JP2012192585A - Transfer foil, transfer medium, and method of manufacturing transfer foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce surface reflection with a simple method, enhance optical effects due to hologram and a diffraction structure, and provide added value to a commercial product by anti-counterfeiting effects, in a transfer foil having an OVD and attached to a medium which is the commercial product when used.SOLUTION: The transfer foil includes: an adhesive layer; a diffraction structure formation layer located on the adhesive layer; and a reflection layer arranged on the diffraction structure side of the diffraction structure formation layer. A reflection reduction structure is provided on a side opposite to the diffraction structure side on the diffraction structure formation layer. The reflection reduction structure is composed of a minute irregular structure having 250-400 nm of a distance between apexes and 0.25 or more of an aspect ratio.

Description

  The present invention relates to a transfer foil having an optical variable device (OVD) typified by a diffraction grating, which is transferred to a medium requiring security, and a method for manufacturing the same.

  Conventionally, a relatively inexpensive OVD has been used as a forgery prevention technique for labels, tags, and the like. This OVD expresses three-dimensional images and special decorative images using light interference, and changes color depending on the viewing angle, such as holograms, diffraction gratings, and multilayered thin films with different optical properties. Shift).

  OVD requires advanced manufacturing technology, has a unique visual effect, and can determine authenticity at a glance. Therefore, OVD is formed on a part of or the entire surface of credit cards, securities, certificates, etc. as an effective counterfeiting measure. Is being used.

  Recently, in addition to securities, it is affixed to sports equipment, computer parts and other electrical product software, etc., as an authentication sticker that proves the authenticity of the product, and as a seal sticker that is affixed to the package of those products Is also widely used.

  When the transfer foil having this OVD is viewed, it is viewed in a state in which reflected light from the surface is included in addition to the effect light by OVD, and the reflected light increases depending on the angle. When the number is larger than that, it works as noise and the effect of OVD is diminished.

  As a method of reducing the reflected light on the surface, the metal foil layer adhered to the plastic sheet surface is overlapped with the fine uneven surface of the matte sheet having the fine uneven surface, and pressed with a pressure plate, the metal foil There has been proposed a metal foil matting method characterized in that the surface of the metal foil layer is matted by imparting the fine irregularities to the layer surface (Patent Document 1).

  Using a shaped film in which matte fine irregularities made of a releasable binder resin with a matting agent added on a base film are partially provided, and at least a matting agent on the matte fine irregularities of the shaped film There has been proposed a matte transfer foil characterized in that a matte resin layer made of a resin to which is added is laminated (Patent Document 2).

  In addition, in the transfer foil in which at least a release agent layer is provided on the transfer mount, the release agent layer is formed with a material that can cause peeling in the layer, and adhesion between the transfer mount and the release agent layer. A transfer foil characterized in that the strength is higher than the peel strength in the release agent layer has been proposed. This forms a mat on the surface by inducing cohesive failure of the release layer during transfer (Patent Document 3).

  However, these three points are for matting the outermost surface or film in bulk, and are proposals for providing an irregular reflection layer. Therefore, the reflected light is light having no diffraction effect or interference effect, and the color does not change depending on the viewing angle. Therefore, the reflected light on the surface causes the diffraction effect that is an effect as an OVD as an original anti-counterfeit medium. There is a problem that the interference effect is reduced.

As a method for reducing surface reflection without reducing the effect as OVD, a low reflection layer in which a low refractive index layer, a high refractive index layer, and a medium refractive index layer are laminated in this order has been proposed. . However, providing a multilayer film as a low reflection layer is very complicated in production (Patent Document 4).

JP 2002-10295 A Japanese Patent No. 3164619 Japanese Patent No. 3023930 JP 2004-9420 A

  Transfer foil used by attaching OVD to a product medium is used to prevent counterfeiting and add value to the product, but the optical effect of holograms and diffraction structures is caused by reflection on the surface of the transfer foil. It is difficult to see and its optical effect is not sufficient. Therefore, a simple method is to reduce the reflection of the surface, enhance the optical effect of the hologram or diffraction structure, and add value to the product by the forgery prevention effect.

  As means for solving the above problems, the invention described in claim 1 includes an adhesive layer, a diffractive structure forming layer on the adhesive layer, and a reflective layer provided on the diffractive structure side of the diffractive structure forming layer. A transfer foil provided with a reflection reducing structure on a side opposite to the diffraction structure side on the diffraction structure forming layer, the reflection reduction structure having a fine vertex interval of 200 to 400 nm and an aspect ratio of 0.25 or more. It is a transfer foil characterized by comprising an uneven structure.

  According to the second aspect of the present invention, there is provided a character, a symbol or a pattern-free region having a fine uneven structure in the region where the reflection reducing structure is formed. The transfer foil according to claim 1, wherein

  The invention described in claim 3 is a transfer medium obtained by transferring the transfer foil according to claim 1 or claim 2.

  According to a fourth aspect of the present invention, a reflectance reduction structure forming layer is provided on a substrate, and a reflectance reduction structure composed of a fine concavo-convex structure is formed on the surface of the reflectance reduction structure formation layer. A diffractive structure forming layer is stacked, a diffractive structure is formed on the diffractive structure forming layer, and a reflective layer and an adhesive layer are sequentially stacked, and peeling is performed at the interface between the reflectivity reducing structure forming layer and the diffractive structure forming layer. A method for producing a transfer foil, wherein a fine concavo-convex structure provided in a reflectance-reducing structure forming layer is manufactured by producing a stamper having a fine concavo-convex structure having a vertex interval of 200 to 400 nm and an aspect ratio of 0.25 or more. The method for producing a transfer foil is characterized in that the fine concavo-convex structure is transferred and formed.

  The invention according to claim 5 is the method for producing a transfer foil according to claim 4, wherein the fine uneven structure of the stamper is formed in a character or pattern.

  The reflected light on the outermost surface of the transfer foil having the OVD function is reduced by reducing the reflected light without reducing the OVD effect light by providing a reflectance reduction structure on the surface, and the OVD effect of the transfer foil. The security can be improved by maximizing this.

It is a conceptual diagram when the transfer foil of this invention is seen from the front. It is a conceptual diagram when the 2nd transfer foil of this invention is seen from the front. It is the conceptual diagram which showed sectional drawing about the transfer foil of this invention. It is the section conceptual diagram showing the state where the transfer foil of the present invention was transcribe | transferred to the material to be transferred. In the manufacturing method of the transfer foil of this invention, it is the conceptual diagram which showed the process of transferring the reflectance reduction structure part formed in the stamper to the reflectance reduction structure formation layer on a support body. In the manufacturing method of the transfer foil of this invention, it is the conceptual diagram which showed the process of forming the reflectance reduction structure part formed in the stamper in the reflectance reduction structure formation layer on a support body by light irradiation. It is the conceptual diagram which showed the state by which the reflectance reduction structure part was shape | molded in the manufacturing method of the transfer foil of this invention. In the method for manufacturing a transfer foil provided with the non-reflectance reducing structure according to the present invention, the step of forming the reflectance reducing structure formed on the stamper on the reflectance reducing structure forming layer on the support by hot pressing is shown. It is a conceptual diagram. In the method for manufacturing a transfer foil provided with the non-reflectance reducing structure according to the present invention, the step of forming the reflectance reducing structure formed on the stamper on the reflectance reducing structure forming layer on the support by light irradiation is shown. It is a conceptual diagram. It is the conceptual diagram which showed the state by which the reflectance reduction structure part was shape | molded in the manufacturing method of the transfer foil which provided the non-reflectance reduction structure part of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 shows the transfer foil 1 transferred to the transfer object 16 of the present invention, and the diffractive structure 3 is observed. The reflectance reduction structure 3 is formed on the reflection part 4 and the diffractive structure 3, and the reflected light on the surface is reduced, so that the optical effect can be seen efficiently.

  FIG. 2 shows a state in which the reflectance reduction structure portion 2 formed on the reflection portion 4 and the diffractive structure portion 3 is provided in a pattern. When tilted, a pattern appears due to the difference in intensity of reflected light. Is shown. The “TOP” character pattern can be observed depending on the angle because the non-reflectivity reducing structure 5 is formed in which the reflectance reducing structure 2 is not formed only in the character pattern “TOP”. That is, by providing a region without a fine concavo-convex structure in the region where the reflection reducing structure is formed, it is possible to obtain a structure in which characters, symbols, patterns, etc. are floated due to the difference in intensity of reflected light.

  FIG. 3 is a conceptual diagram showing a cross-sectional view of the transfer foil 1 of the present invention, in which a reflectance-reducing structure forming layer 12 is laminated on a support 11, and the surface of the reducing structure-forming layer 12 has a reflectance-reducing structure. Part 2 is formed, a diffractive structure forming layer 13 is laminated thereon, a diffractive structure part 3 is formed on the surface of the diffractive structure forming layer 13, and a reflective layer 14 is provided on the surface of the diffractive structure part 3, Further, an adhesive layer 15 is laminated.

  FIG. 4 is a conceptual cross-sectional view showing a state in which the transfer foil 1 of the present invention has been transferred to the transfer object 16. During transfer, the transfer foil 1 is peeled off from the interface between the reflectance-reducing structure forming layer 12 and the diffraction structure forming layer 13 and transferred. A reflectance reduction structure 2 is formed on the surface of the foil.

  5, FIG. 6 and FIG. 7 show a method for forming the reflectance reducing structure 2 formed on the surface of the transfer foil 1 of the present invention, and the reflectance reducing structure forming layer laminated on the support 11. 12 and the stamper 21 having the reflectance reduction structure portion 2 formed on the surface thereof are overlapped, set on a transparent fixing jig 23, and irradiated with curing light (ultraviolet light) 22, whereby the surface of the reflectance reduction structure forming layer 12 is irradiated. The process of forming the reflectance reduction structure part 2 is shown.

  8, 9, and 10 show a method for manufacturing a transfer foil having the reflectance reduction structure portion 2 of the present invention provided in a pattern and having the non-reflectance reduction structure portion 5, and is laminated on the support 11. The reflectivity-reducing structure forming layer 12 and the stamper 21 on which the reflectance-reducing structure portion 2 and the non-reflectivity-reducing structure portion 5 are formed are overlapped, set on the transparent fixing jig 23, and irradiated with the curing light 22 This shows the step of forming the reflectance reduction structure portion 2 on the surface of the reflectance reduction structure forming layer 12.

  A diffractive structure forming layer 13 is further laminated on the reflectance reducing structure forming layer 12 having the formed reflectance reducing structure 2, and a diffractive structure 3 such as a hologram or a diffraction grating is formed on the surface of the diffractive structure forming layer 13. Using a stamper, transfer molding is performed by hot pressing.

  Furthermore, a thin film of metal or metal oxide is formed on the surface of the diffractive structure 3 on the surface of the diffractive structure forming layer 13 as a reflective layer 14 by a vacuum resistance heating method or an EB heating method, and an adhesive layer 15 is further provided thereon for transfer. Manufacture foil. When an adhesive is used as the adhesive layer 15, it is necessary to bond release paper.

  The manufactured transfer foil 1 is used after being transferred to the transfer object 16. When the support 11 is peeled off after transfer, the transfer foil 1 is peeled off from the interface between the reflectance-reducing structure forming layer 12 and the diffractive structure forming layer 13. The reflectance reducing structure 2 on the surface of the foil 1 appears.

  The structure of the reflection reducing structure 2 in the present invention is an uneven structure having a vertex interval of 200 to 400 nm and an aspect ratio of 0.25 or more. In principle, since the vertex interval is 200 to 400 nm, which is a smaller scale than the visible light wavelength, there is no strengthening due to light interference in the visible light wavelength range (400 nm to 700 nm) due to irregularities, and the aspect ratio is 0.25 or more This is because the scattering / reflection is suppressed and the scattering is reduced by defining the depth direction of the concavo-convex structure, and it is possible to prevent the diffracted light from being emitted in the normal direction regardless of the incident angle of the irradiated light. If the vertex interval is too small, the depth becomes shallow even when the aspect ratio is maintained, so that reflection increases. For this reason, the vertex interval is preferably 200 nm or more.

  The arrangement pattern of the concave portions or the convex portions in the concavo-convex structure is not limited to a matrix shape or a honeycomb shape, and may be an arrangement pattern with another periodicity such as a rectangular lattice or a random convex portion pattern. It is only necessary that the reflectance reduction structure portion 2 is formed two-dimensionally on the surface of at least the diffraction structure forming layer.

  In the transfer foil 1 in which the reflection reducing structure 2 is formed on the entire surface shown in FIG. 7, the reflection on the surface is reduced and only the diffracted light is visible, so that the diffraction efficiency is improved. In the foil in which the reflection reducing structure 2 is formed in the pattern shown in FIG. 10, the anti-counterfeiting effect is enhanced because the pattern of the presence or absence of reflected light on the surface can be confirmed in addition to the diffracted light depending on the viewing angle.

  The materials used for the support 11, the reflectance-reducing structure forming layer 12, the diffractive structure forming layer 13, the reflecting layer 14, and the adhesive layer 15 constituting the present invention will be described.

  The substrate 1 is a film or sheet made of a resin such as polyethylene terephthalate (PET) and polycarbonate (PC), and is required to be transparent in order to cure the reflectance-reducing structure forming layer 12.

  A photocurable resin or the like can be used for the reflectance-reducing structure forming layer 12. For example, epoxy (meth) acryl, urethane (meth) acrylate, etc. can be used.

A thermoplastic resin or a thermosetting resin can be used for the diffraction structure forming layer 13. For example, acrylic resins include acrylic resins, epoxy resins, cellulose resins, vinyl resins, and the like.

  In addition, urethane resins, melamine resins, phenol resins, and the like obtained by adding polyisocyanate as a crosslinking agent to an acrylic polyol or polyester polyol having a reactive hydroxyl group and crosslinking can be used. The thickness is preferably 0.5 to 5.0 μm.

  The reflective layer 14 can be made of aluminum, gold, silver, copper, Sn (tin), alloys containing these metals, metal oxides or sulfides, and the thickness is preferably 100 to 1000 mm.

  The reflective layer 14 is patterned by vapor deposition in a pattern using a mask, the vapor deposition layer 14 is provided on the diffractive structure forming portion 5, and a transparent resin coating liquid is provided thereon as a resist and dried. The pattern can also be formed by removing the reflective layer 14 made of the exposed deposited film with a post-etching solution. In the case where an aluminum vapor deposition film is used as the reflective layer 14, it is known that an aqueous sodium hydroxide solution is used as an etching solution.

  For the adhesive layer 15, thermoplastic resins such as polyester resin, acrylic resin, vinyl chloride resin, polyamide resin, polyvinyl acetate resin, rubber resin, ethylene-vinyl acetate copolymer resin, vinyl chloride acetate copolymer resin can be used. The film thickness is preferably 1 to 20 μm.

  A concavo-convex structure having an apex interval of 2050 to 400 nm and an aspect ratio of 0.25 or more is generally obtained by drawing an electron beam on an EB resin coated on a glass substrate to obtain a concavo-convex structure. A stamper 21 is formed by forming a thin film of gold or silver on the formed concavo-convex structure and performing metal plating thereon.

  The prepared stamper 21 is used as it is, and the reflectance-reducing structure forming layer 12 is heated and pressurized, cured by irradiating ultraviolet rays or an electron beam from the substrate side, and the surface-reduced reflectance reducing structure portion 2 is transferred and molded. In general, however, the stamper 21 is duplicated and used.

  The diffractive structure 3 can also be formed by the same method. The stamper 13 having the diffractive structure 3 is used as the diffractive structure forming layer 13, and the diffractive structure 3 is heated and pressed to form a transfer.

  When the produced transfer foil 1 is attached to the transfer object 16 and the substrate 1 is peeled off, the transfer foil 1 is peeled off at the interface between the reflectance-reducing structure forming layer 12 and the diffraction structure-forming layer 13, and the transfer foil 1 has a reduced reflectance on the surface. The diffractive structure forming layer 13 having the structure portion 2 is formed.

Examples will be described in detail below. On one side of a support 11 made of a transparent polyethylene terephthalate film having a thickness of 25 μm, a composition having the following blending ratio was applied as a reflectance-reducing structure forming layer 12 by a gravure printing method at a coating thickness of 3 μm and a drying temperature of 110 ° C. Formed.
<Reflectance reduction structure forming layer>
Unsaturated group-containing urethane resin 100 parts Photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals) 1.5 parts Release agent (acrylic silicone BYK-3700 manufactured by Big Chemie) 3 parts Solvent (methyl ethyl ketone) 400 parts Thereafter, vertex interval A nickel stamper (matrix) having a fine concavo-convex structure with a thickness of 350 nm and an aspect ratio of 0.5 is heat-welded to the film at a linear pressure of 500 N / cm at 130 ° C. In this state, a metal halide lamp is used from the support side. It was cured by irradiation with a light amount of 200 mJ / cm 2. And this embossed film is nickel stamper (matrix)
To obtain an embossed film on which a reflectance reducing structure was formed. In order to further increase the surface hardness, a light amount of 300 mJ / cm 2 was additionally exposed from the embossed surface with a high-pressure mercury lamp in a nitrogen atmosphere.

As the diffraction structure forming layer, a composition having the following blending ratio was applied at a coating thickness of 2 μm and a drying temperature of 110 ° C. by a gravure printing method.
<Diffraction structure forming layer>
Mixture of vinyl chloride-vinyl acetate copolymer and urethane resin 25 parts Solvent (methyl ethyl ketone) 70 parts (toluene) 30 parts Nickel stamper (matrix) having a diffractive structure with an apex interval of 0.05 mm and an aspect ratio of 0.1 The film was heated and pressed at a linear pressure of 500 N / cm and 180 ° C. to be cured. And this embossed film was peeled from the nickel stamper (matrix), and the embossed film in which the diffraction structure was formed was obtained.

  An Al thin film, which is a metal thin film, is provided as a reflective layer 14 on the entire surface of the formed diffractive structure to a thickness of 80 nm by vacuum deposition, and then the pattern mask is temporarily aligned with the diffractive structure forming portion. Then, the portion of the metal reflective layer where the pattern mask was not provided was removed by alkali treatment.

Next, as an adhesive layer, a composition having the following blending ratio was applied by a gravure printing method at a coating thickness of 4.0 μm and a drying temperature of 110 ° C.
<Adhesive layer>
Polyester resin 30 parts Solvent (toluene) 40 parts (Methyl ethyl ketone) 40 parts The transfer foil produced as described above was transferred to a medium to be transferred (paper) to obtain an anti-counterfeit article, and the produced anti-counterfeit article was visually observed. . Compared to the conventional transfer foil with diffractive structure, the transfer foil with diffractive structure according to the present invention is provided with a latent image by the reflected light on the foil surface, and the effect of preventing forgery is enhanced.

DESCRIPTION OF SYMBOLS 1 ... Transfer foil 2 ... Reflectivity reduction structure part 3 ... Diffraction structure part 4 ... Reflection part 5 ... Non-reflectance reduction structure part 11 ... Support body 12 ... Reflectivity Reduction structure forming layer 13 ... Diffraction structure forming layer 14 ... Reflective layer 15 ... Adhesive layer 16 ... Transfer 21 ... Stamper 22 ... Curing light 23 ... Transparent fixing jig

Claims (5)

  A transfer foil comprising an adhesive layer, a diffractive structure forming layer on the adhesive layer, and a reflective layer provided on the diffractive structure side of the diffractive structure forming layer, facing the diffractive structure side on the diffractive structure forming layer A transfer foil, characterized in that a reflection reduction structure is provided on the side, and the reflection reduction structure is composed of a fine concavo-convex structure having a vertex interval of 200 to 400 nm and an aspect ratio of 0.25 or more.   The character, symbol, or pattern is raised by a difference in intensity of reflected light by providing a region without a fine uneven structure in the character, symbol, or pattern in the region where the reflection reducing structure is formed. 2. The transfer foil according to 1.   A transfer medium obtained by transferring the transfer foil according to claim 1.   A reflectance-reducing structure forming layer is provided on a base material, a reflectance-reducing structure comprising a fine concavo-convex structure is formed on the surface of the reflectance-reducing structure forming layer, and then a diffraction structure-forming layer is laminated, A method for producing a transfer foil in which a diffractive structure is formed on a structure-forming layer, and further a reflective layer and an adhesive layer are sequentially laminated, and peeled off at the interface between the reflectance-reducing structure-forming layer and the diffractive structure-forming layer. A fine concavo-convex structure provided in the reduced structure forming layer is formed by producing a stamper having a fine concavo-convex structure with an apex interval of 200 to 400 nm and an aspect ratio of 0.25 or more, and transferring the fine concavo-convex structure of the stamper. A method for producing a transfer foil characterized by the above.   5. The method for producing a transfer foil according to claim 4, wherein the fine uneven structure of the stamper is formed in a character or a pattern.