AU2016225899B2

AU2016225899B2 - Safety and/or valuable document having a photonic crystal

Info

Publication number: AU2016225899B2
Application number: AU2016225899A
Authority: AU
Inventors: Oliver Muth; Malte Pflughoefft
Original assignee: Bundesdruckerei GmbH
Current assignee: Bundesdruckerei GmbH
Priority date: 2007-02-08
Filing date: 2016-09-09
Publication date: 2018-02-01
Anticipated expiration: 2028-02-06
Also published as: DE102007007029A1; WO2008095481A3; EP2118855B1; CN101652800B; AU2008213463A1; WO2008095481A2; AU2014203815A1; CN101652800A; CA2677418A1; CA2677418C; AU2016225899A1; EP2118855A2

Abstract

Abstract. The invention relates to a security and/or valuable document having a security element, wherein the security element has a photonic 5 crystal arranged on a substrate with an orienta tion defined, in relation to a surface of the substrate, and a luminescent substance. It is characterized in that an emission wavelength lambda of the luminescent substance, and a grid 10 constant of the photonic crystal are aligned with each other and specified according to the formula lambda = m * 2 * d, wherein d is a dis tance between two lattice planes of the photonic crystal, and m is a positive integer.

Description

The invention relates to a security and/or valuable document having a security element, wherein the security element has a photonic crystal arranged on a substrate with an orientation defined· in relation to a surface of the substrate, and a luminescent substance. It is characterized in that an emission wavelength lambda of the luminescent substance, and a grid constant of the photonic crystal are aligned with each other and specified according to the formula lambda = m * 2 * d, wherein d is a distance between two lattice planes of the photonic crystal, and m is a positive integer.

2016225899 09 Sep 2016

Security and/or valuable document having a photonic crystal

Field of the invention.

The invention relates to a security and/or valuable document having a security element, wherein the security element has a photonic crystal arranged on a substrate with an orientation defined in relation to a surface of the substrate, and a luminescent substance. The invention further relates to a method for the pro15 duction thereof and to a method for the verificat ion thereof .

Background of the invention and prior art.

In valuable and security printing, optically variable colors are established as good security features, since they can easily be verified without technical means. In the practice, such optically variable colors are for instance known from banknotes and documents. They cannot easily be reproduced, but verification for instance at a cash desk is often made by a quick glance only, so that only the presence of a color change is' observed. Because of the plurality of colors and pigments, for instance liquid crystals or platelets or flakes, which have such ef30 fects and are commercially available, impression forgeries are known, which are clearly different from the original color change colors, are how2

2016225899 09 Sep 2016 ever not easily detectable by a layman.

Another widely used security system comprises the use of luminescent substances. In most documents of valuable and security printing are 5 found luminescences, since they are not reproducible with simple means (printer, copier) and require for verification a UV light source only. It is however disadvantageous that in most cases a quick verification only according to the color 10 impression is made, so that a luminescence can in part be imitated for instance with a text marker. For a precise investigation, on the other hand, expensive spectrometers are necessary, by means of which different luminescence 15 wavelengths can be differentiated. Thereby, machine verification is easy and reliable, but the equipment is substantial and thus expensive.

From the document WO 2006/045567 A2, a security and/or valuable document of the structure mentioned above is known. Herein, as a photonic crystal, a layer is used, which is composed of spheres with a tight monomodal diameter distri1 bution, the spheres forming a close-packing of spheres, i.e. a crystal structure. The diameter of the spheres is in a range from 50 to 500 nm, so that for different components of the visible light different reflection conditions according to the Bragg's law at different lattice planes of the crystal result. Thereby, an optically variable color effect is obtained, namely when the security and/or valuable document is swiveled or viewed under changing viewing angles. According to this prior art, the security and/or valuable document may additionally contain a lu35 minescent substance. The diameter of the spheres

H:yz«Ml5ier«W0n\NRPoribhDCCyzn>M9O43_l.<lOC»11/n7/2nH

2016225899 09 Sep 2016

-3is however selected, such that the desired optically variable effects are obtained, and that completely independent from a potential luminescence.

Structures suitable for the production of photonic crystals are for instance described in the documents WO 03/025035 A2, US 4,391,928, EP 0 441 559 BI and EP 0 955 323 BI.

Luminescence radiation typically has no directional characteristic, since the emitter centers are statistically oriented within a coating, ink or the like. From other technical sectors, for instance the technology of laser diodes, it is known to generate directed luminescence radiation by using layer structures, the layers of which have a thickness which leads to the reflection or forward amplification of the luminescence radiation in a defined direction in space. Such structures are less suitable for valuable and security printing because of the expensive production.

Basics of the invention.

The invention teaches that an emission wavelength

2016225899 09 Sep 2016 lambda of the luminescent substance, and a grid constant of the photonic crystal are aligned with each other and specified according to the f o rmu 1 a lambda - m * 2 * d, wherein d is a distance between two lattice planes of the photonic crystal, and m is a positive integer .

In other words, the particles, by which the photonic crystal is formed, are adjusted with regard to diameter and arrangement to the emission wavelength such that the intensity of the luminescence radiation is different under different viewing angles.

By the invention, a substantial improvement of the safe and simple verification of luminescent security elements is achieved. Then a verifying person needs only expose the security and/or valuable document to a radiation exciting the luminescence, for instance UV, and verify,

i) whether luminescence is observed, and ii) if < ' yea, whether the intensity thereof varies when the security and/or valuable document tilts. Only when both criteria are met, the security and/or valuable document is accepted as real. A luminescent security element according to the invention is not reproducible anymore with simple means.

The invention benefits of the finding that a photonic crystal can also be used for providing the per se undirected luminescence radiation by refraction with an anisotropic distribution of the intensity in the solid angle.

2016225899 09 Sep 2016

Definitions .

Security and/or valuable documents are for instance: identity cards, passports, access allowance cards, visas, control symbols, tickets, driver licenses, vehicle documents, banknotes, cheques, postage stamps, credit cards, chip cards and adhesive labels (e.g. for product protection) . Such security and/or valuable documents typically comprise a substrate, a printing layer and optionally a transparent cover layer.

A substrate is a carrier structure, on which the printing layer with information, pictures, patterns and the like is applied. Materials for a substrate may be all usual materials on a paper and/or plastic basis.

A security element is a structural unit, which comprises at least one security feature. A security element may be an independent structural unit, which can be connected with a secu20 rity and/or valuable document, for instance glued, it may however also be an integral component of a security and/or valuable document. An example for the former is for instance a visa to be glued on a security and/or valuable document.

An example for the latter is an areal construct integrated, for instance laminated, in a banknote or an ID card. These are also layers or coatings, which are applied on a substrate.

A security feature is a structure, which can only be produced, reproduced, manipulated or modified with increased efforts (compared to simple copying) or not at all without authorization. For the purpose of the invention, the security feature is formed by the compound struc2016225899 09 Sep 2016 ture of photonic crystal and luminescent substance, The term compound structure denotes the optical coupling with adjustment of the distance of the lattice planes and emission wavelength.

The term luminescence signifies the emission of electromagnetic radiation, in particular in the IR, visible or UV range, in the course of a relaxation of an atomic or molecular electronic system from an excited state into an energeti10 cally lower state, in general the electronic ground state. The previous excitation can be effected by electrical energy or an electrical potential ( elektroluminescence ) , impact of electrons ( cathodo1uminescence) , impact of photons (phot o lumi ne s ce nee) , application of heat (thermoluminescence) or friction (tribo1uminescenoe) , For the purpose of the invention, photoluminescence is preferred. The luminescence comprises in particular the phosphorescence and the (photo)fluorescence.

Fluorescence is a radiating deactivation of excited states, wherein the transition from the excited state into an energetically lower state, for instance the ground state, is spin-al1 owed .

The retention time in the excited state typically is.approx. 10’⁸ s, i.e. the emission of the fluorescence radiation stops immediately after the end of the energy supply for the excitation. Phosphorescence however is a spin-forbidden de30 activation of excited states by intercombination processes. Therefore, the relaxation is weak and slow. The retention time in an excited state is several milliseconds to hours and correspond7

2016225899 09 Sep 2016 ingly long is the emission time of the phosphorescence radiation.

The emission wavelength of a luminescent substance is characteristic for the used substance and is determined by the energy difference between excited state and the energetically lower electronic state, for instance the ground state. The emission wavelength is the peak of the emission intensity in an emission spectrum.

A luminescent substance contains atoms, molecules or particles, which are suitable for luminescence. With a luminescent substance, a luminescent color or ink can be produced, which contains the usual other components of colors or inks, such as binding agents, penetration agents, preservation agents, biocides, tensides, buffer substances, solvents (water and/or organic solvents), filling materials, pigments, effect pigments, anti-foam agents, anti-deposi20 tion agents, UV stabilizers, etc. Suitable ink formulations for different printing methods are well known to the average man skilled in the art, and luminescent substances used according to the invention are added in lieu of or in ad25 dition to conventional dyes or pigments.

A radiation is typically functional for the excitation of the luminescence, when the wavelength of the radiation is smaller than the wavelength of the luminescence radiation. However, a radiation with higher wavelength may also be functional, when the respective luminescent substance is capable of so called up-conversion processes.

2016225899 09 Sep 2016

A lattice plane is defined in space by the Miller indices h, k, and 1. The distance d is defined as the smallest distance of parallel lattice planes, i.e. of lattice planes having the same Miller indices.

A close-packing of spheres corresponds to a fee (face centered cubic, cubic close-packing of spheres) or hcc or hep (hexagonal close packed, hexagonal close-packing of spheres) lattice. The grid constant a is a = 2°·⁵ * D,

D being the diameter of the spheres, which is

given	as the	distance of	the next	adjacent
sphere	centers	•
The	reflection condition	according to	Bragg's
law is:
lambda = m	* 2 * d
whe rein	d is	the distance	between the	lattice
planes ,	and m	is a positive	integer (order), in

particular 1, 2 , 3 , 4 , 5, 6, 7, 8, 9 , or 10. In the following, the calculations are made with m = 1 (1^st order) .

d and a have the following relation: d = a / (h² + k² + I²) °·⁵.

For the relation between the emission wavelength lambda and the diameter D of the spheres follows :

D = [ (h² + k² + I²) / 8 ] ⁰'⁵ * lambda

- 9 2016225899 09 Sep 2016

D = (n / 8]⁰ ·⁵ * lambda, when (h² + k² + I²) is replaced by n.

The term diameter D denotes the mean diameter of the spheres (or means distance of the next adjacent spheres), which is defined as the maximum of a number-referred (monomodal) linear standardized density distribution. This density distribution is given by q_r (x) = dQ_r /dx wherein q_r is the density distribution, Q_r(x) the cumulative sum distribution, referred to the number and dx is the diameter differential.

For the purpose of the invention, the density distribution should be as tight as possible, in order that clearly visible and reproducible angular dependencies occur when viewing. It is preferred, if the density distribution (in most cases similar to a Gauss distribution) has a width at half maximum of the density of less than 10 % of the (mean) diameter D, preferably less than 5 % of the diameter D, ideally less than 2 % of the diameter D.

If instead of spheres other particle shapes, such as platelets or small rods, are used, a tight size distribution in the above meaning is also important. Instead of the mean diameter D then the mean equivalent diameter Dx is used, which is calculated according to defined geometric rules from the respective shape. In this case, too, a correspondingly tight distribution of the aspect ratio (different geometric extensions of a particle) is important.

2016225899 09 Sep 2016

V. )

For the purpose of the invention, it will usually be provided that the photonic crystal has at the emission wavelength no complete band gap. Photonic crystals with complete band gap are up to now only theoretically postulated and are characterized by that the light cannot propagate in any direction in space. For photonic crystals with incomplete band gap, as in particular used for the purpose of the invention, the propagation of the light is in contrast only possible in certain directions in space.

Embodiments of the invention.

In principle, the luminescent substance can emit in the 1R, visible, or UV ranges. It is preferred, if the emission takes place in the visible range, since then a verification of the security and/or valuable document can be made by simple visual inspection.

The luminescent substance may comprise a lu20 minescent dye and/or a luminescent pigment.

The luminescent dye may be selected from the group comprising organic fluorescent dyes, naphthalimides, coumarins, xanthenes, thioxanthenes, naphtholactams, azlactones, methines, oxazines, thiazines, and mixtures of two or more such different substances. The luminescent pigment may be selected from the group comprising Z n S : A g, Z n silicate, Sic, ZnS, CdS (activated with Cu or Mn) , ZnS/CdS : Ag, ZnS : Cu,Al, Y₂0₂S :

Eu, Y₂0₃ : Eu, YV0₄ : Eu, Zn₂SiO₄ : Mn, CaVV0₄, (Zn,Mg)F₂ : Mn, MgSiO₃ : Mn, ZnO : Zn, Gd₂0₂S : Tb, Y₂ 0 ₂S : Tb, La₂ 0₂ S : Tb, BaFCl : Eu, LaOBr : Tb, Mg

2016225899 09 Sep 2016 tungstenate, ( Zn, Be) silicate : Mn , Cd borate : Mn,

Caio(P04)gF , C1 : Sb, Mn, (SrMg ) ₂P₂01 : Eu, Sr₂PzO₇:Sn,

Sr,|Al₁₄O2₅ : Eu, Y₂SiO₅ : Ce,Tb, Y(P,V)0₄ : Eu,

BaMg2AlioO27 : Eu, MaAlijOj? : Ce,Tb, and mixtures of 5 two or more such different substances. Herein, the host lattice is placed before the and a doping element is placed behind the

It is preferred, if the luminescent substance Y is a fluorescent dye, which is selected from the group comprising organic fluorescent dyes, naphthalimides, coumarins, xanthenes, thioxanthenes, naphtho 1 actams, azlactones, methines, oxazines, thiazines, and mixtures of two or more such different substances. With regard to fur15 ther suitable and preferred fluorescent dyes, reference is made for instance to the documents Schwander et al., Fluorescent Dyes in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag GmbH & Co. KGaA, 2002, WO 03 / 20 0 5 2 0 2 5 A, WO 02 / 0 5367 7 A, EP 0 1 4 7 2 52 A, GB

2,2 58,659 and F.M. Winnik et al., Xerox Discloser Journal Vol. 17, No. 3, 1992, pages 1611 62 .

i. j

For the purpose of invention, advantageously 25 two or more different luminescent substances can also be used, the different luminescent substances having different emission wavelengths. The term different emission wavelengths denotes a wavelength difference of at least 3 nm, 5 nm,

10 nm, 20 nm, or 30 nm, in the visible range.

Because of the different emission wavelengths, different angles result, at which the different colors of the luminescence can respectively be observed with particularly high or low inten35 sity. The term high intensity denotes with re12

2016225899 09 Sep 2016 gard to an emission wavelength the maximum intensity to be observed, A low intensity then in contrast denotes a reduced intensity compared to the high intensity, for instance reduced by at least 5 %, 10 %, 20 %, 30 %, 50 %, or 80 %.

Thereby, a luminescence color change is generated, when the security and/or valuable document tilts .

The photonic crystal is advantageously formed by an fee or hcc lattice with a grid constant a, and wherein d = a / n^0,5 with n = 1 to 20, in particular 1 to 5, is, and wherein n is (h² + k^z+ I²) with h, k, and 1 as Miller indices. The lattice points or particles of the photonic crystal may in principle have any shape, for instance as platelets or small rods. It is however preferred, if the lattice points or particles are configured as spheres,

Then it is particularly preferred, if the spheres are core-mantle particles, which are arranged in a close-packing of spheres. The mean diameter to be adjusted of the spheres depends from the emission wavelength of the used luminescent substance. The mean diameter of the spheres may be in the range from 27 0 to 5,000 nm, in particular from 270 to 2,500 nm, if the luminescent substance emits in the IR range (780 to 3 , 00 0 nm) . The mean diameter of the spheres may be in the range from 135 to 1 , 200 nm, in particular from 135 to 600 nm, if the luminescent substance emits in the visible range (380 to 780 nm), The mean diameter of the spheres may be in the range from 35 to 600 nm, in particular from 35 to 3 00 nm, if the luminescent substance emits in the UV range (100 to 380 nm) ,

Ο

CM

2016225899 09 Sep

The photonic crystal can be produced by deposition from the liquid phase by means of selforganization, for instance under pressure, as for the ink jet printing process. For instance the production of artificial opals of Si0₂ from solutions is well known.

crystal, structure, a photonic long-range

It is particularly preferred, if the coremantle particles comprise a core of an organic or inorganic core material and a mantle of a 10 polymeric organic mantle material, the mantle material being flowable at an increased temperature, however the core material not being flowable at the increased temperature. The background is that for the formation of the necessary periodic for instance the c1ose-packing of spheres, must be produced in a defined orientation. If a filling or emulsion or suspension with such core-mantle particles is exposed at an increased temperature to a pressure force, the shearing forces acting between the particles will cause that the particles will arrange and align to a close-packing of spheres on a surface of a substrate, if the particles can move with 25 regard to each other. A mantle being flowable under the pressure and temperature conditions facilitates such organizational movements of the particles relative to each other, and a photonic crystal with excellent long-range and unique 30 orientation on the substrate will result. In detail, there are different possibilities of execution .

The inorganic core material can be selected from the group comprising metals, semimetals, metal chalcogenides, in particular metal oxides,

2016225899 09 Sep 2016 metal pnictides, in particular metal nitrides or metal phosphides, and mixtures of two or more such different substances, wherein the metal can be formed of an element of the first three main groups of the periodic table or of a metallic element of the side groups and wherein the semimetal may comprise Si, Ge, As, Sb, and Bi, is in particular selected from the group comprising S i 0 2, T i 0 ₂, Z r 0 2, SnC>2 and A1₂ 0 3 .

.)

Preferably, the organic core material is selected from the group comprising aliphatic, aliphatic/aromatic or fully aromatic polyesters, polyamides, polycarbonates, polyurea, polyurethanes, aminoplast resins, phenoplast resins, such as for instance formaldehyde condensates of melamine, urea or phenol, epoxide resins, acrylesters, such as methyl (methtacrylate, butyl (meth)acry1 ate, isopropyl (meth)acrylate , polystyrene, PVC, po1yacry1nitrile, random or block copolymerisates of one or several such homopolymers, and mixtures of two or more such different homopolymers or copolymers. ' λ

The mantle material may be selected from the group comprising aliphatic, aliphatic/aromatic or fully aromatic polyesters, polyamides, polycarbonates, polyurea, polyurethanes, aminoplast resins, phenoplast resins, as for instance formaldehyde condensates of melamine, urea or phenol, epoxide resins, po1yepoxides, poly (meth)30 acrylate, such as polymethyl (raeth)acrylate, polybutyl (meth)acrylate, po1yisopropy1 (meth)acrylate, polystyrene, PVC, polyacry1nitrile, polyethylene, polypropylene, polyethylene oxide, polybutadiene, po1ytetrafluorethy lene, polyoxy35 methylene, caoutchouc, po 1 y i s op r en e, random or

2016225899 09 Sep 2016 block copo1ymerisates of one or several such homopolymers, and mixtures of two or more such different homopolymers or copolymers.

It is suitable, if the core material has a higher glass temperature than the mantle material, since then at a temperature between the glass temperatures of the materials, only the mantle material and not the core material will flow. The core material may for instance have a glass temperature in the range of more than 60 °C, preferably more than 80 °C, most preferably more than 90 °C, whereas the mantle material may for instance have a glass temperature in the range from 40 to 90 °C, in particular from 60 to

80 °C. Such ranges of the glass temperatures are recommended for instance for core materials of organic polymer. Alternatively, for instance in the case of inorganic core materials, the glass temperature of the core material may be above

30 0 °C, and then the glass temperature of the mantle area, for instance in the case of polycarbonates, may also be high, for instance in the range from 80 to 2 50 °C, in particular 120 ' . t o 2 0 0 ° C.

The mantle material, which during the production of the photonic crystal may form a matrix, in which the spheres or cores are embedded (and fixed), should have a refractive index being different from the refractive index of the core material. The term different refractive indices denotes a difference of at least 0.001, better at least 0.01, advantageously at least 0.1. The man skilled in the art can easily select, from the above substances for the core material and the mantle material, suitable substance pairs

2016225899 09 Sep 2016 with regard to the difference of the refractive indices. The core material, but also the mantle material may have the respectively higher refract ive index .

The weight ratio of core material and mantle material may be in the range from 2:1 to 1:5, in particular in the range from 3:2 to 1:3. Preferably, this ratio is in the case of polymeric materials for both materials not larger than

2 : 3 .

Between core and mantle of a core-mantle particle, a coupling layer may be provided. For this purpose, for instance cross-linked or partially cross-linked organic polymers can be used. Alternatively, the surface of the core can be functionalized in a conventional manner for a binding or adhesion of the mantle material.

The production of core-mantle particles suitable for the production of photonic crystals is for instance described in the prior art mentioned above, same as further variants and details for core materials, mantle materials, coupling layers, etc. Reference is explicitly made to this prior art.

Photonic crystals to be used according to the invention may be films, layers or foils. Correspondingly, they can be applied with usual coating methods, or adhesion mediators on a substrate. Herein, they may form an integral part of a document, for instance in the case of card structures .

Photonic crystals according to the invention

2016225899 09 Sep 2016 may represent a visible pattern, for instance the contour of an object or a person, or a sequence of letters and/or numbers. Bar codes may also be used as patterns. Then the coating is 5 performed with a corresponding printing method, or a film is correspondingly cut out. It is understood that a photonic crystal may also be formed in a macroscopically isotropic manner, i.e. without pattern.

s /

For the arrangement of the luminescent substance there are different possibilities. The luminescent substance may be arranged in the particles of· the photonic crystal. In the case of core-mantle particles, an arrangement in the core material and/or in the mantle material of the core-mantle particles is possible. For this . purpose, in the case of an organic core material, the respective material is mixed before the solidification or polymerization during the production of the particles with the luminescent substance in a preferably homogeneous manner. In the case of an inorganic core material, a doping producing the luminescence, for instance with ) rare earth elements, may be made, which are in25 tegrated in the host lattice of the core material. Then the photonic crystal can be produced without addition of luminescent particles, thereby disturbances of the creation of the photonic crystal because of the presence of inter30 stitial luminescent particles being safely avoided .

In the case of polymeric materials for core and/or mantle sections of the core-mantle particles, the respective polymer may comprise lumi35 nescent monomer components, and that regularly,

2016225899 09 Sep 2016 statically, block-wise or as side chains (graft copolymers) , Further, in the case of a crosslinked polymer, the cross-linkage means may be luminescent. Finally, luminescent substances may be bound to the polymeric chain in a covalent, ionic or complexed manner. .

The luminescent substance may however also be arranged between the particles of the photonic lattice. In the case of pigments, it is recom10 mendable, if the ratio of the diameter D_p of the pigment particles and the diameter D (or Da) of the particles of the photonic lattice, Dp/D (or Dp/Dft) , is smaller than 0.5, preferably smaller than 0,1, most preferably smaller than 0.02, 15 Then the pigment particles can be arranged between the particles or spheres of the photonic crystal and damages to the particles or spheres by pressure actions is practically excluded. If the luminescent substance is a luminescent dye, 20 it can anyway freely distribute itself between the particles of the photonic lattice, without disturbing these particles or their arrangement. In either case, the production of the photonic crystal is achieved by mixture of particles of 25 the photonic crystal with the luminescent substance and subsequent formation of the longrange order to a crystal, as described above. A variant of this is, if the luminescent substance is deposited on the surface of the particles of 30 the photonic crystal, for instance by layer-bylayer absorption. Thereby, a uniform growth on the particles of the photonic crystal is achieved, with the consequence of the tight density distribution. It geous, herein, that the particles of the photonic crystal and the luminescent substance maintaining is advanta19

2016225899 09 Sep 2016 can be selected and modified independently from each other, thus an easier adjustment to different products of valuable and security printing being possible.

Alternatively, the photonic crystal can also be underlaid with the luminescent substance. For instance, the substrate can be coated, for instance imprinted with a dye or an ink, which comprises the luminescent substance. Then the 10 application of the photonic crystal is made on the coating, for instance in the simplest case as a film. This variant is technologically the simplest one and also permits in this way modifications of the system luminescent substance / photonic crystal, for instance for different types or values of security and/or valuable documents .

Finally, it is possible that in the photonic crystal and/or in a layer comprising the luml20 nescent substance, additional non-luminescent coloration means, such as dyes or pigments, are provided. For this purpose, all coloration means ) being usual in the sector of the security and/or valuable documents and being known to the aver25 age man skilled in the art, can be used.

Equally, conventional forensic characteristic substances can be provided in the photonic crystal or another layer of the security and/or valuable document.

The invention further relates to a method for producing a security and/or valuable document according to the invention or a security element therefor, wherein a substrate is provided on a surface or partial surface with a coating com20

2016225899 09 Sep 2016 prising the particles.of the photonic crystal to be formed, and this coating is condensed under simultaneous exposure to heat and pressure, optionally before coating with the particles, a luminescent layer comprising the luminescent substance being applied to the substrate, and/or the particles comprising the luminescent substance or being mixed therewith. In this embodiment of a production method, the formation of the photonic crystal occurs with the condensation .

Preferably, the exposure to heat takes place with a temperature in the range from 60 to 260 °C, in particular from 70 to 190 °C, and for a time from 0,5 to 7 , 200 s, preferably from 0.5 to

3,600 s, most preferably from 1 to 10 s. The condensation can be performed with a pressure from 1 to 100 bars, preferably from 1 to 20 bars. Typically, the condensation is achieved by means of a press, in particular a lamination press. In the case of an inorganic core material in connection with a polymer having a high glass temperature as mantle material, for instance in

(. ) the range from 80 to 250 °C, the exposure to heat is made at a correspondingly higher temperature, for instance at 140 to 250 °C,

On the coating with particles of the photonic crystal, a separation and/or protection layer can be arranged, welded during the to the substrate,

The protection layer can be and pressure luminesexposure to heat if applicable to the cent layer, and to the layer with particles or can be laminated so to form a layer system. The protection layer should be transparent, referred to the emission wavelength lambda.

2016225899 09 Sep 2016

Alternatively to the above procedure, a security and/or valuable document according to the invention can also be produced by that a finished photonic crystal, in particular in the form of a film (thickness e.g. 0.1 to 5 00 pm), is positioned on the substrate and connected therewith, either by gluing or by laminating. Herein, too, the luminescent substance can already be present in the photonic crystal. It is however possible here, too, that before the substrate is provided with a separate coating, for instance a printing layer, comprising the lumi-

	ne s ce nt	substance ,
	The	invention further relates	t 0	a security
15	and/or	valuable document, which	i s	obtainable
	with an	above method according to	the	invent ion .

Finally, the invention relates to a method for verifying a security and/or valuable document or security element according to the inven20 tion, wherein the luminescent substance is excited to the emission of a luminescence radiation, for instance by exposure to UV radiation, the intensity of the luminescence radiation being determined in dependence on the angle with respect to the surface of the security and/or valuable document, and the determined angular dependency of the luminescence radiation being compared to a given angular dependency. If no angular dependency is determined, or the deter30 mined angular dependency is not in agreement with the given angular dependency, then it is not a security and/or valuable document according to the invention and consequently it is a reproduction. In case of agreement of the deter35 mined angular dependency with the given angular

2016225899 09 Sep 2016 dependency, the security and/or valuable document is verified as being according to the invention and consequently real. The determination can in the simplest case be made by means of visual inspection. It is however also possible to determine the angular dependency by machine. In the case of different luminescent substances, the determination is performed for the respective emission wavelengths, for which different angular dependencies are given.

In the following, the invention is described in more detail with reference to embodiments representing examples of execution only.

Example 1: Different forms of construction of a 15 security and/or valuable document according to the invention.

In Figure 1, cross sections of different variants of security and/or valuable documents according to the invention are shown.

<

v.

In Figure la can be seen a substrate 1, which can be single-layer or multi-layer. On this substrate is immediately applied a printing layer 2, which contains two different fluorescent substances in a uniform distribution, A first fluo25 rescent substance has an emission wavelength of

500 nm, and a second fluorescent substance has an emission wavelength of 7 07 nm. In the layer sequence then follows a photonic crystal 3 configured as a film. This photonic crystal 3 is formed of core-mantle particles according to the document WO 2003/ 025 035 A2 . The core-mantle particles have a mean diameter of the particles of

2016225899 09 Sep 2016

354 nm. To the photonic crystal 3 then follows a protection layer 4 being transparent for visible light, which in turn may be single-layer or multi-layer. It is also possible that between

S the printing layer 2 and the photonic crystal 3, a single-layer or multi-layer intermediate layer is arranged, which is not shown for clarity reasons. The substrate 1 with the printing layer 2, the photonic crystal 3 and the protection layer

4 are connected to each other by lamination and form a monolithic layer block.

In the variant of Figure lb, the same fluorescent substances are used, which are however arranged in the photonic crystal 3. Thereby, the printing layer 2 is not needed. The fluorescent substances are absorbed or adsorbed at the surface of the core-mantle particles, in a uniform distribution .

Example 2 Angular dependency of the fluores20 cence of the subject matterof Example 1 ·

When adjusting the emission wavelengths to the diameter of the particles of the photonic crystal 3, and thus ultimately also to the grid constant a and the distance d of the lattice planes of the photonic crystal 3, it results that red (707 nm) is emitted with a maximum intensity at approx. 45° with respect to the surface normal of the security and/or valuable document, however at 0° and 90° the intensity is strongly reduced, typically below 90 % of the maximum intensity. In contrast, green (500 nm) can be observed at 45° with only 10 % or less of

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-24the maximum intensity, however at 0° and 90° with maximum intensity.

The representation of Figure 2a is obtained, which is a projection of the hemisphere shown in perspective in Figure 2b in the direction of the surface normal of the security and/or valuable document. Sections R can be seen, which appear in red at approx. 45°, whereas the sections G appear in green at approx. 9 0⁰ and 0⁰.

The reference in this specification to any prior publication (or information derived from it) , or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word comprise, and variations such as comprises or comprising, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

EDITORIAL NOTE

The claim numbering has a discontinuity.

The claim set has number claims 1 to 16 and 18 to 20.

Missing claims 17 There are only 19 claims

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Claims

Patent claims.

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FIGIq

FIGIb

1. A security and/or valuable document having a security element, wherein the security element has a photonic crystal

5 arranged on a substrate with an orientation defined in relation to a surface of the substrate, and a luminescent substance, characterized in

10 that an emission wavelength lambda of the luminescent substance and a grid constant of the photonic crystal are aligned with each other and specified according to the formula lambda = m * 2 * d wherein d is a distance between two lattice planes of the photonic crystal, and m is a positive integer.

2. The security and/or valuable document according to claim

20 1, wherein the luminescent substance emits in the IR, visible, or UV range.

3. The security and/or valuable document according to claim 1 or 2, wherein the luminescent substance comprises a luminescent

25 dye and/or a luminescent pigment.

4. The security and/or valuable document according to claim 3, wherein the luminescent dye is selected from the group comprising organic fluorescent dyes, naphthalimides,

30 coumarins, xanthenes, thioxanthenes, naphtholactams, azlactones, methines, oxazines, thiazines, and mixtures of two or more such different substances, and/or wherein the

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-262016225899 08 Jan 2018

luminescent pigment . is selected from the group comprising ZnS : Ag, Zn silicate, SiC, ZnS, CdS (activated with Cu or Mn) , ZnS/CdS : Ag, ZnS : Cu,Al, Y202S : Eu , Y203 : Eu, YV04 : Eu, Zn2SiO4 : Mn, CaVV04, (Zn,Mg)F2 : Mn, MgSiO3 : Mn, ZnO : Zn, 5 Gd202S : Tb, Y202S : Tb, La202S : Tb, BaFCl : Eu, LaOBr : : Tb, Mg tungstenate, ( Zn,Be) silicate : Mn, Cd borate : Mn, CalO(P04) 6F,C1 : Sb,Mn, (SrMg)2 P207 : Eu, Sr2P207 : Sn,

Sr4A114025 : Eu, Y2SiO5 : Ce,Tb, Y(P,V)04 : Eu, BaMg2A110027 : Eu, MaA111019 : Ce,Tb, and mixtures of two or more such

10 different substances.

5. The security and/or valuable document ac-cording to one of claims 1 to 4, wherein the luminescent substance is a fluorescent dye, which is selected from the group comprising

15 organic fluorescent dyes, naphthalimides, coumarins, xanthenes, thioxanthenes, naphtholactams, azlac-tones, methines, oxazines, thiazines, and mixtures of two or more such different substances.

20

6. The security and/or valuable document according to one of claims 1 to 5, wherein the photonic crystal is formed by an fee or hcc lattice with a grid constant a, and wherein d = a / n0.5 with n = 1 to 20, in particular 1 to 5, is, and wherein n is (h^z + k² + I²) with h, k, and 1 as Miller indices.

7. The security and/or valuable document according to one of claims 1 to 6, wherein the lattice points of the photonic crystal are configured by means of spheres or the centers thereof .

8. The security and/or valuable document according to one of claims 1 to 7, wherein the spheres are coremantle particles,

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-27which are arranged in a close-packing of spheres.

9. The security and/or valuable document according to claim 8, wherein the mean diameter of the spheres is in the range

5 from 270 to 5,000 nm, in particular from 270 to 2,500 nm, if the luminescent substance emits in the IR range (780 to 3,000 nm)or wherein the mean diameter of the spheres is in the range from 135 to 1,200 nm, in particular from 135 to 600 nm, if the luminescent substance emits in the visible range (380 to 780

10 nm) or wherein the mean diameter of the spheres is in the range from 35 to 600 nm, in particular from 35 to 300 nm, if the luminescent substance emits in the UV range (100 to 380 nm).

10. The security and/or valuable document according to one of

15 claims 8 to 9, wherein the core-mantle particles comprise a core of an organic or inorganic core material and a mantle of a polymeric organic mantle material, the mantle material being flowable at an increased temperature, however the core material not being flow-able at the increased temperature.

11. The security and/or valuable document according to claim 10, wherein the organic core material is selected from the group comprising aliphatic, aliphatic/aromatic or fully aromatic polyesters, polyamides, polycarbonates, polyurea,

25 polyurethanes, aminoplast resins, phenoplast resins, such as for instance formaldehyde condensates of melamine, urea or phenol, epoxide resins, acrylesters, such as methyl (meth)acrylate, butyl (meth)acrylate, isopropyl (meth)acrylate, polystyrene, PVC, polyacrylnitrile, random or block

30 copolymerisates of one or several such homopolymers, and mixtures of two or more such different homopolymers or copolymers or wherein the inorganic core material is selected

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-28 from the group comprising metals, semimetals, metal chalcogenides, in particular metal oxides, metal pnictides, in particular metal nitrides or metal phosphides, and mixtures of two or more such different substances, wherein the metal can be

5 formed of an element of the first three main groups of the periodic table or of a metallic element of the side groups and wherein the semimetal may comprise Si, Ge, As, Sb, and Bi, is in particular selected from the group comprising SiO₂, TiO₂, ZrO₂, SnO₂ and A1₂O₃ .

12. The security and/or valuable document according to claim 10 or 11, wherein the core material has a glass temperature in the range of more than 60 °C, preferably more than 80 °C, most preferably more than 90 °C, or wherein the core material has a

15 glass temperature of more than 300 °C.

13. The security and/or valuable document according to one of claims 10 to 12, wherein the mantle material is selected from the group comprising aliphatic, aliphatic/aromatic or fully

20 aromatic polyesters, polyamides, polycarbonates, polyurea, polyurethanes, aminoplast resins, phenoplast resins, as for instance formaldehyde condensates of melamine, urea or phenol, epoxide resins, polyepoxides, poly(meth)acrylate, such as polymethyl (meth)acrylate, polybutyl (meth)acrylate,

25 polyisopropyl (meth)acrylate, polystyrene, PVC, polyacrylnitrile, polyethylene, polypropylene, polyethylene oxide, polybutadiene, polytetrafluorethylene, polyoxymethylene, caoutchouc, polyisoprene, random or block copolymerisates of one or several such homopolymers, and mixtures of two or more

30 such different homopolymers or copolymers, and wherein the mantle material has a glass temperature in the range from 40 to 90 °C, in particular from 60 to 80 °C, or in the range from 80

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-292016225899 07 Dec 2017 to 250 °C.

14. The security and/or valuable document according to one of claims 1 to 13, wherein the luminescent substance is arranged

5 in the photonic crystal or in the particles of the photonic crystal, in particular in the core material and/or in the mantle material of the coremantle particles or wherein the luminescent substance is arranged between the particles of the photonic crystal or wherein the photonic crystal is underlaid

10 with the luminescent substance.

15. A method for producing a security and/or valuable document or a security element according to one of claims 1 to 14, wherein the substrate is provided on a surface or partial

15 surface with a coating comprising the particles of the photonic crystal to be formed, and this coating is condensed under simultaneous exposure to heat and pressure, optionally before coating with the particles of the photonic crystal, a luminescent layer comprising the luminescent substance being

20 applied to the substrate, and/or the particles of the photonic crystal comprising the luminescent substance or being mixed therewith.

16. The method according to claim 15, wherein the exposure to

25 heat takes place with a temperature in the range from 60 to

180°C, in particular from 70 to 130 °C, and for a time from 0.5 to 7,200 s, preferably from 0.5 to 3,600 s, most preferably from 1 to 10 s or wherein the condensation is performed with a pressure from 1 to 100 bars, preferably from 1 to 20 bars or

30 wherein the condensation is achieved by means of a press, in particular a lamination press or wherein on the coating with particles of the photonic crystal, a separation and/or

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-30protection layer is arranged or wherein the protection layer is welded during the exposure to heat and pressure to the substrate, if applicable to the luminescent layer, and to the layer with particles of the photonic crystal or is laminated so

5 to form a layer system or wherein the protection layer is transparent, referred to the emission wavelength lambda.

18. A security and/or valuable document or security element obtainable with a method according to one of claims 15 to 17.

19. The security and/or valuable document according to one of claims 1 to 14 or 18 in the embodiment as an identity card, passport, access allowance card, visa, control symbol, ticket, driver license, vehicle document, banknote, cheque, postage

15 stamp, credit card, chip card or adhesive label.

20. A method for verifying a security and/or valuable document or a security element according to one of claims 1 to 14 or 18 to 19, including:

20 applying excitation energy to the luminescent substance so as to excite the emission of a luminescence radiation, the intensity of the luminescence radiation being observed or determined in dependence on the angle with respect to the surface of the security and/or valuable document;

25 modifying a relative angular orientation of the security element whereby to observe or determine an angular dependency of the emitted luminescence radiation; and verifying the security element on the basis of the observed or determined angular dependencies.

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