EP3959081A1 - Film de sécurité robuste à décalage de couleur à valeurs spectrales complexes à large spectre et fil de sécurité fabriqué à partir de celui-ci - Google Patents

Film de sécurité robuste à décalage de couleur à valeurs spectrales complexes à large spectre et fil de sécurité fabriqué à partir de celui-ci

Info

Publication number
EP3959081A1
EP3959081A1 EP20727732.8A EP20727732A EP3959081A1 EP 3959081 A1 EP3959081 A1 EP 3959081A1 EP 20727732 A EP20727732 A EP 20727732A EP 3959081 A1 EP3959081 A1 EP 3959081A1
Authority
EP
European Patent Office
Prior art keywords
film
substrate
coating
liquid crystal
colour shift
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.)
Pending
Application number
EP20727732.8A
Other languages
German (de)
English (en)
Inventor
Shilpan Pravinchandra Patel
Rishil PATEL
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Arrow Greentech Ltd
Original Assignee
Arrow Greentech 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
Application filed by Arrow Greentech Ltd filed Critical Arrow Greentech Ltd
Publication of EP3959081A1 publication Critical patent/EP3959081A1/fr
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—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
    • B42D25/355—Security threads
    • 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
    • B42D25/40—Manufacture
    • B42D25/45—Associating two or more layers
    • B42D25/465—Associating two or more layers using chemicals or adhesives
    • B42D25/47—Associating two or more layers using chemicals or adhesives using adhesives

Definitions

  • the present invention relates to a cost effective, eco-friendly, high security film with enhanced spectrum wavelength and stable colour shift. More particularly the present invention discloses a high security colour shift film with more advanced way of making a high security film with colour shift effect that is far more stable and is more consistent its characteristics during the manufacturing process.
  • security film with colour shift visual effects give special security effects to a security threads, which are used for high secure materials such as banknotes, confidential paper, stamp paper and other application are made from conventional process which affects the quality and characteristics of the colour shift film due to repetition of process.
  • the supply source of key raw materials also add to the security element, like in this case the LC and certain coatings are key raw materials.
  • the prior art has inherent problems, like the colour shift elements, being fragile, failing certain tests, like crumpling tests and rub tests, which is much required for long term useage during currency in circulation, and tend to give a“false positive” as far as security is concerned.
  • This may be seem to happen, leading to the bond between the base film and the colour shift liquid crystals, like case, of certain prior art as mentioned in patent WO-A-03061980 or other inorganic particles (in case of vacuum metallization), as disclosed in Patent W02005038136A, being apolar chemicals, tend to get“unstuck” from the carrier PET film as these particles or coatings are fragile micro particles, but are responsible for the colour shifting effect, due to light interference, as explained in these disclosures -
  • Patent US 8603615B2 teaches about use of various inorganic particles being deposited on a carrier film.
  • US 8603615B2 teaches the complexities of stacks, using inorganic materials like Tin Oxide, Silicon Oxide, etc, which reflect a different set of colours. Finding a combination which display a precise colour shift spectral value, and in particular a wide spectrum colour shift values, is very complex, never attempted by anyone in prior art, and an expensive operation, which may not be commercially viable, and therefore our invention teaches the wide spectrum colour shift values, using LC Films and combination thereof.
  • Liquid crystal materials can be incorporated into security devices either as a film, as for example in WO-A-03061980, or in the form of an ink as a liquid crystal in an organic binder, as for example in EP-A- 1156934.
  • the advantage of a liquid crystal ink is that it can be applied using conventional gravure or roll to roll printing processes and therefore it is relatively straightforward to apply the liquid crystal material in the form of a design.
  • the colour shift spectral value consistency, brightness and sharpness of the observed colour and colour-shift are significantly degraded for a liquid crystal ink compared to a liquid crystal film, as disclosed in our invention. This degradation is due to the variability in alignment of the cholesteric helical axis between the individual liquid crystals compared to the uniform alignment of the liquid crystal film.
  • Our invention protects the colourshift values and properties, by disclosing a robust colourshift film which displays consistent spectral values throughout the circulation life of the bank note, and laminating this unique LC film onto the main “receiver” substrate, which may be mettalised, demetalised, opaque/black printed or otherwise treated to display the desired colourshift spectral values.
  • our invention discloses incorporating a tie coat onto the “receiver” substrate, which may be mettalised, demetalised, opaque/black printed or otherwise treated to display the desired colourshift spectral values and overcoating the same with a lacquer coating, having high gloss, scratch resistant, sebum resistant, dirt resistant and UV protective property.
  • This coating may be engineered as per the specification of the end user, and is by no way to be a limitation.
  • our invention also discloses a robust overcoat, like but not limited to, a clear, UV curable lacquer to be used to protect the robustness of the colour shift qualities.
  • This process includes a lacquer coating, having high gloss, scratch resistant, sebum resistant, dirt resistant and protection from long range nanometer (as found in daily sunlight) UV light.
  • This coating may be engineered as per the specification of the end user, and is by no way to be a limitation.
  • Yet another way of making the security threads is to print/coat a web of clear film, preferably polyester film, with a specific colour shift ink/coating medium, on a metalized/de-metalized, optionally opaque printed/coated.
  • a web of clear film preferably polyester film
  • a specific colour shift ink/coating medium preferably organic chemistry
  • the primary object of this invention relates to a robust, cost effective, eco- friendly, high security film with enhanced spectrum wavelength and stable colour shift.
  • Another objective of the present invention there is to provide a more complex, secure and an improved security film that displays a wider spectrum of colour shift effect like, but not limited to, Blue (450nm +/- 15 nm) to Red (700 nm +/- 15 nm) that is more difficult to replicate, thus creating a very secure currency note.
  • Another objective of the present invention is to provide an improved security film that is nearly transparent, clear to look at, but once overlaid on a dark/opaque substrate/indicia/text then it displays pre-defined set of colour, with precise spectral values having a complex colour spectrum when viewed at certain angles.
  • Yet another objective of the present invention there is to provide an improved security film that is far more stable and does not change its characteristics during the manufacturing process.
  • Yet another objective of the present invention there is to provide an improved security film that is far more stable and does not change its colour shift properties during the paper making process and retains it’s characteristics for a longer period of time during circulation.
  • Yet another objective of the present invention is to provide an improved security film that once bonded or laminated to a metalized, de-metalized, black ink printed/coated substrate, will give the wide spectrum colour shift effect, in a pre designed spectrum, consistently and till the end of effective life of the currency note.
  • Yet another object of the present invention is to provide an improved security film using Tie coat process which enables the security thread manufacturer to use the step of lamination of liquid crystal film based carrier film to receptor film which may be mettallised/demettalised and/or dark/opaque coated/printed substrate, without the process of detaching the LC film carrier .
  • the tie coated carrier film creates a robust structure and protects the fragile LC Polymers from detaching during the process of security thread manufacturing, insertion into security paper or during currency in circulation.
  • Yet another objective of the present invention is to provide an improved security film that helps to maintain the desired properties of Liquid crystal film, in a pre defined spectrum values, consistently and till the end of effective life of the currency note , by avoiding an over lamination film using using a robust laquer, as a protective layer .
  • Yet another objectve of the present invention is to provide a method of manufacturing an improved security film that discloses a more complex and wide spectrum colour shift film using a novel method of manufacturing liquid crystal film.
  • the present invention discloses a high security wide spectrum colour shift film and a method of manufacturing a high security film with wide spectrum colour shift effect that is far more stable and does not change its characteristics during the manufacturing process.
  • the present invention provides an improved security film using Tie coat process which enables the step of lamination of liquid crystal to receptor mettalised/de- mettalised and/or dark/opaque coated/printed substrate, without the process of detaching the Liquid Crystal film carrier.
  • the present invention discloses an improved high security colour shift film with added features, having a robust tie coat that is more economical than a film laminate, it provides protection against sebum and dirt.
  • the improved high security colour shift film has longer shelf life in long term external use and also withstand several mechanical stress and strain, thereby compensates for the brittle/cracking nature of liquid crystal film.
  • the present invention discloses construction of high security colour shift film as described by the present invention.
  • the object of the present invention is to introduces a new, improved, eco-friendly, high secure and complex film, which is nearly transparent, clear to look at, and optionally, will display a pre-defined set of spectral values when tilted at specific angles.
  • a Highly secure and complex Colour shift film comprising of at least two different liquid crystal layer wherein the colour shift film exhibits colour shift effect over a wider spectrum/wavelength and wherein, at least one of the Liquid crystal film is adhered/ bonded to a metalized, de-metalized, black ink printed/coated polar substrate through a tie coat layer and the two Liquid crystals are bonded through an adhesive layer.
  • Fig. 1 illustrates a basic construction of liquid crystal‘A’ film defined as LC Film Roll 1 in the present invention.
  • Fig. 2 illustrates a basic construction of liquid crystal ⁇ ’ film defined as LC FilmRoll 2 in the present invention.
  • Fig. 3 illustrates another embodiment of high security wide spectrum colour shift film formed by combining roll 1 and roll 2 herein defined as wide spectrum tie adhered LC Film Roll 3 in the present invention.
  • Fig. 4a illustrates high security wide spectrum colour shift film anddetaching the liner in the present invention. This process may be done during or before production of security thread operation,
  • Fig. 4b illustrates another embodiment of construction of high security wide spectrum colour shift film adhering through tie coat on PET substrate in the present invention. This process may be done during or before production of security thread operation,
  • Fig. 5a illustrates a basic construction of robust security thread with a cast & cure top lacquer as disclosed in the present invention. This process may be done during production of security thread operation.
  • Fig. 5b illustrates a basic construction of robust security thread using the tie coat process as disclosed in the present invention.
  • the present invention provides an improved high security colour shift film with a robust top coating, which is more economical than a film laminate, has higher/controlled gloss versus reflected light as also provides protection against sebum and dirt, to ensure longer life to the security features even in long term external use and against severe mechanical stress and strain.
  • the high security colour shift film of the present invention compensates for the brittle nature of LCs (Liquid Crystals) and also provides better protection against many daily chemicals, such as those found in cleaning and washing.
  • the high security colour shift film of the present invention is the most secure and durable security thread for insertion in bank note paper, including insertion in highly alkaline pulp slurry, under wet conditions.
  • LC Means liquid crystal polymers, that can be chiral, nematic/cholesteric or combination thereof and has a specific wavelength
  • LC Film means LC film formed after casting/coating/printing and subsequently drying and curing. LC film is formed on a support film, which is typically a clear, dimensionally stable PET film;
  • Carrier Film means a film, like but not limited to, PET film, PP film, PC film and like;
  • PET Film made from Polyethylene terephthalate resin BOPET film ranging from 3 microns to 36 microns, preferably 6 microns to 24 microns, more preferably from 9 microns to 12 microns
  • Tie coat also known as anchor coat, is coated onto a film (in this case PET film), for better adhesion of apolar resins/inks/coatings/polymer (LC) to form a bond between polar PET to apolar polymeric resin, eg. LC polymer, for the purpose of this invention. Tie coat also ensures that the bond between PET film and LC becomes one unified bond upon curing the whole construction;
  • a film in this case PET film
  • LC apolar resins/inks/coatings/polymer
  • Opaque Printing is defined to cover, any kind of metallic, non-metallic, carbon ink based, titanium oxide based inks etc.
  • the opacity and dark properties of printing ink is of relevance, while the minerals or metals or other inorganic materials used to make ink, is not a limiting factor.
  • dark black background is found to be showing the best colour shift properties;
  • Tie II Coat for this invention, means flash cured tie coatis defined as an adhesive between layers of LCs or layers of PET films and LC or layers of LC Or coated films or any kind of coatings.
  • This tie coat may have characteristics like that of PSA (pressure sensitive adhesives) or non PSA and may be a formulation of resins, one or more like, Polyvinyl alcohol, polymides derivatives or other polymers, which include acrylics, nylons, UV curable Acrylates, polyurethanes or combination thereof.
  • the curing process may be done by using hot air or LED or UV.
  • the solvents may be water, toluene’s, xylenes, Kenotic or family of Cyclohexanone. The combination and list of polymers, resins and organic materials and solvents are not limited.
  • Receptor Film means the “receiving” film. For the purpose of this invention it relates to the black/dark printed/coated or metal printed or a de- mettalised film or indicia/text/graphic enhanced film, upon which the “donor” LC film is bonded to create the colour shift effects, at discreet areas;
  • Donor Film a clear, dimensionally stable carrier film, like but not limited to PET film, without a tie coat, which is“transfers” the LC film onto the “receiving” film, on the desired side of the“Receptor film” ;
  • Tie Coated Film a clear, dimensionally stable carrier film, like but not limited to PET film, with a specific tie coat, for effectively bonding between LC polymers, during the LC coating/printing process, ensuring effective wetting, prior to UV/LED curing, as well as effective bonding to “Receptor” film, during the Security Thread making process;
  • Tie Coated LC Film a clear, dimensionally stable carrier film, like but not limited to PET film, coated with a bond enhancing tie coat for boding a PET film having higher dyne values (range of 40-65), to an apolar LC polymer, during the LC coating/printing process, ensuring effective wetting, prior to UV/LED curing, as well as effective bonding to“Receptor” film, during the Security Thread making process;
  • Spectral Values are defined as values as measured using a spectrophotometer, like Carl Zeiss (as mentioned in the patent), and recording peaks and valleys of the wavelengths. The range of the visible values are as shown in Figure A. These values are given in nanometers (nm) and these nm values correspond to the colour spectrum of VIBGYOR.; NIR: means Near Invisible Red. This is the other end of the spectrum, which is not readily visible to eye, when light is reflected on it, like 750 nm and beyond;
  • NIV means Near Invisible Ultra Violet spectrum of the colour range, like 380 nm and under.
  • Liquid Crystal Film is a key film responsible for discreet colour shift values, is essentially clear at first instance, with a mild hue of colours, created by reflection of random light, at random angles, but when laminated to a Metalized, or de- metalized and/or opaque coated and/or opaque ink printed receptor film, forms a colour shift effect of pre-defined colour values, also known as“spectral values” and once slit into micro tapes, ends up as a high security thread.
  • Using a tie coated LC Film, as disclosed in the invention provides protection against sebum and dirt.
  • the improved security thread has longer shelf life in long term external use and also withstand several mechanical stress and strain.
  • UV fluorescent pigments may be added. After, insertion into paper, during the process of making bank note paper, it’s final end use is to secure currency/banknotes of various countries.
  • the present invention provides an improved, purpose engineered, eco-friendly and high secure and complex colour shift security film, which is nearly transparent, clear to look at, and optionally, after affixing to a darker background, when tilted it will display a pre-defined set of spectral values when tilted as specified angles.
  • This Visible spectrum is defined in nanometers as values.
  • the spectral values (as shown in figure‘A’) will define the visible colour to our eyes, and will change from gracing angle to tilted angle. Following visible spectrum (380nm to 750nm) will shed more light on the VIBGYOR in nanometers, which in turn will define the colour range of the spectrum.
  • Fig. A This complex LC Coated film is nearly clear to look at the first instance, but once it is bonded to an opaque substrate, like but not limited to a black printed/coated film, will show a pre specified colour shift effect, at specific angles, at the points where the opaque design or indicia are located.
  • the present invention provides an improved security film using Tie coat process which enables the step of lamination of liquid crystal film to receptor mettallised/demettalised and/or dark/opaque coated/printed substrate, without the process of detaching the LC film carrier
  • this security film will be to attain a particular set of colour shift within the reflected light phenomena, like but not limited to blue changing to green ( 470nm to 540 nm) on angle of light* or a wider range like Blue changing to Red (450nm to 700nm), which is a more wider colour change, in the spectrum of VIBGYOR Light.
  • This security film once bonded or laminated to a metalized, de- metalized, black ink printed/coated, Receptor substrate, will give the wider range of colour shift effect.
  • the angle of viewing, in relation to colour shift, is typically 35 degrees to 45 Degrees, from gracing view (plain layflat view Fig B).
  • Step 1 LC coated on PET - Colour shift BLUE (450nm) to UV
  • Step 2 LC coated on PET - NIR to Red (700 nm)
  • Step 3 Lamination of LC Lilms - Colour shift Blue to Red (450nm to 700nm)
  • Step 1 LC coated on PET - Colour shift Turquoise (490nm) to UV
  • Step 2 LC coated on PET - NIR to Red(700nm)
  • Step 3 Lamination of LC - Colour shift Turquoise to Red (490nm to 700nm)
  • This invention will find its end use in production of security tapes/thread, which is presently used in Bank Notes/currency notes.
  • the present application discloses ahigh secure and complex colour shift film comprising of at least two different liquid crystal layer wherein the colour shift film exhibits colour shift effect over a wider spectrum/wavelength and wherein, at least one of the Liquid crystal layer is adhered/ bonded to apurpose engineered“receptor filrri’using a tie/adhesive coat layer and further the two Liquid crystals are bonded through yet another tie coat layer.
  • Both tie coats are purpose engineered to adhere apolar LC films to themselves as well as to adhere to polar films, like PET film, after drying and/or curing.
  • the present application discloses ahighly secure and complex Colour shift film wherein, the obverse face of the Liquid crystal layer is further coated with a heat seal top coat layer during the process of manufacture of security thread, so as to enable the thread to adhere to paper fibers.
  • the present application discloses ahighly secure and complex Colour shift film wherein, the obverse face of the substrate is optionally coated with a fluorescent coat prior to coating of heat seal top coat layer, during the process of manufacture of security thread.
  • a tie coat based LC film is laminated onto/bonded to the“receptor” substrate, display the desired colour shift spectral values as also display higher/controlled gloss versus reflected light.
  • a tie-coat is a layer of coating that acts as a bridge between a PET and the liquid crystal coating layer. The tie-coat provides a transitional layer that bonds or improves the adhesion of the two separate coatings.
  • the high security colour shift film of the present invention is also protected by a robust overcoat like by not limited to a clear, high UV curable lacquer which helps to protect the robustness of the colour shift qualities.
  • This process includes a lacquer coating, having high gloss, scratch resistant, sebum resistant, dirt resistant and UV protective property.
  • This coating may be engineered as per the specification of the end user, and is by no way to be a limitation this process is ideally done during the process of manufacture of security thread if the robustness is not fortified by a tie coated PET film.
  • the tie coated complex LC film, as described in this invention can also be further fortified by using a lacquer coating on face side, i.e. on PET face side, in this case.
  • the colour shift film of the present application which displays consistent spectral values throughout the circulation life of the bank note, and laminating this robust colour shift security film with wide spectrum complex spectral values onto the main“receiver” substrate, to display the desired colour shift spectral values, can subsequently be used to produce high security threads for insertion in bank note paper.
  • the high security colour shift film of the present invention is prepared in such a manner so as to exhibit a wide spectrum colour shifting film, like but not limited to a spectrum of 450/700 nm or 490/700 nm, which is technically complex, wider spectrum, compared to currently available colour shift film with narrow spectrum like Blue to Green 470/540 nm.
  • a wide spectrum colour shifting film like but not limited to a spectrum of 450/700 nm or 490/700 nm, which is technically complex, wider spectrum, compared to currently available colour shift film with narrow spectrum like Blue to Green 470/540 nm.
  • the high security colour shift film of the present invention exhibits varied colour combinations from the VIBGYOR spectrum thereby making it possible to design more secure colour- shift combinations. It is difficult to exhibit/simulate such wide spectrum using vacuum metallizing or sputtering technology, as there are inherent limitations in layers one can apply with different metals or the inorganic materials, to get different types of colour shades.
  • the high security colour shift film of the present invention helps in doing commercially feasible research to find more secure combinations.
  • smaller, consistent and computer-controlled production is commercially possible.
  • Example, with the present invention a short run as small as 10 meters can be done successfully and repeatedly, when compared to at least 5000 meters of a non- consistent run in a vacuum chamber. This process allows different combinations of colour shift and makes it more commercially feasible.
  • the substrate is selected fromlike but not limited to, PET film .
  • the heat seal top coat layer comprises of anti-sebum and anti-dirt coating and consists of material such as like but not limited to, UV curable lacquer coatings.
  • the Liquid crystalLiquid crystals can be chiral, nematic/cholesteric dopants or combination thereof and forms a specific wavelength and colour shift properties.
  • the ratios of such crystals, solid contents and dilution in particular solvents will result in specific wavelengths of colour shift values.
  • the adhesive layer is selected/made of like but not limited to, acrylics, nylons, UV curable Acrylates, polyurethanes etc. as defined in the patent disclosure and is purpose engineered towards the desired property
  • the tie coat layer is selected/made of like but not limited to, UV curable Acrylates, polyurethanes etc..as defined in the patent disclosure and is purpose engineered towards the desired property
  • the present invention discloses various method of manufacturing an improved high security colour shift film, said method of manufacturing colour shift film may be brought out either individually or in combination, so as to manufacture the high security thread as disclosed in the present invention.
  • the method of manufacturing Highly secure and complex Colour shift film comprises the steps of:
  • step (a) and (b) Bringing together the stack of LC films and PET films obtained in step (a) and (b) on the side of the Liquid crystal film, and curing the same using an flash cured tie coat layer without any application of hot air; d. Delaminating/peeling off the substrate from one side of the film to obtain a high security film for further process of manufacture of security thread.
  • Fig.1 -Fig 4a and 4b illustrates a complex wide spectrum liquid crystal film, which once formed may be incorporated to provide a robust improved high security colour shift film as disclosed in the present invention.
  • Fig. 1 illustrates a liquid crystal film on a PET(l) carrier, Said PET(l) is coated with a LC polymers to form a Liquid crystal film(2) of consistent colour shift properties in a pre-defined discreet range.
  • the Liquid crystals polymeric formulation isa mixture of chiral, nematic/cholesteric, certain dopants, surfactants in precise ratios known to display a specific wavelength that is different from the liquid crystal polymeric formulation used in LC Film (3) as shown in figure Fig. 2.
  • Fig. 2 illustrates a liquid crystal film, wherein the PET (1) is used as a carrier substrate.
  • Said PET(l) is coated with a tie coat, which forms a clear dimensionally stable film, after drying and curing, which is engineered to enable better coat and adhere to apolar polymers like LC polymers and after drying and curing, to form a Liquid crystal film(3) of consistent colour shift properties in a pre-defined discreet range.
  • the Liquid crystals polymeric formulation isa mixture of chiral, nematic/cholesteric, certain dopants, surfactants in precise ratios known to display a specific wavelength that is different from the liquid crystal polymeric formulation used in LC Film (2) as shown in figure Fig. 1.
  • Fig. 3 illustrates a High security liquid crystal film, wherein both the Liquid Crystals film as disclosed in Fig. 2 and Fig. 3, are brought together, using a compatible adhesive as mentioned in the patent, to make High Security Liquid Crystal film, such that the film has wider range of colour shift.
  • Fig.4a illustrates a High security liquid crystal film, that has wider range of colour shift spectrum values and wherein the PET substrate (1) from one or both sides of the high security film shown in figure (3) can delaminated/peeled/removed off.
  • Fig.4b illustrates a High security liquid crystal film, that has wider range of colour shift and wherein the high security liquid crystal film is adheredto the PET substrate (1) via tie coat (9).
  • the present invention discloses several methods of manufacturing an improved high security colour shift film, which are described as follows
  • Step 1 Coating of the one Liquid Crystal(2) on substrate PET -> Drying of Solvents -> UV curing -> Roll 1
  • Step 2 Coating of second Liquid Crystal(3) on substrate PET - ⁇ Drying of Solvents ->UV curing -> Roll 2
  • Step 3 Combine the Roll 1 and Roll 2 on Liquid crystal side with the use of suitable Flash cured tie coat(5) to obtain security film with wide spectrum -> Roll 3
  • Step 4 On detaching one or both layers of PET substrate(l) from Roll 3, roll 4 is now ready for further use in robust High security thread
  • Figure 5 which depicts essentially a construction of high security thread, with wider spectrum of colour shifting characteristics, also discloses two inventive steps:
  • Figure 5(a) describes various layers of functional coatings as seen in a Security thread.
  • Receiver substrate (1) as defined as receptor and known to security thread manufacturers may be metallized /De-metallized having indicia(referred as (4) in the fig, may be in form of text, numbers, graphics etc..
  • the said receptor substrate is adhered /laminated with High security Liquid crystal film (as described in fig. 4a), to the said receptor substrate using aTie II (as defined ) coat, which is referred as (5) in said figure on the face side to form a high security web/roll , which is further coated with cast and cure lacquer (6), and subsequently coated with heat seal top coat (7).
  • Receiver substrate (1) is optionally coated with fluorescent coat (8) on the obverse side of the substrate followed by heat seal top coat (7) on top of the fluorescent layer (8).
  • step e UV curing/drying and optionally chilling of web as obtained from step e; g. Coating heat seal lacquer on Face side (7);
  • Receiver substrate (1) is optionally coated with fluorescent coat (8) on the obverse side of the substrate (1);
  • Figure 5(b) describes various layers of functional coatings as seen in a Security thread.
  • Receiver substrate (1) as defined as receptor and known to security thread manufacturers may be metallized /De-metallized having indicia(referred as (4) in the fig, may be in form of text, numbers, graphics etc..
  • the said receptor substrate is adhered /laminated with High security Liquid crystal film (donor film as mentioned in fig 4b, such donor film is a tie coated PET film as a substrate (1) in fig. 5b), to the said receptor substrate using aTie II (as defined ) coat, which is referred as (5) in said figure on the face side to form a high security web/roll, (That may be optionally coated with cast and cure lacquer (6)) and subsequently coated with heat seal top coat (7).
  • Receiver substrate (1) is optionally coated with fluorescent coat (8) on the obverse side of the substrate followed by heat seal top coat (7) on top of the fluorescent layer (8).
  • n Lamination of Robust high security liquid crystal film ( donor film as mentioned in fig 4b, such donor film is a tie coated PET film as a substrate (1) in fig. 5b) to the face side of the“receptor” high thread substrate (1) as shown in fig 5b;
  • Receiver substrate (1) is optionally coated with fluorescent coat (8) on the obverse side of the substrate (1);
  • the present invention discloses various method of manufacturing an improved high security colour shift film, said method of manufacturing colour shift film may be brought out either individually or in combination, so as to manufacture the high security thread as disclosed in the present invention.
  • the present invention provides an improved high security colour shift film with added complex security features, having a robust top coat that is having wide spectrum of colourshift effects than the present methods.
  • the said robust complex security film can be used to produce complex high security thread, having a robust structures as disclosed, and will be more economical compared to transfer method of LC film or Vacuum deposited particle based colour shifting film or security thread made therefrom.
  • the end product produced as per our invention shows higher or controlled gloss versus reflected light as well asprovides protection against sebum and dirt.
  • the improved high security colour shift film has longer shelf life in long term external use and may also withstand several mechanical stress and strain, which is otherwise inherent weak link while using liquid crystal or inorganic ultra thin depositions, within the structure of a security thread.
  • security thread can be used to make security thread, as shown in above processes.
  • the structure of the security thread can be enhanced further byoptionally printing/coating other security elements, like but not limited to magnetic elements, machine readable, light source readable, UV fluorescent pigments, magnetic print block, DNA taggent etc.
  • the security thread is usually displayed like“windows” during the insertion process in mould made bank note paper. It is also known as Currency paper, and after security printing, it is known as currency notes, and is used in countries worldwide.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
  • Laminated Bodies (AREA)

Abstract

L'invention concerne un film de sécurité à décalage de couleur robuste avec des valeurs spectrales plus complexes et cohérentes, pour fabriquer un fil de sécurité élevé pour une insertion ultérieure dans des substrats de haute sécurité, comme le papier pour billets de banque.
EP20727732.8A 2019-04-20 2020-04-20 Film de sécurité robuste à décalage de couleur à valeurs spectrales complexes à large spectre et fil de sécurité fabriqué à partir de celui-ci Pending EP3959081A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN201821039667 2019-04-20
PCT/IN2020/050372 WO2020217254A1 (fr) 2019-04-20 2020-04-20 Film de sécurité robuste à décalage de couleur à valeurs spectrales complexes à large spectre et fil de sécurité fabriqué à partir de celui-ci

Publications (1)

Publication Number Publication Date
EP3959081A1 true EP3959081A1 (fr) 2022-03-02

Family

ID=70802906

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20727732.8A Pending EP3959081A1 (fr) 2019-04-20 2020-04-20 Film de sécurité robuste à décalage de couleur à valeurs spectrales complexes à large spectre et fil de sécurité fabriqué à partir de celui-ci

Country Status (2)

Country Link
EP (1) EP3959081A1 (fr)
WO (1) WO2020217254A1 (fr)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3942663A1 (de) * 1989-12-22 1991-06-27 Gao Ges Automation Org Datentraeger mit einem fluessigkristall-sicherheitselement
DE19907697A1 (de) 1999-02-23 2000-08-24 Giesecke & Devrient Gmbh Wertdokument
GB0201767D0 (en) 2002-01-25 2002-03-13 Rue De Int Ltd Improvements in methods of manufacturing substrates
DE10349000A1 (de) 2003-10-17 2005-05-19 Giesecke & Devrient Gmbh Sicherheitselement mit Farbkippeffekt
DE102004021246A1 (de) * 2004-04-30 2005-11-24 Giesecke & Devrient Gmbh Sicherheitselement und Verfahren zu seiner Herstellung
DE102007034716A1 (de) 2007-07-23 2009-01-29 Giesecke & Devrient Gmbh Sicherheitselement
GB2474903B (en) * 2009-10-30 2012-02-01 Rue De Int Ltd Improvements in security devices

Also Published As

Publication number Publication date
WO2020217254A8 (fr) 2021-06-03
WO2020217254A9 (fr) 2021-12-09
WO2020217254A1 (fr) 2020-10-29

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