EP3727870B1 - Sicherheitselement mit zweidimensionaler nanostruktur und herstellverfahren für dieses sicherheitselement - Google Patents

Sicherheitselement mit zweidimensionaler nanostruktur und herstellverfahren für dieses sicherheitselement Download PDF

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Publication number
EP3727870B1
EP3727870B1 EP18829361.7A EP18829361A EP3727870B1 EP 3727870 B1 EP3727870 B1 EP 3727870B1 EP 18829361 A EP18829361 A EP 18829361A EP 3727870 B1 EP3727870 B1 EP 3727870B1
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EP
European Patent Office
Prior art keywords
surface elements
security element
base
nano structure
base plane
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP18829361.7A
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German (de)
English (en)
French (fr)
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EP3727870A1 (de
Inventor
Hans Lochbihler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Giesecke and Devrient Currency Technology GmbH
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Giesecke and Devrient Currency Technology GmbH
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/324—Reliefs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/328—Diffraction gratings; Holograms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B42D25/373—Metallic materials

Definitions

  • the invention relates to a security element for a document of value, wherein the security element has a dielectric substrate in which a two-dimensionally periodic nanostructure is formed, which has a plurality of base surface elements that define a base plane and, in contrast, raised or lowered surface elements, with between the base surface elements and the surface elements each have a distance measured perpendicular to the base plane and connecting flanks are formed between the base surface elements and the surface elements, the base surface elements and the surface elements each being covered with a metal layer that is thinner than the distance, and the base surface elements and the surface elements in the nanostructure are arranged alternately in a regular pattern and in two directions that run parallel to the ground plane, the associated period of the arrangement of the surface elements is between 100 nm and 450 nm.
  • the invention further relates to a manufacturing method for such a security element.
  • the DE 102011101635 A1 , DE 102015008655 A1 or DE 102012105571 A1 describe such security elements and manufacturing processes.
  • surface elements that are raised or lowered relative to a metallized base plane are arranged in a two-dimensional pattern and are located above holes of the same size in the metallized base plane.
  • the surface elements act as an antenna and form electromagnetic resonances between the metallization in the ground plane and the surface elements for certain wavelengths. This results in a color for visible light in reflected light and transmitted light. The reflection on the top and bottom is different due to the different area coverage by the metal layer.
  • L. Lin, and Y. Zheng. Multiple plasmonic-photonic couplings in the Au nanobeaker arrays: enhanced robustness and wavelength tunability.”
  • Optics letters, 2060-2063 (2015 ) so-called nanocup arrays made of gold are known, which also produce color effects.
  • the known two-dimensional periodic subwavelength gratings are very complex to produce. Structuring on a subwavelength scale is required in order to form the metal layer in the base plane and the raised or lowered metallized surface elements.
  • the EP 3124283 A1 which discloses a security element according to the preamble of claim 1, describes as well as the EP 3255468 A1 a display element and an observation method for the display element.
  • the DE 10 2012 110 630 A1 discloses a multilayer body and a method for producing a security element.
  • the WO 2014/023415 A1 describes a security element with a structure that creates a color effect and the DE 10 2012 025 262 A1 discloses a method for producing a security element.
  • the invention is based on the object of specifying a two-dimensional, color-filtering structure which, on the one hand, has good color filter properties and, on the other hand, can be manufactured more easily.
  • the security element is designed for a document of value, banknote paper or the like. It has a dielectric substrate. A two-dimensional periodic nanostructure is formed in the dielectric substrate. This defines a large number of base area elements that define a base level. Compared to the base surface elements, there are raised or lowered surface elements in the nanostructure. There is a distance between the base surface elements and the surface elements, which is measured perpendicular to the base plane. The base surface elements and the surface elements are connected to one another by connecting flanks. The nanostructure can therefore be designed, for example, by columnar elevations or depressions in the dielectric substrate. The base surface elements and the surface elements as well as the connecting flanks are covered with a metal layer that is thinner than the distance. The nanostructure is therefore provided with the metal layer throughout.
  • the base surface elements and the surface elements are arranged alternately in a regular pattern. This means that they are periodic in two non-coincident directions that run parallel to the ground plane. The period directions can vary. Overall, the periods in which the surface elements are arranged are between 100 nm and 450 nm, which is where the term “nanostructure” comes from. Instead of a metal layer, another high-index layer can also be used. In addition to metal, silicon, zinc sulfide or titanium dioxide are particularly suitable materials for the high-index layer. In this description, the term “metallic” is taken to be synonymous with “high-refractive index,” unless expressly stated otherwise.
  • a closed metal film is formed on the nanostructure. It covers a variety of elevations and those in between Sections, especially all flanks of the large number of elevations. Unlike in the prior art, in which elevations or depressions of the profile are only covered with metal on the plateaus, a closed metal film is now formed.
  • the nanostructure metallized in this way reflects incident light in the zeroth order of diffraction, whereby an interference effect occurs that changes the color of the reflection, so that a color effect is created.
  • the uncoated nanostructure consists of a dielectric material, which z. B. has a refractive index of about 1.5.
  • Plastic films are particularly suitable, e.g. B. PET films as a substrate.
  • the actual basic structure is e.g. B. also made of plastic, preferably UV varnish, or is created by thermoplastic deformation of the film. After vapor deposition, the structure is finally filled with UV varnish and laminated with a cover film. This results in a layer structure in which the top and bottom have essentially the same refractive index.
  • the following materials are suitable for the metal layers: Al, Ag, Pt, Pd, Au, Cu, Cr and alloys thereof.
  • ZnS, ZnO, TiO 2 , ZnSe, SiO, Ta 2 O 5 or silicon are particularly suitable as high-index layers.
  • a dielectric with the nanostructure is first suitably structured and then coated over the entire surface. It is preferred that the nanostructure is embedded in an embedding dielectric, which preferably has the same refractive index as the dielectric of the substrate.
  • the refractive index can be between 1.4 and 1.6, for example. However, the same refractive index on the bottom and top of the structure is not essential for the desired optical effect.
  • the color effects of the two-dimensional nanostructure strongly depend on the periodicity of the pattern. This is used in further training to create colored symbols or images.
  • the area filling factor and/or the distance between the area elements and base area elements is varied locally.
  • DE 102011101635 A1 known to design a group of several surface elements and base surface elements laterally with constant dimensions so that a desired color effect occurs. This group then forms a sub-pixel. Several sub-pixels are given different color properties through appropriate geometric design and then combined into one pixel. This allows a colored image display.
  • the different colors can be varied by the corresponding local variation of one or more of the parameters of the grid (distance between surface elements and base surface elements, periods of the pattern in two spatial directions and extent of the surface elements).
  • basic colors pixel by pixel e.g. B. RGB colors
  • true color images can be produced in subpixel areas.
  • the advantage of such structures compared to conventional printing technology is that very fine motif structuring down to the micrometer range can be carried out. However, no complex sampling of metallization, etc. is required since the metal layer can be formed continuously. This fine structuring is particularly suitable for applications in moiré magnification arrangements, as also in DE 102011101635 A1 described.
  • the substrate with the coated two-dimensional periodic nanostructure can be used in particular in a security element for a document of value. It can be used in particular in a security thread, Tear thread, security tape, security strip, patch or label can be integrated.
  • the security element provided with the grid can span transparent areas or recesses.
  • the substrate with the two-dimensional periodic nanostructure with a closed metal film shows pronounced color effects in reflection.
  • the desired color can be adjusted by choosing structural parameters of the nanostructure.
  • the distance between surface elements and base surface elements i.e. the height of the elevations or depressions, comes into question.
  • Another question is the period or the different periods of the arrangements of elevations and depressions in the spatial directions parallel to the ground plane.
  • Another possible parameter is the dimensions of the surface elements and their geometric shape in plan view. This can be rotationally symmetrical. In other designs it has a two-fold symmetry, for example it is rectangular or elliptical.
  • the proportion of the expansion of the surface element in the period is also a variable parameter that influences the color effect.
  • These parameters can of course be varied laterally across the security element in order to vary the color effect and thus create a motif.
  • a colored motif or a true-color image in reflection can easily be provided by arranging nanostructure sections with laterally different structural parameters.
  • the structures can be made by simply embossing. A metallic coating, for example vapor deposition, then takes place. This layer then no longer needs to be structured in a complex manner, but rather covers the nanostructure over the surface. In this way, security elements with optical properties that cannot be counterfeited can be produced cost-effectively in large series.
  • the color of the structure results from the embossing and not from a structuring of the metallization, which can, for example, be carried out very cost-effectively in aluminum.
  • the security element can in particular be part of a not yet fit for circulation (e.g. banknote paper) to a document of value, which can additionally have further authenticity features so that the later documents of value have non-copiable authenticity features in order to enable an authenticity check and to prevent unwanted copies.
  • Bank or credit cards or ID cards are examples of a document of value.
  • Banknote paper is an example of a precursor.
  • Figure 1 shows a color-filtering nanostructure 1, which is intended to form a security element S for a document of value.
  • the nanostructure 1 is produced in that a carrier 2 is provided with a profile that has elevations with lateral flanks 4 above a base surface 5. The sides form the flanks 4 and the top surface form surface elements 3.
  • the nanostructure is provided with a metal layer 6, which is applied both to the base surface 5 and to the surface elements 3.
  • the flanks 4 are also provided with the cover layer 6.
  • Figure 1 shows an embodiment in which the elevations have a rectangular or square cross section in a top view of a base plane defined by the base layer 5
  • Figure 2 an embodiment with round elevations.
  • the elevations are arranged in the form of a two-dimensional periodic pattern, with at least one period d being provided along two mutually perpendicular directions in the base plane defined by the base surface, according to which the arrangement of the elevations is repeated.
  • the Figures 3A to 3B show different embodiments for the profile of the nanostructure in cross section, for example along the direction in which the extension w 2 is present. In Figure 3A the profile is trapezoidal. In Figure 3B is the profile opposite the Figure 3A inverted. Instead of elevations, there are depressions.
  • the profile representations of the Figures 3A to 3B clearly show that the elevations 7 or depressions 8 in the surface elements are also provided with the metal layer as on the flanks 4. Likewise, the metal layer 6 is provided in the remaining base surface elements 9 of the base surface 5, which as a result is continuous and over the entire surface . If unpolarized light falls on the nanostructure 1 at an angle ⁇ , it is reflected in the zeroth order of diffraction.
  • the grating period d is smaller than the wavelength of the visible light spectrum and lies in the range between 100 nm and 450 nm.
  • the nanostructure 1 is in two spatial directions Basic level 5 periodically. The period can be different in both directions. Periods with different periods can show a polarization effect.
  • the metal layer 6 has a refractive index v. It is embedded in a dielectric with the refractive index n through the nanostructure 1 on the substrate 2 and a cover lamination 10. This is preferably a UV varnish that is located on a film, for example PET film, which forms the substrate 2.
  • the refractive index of both materials is around 1.5.
  • the thickness of the metal layer is between 20 nm and 150 nm. It is marked t in the figures.
  • a rounded structure often results from the manufacturing process, as strictly sharp-edged corners, as in the Figures 3A and 3B , are very difficult or even impossible to achieve in practice with embossing processes with nanostructure fineness.
  • the Figures 4 to 6 show possible patterns in which the elevations 7 or depressions 8 can be arranged.
  • the structure of the pattern can be orthogonal ( Figure 4 ) or hexagonal ( Figures 5 and 6 ) be.
  • the periods d are in the subwavelength range, ie in the range between 100 nm and 450 nm.
  • the filling factors w 1 /d 1 and w 2 /d 2 are between 0.2 and 0.8, preferably between 0.3 and 0.7.
  • the periodicity directions are perpendicular to one another. This is also optional. Spatially asymmetrical arrangements of the profile and periodicity are also conceivable. In other words, pattern 6 does not have to, as in Figure 1 shown to be a Cartesian pattern.
  • the columns 4 can also be designed asymmetrically.
  • the following materials are suitable for the metal layers: Al, Ag, Pt, Pd, Au, Cu, Cr and alloys thereof.
  • ZnS, ZnO, TiO 2 , ZnSe, SiO, Ta 2 O 5 or silicon are suitable as high refractive index layers.
  • the dielectric carrier is formed with the elevations 7 or depressions 8 arranged in the pattern and then coated. It is important that the coating 6 is coherent, i.e. the flanks 4 are also coated.
  • the nanostructures can be reproduced in a molding process so that cost-effective mass production can be achieved.
  • Nanoimprint processes are particularly suitable for this.
  • Transparent areas can also be realized within the structure described above, for example by laser demetallization in areas or by a wash color process.

Landscapes

  • Credit Cards Or The Like (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)
EP18829361.7A 2017-12-19 2018-12-19 Sicherheitselement mit zweidimensionaler nanostruktur und herstellverfahren für dieses sicherheitselement Active EP3727870B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102017130589.0A DE102017130589A1 (de) 2017-12-19 2017-12-19 Sicherheitselement mit zweidimensionaler Nanostruktur und Herstellverfahren für dieses Sicherheitselement
PCT/EP2018/085914 WO2019121964A1 (de) 2017-12-19 2018-12-19 Sicherheitselement mit zweidimensionaler nanostruktur und herstellverfahren für dieses sicherheitselement

Publications (2)

Publication Number Publication Date
EP3727870A1 EP3727870A1 (de) 2020-10-28
EP3727870B1 true EP3727870B1 (de) 2024-02-07

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EP18829361.7A Active EP3727870B1 (de) 2017-12-19 2018-12-19 Sicherheitselement mit zweidimensionaler nanostruktur und herstellverfahren für dieses sicherheitselement

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EP (1) EP3727870B1 (zh)
CN (1) CN111511571B (zh)
DE (1) DE102017130589A1 (zh)
WO (1) WO2019121964A1 (zh)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113763801A (zh) * 2021-09-08 2021-12-07 中国科学院微电子研究所 防伪结构、防伪结构的制备方法和芯片
DE102022000102A1 (de) * 2022-01-12 2023-07-13 Giesecke+Devrient Currency Technology Gmbh Optisch variables Flächenmuster

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011101635A1 (de) * 2011-05-16 2012-11-22 Giesecke & Devrient Gmbh Zweidimensional periodisches, farbfilterndes Gitter
DE102012105571B4 (de) 2012-06-26 2017-03-09 Ovd Kinegram Ag Dekorelement sowie Sicherheitsdokument mit einem Dekorelement
DE102012015900A1 (de) * 2012-08-10 2014-03-06 Giesecke & Devrient Gmbh Sicherheitselement mit farbeffekterzeugendem Gitter
DE102012110630A1 (de) * 2012-11-06 2014-05-08 Ovd Kinegram Ag Mehrschichtkörper sowie Verfahren zur Herstellung eines Sicherheitselements
DE102012025262B4 (de) * 2012-12-21 2020-06-04 Giesecke+Devrient Currency Technology Gmbh Verfahren zur Herstellung eines Sicherheitselementes
EP3450196B1 (en) * 2014-03-27 2020-06-10 Toppan Printing Co., Ltd. Display body and observing method for display body
JP6641738B2 (ja) * 2015-02-04 2020-02-05 凸版印刷株式会社 表示体、および、表示体の観察方法
US20180043724A1 (en) * 2015-03-06 2018-02-15 Ccl Secure Pty Ltd Diffractive device producing angle dependent effects
DE102015008655A1 (de) 2015-07-03 2017-01-05 Giesecke & Devrient Gmbh Sicherheitselement mit farbfilterndem Gitter

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CN111511571B (zh) 2021-11-23
WO2019121964A1 (de) 2019-06-27
EP3727870A1 (de) 2020-10-28
DE102017130589A1 (de) 2019-06-19
CN111511571A (zh) 2020-08-07

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