EP2033026A2 - Security element - Google Patents
Security elementInfo
- Publication number
- EP2033026A2 EP2033026A2 EP07725526A EP07725526A EP2033026A2 EP 2033026 A2 EP2033026 A2 EP 2033026A2 EP 07725526 A EP07725526 A EP 07725526A EP 07725526 A EP07725526 A EP 07725526A EP 2033026 A2 EP2033026 A2 EP 2033026A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- layer
- alignment layer
- motif
- security element
- crystalline material
- Prior art date
- 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.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 claims abstract description 18
- 239000002178 crystalline material Substances 0.000 claims description 39
- 230000003098 cholesteric effect Effects 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 19
- 230000005855 radiation Effects 0.000 claims description 19
- 239000000126 substance Substances 0.000 claims description 18
- 238000004132 cross linking Methods 0.000 claims description 14
- 238000007699 photoisomerization reaction Methods 0.000 claims description 14
- 239000007788 liquid Substances 0.000 claims description 13
- 238000006317 isomerization reaction Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 239000004988 Nematic liquid crystal Substances 0.000 claims description 10
- 239000012298 atmosphere Substances 0.000 claims description 7
- 230000000694 effects Effects 0.000 claims description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 230000000873 masking effect Effects 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 238000010894 electron beam technology Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 2
- 239000001569 carbon dioxide Substances 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 claims description 2
- 230000001747 exhibiting effect Effects 0.000 claims 1
- 239000004986 Cholesteric liquid crystals (ChLC) Substances 0.000 abstract description 21
- 239000004973 liquid crystal related substance Substances 0.000 abstract description 17
- 239000000463 material Substances 0.000 abstract description 16
- 238000006116 polymerization reaction Methods 0.000 description 10
- 238000007639 printing Methods 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 238000001035 drying Methods 0.000 description 4
- 239000011888 foil Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- 238000004049 embossing Methods 0.000 description 3
- 241001589086 Bellapiscis medius Species 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- 239000000049 pigment Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920002799 BoPET Polymers 0.000 description 1
- 238000003854 Surface Print Methods 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010017 direct printing Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000012447 hatching Effects 0.000 description 1
- 239000004920 heat-sealing lacquer Substances 0.000 description 1
- 238000012432 intermediate storage Methods 0.000 description 1
- 239000004922 lacquer Substances 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 239000002052 molecular layer Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920000139 polyethylene terephthalate Polymers 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000008521 reorganization Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 238000009281 ultraviolet germicidal irradiation Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
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
-
- 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
- B42D25/364—Liquid crystals
-
- 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
- B42D25/369—Magnetised or magnetisable materials
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/003—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using security elements
-
- B42D2033/26—
-
- B42D2033/30—
-
- B42D2035/20—
Definitions
- the invention relates to a security element for security papers, documents of value and the like having a carrier film which is provided at least in a partial region with an alignment layer having a substantially negligible optical effect, and with an aligned on the alignment layer, aligned motif layer based on a liquid crystalline material which has at least two areas forming a motif with different orientation of the liquid-crystalline material.
- Valuables such as branded goods or value documents, are often provided with security elements for safeguarding purposes, which allow a check on the authenticity of the object of value and at the same time serve as protection against unauthorized reproduction.
- security elements for safeguarding purposes, which allow a check on the authenticity of the object of value and at the same time serve as protection against unauthorized reproduction.
- the special properties of liquid-crystalline materials are exploited, and above all the viewing angle-dependent color impression and the light-polarizing effect of the liquid crystals.
- the liquid-crystalline material is usually applied to a suitable for the alignment of liquid crystals carrier film made of plastic.
- the carrier sheet may also be provided with a special alignment layer for aligning liquid crystals.
- Suitable alignment layers are, for example, a layer of a linear photopolymer, a finely structured layer or a layer oriented by the application of shear forces. Suitable finely structured layers can be produced by embossing, etching, scoring or direct printing of the structures.
- the document EP 1 336 874 A2 discloses a process for producing anisotropic polymer films with an improved alignment of polymerizable, for example nematic or cholesteric liquid-crystalline material on a substrate having a structured surface which is in the form of lattices. The direction of the grids can be chosen freely, so that patterned structures can be created.
- the photoaligment of liquid crystal layers is also known.
- alignment layers of linear photopolymers are used, which can be patterned by exposure to polarized light.
- document EP 0611 981 A1 describes an optical component having an anisotropic film of crosslinked liquid-crystalline monomers with locally different orientation of the liquid-crystal molecules, which has an alignment layer made of a photo-orientable polymer network in contact with the liquid crystal layer.
- the alignment layer is produced by selective irradiation with polarized UV light and the induced structure is fixed by crosslinking.
- the present invention seeks to provide a security element of the type mentioned, which avoids the disadvantages of the prior art.
- the security element provide improved alignment of liquid crystalline material and provide high protection against counterfeiting.
- the alignment layer is formed from a cholesteric liquid crystalline material, and the layer thickness of the alignment layer is chosen so that its optical effect is substantially negligible, and that
- the different orientation of the motif layer areas is effected by a different effective height of the helical structure of the semiconductor liquid crystal material of the alignment layer.
- the different effective height of the helical structure determines the preferred direction of the cholesteric liquid-crystalline material (indicated by the so-called "director") at the end of the helical structure facing away from the carrier film, ie at the surface of the alignment layer.
- the alignment layer and / or the motif layer are preferably printed during the production of the security element. After application and a possible solvent drying step, the alignment layer and / or the motif layer are crosslinked by UV radiation or by electron beam. Before crosslinking, the alignment layer may still be subjected to a photoisomerization step, as explained below.
- the different effective height of the helical structure of the cholesteric liquid crystal material of the alignment layer is produced by regions with differently sized layer thicknesses.
- the preferred direction of the cholesteric liquid crystal material changes within a pitch of 360 °. Therefore, on the surface of differently thick portions of the cholesteric alignment layer, the director generally points in various directions adjustable by the layer thickness.
- a subsequently applied nematic motif layer arranges with its preferred direction according to the respective specifications by the alignment layer.
- the preferred direction of the liquid crystals is in most cases in the layer plane.
- the invention also includes designs in which the preferred direction is slightly inclined to the horizontal.
- a layer with a photoisomerizable substance is applied to the carrier film as an alignment layer.
- a photo-isomerizable twisting agent can be advantageously used.
- the photoisomerizable twister may form the alignment layer together with a nematic liquid crystal system.
- the photoisomerizable reducer may be used in addition to a non-isomerized - O -
- the photoisomerizable and non-photoisomerizable twisters used may differ in terms of their effectiveness (indicated by the so-called HTP (helical twisting power) value) and / or their concentration.
- HTP helical twisting power
- concentration concentration
- the isomerization of the additional twisting device can lead to a change in the HTP value of this twisting device and thus result in a different pitch.
- the additional twisting device in the non-isomerized state can produce a different direction of rotation than the non-photoisomerizable twisting device.
- the carrier film with the applied alignment layer is exposed to partial UV radiation in order to isomerize the photoisomerizable substance in these partial regions.
- the photoisomerization of the liquid crystal material usually causes an increase in the pitch of the resulting cholesteric helical structure.
- the layer thickness of the alignment layer is therefore advantageously chosen so that it corresponds to the maximum desired rotation of the director of the cholesteric liquid crystals before the photoisomerization.
- the pitch of the helical structure in the exposed portions may be increased and the local twist of the director at the surface of the alignment layer may be reduced accordingly.
- the UV exposure to isomerization is advantageously carried out in an oxygen-containing atmosphere, in particular in air, so that the polymerization is initially prevented by the oxygen inhibition.
- the UV exposure to crosslinking then takes place in an inert gas Atmosphere, especially in an argon, nitrogen or carbon dioxide atmosphere.
- UV exposure to isomerization may also be in a wavelength range that does not cause cross-linking of the alignment layer. This can be achieved, for example, by suitably tuning the photoinitiator for the polymerization and the photoisomerizable substance.
- Narrow-band exposure for example with a UV laser, a UV LED or narrow-band filters outside the absorption band of the photoinitiator, initially triggers only the photoisomerization, but not the polymerization. Subsequently, the obtained structure can be fixed by the polymerization step.
- the UV exposure to the isomerization is preferably carried out through a mask, which shields the radiation causing the isomerization in the impermeable areas.
- the orientation layer is subjected to selective heating in regions before or during crosslinking, for example by means of a heat transfer roller provided with motifs or by means of a laser recorder, whereby it is also possible to achieve a regional change in the pitch of the helical structure.
- the motif layer of the security element is advantageously formed on the basis of a nematic liquid-crystalline material.
- the layer thickness of the motif layer can be uniform and lies in particular between about 0.5 and about 4 microns.
- the motif layer can be applied over the whole area to the alignment layer, since the motif is already predetermined by the different orientation of the alignment layer and taken over by the motif layer.
- the motif layer can additionally be applied to the alignment layer in the form of a second motif.
- the second motif can then be supplemented with the first motif formed by the differently oriented regions of the motif layer to form a total information.
- the alignment layer is preferably formed by combining a nematic liquid crystal system with a twist. According to the invention, it is always applied in such a layer thickness that its optical effect within the security element is negligible, and the optical effect is determined essentially only by the optical properties of the motif layer.
- the layer thickness of the security element is preferably always chosen smaller than the 5-fold pitch of the helical structure of the cholesteric liquid crystal material, since above this thickness already clearly recognizable color effects can occur.
- the layer thickness of the alignment layer is even smaller than twice the pitch of the helical structure of the cholesteric liquid crystal material.
- such thin cholesteric liquid-crystal layers also have the advantage that they can be produced reproducibly and with good accuracy, so that the orientation of the liquid crystal, which is decisive for the orientation, is also important. Talle on the surface of the alignment layer can be reproduced and specified exactly.
- one or more further layers can be provided which serve to protect the security element or one of its partial layers, to improve the adhesion of individual layers or to further increase the security against counterfeiting.
- the at least one further layer may, in particular, be a reflective layer, a diffraction-optically effective layer, such as a hologram, a color-tip-exhibiting layer, such as a further layer of cholesteric liquid-crystalline material, an interference layer, or a layer formed by iridescent interference-layer pigments or liquid-crystal pigments , or be a machine-readable layer.
- Such a machine-readable layer advantageously contains machine-readable feature substances, in particular reflective, magnetic, electrically conductive, phosphorescent, fluorescent or other luminescent substances.
- the invention also includes a method for producing a security element for security papers, value documents and the like, in which
- a carrier foil is provided and provided at least in a partial area with an alignment layer having a substantially negligible optical effect
- an aligned motif layer is applied based on a liquid-crystalline material having at least two forming a motif areas with different orientation of the liquid-crystalline material, wherein is applied as an alignment layer, a layer of a cholesteric liquid crystalline material in such a layer thickness that the optical effect of the alignment layer is substantially negligible, and wherein
- the different orientation of the motif layer areas is effected by a different effective height of the helical structure of the cholesteric liquid crystal material of the alignment layer.
- the invention further contains a security paper for the production of value documents or the like and a data carrier, in particular a value document, such as a banknote, identity card or the like, wherein the security paper or the data carrier according to the invention are equipped with a security element of the type described above.
- the described manufacturing method can be advantageously carried out on a conventional printing press, so that no separate machine for aligning the liquid crystals is required. Also, no polarized UV radiation is needed for alignment. Overall, a targeted alignment of nematic liquid-crystalline material is possible, which can be produced by printing thin alignment layers very fine structures.
- FIG. 1 is a schematic representation of a banknote with a security element according to the invention
- Fig. 2 shows a security element according to an embodiment of the
- FIG. 3 shows plan views of the security element of FIG. 2, showing (a) the visual impression without aids and (b) and (c) the impression when viewed with a linear polarizer placed in different orientations, FIG.
- Fig. 4 in (a) a security element according to another embodiment of the invention in cross-section, and in (b) a plan view of the security element of (a) when viewed with superimposed linear polarizer, and
- FIG. 5 in (c) a security element according to a further embodiment of the invention, and in (a) and (b) intermediate steps in the production of the security element of (c).
- Fig. 1 shows a schematic representation of a banknote 10, which is provided with a security element 12 according to the invention.
- the security element 12 appears structureless when viewed without aids. Only when a polarizing filter is placed on the banknote becomes, appears for the viewer a preselected motive, which allows him an assessment of the authenticity of the bill.
- a security element 20 has a carrier foil 22, for example a smooth PET foil of good surface quality, to which a thin alignment layer 24 made of a cholesteric liquid-crystalline material is applied, preferably printed.
- the imprint can be done for example in gravure, inkjet or flexographic printing.
- the alignment layer 24 is in the form of the desired motif in different subregions 26, 28 with different sized layer thickness or d 2 printed.
- both layer thicknesses di and d 2 lie below twice the pitch h of the helical structure of the cholesteric liquid crystal material.
- the pitch h of the cholesteric liquid crystal material is typically a few hundred nm.
- Cholesteric liquid crystal layers with a layer thickness in the range or below 2 times the pitch h can be reproduced and with good accuracy.
- the different orientation ⁇ of the director on the surfaces of the regions 26 and 28 can therefore be specified as desired.
- a comparatively thick motif layer 30 of nematic liquid-crystalline material is printed on the thus structured alignment layer 24 .
- the layer thickness of the motif layer 30 is typically substantially greater than the layer thicknesses of the alignment layer 24 and is for example 0.5 to 4 ⁇ m.
- the motif layer 30 can also be printed over the entire surface with a uniform layer thickness.
- the cholesteric liquid crystals of the alignment layer 24 serve to align the nematic liquid crystals of the motif layer 30.
- the liquid crystals of the nemate layer 30 always align themselves with their preferred direction so that their director points in the direction of the director of the surface of the underlying alignment layer 24.
- the different orientations of the director on the surface of the subregions 26, 28 of the alignment layer 24 thus produce a different orientation of the nematic liquid crystals in the subregions 32 and 34 of the motif layer 30, as indicated by the different hatching in FIG.
- the motif of the alignment layer formed by the subregions 26, 28 thus continues into the motif layer 30, resulting in a structured retarder with a regionally different orientation in accordance with the specifications of the motif of the alignment layer.
- the optical effect of the cholesteric alignment layer 24 can be neglected due to its low layer thicknesses di, 02 ⁇ h. typical In fact, in the case of cholesteric liquid crystal layers, a layer thickness of the order of magnitude of 10 * h, ie ten times the pitch, is required in order to achieve a distinct color-shift effect.
- the layer thickness of the alignment layer 24 is therefore chosen smaller than this layer thickness in the context of the invention, preferably even significantly smaller and more preferably below twice the pitch h, as in the exemplary embodiment described above.
- the optical effect of the security element 20 is then determined only by the differently oriented regions of the motif layer 30, while the alignment layer 24 does not contribute to the optical effect, but merely serves for the correct alignment of the nematic layer 30.
- the orientation difference ⁇ of the partial regions 32, 34 of 90 ° provides maximum contrast between light and dark in the exemplary embodiment.
- the linear polarizer 36 can be oriented so that it is maximally transparent to light from the partial areas 32, while blocking light from the partial areas 34 (FIG. 3 (b)).
- the linear polarizer 36 rotates through 90 °, the situation reverses and the polarizer blocks light from the subregions 32 while it is reading light from the subregions 34, as shown in FIG. 3 (c).
- an orientation difference ⁇ of 45 ° proves to be advantageous in order to achieve a maximum difference in contrast.
- the alignment layer 24 does not need to be fully applied in the invention. In the regions in which the alignment layer 24 has recesses or even larger gaps, the orientation of the motif layer 30 is then determined by an orientation predetermined by the carrier film 22 or by a separate alignment layer on the carrier film 22. The same effect can be achieved by a very thinly applied region of the alignment layer 24, since the preferred direction of a very thin cholesteric liquid crystal layer practically corresponds to the preferred direction of the underlying carrier film or an alignment layer, for example from a photoorientierbaren polymer network.
- the motif layer 30 can be applied over the whole area to the alignment layer 24, since a first motif is already predetermined by the structure of the alignment layer 24.
- the motif layer 30 but also applied in the form of a second motif, which is then superimposed and / or supplemented with the first motif of the alignment layer 24.
- the alignment layer 44 may be applied in the form of narrow parallel strips 46, 48 of different layer thickness and the motif layer 50 printed on the alignment layer 44 in the form of a coat of arms or any other graphic motif become.
- first motif alternating stripes of different brightness
- second motif coat of arms
- the alignment layer 24 or 44 is advantageously printed on the carrier film 22.
- the cholesteric liquid crystals of the alignment layer can be obtained in a manner known per se from nematic liquid crystals by adding small amounts of a twisting agent. After drying the solvent, the alignment layer is crosslinked by means of UV radiation or electron beam. Subsequently, or after an intermediate storage of the coated carrier films, a layer of nematic liquid crystals is printed. These orient themselves, as described, at the orientation of the uppermost molecular layer of the alignment layer, so that the Nematen layer can orient locally differently even with full-surface printing and therefore reproduce a desired motif.
- hologram embossing lacquer can be applied and a Holograinm Weggung (UV or thermal) take place.
- a direct metallization the application of heat sealing lacquer and subsequent application to a value document come into question, as well as the combination with other cholesteric liquid crystal structures and the transfer to a thread structure, for example for a security thread embedded in a security paper.
- the different orientation of the motif layer is produced by selective photoisomerization of a photoisomerizable substance in the alignment layer.
- a thin alignment layer 64 of a cholesteric liquid-crystalline material having a uniform layer thickness d is first applied to a smooth PET film 62 of good surface quality, as shown in FIG. 5 (a).
- the alignment layer is preferably printed. Optionally, it is dried physically or by a thermal dryer after printing.
- the alignment layer 64 in this variant of the invention contains a photoisomerizable substance which isomerizes on exposure and thereby alters the pitch of the resulting helical structure of the cholesteric liquid crystal material.
- the photoisomerizable substance may be a photoisomerizable twisting agent whose twisting strength changes upon exposure.
- the alignment layer 64 is exposed in a further step in air to a desired subject with UV radiation 66, as shown in Fig. 5 (b).
- the exposure effects in the irradiated portion 68 a photoisomerization of the cholesteric liquid crystal material and thus usually an increase in the pitch of the helical structure.
- the layer thickness d of the alignment layer 64 is therefore chosen in the exemplary embodiment so that it corresponds to the maximum desired rotation of the director of the cholesteric liquid crystals. If the pitch of the helix structure in the exposed portions 68 is increased by local exposure and photoisomerization, the twist of the director on the surface of the alignment layer 64 is thereby reduced.
- the exposure can be done by a mask 70, for example with a flashlamp as a radiation source.
- a rotating mask for example, a rotating, equipped with motifs transparent cylinder, such as quartz or plastic, comes into question.
- the cylinder can be arranged both above the moving web and under the moving web. In the latter case, wrapping of the web with full contact is possible, but the carrier film 62 must be transparent in the UV range used for the isomerization. In the case of a mask cylinder arranged above the web, this requirement does not apply to the carrier film 62, but there is a risk that the contact of the cylinder with the web disturbs the layer.
- the exposure can also be done by a mask already printed on the back of the film.
- the film must be transparent to the UV radiation used.
- the latter method may require the transfer of the layer at the latest at the end of the production process, should the mask motif not appear in the final product.
- the motif can also be applied with a removable printing ink, which after exposure removed from the carrier film 62, z. B. washed off, is. It is also conceivable, the motive of the mask by a UV-absorbing and visually unrecognizable ink to produce. A mask provided with such a print can therefore remain on the carrier film.
- the exposure can be effected by a masking tape guided parallel to the carrier film 62, as described in the publication DE 10330421 A1.
- the exposure can be done with both the positive image and the negative image of the desired subject.
- the mask 70 used may be absorbent or reflective, in which case the heating of the mask or foil may be minimized. It is understood that only the radiation leading to isomerization must be shielded from the mask.
- the printed and exposed carrier film advantageously passes through a heated zone with low turbulence so that the alignment layer will not be faded.
- a motif layer 72 of nematic liquid crystals can be printed on the alignment layer 64 over the entire surface or in the form of another motif.
- the nematic liquid crystals arrange with their preferred direction according to the specifications of the alignment layer 64, so that motif areas 74 and 76 with different orientation of the nematic liquid crystals are formed, as shown in FIG. 5 (c).
- the detection of the motif can be done by means of a linear polarizer, as in the embodiments described above.
- the photoisomerization of the first step can be effected by using a narrow band radiation source, such as a laser source, UV LEDs, or conventional radiators in conjunction with narrow band filters, without causing polymerization by the radiation lying outside the absorption band of the photoinitiator.
- a narrow band radiation source such as a laser source, UV LEDs, or conventional radiators in conjunction with narrow band filters
- the photoisomerization can also take place before the solvent drying, so that only a heated dryer section is required.
- the crosslinking of the alignment layer 64 then takes place after passing through the solvent dryer.
Landscapes
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Polarising Elements (AREA)
- Credit Cards Or The Like (AREA)
- Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)
- Bidet-Like Cleaning Device And Other Flush Toilet Accessories (AREA)
- Burglar Alarm Systems (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102006027236A DE102006027236A1 (en) | 2006-06-09 | 2006-06-09 | security element |
PCT/EP2007/004629 WO2007140887A2 (en) | 2006-06-09 | 2007-05-24 | Security element |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2033026A2 true EP2033026A2 (en) | 2009-03-11 |
EP2033026B1 EP2033026B1 (en) | 2010-09-29 |
Family
ID=38663840
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP07725526A Active EP2033026B1 (en) | 2006-06-09 | 2007-05-24 | Security element |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP2033026B1 (en) |
AT (1) | ATE483176T1 (en) |
DE (2) | DE102006027236A1 (en) |
WO (1) | WO2007140887A2 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102007022437A1 (en) * | 2007-05-10 | 2008-11-13 | Leonhard Kurz Gmbh & Co. Kg | Process for producing a crosslinked liquid-crystal layer and device for carrying out the process |
DE102008061608A1 (en) | 2008-12-11 | 2010-06-17 | Giesecke & Devrient Gmbh | security element |
DE102010019766A1 (en) * | 2010-05-07 | 2011-11-10 | Giesecke & Devrient Gmbh | Method for producing a microstructure on a support |
DE102011114750A1 (en) * | 2011-09-29 | 2013-04-04 | Giesecke & Devrient Gmbh | Process for producing a microstructure support |
DE102017003795A1 (en) | 2017-04-19 | 2018-10-25 | Giesecke+Devrient Currency Technology Gmbh | Polymeric value document substrate, security element, value document and manufacturing method |
FR3105088B1 (en) * | 2019-12-20 | 2021-12-24 | Oberthur Fiduciaire Sas | Optical structure with relief effect |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1120737A1 (en) * | 2000-01-27 | 2001-08-01 | Rolic AG | Optical security device |
JP2002127647A (en) * | 2000-10-19 | 2002-05-08 | Nhk Spring Co Ltd | Discriminating medium of object and manufacturing method thereof |
CA2498417A1 (en) * | 2002-09-11 | 2004-03-25 | Robert Hammond-Smith | Birefringent marking |
DE102004021247A1 (en) * | 2004-04-30 | 2005-11-24 | Giesecke & Devrient Gmbh | Security element and method for its production |
-
2006
- 2006-06-09 DE DE102006027236A patent/DE102006027236A1/en not_active Withdrawn
-
2007
- 2007-05-24 WO PCT/EP2007/004629 patent/WO2007140887A2/en active Application Filing
- 2007-05-24 EP EP07725526A patent/EP2033026B1/en active Active
- 2007-05-24 DE DE502007005217T patent/DE502007005217D1/en active Active
- 2007-05-24 AT AT07725526T patent/ATE483176T1/en active
Non-Patent Citations (1)
Title |
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See references of WO2007140887A2 * |
Also Published As
Publication number | Publication date |
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EP2033026B1 (en) | 2010-09-29 |
WO2007140887A3 (en) | 2008-03-27 |
DE502007005217D1 (en) | 2010-11-11 |
DE102006027236A1 (en) | 2007-12-13 |
WO2007140887A2 (en) | 2007-12-13 |
ATE483176T1 (en) | 2010-10-15 |
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