JP2018120010A - Color image print medium, article including the same, and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To print a color image on demand in a structure that displays the color image with a diffraction grating in a condition where a color image print medium is observed from an oblique direction.SOLUTION: A color image print medium has a marking layer that is typically transparent to a visible light area, and a relief structure forming layer provided with a printing area including a plurality of pixels laminated. The plurality of pixels provided in the printing area consist of at least three sub-cells, and are disposed such that colors emitted from the sub-cells have equal color intensities.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a structure based on an optical technique that provides an anti-counterfeit effect, a decorative effect, or an aesthetic effect, and more specifically, for forming an image of the structure on demand.

  In the fields of securities, certificates, branded products, dedicated consumables and dedicated replacement parts for electronic devices and various machines, and personal authentication media, it is desired that forgery or alteration is difficult. Therefore, in such a field, an optical structure excellent in the forgery prevention effect may be provided.

  Many of such optical structures include fine structures such as diffraction gratings, holograms, scattering structures, or lens arrays. These fine structures have an effect of causing a change in color or visual image in accordance with, for example, a change in observation angle.

  In addition, these fine structures are difficult to analyze, and forgery is difficult because they require expensive equipment such as an electron beam drawing apparatus to manufacture. Therefore, these optical structures can exhibit an excellent anti-counterfeit effect.

  As a technique related to such a structure, for example, Patent Document 1 proposes a technique in which a pixel is divided into three as an RGB channel and a photographic image quality color image is expressed by a diffractive structure by area gradation inside the channel. .

  Further, Patent Document 2 proposes a computer generated hologram that can display a full color pattern by providing each pixel of RGB in a long slit shape.

JP-A-8-211821 JP 2001-331085 A

  However, all of these structures need to form the desired image at the time of producing the original, and it has been difficult to form a relief structure having the same effect on demand.

  Accordingly, an object of the present invention is to form an arbitrary image on demand while maintaining the characteristic optical effect of a color hologram.

The present invention according to claim 1 for solving the above-described problem comprises a marking layer that is typically transparent in the visible light region and capable of laser printing, and a plurality of pixels in at least a part of the marking layer. A color image printing medium in which a relief structure forming layer having a printing area on its main surface is laminated at least, and each of the plurality of pixels provided in the printing area has at least three subcells, The two subcells are configured to display the first subcell configured to display red under the condition of observing from an oblique direction intersecting with the normal of the main surface of the relief structure forming layer, and to display green under the condition. The second subcell and a third subcell configured to display blue under the conditions, and the three colors have the same color intensity under the observation conditions. And a light reflecting layer is provided so as to cover at least part of the main surface of the relief structure forming layer and at least part of the printing area. It is.

  The invention according to claim 2 for solving the above problem is the color image printing medium according to claim 1, wherein the light reflecting layer is made of a metal thin film.

  The invention according to claim 3 for solving the above problem is the color image print medium according to claim 1 or 2, wherein the marking layer contains at least polycarbonate.

  An invention according to claim 4 for solving the above-mentioned problem is an article comprising the color image printing medium according to any one of claims 1 to 3.

  The invention according to claim 5 for solving the above-described problem is a marking layer that is typically transparent in the visible light region and capable of laser printing, and printing that includes a plurality of pixels on at least a part of the marking layer. A color image printing medium having at least a relief structure forming layer having a region on the main surface, wherein each of the plurality of pixels provided in the printing region has at least three subcells, The subcell is configured to display red under the condition that the subcell is observed from an oblique direction intersecting with the normal of the main surface of the relief structure forming layer, and to display green under the condition. The second subcell and the third subcell configured to display blue under the conditions, and the three colors have the same color intensity under the observation conditions. Should be printed on a color image printing medium provided with a light reflection layer so as to cover at least a part of the main surface of the relief structure forming layer and at least a part of the printing area. A printing method comprising a step of coloring a marking layer with a laser beam so as to block at least a part of light to be emitted from a corresponding subcell according to a color image.

  The invention according to claim 6 for solving the above problem is the printing method according to claim 5, wherein the color of the marking layer is black.

  According to a seventh aspect of the invention for solving the above-mentioned problem, at least a part of the light reflecting layer provided in the corresponding subcell is removed by laser light according to a color image to be printed, and the light reflecting layer is removed. The printing method according to claim 5, further comprising a step of forming a portion.

  The invention according to claim 8 for solving the above problem is characterized in that the position of the light reflecting layer removing portion and the position of the marking layer that develops color by laser light are synchronized. It is the printing method described.

  According to the aspect of the present invention, it is possible to form an arbitrary color image made of a relief structure having a high anti-counterfeit effect on demand.

It is a top view which shows an example of the color image printing medium which concerns on embodiment of this invention. It is sectional drawing which shows an example of a structure of the AA cut surface in FIG. It is a top view which shows an example of arrangement | positioning of the pixel in the printing area | region of this invention. It is a top view which shows an example of the structure of the pixel of this invention. It is a conceptual diagram which shows an example of the printing method of this invention. It is a top view of the pixel which shows the example of printing by FIG. 4 of this invention. It is a conceptual diagram which shows another example of the printing method of this invention. It is a top view of the pixel which shows the example of printing by FIG. 6 of this invention. It is sectional drawing which shows an example of the article | item provided with the color image printing medium of this invention.

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

  Each drawing shows one example of an embodiment of the present invention, and is not limited to these.

(Color image printing medium)
FIG. 1 is a plan view showing an example of a color image printing medium according to an embodiment of the present invention.

  In FIG. 1, a relief structure 20 is provided on the marking layer 10, and the relief structure 20 is provided with a light reflecting layer 23 at a part thereof, and further a part thereof is a print area 21. ing.

  Here, the light reflection layer 23 does not necessarily occupy one region in a pattern, and may be provided by being divided into a plurality of regions, and a portion provided in a stripe shape or a dot shape may be provided. There is no problem even if it is included. Further, it may be provided on the entire surface of the relief structure 20.

  The printing area 21 needs to be at least partially covered by the light reflection layer 23, and there is no problem even if the entire surface of the relief structure 20 is formed as the printing area 21.

  FIG. 2 is a cross-sectional view showing an example of the layer structure at the AA cut surface of the color image printing medium 1 of FIG.

  In FIG. 2, the relief structure 20 having a transfer foil configuration is illustrated, and the marking layer 10 is laminated via an adhesive layer 25.

  The relief structure 20 does not necessarily have a transfer foil structure, and a structure in which the relief structure forming layer 22 and the marking layer 10 formed on another support are stacked while holding the support (see FIG. (Not shown), or a structure (not shown) in which the relief structure forming layer 22 is directly provided on the marking layer 10 and an uneven structure is provided on the main surface thereof.

  Hereinafter, each configuration of FIG. 2 will be described.

  The marking layer 10 is a layer typically made of a transparent resin in the visible light region, and any conventionally known material can be used as long as it can be colored by laser light. The resin includes polyolefin resin, polyester resin, poly (meth) acrylic resin, polycarbonate resin, polyvinyl chloride fat, polystyrene resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polysulfone resin, urethane resin, epoxy resin. , Diallyl phthalate resin, melamine resin and the like can be used alone or as a composite. More preferably, it should contain at least a polycarbonate resin.

  To these resins, various additives such as color formers, dyes such as dyes and pigments, stabilizers and ultraviolet absorbers may be added to the extent that transparency is not impaired.

  As the color former, any conventionally known material can be used, but it is desirable to develop a black color, for example, a metal oxide that absorbs a laser beam and becomes colored by heat generated by photothermal conversion. Can do. Specifically, as a metal that forms a black oxide exhibiting good contrast, copper, iron, silver, platinum, nickel, manganese, titanium, lead, tin, chromium, cobalt, thallium, vanadium, niobium, tantalum Further, oxides made of metals such as tungsten, molybdenum, ruthenium, rhodium, rhenium, osmium, iridium, bismuth and palladium can be used singly or as a mixture or composite.

  The dye is preferably a material that absorbs laser light, and the surrounding resin can be carbonized by absorbing the laser light.

  Examples of such dyes include carbon black, cyanine dyes, polymethine dyes, anthraquinone dyes, phthalocyanine dyes, naphthalocyanine dyes, and the like.

Examples of lasers that perform printing on the marking layer as described above include a YAG laser, a YVO ₄ laser, and a carbon dioxide gas laser.

  When the relief structure 20 is configured as a transfer foil, it is arbitrarily selected from, for example, polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate, polyvinyl alcohol, polyolefin, triacetyl cellulose, polyvinyl chloride, papers, and the like. After the release layer 24 is applied on the base material and the relief structure forming layer 22 is applied, an uneven structure is formed on the main surface of the relief structure forming layer 22 by thermocompression bonding with an embossed plate having a pixel pattern to be described later. Then, it can be formed by providing the light reflecting layer 23 and applying the adhesive layer 25.

  Here, the release layer 24 is not necessarily provided, but is provided to facilitate the release of the relief structure forming layer 22 from the base material, and may be a conventionally known release layer material used for transfer foil or the like. Any of these resins can be used. Specifically, for example, various resins such as poly (meth) acrylic resin, polyester resin, polyvinyl chloride resin, epoxy resin, melamine resin, phenol resin, norbornene resin, and triacetyl cellulose resin. And natural or various synthetic waxes can be used alone or as a mixture, copolymer or composite.

  The relief structure forming layer 22 can use various resins such as a thermoplastic resin, a thermosetting resin, and a radiation curable resin.

  When a thermoplastic resin is used, for example, an acrylic resin, an epoxy resin, a cellulose resin, a vinyl resin, a mixture thereof, a copolymer thereof, or the like can be used.

  In the case of using a thermosetting resin, for example, a urethane resin, a melamine resin, or an epoxy resin formed by a crosslinking reaction between a polyol resin such as an acrylic polyol resin or a polyester polyol resin and an isocyanate compound. Phenolic resins, mixtures thereof, and copolymers thereof can be used.

  When using a radiation curable resin, the radiation curable resin typically includes a polymerizable compound and an initiator.

  As the polymerizable compound, for example, a compound capable of photo radical polymerization is used. Specifically, a monomer, oligomer or polymer having an ethylenically unsaturated bond or an ethylenically unsaturated group can be used. Alternatively, as a compound capable of radical photopolymerization, 1,6-hexanediol, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol acrylate, pentaerythritol tetraacrylate, pentaacethritol pentaacrylate and dipentaerythritol hexaacrylate Monomers such as epoxy acrylate, urethane acrylate and polyester acrylate, or polymers such as urethane-modified acrylic resin and epoxy-modified acrylic resin may be used.

  When a compound capable of photoradical polymerization is used as the polymerizable compound, a photoradical polymerization initiator can be used as the initiator.

  Examples of the photo radical polymerization initiator include benzoin compounds such as benzoin, benzoin methyl ether and benzoin ethyl ether, anthraquinone compounds such as anthraquinone and methylanthraquinone, acetophenone, diethoxyacetophenone, benzophenone, hydroxyacetophenone, 1-hydroxy Phenyl ketone compounds such as cyclohexyl phenyl ketone, α-aminoacetophenone and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, benzyldimethyl ketal, thioxanthone, acylphosphine oxide, or Michler's ketone, etc. can be used.

  Alternatively, a compound capable of photocationic polymerization may be used as the polymerizable compound. As the compound capable of photocationic polymerization, for example, a monomer, oligomer or polymer having an epoxy group, a xetane skeleton-containing compound, or vinyl ethers are used.

  When a compound capable of photocationic polymerization is used as the polymerizable compound, a photocationic polymerization initiator is used as the initiator. As this photocationic polymerization initiator, for example, an aromatic diazonium salt, an aromatic iodonium salt, an aromatic sulfonium salt, an aromatic phosphonium salt, or a mixed ligand metal salt is used.

  Alternatively, a mixture of a compound capable of photoradical polymerization and a compound capable of photocationic polymerization may be used as the polymerizable compound.

  In this case, as the initiator, for example, a mixture of a radical photopolymerization initiator and a cationic photopolymerization initiator is used. Alternatively, in this case, a polymerization initiator that can function as an initiator for both photoradical polymerization and photocationic polymerization may be used.

  As such an initiator, for example, an aromatic iodonium salt or an aromatic sulfonium salt is used.

  As an example in which a polymerization initiator is not used, a method of causing a polymerization reaction of a polymerizable compound by electron beam irradiation may be used.

  The radiation curable resin is a sensitizing dye, dye, pigment, polymerization inhibitor, leveling agent, antifoaming agent, sagging inhibitor, adhesion improver, coating surface modifier, plasticizer, nitrogen-containing compound, epoxy resin, etc. An additive, a release agent, or a combination thereof may further be included.

  The radiation curable resin may further contain a non-reactive resin in order to improve its moldability. As the non-reactive resin, for example, the thermoplastic resin, the thermosetting resin, or the like can be used alone or as a mixture.

  The light reflecting layer 23 is formed of a metal thin film layer in which a material typically made of metal is deposited.

  As a method of depositing a material made of metal, a known coating method or vapor deposition method capable of depositing the material so as to correspond to the surface shape of the relief structure forming layer 22 can be used.

  Examples of the coating method include a spray coating method. Examples of the vapor deposition method include a vacuum deposition method, a sputtering method, and a chemical vapor deposition method (CVD method). Among these, a vacuum vapor deposition method or a sputtering method is preferably used.

  Examples of the material for the metal thin film formed in this manner include metals such as Al, Sn, Cr, Ni, Cu, Au, and Ag, and metal materials selected from the group consisting of these alloys. Can do.

  Further, the light reflecting layer 23 made of the metal thin film as described above does not necessarily need to cover the entire surface of the relief structure forming layer 22. Even if it is provided in an arbitrary shape as necessary, there is no problem.

  Any conventionally known method can be used as the method for forming the light reflecting layer 23 made of the metal thin film layer into an arbitrary shape. As such an example, a mask printing layer is provided in a pattern on the light reflection layer 23 provided on the entire surface of the relief structure forming layer 22, and the metal in a region where the mask printing layer is not provided by an alkaline etching solution or the like. A method for etching a thin film can be exemplified.

  As the adhesive layer 25, a conventionally known adhesive such as a heat-sensitive adhesive or a pressure-sensitive adhesive can be arbitrarily used.

  Examples of the material used for the adhesive layer 25 include acrylic resins, polyester resins, polyvinyl chloride resins, vinyl chloride-vinyl acetate copolymers, polyolefin resins, chlorinated polyolefin resins, polyamide resins, urethane resins, ethylene- Various resins such as acrylic copolymer, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, rubbers, and the like can be used alone or as a mixture.

  In addition, for example, extender pigments such as titanium oxide, calcium carbonate, silica, talc, diatomaceous earth, and various waxes may be added to the adhesive layer 25.

  Here, a plurality of pixels PE are formed in the printing area 21 provided in the relief structure 20 as shown in FIG.

  In the example shown in FIG. 3, these pixels PE are arranged in a rectangular lattice shape along the X axis and the Y axis, but are not necessarily limited to such a structure and arrangement.

  FIG. 4 is a plan view showing an example of the pixel PE provided in the print area 21 as shown in FIG. As shown in FIG. 4, the pixel PE includes at least three subcells: a first subcell SC1, a second subcell SC2, and a third subcell SC3.

  In each subcell, the first subcell SC1 displays red under the condition of observing from an oblique direction intersecting with the normal of the main surface of the relief structure forming layer 22 (hereinafter simply referred to as the condition of observing from the oblique direction). The second subcell SC2 is a subcell that displays green, the third subcell SC3 is a subcell that indicates blue, and the colors displayed by the subcells have the same color intensity. It is arranged.

  Thereby, the observer can recognize that each pixel PE emits substantially white light under the condition of simply observing from an oblique direction.

  Further, the arrangement of the subcells is not limited to the arrangement shown in FIG. Furthermore, the area ratio of each subcell in the pixel PE can typically be equal to each other, but is not necessarily limited thereto.

  As described above, the first subcell SC1 is configured to display red. That is, the first subcell SC1 includes a plurality of concave portions or convex portions configured to emit diffracted light having a wavelength corresponding to red under the condition of observation from an oblique direction.

  The distance between the centers of such a plurality of concave portions or convex portions can be set within a range of 860 nm to 880 nm, for example.

  Further, the second subcell SC2 is configured to display green under the condition of observing from an oblique direction, and includes a plurality of concave portions or convex portions configured to emit diffracted light corresponding to green. Yes.

  The distance between the centers of the plurality of concave portions or convex portions for emitting the diffracted light corresponding to green can be set in the range of 755 nm to 775 nm, for example.

  Further, the third subcell SC3 is configured to display blue under the condition of observing from an oblique direction, and includes a plurality of concave portions or convex portions configured to emit diffracted light corresponding to blue. Yes.

  The distance between the centers of the plurality of concave portions or convex portions for emitting the diffracted light corresponding to blue can be set in the range of 735 nm to 755 nm, for example.

(First printing method)
FIG. 5 shows a first printing method for printing a color image on the color image printing medium 1 configured as described above.

  In the first printing method shown in FIG. 5, the laser beam 31 is irradiated from the marking layer 10 side of the color image printing medium 1.

  At this time, the laser beam 31 is irradiated to each subcell portion in each pixel PE provided in the printing area 21 while controlling the irradiation light amount or the irradiation area in accordance with desired image information to be printed. The

That is, each pixel PE before being irradiated with the laser light 31 is recognized as white light by an observer under the condition of observing from an oblique direction, while a specific pixel PE is changed to, for example, red. When it is desired to display, irradiation with the laser beam 31 is performed so that the first subcell SC1 in the target pixel PE is left and the entire surface of the second subcell SC2 and the third subcell SC3 are traced.

  As a result, the marking layer 10 at the position corresponding to the second subcell SC2 and the third subcell SC3 is colored, and the marking portion 11 is formed.

  Accordingly, when the observer observes the color image print medium 1 from the marking layer 10 side under the condition of observing from the oblique direction, the red color emitted from the first subcell SC1 is recognized, but emitted from the second subcell SC2. Green to be performed and blue to be emitted from the third subcell SC3 are shielded by the marking unit 11, and as a result, the target pixel PE is recognized as red.

  Similarly, in accordance with desired image information to be printed, each sub-cell in each pixel PE is irradiated with the laser beam 31 to obtain a desired color for each pixel PE under the condition of observing from an oblique direction. Can be injected.

  That is, each pixel PE does not necessarily emit only one of four colors of red, green, blue, and white, and as shown in the pixel PE of FIG. 6 according to the irradiation condition of the laser beam 31 to be irradiated. In addition, since the amount of light emitted from each subcell can be controlled by changing the area or density of the marking portion 21 for each subcell, the first subcell, the second subcell, and the third subcell result. It is possible to control the color for each pixel PE unit by additive color mixing of the emitted light.

  In particular, the marking portion 21 formed for each subcell for obtaining a color image is preferably formed as a print image based on the area gradation data.

  Further, by setting the marking layer 10 to have a black color at the time of color development, the ability to block the light emitted from each subcell is enhanced, and the light of each color emitted from each pixel PE can be recognized with high contrast. It becomes.

(Second printing method)
In the second printing method shown in FIG. 7, the laser light 31 is irradiated from the relief structure 20 side of the color image printing medium 1 by the laser light source 30.

  The laser beam 31 is irradiated from the relief structure 20 side, and the light reflection layer 23 provided in each subcell portion provided in each target pixel PE is removed based on desired image information to be printed. Then, the light reflection layer removal unit 26 is formed.

  Further, the marking portion 11 is formed on the marking layer 10 in synchronization with the position of the formed light reflection layer removal portion 26 by irradiation with the laser beam 31.

  Thereby, for example, when it is desired to display a specific pixel PE in blue, the third subcell SC3 in the target pixel PE is left as it is, and the light reflection layer 23 provided in the first subcell SC1; By removing the light reflection layer 23 provided in the second subcell SC2 and forming the light reflection layer removal portion 26, light emission from the subcell in which the light reflection layer removal portion 26 is formed is eliminated. Only the blue color emitted from the remaining third subcell SC3 can be viewed.

  It is desirable that the light reflection layer removing unit 26 and the marking unit 11 formed in each subcell are formed as a print image with area gradation.

  At the same time, the marking layer 10 at the position corresponding to the light reflection layer removing unit 26 is colored black so that the contrast can be increased.

  FIG. 8 is a plan view showing an example of the pixel PE printed in this way. An example in which the light reflection layer removing unit 26 and the marking unit 11 are formed in synchronization with the first subcell SC1 and the second subcell SC2 in the pixel PE based on the area gradation data is shown. .

  Further, by using such a second printing method, it is possible to visually recognize a similar color image even when the color image printing medium 1 is observed from either the front or back side.

  FIG. 9 is a cross-sectional view showing an example of an article provided with the color image printing medium 1.

  In FIG. 9, the marking layer 10 having the relief structure 20 provided on the surface opposite to the core sheet is provided on one side of the core sheet 41, and the relief structure 20 is provided on the surface opposite to the core sheet 41. The example which provided the marking layer 10 which is not provided and provided the oversheet as an outermost layer of both surfaces is shown.

  Although FIG. 9 shows an example of a configuration for producing a card as an article, it is not necessarily limited to this configuration.

  Also, the articles are not limited to cards, and can be used in any form such as various security labels, booklets such as passports, and threads inserted into paper substrates such as certificates.

Example 1
First, under the condition of observing from an oblique direction, the diffraction grating data that expresses white that is spread over the entire surface without gradation is designed for the pixel composed of each subcell that displays red, green, and blue, and is designed on the electron beam resist. Drawing was performed using an electron beam based on the diffraction grating data.

  This electron beam resist was developed to form a desired concave or convex portion. Then, after forming the nickel electrically conductive film by sputtering method, the metal mold | die was produced by nickel electroforming.

  Next, using a gravure coating method on a polyethylene terephthalate (PET) base material having a thickness of 19 μm, a UV curable resin that becomes a relief structure forming layer 22 and a release layer 24 made of an acrylic resin having a thickness of 1 μm are formed at a thickness of 1 μm. The raw material for forming was obtained by coating.

  A replica plate is made from the previously prepared nickel original plate to make a nickel practical plate, and the embossing with the nickel practical plate is applied to the forming raw material while applying heat of 100 ° C. and a pressure of 1 MPa, and UV light is applied. By irradiating, an embossed original fabric, that is, an original fabric having a relief structure forming layer 11 was obtained.

  Subsequently, aluminum was vapor-deposited with respect to this embossing raw material, and the 50-nm light reflection layer 23 was obtained.

  Thereafter, an adhesive made of an acrylic resin was applied to the aluminum deposition surface with a thickness of 2 μm by a gravure coating method. As described above, a relief structure 20 having a transfer foil configuration was obtained.

Using the relief structure 20 having the transfer foil structure thus obtained, transfer to a transfer target was performed. A white polycarbonate sheet having a thickness of 200 μm was used as the transfer target. In addition, the transfer was performed by pressing a 120 ° C. stamp at a pressure of 10 MPa, and after bonding to the white polycarbonate sheet, the substrate was peeled off to obtain a support made of the white polycarbonate sheet provided with the relief structure 20.

  Next, a transparent polycarbonate sheet having a thickness of 200 μm, a white polycarbonate sheet having a thickness of 200 μm, and a white polycarbonate sheet having the relief structure 20 are arranged on the relief structure 20 from the bottom, and the marking layer 10 and A 100 μm-thick laser coloring polycarbonate sheet and a 100 μm-thick transparent polycarbonate sheet were laminated in this order and laminated under the conditions of 195 ° C. and 1 MPa.

  The laminated sheet was punched into a card mold to obtain a card.

(Example 2)
A relief structure 20 having a transfer foil structure was produced in the same manner as in Example 1, and transferred to a 100 μm-thick laser-colored polycarbonate sheet to be the marking layer 10. For the transfer, the marking layer 10 (laser-colored polycarbonate sheet) provided with the relief structure 20 is peeled off after the base material is peeled off by pressing a 120 ° C. stamp at a pressure of 10 MPa to adhere to the laser-colored polycarbonate sheet as the marking layer 10. )

  Next, a transparent polycarbonate sheet having a thickness of 600 μm from the bottom and a marking layer 10 (laser-colored polycarbonate sheet) having the relief structure 20 are arranged with the relief structure 20 facing the upper surface, and a transparent polycarbonate having a thickness of 100 μm. Sheets were laminated in this order and laminated under the conditions of 195 ° C. and 1 MPa.

  The laminated sheet was punched into a card mold to obtain a card.

(Print evaluation)
Laser light was irradiated from the upper surface side of the card-like sample, that is, the side on which a transparent polycarbonate sheet having a thickness of 100 μm was laminated, and an image was printed by area gradation on each subcell in each pixel PE.

(Evaluation results)
In both Example 1 and Example 2, a good full-color image composed of a diffraction grating could be obtained. In Example 2, a full-color image could be visually recognized from either the front or back of the card.

  As described above, by using the color image printing medium of the present invention, a color image composed of a diffraction grating can be formed on demand, and the inner layer of the card structure as shown in the first and second embodiments. In this case, a full color image can be formed on demand. This makes it extremely difficult to tamper with the printed color image.

  As described above, color image information (personal authentication information) such as a face photograph can be printed on demand as a color image using a diffraction grating, and an article having an extremely high anti-counterfeit effect can be provided. it can.

DESCRIPTION OF SYMBOLS 1: Color image printing medium 10: Marking layer 11: Marking part 20: Relief structure 21: Print area 22: Relief structure formation layer 23: Light reflection layer 24: Release layer 25: Adhesion layer 26: Light reflection layer removal part 30 : Laser light source 31: Laser light 40: Card 41: Core sheet 42: Oversheet PE: Pixel SC1: First subcell (red)
SC2: Second subcell (green)
SC3: Third subcell (blue)

Claims (8)

A marking layer that is typically transparent in the visible light region and capable of laser printing, and at least a relief structure forming layer having a printing region having a plurality of pixels on at least a part of the marking layer are laminated. A color image printing medium,
Each of the plurality of pixels provided in the print area has at least three subcells,
The three subcells are configured to display a first subcell configured to display red under a condition of observing from an oblique direction intersecting with a normal line of the main surface of the relief structure forming layer, and to display green under the condition. The second subcell configured and the third subcell configured to display blue under the conditions, and arranged so that the three colors have the same color intensity under the observation conditions,
A color image printing medium, wherein a light reflection layer is provided so as to cover at least a part of a main surface of the relief structure forming layer and at least a part of the printing region.   The color image printing medium according to claim 1, wherein the light reflecting layer is made of a metal thin film.   The color image printing medium according to claim 1, wherein the marking layer contains at least polycarbonate.   An article comprising the color image printing medium according to any one of claims 1 to 3. A marking layer that is typically transparent in the visible light region and capable of laser printing, and at least a relief structure forming layer having a printing region having a plurality of pixels on at least a part of the marking layer are laminated. A color image printing medium,
Each of the plurality of pixels provided in the print area has at least three subcells,
The first subcell configured to display red under the condition that the three subcells are observed from an oblique direction intersecting with the normal line of the main surface of the relief structure forming layer, and to display green under the condition. The second subcell configured and the third subcell configured to display blue under the conditions, and arranged so that the three colors have the same color intensity under the observation conditions,
For a color image print medium provided with a light reflection layer so as to cover at least part of the main surface of the relief structure forming layer and at least part of the print region,
A printing method comprising a step of coloring a marking layer with a laser beam so as to block at least part of light to be emitted from a corresponding subcell according to a color image to be printed.   The printing method according to claim 5, wherein the color of the marking layer is black.   6. The method according to claim 5, further comprising: removing at least part of the light reflection layer provided in the corresponding subcell with a laser beam according to a color image to be printed to form a light reflection layer removal portion. Or the printing method of Claim 6. The printing method according to claim 7, wherein a position of the light reflection layer removing portion and a position of the marking layer that develops color by laser light are synchronized.