JP2009086192A - Forgery prevention structure and forgery prevention sheet using the same, and method for determining authenticity of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forgery prevention structure, which is hardly forged and has a concealed pattern that is hardly recognized with a usual visible light source and can be checked by an extremely simple verification method without using a specified polarization film or a specified verification device or the like, and to provide a forgery prevention sheet using the structure and a method for determining authenticity of the structure. <P>SOLUTION: The forgery prevention structure 1, the forgery prevention sheet and the method for determining authenticity of the sheet are characterized in that: the forgery prevention structure 1 comprises a diffraction structure 2 having a concavo-convex pattern on one surface, a reflection layer 3 provided to cover the concavo-convex pattern, and a polarizer 4 provided on the whole surface in the side opposite to the reflection layer 3; and the diffraction structure 2 has a diffraction grating structure having a periodical cycle of ≤400 nm and an aspect ratio of ≥0.3 or a cross grating structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an anti-counterfeit structure used for a counterfeit-preventing sheet such as a gift certificate, a credit card, or a securities, or a sticker such as a branded product or a high-end product, and a method for determining the authenticity thereof. The present invention relates to an anti-counterfeit structure that enables simple and true determination of authenticity without using a tool or an instrument, an anti-counterfeit structure using the anti-counterfeit structure, and an authenticity determination method thereof.

  In recent years, forgery prevention measures for securities such as gift certificates and credit cards, and anti-counterfeiting measures for proof of authenticity that are often applied to generally expensive items such as branded items and luxury items In general, there are two types of technologies, one of which is an overt technology that can be recognized as a forgery prevention technology by a general user confirming its appearance, and that only a specific user can prevent forgery. It is divided into covert technology that can confirm the anti-counterfeit technology for the first time by knowing the existence of the technology and performing some special verification, and can judge the authenticity.

  Examples of the above-mentioned overt technology include holograms and diffraction gratings that can express stereoscopic images, special decorative images, or special color changes using interference between reflected light and dispersion of the reflected light, and optical A so-called OVD using a technique such as a multilayer thin film that causes a color change (color shift) depending on the viewing angle by superimposing thin films having different characteristics on an optically appropriate multilayer is used. [OVD is an abbreviation for “Optical (ly) Variable Device”. Note that DOVID is also a synonym for OVD, and is an abbreviation for “Differential Optical (ly) Variable Imaging Device”. ].

  This OVD requires advanced manufacturing technology, has a unique visual effect, and can determine authenticity at a glance, so it can be formed on a part or all of credit cards, securities, certificates, etc. as an effective counterfeiting measure. Is being used. Recently, in addition to securities, it is affixed to sports equipment, computer parts and other electrical product software, etc., as an authentication sticker to prove the authenticity of the product, and as a seal sticker to be affixed to the package of those products Has also become widely used. In addition, this OVD is generally a forgery prevention means that is difficult to elaborate and easy to check, but when attached to paper media such as gift certificates, banknotes, passports, stock certificates, etc. The case has been adopted. This is because if the OVD that has been thermally transferred is to be replaced, the optical thin film used in the OVD is physically destroyed, and the original visual effect is impaired. , And an anti-tampering effect.

  On the other hand, examples of the above-mentioned covert technology include fluorescent printing, line latent image, polarization latent image, specific wavelength absorption printing, etc., all of which occupy an important position even today.

  As a typical example of the fluorescent printing, there is fluorescent printing that is printed using a printing ink using a phosphor that is excited by ultraviolet rays and emits visible fluorescence. The phosphors included in these prints are difficult to visually recognize under a normal visible light source, and emit fluorescence in the visible region when irradiated with ultraviolet rays. As the wavelength of the ultraviolet rays to be irradiated, various light sources can be selected depending on the type of phosphor used. In general, a black light that emits ultraviolet light having a wavelength of 365 nm is often used. As a recent technology related to these fluorescent printings, the anti-counterfeiting effect is improved by making the color reproducibility difficult by improving the anti-counterfeiting effect by mixing two or more kinds of phosphors (for example, patents) Reference 1).

  A typical example of the line latent image is line latent image printing by intaglio printing. The line latent image printing is characterized by two or more types of line drawing patterns having a line width of several tens of microns and different patterns depending on the viewing angle and direction. It is also possible to express an arbitrary pattern by copying with a copying machine by adjusting the width and density of the line drawing more finely than the resolution of the copying machine and performing pattern printing. Recent technologies in these line latent images include anti-counterfeiting effects by adding functions by mixing the above-mentioned fluorescent pigments into the ink itself, and by further controlling the copy by performing more precise and fine printing. (For example, refer to Patent Document 2).

  A typical example of the polarized latent image is a liquid crystal display. As for the liquid crystal materials, various advanced polarization technologies have been developed in accordance with the recent increase in demand for liquid crystal displays, and these polarization technologies are beginning to be applied in various forms as anti-counterfeiting devices as covert technologies. For example, there are latent image media using the birefringence of nematic liquid crystal, and latent image bodies using a plastic film having birefringence, and these latent image bodies have desired latent image information when a polarizing element is used. Can be visualized (see, for example, Patent Document 3 and Patent Document 4).

  Furthermore, a representative example of the specific wavelength absorption printing includes printing using an infrared absorbing ink. Infrared absorbing ink used in these printings is composed of pigments and ink binders that absorb in the specific wavelength range of infrared rays (for example, absorbing infrared light having a wavelength of 700 to 1500 nm), and cannot be recognized by humans. This is a pattern, and can be confirmed by using an infrared scope with a visible light cut filter using a CCD camera having sensitivity in the infrared region. Recent technologies related to specific wavelength absorption printing include mixing two or more absorbers having different absorption wavelengths, making it difficult to reproduce the wavelength region, improving the anti-counterfeiting effect, and special and difficult to obtain. The anti-counterfeiting effect is improved by using a specific wavelength absorber (see, for example, Patent Document 5).

The above prior art documents are shown below.
Japanese Patent Laid-Open No. 10-250214 JP 11-291609 A JP 2005-091786 A Japanese translation of PCT publication No. 2002-530687 JP 2004-181791 A

However, in the above-described fluorescent printing technology, the phosphors are generally classified into two types of phosphors that are generally called black light and are excited by ultraviolet rays having a relatively long wavelength of 365 nm and ultraviolet rays having a wavelength of about 254 nm. In the verification, there is an annoyance that a verification device such as a black light is required. In addition, since the above-mentioned line latent image technology does not require a special verification instrument for verification, it can be verified anytime and anywhere, but in recent inkjet printers, it can be improved to control 1 pl droplets. However, there is a problem that the anti-counterfeiting effect is low only by the printing accuracy of the line drawing. In addition, in the above conventional liquid crystal technology, the polarization characteristics are improved and the precision and precision of the pattern are improved. The anti-counterfeiting effect is further improved by the improvement, but the hidden characters and hidden patterns that are expressed cannot be confirmed without using a polarizing film or a polarized light source. Furthermore, the above-described conventional specific wavelength absorption printing technique also has a problem that a verification machine for confirming absorption at a specific wavelength is required.

  The present invention solves such problems of the prior art, and the problem is that it is difficult to counterfeit and difficult to view under a normal visible light source, such as a specific polarizing film, black light, red, etc. An anti-counterfeit structure capable of confirming a hidden pattern that changes in a complex manner by a very simple verification method without using a specific verification device such as an outer scope, an anti-counterfeit structure using the same, and its true It is to provide a false judgment method.

  In order to achieve the above object in the present invention, first, in the invention of claim 1, a diffractive structure having an uneven portion on at least one surface, a reflective layer provided so as to cover the uneven portion, An anti-counterfeit structure comprising a polarizer provided on the entire surface or part of the surface opposite to the reflective layer or the surface of the reflective layer, wherein the diffractive structure has a period of 400 nm or less And an anti-counterfeit structure characterized by having a diffraction grating structure having an aspect ratio of 0.3 or more or a cross grating structure.

  According to a second aspect of the present invention, there is provided a diffractive structure having a concavo-convex portion on at least one surface, a reflective layer provided so as to cover the concavo-convex portion, and a surface opposite to the reflective layer or the reflective layer. A forgery-preventing structure comprising a polarizer provided on the entire surface or a part of the surface, wherein the diffraction structure has a diffraction grating having a period of 400 nm or less and an aspect ratio of 0.3 or more And a forgery-preventing structure characterized by having a cross-grating structure composed of a diffraction grating having a period of 401 nm or more and an aspect ratio of 0.3 or more.

  According to a third aspect of the invention, the polarizer has a pattern having one or more directions, and the pattern is provided on the entire surface or a part thereof. This is a forgery prevention structure described above.

  According to a fourth aspect of the present invention, the diffractive structure has one or more patterns, and the patterns are provided on the entire surface or partially. The anti-counterfeit structure described in 1.

  Moreover, in invention of Claim 5, the forgery prevention sheet | seat body using the forgery prevention structure in any one of Claims 1 thru | or 4.

  The invention according to claim 6 is the method for determining the authenticity of the forgery prevention structure according to any one of claims 1 to 4, wherein the polarizer surface is from the side of the polarizer constituting the forgery prevention structure. The anti-counterfeit structure authenticity determination method is characterized in that the presence or absence of a polarizer is visually confirmed at a shallow angle of 45 ° or less.

  Furthermore, the invention of claim 7 is the method for determining the authenticity of the forgery-preventing single wafer according to claim 5, wherein the anti-counterfeit single-wafer is from the side of the polarizer constituting the anti-counterfeit single-piece body to the polarizer surface. This is a method for determining the authenticity of a forgery-preventing sheet, characterized by visually confirming the presence or absence of a polarizer at a shallow angle of 45 ° or less.

  Since this invention is the above structure, there exist the following effects.

  That is, according to the invention according to the above-described claim, a diffraction structure having an uneven portion on at least one surface, a reflective layer provided so as to cover the uneven portion, and a surface opposite to the reflective layer or An anti-counterfeit structure comprising a polarizer provided entirely or partially on one of the surfaces of the reflective layer, wherein the diffractive structure has a period of 400 nm or less and an aspect ratio of 0.3 or more. A cross having a grating structure or a cross-growing structure, or a diffraction grating having a period of 400 nm or less and an aspect ratio of 0.3 or more, and a diffraction grating having a period of 401 nm or more and an aspect ratio of 0.3 or more By forming the anti-counterfeit structure having a grating structure, the polarizer surface constituting the anti-counterfeit structure has a shallow angle of 45 ° or less with respect to the polarizer surface. Presence of photons, that is, a hidden pattern with complex changes can be visually confirmed, and a prevention structure that can easily determine authenticity without using a troublesome polarizing film or verification machine as in the past It can be set as a body and a forgery prevention sheet body using the same.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of a first forgery prevention structure according to the present invention. The forgery prevention structure (1) includes at least a diffraction structure (2), a reflective layer (3), and a polarizer (4). In this figure, the polarizer (4) is provided in contact with the diffractive structure (2), but a polarizer may be provided on the reflective layer (4) side.

  FIG. 2 is a cross-sectional view of a second forgery prevention structure according to the present invention. This anti-counterfeit structure (1) is a cross comprising at least a diffraction grating having a period of 400 nm or less and an aspect ratio of 0.3 or more, and a diffraction grating having a period of 401 nm or more and an aspect ratio of 0.3 or more. It has a diffractive structure (6) having a grating structure, a reflective layer (7), and a polarizer (8).

  FIG. 3 is a cross-sectional view of a third forgery prevention structure according to the present invention. The anti-counterfeit structure (9) is composed of at least a diffractive structure (10), a reflective layer (11), and a polarizer (12), and the polarizer (12) is a pattern having one or more directions. Pattern A (13) and pattern B (14).

  FIG. 4 is a cross-sectional view of a third forgery prevention structure according to the present invention. The anti-counterfeit structure (15) includes at least a diffractive structure (16), a reflective layer (17), and a polarizer (18), and the diffractive structure (16) has a pattern having one or more directions. Yes, it has pattern C (19) and pattern D (20).

  FIG. 5 is a cross-sectional view of an anti-counterfeit medium as an example of a forgery-preventing single wafer according to the present invention. The forgery prevention medium (32) has a structure in which a forgery prevention structure (34) is laminated on a base material (33).

  FIG. 6 is a cross-sectional view of an anti-counterfeit sticker as another example of the anti-counterfeit sheet according to the present invention. This anti-counterfeit sticker (21) has a structure in which at least a sheet-like support (22), an anti-counterfeit structure (23), and an adhesive (24) are sequentially laminated. These stickers have cutting notches and cuts and become brittle to prevent re-peeling after sticking, making it difficult for improper replacement and improving security.

FIG. 7 is a cross-sectional view of an anti-counterfeit transfer foil as another example of the anti-counterfeit sheet according to the present invention. The anti-counterfeit transfer foil (25) has a structure in which at least a sheet-like support (26) and an anti-counterfeit structure (27) are sequentially laminated, and at least a transfer composed of the anti-counterfeit structure. The layer (28) is peeled off from the support (26) and can be transferred to a transfer target (not shown).

  FIG. 8 illustrates a forgery-preventing sheet as another example of a forgery-preventing sheet according to the present invention. (A) is a front view thereof, and (b) is (a). It is sectional drawing of an AA 'surface. This anti-counterfeit paper (35) is a micro-slit of anti-counterfeit medium (38) composed of an anti-counterfeit structure (36) and a support film (37), and is partially between paper (39) with a window open. It has a structure embedded in.

  FIG. 9 is a schematic diagram of the anti-counterfeit ink used for the anti-counterfeit sheet according to the present invention. This anti-counterfeit ink (29) is obtained by processing the anti-counterfeit structure (30) into a scaly powder and dispersing and mixing it in a binder resin (31).

  FIG. 10 is a schematic diagram for explaining the authenticity determination method for a forgery prevention structure according to the present invention.

  Hereinafter, examples of the anti-counterfeit structure of the present invention and an anti-counterfeit medium using the same will be described in detail including materials used therein.

  The anti-counterfeit structure of the present invention utilizes diffracted light produced by a diffraction grating having a period of not more than visible light (400 nm or less) and its polarization characteristics. For example, in a diffractive structure having a cross grating structure with a period of 300 nm and an aspect ratio of 1, diffracted light from blue to green can be obtained by observation at a shallow angle of 45 ° or less. This diffracted light has TE polarization (s-polarization) characteristics due to the polarization separation effect of the sub-wavelength grating. Vivid blue to green diffracted light having this polarization characteristic cannot be confirmed under a normal light source, but can be confirmed only at a shallow angle of 45 ° or less. By combining the diffracted light having polarization characteristics and a polarizer, a colorful hidden pattern that appears only at a shallow angle of 45 ° or less can be obtained. Similarly, by rotating the anti-counterfeit structure with a shallow angle of 45 ° or less, the pattern of colorful diffracted light is negative-positive inverted.

In general, the polarization separation effect of a diffraction grating (subwavelength grating) having a period of less than or equal to visible light is referred to as TE polarized light (s-polarized light) in a direction that oscillates perpendicularly to the groove of the grating, and TM refers to the direction that oscillates horizontally. This is called polarized light (p-polarized light). When the diffraction grating satisfies the condition of the following formula (A) using the incident angle θ ₀ and the period a with respect to the wavelength λ, the diffraction grating structure is a thin film structure represented by an effective refractive index N _eff for light. It is recognized as progressing inside. At this time, the effective refractive index N _eff varies depending on the incident polarization direction, and is expressed by the following equations (B) and (C) in the first approximation.

a cosθ ₀ <λ ─ (A)
TE polarized light: N _TM = ((1-f) n ₁ ² + fn ₂ ² ) ^1/2 ─ (B)
TM polarization: N _TE = (n ₁ ² fn ₂ ² / fn ₁ ² + (1−f) n ₂ ² ) ^1/2 ─ (C)
Here, n ₁ and n ₂ represent the refractive index of the air layer and the surface of the diffractive structure layer, respectively, and f represents the duty ratio of the yama part of the diffractive structure with respect to the period a. From equations (B) and (C), it can be seen that the effective refractive index for each polarized light is different when f is other than 0 and 1. Under this condition, either effective refractive index N _eff = N _TE or N _eff = N _TM (where N _TE ≠ N _TM ) in each polarization component is a relational expression of refraction of light traveling through different media ( Snell's formula)
N ₁ sinθ ₀ > N _eff ─ (D)
If the above condition is satisfied, incident light having the polarization direction cannot pass through the thin film layer having the effective refractive index N _eff . This state corresponds to a state where the refraction angle θ ₁ in the thin film layer having the effective refractive index N _eff reaches approximately 90 °, and light cannot move to the layer toward the n ₂ side, and the divergence destination of the incident energy As a result, reflected light is generated. As described above, it is known that when the expression (D) is established by the effect of the effective refractive index N _eff in which light in one of the polarization directions is recognized from the lattice structure, the polarizing element with a minute period functions.
[References] Makoto Okada Optics, Vol.35, No.5 (2006) 280-281
[References] Seiichiro Kitagawa et al. O plus E, 26 (2004) 1058-1063
[References] Okada Makoto JETI, June Special Issue (2005) 65-67
[References] Okada Makoto Alliance, 16 (2005) No. 10
The diffractive structure in the present invention applies the above-mentioned “polarization separation effect of a diffraction grating (sub-wavelength grating) having a period of less than visible light”, and at the same time, this polarized diffracted light is only at a specific observation angle. It is characterized by being visible and colorful “visible polarized diffracted light”.

  In addition, by combining a diffractive structure having the above characteristics with another polarizer layer, it is observed only at a shallow angle (or retroreflective direction). An anti-counterfeit structure can be obtained by controlling the area of the colorful polarized diffracted light from the diffractive structure with a polarizer placed thereon.

  Further, the diffraction due to the difference between the light source and the observation position will be described in more detail below.

  FIG. 12 is a schematic side view in the case of the direction of reflection with respect to the diffractive structure surface and when the light source and the observation point are on different sides with respect to the perpendicular to the diffractive structure surface. In this case, the formula (E) is established.

a (sin θ _a −sin θ _b ) = mλ − (E)
FIG. 13 is a schematic side view of the case where the light is reflected from the diffractive structure surface and the light source and the observation point are on the same side with respect to the perpendicular to the diffractive structure surface. In this case, Formula (F) is materialized.

a (sin θ _a + sin θ _c ) = mλ − (F)
In FIG. 12, FIG. 13, and the equations (E) and (F), a is the particle size of the spherical fine particle diffraction structure, θ _a is the incident angle of the light source, θ _b , θ _c , θ _d , θ _e are the rotation times. The folding angle, m is the diffraction order, and λ is the wavelength of the diffracted light.

Here, in the case of a spherical fine particle diffractive structure having a particle diameter a of 400 nm or less according to the present invention, in the formula (E), visible diffracted light (400 to 700 nm) is obtained by any combination of θ _a and θ _b at any angle. I can't confirm. However, in the formula (F), visible diffracted light in any range satisfying 700>λ> 400 in the range of 90 °> θ _a > 60 °, 90 °> θ _c > 0 ° is confirmed. I can do it.

In particular, under the observation conditions as shown in FIG. 12 and formula (E), no visible diffracted light (400 to 700 nm) can be confirmed in any combination of θ _a and θ _b , and FIG. When the diffracted light can be obtained only in the combination of the diffracted light of 30 ° or less and the incident light with respect to the diffractive structure surface under the observation conditions such as), the diffracted light is difficult to understand under a normal visible light source ( Black or dark single color). By setting the incident angle, the diffraction angle, and the wavelength region in this way, it is difficult to understand visible polarized diffracted light under a normal light source. On the other hand, when the observation point is on the same side as the light source as shown in FIG. Visible visible polarized diffracted light can be observed only by a combination of incidence at a shallow angle of 45 ° or less with respect to the plane and a diffraction angle.

The particle size of the spherical fine particle diffractive structure when using such diffracted light in the visible light region is preferably selected from a range of 200 nm to 400 nm according to a desired diffraction wavelength. If the period is less than 200 nm, visible diffracted light cannot be confirmed in either of the above formulas (E) and (F). If the period exceeds 400 nm, the period is equal to or greater than that of visible light. This is because the polarization separation effect is significantly reduced.

  Next, the polarizer which concerns on the forgery prevention structure of this invention is demonstrated. This polarizer can be provided by a known method. For example, there is a kind of polarizing film obtained by stretching a film to which a dichroic dye is added. In addition, an alignment film obtained by applying a rubbing treatment to an alignment film formed by applying polyimide, polyamide and polyvinyl alcohol by spin coating, drying and baking, and then applying and aligning nematic liquid crystal to cure. A polarizer may be obtained by aligning a dichroic dye or a liquid crystal mixed with a dichroic dye by using an alignment film after pattern exposure of a photo-alignment film or a photo-alignment film. It is not limited to. In addition, the polarizer is provided directly on the diffraction grating, or directly forms a diffractive structure on the polarizer, or after the polarizer and the diffractive structure are separately formed, the dry lamination method is performed via an adhesive. Further, they may be bonded together by a known method such as a ruder lamination method or a transfer method.

  Next, the diffraction structure according to the forgery prevention structure of the present invention will be described.

  Next, details of the diffractive structure will be described. As a method for producing a diffractive structure of the present invention, a known method for producing a diffractive structure may be used. For example, a method of molding a thermoplastic resin by hot-pressure embossing, or a photopolymer using a photocurable resin. However, the present invention is not limited to this.

  Next, the reflection layer used for the forgery prevention structure of the present invention will be described. The reflective layer of the present invention is made of an optical thin film provided so as to cover the diffractive structure, and is characterized by reflecting light transmitted through the polarizer. For this reason, an optical effect can also be obtained by using a high refractive index material having a higher refractive index than that of the diffractive structure. In this case, the difference in refractive index between the two layers is preferably 0.2 or more. By setting the difference in refractive index to 0.2 or more, refraction and reflection occur at the interface between the diffractive structure and the reflective layer, and an optical effect due to the structure of the diffractive structure can be obtained. Examples of the material for the reflective layer include simple substances such as Al, Sn, Cr, Ni, Cu, Au, and Ag, or compounds thereof.

Moreover, the example of the high refractive index material which can be used as a transparent reflection layer (4) is given below. The numerical value in parentheses following the chemical formula or compound name shown below indicates the refractive index n. As ceramics, Sb ₂ O ₃ (3.0), Fe ₂ O ₃ (2.7), TiO ₂ (2.6), CdS (2.6), CeO ₂ (2.3), ZnS (2 .3), PbCl ₂ (2.3), CdO (2.2), Sb ₂ O ₃ (5), WO ₃ (5), SiO (5), Si ₂ O ₃ (2.5), In ₂ O ₃ (2.0), PbO (2.6), Ta ₂ O ₃ (2.4), ZnO (2.1), ZrO ₂ (5), MgO (1), Si ₂ O ₂ (10) MgF ₂ (4), CeF ₃ (1), CaF ₂ (1.3 to 1.4), AlF ₃ (1), Al ₂ O ₃ (1), GaO (2), and the like. Examples of the organic polymer include polyethylene (1.51), polypropylene (1.49), polytetrafluoroethylene (1.35), polymethyl methacrylate (1.49), polystyrene (1.60) and the like. These materials are appropriately selected based on optical characteristics such as refractive index, reflectance, and transmittance, weather resistance, interlayer adhesion, and the like, and are formed in the form of a thin film. As a formation method, a known method such as a vacuum evaporation method, a sputtering method, or a CVD method capable of controlling the film thickness, the film formation speed, the number of stacked layers, the optical film thickness, and the like can be appropriately used. Further, by providing a diffraction grating by an oblique deposition method, an oblique sputtering method, or the like, a complicated optical effect in which the direction and angle of diffracted light are controlled can be obtained.

  High glitter ink obtained by dispersing fine particles of these materials in various solvents and fine powders or sols or metal nanoparticles of the above metals, ceramics, or organic polymers in organic polymer resins. Light reflecting ink, organic polymer or organic polymer fine particles can also be used. In this case, care must be taken not to attack the diffractive structure with a solvent, but the diffractive structure can be formed by a known printing method such as a gravure printing method, a flexographic printing method, or a screen printing method. When the reflective layer is provided by such a printing method, the thickness after drying may be adjusted to be about 0.001 to 10 μm.

  The reflective layer (4) made of metal or the like or the transparent reflective layer (4) may be partially provided. In this case, pasta processing, water-washed celite processing, laser processing, and the like can be cited as examples. It is also possible to provide a fine sea-island-like reflective layer by, for example, vacuum deposition of tin or the like.

  The transmittance of the transparent reflection layer (4) is 20% or more in the wavelength region of 400 nm to 700 nm, and information within the reflection layer (4), for example, a face, is within this range. This is because printing information such as photographs, characters, patterns, etc. can be confirmed. Further, in the portion where the transparent reflective layer (4) is disposed, visible information can be provided below the reflective layer, and necessary information and a forgery prevention structure can be laminated. With these technologies, for example, it can be applied to an anti-counterfeit oversheet that can be used in an ID card, a passport, or the like.

  As one example of the anti-counterfeit sheet according to the present invention, for example, in the anti-counterfeit sticker (21) as shown in FIG. 6, the support (22) and the adhesive (24) are used, for example, for manufacturing a known sticker. Can be produced using appropriate materials and techniques. In addition, it is possible to provide a part to be peeled between layers or to make a notch in the sticker so that the sticker will be destroyed if it is illegally peeled off. According to this, since the sticker is destroyed, it is effective in preventing reuse even if an attempt is made to replace the sticker with another base material and try to use it. This also destroys the sticker, so if you have read the secret information (if there is secret information underneath the sticker) It is also effective in preventing fraud such as pasting this genuine sticker on the original part after falsifying the information.

  Moreover, as one example of the forgery-preventing sheet material of the present invention, for example, the support (26) in the forgery-preventing transfer foil (25) as shown in FIG. 6 has a stable thickness and high heat resistance. A polyethylene terephthalate resin film is generally used, but the material is not particularly limited. As other film materials, a polyethylene naphthalate resin film, a polyimide resin film, or the like exhibiting high heat resistance can be used for the same purpose. Also, when performing follow-up transfer to a three-dimensional shape under heating conditions, such as vacuum transfer, use film materials that soften by heating, such as polyethylene, polypropylene, vinyl chloride, A-PET, etc. I can do it.

In the forgery prevention transfer foil (25), the forgery prevention structure (27) may be peelable from the support (26). A layer called a release protective layer (not shown) that can be peeled off from the support or a release layer that is not peeled off from the support is provided between the support (26) and the forgery prevention structure (27). However, none of these layers are required. That is, these layers are appropriately provided by design for the purpose of protecting the surface of the transferred anti-counterfeit structure (27) or for the purpose of improving the transfer performance at the time of transfer by obtaining a stable peel strength. Is also a good option. Examples of the peeling protection layer (not shown) include polymethyl methacrylate resin and other thermoplastic resins such as a mixture of vinyl chloride / vinyl acetate copolymer or nitrocellulose resin, or a mixture of polymethyl methacrylate resin and polyethylene wax. It is done. A preferable example is one obtained by applying a mixture of a cellulose acetate resin and a thermosetting resin such as an epoxy resin, a phenol resin, a thermosetting acrylic resin, or a melamine resin, and then curing it by heat. Examples of the release layer include resins having a release property such as a silicon resin and a fluorine resin, and a release paper material is particularly used. By applying these resins to the support (26), it is possible to control the release property and peelability of the laminate.

  Moreover, in the said forgery prevention transfer foil (25), an adhesive bond layer is not necessarily essential. The adhesive for adhering at the time of transfer may be provided on the outermost layer on the side different from the support relative to the anti-counterfeit structure (27) of the transfer foil, or may be provided on the outermost layer of the non-transferred material. The adhesive layer can be formed in an arbitrary pattern. In general, as an adhesive, a known heat-sensitive resin (heat-sensitive adhesive having a function of adhering to a transfer material by being applied with heat and pressure in contact with various transfer materials (for example, paper and plastic). Material) is used.

  In the anti-counterfeit ink (29) used for the anti-counterfeit sheet according to the present invention, for example, as shown in FIG. 7, the anti-counterfeit structure (30) is processed into a scaly powder. When used as a pigment for printing ink, the particle size may be adjusted by the printing method, coating amount, etc., and a known printing binder or vehicle can be used as the binder resin (31).

  For example, in the anti-counterfeit medium (32) as shown in FIG. 5, as the base material (33), for example, banknotes, polymer banknotes, securities such as gift certificates and credit cards, brand goods, luxury goods, etc. In general, expensive ones, packages and the like are not limited thereto. In order to laminate the base material (33), an anti-counterfeit structure (34) can be provided via an adhesive (not shown). Alternatively, a forgery prevention sticker (21) as shown in FIG. 6 and a forgery prevention transfer foil (25) as shown in FIG. Furthermore, forgery prevention ink (29) as shown in FIG. 8 can be applied to the base material (33).

  In the anti-counterfeit paper (35) as an example of the anti-counterfeit sheet according to the present invention, the support film (37) shown in FIG. 8 (b) has a stable thickness and a high heat resistance polyethylene. In addition to terephthalate resin film, polyethylene naphthalate resin film, polyimide resin film, etc., polyethylene, polypropylene, vinyl chloride, etc. can be used, but it is limited to this as long as it meets the required quality of paper, dimensional stability, etc. Not. Further, the anti-counterfeit paper (35) does not necessarily require the support film (37). Usually, in the case of squeezing into paper, a forgery prevention structure (36), a forgery prevention sticker (21) shown in FIG. 6, a forgery prevention transfer foil (25) shown in FIG. 7, or a forgery prevention medium ( Any one or more of 32) may be formed into an arbitrary shape and then inserted into paper (39). For example, an elongate slit-shaped object can be seen as a continuous straight line, or fine powder can be seen as an example.

  In the above, detailed explanation of each member has been made based on the examples, but each layer is colored to improve the design, printing on the surface or between layers, or the step of any layer installed in a pattern It can be used appropriately depending on the purpose of use, such as applying an overcoat that makes the film inconspicuous. Moreover, in view of the adhesiveness of each layer, it is possible to provide an adhesion anchor layer between each layer, and to perform various easy adhesion treatments such as corona discharge treatment, plasma treatment, and flame treatment. Further, for the purpose of removing light other than the diffracted light of the diffractive structure, a black layer (light absorption layer) or a colored layer (specific wavelength absorption layer) is entirely provided under the anti-counterfeit structure (1), or It is possible to provide an arbitrary pattern, or to additionally provide a reflection layer or a scattering layer for reflecting and scattering light other than the diffracted light of the diffractive structure in the regular reflection direction.

Next, the authenticity determination method of the present invention will be described. As this true / false determination method, for example, as shown in FIG. 10, the anti-counterfeit structure (1) may be checked for the presence of the polarizer (6) at an angle of 45 ° or less with respect to the anti-counterfeit structure. . Although not specifically illustrated, for example, it is possible to apply parallel light from a polarized light source from an angle of 45 ° or less with respect to the plane of the anti-counterfeit structure and confirm the diffracted light of the hidden pattern from the retroreflection direction. . In this case, verification can be performed even from a certain distance.

  Specific examples of the present invention will be described below.

<Example 1>
Acrylic resin is printed on a 25 μm PET film by a bar coat printing method with a dry film thickness of 1.0 μm, dried in an oven at 120 ° C. for 3 minutes, and then diffracted with a period of 300 nm and an aspect ratio of 1 by a heat embossing method. Created a structure. Thereafter, 800 mm of aluminum was deposited on the diffractive structure by vacuum deposition to provide a reflective layer. The obtained diffractive structure with a reflective layer usually exhibits a deep reddish purple color under a light source, but emits diffracted light from blue to green only at a shallow angle of 45 ° or less, and more than 80% of this diffracted light is emitted. It was confirmed to be TE polarized light (s polarized light).

  After applying polyimide to the diffractive structure side of the obtained diffractive structure with a reflective layer and drying, rubbing it in a pattern with rayon to obtain an alignment film, and then applying and curing nematic liquid crystal to form a patterned polarizer The forgery prevention structure was obtained.

  The obtained anti-counterfeit structure is difficult to understand under a normal light source, and by using an observation angle of 45 ° or less without using a verification machine, it is possible to confirm a hidden pattern with vivid colors, and The hidden pattern was negative-positive inverted by rotating the anti-counterfeit structure while maintaining the observation angle.

<Example 2>
An acrylic resin is printed on a 25 μm PET film by a bar coat printing method with a dry film thickness of 1.0 μm, dried in an oven at 120 ° C. for 3 minutes, and then a thermal embossing method with a period of 300 nm and an aspect ratio of 1 A diffractive structure was created. Thereafter, 800 mm of aluminum was deposited on the diffractive structure by a vacuum deposition method to provide a reflective layer. The obtained diffractive structure with a reflective layer usually exhibits deep reddish purple under a light source, but emits blue to green diffracted light only at a shallow angle of 30 ° or less, and more than 80% of this diffracted light is emitted. It was confirmed to be TE polarized light (s polarized light).

  A forgery prevention structure was obtained by attaching a polarizing film in a pattern with an acrylic pressure-sensitive adhesive to the reflection layer side of the obtained diffraction structure with a reflection layer.

  The obtained anti-counterfeit structure is difficult to understand under a normal light source, and by using an observation angle of 45 ° or less without using a verification machine, it is possible to confirm a hidden pattern with vivid colors, and The hidden pattern was negative-positive inverted by rotating the anti-counterfeit structure while maintaining the observation angle.

<Example 3>
An acrylic resin is printed on a 25 μm PET film by a bar coat printing method with a dry film thickness of 1.0 μm, dried in an oven at 120 ° C. for 3 minutes, and then stamped by a hot embossing method so that the period ratio is 300 nm. Each pattern of the diffractive structure part and the diffractive structure part having a period of 500 nm aspect ratio of 1 was prepared simultaneously. Thereafter, 800 mm of aluminum was deposited on the diffractive structure by vacuum deposition to obtain a reflective layer.

In the diffractive structure with a reflection layer of the obtained diffractive structure having a period of 500 nm and an aspect ratio of 1, the color is usually green by visual observation under a light source, and gradually changes from green to red by changing the observation angle. It was confirmed that vivid diffracted light that changes color can be obtained.

  On the other hand, the diffractive structure with a period of 300 nm aspect ratio of 1 exhibits a deep reddish purple color under normal light source and does not change color, but emits bright blue to green diffracted light only at a shallow angle of 30 ° or less. It was confirmed that 80% or more of the diffracted light was TE polarized light (s-polarized light). A forgery prevention structure was obtained by attaching a polarizing film in a pattern with an acrylic pressure-sensitive adhesive to the reflection layer side of the obtained diffraction structure with a reflection layer.

  In this anti-counterfeit structure, under a normal light source, a vivid color change is confirmed by diffracted light from a diffractive structure portion with a period of 500 nm aspect ratio 1, while a diffractive structure portion with a period of 300 nm aspect ratio 1 is under a normal light source. Visible green polarized diffracted light is emitted visually only at a shallow observation angle of 30 ° or less, and a hidden pattern by a polarizing film can be confirmed by visual observation without using a verification film such as a polarizer. done. In addition, the negative / positive reversal of the hidden pattern by the polarizing film was confirmed by rotating the forgery prevention structure while maintaining the observation angle.

  Below, the comparative example of this invention is demonstrated.

<Comparative Example 1>
A forgery prevention structure was produced in the same manner as in Example 1 except that the aspect ratio of the diffractive structure was 0.2. The contrast of the hidden pattern of the obtained forgery prevention structure was low, and visual recognition was difficult.

<Comparative example 2>
A forgery prevention structure was prepared in the same manner as in Example 1 except that the period of the diffraction structure was 500 nm. It was difficult to visually recognize the hidden pattern of the obtained forgery prevention structure.

It is explanatory drawing which represented one Embodiment of the forgery prevention structure of this invention in the cross section. It is explanatory drawing which represented other embodiment of the forgery prevention structure of this invention in the cross section. It is explanatory drawing which represented other embodiment of the forgery prevention structure of this invention in the cross section. It is explanatory drawing which represented other embodiment of the forgery prevention structure of this invention in the cross section. It is explanatory drawing which represented one Embodiment of the forgery prevention sheet body of this invention with the cross section. It is explanatory drawing which represented in cross section other embodiment of the forgery prevention sheet body of this invention. It is explanatory drawing which represented in cross section other embodiment of the forgery prevention sheet body of this invention. The other embodiment of the forgery prevention sheet material of this invention is demonstrated, (a) is the front view, (b) represented the AA 'surface of (a) with the cross section. It is explanatory drawing. It is a schematic diagram of the forgery prevention ink used for the forgery prevention sheet body of this invention. It is a conceptual diagram explaining the authenticity determination method of the forgery prevention structure of this invention. It is a conceptual diagram of the diffraction by the diffraction grating which comprises one example of the forgery prevention structure of this invention. It is a side surface schematic diagram explaining the example of the observation position of the forgery prevention structure of the present invention. It is a side surface schematic diagram explaining the other example of the observation position of the forgery prevention structure of this invention.

Explanation of symbols

1, 5 ... Anti-counterfeit structure 2, 6 ... Diffraction structure 3, 7 ... Reflective layer 4, 8 ... Polarizer 21 ... Anti-counterfeit sticker 22 ... Sheet-like support 23 ... Anti-counterfeit Structure 24 ··· Adhesive 25 · · · Anti-counterfeit transfer foil 26 · · · Sheet-like support 27 · · · Anti-counterfeit structure 28 · · · Transfer layer 29 · · · Anti-counterfeit ink 30 · · · Anti-counterfeit structure 31 ··· Binder resin 32 ... Anti-counterfeit medium 33 ... Base material 34 ... Anti-counterfeit structure 35 ... Anti-counterfeit paper 36 ... Anti-counterfeit structure 37 ... Support film 38 ... Anti-counterfeit medium 39 ... Paper 50 ... ··· Plane on which anti-counterfeit structure is formed 55 · · · Observation point at an angle of 45 ° or less with respect to the anti-counterfeit structure

Claims (6)

  A diffractive structure having a concavo-convex portion on at least one surface, a reflective layer provided so as to cover the concavo-convex portion, and a whole surface or a part of either the surface opposite to the reflective layer or the surface of the reflective layer The anti-counterfeiting structure is composed of a polarizer that is provided, and the diffraction structure has a diffraction grating structure having a period of 400 nm or less and an aspect ratio of 0.3 or more, or a cross grating structure. An anti-counterfeit structure characterized by that.   A diffractive structure having a concavo-convex portion on at least one surface, a reflective layer provided so as to cover the concavo-convex portion, and a whole surface or a part of either the surface opposite to the reflective layer or the surface of the reflective layer The anti-counterfeiting structure is composed of a polarizer provided, and the diffraction structure includes a diffraction grating having a period of 400 nm or less and an aspect ratio of 0.3 or more, a period of 401 nm or more, and an O.D. An anti-counterfeit structure having a cross grating structure comprising a diffraction grating having an aspect ratio of 3 or more.   The anti-counterfeit structure according to claim 1, wherein the polarizer has a pattern having one or more directions, and the pattern is provided on the entire surface or a part thereof.   The anti-counterfeit structure according to claim 1 or 2, wherein the diffractive structure has one or more patterns, and the patterns are provided on the entire surface or partially.   A forgery-preventing single wafer using the anti-counterfeit structure according to any one of claims 1 to 4.   The anti-counterfeit structure according to any one of claims 1 to 4 and the authenticity determination method for anti-counterfeit sheet according to claim 5, wherein the anti-counterfeit structure or anti-counterfeit sheet is configured. A forgery-preventing structure and a forgery-preventing single-wafer authenticity determination method, wherein the presence or absence of a polarizer is visually confirmed from a polarizer surface side at a shallow angle of 45 ° or less with respect to the polarizer surface.

Images