JP2008070807A - Medium and label for preventing forgery, printed matter, transferring foil and discrimination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a medium for preventing forgery which can achieve a higher effect when used for preventing forgery and to provide a label for preventing forgery, printed matter, transferring foil and a discrimination method. <P>SOLUTION: The medium 10 for preventing forgery is provided with: a light reflecting layer 22; a λ/4 retardation layer 24 opposed to a part of the front surface of the light reflecting layer 22; and a λ/8 retardation layer 26 opposed to the other parts of the front surface of the light reflecting layer 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a forgery prevention technique that can be used to prevent forgery of securities such as stock certificates, bonds, checks, and gift certificates, lotteries, and ID cards.

  In recent years, copiers using electrophotographic technology have become widespread, and anyone can easily copy documents using this. In particular, according to a recent color digital copying machine, even a copy that is extremely difficult to determine whether it is a manuscript or a copy can be easily produced.

  A general color digital copying machine performs copying by the following method. First, the original is irradiated with light, and the reflected light is detected by a CCD line sensor. The CCD line sensor generates a digital signal corresponding to the intensity of the reflected light and transmits it to a memory in the copying machine. This reading is performed for three colors of red (R), green (G), and blue (B), and digital signals obtained for the respective colors are stored in the memory. Next, based on the stored digital signal, an electrostatic latent image is drawn on the photosensitive drum with a laser beam. Subsequently, a toner image corresponding to the electrostatic latent image is formed on the photosensitive drum using electrostatic force. Thereafter, the toner image is transferred to a sheet, and the transferred toner image is fixed on the sheet. For example, by performing this process for three colors, an elaborate color copy can be obtained.

  While such color copying is convenient, it facilitates the forgery of securities such as stock certificates, bonds, promissory notes, checks, and printed materials such as admission tickets and boarding passes. For this reason, various proposals have been made to take measures to prevent duplication of printed matter so that they cannot be easily copied.

  As one of such measures, there is a technique for making the color of a copy by color copying different from the color of an original. For example, a technique for coloring a document such as securities with a very light color has been proposed. It is difficult to accurately reproduce this light color by copying. In addition, a technique for forming halftone dots of different sizes has been proposed. In these copies, the reproducibility of small halftone dots tends to be insufficient. Further, a technique for printing in a color that is not found in toner of color copiers such as green, purple, orange, gold, and silver has been proposed. In addition, reflection and / or absorption characteristics are almost equal in the wavelength range of light that can be easily perceived by humans, and reflection and / or absorption in wavelength ranges of light that are difficult for humans to perceive, for example, wavelength ranges of 380 nm to 450 nm and 650 nm to 780 nm. Techniques using two types of inks having different characteristics have been proposed. The two areas formed using these inks are visually the same color, but can be reproduced in different colors when copied on a color copier.

  However, the color copying machine can correct the output color. Also, digital presses that correct digital data read by a color scanner with a computer and output the data with a color printer are becoming widespread. Therefore, if a little effort is required, it is possible to precisely reproduce the color of the document, and it is difficult to prevent forgery with the above-described technique.

  In addition, for example, a technique has been proposed in which securities are provided with special parts that cannot be reproduced by a color copying machine. Among these, the technique of providing an OVD (Optical Variable Device) such as a hologram foil described in Patent Documents 1 and 2 on the surface of securities or the like has already been put into practical use. According to this technique, since the silver surface of the hologram specularly reflects light, the reflected light does not enter the CCD line sensor, and the silver surface portion of the original is reproduced in black on the copy. Patent Document 3 describes a technique using an optical thin film in which ceramic layers having different refractive indexes are stacked and the color changes depending on the viewing angle. Since this color change cannot be obtained with a copy, it is possible to easily determine the authenticity. Furthermore, it has also been proposed to perform printing by crushing the thin film formed by this method and mixing fragments into ink.

  However, due to the development of embossing technology, the formation of a reflective layer including a relief-type diffractive structure is becoming more difficult than before. In addition, multilayer thin film has begun to be sold as a general packaging film. As a result, the effect of preventing forgery of holograms has been reduced.

  Patent Documents 4 to 7 describe the use of cholesteric liquid crystal in order to obtain an effect of changing the color of reflected light in accordance with the viewing angle, that is, a color shift effect, similarly to a hologram.

  The wavelength of circularly polarized light selectively reflected by the polymer cholesteric liquid crystal changes according to the angle formed by the line of sight and the helical axis. Patent Documents 4 to 7 disclose that this color shift effect is used in order to obtain an anti-counterfeit effect. Also disclosed are techniques for laminating a cholesteric liquid crystal layer and a hologram forming portion, and using an ink containing a cholesteric liquid crystal pigment and an ionizing radiation curable resin. Furthermore, there is a disclosure of a technique for controlling the rotation direction of polarized light as reflected light by combining a cholesteric liquid crystal layer and a phase difference layer using nematic liquid crystal.

However, nowadays cholesteric liquid crystals are easily available because of the frequent use of circularly polarizing plates in displays. Therefore, the anti-counterfeit effect by the cholesteric liquid crystal is decreasing.
JP-A-6-259013 Japanese Patent Laid-Open No. 7-089293 JP-T-2004-505158 JP-A-63-51193 International Publication No. 00/13065 Pamphlet JP 2002-114935 A JP 2002-255200 A

  An object of the present invention is to achieve a higher anti-counterfeit effect.

  A first invention for solving the above-described problems is a light reflecting layer, a λ / 4 retardation layer facing a part of the front surface of the light reflecting layer, and another one of the front surfaces of the light reflecting layer. The anti-counterfeit medium is provided with a λ / 8 phase difference layer facing the portion.

  Further, according to a second aspect of the present invention, the λ / 4 retardation layer and the λ / 8 retardation layer are adjacent to each other when viewed from the normal direction with respect to the front surface of the light reflecting layer. The anti-counterfeit medium according to the first aspect of the invention.

  According to a third aspect of the present invention, the front surface of the light reflecting layer includes first to third light reflecting regions, and the λ / 4 phase difference layer includes the first light in the first to third light reflecting regions. The anti-counterfeit medium according to the first aspect of the invention, wherein the medium is opposed to only the reflection region, and the λ / 8 retardation layer is opposed only to the second light reflection region of the first to third light reflection regions. is there.

  The fourth invention further includes a light-transmitting colored layer positioned in front of the light reflecting layer and facing the λ / 4 retardation layer and / or the λ / 8 retardation layer. The anti-counterfeit medium according to any one of the first to third aspects of the invention.

  In the fifth invention, the λ / 4 retardation layer and / or the λ / 8 retardation layer includes a light-transmitting colored layer and a pair of retardation layers sandwiching the colored layer. This is a forgery prevention medium according to any one of the first to third inventions.

  The sixth invention is the anti-counterfeit medium according to any one of the first to fifth inventions, wherein the light reflecting layer includes a reflecting layer exhibiting a structural color.

  The seventh invention is the anti-counterfeit medium according to any one of the first to fifth inventions, wherein the light reflecting layer includes a diffractive structure.

  According to an eighth aspect of the present invention, the λ / 4 retardation layer and / or the λ / 8 retardation layer is a polymer liquid crystal layer, and the alignment is interposed between the polymer liquid crystal layer and the light reflecting layer. The anti-counterfeit medium according to any one of the first to seventh inventions, further comprising a film.

  The ninth invention is a forgery prevention label comprising the forgery prevention medium of any one of the first to eighth inventions and an adhesive layer supported on the back surface thereof.

  According to a tenth aspect of the present invention, there is provided a printed matter comprising the forgery prevention medium according to any one of the first to eighth aspects and a paper into which the forgery prevention medium is inserted.

  An eleventh aspect of the invention is supported by any one of the first to eighth aspects of the anti-counterfeit medium, a base material that releasably supports the front surface of the anti-counterfeit medium, and a back surface of the anti-counterfeit medium. The transfer foil is characterized by including an adhesive layer.

  A twelfth aspect of the invention is a method for discriminating between an authentic product and a non-authentic product using a verification tool for an article of which authenticity is unknown or not. The verification tool is an article supporting any one of the anti-counterfeit media of the invention, wherein the verification tool faces a linearly polarizing film, one main surface of the linearly polarizing film, and a fast axis is a transmission axis of the linearly polarizing film. A λ / 4 phase difference layer having an angle of 45 ° with respect to the λ / 4 phase difference layer of the verification tool. Whether the first and second regions forming the latent image to be visualized or the visible image in which the contrast ratio is changed are overlapped with each other so as to face an unknown article whether or not it is authentic. If it is not contained in an unknown item, is it authentic? It is determined that the known article is non-authentic, and the article that is unknown whether or not it is authentic and the verification tool, the linear polarizing film of the verification tool and whether or not it is authentic. Lightness of each of the first area and the second area when the unknown article is observed through the verification tool in this state and the unknown article is observed through the verification tool. Is determined according to the direction of the transmission axis of the linearly polarizing film, the determination whether the authentic or unknown article is a non-authentic product. .

  According to the present invention, a higher forgery prevention effect can be achieved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals are given to components that exhibit the same or similar functions, and duplicate descriptions are omitted.

  FIG. 1 is a plan view schematically showing a forgery prevention medium according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II of the forgery prevention medium shown in FIG.

  The anti-counterfeit medium 10 includes a base material 21 shown in FIG. The base material 21 is a biaxially stretched film made of, for example, polyethylene terephthalate.

  A light reflection layer 22 is formed on the substrate 21. Typically, the light reflecting layer 22 is a specular reflector. The light reflecting layer 22 can be formed by evaporating aluminum, for example.

  The front surface of the light reflection layer 22 is covered with an alignment film 23. The alignment film 23 is made of, for example, polyvinyl alcohol (PVA). The alignment film 23 has a function of controlling the alignment direction of mesogenic groups of liquid crystal molecules included in the liquid crystal layer formed thereon.

The front surface of the alignment film 23 is partially covered with the λ / 4 retardation layer 24. The λ / 4 retardation layer 24 is made of, for example, nematic liquid crystal. The λ / 4 retardation layer 24 has a _fast axis along a direction indicated by an arrow n _A24 in FIG. 1 and a slow axis n _B24 (not shown in FIG. 1) perpendicular to the fast axis. ing. When the λ / 4 retardation layer 24 has a wavelength λ and linearly polarized light oblique to the polarization plane (electric field vector oscillation plane) is incident, the polarization plane is a first straight line parallel to the slow axis n _B24. The polarized light and the second linearly polarized light whose plane of polarization is parallel to the fast axis n _A24 and whose phase has advanced by λ / 4 from the first linearly polarized light are emitted.

On the front surface of the alignment film 23, the λ / 8 retardation layer 26 is adjacent to the λ / 4 retardation layer 24. The λ / 8 retardation layer 26 is made of, for example, nematic liquid crystal. The λ / 8 retardation layer 26 includes, for example, a _fast axis along a direction indicated by an arrow n _A26 in FIG. 1 and a slow axis n _B26 (not shown in FIG. 1) perpendicular to the fast axis. Have. The λ / 8 phase difference layer 26 has a wavelength of λ and a plane of polarization (oscillation plane of the electric field vector) is incident on linearly polarized light oblique to the fast axis n _A26 , and the plane of polarization is the slow axis n _B26. And a second linearly polarized light whose plane of polarization is parallel to the fast axis n _A26 and whose phase is advanced by λ / 8 from the first linearly polarized light.

  The wavelength λ is a design wavelength. The design wavelength λ is typically a wavelength of green light in which natural human light cells have high sensitivity, for example, about 550 nm. The retardation of the λ / 4 retardation layer 24 and the λ / 8 retardation layer 26 at the design wavelength λ may not be as designed due to variations in the thickness thereof. Even in such a case, if the deviation of the retardation from the design value is about 10% or less of the design value, the verification described later is not greatly affected.

In the present embodiment, for the sake of simplicity of explanation, it is assumed that the _fast axis n _{A24 of} the λ / 4 retardation layer 24 and the _fast axis n _{A26 of the} λ / 8 retardation layer 26 are parallel. The fast axis n _A24 and the fast axis n _A26 may be orthogonal to each other or may cross each other at an angle.

  The λ / 4 retardation layer 24 is covered with a light-transmitting colored layer 25. The colored layer 25 contains a dye such as a direct dye, a disperse dye, and a dichroic dye, or a pigment. The colored layer 25 can further contain a transparent resin. The colored layer 25 can be omitted.

  Hereinafter, of the front surface of the anti-counterfeit medium 10 or the light reflection layer 22, a portion corresponding to the λ / 4 retardation layer 24 is referred to as a first light reflection region 11, and a portion corresponding to the λ / 8 retardation layer 26 is referred to. This is called a second light reflection region 12.

  Next, an image that is seen when natural light is irradiated onto the anti-counterfeit medium 10 and observed with the naked eye will be described.

  Since the colored layer 25 absorbs part of the incident natural light, the first light reflecting region 11 emits light having a lower intensity than the incident light. On the other hand, the second light reflecting region 12 emits light having substantially the same intensity as the incident light. Therefore, the first light reflection region 11 looks darker than the second light reflection region 12. Further, the hue of the colored layer 25 can be seen in the first light reflection region 11.

  Next, a verification tool used for confirming that the article supporting the forgery prevention medium 10 is a genuine product will be described.

  FIG. 3 is an exploded view schematically showing an example of the verification tool. A verification tool 50 shown in FIG. 3 includes a linearly polarizing film 51 and a λ / 4 retardation layer 52.

  The linearly polarizing film 51 is, for example, an absorptive polarizing film. In this case, the linearly polarizing film 51 transmits linearly polarized light having a polarization plane parallel to the transmission axis OP, and absorbs linearly polarized light having a polarization plane orthogonal to the transmission axis OP.

  As the absorption-type polarizing film 51, for example, a PVA-iodine type film or a dichroic dye type film in which iodine is absorbed in a stretched film made of PVA can be used. Since these polarizing films have low physical strength, they may be used by being sandwiched between films made of triacetylrose (TAC).

The λ / 4 retardation layer 52 faces one main surface of the linearly polarizing film 51. The _fast axis n _A52 of the λ / 4 retardation layer 52 is oblique to the transmission axis OP of the linearly polarizing film 51. As an example, when the λ / 4 retardation layer 52 is viewed from the linearly polarizing film 51 side, the direction of the _fast axis n _A52 of the λ / 4 retardation layer 52 is counterclockwise from the direction parallel to the transmission axis OP. It is assumed that the direction is rotated by 45 °. In this case, the verification tool 50 functions as a left circular polarizer.

  The retardation of the λ / 4 retardation layer 52 at the design wavelength λ may not be as designed due to variations in the thickness thereof. Even in such a case, if the deviation of the retardation from the design value is about 10% or less of the design value, the verification described later is not greatly affected.

  Next, a method for verifying that the article supporting the forgery prevention medium 10 is an authentic product using the verification tool 50 will be described.

  4A is a plan view schematically showing an example of an image that can be observed when the anti-counterfeit medium 10 shown in FIGS. 1 and 2 and the verification tool 50 shown in FIG. 3 are overlapped.

In FIG. 4A, the forgery prevention medium 10 and the verification tool 50 are arranged such that the λ / 4 retardation layer 52 faces both the light reflection regions 11 and 12. Further, the light transmission axis OP of the linearly polarizing film 51 is orthogonal to both the _fast axis n _A24 of the λ / 4 retardation layer 24 and the _fast axis n _A26 of the λ / 8 retardation layer 26. In this case, as shown in FIG. 4A, the first light reflection region 11 appears as a bright portion, and the second light reflection region 12 appears as a dark portion.

  The reason why the first light reflection region 11 and the second light reflection region 12 can be seen as the bright portion and the dark portion by overlapping the verification tool 50 will be described. Here, for simplification, only light having a wavelength equal to the design wavelength λ is considered.

  First, the reflection by the first light reflection region 11 will be described.

  The left circularly polarized light emitted from the verification tool 50 enters the λ / 4 retardation layer 24 shown in FIG. The λ / 4 retardation layer 24 converts the incident left circularly polarized light into linearly polarized light having a polarization plane orthogonal to the transmission axis OP of the linearly polarizing film 51. The linearly polarized light is specularly reflected by the light reflecting layer 22. The reflected linearly polarized light is incident again on the λ / 4 retardation layer 24 and converted to left circularly polarized light. This left circularly polarized light enters the λ / 4 retardation layer 52 of the verification tool 50 and is converted into linearly polarized light having a polarization plane parallel to the transmission axis OP of the linearly polarizing film 51. This linearly polarized light is transmitted through the linearly polarizing film 51.

  Next, light reflection by the second light reflection region 12 will be described.

  The left circularly polarized light emitted from the verification tool 50 enters the λ / 8 phase difference layer 26 shown in FIG. The λ / 8 retardation layer 26 converts the incident left circularly polarized light into left elliptically polarized light. The left elliptical polarized light emitted from the λ / 8 retardation layer 26 is specularly reflected by the light reflecting layer 22 and converted into right elliptical polarized light. The right elliptically polarized light is incident on the λ / 8 retardation layer 26 and converted to right circularly polarized light. This right circularly polarized light enters the λ / 4 retardation layer 52 of the verification tool 50 and is converted into linearly polarized light having a polarization plane orthogonal to the transmission axis OP of the linearly polarizing film 51. This linearly polarized light cannot pass through the linearly polarizing film 51.

  For the above reasons, the first light reflection region 11 appears as a bright portion, and the second light reflection region 12 appears as a dark portion.

  FIGS. 4B to 4D are planes schematically showing other examples of images that can be observed when the anti-counterfeit medium 10 shown in FIGS. 1 and 2 and the verification tool 50 shown in FIG. 3 are overlapped. FIG. 4 (b) to 4 (d) respectively show a state in which only the verification tool 50 is rotated 45 °, 90 ° and 135 ° clockwise as viewed from the observer side from the state shown in FIG. 4 (a). Is drawn.

  As shown in FIGS. 4A to 4D, the brightness of the first light reflection area 11 and the brightness of the second light reflection area 12 change even when the verification tool 50 is rotated around the normal line. do not do. This is because the light emitted from the λ / 4 retardation layer 52 to the anti-counterfeit medium 10 is circularly polarized light, and the light emitted from the first light reflection region 11 and the second light reflection region 12 toward the verification tool 50 is also circular. This is because it is polarized light.

  As described above, when the anti-counterfeit medium 10 is observed without using the verification tool 50, the colored layer 25 causes a difference in brightness between the first light reflection region 11 and the second light reflection region 12. Specifically, when the forgery prevention medium 10 is observed without using the verification tool 50, the first light reflection region 11 and the second light reflection region 12 form a visible image corresponding to the colored layer 25. Then, the verification tool 50 and the anti-counterfeit medium 10 are arranged so that the λ / 4 retardation layer 52 and the anti-counterfeit medium 10 face each other, and the anti-counterfeit medium 10 is observed through the verification tool 50 in this state. The 1 light reflection area | region 11 appears as a bright part, and the 2nd light reflection area | region 12 appears as a dark part. That is, the use of the verification tool 50 increases the contrast ratio between the first light reflection region 11 and the second light reflection region 12.

  When the colored layer 25 is omitted from the forgery prevention medium 10, the first light reflection area 11 and the second light reflection area 12 are discriminated when the forgery prevention medium 10 is observed without using the verification tool 50. It is difficult. That is, the first light reflection area 11 and the second light reflection area 12 form a latent image. In this latent image, the verification tool 50 and the anti-counterfeit medium 10 are arranged so that the λ / 4 retardation layer 52 and the anti-counterfeit medium 10 face each other, and the anti-counterfeit medium 10 is observed through the verification tool 50 in this state. To visualize.

  Next, an image that is seen when the verification tool 50 is turned over and superimposed on the forgery prevention medium 10 will be described.

FIG. 5A is a plan view schematically showing another example of an image that can be observed when the anti-counterfeit medium 10 shown in FIGS. 1 and 2 and the verification tool 50 shown in FIG. 3 are overlapped. In FIG. 5A, the verification tool 50 is turned over, the transmission axis OP of the linearly polarizing film 51, the _fast axis n _{A24 of the} λ / 4 phase difference layer 24, and the _fast axis of the λ / 8 phase difference layer 26. n _A26 is orthogonally crossed.

  When the verification tool 50 is turned upside down, the verification tool 50 functions as a linear polarizer having a transmission axis OP. In other words, when the verification tool 50 is irradiated with natural light from the λ / 4 phase difference layer 52 side, the verification tool 50 has a linearly polarized light having a polarization plane parallel to the transmission axis OP of the linear polarization film 51 toward the forgery prevention medium 10. Release.

  When the anti-counterfeit medium 10 and the verification tool 50 are arranged as shown in FIG. 5A, the first light reflection region 11 is placed on the anti-counterfeit medium 10 and the verification tool 50 as shown in FIGS. It looks almost the same brightness as the case where the arrangement shown in FIG. On the other hand, the 2nd light reflection area | region 12 looks brighter compared with the case where the arrangement | positioning shown to Fig.4 (a)-(d) is employ | adopted for the forgery prevention medium 10 and the verification tool 50. FIG. Hereinafter, the reason why both the first light reflection region 11 and the second light reflection region 12 of the anti-counterfeit medium 10 appear bright will be described.

First, the reflection by the first light reflection region 11 will be described. The linearly polarized light incident on the λ / 4 retardation layer 24 of the first light reflection region 11 has a polarization plane orthogonal to the fast axis n _A24 of the λ / 4 retardation layer 24. Therefore, this linearly polarized light is transmitted through the λ / 4 retardation layer 24 as linearly polarized light having a polarization plane parallel to the transmission axis OP of the linearly polarizing film 51. The linearly polarized light emitted from the λ / 4 retardation layer 24 is specularly reflected by the light reflecting layer 22. The reflected linearly polarized light is incident on the λ / 4 retardation layer 24 again, and for the same reason as described above, the λ / 4 retardation layer 24 remains linearly polarized light having a polarization plane parallel to the transmission axis OP of the polarizing film 51. Transparent. The linearly polarized light is transmitted through the linearly polarizing film 51 without being absorbed ideally. The linearly polarized light transmitted through the linearly polarizing film 51 enters the λ / 4 retardation layer 52 and is converted into left circularly polarized light. Thus, the verification tool 50 ideally transmits all of the reflected light from the first light reflection region 11.

Next, reflection by the second light reflection region 12 will be described. The linearly polarized light incident on the λ / 8 retardation layer 26 of the second light reflecting region 12 has a polarization plane orthogonal to the fast axis n _A26 of the λ / 8 retardation layer 26. Therefore, this linearly polarized light is transmitted through the λ / 8 retardation layer 26 as linearly polarized light having a polarization plane parallel to the transmission axis OP of the linearly polarizing film 51. The linearly polarized light emitted from the λ / 8 retardation layer 26 is specularly reflected by the light reflecting layer 22. The reflected linearly polarized light is incident on the λ / 8 retardation layer 26 again, and is transmitted through the λ / 8 retardation layer 26 as linearly polarized light having a polarization plane parallel to the transmission axis OP of the linearly polarizing film 51. The linearly polarized light is transmitted through the linearly polarizing film 51 without being absorbed ideally. The linearly polarized light transmitted through the linearly polarizing film 51 enters the λ / 4 retardation layer 52 and is converted into left circularly polarized light. Thus, the verification tool 50 ideally transmits all of the reflected light from the second light reflection region 12.

  For the above reasons, when the arrangement shown in FIG. 5A is adopted, both the first light reflection region 11 and the second light reflection region 12 appear bright. The first light reflection region 11 includes a colored layer 25 unlike the second light reflection region 12. Therefore, when the arrangement shown in FIG. 5A is adopted, the second light reflection region 12 looks brighter than the first light reflection region 11.

FIG. 5B is a plan view schematically showing still another example of an image that can be observed when the anti-counterfeit medium 10 shown in FIGS. 1 and 2 and the verification tool 50 shown in FIG. 3 are overlapped. . FIG. 5B illustrates a state in which only the verification tool 50 is rotated 45 ° clockwise as viewed from the observer side from the state illustrated in FIG. That is, in the arrangement of FIG. 5B, the optical axis OP of the linearly polarizing film 51 and the _fast axis n _{A24 of the} λ / 4 retardation layer 24 and the _fast axis n _{A26 of the} λ / 8 retardation layer 26 are 45. It has an angle of °. Further, the _fast axis n _A52 of the λ / 4 retardation layer 52 of the verification tool 50 is parallel to the _fast axis n _{A24 of the} λ / 4 retardation layer 24 and the _fast axis n _{A26 of the} λ / 8 retardation layer 26. It is.

  When the anti-counterfeit medium 10 and the verification tool 50 are arranged as shown in FIG. 5B, the first light reflection area 11 appears as a dark part, and the second light reflection area 12 is compared with the first light reflection area 11. Therefore, it looks brighter and darker than the second light reflection region 12 when the arrangement of FIG. 5A is adopted. Here, the reason for causing such a change in brightness will be described.

When the arrangement of FIG. 5B is adopted, the vibration direction of the electric field vector of linearly polarized light incident on the λ / 4 retardation layer 24 of the first light reflection region 11 is λ // when viewed from the anti-counterfeit medium 10 side. This is the direction rotated 45 ° clockwise from the direction parallel to the _fast axis n _A24 of the four retardation layer 24. Therefore, this linearly polarized light is converted into right circularly polarized light by the λ / 4 retardation layer 24. The right circularly polarized light becomes left circularly polarized light by being reflected by the light reflecting layer 22. The reflected left circularly polarized light is converted into linearly polarized light by the λ / 4 retardation layer 24. Since this linearly polarized light has a polarization plane orthogonal to the transmission axis OP of the linearly polarizing film 51, it cannot be transmitted through the linearly polarizing film 51.

On the other hand, the oscillation direction of the electric field vector of the linearly polarized light incident on the λ / 8 retardation layer 26 of the second light reflection region 12 is also the fast axis n of the λ / 8 retardation layer 26 when viewed from the forgery prevention medium 10 side. _This is the direction rotated 45 ° clockwise from the direction parallel to _A26 . Therefore, this linearly polarized light is converted into right elliptically polarized light by the λ / 8 retardation layer 26. The right elliptical polarized light becomes left elliptical polarized light by being reflected by the light reflecting layer 22. This left elliptically polarized light is converted into left circularly polarized light by the λ / 8 retardation layer 26. This left circularly polarized light is incident on the linearly polarizing film 51. Of the left circularly polarized light incident on the linearly polarizing film 51, the linearly polarized light component having a polarization plane parallel to the transmission axis OP of the linearly polarized light film 51 is transmitted through the linearly polarized light film 51, and the other light components are transmitted by the linearly polarized light film 51. Absorbed. The transmitted linearly polarized light is converted into left circularly polarized light by the λ / 4 retardation layer 52.

  As described above, when the arrangement of FIG. 5B is adopted, the verification tool 50 absorbs almost all of the reflected light from the first light reflection region 11 and about the reflected light from the second light reflection region 12. Absorb half. Accordingly, the first light reflection region 11 appears as a dark portion, the second light reflection region 12 is brighter than the first light reflection region 11, and the second light reflection when the arrangement of FIG. 5A is adopted. It looks darker compared to region 12.

FIG. 5C is a plan view schematically showing still another example of an image that can be observed when the anti-counterfeit medium 10 shown in FIGS. 1 and 2 and the verification tool 50 shown in FIG. 3 are overlapped. . FIG. 5C illustrates a state in which only the verification tool 50 is rotated 90 ° clockwise as viewed from the observer side from the state illustrated in FIG. That is, in the arrangement of FIG. 5C, the transmission axis OP of the linearly polarizing film 51 and the _fast axis n _{A24 of the} λ / 4 retardation layer 24 and the _fast axis n _{A26 of the} λ / 8 retardation layer 26 are parallel. It is.

  When the arrangement shown in FIG. 5C is adopted, the first light reflection region 11 looks the same brightness as when the arrangement shown in FIG. 5A is adopted. Further, when the arrangement shown in FIG. 5C is adopted, the second light reflection region 12 looks the same brightness as when the arrangement shown in FIG. 5A is adopted.

FIG. 5D is a plan view schematically showing still another example of an image that can be observed when the anti-counterfeit medium 10 shown in FIGS. 1 and 2 and the verification tool 50 shown in FIG. 3 are overlapped. . FIG. 5D illustrates a state in which only the verification tool 50 is rotated 135 ° clockwise as viewed from the observer side from the state illustrated in FIG. That is, in the arrangement of FIG. 5D, the optical axis OP of the linearly polarizing film 51 and the _fast axis n _{A24 of the} λ / 4 retardation layer 24 and the _fast axis n _{A26 of the} λ / 8 retardation layer 26 are 45. It has an angle of °. Further, the _fast axis n _A52 of the λ / 4 retardation layer 52 of the verification tool 50 is orthogonal to the _fast axis n _{A24 of the} λ / 4 retardation layer 24 and the _fast axis n _{A26 of the} λ / 8 retardation layer 26. is doing.

  When the arrangement shown in FIG. 5D is adopted, the first light reflection region 11 looks the same brightness as when the arrangement shown in FIG. 5B is adopted. Further, when the arrangement shown in FIG. 5D is adopted, the second light reflection region 12 looks the same brightness as when the arrangement shown in FIG. 5B is adopted.

  As is clear from the above description, the anti-counterfeit medium 10 and the verification tool 50 are overlapped so that the linearly polarizing film 51 and the anti-counterfeit medium 10 face each other, and the anti-counterfeit medium 10 is passed through the verification tool 50 in this state. When observed, the brightness of each of the first light reflection region 11 and the second light reflection region 12 changes according to the direction of the transmission axis OP of the linearly polarizing film 51.

  Further, when the anti-counterfeit medium 10 and the verification tool 50 are arranged so that the first light reflection region 11 looks brightest as shown in FIGS. 5A and 5C, the second light reflection region 12 is also formed. Looks brightest. However, in this case, due to light absorption by the colored layer 25, the first light reflection region 11 looks darker than the second light reflection region 12. In other words, when this arrangement is adopted using the forgery prevention medium 10 in which the colored layer 25 is omitted, the first light reflection region 11 and the second light reflection region 12 appear to have almost the same brightness.

  When the anti-counterfeit medium 10 and the verification tool 50 are arranged so that the first light reflection area 11 looks darkest as shown in FIGS. 5B and 5D, the second light reflection area 12 is also Looks darkest. However, in this case, the second light reflection region 12 looks brighter than the first light reflection region 11. Note that these brightnesses hardly change even if the colored layer 25 is omitted from the forgery prevention medium 10.

  The anti-counterfeit medium 10 is supported on an article to be confirmed to be authentic. Even when it is not possible to discriminate between such an article with anti-counterfeit measures and a non-authentic product such as a counterfeit product with the naked eye, it is possible to discriminate them by using the verification tool 50, for example. For example, when the above-described image is not displayed when observing an article whose authenticity is unknown by the method described with reference to FIGS. 4 to 5, it is determined that the article is non-genuine. be able to. The change in the display image according to the arrangement of the forgery prevention medium 10 and the verification tool 50 cannot be reproduced with a copy of the forgery prevention medium 10. Further, it is difficult to copy the forgery prevention medium 10. Therefore, when the anti-counterfeit medium 10 is used, a higher anti-counterfeit effect can be achieved.

  Next, another embodiment of the present invention will be described.

  FIG. 6 is a plan view schematically showing a forgery prevention medium according to the second embodiment of the present invention. 7 is a cross-sectional view of the forgery prevention medium shown in FIG. 6 taken along line VII-VII.

  The forgery prevention medium 10 is the same as the forgery prevention medium 10 described with reference to FIGS. 1 and 2 except that the following configuration is adopted. That is, in the anti-counterfeit medium 10 shown in FIGS. 6 and 7, the λ / 8 retardation layer 26 is separated from the λ / 4 retardation layer 24. In other words, in the forgery prevention medium 10, the third light reflection region 13 is provided in addition to the first light reflection region 11 and the second light reflection region 12.

  The third light reflection region 13 is a portion of the anti-counterfeit medium 10 other than the first light reflection region 11 and the second light reflection region 12 or the front surface of the light reflection layer 22 with a λ / 4 retardation layer 24 and λ. / 8 This is a portion that does not face the retardation layer 26. There may be no layer in front of the light reflecting layer 13 at the position of the third light reflecting region 13. Alternatively, an optically isotropic layer such as an alignment film 23 shown in FIGS. 6 and 7 may be formed in front of the light reflecting layer 13 at the position of the third light reflecting region 13. Good.

  Next, an image that is seen when natural light is irradiated onto the anti-counterfeit medium 10 and observed with the naked eye will be described.

  As described in the first embodiment, the first light reflection region 11 emits light having a lower intensity than the incident light because part of the incident natural light is absorbed by the colored layer 25. Further, the second light reflecting region 12 emits light whose intensity is substantially equal to the incident light. Further, the third light reflecting region 13 also emits light having an intensity substantially equal to the incident light. Therefore, when the forgery prevention medium 10 is irradiated with natural light and observed with the naked eye, the first light reflection region 11 is darker than the second light reflection region 12 and the third light reflection region 13. appear. Further, the hue of the colored layer 25 can be seen in the first light reflection region 11.

  Next, an image displayed when the anti-counterfeit medium 10 is observed using the verification tool 50 shown in FIG. 3 will be described.

  FIG. 8A is a plan view schematically showing an example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 6 and 7 and the verification tool shown in FIG. 3 are overlapped.

In FIG. 8A, the anti-counterfeit medium 10 and the verification tool 50 are arranged such that the λ / 4 retardation layer 52 faces the light reflection regions 11 to 13. Further, the light transmission axis OP of the linearly polarizing film 51 is orthogonal to both the _fast axis n _A24 of the λ / 4 retardation layer 24 and the _fast axis n _A26 of the λ / 8 retardation layer 26. In this case, as described with reference to FIG. 4A, the first light reflection region 11 appears as a bright portion. And the 2nd light reflection area | region 12 appears as a dark part.

  Further, as described above, when the verification tool 50 is irradiated with natural light, the λ / 4 retardation layer 52 emits left circularly polarized light. The third light reflection region 13 converts left circularly polarized light into right circularly polarized light. That is, the reflected light from the third light reflection region 13 that enters the λ / 4 retardation layer 52 is right circularly polarized light. This right circularly polarized light cannot pass through the verification tool 50. Therefore, the third light reflection region 13 appears as a dark part.

  FIGS. 8B to 8D are planes schematically showing other examples of images that can be observed when the anti-counterfeit medium 10 shown in FIGS. 6 and 7 and the verification tool 50 shown in FIG. 3 are overlapped. FIG. FIGS. 8B to 8D show states in which only the verification tool 50 is rotated 45 °, 90 ° and 135 ° clockwise as viewed from the observer side from the state shown in FIG. 8A. Is drawn.

  As shown in FIGS. 8A to 8D, the brightness of the first light reflection area 11, the brightness of the second light reflection area 12, and the brightness of the third light reflection area 13 are determined by the verification tool 50. Even if it is rotated around the normal, it does not change. This is because the light emitted from the λ / 4 retardation layer 52 to the anti-counterfeit medium 10 is circularly polarized light, and the light emitted from the light reflecting regions 11 to 13 toward the verification tool 50 is also circularly polarized light.

  Next, an image that is seen when the verification tool 50 is turned over and superimposed on the forgery prevention medium 10 will be described.

FIG. 9A is a plan view schematically showing another example of an image that can be observed when the forgery prevention medium shown in FIGS. 6 and 7 and the verification tool shown in FIG. 3 are overlapped. In FIG. 9A, the verification tool 50 is turned over, the transmission axis OP of the linearly polarizing film 51, the _fast axis n _{A24 of the} λ / 4 phase difference layer 24, and the _fast axis of the λ / 8 phase difference layer 26. n _A26 is orthogonally crossed.

  In this case, the first light reflection region 11 and the second light reflection region 12 appear with the same brightness as described with reference to FIG. When the verification tool 50 is turned upside down, the verification tool 50 functions as a linear polarizer having a transmission axis OP. Therefore, the third light reflection region 13 appears as a bright part.

  FIGS. 9B to 9D schematically show still other examples of images that can be observed when the anti-counterfeit medium 10 shown in FIGS. 6 and 7 and the verification tool 50 shown in FIG. 3 are overlapped. FIG. 9 (b) to 9 (d) show states in which only the verification tool 50 is rotated 45 °, 90 ° and 135 ° clockwise as viewed from the observer side from the state shown in FIG. 9 (a). Is drawn.

  When the arrangement shown in FIGS. 9B to 9D is adopted, the first light reflection region 1 and the second light reflection region 12 have been described with reference to FIGS. 5B to 5D. It looks at the same brightness. Further, the third light reflection region 13 appears with the same brightness as described with reference to FIG. That is, the brightness of the third light reflection region 13 does not change even when the verification tool 50 is rotated.

  When this anti-counterfeit medium 10 is supported by an article to be confirmed to be authentic, it is possible to discriminate between genuine and non-authentic products by the same method as described in the first embodiment. In addition, as described above, the change of the image displayed in the third light reflection region 13 according to the arrangement of the forgery prevention medium 10 and the verification tool 50 is different from the image displayed in the first light reflection region 11 and the second light reflection. This is different from the change in the image displayed in the region 12. Therefore, when an article whose identity is unknown or not does not cause the image change described above with respect to the third light reflection region 13, it can be determined that the article is a non-authentic product. Therefore, the use of this reduces the probability that a non-genuine product is erroneously determined to be a genuine product.

  The anti-counterfeit medium 10 described with reference to FIGS. 6 and 7 has a more complicated structure than the anti-counterfeit medium 10 described with reference to FIGS. Therefore, the anti-counterfeit medium 10 is more difficult to duplicate. Therefore, when this anti-counterfeit medium 10 is used, a higher anti-counterfeit effect can be achieved.

  Various modifications can be made to the forgery prevention medium 10 described above. For example, although the colored layer 25 covers the λ / 4 retardation layer 25 in FIG. 2, the colored layer 25 may be disposed between the λ / 4 retardation layer 24 and the reflective layer 22. Alternatively, the λ / 4 retardation layer 24 may be composed of the colored layer 25 and a pair of retardation layers sandwiching it. The colored layer 25 may cover the λ / 8 retardation layer 26 or may be disposed between the λ / 8 retardation layer 26 and the reflective layer 22. Alternatively, the λ / 8 retardation layer 26 may be composed of the colored layer 25 and a pair of retardation layers sandwiching it. A colored layer 25 may be provided around these retardation layers 24 and 26.

  A plurality of colored layers 25 having different hues may be arranged. In this case, these colored layers 25 may be formed on the same substrate or may be formed on different substrates. For example, a structure in which a certain colored layer 25 is formed on the reflective layer 22 and another colored layer 25 is sandwiched between the λ / 4 retardation layer 24 and / or the λ / 8 retardation layer 26 with a pair of retardation layers. It may be adopted.

  The light reflecting layer 24 may include a diffractive structure. For example, the light reflection layer 24 may be a metal reflection layer having a relief structure.

  The light reflection layer 24 may include a reflection layer exhibiting an interference color. In this case, as the light reflection layer 24, a reflection layer exhibiting an interference color may be used alone, or a laminate of a reflection layer exhibiting an interference color and a metal reflection layer may be used. As the reflective layer exhibiting an interference color, for example, a layer formed using a cholesteric liquid crystal layer and a pearl pigment can be used.

  A protective layer may be provided on the front surface of the anti-counterfeit medium 10 for the purpose of protection from ultraviolet rays and physical impact.

  Instead of the verification tool 50 that functions as a left circular polarizer, a verification tool 50 that functions as a right circular polarizer may be used. Further, instead of stacking the verification tool 50 upside down and stacking on the forgery prevention medium 10, a separately prepared linear polarizing film may be stacked on the forgery prevention medium 10.

  The back surface of the anti-counterfeit medium 10, here, the surface on which the reflective layer 22 is not formed, of the two main surfaces of the base material 21 may be subjected to adhesion or adhesion processing. That is, an adhesive label that can be used as an anti-counterfeit label may be formed using the anti-counterfeit medium 10.

  The anti-counterfeit medium 10 can be applied to printed matter by various methods. For example, you may affix said adhesive label on printed matter. In this case, the base material 21 may be provided with cuts or perforations. In other words, a structure may be employed in which the base material 21 is broken from the notch or at the position of the perforation when the label is to be peeled off. Of course, the forgery prevention medium 10 can also be affixed to articles other than printed matter.

  A transfer foil containing the anti-counterfeit medium 10 may be formed and used to attach the anti-counterfeit medium 10 to the article.

  FIG. 10 is a cross-sectional view schematically showing an example of a transfer foil. A transfer foil 90 shown in FIG. 10 includes a base material 91. On the base material 91, a peeling layer 92, an anti-counterfeit medium 10, and an adhesive layer 93 are sequentially laminated.

  The front surface of the anti-counterfeit medium 10 faces the base material 91. The forgery prevention medium 10 may not include the base material 21 described with reference to FIG.

  When the anti-counterfeit medium 10 is applied to a printed matter, it may be cut into paper in a form called a thread (also called a strip, a filament, a thread, a safety strip, or the like).

  Hereinafter, materials that can be used for the anti-spoofing medium 10 will be described.

  Examples of the base material 21 include a synthetic resin film made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, polystyrene, and the like. Resin film, synthetic paper, paper, glass plate, aluminum foil, and the like can be used alone or in combination as a composite. The thickness may be appropriately selected according to the purpose of use of the forgery prevention medium 10.

  The material used for the light reflecting layer 22 is not particularly limited as long as light reflectivity is obtained. For example, a metal or an alloy such as aluminum, gold, silver, or copper can be used. These materials can be used alone or laminated. The light reflecting layer 22 can be formed using a method such as vacuum deposition or sputtering, for example. The thickness of the light reflection layer 22 is, for example, in the range of 50 to 1000 mm.

  As a material of the alignment film 23, for example, a resin such as polyvinyl alcohol (PVA) or polyimide can be used. A resin solution in which these resins are appropriately dissolved is applied onto the light reflecting layer 22 by using a coating method such as wire bar, gravure, or micro gravure, and this coating film is dried. After drying, a rubbing process is performed in which the alignment film surface is rubbed with a rubbing cloth to obtain an alignment film 23. Materials such as cotton and velvet can be used for the rubbing cloth.

  The λ / 4 retardation layer 24 and the λ / 8 retardation layer 26 formed on the alignment film 23 are, for example, a smectic liquid crystal or a nematic liquid crystal. In this case, the λ / 4 retardation layer 24 and the λ / 8 retardation layer 26 are made of, for example, a thermotropic liquid crystal material or a polymer liquid crystal material.

  For example, when a retardation layer made of a thermotropic liquid crystal material is formed, a printing pattern is formed using ink containing the retardation layer. For this printing, for example, a method such as a gravure printing method can be used. Moreover, the previous ink may further contain, for example, a solvent and / or an additive. Next, heat and / or pressure are applied to the printed pattern as necessary. Thereby, the retardation layers 24 and 26 are obtained. In addition, when using a thermotropic liquid crystal material, the alignment film 23 may be omitted.

  When forming a retardation layer made of a polymer liquid crystal material, for example, a printing pattern is formed on the alignment film 23 using an ink containing a polymerizable liquid crystal material. For this printing, for example, a method such as a gravure printing method can be used. Moreover, the previous ink may further contain, for example, a solvent and / or an additive. Next, the polymerizable liquid crystal material is polymerized by heating or energy beam irradiation. Thereby, the retardation layers 24 and 26 are obtained.

  As the polymerizable liquid crystal material, for example, an energy ray curable compound having a polymerizable group, a polycondensable group, or a group effective for polyaddition can be used. In this case, the polymerizable liquid crystal material preferably contains a monomer or oligomer having two or more energy ray-curable groups in the molecule. For example, polyfunctional monomers such as trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, or polyurethane polyacrylate, epoxy resin system Polyfunctional oligomers such as polyacrylate and acrylic polyol polyacrylate may be used. Alternatively, alkyl (C1-C18) (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, alkylene (C2-C4) glycol (meth) acrylate, alkoxy (C1-C10) alkyl (C2-C4) ( Monofunctional monomers such as (meth) acrylate, polyalkylene (C2-C4) glycol (meth) acrylate, alkoxy (C2-C10) polyalkylene (C2-C4) glycol (meth) acrylate may be used. . Alternatively, a cationic photopolymerizable monomer such as an aromatic epoxy compound, an alicyclic epoxy compound, or a glycidyl ester compound may be used. Those in which a functional group such as an acryl group is introduced into the terminal of the liquid crystal are more preferable because the physical strength is improved by crosslinking by irradiation with activated energy rays after the alignment of the liquid crystal is completed.

  The polymerizable liquid crystal material is typically used by adding a polymerization initiator or the like. For example, a polymerization initiator such as α-hydroxyacetophenone-based, α-aminoacetophenone-based acetophenone-based, benzoin ether-based, benzyl ketal-based, α-dicarbonyl-based, α-acyl oxime ester-based is added to the polymerizable liquid crystal material. May be.

  The retardation layers 24 and 26 may contain dyes such as direct dyes, disperse dyes and dichroic dyes, or pigments. In this case, the content of the colorant is adjusted so that the lightness L * in the ULCS (uniform lightness chromaticness scale) color system of the retardation layer is preferably 25 or more, more preferably 35 or more.

  Between the reflective layer 22 and the λ / 4 retardation layer 24 and / or the λ / 8 retardation layer 26, a layer containing a powder obtained by pulverizing a dielectric multilayer film and a resin may be provided. . The color of the dielectric multilayer film changes depending on the viewing angle. Therefore, a new optical characteristic can be given to the anti-counterfeit medium 10 by using a layer containing a powder obtained by pulverizing this.

  A general material can be used as the adhesive for applying the forgery prevention medium 10 to a printed matter or the like. For example, an adhesive such as vinyl chloride-vinyl acetate copolymer, polyester polyamide, acrylic, butyl rubber, natural rubber, silicon, polyisobutyl, etc. can be used alone, or these adhesives can be used. Aggregating components such as alkyl methacrylates, vinyl esters, acrylonitrile, styrene, vinyl monomers, unsaturated carboxylic acids, hydroxy group-containing monomers, modifying components such as acrylonitrile, polymerization initiators, plasticizers, curing agents, curing What added additives, such as an accelerator and antioxidant, as needed can also be used. For the formation of the adhesive layer, for example, a printing method such as a gravure printing method, an offset printing method, a screen printing method, or a coating method such as a bar coating method, a gravure method, or a roll coating method can be used. Or you may use the separator which formed the adhesion layer in one main surface. That is, the adhesive layer may be attached to the anti-counterfeit medium 10 together with the separator, and then only the separator may be peeled off from the anti-counterfeit medium 10. You may affix the release paper and release film which performed the release process to the adhesion layer. Thereby, handling of the forgery prevention medium 10 which gave the adhesive process becomes easy.

  Examples of the present invention will be described below.

(Example 1)
A single-sided aluminum vapor-deposited polyethylene terephthalate film having a thickness of 25 μm was prepared, and the alignment film ink was applied to the entire surface of the aluminum vapor-deposited surface using a bar coating method. This coating film was formed so that the dry film thickness was 2 μm. The composition of this alignment film ink is shown below.

PVA resin (trade name: Poval 117, Kuraray Co., Ltd.) 10% by weight
Solvent (mixture of 95 parts by weight of water and 5 parts by weight of isopropyl alcohol) 90% by weight
After the coating film was dried at 100 ° C. for 2 minutes, the coating film was rubbed. As the rubbing cloth, FINE PUFF YA-20-R manufactured by Yoshikawa Chemical Co., Ltd. was used. Thereby, an alignment film was obtained.

  Next, in order to form a λ / 8 retardation layer, a liquid crystal layer ink having the following composition was gravure-printed on the alignment film so as to have a cured film thickness of about 0.5 μm.

Liquid crystal (trade name: Paliocolor LC242 manufactured by BASF Corp.) 30% by weight
Polymerization initiator (trade name: Doluca 184, Ciba Kaigie Co., Ltd.) 1.5% by weight
Solvent (mixture of 50 parts by weight toluene and 50 parts by weight methyl ethyl ketone) 68.5% by weight
After this coating film was dried at 100 ° C. for 1 minute, it was irradiated with light of 500 mJ / cm ^{2 with} a high-pressure mercury lamp to cure the coating film. Thereby, a λ / 8 retardation layer was obtained.

  Next, in order to form a λ / 4 phase difference layer adjacent to the λ / 8 phase difference layer, the liquid crystal layer ink is cured on the alignment layer so as to have a cured film thickness of about 1 μm using a flat table calibrator. Gravure printed. The composition of this ink was the same as that of the liquid crystal layer ink used for forming the λ / 4 retardation layer except that the content of the liquid crystal and the polymerization initiator was doubled. This coating film was dried and cured in the same manner as described for the λ / 8 retardation layer to obtain a λ / 4 retardation layer.

  Next, in order to form a colored layer, a solution having the following composition was subjected to gravure printing on the λ / 4 retardation layer using a flat table calibrator so that the dry film thickness was 1 μm.

Polyester resin (trade name: Byron 300, manufactured by Toyobo Co., Ltd.) 20% by weight
Dye (trade name: Kayaset Flavine FG Nippon Kayaku Co., Ltd.) 1% by weight
Solvent (mixture of 50 parts by weight toluene and 50 parts by weight methyl ethyl ketone) 79% by weight
Next, this coating film was subjected to drying at 80 ° C. for 30 seconds. Thereby, a colored layer was obtained.
The anti-counterfeit medium was manufactured as described above.

  When this anti-counterfeit medium was observed with the naked eye while irradiating white light, the hue of the colored layer was confirmed in the region corresponding to the colored layer. Further, the area around the colored layer appeared white.

  Next, the counterfeit prevention medium 50 and the verification tool 50 described with reference to FIG. 3 are counterfeited under the same conditions as described above except that the retardation layer 52 faces the anti-counterfeit medium. The image prevention medium was observed. As a result, the region where the λ / 4 retardation layer was formed in the anti-counterfeit medium appeared as a bright portion, and the region where the λ / 8 retardation layer was formed as a dark portion.

  Next, the anti-counterfeit medium was observed under the same conditions as described above except that the anti-counterfeit medium and the verification tool 50 were stacked so that the linearly polarizing film 51 faced the anti-counterfeit medium. When the orientation direction of the mesogen group contained in the λ / 4 retardation layer and the λ / 8 retardation layer of the anti-counterfeit medium and the transmission axis OP of the linearly polarizing film 51 are parallel or orthogonal, the λ / 4 position of the anti-counterfeit medium Reflected light from the region where the phase difference layer was formed and the region where the λ / 8 phase difference layer was formed could be observed. However, when the angle formed by the orientation direction of the mesogen group contained in the λ / 4 retardation layer and the λ / 8 retardation layer of the anti-counterfeit medium and the transmission axis OP of the polarizing film 51 is 45 °, λ of the anti-counterfeit medium The region where the / 4 retardation layer was formed changed to a dark part. At this time, the region where the λ / 8 retardation layer was formed was also darker, but brighter than the region where the λ / 4 retardation layer was formed.

  Next, this anti-counterfeit medium was color copied and verified by the same method as described above using a verification tool. As a result, no change in brightness could be confirmed.

(Example 2)
A forgery prevention medium was obtained in the same manner as described in Example 1 except that the λ / 8 retardation layer and the λ / 4 retardation layer were separated from each other.

  When this anti-counterfeit medium was observed with the naked eye while irradiating white light, the hue of the colored layer was confirmed in the region corresponding to the colored layer. Further, the area around the colored layer appeared white.

  Next, the counterfeit prevention medium 50 and the verification tool 50 described with reference to FIG. 3 are counterfeited under the same conditions as described above except that the retardation layer 52 faces the anti-counterfeit medium. The image prevention medium was observed. As a result, the region where the λ / 4 retardation layer is formed in the anti-counterfeit medium appears as a bright portion, the region where the λ / 8 retardation layer is formed appears as a dark portion, and the region sandwiched between these regions is a dark portion. Looked as.

  Next, the anti-counterfeit medium was observed under the same conditions as described above except that the anti-counterfeit medium and the verification tool 50 were stacked so that the linearly polarizing film 51 faced the anti-counterfeit medium. When the orientation direction of the mesogen group contained in the λ / 4 retardation layer and the λ / 8 retardation layer of the anti-counterfeit medium and the transmission axis OP of the linearly polarizing film 51 are parallel or orthogonal, the λ / 4 position of the anti-counterfeit medium Reflected light from the region where the phase difference layer was formed, the region where the λ / 8 phase difference layer was formed, and the region sandwiched between them could be observed. However, when the angle formed by the orientation direction of the mesogen group contained in the λ / 4 retardation layer and the λ / 8 retardation layer of the anti-counterfeit medium and the transmission axis OP of the polarizing film 51 is 45 °, λ of the anti-counterfeit medium The region where the / 4 retardation layer was formed changed to a dark part. At this time, the region where the λ / 8 retardation layer was formed was also darker, but brighter than the region where the λ / 4 retardation layer was formed. Further, at this time, the brightness of the region sandwiched between the region where the λ / 4 retardation layer was formed and the region where the λ / 8 retardation layer was formed did not change.

  Next, this anti-counterfeit medium was color copied and verified by the same method as described above using a verification tool. As a result, no change in brightness could be confirmed.

The top view which shows roughly the forgery prevention medium of 1st Embodiment of this invention. Sectional drawing along the II-II line of the forgery prevention medium shown in FIG. The exploded view which shows an example of a verification tool roughly. FIG. 4 is a plan view schematically showing an example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 1 and 2 and the verification tool shown in FIG. 3 are overlapped. The top view which shows schematically the other example of the image which can be observed when the forgery prevention medium shown in FIG. 1 and FIG. 2 and the verification tool shown in FIG. 3 are overlapped. The top view which shows roughly the forgery prevention medium of 2nd Embodiment of this invention. Sectional drawing along the VII-VII line of the forgery prevention medium shown in FIG. The top view which shows schematically the example of the image which can be observed when the forgery prevention medium shown in FIG. 6 and FIG. 7 and the verification tool shown in FIG. 3 are overlapped. FIG. 8 is a plan view schematically showing another example of an image that can be observed when the forgery prevention medium shown in FIGS. 6 and 7 and the verification tool shown in FIG. 3 are overlapped. The top view which shows an example of transfer foil roughly.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Anti-counterfeit medium, 11 ... 1st light reflection area | region, 12 ... 2nd light reflection area | region, 13 ... 3rd light reflection area | region, 21 ... Base material, 22 ... Light reflection layer, 23 ... Orientation film, 24 ... (lambda) / 4 retardation layer, 25 ... colored layer, 26 ... λ / 8 retardation layer, 50 ... verification tool, 51 ... linearly polarizing film, 52 ... λ / 4 retardation layer, 90 ... transfer foil, 91 ... substrate, 92 ... peeling layer, 93 ... adhesive layer.

Claims (12)

  A light reflection layer, a λ / 4 retardation layer facing a part of the front surface of the light reflection layer, and a λ / 8 retardation layer facing a part of the front surface of the light reflection layer. An anti-counterfeit medium characterized by that.   The λ / 4 retardation layer and the λ / 8 retardation layer are adjacent to each other when viewed from the normal direction with respect to the front surface of the light reflecting layer. Anti-counterfeit medium.   The front surface of the light reflecting layer includes first to third light reflecting regions, and the λ / 4 retardation layer faces only the first light reflecting region of the first to third light reflecting regions, and the λ The anti-counterfeit medium according to claim 1, wherein the / 8 retardation layer faces only the second light reflection region among the first to third light reflection regions.   4. A light-transmitting colored layer located in front of the light reflecting layer and facing the λ / 4 retardation layer and / or the λ / 8 retardation layer is further provided. The forgery prevention medium of any one of these.   2. The λ / 4 retardation layer and / or the λ / 8 retardation layer includes a light-transmitting colored layer and a pair of retardation layers sandwiching the colored layer. 4. The forgery prevention medium according to any one of items 1 to 3.   The forgery prevention medium according to claim 1, wherein the light reflection layer includes a reflection layer exhibiting an interference color.   The forgery prevention medium according to claim 1, wherein the light reflection layer includes a diffractive structure.   The λ / 4 retardation layer and / or the λ / 8 retardation layer is a polymer liquid crystal layer, and further includes an alignment film interposed between the polymer liquid crystal layer and the light reflection layer. The forgery prevention medium according to any one of claims 1 to 7.   An anti-counterfeit label comprising the anti-counterfeit medium according to any one of claims 1 to 8, and an adhesive layer supported on a back surface thereof.   A printed matter comprising the anti-counterfeit medium according to any one of claims 1 to 8, and paper into which the anti-counterfeit medium is inserted. An anti-counterfeit medium according to any one of claims 1 to 8,
A base material that releasably supports the front surface of the anti-counterfeit medium,
A transfer foil comprising an adhesive layer supported on the back surface of the anti-counterfeit medium. A method of discriminating between an authentic product and a non-authentic product using a verification tool for an article whose authenticity is unknown.
The genuine product is an article that supports the forgery prevention medium according to any one of claims 1 to 8,
The verification tool includes a linearly polarizing film, and a λ / 4 retardation layer facing one main surface of the linearly polarizing film and having a fast axis of 45 ° with respect to the transmission axis of the linearly polarizing film. And
Visualize the article whose verification is unknown or not and the verification tool by superimposing the λ / 4 retardation layer of the verification tool on the verification tool such that the verification is true or not. If the article that is unknown whether or not it is authentic includes the first and second regions that form a latent image or a visible image with a varying contrast ratio, the article that is authentic or unknown Judging that is a non-genuine product,
The article of which the authenticity is unknown and the verification tool are overlapped with the linearly polarizing film of the verification tool so that the authenticity of the unknown article faces each other, and the verification is performed in this state. The brightness of each of the first region and the second region does not change in accordance with the direction of the transmission axis of the linearly polarizing film when an article of which the authenticity is unknown is observed through a tool. In the case, the determination method includes determining that the authentic or unknown article is a non-authentic item.

Images