JP5633391B2 - Anti-counterfeit medium having metal thin film layer and anti-counterfeit paper - Google Patents

Description

  The present invention relates to a forgery prevention medium and a forgery prevention sheet having a metal thin film layer having a forgery prevention function for making forgery or tampering difficult.

  Conventionally, for example, means for preventing counterfeiting of banknotes, stock certificates, etc., have been made difficult by imitating the article itself, or by attaching an article that is difficult to imitate to the article as authentic proof. There is something that makes it possible to judge. For example, the former, like securities such as banknotes and stock certificates, must be finely printed or watermarked on itself, or used in colors that are difficult to reproduce, or special on the material itself. As a result, counterfeiting by printing technology and counterfeiting 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).

  In such a diffractive structure, a reflective layer is usually provided so as to be in contact with the diffractive structure in order to make the optical effect of diffraction easily visible. This is to allow the observer to visually recognize the diffracted light by reflecting the diffracted light generated when the light enters the diffractive structure.

  In general, the reflective layer used for diffractive structures is a thin metal film, a printed layer with metallic luster ink, or a transparent metal thin film or inorganic compound thin film that combines transparency and reflectivity. Is used (see, for example, Patent Document 3).

  In addition, recently, the reflective layer has been complicated in structure and manufacturing method, such as removing a part of the reflective layer or providing a plurality of thin film layers made of a metal thin film layer or an inorganic compound. There is also a medium for preventing forgery that is more difficult to forge while being enlarged (for example, see Patent Document 4).

  In these conventional reflective layers, the film thickness is almost constant to stabilize the optical effect of the anti-counterfeit medium regardless of the type of material and the shape provided. And the presence or absence of an ink layer having an inorganic compound or metallic luster.

Japanese Patent No. 1615000 JP-A-4-149585 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.

  Even today, when the general public makes authenticity judgments on securities and banknotes, paper watermarks are effective and actually used, but in Japan, watermark papers produced by private companies have two gradations. The watermark paper having a plurality of gradations is used only for banknotes.

  Therefore, the present invention solves the above-mentioned problems of the prior art, and the object is to achieve the effect of a watermark having a plurality of gradations by controlling the thickness of the metal thin film layer rather than the paper watermark technique. By changing the metal thin film continuously to an arbitrary thickness so as to have multiple gradations, the specular reflection produces a shiny metallic luster and allows light to pass through in a backlight environment. It is an object of the present invention to provide a unique anti-counterfeit medium and anti-counterfeit paper that allows the transmitted light to be observed like letters and pictures by continuously changing the light transmittance according to the change in the film thickness.

  In addition, by using the metal thin film layer according to the present invention as a reflection layer of a diffractive structure, when the diffractive structure is observed in a light-illuminating environment behind the observer, In addition to observing light, when a diffractive structure is observed in a backlight environment, it is possible to observe characters and designs like a paper watermark by changing the transmission density of transmitted light. Therefore, it is possible to use a forgery prevention medium or a forgery prevention paper capable of authenticity determination.

  In the present invention, in order to achieve the above-mentioned object, first, in the invention of claim 1, the base material is made of a transparent material, and a metal thin film having a thickness of about 0 nm to 100 nm is formed on at least one surface of the base material or a part thereof. The thickness of the metal thin film layer is not constant but changes continuously, so that the transmitted light of the metal thin film can be observed like letters and pictures with continuous gradation. Is a medium for preventing forgery.

  Next, in the invention of claim 2, by having a colored layer composed of characters and patterns on the entire surface or a part between the base material and the metal thin film layer, the design property can be obtained in a normal forward light environment other than backlight. The anti-counterfeit medium according to claim 1, wherein the medium is provided.

  Further, in the invention of claim 3, another base material is laminated on the side of the base material having the metal thin film layer, and the metal thin film layer is sandwiched between the base materials, thereby improving the resistance while making it difficult to tamper with the metal thin film layer. The anti-counterfeit medium according to claim 1 or 2, wherein the forgery is prevented.

  According to a fourth aspect of the present invention, there is provided the forgery prevention medium according to any one of the first to third aspects, wherein an adhesion auxiliary layer is provided between any of the layers to improve interlayer adhesion. It is a thing.

  In the invention of claim 5, the substrate is made of an opaque material, and is formed of a metal thin film layer having a thickness of about 0 nm to 100 nm on the entire surface or a part of one surface of the substrate, and the thickness of the metal thin film layer is Since the visible light transmittance in the state of the anti-counterfeit medium after the base material alone or the base material is pasted together is 5% or more, when observing the transmitted light in a backlight environment, The medium is a forgery-preventing medium characterized by being able to observe characters, patterns, and the like due to changes in the thickness of the metal thin film layer.

  The invention according to claim 6 is the anti-counterfeit medium according to claim 5, wherein the opaque base material is made of a resin, and a printed layer is provided on the surface to form a card. .

  Next, the invention according to claim 7 is characterized in that a part of the base material has a window shape in an arbitrary shape, and a part of the metal thin film is exposed from the window opening part. The anti-counterfeit medium described in 5 or 6 is used.

  In the invention of claim 8, it is possible to observe colors and images on a certain range of angles on the transparent substrate, or a plurality of different colors and image patterns depending on the observation angles. A diffractive structure forming layer in which a diffractive structure that can be observed is laminated, and the metal thin film layer is laminated so as to be in contact with the diffractive structure forming layer to form a reflective layer having a diffractive structure. Item 5 is a forgery prevention medium according to any one of Items 1 to 4.

  In the invention of claim 9, it is possible to observe colors and images on a certain range of angles on the transparent substrate, or a plurality of different colors and image patterns depending on the observation angles. A diffractive structure forming layer on which a diffractive structure that can be observed is formed is laminated, and the metal thin film layer is laminated so as to be in contact with the diffractive structure forming layer to form a reflective layer of the diffractive structure. The anti-counterfeit medium according to any one of claims 1 to 4, wherein materials are laminated.

  The invention according to claim 10 provides the anti-counterfeit medium according to claim 8 or 9, wherein an adhesion auxiliary layer is provided between any of the layers.

  Next, in the invention of claim 11, the anti-counterfeit paper according to claim 5 or 6, wherein the opaque base material is made of synthetic paper which is a resin, and a printing layer is provided on the surface. It is.

  According to a twelfth aspect of the present invention, a part of the base material has a window opening shape in an arbitrary shape, and a part of the metal thin film is exposed from the window opening part. The anti-counterfeit paper described in 1. is used.

  By adopting the above configuration, the present invention has the following effects.

  That is, according to the first aspect of the present invention, the substrate is made of a transparent material, and a metal thin film layer is provided on the entire surface of at least one side of the substrate or a part thereof, and the thickness of the metal thin film layer is about 0 nm to By continuously changing within the range of 100 nm, it is possible to provide a forgery prevention medium in which the light transmitted through the metal thin film can be observed like a character or a pattern with continuous gradation.

  Further, according to the invention according to the second aspect, by having a colored layer composed of characters and pictures on the entire surface or a part between the base material and the metal thin film layer, in a normal follow light environment other than backlight. It can be set as a medium for preventing forgery having design properties.

  According to the third aspect of the present invention, another substrate is laminated on the surface of the substrate having the metal thin film layer, the metal thin film layer is sandwiched between the substrates, and the metal thin film layer is difficult to tamper with. It can be set as the forgery prevention medium which improved.

  According to the fourth aspect of the present invention, it is possible to provide a forgery prevention medium characterized in that an adhesion auxiliary layer is provided between any one of the above layers to improve interlayer adhesion and to further improve durability.

  According to the fifth aspect of the present invention, the base material is made of an opaque material, the metal thin film layer having a thickness of about 0 nm to 100 nm is formed on the entire surface or a part of one surface of the base material, and the metal thin film layer Since the thickness is not constant but continuously changes, and the visible light transmittance in the state of the forgery prevention medium after pasting the base material alone or the base material is 5% or more, the transmitted light in a backlight environment Can be obtained as a forgery-preventing medium characterized in that the transmitted light can be observed like a character or a pattern having continuous gradation by changing the film thickness of the metal thin film layer.

  According to the sixth aspect of the present invention, it is possible to provide a forgery prevention medium characterized in that the opaque base material is made of a resin and a printed layer is provided on the surface to form a card.

  According to the seventh aspect of the present invention, a part of the opaque base material has a window shape with an arbitrary shape, and a part of the metal thin film is exposed from the window opening portion. In addition to the watermark effect under the environment, even if the image is copied by a copier or scanner, the metallic luster due to the metal thin film layer exposed from the window opening cannot be reproduced. It can be used as a prevention medium.

  According to the invention of claim 8, the layer in contact with the metal thin film between the substrate and the metal thin film layer can observe colors and images at a certain range of angles, or It consists of a diffractive structure forming layer in which a diffractive structure capable of observing a plurality of different colors and image patterns according to the angle to be observed, and the metal thin film layer is a reflective layer having a diffractive structure. Anti-counterfeiting is characterized by being able to observe diffracted light in a light environment and observing letters and patterns due to light shading like a watermark with continuous gradation when light is transmitted in a backlight environment It can be a medium.

  According to the invention according to claim 9, the layer in contact with the metal thin film between the transparent base material and the metal thin film layer can observe colors and images at a certain range of angles, or It consists of a diffractive structure forming layer in which a diffractive structure capable of observing a plurality of different colors and image patterns according to the observation angle is formed, and the metal thin film layer is used as a reflective layer of the diffractive structure, and further on the reflective layer side Thus, a forgery prevention medium characterized in that a transparent or opaque base material is laminated.

  According to the tenth aspect of the present invention, it is possible to provide an anti-counterfeit medium characterized in that interlayer adhesion and fastness are improved by providing an adhesion auxiliary layer between any of the layers.

  According to the invention of claim 11, since the opaque base material is a synthetic paper that is a resin, the same printed expression as the paper is possible on the surface thereof, and the durability and printability of the synthetic paper are improved. It is possible to obtain a forgery-preventing paper characterized by having a watermark effect while being held.

  Further, according to the invention of claim 12, a part of the opaque base material has a window shape with an arbitrary shape, and a part of the metal thin film is exposed from the window opening part. In addition to the watermark effect in a backlight environment, the metallic luster due to the metal thin film layer exposed from the window opening cannot be reproduced even when copying images with a copier or scanner. It can be used as anti-counterfeit paper.

  As described above, the present invention provides a watermark function that has been the only anti-counterfeiting measure of paper only in the past, a film made of a polymer resin other than a paper base material, synthetic paper, and an anti-counterfeit medium having a diffraction structure. It is possible for anyone to easily determine the authenticity by the same method as the paper watermark.

  Therefore, the anti-counterfeit medium having a metal thin film with a continuously changing thickness according to the present invention can be used for a credit card or a magnetic card using plastic as a base material, a hologram that is an anti-counterfeit medium having a diffraction structure, or the like. Thus, it is possible to provide a forgery prevention medium capable of reliably determining authenticity while enhancing the forgery prevention effect.

It is a top view which shows the example of an image observed in the following light environment of the forgery prevention medium which concerns on the 1st example of this invention. It is a top view which shows the image observed in the backlight environment of the forgery prevention medium which concerns on the 1st example of this invention. It is AA sectional drawing of the forgery prevention medium shown in FIG. FIG. 2 is an optical path diagram of the anti-counterfeit medium in FIG. FIG. 3 is an optical path diagram of the anti-counterfeit medium in FIG. 2 under a backlight environment. It is sectional drawing of the forgery prevention medium which concerns on the 2nd example of this invention. FIG. 7 is an optical path diagram of the anti-counterfeit medium in FIG. FIG. 7 is an optical path diagram of the anti-counterfeit medium in FIG. 6 under a backlight environment. It is sectional drawing of the forgery prevention medium which concerns on the 3rd example of this invention, and the optical path figure in a backlit environment and a backlit environment. It is sectional drawing of the forgery prevention medium which concerns on the 4th example of this invention. FIG. 11 is an optical path diagram when the anti-counterfeit medium of FIG. 10 generates diffracted light in a normal light environment. FIG. 11 is an optical path diagram when the anti-counterfeit medium of FIG. 10 transmits light in a backlight environment. It is a figure which shows the example of a diffracted light image observed in FIG. 11, and the numerical example by metal luster. It is a figure which shows the example of an image by the transmitted light observed in FIG. 12, and a numerical example.

  Hereinafter, embodiments of the anti-counterfeit medium and the anti-counterfeit paper according to the present invention will be described in detail with reference to the drawings.

(First case)
FIG. 1 is a plan view of an anti-counterfeit medium 11 showing a first example of the present invention, and shows an image observed in a normal light environment.

  FIG. 2 shows a state where the forgery prevention medium 11 shown in FIG. 1 is observed in a backlight environment.

  3 is a cross-sectional view of the forgery prevention medium 11 taken along the line AA in FIG.

  As shown in FIGS. 1 to 3, the anti-counterfeit medium 11 is provided with a metal thin film layer 2 having a thickness of about 0 nm to 100 nm on one side of a transparent substrate 1. The character forming portion 2a is formed on the right side, and the forged discrimination portion 2b having a substantially square shape is formed on the right side.

  In the character forming portion 2a, the metal thin film layer 2 is provided on one side of the base material 1 with a predetermined character, for example, “10000” in the same film thickness. Further, the counterfeit discriminating section 2b is provided with the thickness of the metal thin film layer 2 continuously changing in a range of about 0 nm to 100 nm. As shown in FIG. Can be observed.

  The anti-counterfeit medium 11 configured as described above has a character shape of “10000” in the character forming portion 2a and a metallic luster due to the reflected light 23 in the forgery discrimination portion 2b as shown in FIG. You can observe.

  In addition, in the anti-counterfeit medium 11, a dark gray character “10000” can be seen through the character forming portion 2 a on the left side through the metal thin film layer 2 in a backlight environment as shown in FIG. On the other hand, in the portion of the forgery discrimination unit 2b provided on the right side portion, a difference occurs in the amount of transmitted light due to the change in the thickness of the metal thin film layer 2, so that a gradation is developed in the transmitted light 24 and a predetermined pattern is set. For example, the cherry blossom pattern can be observed.

  FIG. 4 is a diagram showing an optical path when the forgery prevention medium 11 of FIG. 3 is observed in a normal light environment. The light emitted from the light source 21 passes through the substrate 1 as incident light 22, is reflected by the metal thin film layer 2, and is then observed by the observer as reflected light 23.

  On the other hand, FIG. 5 is a diagram showing an optical path when the anti-counterfeit medium 11 of FIG. 3 is observed in a backlight environment. The light source 21 is located on the other side of the anti-counterfeit medium 11 when viewed from the observer, and light emitted from the light source 21 is incident as incident light 22 from the metal thin film layer 2 side of the anti-counterfeit medium 11. The light passes through the substrate 1 and is observed by the observer as transmitted light 24.

  In this way, the character forming portion 2a and the forgery discrimination portion 2b are observed to have a metallic luster due to the reflected light 23 in the following light environment, whereas the character forming portion 2a has the same transmission density of “10000” characters in the backlight environment. Then, the forgery discrimination unit 2b observes the cherry blossom pattern by the transmitted light 24 due to the light and shade according to the change of the transmission density. That is, in the forgery determination unit 2 b, the reflected light 23 and the transmitted light 24 are viewed differently.

(Second case)
FIG. 6 is a cross-sectional view of the forgery prevention medium 12 showing a second example of the present invention. After laminating the metal thin film layer 2 and the adhesion auxiliary layer 3 on one side of the substrate 1, the substrate 1 is further laminated, and as a result, the metal thin film layer 2 is sandwiched between the adhesion auxiliary layer 3 and the substrate 1. Since all the layers are in close contact with each other and the base 1 on the front and back sides has a structure that protects the metal thin film layer 2 from external threats, the anti-counterfeit medium 12 of this configuration has a strong structure in terms of resistance.

  FIG. 7 is a diagram showing an optical path when the forgery prevention medium 12 of FIG. 6 is observed in a normal light environment. The light emitted from the light source 21 passes through the substrate 1 as incident light 22, is reflected by the metal thin film layer 2, and is then observed by the observer as reflected light 23.

  FIG. 8 is a diagram showing an optical path when the forgery prevention medium 12 of FIG. 6 is observed in a backlight environment. The light source 21 is located on the other side of the anti-counterfeit medium 12 when viewed from the observer, and light emitted from the light source 21 enters the anti-counterfeit medium 12 as incident light 22, and the base material 1, the adhesion auxiliary layer 3, and the metal thin film The light passes through the layer 2 and the substrate 1 in this order, and is observed by the observer as transmitted light 24.

  Therefore, the metallic luster due to the reflected light 23 is observed in the character forming unit 2a and the forgery discrimination unit 2b in the normal light environment, while the “10000” character having the same transmission density in the character forming unit 2a and the forgery in the backlight environment. In the determination unit 2b, a cherry blossom pattern is observed by the transmitted light 24 depending on the density according to the change in the transmission density, and the reflected light 23 and the transmitted light 24 look different in the forgery determination unit 2b.

(Third case)
FIG. 9 is a cross-sectional view of the forgery prevention medium 13 showing a third example of the present invention. After providing the metal thin film layer 2 having a thickness of about 0 nm to 100 nm on one side of the opaque base material 1, the adhesion auxiliary layer 3 is laminated, and the opaque base material 1 is further laminated. In the present invention, the light transmittance in the visible light of the transmitted light 26, which is the light transmitted by the incident light 22 incident on the portion of the anti-counterfeit medium 13 where the metal thin film layer 2 is absent, is 5%. That's it.

  The anti-counterfeit medium 13 in FIG. 9 has the outermost surface of the front and back sandwiched between the opaque base materials 1, so that the metallic luster of the metal thin film layer 2 cannot be visually observed in a normal light environment, but the backlight environment Below, the light emitted from the light source 21 becomes incident light 22 and enters the anti-counterfeit medium 13 to become transmitted light 24 that is transmitted through the anti-counterfeit medium 13, and the character forming portion 2a has the same transmission density. For the “10000” character, the forgery determination unit 2b observes a pattern with shading according to a change in transmission density.

(Fourth case)
Although not shown in the figure here, the anti-counterfeiting measure, which is the fourth example of the present invention, is implemented by using a base made of a polymer resin for card as the opaque base 1 of the anti-counterfeit medium 13. Card.

(Fifth example)
In addition, when a synthetic paper having characteristics similar to paper is used for the opaque base material 1, it can be used as a forgery prevention paper which is the fifth example of the present invention.

(Sixth case)
Furthermore, when a window opening is provided on at least one side of the synthetic paper of the opaque base material 1 and the metal thin film layer 2 is exposed from the window opening, the anti-counterfeit paper according to the sixth example of the present invention is used. Can do.

(Seventh case)
FIG. 10 is a sectional view of the forgery prevention medium 14 showing a seventh example of the present invention. A diffractive structure forming layer 4 is laminated on one side of the substrate 1, and a diffractive structure 5 made of fine irregularities is formed on the diffractive structure forming layer 4. The metal thin film layer 2 is provided in a part in contact with the diffraction structure forming layer 4, and the adhesion auxiliary layer 3 and the base material 1 are sequentially laminated so as to cover the whole to form a forgery prevention medium 14.

  FIG. 11 shows an optical path when diffracted light appears when the anti-counterfeit medium 14 is observed in a normal light environment. The light generated from the light source 21 becomes incident light 22, enters the forgery prevention medium 14, passes through the base material 1, and is incident on the diffractive structure 5 formed on the metal thin film layer 2 side of the diffractive structure forming layer 4. Becomes the diffracted light 25, where the diffracted light 25 is reflected by the metal thin film layer 2 in contact with the diffractive structure forming layer 4, and the diffracted light 25 changes the traveling direction, and again causes the diffracted structure forming layer 4 and the substrate 1 to move. It penetrates and reaches the observer. FIG. 13 shows an example of numbers due to metallic luster in the character forming unit 2a and an example of a diffracted light image in the forgery discrimination unit 2b that are observed in the following light environment of FIG.

  FIG. 12 shows an optical path when transmitted light 24 is generated when the anti-counterfeit medium 14 is observed in a backlight environment.

  As shown in FIG. 12, in a backlit environment, the light source 21 is positioned on the other side of the anti-counterfeit medium 14, so that the incident light 22 is emitted from the substrate 1, the adhesion assisting layer 3, the metal thin film layer 2, and the diffractive structure forming layer. 4. The light passes through the base material 1 in this order to become transmitted light 24, and no diffracted light 25 is generated in a backlit environment, and the observer can observe only the transmitted light 24. FIG. 14 shows an example of numbers in the character forming unit 2a observed in the backlight environment of FIG. 12, and an example of an image by transmitted light in the forgery discrimination unit 2b.

  Hereinafter, the materials and forming methods of the respective layers constituting the anti-counterfeit medium and the anti-counterfeit paper according to the present invention will be described.

(Base material)
First, a resin film can be used as the substrate 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, since the heat resistance is high and the thickness is stable, a polyethylene terephthalate resin film can be preferably used.

  In addition, for these resin films, it is also possible to use films that have been subjected to processing such as antistatic treatment, mat processing, embossing, printing of characters and patterns, laser marking, etc. Arbitrary light transmittance can be obtained by mixing pigments, dyes, and other inorganic materials. However, in the present invention, the material and method for making the resin opaque are not particularly limited thereto.

(Metal thin film layer)
As the metal thin film layer 2, a metal thin film can be preferably used because of its high reflection luminance, easy film thickness control, and easy removal. Examples of such a 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 it is sufficient that the thickness can be controlled between 1 nm and 100 nm.

  And this metal thin film layer 2 is formed into a pattern shape when the metal thin film layer 2 is formed in a pattern shape with a constant film thickness by the following method, or is continuously changed and blurred. Can be processed.

  That is, the first method for forming the metal thin film layer 2 in a pattern with a constant film thickness is to form a vacuum film by overlaying a mask having a pattern-shaped opening on the diffraction structure forming layer 4. In this method, the metal thin film layer 2 is formed into a pattern.

  In the second method, first, a solvent-soluble resin layer is provided in a negative pattern, and the solvent-soluble resin layer is coated to form the metal thin film layer 2 uniformly over the entire surface. There is a method in which the remaining metal thin film layer 2 is formed in a pattern by removing the metal thin film layer 2 superimposed on the solvent soluble resin layer simultaneously with dissolving and removing the soluble resin layer.

  As a method of forming the metal thin film layer 2 in a pattern while continuously changing the film thickness, the metal thin film layer 2 is uniformly formed on the entire surface, and a chemical resistant resin layer is formed on the metal thin film layer 2. Is provided in a pattern, and the exposed metal thin film layer 2 is dissolved and removed by applying an alkaline or acidic etching solution. However, the chemical resistance of the resin layer in this case is such that the resin layer is gradually peeled off from the metal thin film layer 2 while being immersed in an alkaline or acidic etching solution. However, a resin layer that does not peel at all from the metal thin film layer 2 cannot be used.

  In addition, the second method of forming the metal thin film layer 2 in a pattern while continuously changing the thickness of the metal thin film layer 2 is to change the structure depth and the structure width of the diffraction structure 5 of the diffraction structure forming layer 4 formed on the substrate 1. If the metal thin film layer 2 is formed by a vacuum film forming method after being arbitrarily changed, there is a method in which the film thickness of the metal thin film layer 2 changes according to the structure depth and structure width of the diffraction structure 5.

  In the present invention, the method of forming the metal thin film layer 2 in a pattern or changing its thickness continuously is not limited to the above method, and these patterns have a clear meaning. Although it may be a random pattern having no symbol, it is also possible to give the observer recognizable information as a pattern such as a picture, a figure, a pattern, a character, a number, or a symbol.

(Adhesion auxiliary layer)
The adhesion auxiliary layer 3 is not particularly limited as long as it improves adhesion between the substrates 1, the substrate 1 and the metal thin film layer 2, and the diffractive structure forming layer 4. In particular, it is possible to use adhesive materials or adhesive materials based on resin materials such as vinyl chloride resin, acrylic resin, urethane resin, epoxy resin, silicon resin, etc. that have good adhesion, heat or photo-curing resin materials, etc. In addition, the transparency and opacity can be arbitrarily adjusted depending on the material added in addition to the resin material.

(Diffraction structure forming layer)
The diffractive structure forming layer 4 can be a diffractive structure such as a relief type diffraction grating or a volume type diffraction grating.

  The relief type diffraction grating has a diffraction grating recorded in the form of a fine uneven pattern on the surface thereof.

  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.

  As a method for recording an image pattern to be a folded lattice structure used in the present invention, a known hologram such as an image hologram, a Lippmann hologram, a rainbow hologram, and an integral hologram in addition to the two-beam interference method. It can be manufactured by this 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-shaped dot.

It is also possible to form the concavo-convex pattern by an induced surface relief forming method. That is, by irradiating an amorphous thin film of a polymer having azobenzene on the chain side with a relatively weak light of about several tens 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 on which the resin layer or the metal thin film layer 2 applied on the substrate 1 is formed, and a fine uneven pattern is transferred to the surface of the resin layer. The diffractive structure forming layer 4 can be obtained.

  As a resin applied to the diffraction structure forming layer 4 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.

  Further, as the diffractive structure forming layer 4, an optical multilayer interference film which is a multilayer thin film can also 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 a 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.

(Anti-counterfeit paper)
Further, in the anti-counterfeit medium of the present invention, the base material 1 can be made a forgery-preventing paper by using a thin resin film made of a known material, or a synthetic paper manufactured using a resin material as a raw material.

  Next, the present invention will be described by way of examples.

Example 1
First, the anti-counterfeit medium 11 having the metal thin film layer 2 whose thickness continuously changes, which is the first example, will be described. As the substrate 1, a transparent polyethylene terephthalate (commonly known as PET) film having a thickness of 250 μm was used.

  Next, after forming an aluminum vapor deposition film uniformly with a film thickness of 70 nm on one surface of the base material 1 by a vacuum vapor deposition method, a pattern resist ink composed of the following composition is applied using a spin coater method, The resist ink film having a thickness of 15 μm was formed by drying in a drying furnace at 100 ° C. for 5 minutes.

"Pattern resist ink"
Photoresist 30.0 parts by weight Toluene 10.0 parts by weight Methyl ethyl ketone 10.0 parts by weight Silica filler 1.5 parts by weight Next, it consists of negative characters and negative images of arbitrary density and images with negative type gradations. An exposure mask is brought into close contact with the resist ink film, exposure processing is performed using an ultraviolet irradiation apparatus with an exposure amount of 100 mJ / cm ² , and development processing is performed with a sodium hydroxide aqueous solution having a temperature of 35 ° C. and a concentration of 3%. Then, it was immersed as it was and the resist ink was peeled off at the same time. Further, after neutralizing with a 0.1% hydrochloric acid aqueous solution at normal temperature, it is washed with water and then naturally dried to form a metal thin film layer 2 in which the aluminum vapor deposition film continuously changes between 0 to 70 nm. The prevention medium 11 was produced.

  In the anti-counterfeit medium 11 thus produced, the luster of the aluminum metal is observed in the metal thin film layer 2 under normal normal light environment, and an image due to the film thickness difference of the metal thin film layer 2 is not observed at all. However, when the metal thin film layer 2 was observed in a backlight environment, an image based on the contrast of the transmission density could be clearly observed due to the difference in film thickness of the metal thin film layer 2.

(Example 2)
The anti-counterfeit paper in which the base material 1 is an opaque synthetic paper as the fifth example will be described. As the synthetic paper for the substrate 1, YUPO (manufactured by YUPO Corporation) having a thickness of 80 μm was used.

  Next, the adhesion auxiliary layer 3 made of the following composition was uniformly applied and dried on one side of the substrate 1 by a gravure printing method to form a thickness of 3.0 μm.

"Adhesion auxiliary layer 3"
Acrylic resin 20.0 parts by weight Toluene 40.0 parts by weight Methyl ethyl ketone 60.0 parts by weight Next, after an aluminum vapor-deposited film is uniformly formed at a film thickness of 70 nm by a vacuum vapor deposition method, a pattern resist ink comprising the following composition Was applied using a spin coater method and dried in a drying oven at a temperature of 100 ° C. for 5 minutes to form a resist ink film having a thickness of 15 μm.

"Pattern resist ink"
Photoresist 30.0 parts by weight Toluene 10.0 parts by weight Methyl ethyl ketone 10.0 parts by weight Silica filler 1.5 parts by weight Next, it consists of negative characters and negative images of arbitrary density and images with negative type gradations. An exposure mask is brought into close contact with the resist ink film, exposure processing is performed using an ultraviolet irradiation apparatus with an exposure amount of 100 mJ / cm ² , and development processing is performed with a sodium hydroxide aqueous solution having a temperature of 35 ° C. and a concentration of 3%. Then, it was immersed as it was and the resist ink was peeled off at the same time. Further, after neutralizing with a 0.1% hydrochloric acid aqueous solution at normal temperature, it was washed with water and then naturally dried to form a metal thin film layer 2 in which the aluminum deposited film continuously changed between 0 to 70 nm.

  Next, the adhesion auxiliary layer 3 was formed by the same composition ink and forming method, and then the same 80 μm synthetic paper as that of the substrate 1 was laminated by a hot roll press to produce a forgery prevention paper. Furthermore, the anti-counterfeit paper can be printed by a known printing method such as a gravure printing method, an offset printing method, or a screen printing method, and a desired anti-counterfeit paper can be produced by performing arbitrary printing. .

Example 3
The forgery prevention medium 14 having the diffractive structure and the metal thin film layer 2 whose thickness is continuously changed as the reflective layer of the diffractive structure, which is the aforementioned seventh example, will be described. As the substrate 1, a transparent polyethylene terephthalate (commonly known as PET) film having a thickness of 250 μm was used.

  First, an ink having the following composition is applied and dried by a gravure printing method to form a layer having a thickness of 1 μm, and then a press plate for forming a diffraction grating is hot-pressed by a roll embossing method to form a diffraction grating on the surface. Concavities and convexities for generating the diffractive structure forming layer 4 were formed.

"Diffraction structure forming layer ink composition"
Urethane resin 20.0 parts by weight Silicone additive 0.2 parts by weight Methyl ethyl ketone 50.0 parts by weight Ethyl acetate 30.0 parts by weight Next, an aluminum deposition film is formed on one side of the substrate 1 by a vacuum deposition method to a film thickness of 70 nm. Then, a pattern resist ink comprising the following composition was applied using a spin coater method and dried in a drying oven at a temperature of 100 ° C. for 5 minutes to form a resist ink film having a thickness of 15 μm.

"Pattern resist ink"
Photoresist 30.0 parts by weight Toluene 10.0 parts by weight Methyl ethyl ketone 10.0 parts by weight Silica filler 1.5 parts by weight Next, it consists of negative characters and negative images of arbitrary density and images with negative type gradations. An exposure mask is brought into close contact with the resist ink film, exposure processing is performed using an ultraviolet irradiation apparatus with an exposure amount of 100 mJ / cm ² , and development processing is performed with a sodium hydroxide aqueous solution having a temperature of 35 ° C. and a concentration of 3%. Then, it was immersed as it was and the resist ink was peeled off at the same time. Further, after neutralizing with a 0.1% hydrochloric acid aqueous solution at normal temperature, it was washed with water and then naturally dried to form a metal thin film layer 2 in which the aluminum deposited film continuously changed between 0 to 70 nm.

  Next, the adhesion auxiliary layer 3 composed of the following composition was uniformly applied and dried by a gravure printing method to form a thickness of 4.0 μm.

"Adhesion auxiliary layer 3"
Acrylic resin 20.0 parts by weight Toluene 40.0 parts by weight Methyl ethyl ketone 60.0 parts by weight Finally, the base material 1 was laminated by a hot roll press to produce a forgery prevention medium 14.

(Comparative Example 1)
As Comparative Example 1, an aluminum vapor deposition film is formed on one surface of the substrate 1 with a film thickness of 70 nm by a vacuum vapor deposition method, and then an unnecessary portion of the aluminum vapor deposition film is eliminated by a YAG laser to obtain an arbitrary shape. A metal thin film layer having a constant film pressure was obtained to produce a forgery prevention medium of the prior art.

(Comparative Example 2)
As Comparative Example 2, a conventional anti-counterfeit paper was prepared by using the same materials and methods as in Example 2 except that the metal thin film layer was formed by the same method as in Comparative Example 1.

(Comparative Example 3)
As Comparative Example 3, a conventional anti-counterfeit medium having a diffractive structure was produced by using the same materials and methods as in Example 3 except that the metal thin film layer was formed by the same method as in Comparative Examples 1 and 2.

  When the anti-counterfeit media of Example 1 and Comparative Example 1 are compared, both appear to be anti-counterfeit media having the same metallic luster of aluminum in a normal light environment. However, in the backlight environment, the anti-counterfeit medium of Comparative Example 1 can only be seen as the shadow of the metal thin film layer 2, but when the anti-counterfeit medium of Example 1 is similarly observed in the backlight environment, the metal thin film layer 2 is I could observe the image with gradation like a paper watermark.

  Hereinafter, when the anti-counterfeit paper of Example 2 and Comparative Example 2 and the anti-counterfeit medium of Example 3 and Comparative Example 3 were observed under a direct light environment and a back light environment, any anti-counterfeiting was observed under the normal light environment. The paper and the anti-counterfeit medium had the same visual effect, but only the anti-counterfeit paper of Example 2 and the anti-counterfeit medium of Example 3 of the present invention gave a gradation like a watermark to the metal thin film layer 2 in a backlight environment. I could observe the image I had.

  As described above, the anti-counterfeit medium and the anti-counterfeit paper of the present invention have the effect of the “watermark” which is the anti-counterfeit technology possessed only by the watermark paper, and the anti-counterfeit medium or anti-counterfeit paper made of a substrate other than paper. However, it has been confirmed that it has, and furthermore, it is easier to determine the authenticity, but makes it more difficult to forge or tamper.

  DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Metal thin film layer, 2a ... Character formation part, 2b ... Counterfeit discrimination | determination part, 3 ... Adhesion auxiliary | assistant layer, 4 ... Diffraction structure formation layer, 5 ... Diffraction structure (uneven part), 11 ... 1st Anti-counterfeit medium according to example, 12 ... Anti-counterfeit medium according to second example, 13 ... Anti-counterfeit medium according to third example, 14 ... Anti-counterfeit medium according to seventh example, 21 ... Light source, 22 ... Incident Light, 23 ... reflected light, 24 ... transmitted light, 25 ... diffracted light, 26 ... transmitted light in a portion without the metal thin film layer 2.

Claims (12)

The substrate is made of a transparent material, a metal thin film layer having a thickness of about 0 nm to 100 nm is formed on the entire surface or a part of at least one side of the substrate, and the thickness of the metal thin film layer is continuously changed , The film thickness difference in the metal thin film layer causes the transmitted light transmitted through the metal thin film layer to have a contrast due to the film thickness difference, and a preset image is formed with the contrast. An anti-counterfeit medium characterized by.   2. The medium for preventing forgery according to claim 1, further comprising a colored layer composed of characters and pictures on the entire surface or a part between the base material and the metal thin film layer.   The forgery prevention medium according to claim 1 or 2, wherein another base material is laminated on the side of the base material having the metal thin film layer, and the metal thin film layer is sandwiched between the base materials.   The forgery prevention medium according to any one of claims 1 to 3, wherein an adhesion auxiliary layer is provided between any of the layers.   A base material is made of an opaque material, and a metal thin film layer having a thickness of about 0 nm to 100 nm is formed on the entire surface or a part of one surface of the base material, and the thickness of the metal thin film layer is continuously changed. An anti-counterfeit medium, wherein the anti-counterfeit medium formed by bonding a single substance or a base material has a visible light transmittance of 5% or more.   6. The medium for preventing forgery according to claim 5, wherein the opaque base material is made of a resin, and a printed layer is provided on the surface to form a card.   The forgery prevention medium according to claim 5 or 6, wherein a part of the base material has a window shape with an arbitrary shape, and a part of the metal thin film is exposed from the window opening part.   A diffractive structure capable of observing colors and images at a certain range of angles on the transparent substrate, or observing a plurality of different colors and image patterns depending on the angle of observation. 5. The reflection layer having a diffractive structure, wherein the formed diffractive structure forming layer is laminated, and the metal thin film layer is laminated so as to be in contact with the diffractive structure forming layer. The medium for preventing forgery described in the paragraph.   A diffractive structure capable of observing colors and images at a certain range of angles on the transparent substrate, or observing a plurality of different colors and image patterns depending on the angle of observation. It is characterized by laminating the formed diffractive structure forming layer, laminating the metal thin film layer so as to be in contact with the diffractive structure forming layer to form a reflective layer of diffractive structure, and further laminating a transparent or opaque base material. The forgery prevention medium according to any one of claims 1 to 4.   The forgery prevention medium according to claim 8 or 9, wherein an adhesion auxiliary layer is provided between any of the layers.   The anti-counterfeit medium according to claim 5, wherein the opaque base material is made of synthetic paper made of a resin, and a printing layer is provided on a surface thereof.   The forgery prevention paper according to claim 11, wherein a part of the base material has a window shape with an arbitrary shape, and a part of the metal thin film is exposed from the window opening part.

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