15 can be formed on the overcoat layer 14.

  The print pattern 15 may be interposed between the overcoat layer 14 and the birefringent layer 12. Alternatively, the print pattern 15 may be interposed between the overcoat layer 14 and the reflective polarizing layer 11. Alternatively, the print pattern 15 may be interposed between the birefringent layer 12 and the reflective polarizing layer 11.

The laminated body 10 described above may include a diffractive structure.
FIG. 12 is a plan view schematically showing another modification of the laminate shown in FIGS. 1 and 2. FIG. 13 is a cross-sectional view taken along line XIII-XIII of the laminate shown in FIG. The stacked body 10 has the same structure as the stacked body 10 described with reference to FIGS. 1 and 2 except that the stacked body 10 further includes a diffraction structure forming layer 18 and a reflective layer 13b.

  The diffractive structure forming layer 18 is interposed between the reflective polarizing layer 11 and the light absorbing layer 13a. In this example, the diffractive structure forming layer 18 is formed on the main surface of the reflective polarizing layer 11 facing the light absorption layer 13a. The main surface of the diffraction structure forming layer 18 on the light absorption layer 13 side includes a convex pattern or a concave pattern. The diffractive structure forming layer 18 is made of a transparent resin such as a thermoplastic resin, for example.

  The reflective layer 13b is interposed between the reflective polarizing layer 11 and the light absorbing layer 13a. In this example, the reflective layer 13b is formed on the main surface of the diffractive structure forming layer 18 facing the light absorbing layer 13a. 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. 12 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, 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 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.

  The reflective layer 13b may have a light transmission property or may not have a light transmission property.

  In the case where the reflective layer 13b does not have optical transparency, the light absorption layer 13a may be omitted. In this case, if the reflectance of the light reflecting layer 13b is high, the latent image cannot be visualized or the visualized latent image is difficult to see. For example, if a light-transmitting colored layer is provided in front of the light reflecting layer 13b, it is possible to prevent the latent image from being visualized and to prevent the visualized latent image from being difficult to see.

  In the case where the reflective layer 13b is light transmissive, the visibility of the visualized latent image can be increased by providing the light absorbing layer 13a. When providing the light absorption layer 13a, the light absorption layer 13a may face the whole 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 13a can be formed by, for example, printing or a coating method.

  The reflective layer 13b can be formed by, for example, vapor deposition, sputtering, or ion plating. In this case, 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 13b may face the entire main surface of the reflective polarizing layer 11, or may face only a part thereof.

  The reflective layer 13b may be formed on the diffractive structure forming layer 18 as described above, or may be formed on a base material (not shown). For example, a base material including a convex pattern or a concave pattern on one main surface is prepared. Next, the reflective layer 13b is formed on the main surface by the above method. Then, this base material and the reflective polarizing layer 11 are bonded together through an adhesive layer. When the substrate is not transparent, the substrate and the reflective polarizing layer 11 are bonded so that the reflective layer 13 b faces the reflective polarizing layer 11. When the substrate is transparent, the substrate and the reflective polarizing layer 11 are bonded so that the reflective layer 13b faces the reflective polarizing layer 11, or the base material faces the reflective polarizing layer 11. Paste together. The reflective layer 13b may be supported on the reflective polarizing layer 11 by such a method.

  As the reflective layer 13b, a material that can be handled by itself, such as a metal foil, may be used. In this case, for example, a transparent adhesive layer is interposed between the reflective layer 13 b and the reflective polarizing layer 11 instead of the diffraction structure forming layer 18. In this case, typically, the light absorption layer 13a is omitted.

  The diffractive structure may be installed in front of the reflective polarizing layer 11. For example, the diffraction structure forming layer 18 may be formed on the front surface of the reflective polarizing layer 11, and the reflective layer 13b having light transmittance may be formed thereon.

  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 reflective polarizing layer 11, the diffractive structure forming layer 18 is not necessary.

  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 laminate 10 has a latent image that is visualized by observation through a polarizer. That is, at least a partial region of the article supporting the laminated body 10 has a latent image that is visualized by observing through the polarizer. Therefore, if an article with unknown authenticity does not have such a latent image, it can be determined that the article is non-authentic.

  In addition, when the laminate 10 is observed without using a polarizer, a blue shift is generated by increasing an angle formed by the observation direction and the normal line of the main surface of the reflective polarizing layer 11. Therefore, when an article whose authenticity is unknown does not include a region that causes such a blue shift, it can be determined that the article is non-authentic.

  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.

  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. 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. 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 labeled article including the laminate shown in FIGS. 1 and 2. This labeled article 100 includes an article 101 and a laminate 10.

  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.

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.

Examples of the present invention will be described below.
DBEF manufactured by 3M (Minnesota Mining & Manufacturing) was prepared as a reflective polarizing layer.

  Next, a polyimide film having a thickness of 0.1 μm was formed on the front surface of the reflective polarizing layer by a gravure coating method. This polyimide film was rubbed in a direction forming an angle of 45 ° with respect to the reflection axis of the reflective polarizing layer to obtain an alignment film.

Next, UV curable liquid crystal UCL-008 (manufactured by Dainippon Ink Co., Ltd.) was pattern printed on the alignment film by a gravure 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 having a difference between the ordinary light refractive index and the extraordinary light refractive index of 0.18 and a thickness of 1.5 μm was obtained. That is, this birefringent layer is a half-wave plate that transmits a pair of linearly polarized light having a wavelength λ of 540 nm and gives a phase difference of λ / 2 to the linearly polarized light.

  Thereafter, an acrylic UV ink was coated on the alignment film and the birefringent layer by a microgravure coating method to form an overcoat layer having a thickness of 5 μm.

  Next, an adhesive layer having a thickness of 30 μm containing a black dye and an acrylic adhesive was formed on the back surface of the reflective polarizing layer. Furthermore, a color shift ink containing a pearl pigment was printed on the overcoat layer. An adhesive label was obtained as described above.

  Next, this adhesive label was affixed on the base material. And while irradiating natural light to an adhesive label, the front surface of the adhesive label was observed first, without using an absorption type polarizing film. As a result, the region corresponding to the birefringent layer and the other region could not be distinguished. Next, the front surface of the pressure-sensitive adhesive label was observed through the absorption polarizing film while irradiating the pressure-sensitive adhesive label with natural light. As a result, the region corresponding to the birefringent layer and the other region could be seen as the bright part and the dark part, respectively. That is, the latent image could be visualized.

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. FIG. 3 is a perspective view schematically showing a reflective polarizing layer included in the laminate shown in FIGS. 1 and 2. FIG. 3 is a perspective view schematically showing a reflective polarizing layer included in the laminate shown in FIGS. 1 and 2. FIG. 5 is a cross-sectional view schematically showing a part of the reflective polarizing layer shown in FIGS. 3 and 4. FIG. 5 is an exploded perspective view schematically showing a part of the reflective polarizing layer shown in FIGS. 3 and 4. 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 figure which shows schematically the other 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 roughly the modification of the laminated body shown in FIG.1 and FIG.2. Sectional drawing along the XI-XI line of the laminated body shown in FIG. The top view which shows roughly the other modification of the laminated body shown in FIG.1 and FIG.2. Sectional drawing along the XIII-XIII line of the laminated body shown in FIG. 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 roughly an example of the labeled article containing the laminated body shown in FIG.1 and FIG.2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Laminate for identification, 11 ... Reflective polarizing layer, 12 ... Birefringent layer, 13a ... Light absorption layer, 13b ... Reflective layer, 14 ... Overcoat layer, 15 ... Print pattern, 20 ... Adhesive label, 21 ... Adhesive layer, 30 ... recording medium, 31 ... paper, 40 ... adhesive label, 41 ... adhesive layer, 100 ... article with label, 101 ... article, 200 ... verification tool, 200 '... transparent body, 300 ... light source, 400 ... observation person, AA1 ... area, AA2 ... area, A _F ... fast axis, A _R ... reflection axis, A _S ... slow axis, A _T ... transmission axis, A _T '... transmission axis, L _L1 ... linearly polarized light, L _L2 ... linearly polarized light, L _LP ... linearly polarized light, L _N ... natural light, L _P ... P-wave, L _S ... S wave.

Claims (8)

The first and second portions aligned in-plane direction of a reflection-type polarizing layer I containing, each of said first and second portions, the first light and the first light transmitting layer of birefringent A reflective polarizing layer formed by alternately laminating second light transmissive layers having different optical characteristics from the transmissive layer;
A birefringent layer located on the front side of the polarizing layer and facing the polarizing layer only at the position of the first portion;
An optically isotropic transparent layer covering the front surface of the polarizing layer and the birefringent layer;
A discriminating laminate comprising a convex pattern or a concave pattern as a diffractive structure for diffracting the light transmitted or reflected by the polarizing layer. A light reflecting layer facing the back surface of the polarizing layer, the diffractive structure being provided on one main surface, and having light transparency;
The laminate according to claim 1, further comprising a light absorption layer facing the back surface of the polarizing layer with the light reflection layer interposed therebetween.   The laminate according to claim 2, further comprising a light-transmitting colored layer disposed in front of the light reflecting layer.   An adhesive label comprising: the laminate according to any one of claims 1 to 3; and an adhesive layer supported on a back surface of the laminate.   The adhesive label according to claim 4, wherein the laminate is provided with a notch and / or a perforation.   The laminate according to any one of claims 1 to 3, wherein the laminate is embedded in the paper, an adhesive layer supported on one main surface of the paper, and a back surface facing the adhesive layer. An adhesive label characterized by comprising:   A recording medium comprising paper and the laminate according to any one of claims 1 to 3 embedded in the paper.   A labeled article comprising: an article whose authenticity is to be confirmed; and a laminate according to any one of claims 1 to 3 supported by the article whose authenticity is to be confirmed. .

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