JP2008083145A - Diffraction structure transfer foil and forgery prevention medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diffraction structure transfer foil which enables the observation of a diffraction light image by the incident light from a surface, generates the diffraction light by backlight due to the multiple recording of the diffraction grating pattern made even in the state of generation the backlight during such observation as incidence of the light from the rear of the diffraction structure, and allows the observation of the diffraction light from the surface of the diffraction structure, and to provide a forgery prevention medium. <P>SOLUTION: The diffraction structure transfer foil constituted by laminating four layers of at least a peeling protective layer, a diffraction structure forming layer, a transparent reflection layer, and an adhesive layer in this order viewed from a support side, is formed with the multiple recorded diffraction structure for generating the separate diffraction light in the case where the diffraction light generated by the incidence of the light is made incident on the diffraction structure forming layer from the peeling protective layer side and the case where the light is made incident from the adhesive layer side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transfer foil, and more particularly to a diffraction structure transfer foil having a forgery prevention function for making forgery or alteration difficult. By transferring the diffraction structure transfer foil of the present invention to a ticket, card, certificate, official document, or the like made of paper or plastic, an anti-counterfeit medium can be manufactured. This anti-counterfeit medium can be used for credit cards, securities, guarantees, certificates, etc., for example.

  Conventionally, the means for preventing counterfeiting is to make it difficult to imitate the article itself, or to attach an article that is difficult to imitate to the article as 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 become even finer, making duplication and forgery more difficult, but as the miniaturization progresses, authenticity cannot be determined at a glance, making it difficult to determine Absent.

  Therefore, it is possible to easily determine the authenticity at a glance by attaching it to an article, and since it is easy to handle, a diffraction structure in which a diffraction grating pattern is recorded has been widely used as a forgery prevention means. . Examples of the diffractive structure employed as such anti-counterfeiting means include, for example, a peelable layer having a peelability on a substrate, a diffraction structure forming layer having a diffraction grating formed thereon, and a reflective layer having a metallic luster next. In addition, there are a structure in which an adhesive layer is sequentially laminated to form a diffractive structure as a transfer foil, a structure in which a diffractive structure forming layer is provided directly on a substrate, and a reflective layer and an adhesive layer are sequentially laminated to form a sticker ( For example, see Patent Documents 1 and 2).

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

  A 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 a concavo-convex shape. Interference caused by the unevenness, and light generated by the interference (hereinafter referred to as reproduction light or reproduction image) reproduces arbitrary image information at a certain angle or within a certain range with respect to the incident light. It is. 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.

Also, as a reflective layer for reflecting the diffracted light generated by the diffraction grating, the reflective layer is formed by forming an inorganic compound thin film by depositing a transparent metal so as to be in contact with the lower side of the diffraction structure forming layer. Thus, the reproduced image can be observed at a certain angle or an angle within a certain range, and when the reproduced image is not observed, it is positioned below the reflective layer through the transparent diffraction grating and the reflective layer. Some of them can be visually observed (see, for example, Patent Document 3).
Each of these conventionally used diffractive structures generates a reconstructed image by diffracted light when light enters the diffractive structure forming layer from the observer side, and reflects the diffracted light by the reflective layer to the observer. The reconstructed image can be observed, and when a transparent reflective thin film is used for the reflective layer, when the reconstructed image is not observed, the layer located below the reflective layer can be observed as it is. It becomes like this. However, these reconstructed images by diffracted light can be observed only when light enters from the observer side.
Patent documents etc. are as follows.
JP-A-61-190369 Japanese Patent Publication No. 1-54709 Japanese Patent Laid-Open No. 11-91297

  However, even with a diffractive structure as a forgery prevention measure as described above, it is not possible to easily determine whether it is true or not at a glance due to progress in simplification and cost reduction of the manufacturing method of the diffractive structure. Counterfeiting of diffractive structures is increasing, and recently its anti-counterfeiting effect is fading.

  Also, when observing watermarks that are used to prevent forgery on securities and banknotes, the watermark part is made transparent in a so-called backlight condition, such as placing a watermark part of an anti-counterfeit medium between the observer and the light source. Observe the watermark pattern on the substrate, but when observing in such a backlit state or close to backlit state, a conventional diffractive structure observes a reconstructed image even if light enters the diffractive structure forming layer. The effect cannot be confirmed because the amount of light is less than the minimum required.

  Therefore, the present invention aims to further improve the anti-counterfeiting effect due to a new visual effect that is not found in the conventional diffractive structure, in which a reproduced image can be observed by diffracted light even in an environment that is close to or close to backlight. The function of being able to observe the diffracted light image by the incident light from the surface by diffracting the light incident from the surface, which is the same principle as the conventional one according to the above description, by the diffraction grating of the diffractive structure and reflecting it by the transparent reflective layer, Even in the state where light is incident from the back side of the diffractive structure, it is backlit at the time of observation, and a plurality of diffraction grating patterns are recorded on the diffractive structure forming layer. An object of the present invention is to provide a diffractive structure transfer foil having a unique diffraction grating pattern in which diffracted light can be observed from the surface of the diffractive structure.

  In addition, the present invention can transfer the diffractive structure transfer foil onto a transfer target substrate having optical transparency so that light can enter the diffractive structure forming layer from either the front surface or the back surface of the diffractive structure. Since diffracted light is generated, it is possible to obtain an anti-counterfeit effect regardless of the follow-up backlight.

  The invention according to claim 1 is a transfer foil having a transfer layer on one side of a support, transferring the transfer layer to a substrate to be transferred, and peeling and removing the support. A diffractive structure in which a diffractive structure capable of observing colors and images at a certain range of angles or observing a plurality of different colors and image patterns depending on the angle of observation And a transparent reflection layer that reflects a part of the light that has entered and transmitted through the diffraction structure formation layer, and when viewed from the support side, at least a peeling protective layer, a diffraction structure formation layer, a transparent reflection layer, Diffraction structure transfer foil in which four layers of adhesive layers are laminated in this order. Diffraction that generates a reconstructed image by diffracted light when entering from at least one of the peeling protective layer side or the adhesive layer side. Multiple lattice patterns are recorded This provides a diffractive structure transfer foil characterized by the above, so that not only when the light enters the diffractive structure forming layer from the peeling protective layer side but also in the backlit state where light enters from the adhesive layer side In this case, the observer can observe the reproduced image.

  Next, according to a second aspect of the present invention, the transparent reflective layer is made of a single metal and oxides or nitrides thereof, and is formed as a thin film having a thickness of 1 nm to 50 nm in order to provide light transmittance. The diffractive structure transfer foil according to claim 1, characterized in that:

  The invention according to claim 3 is the diffraction structure transfer foil according to claim 1, wherein the transparent reflection layer is formed of a thin film of a transparent inorganic compound having a refractive index different from that of the diffraction structure forming layer. It is.

  According to a fourth aspect of the present invention, in the diffractive structure according to the first aspect, the diffractive structure forming layer diffracts only an arbitrary specific wavelength and transmits other wavelengths without diffracting. Transfer foil.

  Next, the invention described in claim 5 peels and removes the support after the diffractive structure transfer foil according to any one of claims 1 to 4 is transferred to a substrate to be transferred such as paper, film or card. The anti-counterfeit medium is characterized in that at least a portion where the diffractive structure transfer foil is pasted on the substrate to be transferred, or the entire substrate to be transferred has light transmittance.

  Next, the invention described in claim 6 has a watermark pattern on the substrate to be transferred, and when the observer observes the watermark pattern on the substrate to be transferred, the watermark-receiving portion and the substrate to be transferred have light transparency. Diffracted light is generated when light incident on the transfer layer from the adhesive side passes through the diffractive structure forming layer, and the diffracted light and the watermark pattern of the transferred substrate are simultaneously or the transferred substrate. The anti-counterfeit medium according to claim 5, wherein the medium can be observed separately by changing the angle.

  According to the first aspect of the present invention, the interference fringes of the light that is the diffraction grating are recorded on the diffractive structure forming layer by the relief of the unevenness, and diffracted light is generated when the light enters here, Different colors and image patterns can be observed according to the angle at which the diffracted light becomes a reproduced image. Furthermore, the diffractive structure of the present invention is a diffraction grating in a multiplex recording state so that an observer can observe a reproduced image regardless of whether light enters from the front or back surface of the diffractive structure forming layer. When the light is incident from the structure forming layer side, the generated diffracted light is reflected by the transparent reflecting layer, and the diffractive structure is in the backlight state as viewed from the observer who enters the light from the opposite surface of the diffractive structure forming layer. Sometimes, diffracted light is generated toward the viewer side, so that it is possible to obtain the visual effect of the diffracted light regardless of the lighting environment of the diffractive structure.

  According to the second aspect of the present invention, the transparent reflective layer is formed of a metal thin film, and the thin film is formed with a thickness of 1 nm to 50 nm in order to achieve both light reflectivity and transparency.

  This is because if the thickness is less than 1 nm, the metal film is too thin and the reflectivity is almost lost. If the thickness is more than 50 nm, the light transmittance is remarkably lowered, and the diffracted light from the incident light from the adhesive layer cannot be observed. This is a limited edition.

  According to the third aspect of the present invention, the transparent reflective layer is not a metal reflective layer, but a transparent reflective layer formed by forming an inorganic compound having a refractive index different from that of the diffraction structure forming layer into a thin film. Since the compound has properties superior to those of metal materials in terms of chemical resistance, it is possible to improve resistance.

  According to the fourth aspect of the present invention, by limiting the wavelength region of the recording light when recording different colors and images as the diffraction grating pattern, the diffraction light generated when the light is incident on the diffraction structure forming layer can be obtained. By limiting the wavelength, the diffractive structure forming layer in the diffractive structure transfer foil can diffract only an arbitrary specific wavelength.

  According to the fifth aspect of the present invention, the diffractive structure transfer foil according to any one of the first to fourth aspects is transferred to a transfer-receiving substrate having light transmission, so that light passes through the transfer-receiving substrate and the adhesive layer. Therefore, it is possible to enter the diffractive structure forming layer, and therefore, the diffracted light is generated by both the light in the forward light state incident from the peeling protective layer side and the light in the back light state incident through the transfer substrate. The diffracted light can be observed from the peeling protective layer side. The transferred substrate used in the present invention can perform its function as long as the portion to be transferred has light transmittance. Therefore, the transferred substrate is the entire transferred substrate or a part of the transferred substrate. It suffices if the part has optical transparency.

  According to the invention described in claim 6, when the substrate to be transferred has a watermark pattern, when the observer observes the watermark pattern on the substrate to be transferred, the watermark portion and the substrate to be transferred having light transmittance are removed. Diffracted light is generated when light that is transmitted and incident from the adhesive side of the transfer layer passes through the diffractive structure forming layer, and the diffracted light and the watermark pattern of the transferred substrate are simultaneously or Since it can be observed separately by changing the angle, it is possible to obtain a novel visual effect that did not exist in the past and to further enhance the anti-counterfeit effect.

  The diffractive structure transfer foil according to the present invention includes a transfer foil support and a transfer layer. The transfer layer includes a diffractive structure forming layer and is transferred to a transfer substrate to prevent forgery of the transfer object. The support holds the transfer layer until transfer, and is peeled off after transfer.

  The transfer layer has at least a diffractive structure forming layer, a transparent reflective layer, and an adhesive layer in addition to the release protective layer. In this diffractive structure forming layer, light interference fringes, which are diffraction gratings, are recorded by concave and convex reliefs. In the present invention, diffracted light is generated even if light is incident from the front or back side of the diffractive structure forming layer. The diffraction grating pattern is recorded in multiple.

  Next, the transparent reflective layer is formed between the diffractive structure forming layer and the adhesive layer, so that printing or watermarks below the adhesive layer can be observed depending on the observation angle, and diffraction is possible at another angle. In order to be able to observe light colors and images, it is composed of a 1 to 50 nm metal thin film or a transparent inorganic compound thin film having a refractive index different from that of the diffraction structure forming layer in order to achieve both transparency and reflectivity. The

  The adhesive layer is a layer for adhering the transfer layer to the substrate to be transferred, and the material is not particularly limited as long as the transfer layer is in close contact with the substrate to be transferred. The adhesive layer used may be used.

  The transfer foil of the present invention may have another layer in the transfer layer in addition to the peeling protective layer, the diffraction structure forming layer, the transparent reflective layer, and the adhesive layer. For example, an anchor layer for improving the interlayer adhesion of each layer, a colored layer for coloring a reproduced image by diffracted light, printing, a watermark pattern, or the like can be used.

  In addition, when the transparent reflective layer is composed of a metal thin film, the transfer foil is provided with a protective layer having excellent chemical resistance in order to protect the transparent reflective layer from acid and alkali. Durability can also be improved.

  Next, the structure of the transfer foil according to the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view showing an example of a diffraction structure transfer foil according to the present invention. This diffractive structure transfer foil is composed of a support 1 and a transfer layer 10 laminated on one side of the support 1, and the materials, production methods, etc., from the first example to the fourth example of the present invention. Are different, but the layer structure is the same.

  The transfer layer 10 includes a peeling protective layer 2 that facilitates peeling from the support after transfer and protects the diffraction structure forming layer 3 from abrasion and the like after transfer in the layer configuration.

  In addition, the transfer layer 10 has a diffractive structure forming layer 3 in its layer structure, and a relief by unevenness is formed on one side of the diffractive structure forming layer 3 by embossing. A transparent reflective layer 4 is formed so as to be in contact therewith.

  In addition to this, the transfer layer includes an adhesive layer 5.

  The stacking order of these layers is, in order from the support 1 side, the peeling protective layer 2, the diffraction structure forming layer 3, the transparent reflective layer 4, and the adhesive layer 5.

  Next, FIG. 2 is a cross-sectional view showing a sixth example of the present invention. By transferring the diffraction structure transfer foil of the present invention to a paper base 6 having a watermark pattern 62 and peeling the support 1, The medium is a forgery prevention medium having a diffractive structure. Although not shown, a separate printing layer may be provided on the watermark portion, and if the portion to which the diffractive structure transfer foil on the paper base 6 is transferred is light transmissive, the watermark pattern 62 may be omitted. good. In the former case, it is possible to observe the color and the image by the diffracted light at a certain angle, and it is also possible to simultaneously observe the watermark pattern and the printed pattern at another angle. In the latter case, the watermark pattern or print pattern is not observed, and the medium becomes a forgery-preventing medium that can observe colors and images by diffracted light at a certain angle.

  The material and forming method of each layer constituting this transfer sheet will be described.

  First, a resin film can be used as the support 1. As the resin film, a polyethylene terephthalate resin film, a polyethylene naphthalate resin film, a polyimide resin film, a polyethylene resin film, a polypropylene resin film, a heat-resistant vinyl chloride film, or the like can be used. Among these resins, a polyethylene terephthalate resin film having high heat resistance and stable thickness can be preferably used.

  Moreover, the film which adjusted the peeling strength of the peeling protection layer 2 by providing a peeling layer in these resin films, or performing an easily bonding process can also be utilized as the support body 1. FIG. In addition, a film that has been subjected to processing such as antistatic treatment, mat processing, embossing, or the like can also be used.

  As the peeling protection layer 2, a resin added with a lubricant can be used. As the resin, a thermoplastic resin, a thermosetting resin, a moisture curable resin, an ultraviolet curable resin, an electron beam curable resin, or the like can be used. For example, acrylic resin, polyester resin, and polyamideimide resin. As the lubricant, wax such as polyethylene powder or carnauba wax can be used, and it can be added up to 20 parts by weight. These are formed as a peeling protective layer 2 on the support 1 by a known coating method such as a gravure printing method or a micro gravure printing method.

  The diffraction structure forming layer 3 may be a single layer of relief type diffraction grating, volume type diffraction grating, or the like, or a multilayer structure in which single layer diffraction gratings are appropriately laminated with appropriate film thicknesses.

  The relief type diffraction grating is a diffraction grating recorded in the form of a fine concavo-convex pattern on the surface. In the case of a single layer, the angle of the reference light or object light and the direction of irradiation are changed for a plurality of images. In the case of a multi-layer structure, each image pattern is recorded on each layer and laminated.

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.

  The details of the method for producing the diffraction grating structure used in the present invention will be described below in terms of the basic method for forming the diffraction structure forming layer as a single layer.

  First, separately from the material of the transfer foil of the present invention, a master plate that is the original plate of a diffraction grating that is a diffraction structure is prepared. As a method for producing this master plate, a photosensitive agent that is a recording layer for recording light on a transparent substrate such as a glass plate or a resin plate is uniformly applied by a known printing method such as a spin coater or a knife coater. Produced. Since this photosensitive agent needs to have a resolution that enables multiple recording, the resolution is desirably 2000 lines / mm or more.

  As the recording layer material, it is possible to use known materials such as silver salt emulsion, photoresist, dichromated gelatin, and photopolymer. These include the wavelength of the laser used for recording and multiple recording. The number of times of recording is determined as appropriate according to the recording method and the like.

  Next, as for the recording method, in the case of the photographing method, using the property of the diffraction grating capable of multiple recording, the object plate and the reference beam are separately irradiated from both the front and back sides of the master plate, and a plurality of images are sequentially applied. Record it. The diffraction gratings at this time are both transmissive diffraction gratings, but on the front and back surfaces, the reference light when the reproduction image by the reproduction light incident from the front surface is reflected by the reflection layer and the reproduction image from the back surface are used. Recording is performed by shifting the angle of the reference light so that the azimuth angles of the reference light do not coincide with each other, and a master plate is produced as a result.

  The recording of the diffraction grating on the master plate can also be made by a two-beam interference method. In the case of the two-beam interference method, the diffraction grating pattern may not be prepared by actual photographing or the like, but may be prepared by a computer synthesis method in which a diffraction grating pattern is prepared in advance by computer calculation. The diffraction grating pattern is created by calculating in advance with a computer so that an image pattern is generated by diffracted light regardless of whether light is incident from the front or back of the diffraction grating structure. It is produced by recording on the master version.

  Other methods such as image holograms, Lippmann holograms, rainbow holograms, and integral holograms can be used to produce holograms that have been known in the past. In this case, only the light incident from the surface is reproduced. Whereas the light is used as light (see FIG. 3), in the present invention, diffracted light by a diffractive structure such as a hologram or a diffraction grating is reproduced not only by light incident from the front surface but also by light transmitted from the rear surface. Therefore, in the present invention, even when a hologram is used, a master plate in which each image is recorded in a multiplexed manner is produced.

  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, an arbitrary three-dimensional image or changing image similar to a hologram can be recorded, and a diffraction grating pattern is produced by the above-described computer synthesis. It is also possible to use. 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-shaped 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. Then, the diffractive structure forming layer 3 can be formed by thermocompression bonding the press plate to the resin layer applied on the peeling protection layer 2 and transferring a fine uneven pattern on the surface of the resin layer. .

  As the resin applied to the diffraction structure forming layer 3 by the relief type diffraction grating, a thermoplastic resin, a thermosetting resin, an ultraviolet ray, an electron beam curable resin, 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.

  The transparent reflective layer 4 is preferably a metal thin film, but must have both reflective and transparent properties. Examples of the metal having such characteristics include Al, Sn, Cr, Ni, Cu, Au, and brass, and a metal thin film can be formed using a vacuum film forming method. As the vacuum film formation method, a vacuum deposition method, a sputtering method, or the like can be used, and it is desirable that the thickness having both transparency and reflectivity can be controlled to about 10 to 50 nm.

  A transparent thin film having a high refractive index can also be used as the transparent reflective layer 4. The transparent thin film is preferably made of a material such as a transparent resin, metal, metal oxide or the like having a refractive index greater than or equal to 0.2 higher than the refractive index of the diffractive structure forming layer 3, for example, a high refractive index having a refractive index of 2.0 or higher. Good material.

Examples of such a transparent high refractive index material include 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. And a thin film can be formed using a vacuum film-forming method. In this case, the thickness of the thin film may be about 5 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 determined in consideration of the light transmittance after printing, and is preferably 0.1 to 20 μm. The printing method is gravure printing, flexographic printing A known printing method such as a printing method or a screen printing method can be used.

  Any adhesive layer 5 may be used as long as it adheres to the substrate to be transferred by heat and pressure, and a known heat-sensitive adhesive material can be used.

The diffraction structure transfer foil according to the present invention is superposed on a light-transmitting portion on a substrate to be transferred and adhered by thermocompression bonding, and then the support 1 is peeled off to transfer the transfer layer, thereby preventing forgery. Media can be manufactured. Any material can be used as the substrate to be transferred. For example, a plastic card substrate made of polyvinyl chloride resin, polyester resin, polyethylene terephthalate resin, paper, synthetic paper, or the like can be used.

  The anti-counterfeit medium manufactured in this way has a diffractive structure that allows different colors and images to be seen depending on the viewing angle, and this diffractive structure has a light source behind the observer's head. In the normal light state, it is possible to observe the same reproduced image as a conventional diffractive structure having a reflective layer, but even in the backlit state where the light source is positioned ahead of the observer's head, As shown in FIG. 5, at a certain range of angles, a reproduced image by diffracted light can be observed by light transmitted through the transfer substrate 6 and the diffractive structure forming layer 3. In addition, when a watermark pattern is applied to the transferred substrate 6 as shown in FIG. 6, only the watermark pattern is observed at an angle where the diffracted light is not observed, but depending on the observation angle, the watermark pattern and the diffracted light are used. It is possible to observe colors and images at the same time, and to obtain a visual effect that has never existed before.

  Next, the present invention will be described by way of examples. The diffraction structure transfer foil of this example is the first example described above.

  First, a transparent polyethylene terephthalate (commonly known as PET) film having a thickness of 25 μm was used as the support 1.

  On one side of this support 1, an ink comprising the following composition was applied and dried to form a release protective layer 2 having a thickness of 2 μm.

  Next, an ink comprising the following composition is applied and dried to form a 1 μm-thick layer, and then a press plate for forming a diffraction grating is hot-pressed on the surface by a roll embossing method to form unevenness as a diffraction grating pattern. The diffractive structure forming layer 3 was formed.

  Next, an aluminum vapor deposition film was uniformly formed with a film thickness of 10 nm on the diffractive structure forming layer 3 by a vacuum vapor deposition method to obtain a transparent reflection layer 4.

  Next, an adhesive ink comprising the following composition was applied and dried to form an adhesive layer 5 having a thickness of 3 μm to produce a desired diffractive structure transfer foil.

"Peeling protective layer ink composition"
Polyamideimide resin 19.2 parts by weight Polyethylene powder 0.8 parts by weight Dimethylacetamide 45.0 parts by weight Toluene 35.0 parts by weight “Diffraction structure forming layer ink composition”
Urethane resin 20.0 parts by weight Methyl ethyl ketone 50.0 parts by weight Ethyl acetate 30.0 parts by weight “Adhesive layer ink composition”
Vinyl chloride vinyl acetate copolymer resin 15.0 parts by weight Acrylic resin 10.0 parts by weight Silica 1.0 part by weight Methyl ethyl ketone 44.0 parts by weight Toluene 30.0 parts by weight Next, this diffraction structure transfer foil was transferred to a group to be transferred. It was placed on the watermark portion applied to the paper, which was the material, and transferred with a hot roll transfer machine having a plate surface temperature of 120 ° C., and then the support 1 was peeled off to produce a forgery prevention medium.

  In the obtained anti-counterfeit medium, the watermark pattern cannot be observed in the forward light state where the light serving as the light source is located above or behind the observer, but a part of the light incident on the diffractive structure forming layer Was reflected by the transparent reflective layer, and the image by the diffracted light could be observed at a certain range of angles as in the conventional anti-counterfeit medium having a diffractive structure. Next, in order to observe the watermark pattern applied to the paper base material of the anti-counterfeit medium, when the light source is placed in front of the observer and the counterfeit prevention medium is placed between the light source and the observer, The surface of the anti-counterfeit medium becomes dark and the watermark pattern is observed.Furthermore, the image pattern changes depending on the observation angle, which is impossible with the conventional anti-counterfeit medium having a diffractive structure. Simultaneous observation was possible, and a reconstructed image by diffracted light under backlighting, which was impossible in the past, was confirmed.

It is sectional drawing which shows the 1st-4th example of the diffraction structure transfer foil which concerns on this invention. It is sectional drawing of the forgery prevention medium manufactured using the 1st-4th example of the diffraction structure transfer foil which concerns on this invention. It is a conceptual diagram of the reflection type diffraction grating used for the conventional diffraction structure. It is a conceptual diagram of the transmission type diffraction grating used for the diffraction structure concerning the present invention. FIG. 3 is a light path diagram when diffracted light is observed in the forgery prevention medium of FIG. 2. FIG. 3 is a light path diagram when only a watermark pattern applied to a paper base material is observed in the forgery prevention medium of FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ...... Transfer sheet support 2 ... Peeling protective layer 3 ... Diffraction structure forming layer 4 ... Transparent reflection layer 5 ... Adhesive layer 6 ... Transfer target group Material 10 ... Transfer layer 21 ... Incident light from front 22 ... Reflected diffracted light 31 ... Incident light from front 32 ... Reflected diffracted light 33 ... · Incident light from the back surface 34 ··· Transmitted diffracted light 41 ··· Transmitted light from the back surface 42 ··· Watermark pattern provided by the difference in paper thickness 43 ··· Transmission of the watermark pattern Light 51... Transmitted light from the back surface 52... Transmitted light that allows only a watermark pattern to be observed 62...

Claims (6)

  A transfer foil that has a transfer layer on one side of a support, transfers the transfer layer to a transfer substrate, and peels and removes the support. The transfer layer has a color within a certain range of angles. And a diffraction structure forming layer formed with a diffraction structure capable of observing a plurality of different colors and image patterns according to an observation angle, and the diffraction structure forming layer A transparent reflection layer that reflects a part of the light that has entered and transmitted, and when viewed from the support side, at least four layers of a peeling protective layer, a diffraction structure forming layer, a transparent reflection layer, and an adhesive layer are arranged in this order. It is a laminated diffractive structure transfer foil so that the diffracted light generated when light enters the diffractive structure forming layer generates diffracted light both when it enters from the peeling protective layer side and from the adhesive layer side. Multi-recorded diffraction structure is formed Diffraction structure transfer foil characterized.   2. The diffractive structure according to claim 1, wherein the transparent reflective layer is made of a single metal and its oxide or nitride, and is formed of a thin film having a thickness of 1 nm to 50 nm in order to provide light transmission. Transfer foil.   2. The diffractive structure transfer foil according to claim 1, wherein the transparent reflecting layer is formed of a transparent inorganic compound thin film having a refractive index different from that of the diffractive structure forming layer.   2. The diffractive structure transfer foil according to claim 1, wherein the diffractive structure forming layer diffracts only an arbitrary specific wavelength and transmits other wavelengths without diffracting.   The diffractive structure transfer foil according to any one of claims 1 to 4 is transferred to a substrate to be transferred such as paper, film, card, etc., and then the support is peeled and removed, at least the diffractive structure on the substrate to be transferred. An anti-counterfeit medium characterized in that a portion to which a transfer foil is affixed or the entire substrate to be transferred has light transmission properties.   It has a watermark pattern on the transfer substrate, and when the observer observes the watermark pattern on the transfer substrate, it passes through the watermark part and the transfer target substrate with light transmission and enters from the adhesive side of the transfer layer. The diffracted light is transmitted through the diffractive structure forming layer, and diffracted light is generated. The diffracted light and the watermark pattern of the transferred substrate can be observed simultaneously or separately by changing the angle of the transferred substrate. The forgery prevention medium according to claim 5.

Images