Optical element and method for manufacturing the same

Abstract

To manufacture an optical element capable of providing a reflective layer while realizing monolithic bonding.SOLUTION: A method for manufacturing an optical element including a reflective layer includes the steps of: preparing a base material layer; preparing a stamper having a plurality of concave-convex structures provided on a front surface of the stamper; stamping the stamper with its front surface facing a surface of the base material layer, and embossing a relief structure having the plurality of concave-convex structures on the surface of the base material layer; forming the reflective layer by arranging metal for the reflective layer on a portion of the surface of the base material layer on which the relief structure is embossed; and laminating the base material layer and a protective layer in a state where the reflective layer is interposed therebetween by aligning the protective layer with the surface of the base material layer. During laminating, resin of the base material layer and the protective layer flows into a space between the base material layer and the protective layer, and the optical element formed by monolithically bonding the base material layer and the protective layer is manufactured.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical element equipped with a hologram for the purpose of preventing counterfeiting, for example, to protect cards, passports, etc., and a method for manufacturing the same. [Background technology]

[0002] Conventionally, a method for preventing counterfeiting has been known in which an optical element having an optical effect that is difficult to imitate is applied to articles that require counterfeit prevention, such as securities, ID cards, and passports.

[0003] Known optical elements of this type include elements having a hologram, a diffraction grating, a multilayer interference film, and the like.

[0004] In recent years, thermoplastic resins such as polycarbonate have been increasingly used as the base material for ID cards and passports. Among thermoplastic resins, polycarbonate in particular is widely used because it allows on-demand information to be added by laser printing.

[0005] To enhance the anti-counterfeiting effect, a method is known in which a substrate is manufactured by laminating two or more thermoplastic resins and attaching a hologram (diffraction grating) between the layers, or by forming a diffraction grating directly on the thermoplastic resin.

[0006] By sandwiching the hologram between thermoplastic resins and laminating it together to produce ID cards and passports, the optical elements can be protected from physical and chemical damage.

[0007] A method for attaching a hologram to a thermoplastic resin is to provide an adhesive layer on the hologram, while a method for directly forming a diffraction grating on a thermoplastic resin is to apply a hot stamping process to the thermoplastic resin.

[0008] The widespread use of thermoplastic resins is due to the monolithic bonding effect of two or more layers of thermoplastic resin during lamination, which makes it difficult to remove the hologram embedded between the layers, enhancing the anti-counterfeiting effect.

[0009] Generally, ID cards made of thermoplastic resin are made up of three layers: a base layer, a laser printable layer, and a protective layer, which are arranged on both the front and back sides.

[0010] Patent Document 1 discloses a method in which a reflective layer is provided on a thermoplastic resin in advance, the reflective layer is embossed from above with a stamper having a relief structure, fine holes are drilled in the reflective layer, and then lamination is performed. According to this method, the thermoplastic resin bonds through the fine holes, achieving a monolithic bond.

[0011] Furthermore, Patent Document 2 discloses a manufacturing method in which a thermoplastic resin incorporating a hologram is adhered with a thermoplastic adhesive. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] US Patent No. US10105920B2 [Patent Document 2] European Patent No. EP2700510B1 Summary of the Invention [Problem to be solved by the invention]

[0013] However, such a conventional manufacturing method has the following problems.

[0014] That is, in conventional manufacturing methods, when a thermoplastic resin substrate is used, a hologram is generally applied in a spot manner, for example, by attaching a hologram patch coated with an adhesive layer.

[0015] In order to improve the anti-counterfeiting property more than ever before, it is preferable to provide the hologram on the entire surface of the substrate, rather than on a spot.

[0016] However, applying a hologram patch to impart a hologram to the entire surface of a substrate is not practical from the standpoint of cost and counterfeit resistance, so it is possible to emboss a hologram relief structure directly onto a thermoplastic resin substrate and provide a reflective layer.

[0017] However, providing a reflective layer on the entire surface of the substrate results in a configuration in which the reflective layer is placed between thermoplastic resin layers, making it impossible to ensure monolithic bonding between the layers during lamination.

[0018] The monolithic interlayer bonding has the effect of making it impossible to reuse personal information such as a facial photograph or a forgery prevention medium such as a hologram, thereby enhancing the forgery prevention performance.

[0019] However, if monolithic substrate bonding becomes impossible, this effect is lost, resulting in a problem of reduced anti-counterfeiting properties.

[0020] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical element that can be provided with a reflective layer while realizing monolithic bonding, and a method for manufacturing the same. [Means for solving the problem]

[0021] A first aspect of the present invention is a method for producing an optical element incorporating a reflective layer, comprising the steps of: preparing a base layer; preparing a stamper having a plurality of concave-convex structures on its surface; stamping the stamper with its front side facing the surface of the base layer to emboss a relief structure having a plurality of concave-convex structures on the surface of the base layer; arranging a metal for the reflective layer on a portion of the surface of the base layer on which the relief structure is embossed to form a reflective layer; and matching a protective layer to the surface of the base layer, and laminating the base layer and the protective layer with the reflective layer sandwiched between them; during lamination, the resins of the base layer and the protective layer flow into the space between the base layer and the protective layer, thereby producing an optical element in which the base layer and the protective layer are monolithically bonded together.

[0022] A second aspect of the present invention is the manufacturing method of the first aspect, wherein no metal is disposed in the space, or the metal is disposed in a thickness thinner than the surrounding area.

[0023] A third aspect of the present invention is the manufacturing method of the first or second aspect, wherein the step of forming a reflective layer by arranging a metal for the reflective layer on a part of the surface of the base layer embossed with a relief structure includes the steps of arranging a mask having a specified mask pattern so as to cover the surface of the base layer, and vapor-depositing the metal onto the surface of the base layer through the mask.

[0024] A fourth aspect of the present invention is the manufacturing method of the first aspect, wherein the stamper has, on its surface, a first region consisting of a plurality of concave-convex structures having a first aspect ratio and a second region consisting of a plurality of concave-convex structures having a second aspect ratio greater than the first aspect ratio, and the relief structure has, as the plurality of concave-convex structures, a plurality of concave-convex structures having the first aspect ratio and a plurality of concave-convex structures having the second aspect ratio, and in the step of forming a reflective layer by arranging a metal for the reflective layer on part of the surface of the base layer on which the relief structure is embossed, the metal is arranged by vapor deposition, and spaces are formed between the plurality of concave-convex structures having the second aspect ratio, where the vapor-deposited metal is arranged at a thickness thinner than the concave-convex structures having the first aspect ratio.

[0025] A fifth aspect of the present invention is a method for manufacturing an optical element containing a reflective layer, comprising the steps of preparing a base layer, arranging metal for the reflective layer on the surface of the base layer, demetalizing a portion of the arranged metal to form a reflective layer in a desired pattern on the surface of the base layer, and matching a protective layer to the surface of the base layer, and laminating the base layer and protective layer with the reflective layer sandwiched between them; during lamination, the resin of the base layer and the protective layer flows into the space between the portion of the base layer where the metal has been demetalized and the protective layer, thereby manufacturing an optical element in which the base layer and protective layer are monolithically bonded.

[0026] A sixth aspect of the present invention is a monolithic optical element containing a reflective layer, in which when a base layer having a reflective layer arranged on part of its surface and a protective layer arranged to sandwich the reflective layer between the base layer are laminated, the resin of the base layer and the protective layer flows into the part between the base layer and the protective layer where the protective layer is not arranged, thereby monolithically bonding the base layer and the protective layer while containing the reflective layer.

[0027] A seventh aspect of the present invention is the optical element of the sixth aspect, wherein the protective layer is transparent.

[0028] An eighth aspect of the present invention is the optical element of the sixth aspect, wherein the protective layer includes a color-developing layer.

[0029] A ninth aspect of the present invention is the optical element of the sixth aspect, wherein the reflective layer is disposed on a part of the surface of the substrate layer by being partially demetallized. [Effects of the Invention]

[0030] According to the present invention, it is possible to provide an optical element that can be provided with a reflective layer while realizing monolithic bonding, and a method for manufacturing the same. [Brief explanation of the drawings]

[0031] [Figure 1]FIG. 1 is a flowchart illustrating the flow of a method for manufacturing an optical element according to the first embodiment. [Figure 2] FIG. 2 is a side cross-sectional view of a base layer illustrating the method for manufacturing the optical element according to the first embodiment. [Figure 3] FIG. 3 is a side cross-sectional view of a base layer illustrating a method for manufacturing an optical element according to the second embodiment. [Figure 4] FIG. 4 is a plan view showing an example of a mask. [Figure 5] FIG. 5 is a flowchart illustrating the flow of a method for manufacturing an optical element according to the third embodiment. [Figure 6] FIG. 6 is a side cross-sectional view of a base layer illustrating a method for manufacturing an optical element according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc., are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed and redundant explanations will be omitted as appropriate.

[0033] (First embodiment) A method for manufacturing an optical element according to a first embodiment of the present invention will be described.

[0034] FIG. 1 is a flowchart illustrating the flow of a method for manufacturing an optical element according to the first embodiment.

[0035] FIG. 2 is a side cross-sectional view of a base layer illustrating the method for manufacturing the optical element according to the first embodiment.

[0036] In the method for manufacturing an optical element according to this embodiment, first, a substrate layer 10 for the optical element is prepared (S1). The material of the substrate layer 10 can be a transparent plastic. This transparent plastic can be a thermoplastic. The thermoplastic can be a polymer or copolymer of polycarbonate, polyester, polyester terephthalate, or vinyl chloride. The transparent plastic is preferably an amorphous plastic. The crystallinity of the amorphous plastic can be less than 50%.

[0037] After step S1, a stamper 20 having a large number of concave and convex structures on its surface is prepared (S2).

[0038] As illustrated in Figure 2(1), the stamper 20 can have a surface (the surface facing downward in the figure) that is provided with a first region R1 consisting of a plurality of concave-convex structures 21 having a first aspect ratio, and a second region R2 consisting of a plurality of concave-convex structures 22 having a second aspect ratio larger than the first aspect ratio. The pitch of the concave-convex structures in the first region R1 can be set to a short wavelength at which the relative luminosity factor is high and equal to or less than half that wavelength, specifically, equal to or less than 500 nm, equal to or greater than 250 nm. This allows the second region R2 to function as a zero-order diffraction grating, unlike the first region R1, and to obtain different visual characteristics.

[0039] The aspect ratio is the ratio of the height of the concave-convex structure to the pitch of the concave-convex structure. The first aspect ratio can be the average of the aspect ratios of the concave-convex structures 21 in the first region R1, and similarly, the second aspect ratio can be the average of the aspect ratios of the concave-convex structures 22 in the second region R2.

[0040] After step S2, as illustrated in FIG. 2(1), the stamper 20 is stamped onto the surface of the base layer 10 (the surface facing upward in the figure) with the surface on which the first region R1 and the second region 2 are provided, i.e., the surface on which the plurality of relief structures 21, 22 are provided, facing the stamper 20. As a result, a relief structure having a plurality of relief structures 11, 12 is embossed onto the surface of the base layer 10, as illustrated in FIG. 2(2) (S3). The relief structure 11 embossed on the base layer 10 is provided by the relief structure 21 of the first region R1 of the stamper 20, and the relief structure 12 is provided by the relief structure 22 of the second region R2. Therefore, like the relief structure 21, the relief structure 11 also has a first aspect ratio, and like the relief structure 22, the relief structure 12 has a second aspect ratio greater than the first aspect ratio.

[0041] After step S3, as illustrated in Fig. 2(3), a metal 13 or metal compound for a reflective layer is deposited on the surface (the surface facing upward in the figure) of the base layer 10 on which the relief structure is embossed (S4). The deposition of the reflective layer can be performed by, for example, vapor deposition, CVD, or sputtering.

[0042] As a result, metal 13 is laminated by vapor deposition, CVD or sputtering on the relief structure 11 formed by the first region R1 of the stamper 20 in the relief structure embossed on the base layer 10, forming a reflective layer 13.

[0043] On the other hand, in the concave-convex structure 12 formed by the second region R2 of the stamper 20, the metal 13 is also vapor-deposited on the slopes of the concave-convex structure 12. However, because the specific surface area of ​​the concave-convex structure 12 is larger than the specific surface area of ​​the concave-convex structure 11, the thickness of the metal 13 arranged on the slopes of the concave-convex structure 12 is not as thick as the metal 13 stacked on the concave-convex structure 11.

[0044] After step S4, as illustrated in FIG. 2(4), the protective layer 14 is placed on the surface of the base layer 10 (the surface facing upward in the figure), and the base layer 10 and the protective layer 14 are laminated together.

[0045] The protective layer 14 may also be made of a transparent material such as polycarbonate, similar to the base layer 10. The protective layer 14 may also include a color-developing layer (not shown).

[0046] During lamination, the resins of the base material layer 10 and the protective layer 14 enter the space K, and an optical element 15 is produced in which the base material layer 10 and the protective layer 14 are monolithically bonded, as shown in part A (S5). The optical element 15 contains a reflective layer 13 disposed on the relief structure 11.

[0047] Therefore, the optical element 15 can also be used as an anti-counterfeiting hologram by virtue of the internal reflective layer 13.

[0048] According to the method for manufacturing the optical element 15 of the first embodiment, the optical element 15 including the reflective layer 13 therein can be manufactured by laminating the base layer 10 and the protective layer 14 in this manner.

[0049] Next, an example of manufacturing the optical element 15 for a card substrate by the manufacturing method according to the first embodiment will be described.

[0050] A thermoplastic resin was used as the base material layer 10 for the card substrate. Specifically, polycarbonate having a thickness of approximately 200 μm was used.

[0051] A stamper 20 made of a Ni plate having a fine uneven structure was prepared in order to emboss a relief structure into such a polycarbonate substrate layer 10. The Ni plate stamper 20 was produced by the following procedure.

[0052] First, lithography data for an electron beam lithography device (not shown) was created. This lithography data is data for the electron beam lithography device to lithograph the first region R1 and the second region R2 provided on the stamper 20.

[0053] The created drawing data was input to an electron beam drawing device, and the electron beam drawing device was caused to draw the first region R1 and the second region R2 on the Ni plate resist in accordance with this drawing data.

[0054] Next, Ni was sputtered onto the surface of the resist having this relief structure, followed by Ni plating, to produce a Ni stamper 20 having a first region R1 and a second region R2.

[0055] The first region R1 is made up of a large number of concave-convex structures 21, and the average aspect ratio (first aspect ratio) of these numerous concave-convex structures 21 is 0.5 or less. The second region R2 is made up of a large number of concave-convex structures 22, and the average aspect ratio (second aspect ratio) of these numerous concave-convex structures 22 is greater than 0.5, ranging from 0.8 to 2.0.

[0056] Such a Ni stamper 20 was hot stamped onto a polycarbonate substrate layer 10 to emboss a relief structure.

[0057] Furthermore, TiO2 (titanium oxide) was vapor-deposited as metal 13 for the reflective layer onto the surface of the base layer 10 on which the relief structure was embossed (hereinafter referred to as the "embossed surface"). Vapor deposition was carried out until a TiO2 layer with a thickness of several nm was deposited on the uneven structure 11. Note that TiO2 (titanium oxide) is just one example of metal 13 for the reflective layer, and is not limited thereto; for example, ZnS (zinc sulfide) can also be used.

[0058] On the other hand, since the aspect ratio of the concave-convex structure 12 is larger than that of the concave-convex structure 11, the angle of the slope is steeper, and the TiO2 is not stacked so as to cover the upper side of the concave-convex structure 12, but is arranged along the slope of the concave-convex structure 12. Since the specific surface area of ​​the concave-convex structure 12 is larger than the specific surface area of ​​the concave-convex structure 11, the thickness of the TiO2 arranged on the slope of the concave-convex structure 12 is not as thick as the TiO2 stacked on the concave-convex structure 11.

[0059] Next, a protective layer 14 made of the same polycarbonate base material as the base layer 10 was placed on the embossed surface of the base layer 10 and laminated together. The resins of the base layer 10 and the protective layer 14 entered the space K, and the base layer 10 and the protective layer 14 were monolithically bonded together, as shown in part A.

[0060] In this way, it was possible to manufacture an optical element 15 in which the reflective layer 13 can be disposed between the base layer 10 and the protective layer 14 while achieving monolithic bonding. The optical element 15 manufactured in this way can also realize an optical effect by a hologram due to the reflective layer 13 contained therein.

[0061] This is achieved by providing a concave-convex structure 12 with a large aspect ratio and a concave-convex structure 11 with a small aspect ratio on a base material layer 10, and when metal 13 for a reflective layer is vapor-deposited on the base material layer 10, utilizing the space K formed in the concave-convex structure 12 as the space K into which resin flows during lamination.

[0062] In the example shown in FIG. 2(1), the second region R2 is located in the center of the stamper 20. However, this location is merely an example, and the second region R2 can also be located at the edge of the stamper 20. By using a stamper 20 with the second region R2 located at the edge, the uneven structure 12 can be created in an area of ​​5 mm to 20 mm at the four corners or edge of the base layer 10. This makes it easier to prevent peeling of the optical element 15 from the edge, preventing the reflective layer or uneven structure from being peeled off and reused for other cards, etc., or preventing the uneven structure from being illegally duplicated. The uneven structure 12 may be provided intermittently in an area of ​​one-quarter to three-quarters of the length of the edge of the base layer 10. The uneven structure 12 may also be located along the entire edge of the base layer 10.

[0063] (Second embodiment) A method for manufacturing an optical element according to the second embodiment of the present invention will now be described.

[0064] FIG. 3 is a side cross-sectional view of a base layer illustrating a method for manufacturing an optical element according to the second embodiment.

[0065] The flow of the method for manufacturing an optical element according to the second embodiment of the present invention is also illustrated in the flowchart shown in FIG.

[0066] That is, in the method for manufacturing an optical element according to this embodiment, similarly to the first embodiment, a base layer 10 for the optical element is prepared (S1).

[0067] In this embodiment, after step S1, a stamper 20A having a plurality of concave-convex structures on its surface is also prepared (S2), but this stamper 20A has a first region R1 on its surface (the surface facing downward in the figure) that is made up of a plurality of concave-convex structures 21 having a first aspect ratio, as illustrated in Fig. 3(1). However, stamper 20A differs from stamper 20 in that it does not have a second region R2 that is made up of a plurality of concave-convex structures 22 having a second aspect ratio that is larger than the first aspect ratio.

[0068] After step S2, as illustrated in FIG. 3(1), the stamper 20A is stamped onto the surface of the base layer 10 (the surface facing upward in the figure) with the surface on which the first region R1 is provided, i.e., the surface on which the plurality of relief structures 21 are provided, facing up. As a result, as illustrated in FIG. 3(2), a relief structure having a plurality of relief structures 11 is embossed onto the surface of the base layer 10 (S3). The relief structure 11 embossed on the base layer 10 is provided by the relief structure 21 of the first region R1 of the stamper 20A. Therefore, like the relief structure 21, the relief structure 11 also has a first aspect ratio.

[0069] After step S3, as illustrated in Fig. 3(3), a metal 13 for a reflective layer is disposed (S4) while the surface of the base layer 10 embossed with the relief structure (the surface facing upward in the figure) is covered with a mask 30. The metal 13 for the reflective layer can be disposed by vapor deposition or sputtering.

[0070] FIG. 4 is a plan view showing an example of a mask.

[0071] 4, the mask 30 has holes 31 formed in a predetermined two-dimensional pattern. Therefore, when metal 13 is vapor-deposited or sputtered toward the base layer 10 while the upper surface of the base layer 10 is covered with the mask 30, the metal 13 that passes through the holes 31 in the mask 30 is disposed on the surface of the base layer 10, and the reflective layer 13 is laminated on the surface of the base layer 10 in the two-dimensional pattern defined by the mask 30.

[0072] After step S4, as illustrated in FIG. 3(4), the protective layer 14 is placed on the surface of the base layer 10 (the surface facing upward in the figure), and the base layer 10 and the protective layer 14 are laminated to produce the optical element 15 (S5).

[0073] At this time, the resin of the base material layer 10 and the protective layer 14 enters the space K on the surface of the base material layer 10 where the metal 13 is not placed, and the base material layer 10 and the protective layer 14 are monolithically bonded together as shown in part A.

[0074] This allows the production of an optical element 15 that can include a reflective layer 13 while achieving monolithic bonding.

[0075] Next, an example of manufacturing an optical element 15 for a card substrate by the manufacturing method according to the second embodiment will be described.

[0076] A thermoplastic resin was used as the base material layer 10 for the card substrate. Specifically, polycarbonate having a thickness of approximately 200 μm was used.

[0077] A stamper 20A made of a Ni plate having a fine uneven structure was prepared in order to emboss a relief structure into such a polycarbonate base layer 10. The Ni plate stamper 20A was produced by the following procedure.

[0078] First, lithography data for an electron beam lithography device (not shown) was created. This lithography data is data used by the electron beam lithography device to lithograph the first region R1 provided in the stamper 20A. Once created, this lithography data was input into the electron beam lithography device, and the electron beam lithography device was caused to lithograph the first region R1 on the Ni plate resist according to this lithography data. In this way, the stamper 20A was provided with the first region R1 consisting of a concave-convex structure 21 with an average aspect ratio of 0.5 or less. Note that, unlike the stamper 20, the stamper 20A does not have a second region R2 consisting of a concave-convex structure 22 with a high aspect ratio.

[0079] Next, Ni was sputtered onto the surface of the resist having this relief structure, followed by Ni plating, to produce a Ni stamper 20A having the first region R1.

[0080] Such a Ni stamper 20A was hot stamped onto a polycarbonate substrate layer 10 to emboss a relief structure.

[0081] Next, a metal mask 30 for vapor deposition was prepared, which was made to fit the dimensions of the base layer 10. This mask 30 was patterned in advance into an arbitrary shape that matched the relief structure of the Ni plate, as shown in FIG.

[0082] Next, with the upper surface of the base layer 10 covered with a mask 30, TiO2 was vapor-deposited onto the base layer 10 as metal 13 for the reflective layer. This allowed the metal 13 to be deposited on the embossed surface of the base layer 10 while being distributed in the shape patterned by the mask 30. Vapor deposition was continued until a TiO2 layer several nm thick was deposited on the embossed surface.

[0083] Next, the mask 30 was removed, and a protective layer 14, made of the same polycarbonate base material as the base material layer 10, was laminated onto the embossed surface of the base material layer 10 to form a card. During lamination, the resins of the base material layer 10 and the protective layer 14 entered the space K, and the base material layer 10 and the protective layer 14 were monolithically bonded together (S5), as shown in part A. The optical element 15 thus manufactured includes a reflective layer 13 disposed on the relief structure 11.

[0084] In this way, it was possible to manufacture an optical element 15 in which the reflective layer 13 can be disposed between the base layer 10 and the protective layer 14 while achieving monolithic bonding. The optical element 15 manufactured in this way can also realize an optical effect by a hologram due to the reflective layer 13 contained therein. By realizing monolithic bonding while including the reflective layer 13, it is possible to realize both the optical effect by a hologram and excellent physical counterfeit resistance.

[0085] The mask 30 for vapor deposition does not necessarily have to be made of metal, but can also be made of a highly hydrophilic substance such as polyvinyl alcohol. For example, when using a mask 30 made of polyvinyl alcohol, a mask layer made of the polyvinyl alcohol mask 30 can be applied to the embossed surface of the base layer 10 before vapor deposition, and after a metal film is formed by vapor deposition, this mask layer can be removed by washing with water using a lift-off method.

[0086] Alternatively, a mask layer formed by flexographically printing oil onto the base layer 10 can be used as the mask 30, and after vapor deposition, the oil can be removed to obtain a patterned reflective layer region.

[0087] Furthermore, as explained in the first embodiment, the mask 30 may be placed at a position corresponding to the end of the base layer 10 to remove the reflective layer, thereby improving the bonding strength.

[0088] (Third embodiment) A method for manufacturing an optical element according to the third embodiment of the present invention will be described.

[0089] FIG. 5 is a flowchart illustrating the flow of a method for manufacturing an optical element according to the third embodiment.

[0090] FIG. 6 is a side cross-sectional view of a base layer illustrating a method for manufacturing an optical element according to the third embodiment.

[0091] That is, in the method for manufacturing an optical element according to this embodiment, as illustrated in FIG. 6(1), first, a base layer 10 for the optical element is prepared (S11).

[0092] 6(2), a metal 13 for the reflective layer is disposed on the surface of the base layer 10 (S12). The metal 13 for the reflective layer can be disposed by, for example, vapor deposition.

[0093] Next, as illustrated in Fig. 6(3), a portion of the arranged metal 13 is demetalized by a laser L, thereby arranging the metal 13 in a desired pattern on the surface of the base layer 10 (S13). A space K is generated in the demetalized location.

[0094] Next, as illustrated in Fig. 6(4), the protective layer 14 is placed on the surface of the base material layer 10, and the base material layer 10 and the protective layer 14 are laminated together (S14). During lamination, as illustrated in Fig. 6(5), the space K is filled, and an optical element 15 is produced in which the base material layer 10 and the protective layer 14 are monolithically bonded, as shown in part A. The optical element 15 contains a reflective layer 13 arranged on the concave-convex structure 11.

[0095] In this way, the optical element 15 according to this embodiment utilizes the space K formed by demetallizing the vapor-deposited metal 13 as the space K into which the resin flows during lamination. This allows for monolithic bonding while incorporating the reflective layer 13, making it possible to achieve both the optical effect of a hologram and excellent physical counterfeit resistance.

[0096] Although the best mode for carrying out the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to such a configuration. Those skilled in the art may conceive of various modifications and alterations within the scope of the technical ideas of the invention as defined in the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention. [Explanation of symbols]

[0097] 10 Base material layer 11, 12 Uneven structure 13 Metal, reflective layer 14 Protective layer 15 Optical Elements 20, 20A stamper 21, 22 Uneven structure 30 Mask 31 holes K space L Laser R1 1st area R2 2nd area

Claims

1. 1. A method for manufacturing an optical element including a reflective layer, comprising: providing a substrate layer; preparing a stamper having a plurality of relief structures on its surface; a step of stamping the stamper onto the surface of the base layer with the front surface facing the stamper, thereby embossing a relief structure having the plurality of concave-convex structures on the surface of the base layer; forming a reflective layer by disposing a metal for the reflective layer on a portion of the surface of the base layer on which the relief structure is embossed; a step of placing a protective layer on the surface of the base layer and laminating the base layer and the protective layer with the reflective layer sandwiched between them, A manufacturing method for producing an optical element in which the base layer and the protective layer are monolithically bonded together by allowing the resins of the base layer and the protective layer to flow into the space between the base layer and the protective layer during the lamination.

2. The manufacturing method according to claim 1 , wherein the metal is not disposed in the space or is disposed in a thickness thinner than the surrounding area.

3. The step of forming the reflective layer by disposing a metal for the reflective layer on a portion of the surface of the base layer on which the relief structure is embossed includes: placing a mask having a designated mask pattern over the surface of the substrate layer; The method according to claim 1 or 2, further comprising the step of depositing the metal on the surface of the base layer through the mask.

4. the stamper has, on its surface, a first region made up of a plurality of concave-convex structures having a first aspect ratio and a second region made up of a plurality of concave-convex structures having a second aspect ratio larger than the first aspect ratio, as the plurality of concave-convex structures; the relief structure has, as the plurality of concave-convex structures, a plurality of concave-convex structures having the first aspect ratio and a plurality of concave-convex structures having the second aspect ratio; in the step of forming the reflective layer by disposing a metal for the reflective layer on a part of the surface of the base layer on which the relief structure is embossed, the disposing of the metal is performed by vapor deposition of the metal; The manufacturing method according to claim 1 , wherein the spaces are formed between a plurality of concave-convex structures having the second aspect ratio, in which the deposited metal is arranged at a thickness thinner than the concave-convex structures having the first aspect ratio.

5. 1. A method for manufacturing an optical element including a reflective layer, comprising: providing a substrate layer; disposing a metal for the reflective layer on a surface of the base layer; forming the reflective layer in a desired pattern on the surface of the base layer by demetallizing a portion of the disposed metal; a step of placing a protective layer on the surface of the base layer and laminating the base layer and the protective layer with the reflective layer sandwiched between them, A manufacturing method for producing an optical element in which the base layer and the protective layer are monolithically bonded together by allowing the resin of the base layer and the protective layer to flow into the space between the portion of the base layer in which the metal has been demetallized and the protective layer during the lamination.

6. A monolithic optical element including a reflective layer, An optical element in which, when a base layer having a reflective layer disposed on part of its surface and a protective layer disposed so as to sandwich the reflective layer between the base layer and the protective layer are laminated, resins of the base layer and the protective layer flow into the portion between the base layer and the protective layer where the protective layer is not disposed, thereby monolithically bonding the base layer and the protective layer while encapsulating the reflective layer.

7. The optical element according to claim 6 , wherein the protective layer is transparent.

8. The optical element according to claim 6 , wherein the protective layer includes a color-developing layer.

9. The optical element according to claim 6 , wherein the reflective layer is disposed on a portion of the surface of the substrate layer by being partially demetallized.

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