Laminate

Abstract

To provide a laminate capable of easily determining an authenticity when necessary without deteriorating design properties.SOLUTION: A laminate 1 includes a card base material 4, a hologram structure body 10 laminated thereon, a surface layer 3 formed with a transparent material and laminated upside thereof, and a printing layer 12 laminated upside thereof. The printing layer 12 includes a window part 13 being a print area with a transmission density of 0.15 to 0.75, inclusive, in an area overlapping the hologram structure body 10. The hologram structure body 10 includes: a reflection type hologram formation area recording a phase type Fourier-transform hologram, configured to transform light incident from a point light source into a desired optical image; and a vapor deposition layer having contact with a rugged surface. In the hologram formation area, phase information of a Fourier transformation image is multi-valued and recorded as a depth. The hologram formation area includes a plurality of aligned hologram cells each capable of transforming light incident from the point light source into an optical image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to laminates for which security is required, such as booklets, for example, credit cards, cash cards, ID cards, and passports. [Background technology]

[0002] Conventionally, booklets such as magnetic cards, IC cards, and passports with built-in IC tags have been used. The laminates constituting such cards and booklets need to take security measures such as preventing counterfeiting, and a representative method is to transfer a holographic foil onto the front and back surfaces of the laminate. Since holograms are difficult to counterfeit, the security of the laminate can be improved, but a method such as peeling the holographic foil from another laminate and replacing it was possible. Therefore, as described in Patent Document 1, a method of embedding the holographic foil inside the laminate, rather than on the front and back surfaces, has come to be used.

[0003] Although holograms have a strong function for determining authenticity, if they are always visible on the front and back surfaces of a laminate, the design and visibility of the laminate are restricted, and the location of the hologram is easily known, which makes it an easy target for counterfeiting. In response to this, Patent Document 2 proposes a hologram structure having a hologram layer having a reflective hologram formation area in which a phase-type Fourier transform hologram is recorded, which converts light incident from a point light source into a desired light image. This makes it possible to visually recognize the desired light image converted by the hologram only when a specific light is incident from a point light source. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2015-531705 [Patent Document 2] JP 2017-37272 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure has been made in consideration of these points, and aims to provide a laminate that allows easy authentication of authenticity when necessary without compromising design. [Means for solving the problem]

[0006] A first invention according to this embodiment is a laminate comprising a card substrate, a hologram structure laminated on a partial region of the card substrate, a surface layer formed of a transparent material laminated above the card substrate and the hologram structure, and a printed layer laminated on the upper side of the surface layer, wherein the printed layer has a window portion which is a printed region having a transmission density of 0.15 or more and 0.75 or less in at least a part of a region overlapping with the hologram structure when the surface of the laminate is viewed from the normal direction, and the hologram layer comprises a reflective hologram formation region in which a phase type Fourier transform hologram that converts light incident from a point light source into a desired optical image is recorded, and a deposition layer formed so as to be in contact with the uneven surface of the hologram formation region, wherein phase information of a Fourier transform image obtained by Fourier transform of an original image is multivalued and recorded as depth in the hologram formation region, and the hologram formation region is an array of hologram cells capable of converting light incident from a point light source into the optical image.

[0007] A second invention according to this embodiment is a laminate including a card substrate, a hologram structure laminated on a partial area on the card substrate, a surface layer formed of a transparent material laminated above the card substrate and the hologram structure, and a printed layer laminated on at least one of the upper and lower sides of the surface layer, when the direction from the card substrate toward the hologram structure is defined as the upper side and the opposite side is defined as the lower side, wherein the printed layer has a transmission density of 0.1 or less at least in a region overlapping with the hologram structure when the surface of the laminate is viewed from a normal direction. a window portion which is a printing area having a width of 0.5 or more and 0.75 or less, the hologram layer comprising: a reflective hologram forming area in which a phase type Fourier transform hologram is recorded that converts light incident from a point light source into a desired light image; and a vapor deposition layer formed so as to be in contact with the uneven surface of the hologram forming area, wherein phase information of a Fourier transform image obtained by Fourier transform of an original image is multivalued and recorded as depth in the hologram forming area, and the hologram forming area is an array of a plurality of hologram cells capable of converting light incident from a point light source into the light image.

[0008] A third invention according to this embodiment may be a laminate according to the first or second invention, wherein the planar size of the hologram formation region is within the range of 5 mm square to 50 mm square, the planar size of the hologram cell is 0.25 mm square or more, and the grating pitch of the uneven surface is within the range of 1.0 μm to 80.0 μm.

[0009] A fourth invention according to this embodiment is any one of the first to third inventions, wherein the printed layer is a laminate in which the transmission density of the window portion is 0.20 or more and 0.60 or less.

[0010] The fifth invention according to this embodiment may be a laminate in any one of the first to fourth inventions, in which a concealing layer is further provided between the surface layer and the printing layer, and when the surface of the laminate is viewed from the normal direction, the concealing layer is provided in an area excluding a portion of the window portion.

[0011] A sixth invention according to this embodiment may be the laminate of any of the first to fifth inventions, which is a card. Effect of the Invention

[0012] As described above, according to the present disclosure, it is possible to provide a laminate that allows easy authentication of authenticity when necessary without compromising design. [Brief description of the drawings]

[0013] [Figure 1] 1A and 1B are a plan view and a cross-sectional view illustrating a structure of a laminate according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view illustrating a laminate on which an optical image is displayed. [Diagram 3] 3A and 3B are a plan view and a cross-sectional view of a hologram structure. [Figure 4] 1A and 1B are explanatory diagrams illustrating a method for reconstructing an optical image using a hologram structure. [Diagram 5] 1A and 1B are explanatory diagrams illustrating a method for reconstructing an optical image using a hologram structure. [Figure 6] 1A and 1B are explanatory diagrams illustrating a method for reconstructing an optical image using a hologram structure. [Figure 7] FIG. 4 is an explanatory diagram illustrating a hologram formation region. [Figure 8] FIG. 4 is an explanatory diagram illustrating a hologram formation region. [Figure 9] FIG. 4 is an explanatory diagram illustrating a hologram formation region. [Figure 10] FIG. 13 is a diagram showing experimental results. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an example of the laminate of the present disclosure will be described with reference to the drawings, etc. However, the laminate of the present disclosure is not limited to the embodiments and examples described below.

[0015] The figures shown below are schematic. Therefore, the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, hatching showing the cross section of a member is appropriately omitted in each figure. The numerical values ​​such as dimensions of each member and the material names described in this specification are examples of embodiments, and are not limited thereto, and can be appropriately selected and used. In this specification, terms that specify shapes and geometric conditions, such as parallel, orthogonal, and vertical, are intended to include substantially the same state in addition to their strict meanings.

[0016] 1. Embodiments of the present disclosure An example of a typical embodiment of the laminate of the present disclosure will be described. FIG. 1(a) is a plan view illustrating the structure of the laminate according to this embodiment, and FIG. 1(b) is a cross-sectional view thereof. FIG. 1(b) is a cross-sectional view of the card 1 of FIG. 1(a) cut along a line AA parallel to the X-axis, viewed from the -Y direction. FIG. 2 is a plan view corresponding to FIG. 1(a), illustrating a laminate on which an optical image 230 is displayed. FIG. 3(a) is a plan view of a hologram structure 10 laminated inside the card 1, and FIG. 3(b) is a cross-sectional view thereof. FIG. 3(b) is a cross-sectional view of the hologram structure 10 of FIG. 3(a) cut along a line BB parallel to the X-axis, viewed from the -Y direction. In addition, FIGS. 4 to 6 are explanatory diagrams illustrating a method of reproducing an optical image using a hologram structure, and FIGS. 7 to 9 are explanatory diagrams illustrating a hologram formation region. In this embodiment, a card 1 having magnetic stripes 7 and 8 on the front and back sides will be described as an example of a laminate.

[0017] For ease of explanation, an XYZ coordinate system is set for card 1. First, as shown in Figures 1(a) and 1(b), the Z axis is taken as the normal direction to the main surface of card 1. Then, while looking at window 13 formed on the surface of card 1, the direction away from it is taken as the +Z direction or upward, and the opposite direction is taken as the -Z direction or downward.

[0018] When card 1 is viewed from the +Z direction, the X-axis is taken as a direction parallel to both short sides of card 1, and the direction from the long side furthest from magnetic stripe 7 to the long side closest to magnetic stripe 7 is taken as the +X direction or rightward direction, and the opposite direction is taken as the -X direction or leftward direction. Furthermore, the Y-axis is taken as a direction perpendicular to the X-axis and Z-axis, i.e., a direction parallel to both long sides of card 1, and the direction toward the top of the paper in Figure 1(a) is taken as the +Y direction, and the opposite direction is taken as the -Y direction.

[0019] When viewed in plan from the +Z direction, the card 1 has the form of a generally rectangular thin plate having two long sides and two short sides. Fig. 1(a) shows the card 1 arranged so that one short side is at the top end, and the other short side is omitted. When the card 1 is viewed in plan from the +Z direction, the first printed area 12a of the second printed layer 12 and the second printed area 12b of the second printed layer 12 arranged in the window portion 13 surrounded by the first printed area are visible on the outermost surface.

[0020] As described below, the window portion 13 is an area that allows the light image, when the light incident from a point light source is converted into a desired light image in the hologram structure 10, to be visually recognized through the second printed area 12b. The window portion 13 is an approximately square area in FIG. 1(a) and the like, but its shape and size are arbitrary. In addition, a predetermined pattern 20 (a pattern combining designs of circles, triangles, and squares in FIG. 1(a)) is formed in the window portion 13 by the printing ink that constitutes the second printed area 12b. Therefore, when the light incident from the point light source is converted into a desired light image in the hologram structure 10, the observer can visually recognize both the pattern 20 that constitutes the second printed area 12b and the light image superimposed thereon in the window portion 13.

[0021] As shown in FIG. 1(b), in the card 1, the oversheet layer 6, the core layer 5, the core layer 4, and the oversheet layer 3 are laminated from the -Z direction side to the +Z direction side to form the card base 2. In addition, the first printed layer 11 and the second printed layer 12 are further laminated by printing or the like on the +Z direction side of the oversheet layer 3 of the card base 2. In addition, magnetic stripes 7 and 8 are embedded in the +Z direction side surface of the oversheet layer 3 and the -Z direction side surface of the oversheet layer 6, respectively. Meanwhile, the hologram structure 10 is embedded in the boundary portion between the core layer 4 and the oversheet layer 3. The oversheet layer 3 is a surface layer formed of a transparent material laminated on the +Z direction side, i.e., the upper side, of the core layer 4 and the hologram structure 10. In addition, the printed layer including at least the second printed layer 12 is laminated on the upper side of the surface layer. Incidentally, the +Z direction from the card base material toward the hologram structure is defined as the upper side, and the opposite -Z direction is defined as the lower side. Furthermore, the printed layer including at least the second printed layer 12 may be laminated on at least one of the upper and lower sides of the surface layer. In other words, the printed layer including the second printed layer 12 may be disposed on the upper side of the surface layer, on the lower side, or on both the upper and lower sides. This is because the effect of the window portion formed by the second printed region 12b of the second printed layer 12 remains the same in any case.

[0022] When the surface of card 1 is viewed from the +Z direction side, a window portion 13 is formed by a second printed area 12b of a second printed layer having a predetermined printed area so as to overlap at least a part of hologram structure 10. Card 1 has an overall thickness of about 0.8 mm and complies with standards for credit cards and IC cards such as ISO / IEC7810 and ISO / IEC7816. The configuration of card 1 will be described in detail below.

[0023] (1) Card composition (a) Core layer The core layer is also called the card substrate. A wide variety of white or colored plastic sheets can be used as the core layers 4 and 5, and the following single films or composite films can be used. For example, polyethylene terephthalate (PET), PET-G (terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer), polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polycarbonate, polyamide, polyimide, cellulose diacetate, cellulose triacetate, polystyrene, ABS, polyacrylic acid ester, polypropylene, polyethylene, polyurethane, etc. The thickness of the core layers 4 and 5 can be appropriately selected taking into account the overall thickness of the card, and can be, for example, about 0.10 mm or more and 0.38 mm or less.

[0024] (b) Oversheet layer The over-sheet layer is also called a surface layer. The over-sheet layers 3 and 6 are made of the same material as the core layer, but a transparent material having a thickness of about 0.05 mm or more and 0.10 mm or less is often used. From the viewpoint of preventing curling when the laminate of the core layer and the over-sheet layer is integrated by heat pressing or the like, it is preferable that the over-sheet layers 3 and 6 have the same thickness, but they do not necessarily have to be the same. This point is also common to the above-mentioned core layers 4 and 5.

[0025] The material of the over-sheet layer may be any material that is adhesive when heated, but even if the over-sheet layer itself does not have adhesiveness when heated, the core layer and the over-sheet layer can be integrated by additionally forming a layer of a known adhesive that generates adhesive force when heated between them. In this embodiment, the magnetic stripes 7 and 8 are embedded in advance by thermal transfer or the like on the main surface side opposite the core layers 4 and 5 of both the over-sheet layers 3 and 6. In this way, the data on the magnetic stripe on both the front and back sides of the card 1 can be read by a magnetic reader or the like. However, it is not essential that the card 1 has a magnetic stripe on both the front and back sides, and the magnetic stripe may be embedded on only one of the front and back sides, or there may be no magnetic stripe on both the front and back sides.

[0026] (c) First printing layer The first printed layer 11 is provided to conceal the magnetic stripe 7 disposed on the lower layer side. Alternatively, the first printed layer 11 is provided to suppress the light image formed by the hologram structure 10 by the light incident from the point light source from being inadvertently viewed from an area other than the window portion 13. The first printed layer 11 may be, for example, a silver or gold printed layer called a concealing layer having glitter. The first printed layer 11, which is a concealing layer, is provided between the oversheet layer 3 and a second printed layer 12 described later. When the surface of the card 1 is viewed from the normal direction, the first printed layer 11 is provided in the area of ​​the oversheet layer 3 excluding a part of the window portion 13 described later, preferably in the area of ​​the oversheet layer 3 outside the outline of the window portion 13.

[0027] The first printed layer 11 is formed by forming a layer from aluminum metal powder or the like, which is metal particles with an average particle size of about 4 μm or more and 12 μm or less, into a paste form, dissolving this in a vehicle, i.e., a binder, to form an ink for silk screen printing, and then printing, applying, etc. Since the metal particles themselves are silver in color, the printed first printed layer 11 appears to be a shiny silver color.

[0028] As the binder for making the first printed layer 11 into ink, various resins can be used, such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, cellulose resin, acrylic resin, vinyl chloride-acrylate copolymer, bisphenol A type epoxy resin, etc. The first printed layer 11 can be formed relatively thick by performing silk screen printing using a predetermined screen mesh, for example, using an ink in which a metal resin is dissolved in a binder. The thickness of the first printed layer 11 can be set arbitrarily, but is usually about 1 μm or more and 5 μm or less, and preferably about 2 μm or more and 3 μm or less.

[0029] On the other hand, the first printed layer 11 may be made of a black ink having strong concealing properties other than the glittering ink, for the purpose of concealing the magnetic stripe 7 and suppressing the reflected light from the hologram structure 10. The black ink may be, for example, an ink containing carbon black.

[0030] The first printed layer 11 is disposed in an area that does not overlap at least a part of the window portion 13 when the surface of the card 1 is viewed from the +Z direction, and is preferably disposed in an area that does not overlap the entire window portion 13. The first printed layer 11 may be disposed in an area that does not overlap the hologram structure 10 when the surface of the card 1 is viewed from the +Z direction, or may be disposed in an area that overlaps with a part of the hologram structure 10, for example, a part of the outer periphery. In this embodiment, the window portion 13 is formed in an area that is slightly smaller than the contour of the hologram structure 10, and the first printed layer 11 is disposed so as to overlap each other to a position slightly inside the contour of the hologram structure 10. However, the window portion 13 is formed to a size that is approximately the same as or larger than the size of the hologram formation area 110 of the hologram structure 10, and is formed to include the hologram formation area 110 in a planar view.

[0031] With this configuration, when the surface of the card 1 is viewed from the +Z direction, only a necessary part of the light image, such as a specific pattern, can be seen through the window portion 13 of a limited size, rather than a light image due to the entire reflected light of the hologram structure 10. This prevents the design of the entire card from being impaired.

[0032] In the present disclosure, the first printed layer 11 is not essential, and in particular in a card without a magnetic stripe 7 or the like, only the second printed layer 12 may be formed on the upper layer side of the oversheet layer 3. The first printed layer 11 is printed in a single density, preferably a solid print with a transmission density of approximately 1.0, over the entire area in which it is formed. However, the first printed layer 11 may be formed to slightly overlap the outline of the window 13 of the second printed layer 12 and its inner area, and may be configured to have a gradation of transmission density from dark to light as it moves from the outside of the outline of the window 13 to the inner area. The gradation areas of the first printed layer 11 and the second printed layer 12 may be formed so that the gradation area of ​​the first printed layer 11 and the gradation area near the window 13 of the second printed layer 12 overlap each other.

[0033] With this configuration, when the surface of card 1 is viewed from the +Z direction, the observer can effectively view the light image reproduced by hologram structure 10 without the window portion 13 compromising the overall design of card 1.

[0034] (d) Second printing layer The second printed layer may be any color or design that includes an area that overlaps with the hologram structure 10 when the surface of the laminated card 1 is viewed from the normal direction. The ink that constitutes the second printed layer contains a colorant and a resin material.

[0035] The coloring material of the ink used in the second printing layer 12 may be a color pigment such as an inorganic pigment or an organic pigment. As inorganic pigments, for example, yellow lead and zinc yellow are used as yellow pigments, iron oxide red and red lead are used as red pigments, and ultramarine blue and potassium iron ferrocyanide are used as blue pigments. Examples of organic pigments include isoindolinone, isoindoline, azomethine, anthraquinone, anthrone, and xanthene as yellow pigments, quinacridone, diketopyrrolopyrrole, anthraquinone, perylene, perinone, and indigoid as red pigments, and polycyclic pigments such as phthalocyanine, anthraquinone, and indigoid as blue pigments. In addition, monoazo compounds, diazo compounds, and triazo compounds are used as azo pigments.

[0036] Further, examples of the coloring material used in the second printed layer 12 include dyes other than the above-mentioned color pigments, such as acid dyes, direct dyes, disperse dyes, oil-soluble dyes, metal-containing oil-soluble dyes, and sublimation dyes. Furthermore, fluorescent light-emitting materials such as ultraviolet light-emitting materials and infrared light-emitting materials that emit fluorescence by absorbing ultraviolet or infrared light, polarized cholesteric polymer liquid crystal pigments, and particles that act as reflective mirrors, such as glass beads, may also be used as the coloring material.

[0037] On the other hand, as the binder for making the second printed layer 12 into ink, various resins can be used, such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, cellulose resin, acrylic resin, vinyl chloride-acrylate copolymer, bisphenol A type epoxy resin, etc. By forming a printed layer with a predetermined dot configuration by, for example, offset printing using ink in which the above-mentioned pigment is dissolved in a binder, it is possible to form the window portion 13, which is a printed area with a predetermined transmission density in at least a part of the area overlapping with the hologram structure 10.

[0038] The second printed layer 12 does not need to be a printed area with a constant transmission density throughout its entirety, and it is sufficient that the second printed area 12b, which is at least a part of the area overlapping with the hologram structure 10, has a predetermined transmission density. The second printed layer 12 may have any transmission density in the first printed area 12a, which is the area other than the part. The transmission density of the second printed area 12b is preferably 0.15 to 0.75, and more preferably 0.20 to 0.60, but this will be described later. The transmission density is the transmission density defined in JIS X6305-1 (2010) measured using a visual filter mode of a Macbeth model TD904.

[0039] The second printed layer 12 may be configured such that the transmission density changes continuously or stepwise from dark to light from the first printed region 12a, which is a region other than the second printed region 12b, which is at least a part of the region overlapping with the hologram structure 10, toward the second printed region 12b. In other words, the second printed layer 12 may be configured such that the transmission density has a gradation from dark to light from the first printed region 12a, which is outside the contour of the window portion 13, toward the second printed region 12b, which is inside the contour of the window portion 13. In this way, when the surface of the card 1 is viewed from the +Z direction, the optical image reproduced by the hologram structure 10 can be effectively viewed without the window portion 13 impairing the overall design of the card 1.

[0040] The method of forming the second printed layer 12, i.e., the printing method, can be the same as the method of forming a general printed layer. Specific examples of the printing method include various printing methods such as inkjet printing, screen printing, offset printing, gravure printing, and flexographic printing. In addition, the ink used for the printed layer can be one used for forming a general printed layer, and the resin material and colorant dispersed or dissolved in a solvent can be used.

[0041] (e) Hologram structure 3(b), the hologram structure 10 has a configuration in which a deposition layer 170, a hologram layer 160, an interlayer adhesive layer 150, and a transparent substrate 140 are laminated from the -Z direction side to the +Z direction side. The hologram layer 160 has a hologram formation region 110 of a reflection type hologram in which a phase type Fourier transform hologram is recorded, which converts light incident from a point light source into a desired optical image.

[0042] The deposition layer 170 is formed on the surface of the hologram layer 160 on the -Z direction side so as to be in contact with the uneven surface 130 of the hologram formation region 110, and typically the size of the hologram formation region 110 in a plan view is 5 mm square or more. For ease of explanation, the transparent base material 140 and the interlayer adhesive layer 150 are omitted from FIG. 3(a). In addition, in FIG. 3(a), the region surrounded by the dashed line is the hologram formation region 110. Details of the hologram structure 10 are as follows.

[0043] (i) Holographic layer The hologram layer 160 has a reflection type hologram forming region in which a phase type Fourier transform hologram that converts light incident from a point light source into a desired optical image is recorded. Here, the recording of a phase type Fourier transform hologram means that the phase information of a Fourier transform image obtained through a Fourier transform of an original image is multi-valued and recorded as depth, and an uneven surface 130 is formed in the hologram forming region 110 of the hologram layer 160 in which the phase type Fourier transform hologram is recorded.

[0044] The hologram layer 160 converts light incident from a point light source into a desired optical image by using the height difference of the uneven shape constituting the uneven surface 130 of the hologram formation area 110. In other words, the hologram layer 160 functions as a Fourier transform lens. With this function, light incident from an arbitrary point light source is diffracted in a number of predetermined directions to form a predetermined image as an optical image. This function is sometimes called the "Fourier transform lens function."

[0045] Hologram formation region 110 is of a reflective type, and when a point light source is disposed on the observation surface side and hologram layer 160 is viewed in plan from the observation surface side, an optical image can be reproduced in hologram formation region 110. Hologram formation region 110 indicates an area in which light incident from a point light source can be converted into a desired optical image, and specifically, is an area surrounded by a rectangle of the minimum area that can include all hologram cells that can be converted into the above-mentioned optical image.

[0046] In the present disclosure, the planar size of hologram formation area 110 being 5 mm square or more means that the above hologram formation area 110 has a shape in planar view that includes at least the area of ​​a 5 mm square. Therefore, when hologram formation area 110 is rectangular, this means that the length of its short side is 5 mm or more, and when hologram formation area 110 is square, this means that the length of one side is 5 mm or more.

[0047] In the present disclosure, the planar size is preferably in the range of 5 mm square or more and 50 mm square or less, more preferably in the range of 5 mm square or more and 30 mm square or less, and particularly preferably in the range of 5 mm square or more and 15 mm square or less. When the lower limit of the planar size is within the above range, the hologram structure 10 makes it easy to visually recognize the optical image inside the hologram formation region 110. As a result, it can be made to have excellent anti-counterfeiting properties and design properties. In addition, when the upper limit of the planar size is within the above range, the hologram structure 10 can be manufactured at low cost.

[0048] As described above, when the size of hologram formation area 110 in a plan view is a predetermined size, it is preferable that window portion 13 is formed at a position and with a size that includes hologram formation area 110 in a plan view of window portion 13. In other words, it is preferable that window portion 13 is formed so as to include the entirety of hologram formation area 110 in a plan view of window portion 13. This allows the viewer to reliably view the optical image formed in hologram formation area 110 without interruption, and window portion 13 can be formed in the minimum area required for viewing the optical image, thereby minimizing window portion 13 and improving the design of card 1.

[0049] As illustrated in Fig. 4(a), consider a case in which the planar size of hologram formation region 110 in hologram structure 10 is small and light source 220 is located far from hologram structure 10. In this case, observer 210 may be able to view only a portion of the entire image of light image 240 (the letter "E"), as illustrated in Fig. 4(b).

[0050] 5(a), in order to make the entire image of light image 240 visible in hologram formation region 110, which has a small planar size, it is necessary to place light source 220 close to hologram structure 10. In this case, as shown in FIG. 5(b), the size of reconstructed light image 240 (letter "E") is small, and observer 210 may have difficulty visually recognizing the information displayed by light image 240.

[0051] In contrast, as shown in Fig. 6(a), the planar size of hologram formation region 110 is assumed to be 5 mm square or more. In this case, even if light source 220 is moved away from hologram structure 10, observer 210 can visually recognize the entire image of light image 240 (letter "E") in hologram formation region 110, as shown in Fig. 6(b). Also, observer 210 can easily visually recognize information displayed by reconstructed light image 240.

[0052] 7 to 9 are explanatory diagrams for explaining the hologram formation region. In the present disclosure, the hologram formation region 110 may be, as shown in Fig. 7(a), a hologram formation region 110 composed of one hologram cell 110a in which a phase-type Fourier transform hologram that converts light incident from a point light source into a desired optical image is recorded.

[0053] However, normally, hologram formation area 110 is an expanded hologram formation area 110 obtained by arranging a plurality of hologram cells 110a as shown in Fig. 7(b). Note that hologram cells 110a may be simply referred to as hologram cells, and hologram formation area 110 may be simply referred to as a single hologram area. Hologram formation area 110 as shown in Fig. 7(b) may be referred to as a large-sized hologram area.

[0054] When the hologram formation region 110 is a large-sized hologram region, the planar size of each hologram cell 110a constituting the hologram formation region 110 may be any size that allows the hologram formation region 110 to be formed with high accuracy. The planar size is preferably within a range of 0.25 mm square or more and 5 mm square or less. When the planar size is within the above range, the hologram structure 10 can easily reproduce an optical image inside the hologram formation region 110. The planar size refers to the size of the smallest square that can include the hologram cell 110a. When the hologram cell 110a is a square with one side of 1 mm, the planar size is 1 mm square, and when the planar shape of the hologram cell 110a is a circle with a diameter of 1 mm, the planar size is 1 mm square.

[0055] The ratio of the area of ​​the hologram cells 110a in the hologram formation region 110 in a plan view is not particularly limited as long as the desired optical image can be reproduced, but is preferably 25% or more, and more preferably 50% or more. When the area ratio is within the above range, the hologram structure 10 can reproduce the optical image 240 clearly.

[0056] The planar shape of the hologram cell 110a may be any shape as long as it is possible to form a desired planar shape of the hologram formation region 110. Specifically, the planar shape may be a square, rectangular, trapezoidal, triangular, polygonal, circular, elliptical, star-shaped, heart-shaped, etc., but is usually rectangular from the viewpoint of ease of forming the hologram formation region.

[0057] In the present disclosure, the uneven shape of uneven surface 130 of hologram formation region 110 corresponds to a pattern of Fourier transform images when a plurality of multi-valued Fourier transform images formed based on image data of an original picture to be displayed as an optical image are arranged in a desired range in the vertical and horizontal directions. Any method can be used to form such uneven surface 130 in hologram formation region 110 as long as it is capable of forming uneven surface 130 capable of converting light incident from a point light source into a desired optical image, and a general method for forming a Fourier transform hologram can be used.

[0058] Specifically, the above-mentioned forming method can be a method of forming a master plate having a concave-convex pattern corresponding to a Fourier transform image, and transferring the concave-convex pattern of the master plate to a coating film of a resin material such as an ultraviolet curable resin formed on a substrate such as PET, thereby forming the concave-convex surface 130 of the hologram formation region 110. In addition, by transferring the concave-convex pattern of the master plate only once, a single hologram region consisting of one hologram cell 110a can be formed as the hologram formation region 110. In addition, by transferring the concave-convex pattern of the master plate multiple times, a hologram layer having a large-sized hologram formation region of a desired size in which multiple hologram cells 110a are arranged can be formed as the hologram formation region 110.

[0059] The method of forming the master plate is to form a Fourier transform image by calculation based on the image data of the original image to be displayed. Next, the data of the Fourier transform image is converted into binary or more multi-value data and converted into electron beam lithography data, and the electron beam lithography data is arranged to a desired range. For example, 10 pieces of electron beam lithography data are arranged vertically and horizontally. Next, a method is used in which a master plate is created using an electron beam lithography device based on the arranged electron beam lithography data. When the data after the Fourier transform is binarized as the electron beam lithography data, the uneven shape of the uneven surface 130 is a two-stage uneven shape as shown in FIG. 8(a), and when the data is four-value data, the uneven shape is a four-stage uneven shape as shown in FIG. 8(b).

[0060] In the present disclosure, it is preferable that the data of the Fourier transform image is multi-valued to four or more values, that is, the uneven shape is an uneven shape having four or more steps, because this makes it possible to reproduce an optical image with a complex shape.

[0061] The grating pitch of the uneven surface 130 may be any pitch that can convert light incident from a point light source into a desired optical image. Specifically, the grating pitch is preferably in the range of 1.0 μm or more and 80.0 μm or less. When the grating pitch is in the above range, the hologram structure 10 can easily reproduce an optical image inside the hologram formation region 110. The grating pitch refers to, for example, the width indicated by P in FIG. 8(a) and FIG. 8(b).

[0062] 9, when light source 220 is disposed at a position at a predetermined distance L1 from hologram formation region 110 of hologram structure 10 and observer 210 is positioned at a position at a predetermined distance L2 from hologram formation region 110, the following formula (1) can be established for the grating pitch so that observer 210 can observe the entire light image in the entire region of hologram formation region 110. Note that λ is the wavelength of the diffracted light, P is the grating pitch of uneven surface 130, θ1 is the angle of incidence for light source 220 to reach the end of hologram formation region 110, θ2 is the diffraction angle for the diffracted light from the end of hologram formation region 110 to reach observer 210, and n is the order of diffraction. P = nλ / (sinθ1 + sinθ2) (1)

[0063] As a specific calculation example of the grating pitch, when hologram formation area 110 is a square with one side measuring 15 mm, L1 is 50 mm, L2 is 300 mm, and the light has a wavelength of 550 nm, sin θ2=0.025 and sin θ1=0.148 are calculated, and the grating pitch P required for observer 210 to observe the entire light image in the entire area of ​​hologram formation area 110 is calculated to be 3,179 nm at the shortest. When hologram formation area 110 is a square with one side measuring 15 mm, L1 is 1,990 mm, L2 is 2,000 mm, and the light has a wavelength of 550 nm, sin θ2=0.00374 and sin θ1=0.00377 are calculated, and the grating pitch P is calculated to be 73,236 nm at the shortest.

[0064] Furthermore, if the hologram formation area 110 is a square with sides of 10 mm, L1 is 60 mm, L2 is 60 mm, and the light has a wavelength of 550 nm, sinθ2=0.083 and sinθ1=0.083 are calculated, and the grating pitch P is calculated to be 3,313 nm at the shortest. The depth of the uneven shape can be about 0.01 μm. The depth is, for example, that shown by D in FIG. 8(a) and FIG. 8(b).

[0065] In the hologram formation region 110, the wavelength of the point light source capable of realizing the above-mentioned Fourier transform lens function is not particularly limited, and any desired wavelength can be targeted. In addition, the wavelength of the point light source is not limited to monochromatic light of one wavelength, but may be light including multiple wavelengths, or may even be white light.

[0066] The material constituting the hologram layer 160 is not particularly limited as long as it can form a concave-convex shape for realizing the above-mentioned Fourier transform lens function in the hologram formation region 110 and has a predetermined refractive index. The refractive index of the material constituting the hologram layer 160 is not particularly limited, and can be appropriately set according to the application of the hologram structure 10 of the present disclosure. The wavelength serving as the reference for the refractive index is also not particularly limited, and may be appropriately selected from the range of 400 nm or more and 750 nm or less. In particular, in the present disclosure, the refractive index at a wavelength of 555 nm is preferably in the range of 1.3 or more and 2.0 or less, and particularly preferably in the range of 1.33 or more and 1.8 or less. Here, the refractive index can be measured by a spectroscopic ellipsometer.

[0067] As the material of the hologram layer 160, resin materials conventionally used for forming relief-type holograms, for example, cured products of curable resins such as thermosetting resins, ultraviolet curing resins, and ionizing radiation curing resins, and thermoplastic resins can be used. As the thermosetting resins, for example, unsaturated polyester resins, acrylic-modified urethane resins, epoxy-modified acrylic resins, epoxy-modified unsaturated polyester resins, alkyd resins, and phenolic resins can be used. As the thermoplastic resins, for example, acrylic ester resins, acrylamide resins, nitrocellulose resins, and polystyrene resins can be used. These resins may be homopolymers or copolymers consisting of two or more kinds of constituent components. These resins may be used alone or in combination of two or more kinds.

[0068] The above-mentioned thermosetting resin or thermoplastic resin may contain a heat or ultraviolet curing agent such as various isocyanate compounds, metal soaps such as cobalt naphthenate and zinc naphthenate, organic peroxides such as benzoyl peroxide and methyl ethyl ketone peroxide, benzophenone, acetophenone, anthraquinone, naphthoquinone, azobisisobutyronitrile, and diphenyl sulfide.

[0069] Examples of the ionizing radiation curable resin include epoxy-modified acrylate resins, urethane-modified acrylate resins, and acrylic-modified polyester resins. Among these, urethane-modified acrylate resins are preferred, and urethane-modified acrylic resins represented by the chemical formula shown in JP-A-2007-017643 are particularly preferred.

[0070] When the ionizing radiation curable resin is cured, monofunctional or polyfunctional monomers, oligomers, etc. can be used in combination for the purpose of adjusting the crosslinking structure, viscosity, etc. Examples of the monofunctional monomer include mono(meth)acrylates such as tetrahydrofurfuryl(meth)acrylate, hydroxyethyl(meth)acrylate, vinylpyrrolidone, (meth)acryloyloxyethyl succinate, and (meth)acryloyloxyethyl phthalate. In addition, examples of monomers having two or more functional groups, when classified by skeleton structure, include polyol(meth)acrylates (e.g., epoxy-modified polyol(meth)acrylate, lactone-modified polyol(meth)acrylate, etc.), polyester(meth)acrylate, epoxy(meth)acrylate, urethane(meth)acrylate, and other poly(meth)acrylates having skeletons such as polybutadiene-based, isocyanuric acid-based, hydantoin-based, melamine-based, phosphoric acid-based, imide-based, and phosphazene-based, etc. In addition, various monomers, oligomers, and polymers that are UV-curable or electron beam-curable can be used.

[0071] More specifically, examples of bifunctional monomers and oligomers include polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. Examples of trifunctional monomers, oligomers, and polymers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and aliphatic tri(meth)acrylate. Examples of tetrafunctional monomers and oligomers include pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and aliphatic tetra(meth)acrylate. Examples of pentafunctional or higher monomers and oligomers include dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like. Examples of (meth)acrylates having a polyester skeleton, a urethane skeleton, or a phosphazene skeleton are also included. The number of functional groups is not particularly limited, but if the number of functional groups is less than 3, heat resistance tends to decrease, and if it exceeds 20, flexibility tends to decrease. Therefore, it is particularly preferable that the number of functional groups is in the range of 3 to 20.

[0072] The content of the monofunctional or polyfunctional monomer or oligomer as described above can be appropriately adjusted, but in general, it is preferably 50 parts by weight or less per 100 parts by weight of the ionizing radiation curable resin, and more preferably within the range of 0.5 parts by weight or more and 20 parts by weight or less.

[0073] In addition, the hologram layer 160 may contain additives such as photopolymerization initiators, polymerization inhibitors, deterioration inhibitors, plasticizers, lubricants, colorants such as dyes and pigments, surfactants, defoamers, leveling agents, and thixotropy-imparting agents, as necessary.

[0074] The thickness of the hologram layer 160 is preferably in the range of 0.05 mm to 5 mm, and more preferably in the range of 0.1 mm to 3 mm, when the hologram layer is self-supporting. On the other hand, when the hologram layer 160 is not self-supporting and is formed on a transparent substrate described later, the thickness of the hologram layer 160 is preferably in the range of 0.1 μm to 50 μm, and more preferably in the range of 2 μm to 20 μm. The thickness of the hologram layer is specifically the distance indicated by a in FIG. 3(b) already described. The size of the hologram layer 160 in plan view can be appropriately set according to the application of the hologram structure 10 of the present disclosure.

[0075] The hologram layer 160 in the present disclosure has at least the hologram formation region 110, but may have a region where no uneven shape is formed (non-hologram formation region) in addition to the hologram formation region 110. The proportion of each of the above regions in the hologram layer 160 is not particularly limited and can be appropriately selected depending on the application.

[0076] (ii) Vapor deposited layer The deposition layer 170 in the present disclosure is formed so as to be in contact with the uneven surface 130 of the hologram formation region 110 of the hologram layer 160. The deposition layer 170 may be transparent or reflective. When the deposition layer 170 is a transparent deposition layer having transparency, the hologram formation region 110 of the hologram structure 10 does not have gloss when viewed in a plan view. Therefore, in such a hologram structure 10, the hologram formation region 110 is concealed, and the hologram structure 10 has excellent anti-counterfeiting properties and design properties.

[0077] On the other hand, when the deposition layer 170 is a reflective deposition layer having reflectivity, the hologram structure 10 can clearly reproduce an optical image in the hologram formation region 110. Therefore, the hologram structure 10 has excellent anti-counterfeiting properties and design properties.

[0078] The transparent vapor deposition layer preferably has a total light transmittance (hereinafter sometimes simply referred to as light transmittance) of 80% or more, and more preferably 90% or more. This is because the above light transmittance allows the hologram formation area 110 of the hologram structure 10 to be more concealed. The above light transmittance is a value measured according to JIS K7361-1 (Test method for total light transmittance of plastic-transparent materials).

[0079] The material constituting the deposition layer 170 is not particularly limited as long as it is a material that generates a refractive index difference between the deposition layer 170 and the hologram layer 160. Examples of materials capable of forming the reflective deposition layer include metals such as Mg, Al, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Se, Rb, Pd, Ag, Cd, In, Sn, Sb, Te, Au, Pb, and Bi. Examples of materials capable of forming the transparent deposition layer include oxides of the above metals, and the above materials can be used alone or in combination of two or more materials.

[0080] The thickness of the deposition layer 170 can be appropriately set in view of the desired reflectivity, color tone, design, use, etc., and is preferably within the range of 50 Å to 1 μm, and more preferably within the range of 100 Å to 1,000 Å. From the viewpoint of imparting transparency to the deposition layer, the thickness is preferably 200 Å or less, and from the viewpoint of imparting hiding power to the deposition layer, the thickness is preferably greater than 200 Å. The thickness of the deposition layer 170 is specifically the distance indicated by b in FIG. 3(b) already described.

[0081] The deposition layer 170 may be formed at a location that overlaps at least all of the uneven surface 130 in the hologram formation region 110 in a planar view, and may cover the entire surface of the hologram layer 160 on the uneven surface 130 side. The deposition layer 170 may be formed by any general deposition layer forming method, such as vacuum deposition, sputtering, or ion plating.

[0082] (iii) Transparent base material The hologram structure 10 of the present disclosure may have a transparent substrate 140 formed on the surface of the hologram layer 160 opposite to the deposition layer 170. By having the transparent substrate 140, the thermal or mechanical strength of the hologram structure 10 can be increased. The transparent substrate 140 may be formed so as to be in direct contact with the hologram layer 160, or may be formed via another layer. For example, the transparent substrate 140 may be bonded to the surface of the hologram layer 160 via an interlayer adhesive layer 150 described later.

[0083] The light transmittance of the transparent substrate 140 is preferably 80% or more, and more preferably 90% or more. By setting the light transmittance of the transparent substrate 140 within the above-mentioned range, the hologram structure 10 allows easy visual recognition of the optical image. In addition, the lower the haze value of the transparent substrate 140, the more preferable it is, and specifically, the haze value is preferably within the range of 0.01% or more and 5% or less, and more preferably within the range of 0.01% or more and 3% or less, and particularly preferably within the range of 0.01% or more and 1.5% or less. This is because by setting the haze value of the transparent substrate within the above-mentioned range, it is possible to display the optical image that appears in the hologram formation region without impairing the visibility. The haze value of the transparent substrate is a value measured in accordance with JISK7136.

[0084] The material constituting the transparent substrate 140 is not particularly limited as long as it exhibits the above-mentioned light transmittance and haze value, and examples of materials that can be used include resin films such as polyethylene terephthalate, polycarbonate, acrylic resin, cycloolefin resin, polyester resin, polystyrene resin, and acrylic styrene resin, and glass such as quartz glass, Pyrex (registered trademark), and synthetic quartz plate. Of these, it is preferable to use a resin film as the transparent substrate 140 because it is lightweight and has little risk of breakage, and polycarbonate is optimal in terms of birefringence.

[0085] If necessary, additives may be included in the transparent substrate 140. Examples of the additives include dispersants, fillers, plasticizers, and antistatic agents.

[0086] The transparent substrate 140 may have a thickness that is sufficient to provide the rigidity and strength required to support the hologram layer 160 and the like, and is preferably, for example, about 0.005 mm or more and 5 mm or less, and more preferably, is within a range of 0.02 mm or more and 1 mm or less. The shape of the transparent substrate 140 is not particularly limited, and can be appropriately selected depending on the mode of use of the hologram structure 10 of the present disclosure. The transparent substrate 140 may have a surface that has been subjected to, for example, corona treatment, etc., in order to improve adhesion to other layers.

[0087] (iv) Interlayer adhesive layer The hologram structure 10 of the present disclosure may have an interlayer adhesive layer 150 that bonds the respective components. The interlayer adhesive layer 150 may be one that is generally used for the hologram structure 10, and is appropriately selected depending on the materials constituting the transparent substrate 140 and the hologram layer 160. As the interlayer adhesive layer 150, for example, a known adhesive layer such as a two-liquid curing adhesive layer, an ultraviolet curing adhesive layer, a heat curing adhesive layer, or a hot melt adhesive layer may be used. The thickness of the interlayer adhesive layer 150 is appropriately set depending on the size of the components to be bonded, etc.

[0088] (2) Manufacturing method of the card according to this embodiment Next, a method for manufacturing the card 1 of this embodiment will be briefly described.

[0089] (a) Formation of master and hologram structure A photomask blank plate, which is a synthetic quartz substrate with a low-reflection chrome thin film laminated thereon, is spin-coated with a dry etching resist by a spinner onto the chrome thin film to form a resist layer of a specified thickness. Next, a computer-generated pattern is exposed to this resist layer using an electron beam lithography device, and the exposed portions of the resist resin are made soluble. After that, a developer is sprayed (spray development) to remove the soluble portions, forming a resist pattern.

[0090] Next, using the formed resist pattern, the chromium thin film in the portion not covered with the resist is etched away by dry etching to expose the quartz substrate, and the exposed quartz substrate is etched to form recesses in the quartz substrate. Thereafter, the resist thin film is dissolved and removed to obtain a master having recesses formed by etching the quartz substrate and protrusions in which the quartz substrate and the chromium thin film remain unetched.

[0091] A composition for forming a hologram layer 160 is dropped onto a transparent substrate 140 of a predetermined thickness to form a coating of the composition. Next, an original plate having projections and recesses is placed on the coating, pressed, and irradiated with active radiation to harden the coating, and then peeled off. As a result, a hologram cell having a projection and recess surface 130 that is the inverse of the projection and recess pattern of the original plate is formed. Thereafter, the original plate is repeatedly placed, pressed, hardened, and peeled off to form a hologram layer 160 having a hologram formation region 110 of a predetermined square dimension in which hologram cells are laid out.

[0092] Next, an Al layer having a predetermined thickness is formed by sputtering over the entire surface of the hologram layer 160 on the side of the uneven surface 130, thereby obtaining the hologram structure 10.

[0093] (b) Card Creation Next, as components of the large-format card base 2 with multiple card faces attached, core layers 4 and 5 of predetermined thickness and transparent oversheets 3 and 6 of predetermined thickness onto which magnetic stripes 7 and 8 have been thermally transferred are prepared. The above-mentioned hologram structure 10 is temporarily attached to one surface of the core 4, and the oversheet layer 6, core layer 5, core layer 4, and oversheet layer 3 are laminated from the -Z direction side to the +Z direction side, as shown in Figure 1(b).

[0094] Here, as described above, the hologram structure 10 is embedded in advance in the boundary portion between the core layer 4 and the oversheet layer 3. In this state, stainless steel plates are applied to the laminated large-sized card base 2 from the +Z direction side and the -Z direction side, respectively, and a predetermined heat and pressure are applied for a predetermined time using a heat press machine, thereby obtaining a large-sized card base 2 in which each layer is heat-fused.

[0095] Meanwhile, a release varnish is applied to the PET film by silk printing or the like, a second printed layer 12 is applied by offset printing or the like, and a first printed layer 11 is applied by silk printing or the like in this order. The second printed layer 12 also forms a window portion 13. The PET film thus printed is placed on the surface of the oversheet 3 of the large-sized card base 2 in which the layers have been heat-sealed as described above, with the printed layer facing the oversheet 3.

[0096] After that, stainless steel plates are again applied to the laminated large-sized card base 2 from the +Z direction side and the -Z direction side, respectively, and a predetermined heat and pressure is applied for a predetermined time using a heat press machine. As a result, each printed layer is transferred from the PET film to the large-sized card base 2 side. This is then punched out to card size using a punching machine to obtain card 1.

[0097] Here, the surface of card 1 may be a matte surface, that is, a surface that has been matte-finished. Matte-finishing refers to processing that makes the surface of card 1 a matte surface, that is, a surface with irregularities. For example, the matte-finishing may be performed by blowing fine sand onto a plastic film using sandblasting, or by forming the irregularities of a stainless steel plate used for pressing onto a plastic film.

[0098] The first printed layer 11, which can be formed by silk printing or the like, functions as an adhesive between the surface of the oversheet 3 and the underside of the second printed layer 12. When the surface of the oversheet 3 is a matte surface, the adhesive area of ​​that surface increases, thereby improving the adhesive performance of the first printed layer 11.

[0099] (3) Functions and Effects of the Card of the Present Invention Next, the action and effect of the card 1 of this embodiment having the above-mentioned configuration will be described. The card 1 has a hologram structure 10 embedded inside the card base 2. The hologram structure 10 has a hologram layer 160 having a reflective hologram formation area 110 in which a phase-type Fourier transform hologram is recorded, which converts light incident from a point light source into a desired optical image. The hologram structure 10 is capable of reproducing an optical image in the hologram formation area 110 when the hologram layer 160 is viewed in plan from the observation surface side by arranging a point light source on the opposite side to the uneven surface 130 of the hologram layer 160 (hereinafter, sometimes referred to as the observation surface side).

[0100] A second printed layer 12 is provided on card 1, and second printed layer 12 has a window portion 13 which is a printed area in which at least a part of the area overlapping with hologram structure 10 has a transmission density of 0.15 or more and 0.75 or less when the surface of card 1 is viewed from the normal direction. Here, if a point light source is not arranged on the surface of card 1 on the observer side, when an observer views window portion 13 on the surface of card 1 from the normal direction, the observer can only see a predetermined pattern 20 formed by second printed layer 12 arranged in window portion 13, as shown in FIG. 1(a).

[0101] On the other hand, when a predetermined point light source is arranged on the front surface of card 1 on the observer side, when the observer looks at window portion 13 on the front surface of card 1 from the normal direction, the observer can visually recognize the pattern of light image 230 reproduced in hologram formation region 110 of hologram structure 10, in addition to the predetermined pattern 20 formed by second printed layer 12 arranged in window portion 13, as shown in Fig. 2. In other words, the observer can visually recognize, in window portion 13, the predetermined pattern 20 formed by second printed layer 12 and the pattern of light image 230 at least partially superimposed thereon.

[0102] For this reason, in the card 1 of this embodiment, authenticity can be easily determined and design properties can be realized simply by arranging a specific point light source on the observer side, without the need to prepare a separate screen for projecting a light image, etc. Also, since the card 1 of this embodiment can reproduce a light image only when it is irradiated with light from the specific point light source, it is usually not recognized that the card 1 has a built-in hologram, and the card can have excellent anti-counterfeiting properties and design properties.

[0103] Here, window portion 13 formed in second printed layer 12 of card 1 of this embodiment has a printed area in which the transmission density of at least a part of the area overlapping with hologram structure 10 is 0.15 or more and 0.75 or less when the surface of card 1 is viewed from the normal direction. Therefore, when a predetermined point light source is placed on the surface of card 1 on the observer side, the pattern of light image 230 reproduced in hologram formation area 110 of hologram structure 10 effectively transmits window portion 13 and can be appropriately observed by the observer.

[0104] Furthermore, even if a specific point light source is not positioned on the surface of card 1 facing the observer, if there is some kind of light source, the diffuse reflected light reflected by the vapor deposition layer 170 of the hologram structure 10, etc., changes the visibility of the pattern of the light image 230 of the second printed layer 12 forming the window portion 13, and the visibility with a slight amount of brilliance can give the observer a moderate sense of luxury.

[0105] On the other hand, when the transmission density is less than 0.15, even if there is no point light source, the pattern of the design of the second printed area 12b viewed through the window 13 is perceived as having a strong glossiness due to the diffuse light reflection of the internal hologram structure 10 under the influence of natural light. In this case, it is easy to perceive that a hologram is built into the inside of the card 1, which is disadvantageous in terms of security. For this reason, it is preferable that the transmission density of the second printed area 12b is at least 0.15 or more.

[0106] If the transmission density of the window portion 13 formed by the second printing layer 12 is 0.15 or more and 0.75 or less, the presence of a hologram or the like inside the window portion 13 is difficult for the observer to clearly perceive when a specific point light source is not placed on the observer side. Therefore, the card 1 of this embodiment is usually recognized as a card with only a simple design print without special processing such as a hologram. On the other hand, only when a specific point light source is placed on the observer side, a light image as a hologram appears to emerge in the window portion 13, and the card can be made to appeal to users as an unexpected card. In addition, since the presence of a clear hologram is difficult to perceive, the counterfeit prevention effect can also be improved. EXAMPLES

[0107] The present disclosure will be described in more detail below with reference to examples.

[0108] [Example 1] (a) Formation of master and hologram structure A dry etching resist was spin-coated on the thin chrome film of a photomask blank plate, which had a synthetic quartz substrate and a thin low-reflection chrome film laminated on it, using a spinner. The dry etching resist was ZEP7000 manufactured by Zeon Corporation, and formed to a thickness of 400 nm. This resist layer was exposed to a pattern created in advance by a computer using an electron beam lithography device (MEBES4500: manufactured by ETEC), and the exposed parts of the resist resin were made soluble. A developer was then sprayed (spray development) to remove the soluble parts, forming a resist pattern.

[0109] The grating pitch of the pattern was 3,179 nm. Next, the formed resist pattern was used to dry etch and remove the chromium thin film in the portion not covered with the resist, exposing the quartz substrate. The exposed quartz substrate was then etched to form recesses in the quartz substrate. The resist thin film was then dissolved and removed to obtain an original having recesses formed by etching the quartz substrate and protrusions in which the quartz substrate and the chromium thin film remained unetched. The size of the original, i.e., the size of the hologram cell, was 0.25 mm.

[0110] A composition for forming the hologram layer 160 (UV-curable acrylate resin: refractive index 1.52, measured wavelength 633 nm) was dropped onto a 0.5 mm thick polycarbonate sheet (transparent substrate) to form a coating of the composition. Next, an original plate having projections and recesses was placed on the coating and pressed. Next, the coating was cured by irradiating with active radiation and then peeled off to form a hologram cell having a projection and recess surface that is an inverse of the projection and recess type of the original plate. Then, the original plate was repeatedly placed, pressed, cured, and peeled off to form a 2 μm thick hologram layer 160 having a 15 mm square hologram formation area 110 in which hologram cells were laid out.

[0111] Next, an Al layer having a thickness of 100 nm was formed by sputtering on the entire surface of the hologram layer 160 on the side of the concave-convex surface 130, thereby obtaining the hologram structure 10.

[0112] (b) Card Creation Next, as components of the large-sized card base 2 with multiple cards attached, white core layers 4 and 5 made of PVC with a thickness of 0.36 mm and transparent oversheets 3 and 6 made of PVC with a thickness of 0.1 mm, on which magnetic stripes 7 and 8 were thermally transferred in advance, were prepared. The above-mentioned hologram structure 10 was temporarily attached to one surface of the core 4, and the oversheet layer 6, core layer 5, core layer 4, and oversheet layer 3 were laminated from the -Z direction side toward the +Z direction side, as shown in FIG. 1(b). Here, the hologram structure 10 was embedded in the boundary between the core layer 4 and the oversheet layer 3. In this state, stainless steel plates were applied to the laminated large-sized card base 2 from the +Z direction side and the -Z direction side, respectively, and a predetermined heat and pressure were applied by a heat press machine for a predetermined time, thereby obtaining a large-sized card base 2 in which each layer was heat-fused.

[0113] On the other hand, a release varnish was applied by silk printing or the like, a second printed layer 12 was applied by offset printing or the like, and a first printed layer 11 was applied by silk printing or the like on a PET film. The second printed layer 12 also formed a window portion 13, and the second printed region 12b forming the window portion 13 had several different transmission densities, and samples were created. The window portion 13 was formed in a position and size that included the hologram formation region 110 in a plan view of the window portion 13. The size of the window portion 13 was approximately 15 mm square, the same as the size of the hologram formation region 110.

[0114] The PET film printed in this manner was layered on the surface of the oversheet 3 of the large-sized card base 2 in which the layers were heat-sealed as described above, with the printed layer facing the oversheet 3. Then, stainless steel plates were again applied to the laminated card base 2 from the +Z direction side and the -Z direction side, respectively, and a predetermined heat and pressure were applied for a predetermined time using a heat press machine. As a result, the printed layer was transferred from the PET film to the large-sized card base 2 side. This was punched out to card size using a punching machine to obtain card 1.

[0115] (c) Evaluation When the surface of the card 1 is viewed from the normal direction, the LED light of a smartphone is placed at a position 50 mm from the surface of the card 1 as a point light source, and observed from a position 300 mm away from the surface of the hologram layer. A predetermined image, which is a Fourier transformed light image (the character "OK" in FIG. 10) in a 15 mm square hologram formation area, can be observed with good visibility. Here, the appearance of the light image due to the difference in the transmission density of the second printed area 12b forming the window portion 13 was confirmed, and the results are shown in FIG. 10 together with the image of the light image. The transmission density is the transmission density defined in JIS X6305-1 (2010) measured using the visual filter mode of a model TD904 manufactured by Macbeth. The central part of the area of ​​the second printed area 12b forming the window portion 13 in the card 1 was measured, and the measurement result of the transmission density was obtained. The samples prepared were one in which the second printed region 12b of the second printed layer 12 was not formed, and one in which the transmission density of the second printed region 12b of the second printed layer 12 was 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, and 0.45. The one in which the second printed region 12b of the second printed layer 12 was not formed corresponds to the item "no pattern" in "transmission density and visibility of optical image" in Fig. 10(a).

[0116] As an evaluation result, for the cards not having the second printed region 12b of the second printed layer 12, when the surface of the card 1 is viewed from the normal direction, the LED light of a smartphone was placed as a point light source at a position 50 mm from the surface of the card 1, and the visibility of the light image (the character "OK") was confirmed when observed from a position 300 mm away from the surface of the hologram layer. In addition, for the cards having the second printed region 12b of the second printed layer 12, the visibility of the light image (the character "OK") was confirmed by the same observation as above for each transmission density. The evaluation result of ◎ indicates that the visibility of the light image (the character "OK") was extremely good, ◯ indicates that the visibility of the light image (the character "OK") was good, and × indicates that the visibility of the light image (the character "OK") was not good.

[0117] As a result, as shown in FIG. 10(a), when the transmission density was 0.85 and 0.80, the evaluation result was ×, and when the transmission density was 0.75, 0.70, and 0.65, the evaluation result was ◯. When the transmission density was 0.60, 0.55, and 0.45, the evaluation result was ◎. On the other hand, in FIG. 10(b), when the LED light of the smartphone, which is a point light source, was turned off, it was confirmed whether the pattern of the picture of the second printed area 12b visible in the window portion 13 under the influence of natural light had a strong glossiness due to the diffuse light reflection of the internal hologram structure 10. That is, when the LED light of the smartphone, which is a point light source, was turned off, the results were confirmed in the item "transmission density and the inconspicuousness of the glossiness of the window portion" regarding whether the glossiness of the window portion 13 was too noticeable. The evaluation results indicated that the glossiness of the window portion 13 was not noticeable at all when the LED light of the smartphone, which is a point light source, was turned off, that the glossiness of the window portion 13 was relatively unnoticeable, and that the glossiness of the window portion 13 was unnoticeable, respectively.

[0118] As a result, when the transmission density is 0.10, even when the LED light of the smartphone, which is a point light source, is turned off, the pattern of the picture of the second printed area 12b viewed through the window portion 13 due to the influence of natural light is viewed with a strong glossiness due to the diffuse light reflection of the internal hologram structure 10, and the glossiness of the window portion 13 is reduced in conspicuousness. In other words, at this time, the glossiness of the window portion 13 is more noticeable than necessary, making it easy to perceive that a hologram is built into the inside of the card 1. In this respect, it was found that the security of the card 1 at that transmission density is reduced, so that the transmission density of the second printed area 12b needs to be 0.15 or more. It was also found that if the transmission density of the second printed area 12b is 0.20 or more, the glossiness of the window portion 13 is further reduced in conspicuousness.

[0119] It was found that when the transmission density of the window portion 13 formed in the second printing region 12b of the second printing layer 12 is 0.15 or more and 0.75 or less, the light image pattern created by the hologram structure 10 inside the window portion 13 is perceived well by the observer, and particularly when the transmission density is 0.20 or more and 0.60 or less, the light image pattern is perceived extremely well by the observer. [Explanation of symbols]

[0120] 1 Card 2. Card Base 3, 6 Oversheet layer 4, 5 Core layer 7, 8 Magnetic Stripe 10 Hologram structure 11 1st printing layer 12 2nd printing layer 12a 1st printing area 12b 2nd printing area 13 Window section 20 Patterns 110 Hologram formation area 110a Hologram cell 130 Uneven surface 140 Transparent base material 150 Interlayer adhesive layer 160 holographic layers 170 Deposited layer 210 Observer 220 light source 230, 240 Light image

Claims

1. A card substrate; a hologram structure laminated on a partial area of ​​the card substrate; a surface layer formed of a transparent material and laminated above the card substrate and the hologram structure; A laminate comprising: a printed layer laminated on an upper side of the surface layer, the printed layer includes a window portion which is a printed region having a transmission density of 0.15 or more and 0.75 or less in at least a part of a region overlapping with the hologram structure when the surface of the laminate is viewed from a normal direction, The hologram structure includes a reflection-type hologram forming region in which a phase-type Fourier transform hologram is recorded, the phase-type Fourier transform hologram converting light incident from a point light source into a desired light image; a deposition layer formed in contact with the uneven surface of the hologram forming area, In the hologram formation region, phase information of a Fourier transform image obtained by Fourier transform of an original image is multi-valued and recorded as a depth, The hologram formation region is an array of a plurality of hologram cells capable of converting light incident from a point light source into the optical image.

2. A card substrate; a hologram structure laminated on a partial area of ​​the card substrate; a surface layer formed of a transparent material and laminated above the card substrate and the hologram structure, the surface layer being formed of a transparent material and laminated above the card substrate and the hologram structure when the direction from the card substrate toward the hologram structure is defined as an upper side and the opposite side is defined as a lower side; A printed layer laminated on at least one of the upper and lower sides of the surface layer, the printed layer includes a window portion which is a printed region having a transmission density of 0.15 or more and 0.75 or less in at least a part of a region overlapping with the hologram structure when the surface of the laminate is viewed from a normal direction, The hologram structure includes a reflection-type hologram forming region in which a phase-type Fourier transform hologram is recorded, the phase-type Fourier transform hologram converting light incident from a point light source into a desired light image; a deposition layer formed in contact with the uneven surface of the hologram forming area, In the hologram formation region, phase information of a Fourier transform image obtained by Fourier transform of an original image is multi-valued and recorded as a depth, The hologram formation region is an array of a plurality of hologram cells capable of converting light incident from a point light source into the optical image.

3. a planar size of the hologram formation area is within a range of 5 mm square to 50 mm square, The planar size of the hologram cell is 0.25 mm square or more, The laminate according to claim 2 , wherein the grating pitch of the uneven surface is in the range of 1.0 μm or more and 80.0 μm or less.

4. The laminate according to claim 2 , wherein the window portion of the printed layer has a transmission density of 0.20 or more and 0.60 or less.

5. A concealing layer is further provided between the surface layer and the printing layer, The laminate according to claim 2 , wherein the concealing layer is provided in an area excluding a part of the window portion when the surface of the laminate is viewed in a normal direction.

6. The laminate according to any one of claims 1 to 5, which is a card.

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