JP2009134093A - Diffraction structure, forgery prevention medium using the same, and forgery prevention paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a unique diffraction structure capable of further improving the effect for preventing forgery and allowing a user to determine whether the card and the paper are genuine or forgery simply at a glance; a forgery prevention medium for card or the like using the same; and a forgery prevention paper such as security paper or the like. <P>SOLUTION: The diffraction structure 20 is constituted by laminating a plurality of diffraction structure forming layers having different diffraction structures on one surface of a transparent base 1 and laminating four layers including the first diffraction structure forming layer 2 provided with an embossed face 3 being at least the diffraction structure, a light reflecting layer 3, the second diffraction structure forming layer 5 provided with an embossed face 6 being the diffraction structure being different from the first diffraction structure forming layer 2, and a light reflecting layer 7 in this order. The diffraction structure 20 is constituted by the diffraction structures being diffraction grating for diffracting only optional specific wavelength. The forgery prevention medium and the forgery prevention paper use this diffraction structure 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a diffractive structure having an anti-counterfeit function for making counterfeiting and tampering difficult, an anti-counterfeit medium using the same, and an anti-counterfeit paper.

  Conventionally, the means for preventing counterfeiting is to make it difficult to imitate the article itself, or to attach authenticity to the article as an authentic proof so that authenticity can be determined. There is something. For example, the former uses fine printing and watermark processing on itself, such as securities such as banknotes and stock certificates, uses colors that are difficult to reproduce, and makes the material itself special. Forgery by printing technology and forgery by copying machines and scanners are difficult.

  However, with the advancement of digital technology, it has become possible to easily reproduce even fine printing processes and colors that have been difficult to counterfeit as described above with color copies and scanners. As a result, the printing process as an anti-counterfeiting measure has been further refined, making duplication and forgery more difficult, but as the miniaturization progresses in this way, it is not possible to make a true / false judgment at a glance. Therefore, it is not easy to determine their authenticity.

  Therefore, it is possible to easily determine the authenticity at a glance by attaching it to an article (anti-counterfeit object), and since it is easy to handle, a diffraction structure in which a diffraction grating pattern is recorded is widely used as a forgery prevention means. It was to be used. Examples of the diffractive structure employed as such anti-counterfeiting means include a peelable layer having a releasability on a substrate, a diffractive structure forming layer having a diffraction grating formed thereon, a reflective layer having a metallic luster, and an adhesive layer. There is a structure in which a diffraction structure is formed into a transfer foil by laminating sequentially (see, for example, Patent Document 1).

  In addition, there is a structure in which a diffractive structure forming layer is directly provided on a base material, and a reflective layer and an adhesive processing layer are sequentially laminated to form a sticker (for example, see Patent Document 2).

  There are many manufacturing methods for forming the diffraction grating pattern of the diffraction structure, and the present invention is not limited to this manufacturing method. As an example, a manufacturing method of the relief type diffraction structure will be described.

  The relief type diffractive structure is a diffraction grating pattern in which arbitrary image information is recorded as interference fringes formed on a diffractive structure forming layer in an uneven shape. However, this unevenness causes interference to reproduce arbitrary image information at a certain angle with respect to incident light or an angle within a certain range. This relief type diffractive structure is used in many diffractive structures at present because it can be produced in large quantities by producing an original plate on which image information is recorded with unevenness and embossing it.

  In addition, some transparent diffraction gratings that are positioned below the reflective layer by forming a transparent metal vapor-deposited thin film or an inorganic compound thin film on the reflective layer can be visually observed through the diffraction grating. (For example, refer to Patent Document 3).

  Further, a plurality of diffractive structure forming layers are provided so that the same pattern or different patterns can be reproduced in different reproduction directions, and a plurality of patterns can be superimposed and reproduced (see, for example, Patent Document 4). ).

  However, these conventionally used diffractive structures all generate diffracted light when light enters the diffractive structure forming layer formed on one side of the diffractive structure, and the diffracted light is reflected by the reflective layer. By transmitting through the layer, the diffracted light is observed from the light incident side, and even if light is applied to the opposite surface, it is shielded by an opaque base material, or the base material is transparent. However, since the reflective layer is positioned in front of the diffractive structure forming layer, diffracted light cannot be observed, and as a result, diffracted light can be observed only from one side of the diffractive structure.

The above prior art documents are shown below.
JP-A-61-190369 Japanese Patent Publication No. 1-54709 Japanese Patent Laid-Open No. 11-91297 JP-A-7-199781

  However, even for a diffractive structure as a forgery prevention measure as described above, it is possible to easily determine authenticity at a glance due to advances in simplification and cost reduction of the manufacturing method of the diffractive structure. There is an increasing number of counterfeiting of diffractive structures, and recently, there is a problem that its anti-counterfeiting effect is fading.

  In addition, special light emission (or absorption) ink that uses authenticity of UV or IV to determine authenticity is also used as a measure to prevent counterfeiting of securities and banknotes. There is a problem that it is necessary and authentication cannot be judged at a glance.

  The present invention solves the problems of the prior art, and the problem is that the anti-counterfeiting effect is further improved, and the true / false judgment can be easily performed at a glance, and both the front and back sides of the base material are provided. Another object of the present invention is to provide a unique diffractive structure capable of observing diffracted light, a card forgery prevention medium such as a card, and a counterfeit prevention paper such as a security paper.

  In order to achieve the above object in the present invention, first, in the invention of claim 1, a plurality of diffractive structure forming layers in which different diffractive structures are formed are laminated on the entire surface or a part of one side of the transparent substrate. A second diffractive structure different from the first diffractive structure forming layer, the light reflecting layer, and the second diffractive structure formed at least. The diffraction structure forming layer and the light reflecting layer are laminated in order.

  According to a second aspect of the present invention, the transparent base material is a diffractive structure according to the first aspect, wherein a plurality of layers having different refractive indexes are laminated.

  The invention according to claim 3 is the diffraction structure according to claim 1 or 2, wherein a colored image pattern is printed on at least one surface of the transparent substrate.

According to a fourth aspect of the present invention, the diffractive structure is a diffractive grating that diffracts only an arbitrary specific wavelength. The diffractive structure according to any one of the first to third aspects is provided. .

  According to a fifth aspect of the present invention, the light reflecting layer is partially patterned and laminated on the diffractive structure forming layer. The diffraction according to any one of the first to fourth aspects It is a structure.

  In the invention of claim 6, a transparent protective layer for protecting the light reflecting layer on the light reflecting layer exposed on the outermost surface of the light reflecting layer and / or the base material, the diffraction structure forming layer, the light 6. The diffractive structure according to claim 1, wherein a close adhesion auxiliary layer for improving the adhesion of each layer is provided between the respective layers of the reflective layer.

  According to a seventh aspect of the present invention, there is provided a forgery prevention medium using the diffractive structure according to any one of the first to sixth aspects, wherein there is no diffractive structure forming layer of the transparent substrate constituting the diffractive structure. This is a forgery prevention medium characterized in that a pattern, characters and / or an information recording medium are provided on the surface.

  The invention according to claim 8 is an anti-counterfeit medium using the diffraction structure according to any one of claims 1 to 6, wherein there is no diffraction structure forming layer of the transparent substrate constituting the diffraction structure. The medium is a forgery prevention medium characterized in that the surface is applied to a transparent article that requires prevention of forgery.

  Furthermore, in the invention of claim 9, forgery prevention paper using the diffractive structure according to any one of claims 1 to 6, which is forged or pasted on paper. It is a prevention paper.

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

  That is, according to the first aspect of the present invention, in the diffractive structure in which a plurality of diffractive structure forming layers in which different diffractive structures are formed are laminated on the entire surface or a part of one surface of the transparent substrate. A first diffractive structure forming layer on which at least the diffractive structure is formed, a light reflecting layer, a second diffractive structure forming layer on which a diffractive structure different from the first diffractive structure forming layer is formed, and a light reflecting By layering the four layers in order, an unprecedented visual effect is obtained in which an observer can observe the diffracted light regardless of whether the light is incident from the front surface or the back surface of the diffractive structure. The diffraction structure can be made.

  According to the second aspect of the present invention, since the transparent base material is composed of a plurality of layers having different refractive indexes instead of a single layer, the color of the base material itself varies depending on the observation angle. Therefore, a diffractive structure with a further enhanced visual effect can be obtained.

  Further, according to the third aspect of the present invention, the diffracted light when observed from the substrate side is printed by printing an image pattern such as colored characters and designs on one side of the substrate. It is possible to observe by coloring the color and to improve the design.

  According to the invention of any one of claims 1 to 3, it is preferable that at least one of the light reflecting layers is formed of a metal thin film having a light transmittance of 1 nm to 1000 nm. The diffracted light from the diffractive structure of the multiple diffractive structure forming layers can be observed not only from the observation surface side, but also from the opposite side of the observation surface, obtaining an unprecedented visual effect and further counterfeiting The prevention effect can be enhanced.

  According to the fourth aspect of the present invention, the diffraction structure is a diffraction grating (pattern) that diffracts only an arbitrary specific wavelength, so that light is incident on the diffraction grating pattern and an image is obtained. The wavelength of the diffracted light that is the reproduction light when reproducing the light is limited, and the diffractive structure forming layer in the diffractive structure can diffract only any specific wavelength.

  According to the fifth aspect of the present invention, the light reflecting layer is not formed on the entire surface of the diffractive structure layer, but is partially formed in a pattern such as a character or a picture. It is possible to increase the anti-counterfeiting effect.

  Moreover, according to the 6th invention which concerns on the said Claim 6, in the diffraction structure in any one of Claims 1-5, between a base material and a light reflection layer, or between a diffraction structure layer and a protective layer. By providing an adhesion auxiliary layer for enhancing adhesion and providing a protective layer for protecting the light reflecting layer exposed on the outermost surface, it is possible to obtain a diffraction structure with further improved durability. .

  Further, according to the seventh invention according to the seventh aspect, on the back surface of the base material constituting the diffractive structure according to any one of the first to sixth aspects, printing of a pattern and characters, and / or a magnetic tape By attaching or embedding an information medium such as an IC chip or the like, the forgery prevention effect can be further enhanced, and a forgery prevention medium such as a membership card, magnetic card, or IC card that is extremely difficult to forge or tamper with can be obtained.

  According to the eighth aspect of the present invention, the back surface of the transparent substrate constituting the diffractive structure according to any one of claims 1 to 6 is applied to a transparent article that requires anti-counterfeiting. Thus, the anti-counterfeit effect can be further enhanced, and a forgery-preventing medium made of a transparent article such as a branded product that requires anti-counterfeiting that is very difficult to counterfeit or falsify.

  Still further, according to the ninth aspect of the present invention, forgery prevention is performed by placing the diffractive structure according to any one of claims 1 to 6 on paper so that both surfaces thereof are partially exposed. Anti-counterfeit paper that is more effective and can be used for tickets and gift certificates that are more difficult to counterfeit or falsify by allowing diffracted light to be observed from either side of the paper. Can be paper.

  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 showing an example of the diffractive structure 20 of the first invention, and a diffractive structure forming layer 2 that generates diffracted light by light incident from the back side on a base material 1 through which light can pass. It has an embossed surface 3 that is a diffractive structure, and a light reflecting layer 4 that reflects diffracted light.

  A diffractive structure forming layer 5 that generates diffracted light by light incident from the surface, an embossed surface 6 that is a diffractive structure, and a light reflective layer 7 that reflects diffracted light are laminated on the light reflecting layer 4. Further, a protective structure 8 for protecting the surface from scratches caused by friction and adhesion of various chemicals is laminated on the light reflecting layer 7, which is a diffractive structure 20 having a basic layer structure of the present invention.

FIG. 2 is a diagram showing that diffracted light is generated on the front and back sides of the diffractive structure 20 of the first invention shown in FIG. 1. The diffracted light b is shown on the front surface and the diffracted light d is shown on the back surface. It shows that it is generated. First, on the surface, when the incident light a reaches the embossed surface 6 which is a diffraction structure in which the light reflecting layer 7 is formed through the protective layer 8, the light reflected along the embossed surface 6 is diffracted. Depending on the phenomenon, it becomes diffracted light b and proceeds in the direction shown in the figure, and the diffracted light can be observed on the surface. On the other hand, on the back surface, the incident light c is transmitted through the light-transmitting substrate 1 and the diffractive structure forming layer 2 and is diffracted on the embossed surface 3 which is a diffractive structure formed on the upper end surface of the diffractive structure forming layer 2 d is generated, and the diffracted light d is reflected by the light reflecting layer 4 and again passes through the base material 1 and proceeds in the direction shown in the figure, so that the diffracted light can be observed on the back surface. As a result, the diffractive structure 20 in which diffracted light can be observed on both the front and back sides can be obtained.

  3 shows a diffractive structure in which an image pattern 12 is provided on a surface of the base material 1 of the diffractive structure 20 shown in FIG. FIG. 20 is a cross-sectional view of the diffractive structure 20 according to the third aspect of the present invention.

  4 is a cross-sectional view of an anti-counterfeit medium 30 in which a printed layer 9 is provided on a back surface of the base material 1 of the diffraction structure 20 shown in FIG. It is an example which shows the basic layer structure of 7th invention.

  FIG. 5 is a cross-sectional view of the anti-counterfeit medium 30 manufactured by attaching the magnetic tape 10 to the back surface of the substrate 1 of the diffractive structure shown in FIG. 1 and cutting it to an arbitrary (card) size. There is another example of the forgery prevention body 30 of the seventh invention.

  FIG. 6 is manufactured by enclosing a non-contact IC inlet 15 including an IC chip 13 and an antenna 14 in the base material 1 constituting the diffractive structure 20 shown in FIG. 1 and cutting it to an arbitrary (card) size. FIG. 6 is a cross-sectional view of the forgery prevention medium 30 and is another example of the forgery prevention body 30 of the seventh invention.

  FIG. 7 is a plan view of the anti-counterfeit paper 40 using the diffractive structure of the first invention. The diffractive structure 20 shown in FIG. 1 is cut into a thread shape, and the thread-like diffractive structure. This is an example of the forgery-preventing paper 40 according to the ninth aspect of the invention in which the front and back surfaces of 20a are partially exposed from the paper 11.

  8 is a cross-sectional view of the exposed portion AA of the thread-like diffractive structure 20a of FIG. 7, and FIG. 9 is a cross-sectional view of the paper making portion along BB. The thread-like diffractive structure 20a can observe diffracted light on both the front and back sides. Therefore, even when the thread-like diffractive structure 20a is made on paper, Although it is completely buried in the paper, both the front and back sides are exposed at the exposed part.

  FIG. 10 is a plan view showing another example of the anti-counterfeit paper 40 of the present invention. The thread-like diffractive structure 20a obtained by cutting the diffractive structure into a thread shape is exposed from the paper 11 alternately on the front and back sides. FIG. 11 is a cross-sectional view of the portion AA where the thread-like diffractive structure 20a is exposed on the front surface in FIG. 10, and FIG. 12 is a thread-like shape on the back surface. It is sectional drawing of the part BB where the diffraction structure 20a is exposed.

  Below, the diffraction structure of the present invention and the material and forming method of each layer constituting the anti-counterfeit medium using the same will be explained.

〔Base material〕
First, a resin film can be used as the transparent substrate 1, and examples of the resin film include polyethylene terephthalate resin film, polyethylene naphthalate resin film, polyimide resin film, polyethylene resin film, polypropylene resin film, and heat-resistant vinyl chloride film. It is done. Among these resins, a polyethylene terephthalate resin film is preferably used because of its high heat resistance and stable thickness. A single layer of these resin films may be used, but a plurality of films having different refractive indexes may be laminated, and a color change is developed in the substrate 1 itself depending on an observation angle, and further visual effects are obtained. An enhanced diffractive structure 20 can be obtained.

  Moreover, the film which processed antistatic treatment, mat processing, embossing, printing of a character and a pattern, laser marking etc. can also be used for these resin films.

(Diffraction structure)
A diffractive structure such as a relief-type diffraction grating or a volume-type diffraction grating can be used for the embossed surfaces 3 and 6 having a diffractive structure formed on the diffractive structure forming layers 2 and 5.

  The relief type diffraction grating has a diffraction grating recorded in the form of a fine concavo-convex pattern on the surface as embossed surfaces 3 and 6 which are diffractive structures. Such a concavo-convex pattern is obtained by, for example, irradiating the surface of the photosensitive resin with two coherent light beams using the two-beam interference method to generate an interference pattern on the surface of the photosensitive resin. Can be formed by recording in a photosensitive resin in the form of irregularities. The interference fringes formed by the two-beam interferometry are also diffraction gratings, and an arbitrary three-dimensional image can be recorded as a diffraction grating pattern by selecting the two light beams. It is also possible to record so that different images (hereinafter referred to as changing images) can be seen depending on the viewing angle.

  Regarding the method of recording an image pattern to be a diffractive structure used in the present invention, in addition to the two-beam interference method, conventionally known holograms such as an image hologram, a Lippmann hologram, a rainbow hologram, and an integral hologram are used. It can be manufactured by a manufacturing method.

  Further, the concavo-convex pattern of the relief type diffraction grating can form a diffraction structure by irradiating the surface of the electron beam curable resin with an electron beam and exposing it to a striped pattern to be a diffraction grating. In this case, since the interference fringes can be controlled for each line, any three-dimensional image or changing image can be recorded in the same manner as the hologram. It is also possible to divide the image into dot-like pixel areas, record different diffraction gratings for each pixel area, and express the entire image with a set of these ancestors. The pixel may be a circular dot or a star dot.

It is also possible to form the concavo-convex pattern by an induced surface relief forming method. That is, by irradiating a polymer amorphous thin film having azobenzene on the chain side with a relatively weak light of about several tens of mW / cm ² having a certain wavelength ranging from blue to green, several μm scale As a result, movement of polymer molecules can be caused, and as a result, relief by unevenness can be formed on the surface of the thin film.

  Then, by forming a metal film on the surface of the relief-type master plate having the uneven pattern formed in this way by electroplating, the uneven pattern of the relief-type master plate is duplicated and used as a press plate. And this press plate is thermocompression-bonded to the resin layer coated on the substrate 1 and the resin layer on which the light reflecting layer 7 is formed, and a fine uneven pattern is transferred to the surface of the resin layer. The diffractive structure forming layer 2 on which the embossed surface 3 of the diffractive structure is formed can be obtained.

  As the resin applied to the diffractive structure forming layers 2 and 5 by the relief type diffraction grating, thermoplastic resins, thermosetting resins, ultraviolet rays, electron beam curable resins, or the like can be used. For example, acrylic resins include acrylic resins, epoxy resins, cellulose resins, vinyl resins, and the like. In addition, urethane resins, melamine resins, phenol resins, and the like obtained by adding polyisocyanate as a crosslinking agent to an acrylic polyol or polyester polyol having a reactive hydroxyl group and crosslinking can be used. Further, as the ultraviolet ray or electron beam curable resin, epoxy (meth) acryl, urethane (meth) acrylate, or the like can be used.

  Further, as the diffractive structure forming layers 2 and 5, an optical multilayer interference film that is a multilayer thin film, a layer of cholesteric liquid crystal, an ink containing powder that can see different colors depending on an observation angle, and the like can be used.

  The optical multilayer interference film may be a metal thin film, a ceramic thin film, or a composite thin film formed by combining them with an appropriate number of layers stacked depending on the relationship between the optical characteristics of each layer and the layer combination. For example, when thin films having different refractive indexes are stacked, a high refractive index thin film and a low refractive index thin film may be combined, or a specific combination may be stacked alternately. An optical multilayer interference thin film that exhibits a desired optical effect (here, a structural color) can be obtained by an appropriate combination that satisfies the optical conditions of these layers.

  Examples of materials used for such an optical multilayer interference film are given below. In addition, the numerical value in the parenthesis following the chemical formula indicates each refractive index n.

First, 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 (2.0), WO ₃ (2.0), SiO (2.0), 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 (2.0), MgO ( 1.6), Si ₂ O ₂ (1.5), MgF ₂ (1.4), CeF ₃ (1.6), CaF ₂ (1.3 to 1.4), AlF ₃ (1.6) , Al ₂ O ₃ (1.6), GaO (1.7), and the like, and metal-based materials include Al, Fe, Mg, Zn, Au, Ag, Cr, Ni, Cu, Si Examples of simple metals or alloys such as That.

  Moreover, as a low refractive index material, for example, among organic polymers, polyethylene (1.51), polypropylene (1.49), polytetrafluoroethylene (1.35), polymethyl methacrylate (1.49), Polystyrene (1.60) and the like. However, the numerical value in parenthesis shows each refractive index n here. At least one kind is selected from these high refractive index materials or metal thin films having a light transmittance of 20 to 70%, and at least one kind is selected from low refractive index materials. Only a specific wavelength is absorbed or reflected.

  A multilayer thin film that generates optical wavelength interference is formed by laminating as a thin film by selecting from the above materials based on optical properties such as refractive index, reflectance, and transmittance, weather resistance, and interlayer adhesion. To do. As the forming method, a known method capable of controlling the film thickness, the film forming speed, the number of stacked layers, the optical film thickness, or the like can be used. For example, a vacuum deposition method, a sputtering method, a CVD method, or the like. The optical film thickness is an amount given by n · d, where n is the refractive index and d is the film thickness.

  In addition, the cholesteric liquid crystal layer has a helical structure in which the constituent molecules are optically active and nematically uniaxially oriented in the thin layer, but are twisted at a certain angle in a certain direction between adjacent layers. is doing. The pitch is distributed from several hundred nm to infinity. Due to this helical structure, the cholesteric liquid crystal selectively reflects light having a wavelength corresponding to the helical pitch and has a brilliant color from blue to red.

  Next, examples of the powder capable of seeing different colors depending on the observation angle include layered substances such as mica. A powder obtained by coating this mica with reduced titanium dioxide or iron oxide can be used. These exhibit chromatic dispersion performance by the so-called flip-flop effect. By forming these powders into ink and using a known printing method or coating method, a layer having wavelength dispersion performance can be formed.

(Light reflecting layer)
The light reflecting layers 4 and 7 do not have to be provided in direct contact with the diffractive structure forming layers 2 and 5. However, when the diffractive structure forming layers 2 and 5 are relief type diffraction gratings, the uneven pattern, that is, an embossed surface. 3 and 6 need to be provided in direct contact with the light reflecting layers 4 and 7. In this case, the light reflected by the light reflecting layers 4 and 7 is diffracted light.

  As the light reflection layers 4 and 7, a metal thin film can be preferably used in terms of high reflection luminance. Examples of the metal include Al, Sn, Cr, Ni, Cu, Au, and brass. And this metal thin film can be formed using a vacuum film-forming method. As the vacuum film forming method, a vacuum deposition method, a sputtering method, or the like can be applied, and the thickness may be controlled to about 1 to 1000 nm.

  Further, a transparent thin film having a high refractive index can be used as the light reflecting layers 4 and 7. This transparent thin film preferably has a refractive index greater than 0.2 by the refractive index of the diffractive structure forming layers 2 and 5, and is a thin film made of a transparent material having a refractive index of 2.0 or more, for example.

As such a transparent material, for example, Sb ₂ O ₃ (refractive index n = 3.0), Fe ₂ O ₃ (n = 2.7), TiO ₂ (n = 2.6), Cds (n = 2.6), CeO ₂ (n = 2.3), ZnS (n = 2.3), PbCl ₂ (n = 2.3), CdO (n = 2.2), Sb ₂ O ₃ (n = 2.0), WO ₃ (n = 2.0), SiO (n = 2.0), Si ₂ O ₃ (n = 2.5), In ₂ O ₃ (n = 2.0), PbO ( n = 2.6), Ta ₂ O ₃ (n = 2.4), ZnO (n = 2.1), ZrO ₂ (n = 2.0), and the like. Then, the thin film can be formed using a vacuum film forming method. The thickness of the thin film may be about 1 to 1000 nm.

  Alternatively, a thin film may be formed by printing ink containing metal powder or transparent material powder. In this case, the powder preferably has a particle diameter of 500 nm or less. The thickness of the thin film is preferably 0.1 to 20 μm, and a known printing method such as a gravure printing method, a flexographic printing method, or a screen printing method can be used as a printing method.

  The light reflecting layers 4 and 7 can be processed into image patterns by performing the following methods in separate steps.

  That is, the first method is a method using the above-described printing method. In the second method, the light reflecting layers 4 and 7 are vacuum-formed in each step by overlaying a mask having a pattern-shaped opening made of a predetermined image or the like on the diffraction structure forming layers 2 and 5. In this method, the light reflecting layers 4 and 7 are formed into an image pattern.

  In the third method, first, a solvent-soluble resin layer is provided in a negative pattern, and the light-reflective layers 4 and 7 are uniformly formed on the entire surface by covering the solvent-soluble resin layer. The solvent-soluble resin layer is dissolved and removed at the same time, and at the same time, the light-reflecting layers 4 and 7 stacked on the solvent-soluble resin layer are removed, so that the remaining light-reflecting layers 4 and 7 are predetermined. This is a method of forming a pattern made of an image or the like.

  In the fourth method, first, on the diffractive structure forming layers 2 and 5, a resin layer that is easily peeled off from the diffractive structure forming layers 2 and 5 is provided in a negative pattern, and this resin layer is covered. After the light reflecting layers 4 and 7 are uniformly formed on the entire surface, the light reflecting layers 4 and 7 are removed by being transferred to an adhesive roll or an adhesive paper in a negative pattern by pressing against the adhesive roll or the adhesive paper. 7 is a method in which each image pattern remains.

  In the fifth method, the light reflecting layers 4 and 7 are uniformly formed on the entire surface, a chemical-resistant resin layer is provided on the light reflecting layers 4 and 7 in an image pattern, and alkaline or acidic etching is performed. In this method, the light reflection layers 4 and 7 exposed by applying a liquid are dissolved and removed. In this case, the light-reflective layers 4 and 7 may be processed into an image pattern, and then the chemical-resistant resin layer may be removed, but it is left as it is and used as a protective layer for imparting chemical resistance. You can also do it.

In the sixth method, a photosensitive resin layer is formed on the light reflection layers 4 and 7 formed uniformly on the entire surface, exposed and developed in a pattern, and then an alkaline or acidic etching solution is applied. In this method, the exposed light reflecting layers 4 and 7 are dissolved and removed. Also in this case, the remaining photosensitive resin layer can be left as it is, and can be used as a protective layer for imparting chemical resistance.
The seventh method is a method in which the remaining light reflection layers 4 and 7 are patterned by irradiating the light reflection layers 4 and 7 formed uniformly on the entire surface with laser light. .

  This pattern may be a random pattern that does not have a clear meaning. However, as a pattern such as a picture, a figure, a pattern, a character, a number, or a symbol, recognizable information may be given to the pattern made of this image. Is possible. However, it is necessary that the image patterns exist in an independent state and that the patterns are electrically insulated from each other.

  The protective layer 8 may be a thermoplastic resin, a thermosetting resin, a moisture curable resin, an ultraviolet curable resin, an electron beam curable resin, or the like. For example, acrylic resin, polyester resin, and polyamideimide resin. When a lubricant is added to prevent damage, polyethylene powder or wax such as carnauba wax can be used as a lubricant, and up to 20 parts by weight can be added. These are formed as the protective layer 8 on the light reflection layer 7 by a known coating method such as a gravure printing method or a micro gravure method.

[Forgery prevention medium]
The anti-counterfeit medium 30 can be manufactured by directly printing on the base material and the protective layer of the diffractive structure according to the present invention by a known printing method such as an offset printing method or a screen printing method to obtain a desired size. I can do it.

[Forgery prevention paper]
Further, the diffractive structure of the present invention is formed by a known paper machine so that both the front and back surfaces of the diffractive structure are exposed simultaneously or alternately on the surface of the paper in the paper making process when manufacturing the paper. Thus, the forgery prevention paper 40 can be manufactured.

  Specific examples of the present invention will be described below.

<Example 1>
A transparent polyethylene terephthalate (commonly known as PET) film having a thickness of 250 μm was used as the base material 1 shown in FIG. 1, and an ink composed of the following composition was applied and dried on one side to form a layer having a thickness of 1 μm. Thereafter, a press plate for forming a diffraction grating was hot-pressed by a roll embossing method to form an embossed surface 3 for generating a diffraction grating on the surface thereof, and a diffraction structure forming layer 2 was obtained.

  An aluminum vapor deposition film is uniformly formed with a film thickness of 50 nm on the entire surface of the diffractive structure forming layer 2 by vacuum vapor deposition to form a thin film of the light reflecting layer 4, and the diffractive structure is formed on the light reflecting layer 4. The diffraction structure forming layer 5, the embossed surface 6, and the light reflecting layer 7 were laminated in the same manner and thickness as the layer 2, the embossed surface 3, and the light reflecting layer 4.

  Further, on the light reflection layer 7 obtained above, an ink comprising the following composition was applied and dried, and a protective layer 8 having a thickness of 2 μm was laminated, and the diffractive structure 20 of the first invention shown in FIG. Manufactured.

"Ink composition for diffraction structure forming layer"
Urethane resin 20.0 parts by weight Methyl ethyl ketone 50.0 parts by weight Ethyl acetate 30.0 parts by weight “Ink composition for protective layer”
Polyamideimide resin 19.5 parts by weight Carbana wax 0,5 parts by weight Dimethylacetamide 55.0 parts by weight Toluene 25.0 parts by weight Next, an offset is made on the surface of the base material 1 on the back side of the diffraction structure 20 obtained above. A desired anti-counterfeit medium 30 shown in FIG. 4 was manufactured by printing characters and designs by a printing method and punching them into an arbitrary shape.

  The anti-counterfeit medium 30 manufactured in the first embodiment includes a diffractive structure that generates diffracted light that allows different colors and images to be seen depending on the viewing angle, and the diffractive structure is anti-counterfeit. Not only from the front side of the medium but also from the back side, the colors and images of the diffracted light can be seen depending on the viewing angle, and the diffractive structure is directly laminated on the base material, so that counterfeiting and tampering are possible. It could be a difficult anti-counterfeit medium.

<Example 2>
As a base material 1 shown in FIG. 1, a transparent polyethylene terephthalate film having a thickness of 12 μm is used, and on one side thereof, an ink composed of the following composition is applied and dried to form a layer having a thickness of 0.5 μm. A press plate for forming a diffraction grating was hot-pressed by a roll embossing method to form an embossed surface 3 for generating a diffraction grating on the surface, thereby forming a diffraction structure forming layer 2.

  Next, an aluminum vapor deposition film is uniformly formed with a film thickness of 50 nm on the entire embossed surface 3 of the diffractive structure forming layer 2 by a vacuum vapor deposition method to form a thin film of the light reflection layer 4. The diffraction structure forming layer 5, the embossing 6, and the light reflecting layer 7 are laminated on the diffraction structure forming layer 2, the emboss forming surface 3 and the light reflecting layer 4 in the same manner and with a film thickness. On top of this, an ink composed of the following composition was applied and dried, and a protective layer 8 having a thickness of 1 μm was laminated to produce the diffractive structure 20 of the first invention shown in FIG.

"Ink composition for diffraction structure forming layer"
Urethane resin 20.0 parts by weight Methyl ethyl ketone 50.0 parts by weight Ethyl acetate 30.0 parts by weight “Ink composition for protective layer”
Polyamideimide resin 20.0 parts by weight Dimethylacetamide 45.0 parts by weight Toluene 35.0 parts by weight On both sides of the diffractive structure 20 obtained above, an adhesive for improving adhesion to paper fibers during papermaking (The material is not limited here, but it is desirable that the material has high transparency) by 1 μm by gravure printing method, slitting to 5 mm width, and 5 mm width slit to which this adhesive is applied The diffractive structure 20a is made by using a circular paper machine so that the front and back are alternately exposed to form a threaded paper, and cut into an arbitrary size as shown in FIG. Manufactured.

  The anti-counterfeit paper 40 manufactured in Example 2 has a thread-like diffractive structure that generates diffracted light that allows different colors and images to be seen depending on the viewing angle. The diffractive structure is exposed on both the front and back surfaces of the anti-counterfeit medium, and the colors and images of the diffracted light can be seen depending on the viewing angle, and further, counterfeiting and alteration are difficult due to the incorporation.

It is explanatory drawing which represented one example of the diffraction structure of this invention with the side cross section. It is explanatory drawing which represented the case where a diffracted light generate | occur | produces in the front and back of one case of the diffraction structure of this invention with the side cross section. It is explanatory drawing which represented the other example of the diffraction structure of this invention with the side cross section. It is explanatory drawing which represented one example of the forgery prevention medium using the diffraction structure of this invention by the side cross section. It is a sectional side view explaining other 1 example of the forgery prevention medium using the diffraction structure of this invention. It is a sectional side view explaining other 1 example of the forgery prevention medium using the diffraction structure of this invention. It is a front view explaining one example of the forgery prevention paper using the diffraction structure of the present invention. It is sectional drawing showing the AA surface of FIG. It is sectional drawing showing the BB surface of FIG. It is a front view explaining one example of the forgery prevention paper using the diffraction structure of the present invention. It is sectional drawing showing the AA surface of FIG. It is sectional drawing showing the BB surface of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Diffraction structure formation layer 3 ... Embossed surface which is diffractive structure 4 ... Light reflection layer 5 ... Diffraction structure formation layer 6 ... Embossed surface which is diffractive structure 7 ... Light reflection Layer 8 ... Protective layer 9 ... Print layer 10 ... Magnetic tape 11 ... Paper 12 ... Image pattern 13 ... IC chip 14 ... Antenna 15 ... Non-contact IC inlet 20 ... Diffraction structure 20a ... Slit diffraction structure 30 ... Anti-counterfeit medium 40 ... Anti-counterfeit paper

Claims (9)

  A diffractive structure in which a plurality of diffractive structure forming layers in which different diffractive structures are formed are laminated on the entire surface or a part of one surface of a transparent substrate, and at least the first diffractive structure in which the diffractive structure is formed A structure forming layer, a light reflecting layer, a second diffractive structure forming layer in which a diffractive structure different from the first diffractive structure forming layer is formed, and a light reflecting layer are sequentially stacked. Diffractive structure.   The diffractive structure according to claim 1, wherein the transparent substrate includes a plurality of layers having different refractive indexes.   The diffractive structure according to claim 1, wherein a colored image pattern is printed on at least one surface of the transparent substrate.   The diffractive structure according to claim 1, wherein the diffractive structure is a diffraction grating that diffracts only an arbitrary specific wavelength.   The diffractive structure according to any one of claims 1 to 4, wherein the light reflecting layer is partially patterned and laminated on the diffractive structure forming layer.   Among the light reflecting layers, a transparent protective layer that protects the light reflecting layer on the light reflecting layer exposed on the outermost surface and / or each layer between the base material, the diffraction structure forming layer, and the light reflecting layer. 6. The diffractive structure according to any one of claims 1 to 5, further comprising an adhesion auxiliary layer that enhances adhesion.   An anti-counterfeit medium using the diffractive structure according to any one of claims 1 to 6, wherein a pattern, characters, and / or information are provided on a surface of the transparent substrate constituting the diffractive structure without a diffractive structure forming layer. An anti-counterfeit medium characterized by being provided with a recording medium.   The anti-counterfeit medium using the diffractive structure according to any one of claims 1 to 6, wherein a surface of the transparent base material constituting the diffractive structure without the diffractive structure forming layer is a transparent article that requires anti-counterfeiting. An anti-counterfeit medium characterized by being applied.   An anti-counterfeit paper using the diffractive structure according to any one of claims 1 to 6, wherein the anti-counterfeit paper is made or pasted on the paper.

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