WO2019119039A1 - Procédé et système de fabrication d'un film de sécurité - Google Patents

Procédé et système de fabrication d'un film de sécurité Download PDF

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Publication number
WO2019119039A1
WO2019119039A1 PCT/AU2018/051360 AU2018051360W WO2019119039A1 WO 2019119039 A1 WO2019119039 A1 WO 2019119039A1 AU 2018051360 W AU2018051360 W AU 2018051360W WO 2019119039 A1 WO2019119039 A1 WO 2019119039A1
Authority
WO
WIPO (PCT)
Prior art keywords
heat
foil
process according
activated adhesive
coating
Prior art date
Application number
PCT/AU2018/051360
Other languages
English (en)
Inventor
Gary Fairless Power
Original Assignee
Ccl Secure Pty Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from AU2017905154A external-priority patent/AU2017905154A0/en
Application filed by Ccl Secure Pty Ltd filed Critical Ccl Secure Pty Ltd
Publication of WO2019119039A1 publication Critical patent/WO2019119039A1/fr

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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/20—Layered products comprising a layer of metal comprising aluminium or copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F16/00—Transfer printing apparatus
    • B41F16/0006—Transfer printing apparatus for printing from an inked or preprinted foil or band
    • B41F16/004—Presses of the reciprocating type
    • B41F16/0046—Presses of the reciprocating type with means for applying print under heat and pressure, e.g. using heat activable adhesive
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B32B15/085—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising polyolefins
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    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/12—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of paper or cardboard
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    • B32B23/04—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B23/042—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of metal
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    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • 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
    • B42D25/351—Translucent or partly translucent parts, e.g. windows
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • 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
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    • B42D25/30—Identification or security features, e.g. for preventing forgery
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    • 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
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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • 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
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    • B42D25/455—Associating two or more layers using heat
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    • B42D25/40—Manufacture
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    • B42D25/45—Associating two or more layers
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    • B42D25/47—Associating two or more layers using chemicals or adhesives using adhesives
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    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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Definitions

  • the present invention relates to methods for producing a security film, and in particular to methods which include providing a polymeric film substrate having a heat-activated adhesive coating, providing a foil, and pressing the foil onto the polymeric film substrate with a heated surface so as to heat-activate the adhesive and adhere the foil to the substrate.
  • the invention also relates to security films produced according to the process of the invention, to security documents comprising these security films, and to systems for producing the security films.
  • Polymeric films are increasingly being used as substrates in fields where security, authentication, identification and anti-counterfeiting are important.
  • Polymer- based products in such areas include, for example, bank notes, credit cards, important documents (e.g. ID materials including passports and land title, share and educational certificates), films for packaging high-value goods for anti-counterfeiting purposes, security labels and security cards.
  • Polymeric films have advantages in terms of security, functionality, durability, cost-effectiveness, cleanliness, processability and environmental considerations. Arguably the most notable amongst these is the security advantage.
  • Paper-based bank notes for example, can be relatively easy to copy, and there is higher occurrence of counterfeit bank notes in countries with paper-based bank notes compared to those countries using polymer-based bank notes.
  • polymer- based bank notes are longer-lasting and less-easily torn than their paper-based counterparts.
  • Security documents based on polymeric films have the advantage that the high temperatures used in copying machines will often cause melting or distortion of polymer base materials if counterfeiters attempt simply to copy security documents (e.g. bank notes) using such machines.
  • security documents based on polymeric films are amenable to the incorporation of a variety of visible and hidden security features. Since the introduction of the first polymer bank notes, security features have included optically variable devices (OVDs), opacification features, printed security features, security threads, embossing, transparent windows and diffraction gratings.
  • ODDs optically variable devices
  • OVDs include holograms, diffraction grating images and/or liquid crystal technology, for example.
  • OVDs may exhibit various optical effects, such as movement or colour changes, according to the viewing angle.
  • a major advantage of OVDs is that they cannot be accurately replicated or reproduced without using expensive, specialist equipment - simply photocopying or scanning the OVD will not work.
  • a foil for application to a substrate generally consists of a multi-layer laminate structure on a carrier film.
  • the laminate structure may include a layer bearing a relief structure designed to create an optically variable effect, typically formed by embossing and curing a lacquer coating.
  • the laminate structure may also, or alternatively, comprise a metallised layer, for example comprising copper or aluminium, which enhances an optical effect of the foil.
  • the hot stamping foil includes a sizing layer comprising a heat-activated adhesive, optionally together with one or more additives.
  • the hot stamping foil is typically supplied in roll format, and is unwound from the roll during the application process.
  • the hot stamping foil and the polymeric surface are then brought into proximity, and a heated die is applied to the foil from the side of the release film to stamp the foil onto the substrate.
  • the die is applied at a temperature and pressure, and for a time, sufficient to transfer heat across the foil and heat-activate the adhesive, thereby allowing the adhesive to flow and create a strong adhesive bond between the foil and the substrate over the required dimensions of the security feature.
  • the carrier film is removed, leaving the foil security feature irreversibly adhered to the substrate.
  • the foil stamping process requires a considerable application of heat in the region of the substrate where the adhesive bond is to be formed: if the heat load applied to the foil is too low, a poor adhesive bond results. In many cases, an adjacent region of the polymeric surface is also exposed to high temperatures, without an intervening layer of foil to adsorb the heat.
  • the polymeric film substrate is typically a thermoplastic material itself, so that application of heat to the substrate beneath and adjacent to the foil at an unduly high temperature will result in undesirable dimensional change.
  • a foil may be adhered to polymeric film substrates, including those with low surface energy surfaces such as polyolefins, by providing a coating comprising a first heat-activated adhesive on the substrate, and subsequently pressing the foil onto the substrate with a heated tool so as to heat- activate the adhesive.
  • the new adhesive bond created during the foil application process is thus established between the foil and a heat-activated adhesive coating already present on the polymeric substrate, rather than between a heat-activated foil sizing layer and the polymeric surface of the substrate, as is conventional.
  • the potentially challenging adhesion between the polymeric surface and the heat-activated adhesive can be created in an independently controlled coating process using conditions not readily compatible with foil application processes.
  • the potential advantages of this approach are improved aesthetics of adhered foils, lower thermal stress placed on the polymeric substrate, improved capacity in high throughput foil-adhesion processes, for example web-processing manufacturing, and the mitigation or elimination of foil blocking in the unwind roll.
  • the invention provides a process for producing a security film, the process comprising: providing a polymeric film substrate having a coating comprising a first heat-activated adhesive; providing a foil; and pressing the foil onto the polymeric film substrate with a heated surface so as to heat- activate at least a portion of the first heat-activated adhesive, thereby adhering the foil to the polymeric film substrate.
  • a“security film” means a film provided with one or more security features which is, or may be further processed to become, any type of security document of value or identification document including, but not limited to the following: items of currency such as bank notes and coins, credit cards, cheques, passports, identity cards, securities and share certificates, driver's licences, deeds of title, travel documents such as airline and train tickets, entrance cards and tickets, birth, death and marriage certificates, and academic transcripts.
  • items of currency such as bank notes and coins, credit cards, cheques, passports, identity cards, securities and share certificates, driver's licences, deeds of title
  • travel documents such as airline and train tickets, entrance cards and tickets, birth, death and marriage certificates, and academic transcripts.
  • a“heat-activated adhesive” is an adhesive composition, comprising one or more components, which transforms under influence of elevated temperatures, i.e. via a glass transition or melt, into a sufficiently fluid state to permit the formation of an adhesive bond with another material upon subsequent cooling.
  • the first heat-activated adhesive is heat-activated at an application temperature of between about 50°C and about 150°C, preferably between about 70°C and about 1 10°C.
  • the application temperature is the temperature of the coating produced by the transfer of heat from the heated surface when pressing the foil onto the polymeric film substrate. It will be appreciated that the application temperature should be sufficiently high to adequately heat-activate the first heat-activated adhesive, yet not be high enough to cause irreversible dimensional or other undesirable changes in the underlying polymeric film substrate or the foil layers through which the heat is transmitted. Therefore, a suitable application temperature will depend on the properties of the materials involved.
  • providing the polymeric film substrate having the coating comprises applying a coating composition comprising the first heat-activated adhesive to the polymeric film substrate.
  • the coating composition may be applied by any suitable technique in the art, including a method selected from gravure printing, reverse roll printing, and die coating.
  • the coating composition further comprises a solvent or carrier fluid in which at least the first heat-activated adhesive is dissolved or dispersed. The coating may then be produced by drying the coating composition on the substrate to remove at least a portion of the solvent or carrier fluid.
  • the polymeric film substrate may comprise a core film and a primer layer to improve the adhesion between the coating and the substrate.
  • the primer layer may comprise cross-linked polyethyleneimine.
  • the process may thus further comprise applying a primer composition to a core film prior to applying the coating composition.
  • the primer composition may include a primer polymer such as polyethyleneimine and optionally a cross-linking agent.
  • the coating may have a substantially constant thickness, at least over the area where the foil is to be adhered to the substrate.
  • the coating may be less than 5 microns in thickness, such as between about 1 micron and about 3 microns.
  • the foil comprises a sizing layer comprising a second heat-activated adhesive.
  • pressing the foil onto the polymeric film substrate with the heated surface heat-activates at least a portion of each of the first and the second heat-activated adhesives, and induces commingling thereof in at least an interlayer between the foil sizing layer and the substrate coating.
  • the application temperature should be sufficiently high to adequately heat-activate both adhesives.
  • the commingled adhesives solidify together to create a strong adhesive bond via the interlayer.
  • the first and second heat-activated adhesives generally comprise first and second thermoplastic base polymers respectively.
  • a thermoplastic base polymer is a primary polymer component of a heat-activated adhesive that undergoes a heat-induced phase transformation, such as glass transition and/or crystalline melting, which allows the adhesive to fluidise when heat-activated.
  • the first and the second thermoplastic base polymers have a Hansen distance (R a ) of below 3 MPa 1/2 , or below 2 MPa 1/2 , preferably below 1 MPa 1/2 .
  • the Hansen distance is a thermodynamic parameter used in the art to estimate and predict the compatibility of molecules, including polymers, taking into account the dispersion, polar and hydrogen bonding interactions. More chemically similar polymers generally have lower Hansen distances. It is believed that the mobilised polymer chains of first and second thermoplastic base polymers having a low Hansen distance are able to better able to intermingle and entangle when the first and second heat-activated adhesives are heat-activated, thereby providing a strong adhesive bond.
  • the first and the second thermoplastic base polymers are polymers of the same one or more monomers.
  • the first and the second thermoplastic base polymers comprise the same one or more monomers in substantially the same proportions.
  • the first thermoplastic base polymer is substantially identical to (i.e. any differences are no more than expected due to normal variations in the production methodology), or the same polymer as, the second thermoplastic base polymer. In the limiting case where the first and second thermoplastic base polymers are the same, the Hansen distance is zero.
  • the first thermoplastic base polymer and the second thermoplastic base polymer may be a polymer or co-polymer of acrylate or vinyl ester monomers, for example one selected from the group consisting of an acrylate polymer, an ethylene- acrylate co-polymer, a vinyl acetate polymer, an ethylene-vinyl acetate co-polymer, and an acrylate-vinyl acetate co-polymer.
  • the first heat-activated adhesive has a glass transition temperature that is within 10°C, preferably within 5°C, most preferably within 2°C of a glass transition temperature of the second heat-activated adhesive.
  • the first heat-activated adhesive has a crystalline melting temperature that is within 10°C, preferably within 5°C, most preferably within 2°C of a crystalline melting temperature of the second heat-activated adhesive. Similar glass transition or melting temperatures (depending on the nature of the adhesive) will result in substantially simultaneous fluidisation of the first and second heat-activated adhesives during the foil application process, thereby facilitating the commingling of the adhesives.
  • the first and second heat-activated adhesives may comprise other components compounded with the thermoplastic base polymers, and which are generally also at least partially fluidised during heat-activation.
  • the first heat-activated adhesive and/or the second heat-activated adhesive further comprise an anti-blocking wax additive, which may optionally be selected from the group consisting of carnauba, poly(tetrafluoroethylene) wax, polyethylene wax and Fischer-Tropsch wax.
  • the wax additive has a melting temperature below, and preferably at least 30°C below, the application temperature.
  • the first heat-activated adhesive is substantially identical to (i.e. any differences are no more than expected due to normal variations in the production methodology), or the same as the second heat-activated adhesive.
  • the coating and the sizing layer may each have a substantially constant thickness, at least over the area where the foil is to be adhered to the substrate.
  • Each of the coating and the sizing layer may be less than 5 microns in thickness, such as between about 1 micron and about 3 microns. In some embodiments the combined thickness of the coating and the sizing layer may be less than 5 microns, such as between 2 and 4 microns.
  • providing the foil having the sizing layer comprises applying a sizing composition comprising the second heat-activated adhesive to a layer of the foil.
  • the sizing composition may be applied by any suitable technique in the art, including a method selected from gravure printing, reverse roll printing, and die coating.
  • the sizing composition further comprises a solvent or carrier fluid in which at least the second heat-activated adhesive is dissolved or dispersed.
  • the sizing layer may then be produced by drying the sizing composition on the layer to remove at least a portion of the solvent or carrier fluid.
  • the sizing composition is the same as the coating composition applied to the polymeric film substrate.
  • the heated surface is a hot-stamping die.
  • the foil is thus hot-stamped onto the polymeric film substrate with a hot stamping press.
  • other methods of foil application may be employed, including continuous stripe application, where the heated surface may be a heated roller.
  • the polymeric film substrate comprises a polyolefin, preferably biaxially oriented polypropylene.
  • the foil comprises a metallic layer, optionally comprising copper or aluminium.
  • the foil comprises an optically variable device, which may comprise a diffractive structures formed in an embossed and cured coating layer in the foil.
  • the foil may be a security foil and/or a decorative foil for use on a security document.
  • the invention provides a security film produced by a process according to any of the embodiments disclosed herein.
  • the invention provides a security document comprising a security film according to the second aspect.
  • the invention provides a system comprising: a polymeric film substrate having a coating comprising a first heat-activated adhesive; a foil; and a press comprising a heatable surface configured to press the foil onto the polymeric film substrate so as to heat-activate at least a portion of the first heat-activated adhesive.
  • the foil comprises a sizing layer comprising a second heat-activated adhesive.
  • the press is a hot stamping press, for example a vertical press, and the heatable surface is a hot-stamping die.
  • the terms“first” and“second” in relation to various features of the disclosed methods or systems are arbitrarily assigned and are merely intended to differentiate between two such features that are incorporated in various embodiments. The terms do not of themselves indicate any particular orientation or sequence, nor do they imply any compositional or other differences between such features. Moreover, it is to be understood that the presence of a“first” feature does not imply that a“second” feature is present, and vice versa.
  • Figure 1 schematically depicts in side view a foil hot stamping system according to an embodiment of the invention.
  • Figure 2 schematically depicts in side view a foil and a polymeric substrate with a coating comprising a heat-activated adhesive, positioned in the system of Figure 1 for hot stamping a foil security feature onto the substrate according to an embodiment of the invention.
  • Figure 3 schematically depicts in side view the foil and polymeric substrate of Figure 2 with the heated die pressing the foil onto the substrate against a backing plate.
  • Figure 4 schematically depicts in side view the polymeric substrate of Figure
  • Figure 5 schematically depicts in side view a foil with a sizing layer and a polymeric substrate with a coating comprising a heat-activated adhesive, positioned in the system of Figure 1 for hot stamping a foil security feature onto the substrate according to another embodiment of the invention.
  • Figure 6 depicts a web manufacturing system including both a coating unit operation for applying a coating composition comprising heat-activated adhesive to a polymeric substrate and the foil hot stamping system depicted in Figure 1 .
  • the present invention relates to a process for producing a security film.
  • the process comprises providing a polymeric film substrate having a coating comprising a first heat-activated adhesive, and a foil.
  • the foil is then pressed onto the polymeric film substrate with a heated surface so as to heat-activate at least a portion of the first heat- activated adhesive.
  • the foil is thereby adhered to the polymeric film substrate.
  • the polymeric film substrate may generally be any suitable polymeric substrate for security documents.
  • the substrate may comprise a synthetic plastic or polymeric material including but not limited to a polyolefin, a polystyrene, a polyvinyl chloride, a polycarbonate, a polyester such as polyethylene terephthalate (PET), a polyamide, an acetate; or a composite material of two or more materials, such as a laminate of paper and at least one polymeric material, or of two or more polymeric materials.
  • the polymeric film substrate may comprise a biopolymer, for example cellulose or derivatives thereof, carbohydrate-based polymers or lactic acid based polymers e.g. polylactic acid.
  • the polymeric film substrate may comprise a polyolefin, for example polyethylene, polypropylene, polybutylene, mixtures, blends or copolymers (random or block) thereof and/or other known polyolefins.
  • a particularly suitable substrate for security documents such as bank notes is polypropylene, and in particular bi-axially oriented polypropylene.
  • the polymeric film substrate may be a mono-layer film, or it may be a multi layer film. In the latter case, the film may comprise at least one core film forming a substantial element of the substrate’s overall thickness.
  • the multi-layer film may comprise one or more additional layers such as skin layers, coatings, co-extrudates, overlacquers and the like.
  • the core film and any skin layers or coatings may independently be formed of any of the suitable polymeric materials disclosed herein.
  • the skin layers and/or coatings may have a thickness of from about 0.05 pm to about 5 pm, from about 0.1 pm to about 3 pm, from about 0.2 pm to about 2 pm or from about 0.3 pm to about 1 pm.
  • the polymeric film substrate, or core film thereof may made by any process known in the art, including, but not limited to, cast sheet, cast film and blown film.
  • the film may be prepared as a balanced film using substantially equal machine direction (MD) and transverse direction (TD) stretch ratios, or can be unbalanced, where the film is significantly more oriented in one direction (MD or TD).
  • Sequential stretching can be used, in which heated rollers effect stretching of the film in the machine direction and a stenter oven is thereafter used to effect stretching in the transverse direction.
  • simultaneous stretching for example, using the so-called bubble process, or simultaneous draw stenter stretching may be used.
  • the polymeric film substrate may be mono-oriented in either the machine or transverse directions.
  • the polymeric film substrate may be biaxially oriented.
  • the total thickness of the polymeric film substrate may vary depending on the requirements of the security document.
  • the polymeric film substrate may have a thickness of from any one of 1 pm, 5 pm, 10 pm, 15 pm, 20 pm or 30 pm; to any one of 50 miti, 70 miti, 80 miti, 100 miti, 120 miti, 200 miti or 350 miti.
  • polymeric film substrates of from 60 to 100 pm thick, preferably from 65 to 90 pm thick may be particularly suitable.
  • an intermediate layer disposed between the core film and the coating comprising the first heat-activated adhesive.
  • the intermediate layer may be a primer layer to improve the adhesion between these substrate and the coating, such as a layer comprising polyethyleneimine.
  • the polyethyleneimine primer layer may also include a cross- linking agent, for example a multi-functional isocyanate, which cross-links and thus cures the polyethyleneimine layer on the substrate.
  • a cross- linking agent for example a multi-functional isocyanate
  • primers suitable for use in the invention include: hydroxyl terminated polymers; hydroxyl terminated polyester based co-polymers; cross-linked or uncross-linked hydroxylated acrylates; polyurethanes; and UV curing anionic or cationic acrylates.
  • suitable cross-linkers include: isocyanates; polyaziridines; zirconium complexes; aluminium acetylacetone; melamines; and carbodi-imides.
  • the primer layer is generally a very thin layer, for example of less than 1 micron thickness. Furthermore, the primer layer once formed on the substrate generally does not undergo heat-induced phase transformations (such as glass transitions, crystalline melting or softening) at typical foil application temperatures. Typically, this is because the primer layer is cross-linked, and thus not susceptible to heat-activation into a fluid state.
  • heat-induced phase transformations such as glass transitions, crystalline melting or softening
  • the polymeric surface of the polymeric film substrate may also be advantageous to modify the polymeric surface of the polymeric film substrate to improve the adhesion of the coating comprising the first heat-activated adhesive.
  • the polymeric surface may therefore be modified according to methods previously disclosed in the art, including via plasma treatment, corona discharge treatment, modified atmosphere dielectic barrier discharge treatment or flame treatment. Such treatments may optionally be applied to disrupt the surface crystallinity and to produce polar functionalities on low surface energy polymeric surfaces, including polyolefins.
  • the polymeric film substrate is substantially or entirely free from migratory additives.
  • 'migratory additives' mean those additives which have a tendency to migrate to the surface of a film, causing surface contamination.
  • Migratory additives may include one or more of slip promoting additives, anti-static additives, anti-block additives and plasticisers, for example erucamide, calcium stearate and glycerol monostearate.
  • Migratory additives such as those mentioned above are often added to polymeric film substrates to make handling of the film easier.
  • the use of migratory additives in polymeric film substrates has several drawbacks when the film forms part of a laminate structure. For example the accumulation of migratory additives at the polymeric film surface, before or after application of a foil, may affect the adhesion and appearance of the adhesive layers or the foil itself. Additionally, the optical properties of the film may be adversely affected.
  • the polymeric film substrate is a transparent or translucent polymeric material, which permits the inclusion of a number of security devices relying on the transmission of light.
  • a transparent area or "window" One common security feature in polymeric banknotes produced for Australia and other countries is a transparent area or "window".
  • the polymeric film substrate to which the foil is adhered is (or is to become) a window region of a security document.
  • the substrate may then include one or more opacifying layers over other regions of the substrate surface.
  • the polymeric film substrate may be an insert into a cut-out region of a substantially opaque material, such as paper or fibrous material.
  • the polymeric film substrate may comprise, prior to foil adhesion according to the invention, one or more of a large number of other security devices, elements or features intended to protect the security document against counterfeiting, copying, alteration or tampering.
  • Security features may take a wide variety of forms, such as security threads embedded in layers of the security document; security inks such as fluorescent, luminescent and phosphorescent inks, metallic inks, iridescent inks, photochromic, thermochromic, hydrochromic or piezochromic inks; printed and embossed features, including relief structures; interference layers; liquid crystal devices; lenses and lenticular structures; optically variable devices (OVDs) such as diffractive devices including diffraction gratings, holograms and diffractive optical elements (DOEs).
  • ODDs optically variable devices
  • DOEs diffractive optical elements
  • a wide variety of foils may be provided in accordance with the invention, including hot stamping foils.
  • the foil is typically, prior to use in the process, a laminate structure comprising a carrier film and at least some of the following layers: a release coating, a colour coating, an embossed (three-dimensionally structured) coating, a metallic layer and a cover layer.
  • the carrier film may be a polyester film, for example a polyethylene terephthalate film of about 10-20 microns thickness.
  • the release coating is generally a wax which facilitates the facile release of the carrier film from the remainder of the foil, once adhered to the substrate.
  • various optically variable devices may be formed from optionally metallised diffractive structures formed in an embossed and cured coating.
  • Such coatings may be prepared by embossing and simultaneously curing an acrylic based UV-curable clear lacquer, such as can be obtained from various manufacturers including Kingfisher Ink Limited, product ultraviolet type UVF-203 or similar.
  • the OVD may be, for example, a hologram, a diffraction grating image or comprise liquid crystal technology.
  • the OVD may comprise iridescent images, which exhibit various optical effects, for example movement or colour changes, according to the viewing angle.
  • the metallic layer may be a metal foil layer as commonly understood in the art, i.e. a thin sheet of metal usually formed by hammering or rolling a piece of metal.
  • the metallic layer may a metallised layer formed, for example, by vacuum metallisation. Vacuum metallised coatings may be particularly preferred for metallising embossed structures in a foil.
  • the metallic layer may in some embodiments comprise copper or aluminium.
  • the polymeric film substrate has a coating which comprises a first heat- activated adhesive, as will be described in greater detail hereafter.
  • the coating is generally of substantially constant thickness over at least the portion of substrate intended to receive the foil.
  • the coating thickness is typically less than about 5 microns, such as between about 1 micron and about 3 microns. It will be appreciated that the preferred thickness of the coating may depend on whether a sizing layer is present on the foil to be applied, and the thickness of that layer. Where a foil with a relatively thicker sizing layer is provided, a relatively thinner coating on the polymeric film substrate may be preferred, such that the combined adhesion layer formed after foil application remains of a suitable dimension.
  • the coating may consist only of the first heat-activated adhesive.
  • the sizing layer may further comprise one or more solid additives, for example inorganic particulates such as titanium dioxide. Such non-melting particulates may facilitate the outwards escape of air from between the polymeric substrate and the foil during the application process.
  • the coating is generally applied onto the laminate foil structure as a liquid coating composition, either as a melt of the heat-activated adhesive or as a solution or dispersion of the heat-activated adhesive in an aqueous or organic solvent or carrier fluid. Any non-melting particulate additives are dispersed in the liquid composition when applied.
  • the coating composition may be applied at the desired thickness by methods including gravure printing, reverse roll printing, and die coating.
  • the solidified coating is then formed by drying and/or cooling the liquid coating composition.
  • the coating composition comprises a solvent in which the heat activated adhesive is dissolved
  • the coating composition may optionally be dried at an elevated temperature, for example above a glass transition temperature or a crystalline melting temperature of the first heat-activated adhesive. Without wishing to be bound by any theory, it is believed that this may produce a favourably homogeneous coating and/or improve the adhesion of the coating to the polymeric film substrate.
  • the foil has a sizing layer (also known as an adherence layer) comprising a second heat-activated adhesive, as will be described in greater detail hereafter.
  • the composition of the sizing layer may be similar to, or the same as, that of the coating on the substrate, for example including the same heat activated adhesive composition and any solid additives dispersed therein.
  • inorganic particulate additives may aid in preventing the sizing layer from blocking while the foil is in roll format during storage or processing.
  • the sizing layer is generally of substantially constant thickness over the portion of foil intended to be adhered to the polymeric film substrate.
  • the sizing layer thickness is typically less than about 5 microns, such as between about 1 micron and about 3 microns.
  • the sizing layer may be applied onto the laminate foil structure as a liquid sizing composition, as described herein for the coating composition applied to the polymeric film substrate.
  • Providing the foil according to the process of the invention may thus include forming the sizing layer on the foil.
  • a commercially available foil already having a suitable sizing layer may be utilised in the process of the invention.
  • the coating on the polymeric film substrate and the sizing layer on the foil comprise a heat-activated adhesive (i.e. the first and second heat-activated adhesives, respectively).
  • Suitable heat-activated adhesives may be substantially amorphous thermoplastic materials with a glass transition temperature (T g ) above 0°C, and generally above 60°C.
  • the heat-activated adhesives may be semi crystalline or crystalline thermoplastic materials which do not exhibit a clear T g above room temperature, but which have a crystalline melting point above about 60°C.
  • heat-activation of the adhesive at a temperature below that which causes irreversible dimensional or other undesirable changes in the polymeric film substrate or the foil layers, results in sufficient plasticity to allow an adhesive bond to be formed between the foil and the substrate when the adhesive subsequently cools.
  • the heat activation induces commingling and polymeric chain entanglement between the two adhesives in least an interlayer between the coating and the sizing layer.
  • the heat-activated adhesives generally comprise a thermoplastic base polymer.
  • Any suitable thermoplastic base polymers may be used, including those previously disclosed for use in foil adhesion layers.
  • the base polymer may be a polymer or co-polymer of acrylate or vinyl ester monomers.
  • the thermoplastic base polymer may comprise one or more of an acrylate (acrylic) polymer, an ethylene-acrylate co-polymer (such as ethylene-n-butyl acrylate and ethylene- acrylic acid co-polymers), a vinyl acetate polymer, including partially hydrolysed poly(vinyl acetate), an ethylene-vinyl acetate co-polymer, an acrylate-vinyl acetate co polymer.
  • thermoplastic base polymers for a given application will depend particularly on the nature of the polymeric film substrate, since it is important that a strong adhesion is produced between the substrate surface and its adhesive coating.
  • the heat-activated adhesives may further comprise other components compounded with the thermoplastic base polymers, which are generally also at least partially fluidised during heat-activation.
  • these components may include anti-blocking wax additives, such as carnauba, poly(tetrafluoroethylene) wax, polyethylene wax or Fischer-Tropsch wax, which generally have a melting point below, and preferably at least 30°C below, the intended temperature of heat-activation.
  • the wax additive may be included in the adhesive to prevent unwanted blocking of the foil and/or the substrate during storage or roll-to-roll processing.
  • the heat-activated adhesives may comprise tackifiers, coupling agents, residual solvents from the adhesive coating composition or other additives.
  • the foil comprises a sizing layer comprising a second heat-activated adhesive, such that the coating and the sizing layer are adhered together in the process of the invention.
  • the first and the second heat- activated adhesive compositions may be the same or different.
  • the first and the second heat-activated adhesives are preferably similar or substantially the same, as this is believed to facilitate the commingling of the adhesives during the foil application process of the invention.
  • the adhesion between the first and second heat-activated adhesives relies at least in part on chain entanglements between the thermoplastic base polymers of the adhesives at an interlayer between the substrate coating and the foil sizing layer.
  • the first heat-activated adhesive comprises a first thermoplastic base polymer and the second heat-activated adhesive comprises a second thermoplastic base polymer
  • the first thermoplastic base polymer and the second thermoplastic base polymer may be polymers of the same one or more monomers, and preferably comprise the same one or more monomers in substantially the same proportions.
  • the first and second thermoplastic base polymers may also have similar molecular weights.
  • the first thermoplastic base polymer is substantially identical to, or the same as, the second thermoplastic base polymer.
  • Hansen solubility parameters may be a useful tool to select suitable first and second thermoplastic base polymers which are thermodynamically compatible for forming a strong adhesive bond between the first and second heat-activated adhesives.
  • Compatible polymers will generally have a low distance (R a ) in Hansen space, as calculated by equation (1 ):
  • d ⁇ A and d ⁇ B are the dispersion parameters for polymers A and B dR A and dR B are the polar parameters for polymers A and B
  • dH A and dH B are the hydrogen bonding parameters for polymers A and B
  • the dispersion, polar and hydrogen bonding parameters relate to the capacity of molecules to interact via dispersion forces (i.e. van der Waals interactions), via polar forces (i.e. dipole-dipole interactions) and via hydrogen bonding forces respectively. These parameters, generally expressed in units of MPa 1/2 , are known for a wide variety of polymers.
  • the polymer chains of first and second thermoplastic base polymer pairs having a relatively small Ra value will be able to intermingle when the polymers are in a viscous state due to their chemical compatibility.
  • the Ra value is below 5 MPa 1/2 , preferably below 3 MPa 1/2 , more preferably below 2 MPa 1/2 , such as below 1 MPa 1/2 .
  • R a is zero.
  • the first and second thermoplastic base polymers should have suitable chain lengths (generally correlated to molecular weights) to allow intermingling and also the subsequent entanglement needed to form a strong adhesive bond during heat-activation and pressure contact between the two adhesive layers.
  • Longer polymer chains with sufficient compatibility will generally be thermodynamically capable of the necessary entanglements for strong adhesion. However, they may be may be kinetically restricted from adequately intermingling during the foil adhesion process of the invention (such as hot-stamping).
  • Shorter chain polymers may be readily heat-activated and intermingled, but may be less capable of forming the necessary entanglements at the interlayer between the sizing layer and the coating to create a strong adhesive bond.
  • suitable molecular weights for a given combination of first and second thermoplastic base polymers may depend on the chemical nature of the polymers. The skilled person, with the benefit of this disclosure, will be able to determine suitable molecular weights for the thermoplastic base polymers with no more than routine experiments.
  • first and second thermoplastic base polymers Apart from the similarity (or ideally, the substantial identity) of the first and second thermoplastic base polymers, other components (if present) of the first and second heat-activated adhesives may also be similar, such that the first heat-activated adhesive is similar to, or the same as, the second heat-activated adhesive.
  • the coating on the substrate and the sizing layer on the foil have the same composition.
  • this approach is believed to provide the greatest degree of compatibility between the two adhesive layers, and thus the strongest adhesive bond, it may nevertheless be preferred in some embodiments that the coating on the substrate and the sizing layer on the foil are non-identical.
  • the coating applied to the polymeric film substrate is merely sufficiently similar in composition to the foil sizing layer.
  • it may have a suitably compatible but non-identical thermoplastic base polymer, or it may have the same thermoplastic base polymer, but be compounded with different additives.
  • the coating on the polymeric film substrate has a strong adhesive bond to the polymeric film surface. It is a potential advantage of the invention that the coating is applied to the polymeric film substrate prior to the foil adhesion step: the coating process can thus be independently controlled, for example via solvents, application temperatures, application times, drying procedures etc. This independent process control may facilitate the potentially challenging task of establishing a strong substrate- adhesive bond, particularly where low surface energy polymeric film substrates such as polyolefins are used. It may thus be preferred or necessary in some embodiments to tailor the composition of the first heat-activated adhesive for improved adhesion to the polymeric film substrate, even at the expense of partially reducing the compatibility between the first and second heat-activated adhesive compositions.
  • the first heat-activated adhesive may have a glass transition temperature that is within 10°C, preferably within 5°C, most preferably within 2°C of a glass transition temperature of the second heat-activated adhesive.
  • the first heat-activated adhesive has a crystalline melting temperature that is within 10°C, preferably within 5°C, most preferably within 2°C of a crystalline melting temperature of the second heat- activated adhesive.
  • the first and second heat-activated adhesives will be substantially simultaneously heat-activated during the foil application process.
  • the process of the invention comprises a step of pressing the foil onto the polymeric film substrate with a heated surface so as to heat-activate at least a portion of the first heat-activated adhesive, or both the first and second heat-activated adhesives (if a sizing layer is present on the foil).
  • the heat is transferred from the heated surface, through the layers of the foil, and thus into the coating and sizing layer.
  • the heat-activated adhesive has cooled after removing the heated surface, an adhesive bond is formed between the foil and the substrate which generally cannot be broken without irreversibly degrading the foil.
  • the foil may be pressed onto the substrate by a variety of methods available in the art, including hot stamping and continuous stripe application.
  • the foil is hot stamped onto the polymeric film substrate.
  • a heated die typically made of metal or silicone, is used to stamp the foil onto the substrate, typically against a backing surface.
  • the die may be configured with the dimensions of the foil structure to be applied to the substrate, and may optionally be structured to transfer a three-dimensional impression into the adhered foil.
  • continuous webs of the substrate and the foil are brought into proximity for hot-stamping via a roll- to-roll web manufacturing processing.
  • Hot stamping may be performed with a variety of hot-stamping presses, including vertical (up/down) presses.
  • Continuous stripe application may be performed with a continuous foil application machine having a heated roller.
  • the foil should be pressed onto the polymeric film substrate so as to produce an application temperature sufficient to heat-activate the heat-activated adhesive(s), but below the temperatures at which irreversible dimensional or other undesirable changes in the polymeric film substrate or the foil layers results.
  • the application temperature is between about 50°C and about 150°C, preferably between about 70°C and about 1 10°C.
  • the foil should also be pressed onto the polymeric film substrate at a sufficient pressure to produce a satisfactory adhesive bond, for example via commingling of the first and second heat-activated adhesives.
  • the foil is pressed onto the polymeric film substrate at a pressure of above about 1 .0 tons, for example above 1 .3 tons, such as between 1 .3 tons and 2.0 tons.
  • Sufficient dwell time i.e. the time of pressing the foil against the substrate, should be allowed to provide heat transfer from the die to the adhesive(s) via the laminate structure of the foil. Suitable dwell times will depend on variables including the die temperature, the heat transfer rate across the foil, and the nature and thickness of the adhesive layers.
  • the process typically also comprises a step of stripping away the carrier layer of the foil and optionally also surrounding areas of the laminate foil structure not adhered to the substrate.
  • a sufficient stripping time i.e. the time between removal of the heated surface and stripping away of the foil carrier layer, should be allowed to permit the heat-activated adhesive(s) to cool and harden, thus rendering the adhesive bond permanent. Insufficient stripping time may result in incomplete foil transfer or damage to the foil layers.
  • FIG. 1 depicts foil hot stamping system 100.
  • Biaxially-oriented polypropylene film substrate 101 in the form of a web, is fed using guide rollers 102 and 103 over backing plate 104.
  • Substrate 101 is selectively coated with coating 105, comprising a heat-activated adhesive as described herein, on part of one surface.
  • Coating 105 which has a thickness of approximately 3 microns and dimensions approximating the shape and size of the security feature to be adhered, may optionally be applied to substrate 101 at a print station ahead of the foil stamping system in the same web manufacturing operation, as will be described in greater detail hereafter.
  • Foil 106 is unwound from a feed roll and fed as a web through hot stamping system 100 using guide rollers 107 and 108. Foil 106 and substrate 101 are thus brought into close parallel proximity and positioned in register such that the intended security feature portion of the foil web will be hot stamped onto the intended receiving area of the substrate web coated with coating 105. Heated die 1 10 is positioned to press foil 106 onto substrate 101 against backing plate 104, in the direction shown by arrow 1 1 1.
  • foil 106 is a laminate structure comprising polyethylene terephthalate carrier film 1 15 and security feature layer 1 16, for example an embossed and metallised optically active layer.
  • a release coating (not shown) is provided between layers 1 15 and 1 16 to facilitate stripping of the carrier film from the security feature layer after hot stamping.
  • foil 106 lacks a sizing layer with heat-activated adhesive.
  • foil 106 and substrate 101 webs are fed into position in hot stamping system 100, heated die 1 10 presses foil 106 onto substrate 101 against backing plate 104, as depicted in Figure 3, and heat is transferred through the layers of foil 106 and into coating 105.
  • the die temperature, dwell time and stamping pressure are selected in accordance with the principles disclosed herein, and in particular to produce an hot stamping application temperature at coating 105 sufficient to fluidise its heat-activated adhesive, for example about 85-95°C. As a result, heat-activated coating 105 adheres to layer 1 16 of foil 106.
  • heated die 1 10 is withdrawn and heat-activated coating 105 rapidly cools and solidifies, thus rendering the bond between foil and substrate permanent.
  • carrier film 1 15 and non-adhered areas of layer 1 16 surrounding the hot- stamped region are stripped away, leaving the adhered security feature part of layer 1 16 on substrate 101 as depicted in Figure 4.
  • foil 106 further includes sizing layer 1 17.
  • Sizing layer 1 17 includes a heat-activated adhesive, which may be similar to or substantially identical to that of coating 105, according to the principles disclosed herein.
  • the thickness of coating 105 may be reduced such that the combined loading of heat-activated adhesive in coating 105 and sizing layer 1 17 in the hot-stamping area is similar to that of the embodiment depicted in Figure 2.
  • Sizing layer 1 17 may be present across the entire foil web, as depicted, or only over part of the foil, including the area to be transferred by hot stamping.
  • heated die 1 10 presses foil 106 onto substrate 101 against backing plate 104, and heat is transferred through the layers of foil 106 into both sizing layer 1 17 and coating 105.
  • the die temperature, dwell time and pressure are selected in accordance with the principles disclosed herein, and in particular to produce an hot stamping application temperature at sizing layer 1 17 and coating 105 sufficient to fluidise their respective heat-activated adhesives, for example about 85-95°C, and thus induce commingling thereof in at least an interlayer.
  • heated die 1 10 is withdrawn and the heat- activated adhesives of coating 105 and sizing layer 1 17 rapidly cool and solidify, thus rendering the bond between foil and substrate permanent.
  • Carrier film 1 15 and non- adhered areas of layer 1 16 are then stripped away, leaving the adhered security feature part of layer 1 1 6 on substrate 101 as also depicted in Figure 4.
  • Coating 105 may be applied to substrate 101 as an earlier unit operation in in the same web manufacturing operation where foil 106 is adhered.
  • Figure 6 depicts system 200 suitable for such an integrated operation.
  • Substrate 101 is unwound from unwind roll 201 and feed as a web through gravure print station 202, where a coating composition comprising heat-activated adhesive dissolved in solvent is selectively printed onto the substrate surface.
  • Substrate 101 may optionally include a thin cross- linked polyethyleneimine primer layer to facilitate adhesion of the coating, or may be subjected to a corona discharge treatment or other surface modification technique at an in-line unit operation (not shown) between unwind roll 201 and print station 202.
  • Substrate 101 is then fed past heater 203, which dries the coating composition at a temperature above the softening temperature of the heat-activated adhesive, thereby removing the solvent. Once cooled, homogeneous and smooth coating 105 is thus formed on substrate 101 , which is then fed through foil hot stamping system 100 as described herein. After the foil security feature adhesion, substrate 101 may be fed to rewind roll 203.
  • system 200 may include a wide variety of other unit operations, not shown in Figure 6, as required for the manufacture of security documents, including multiple print stations for the application of opacification layers and indicia, stations for the application of other security features, turner bars to turn the substrate over for operations on the other side, and the like.
  • Hot melt adhesive coatings of either 1 .5 pm or 3.0 pm thickness were prepared on the primed surface of a transparent, biaxially oriented polypropylene film substrate. This was done by applying a coating composition comprising a heat- activated adhesive (softening temperature 86°C) in a solvent, and removing the solvent at temperature above the softening temperature of the adhesive to produce a smooth, homogeneous adhesive coating.
  • a coating composition comprising a heat- activated adhesive (softening temperature 86°C) in a solvent, and removing the solvent at temperature above the softening temperature of the adhesive to produce a smooth, homogeneous adhesive coating.
  • Foils with sizing layers thus applied were then hot stamped onto the coated or uncoated polymeric substrates with an up/down hot stamping press. Different combinations of foils and polymeric substrates, and different hot stamping conditions, were investigated as indicated in Table 1 .

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Laminated Bodies (AREA)
  • Adhesives Or Adhesive Processes (AREA)

Abstract

L'invention concerne un procédé de fabrication d'un film de sécurité, le procédé consistant : à fournir un substrat de film polymère ayant un revêtement comprenant un premier adhésif activé par la chaleur ; à fournir une feuille ; et à presser la feuille sur le substrat de film polymère avec une surface chauffée de façon à activer thermiquement au moins une partie du premier adhésif activé par la chaleur, ce qui permet de faire adhérer la feuille au substrat de film polymère.
PCT/AU2018/051360 2017-12-22 2018-12-19 Procédé et système de fabrication d'un film de sécurité WO2019119039A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2017905154 2017-12-22
AU2017905154A AU2017905154A0 (en) 2017-12-22 Process and system for producing a security film

Publications (1)

Publication Number Publication Date
WO2019119039A1 true WO2019119039A1 (fr) 2019-06-27

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102020001666A1 (de) 2020-03-12 2021-09-16 Giesecke+Devrient Currency Technology Gmbh Folien-Sicherheitselement und Verfahren zur Herstellung eines Wertdokuments mit dem Folien-Sicherheitselement

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4536016A (en) * 1981-08-24 1985-08-20 Solomon David H Banknotes and the like
WO2016001807A1 (fr) * 2014-06-30 2016-01-07 Innovia Films Limited Procédé de production d'un film de sécurité et film de sécurité
WO2017072512A1 (fr) * 2015-10-30 2017-05-04 Innovia Films Limited Film pour billet de banque biréfringent

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4536016A (en) * 1981-08-24 1985-08-20 Solomon David H Banknotes and the like
WO2016001807A1 (fr) * 2014-06-30 2016-01-07 Innovia Films Limited Procédé de production d'un film de sécurité et film de sécurité
WO2017072512A1 (fr) * 2015-10-30 2017-05-04 Innovia Films Limited Film pour billet de banque biréfringent

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102020001666A1 (de) 2020-03-12 2021-09-16 Giesecke+Devrient Currency Technology Gmbh Folien-Sicherheitselement und Verfahren zur Herstellung eines Wertdokuments mit dem Folien-Sicherheitselement

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