WO1994013749A1 - Thin film security device (tfsd) application process and adhesive therefor - Google Patents

Thin film security device (tfsd) application process and adhesive therefor Download PDF

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Publication number
WO1994013749A1
WO1994013749A1 PCT/CA1993/000519 CA9300519W WO9413749A1 WO 1994013749 A1 WO1994013749 A1 WO 1994013749A1 CA 9300519 W CA9300519 W CA 9300519W WO 9413749 A1 WO9413749 A1 WO 9413749A1
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WO
WIPO (PCT)
Prior art keywords
curable
ultraviolet radiation
oligomers
sensitive adhesive
substrate
Prior art date
Application number
PCT/CA1993/000519
Other languages
French (fr)
Inventor
Alice Hibbert Pincus
Original Assignee
Bank Of Canada
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 Bank Of Canada filed Critical Bank Of Canada
Priority to AU55580/94A priority Critical patent/AU5558094A/en
Publication of WO1994013749A1 publication Critical patent/WO1994013749A1/en

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/0012—Processes making use of the tackiness of the photolithographic materials, e.g. for mounting; Packaging for photolithographic material; Packages obtained by processing photolithographic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
    • B41M3/14—Security printing
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F290/00—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups
    • C08F290/02—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups on to polymers modified by introduction of unsaturated end groups
    • C08F290/06—Polymers provided for in subclass C08G
    • C08F290/061—Polyesters; Polycarbonates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J167/00—Adhesives based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Adhesives based on derivatives of such polymers
    • C09J167/06—Unsaturated polyesters having carbon-to-carbon unsaturation
    • C09J167/07—Unsaturated polyesters having carbon-to-carbon unsaturation having terminal carbon-to-carbon unsaturated bonds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
    • C09J4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/40—Agents facilitating proof of genuineness or preventing fraudulent alteration, e.g. for security paper

Definitions

  • the present invention relates to a combination of components to obtain a temporarily pressure-sensitive UV curable adhesive, and more particularly to a combination of components to obtain a printable pigmented temporarily pressure sensitive UV curable adhesive. Still more particularly, the present invention relates to formulations which can be printed as an ink, then become temporarily pressure sensitive adhesives upon exposure to ultraviolet light, attaining a high tack state for transferring dielectric material thereto, and within hours permanently bonds to the dielectric material to form a thin film security device (TFSD) .
  • TFSD thin film security device
  • the application of dielectric material to valuable documents has been found to provide excellent security devices.
  • the dielectric material is applied in a thin layer to the document by either a conventional labelling technique or a hot foil stamping technique.
  • SUBSTITUTE SHEET - 2 - provide a thin film security device of minimum thickness.
  • the present invention also provides an ultraviolet radiation curable temporarily pressure-sensitive adhesive composition which comprises:
  • At least one polymerizable component selected from the group consisting of acrylic monomers, oligomers thereof, blends of said acrylic monomers and oligomers, and blends of said acrylic monomers or oligomers with a vinyl ether monomer;
  • a printable ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition which comprises:
  • the present invention also provides a printable pigmented ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition which comprises:
  • the printable pigmented UV radiation curable temporarily pressure-sensitive adhesive composition of this invention as described in the two immediately preceding paragraphs has the following properties: (1) it is printable on a relatively smooth paper substrate with good edge definition and uniform ink thickness;
  • the above-described adhesive composition is printable by an offset gravure process and has a viscosity near 20 poise at 25 degrees
  • the dry film has an optical density greater than 1.4.
  • a method of providing a substrate with indicia which comprises:
  • the present invention further provides an article - 6 - of manufacture comprising: a substrate, to selected areas on the surface of said substrate is permanently bonded a semi- transparent dielectric material, said bonding being by means of the printable ultraviolet radiation-curable temporarily pressure-sensitive adhesive having the constitution and characteristics as set forth hereinabove.
  • the present invention still further provides an article of manufacture which comprises a pattern of patches of semi-transparent dielectric materials and/or a very thin layer of metal, permanently bonded to banknote paper by means of a black UV radiation- curable temporarily pressure sensitive adhesive having the constitution and characteristics as set forth hereinabove.
  • the ultraviolet radiation-curable temporarily pressure-sensitive adhesive which comprises one aspect of the present invention comprises the following components:
  • polyesters (a) One or more saturated copolyesters with some terminal acrylic double bonds and hydroxyl functionality. More specifically, the preferred polyester or blend of polyesters is that known under the tradename of "Dynacoll A", the exact composition of which is not known to the applicant; they are in the form of viscous liquids. Specific polyesters which have been found particularly useful in the present invention are those designated by the tradenames "Dynacoll A 3130", “Dynacoll A 3170” and "Dynacoll A 3251".
  • the “Dynacoll A” polyesters are saturated copolyesters, which are partially terminally acrylated; having the following general structure: Ax v - saturated polyester - B v y wherein A represents a group containing a double bond - 7 - reactive to energy-rich radiation; B represents a group non-reactive to radiation; and x + y_ is equal to the functionality of the polyester.
  • These polyesters are further characterized by having an average molecular weight from 3,000 to 6,000; and they have a large number of preferably branched alkyl side chains in the molecule, and have glass transition temperatures ranging from -10°C to -50°C.
  • a carbon black pigment which is dispersed in an acrylate monomer More specifically the carbon black pigment dispersion which has been found particularly effective is one known under the tradename "Pennco 9B1" which is a dispersion of carbon black pigments in trimethylolpropane triacrylate (TMPTA) at approximately 20% by weight pigment concentration.
  • Pennco 9B1 is a dispersion of carbon black pigments in trimethylolpropane triacrylate (TMPTA) at approximately 20% by weight pigment concentration.
  • One or more vinyl ether monomers such as for example 4-hydroxybutylvinylether (HBVE) , cyclohexylvinylether (CHVE) , and triethyleneglycol divinylether (DVE-3) , or oligomers thereof, or blends of the aforesaid vinyl ether monomers and oligomers.
  • HBVE 4-hydroxybutylvinylether
  • CHVE cyclohexylvinylether
  • DVE-3 triethyleneglycol divinylether
  • Free radical photoinitiators which have been found to be effective are acetophenone derivatives such as 2-hydroxy-2-methyl-l-phenylpropan- 1-one known by the tradename of "Darocur 1173", or - 8 - diethoxy acetophenone, or a blend of the first- mentioned acetophenone derivatives with a thioxanthone and an amine benzoate, known under the tradename of "Darocur 4043"; or an acetophenone derivative having also amine functionality, specifically the compound 2 -benzyl-2 - ( dimethylamino ) - 1- [ 4 - ( 4 - morpholinyl)phenyl]-l-butanone, known under the tradename of "Irgacure 369".
  • acetophenone derivatives such as 2-hydroxy-2-methyl-l-phenylpropan- 1-one known by the tradename of "Darocur 1173", or - 8 - diethoxy acetophenone, or
  • Cationic photoinitiators which have been found to be effective are triaryl sulfonium salts of hexafluorophosphate, known by the tradenames "FX 512" and “Cyracure UVI 6990", and of hexafluoroantimonate, known by the tradename "Cyracure UVI 6974".
  • a cationic photoinitiator is not essential if an amine functionality is present in the free radical photoinitiator combination.
  • the amounts of reactive oligomers - component (a) and component (b) (unpigmented) - ranges from 60% to 80% by weight, and the amount of vinyl ether monomer (component (c) ) may range from 15% to 26% by weight, based on the total composition.
  • the acrylated copolyester To prepare the adhesive, the acrylated copolyester must be heated to allow dispensing into a tared container. Either the pigment dispersion or the vinyl ether or both are then added and blended, heating to 50°C as necessary to facilitate mixing. The rest of the ingredients can be added and mixed in at room temperature. The mixing may be effected by any suitable means known in the art.
  • the pressure-sensitive adhesive as described above is storage stable (ie. has a shelf life of at least 2 years.)
  • the pressure-sensitive adhesive is obtained by UV curing of saturated copolyesters with some terminal acrylic double bonds and hydroxyl functionality, viz., component (a) of the foregoing composition; and it is the addition of vinyl ether monomers that cause further reaction with the adhesive to cause it to form a dry and permanent film.
  • the "Dynacoll A" polyesters are designed to be applied to a substrate by hot melt apparatus, and upon cure to form permanently tacky films.
  • the addition of the vinyl ether monomer (component (c) to the saturated copolyester serves to dilute the copolyester adhesive so as to provide an adhesive viscosity low enough for printing application to banknote paper as described hereinafter while at the same time ensuring that sufficiently high tack is developed for the transfer step.
  • the vinyl - 10 - ether reacts with residual reactive groups of the copolyester to form a dry and durable film.
  • the adhesive composition for application to a substrate such as bank note paper must be printable. This places limits on the viscosity of the composition. If the formulation is too fluid, it will be absorbed by the paper substrate. If the formulation is too viscous, it will not print cleanly, resulting in poor line resolution and scumming in non- image areas.
  • the "Dynacoll" oligomers must be diluted with monomer(s) to reduce their viscosity to make them printable. Monomers differ in their efficiency as diluents. The ratio of oligomer(s)to monomer(s) is targeted to obtaining the optimum application viscosity.
  • the composition must cure upon exposure to UV radiation (2 x 300 watts per inch) at 200 feet per minute.
  • Cure speed is a function of formulation components, application thickness and UV intensity. Typically, the thinner the layer, the faster the cure speed and the higher the UV intensity the greater the potential cure speed. In terms of formulation components, cure speed is dependent on the photoinitiator type and level, the colour, and the chemical structure of the oligomers and monomers.
  • the formulation is black and the level of black pigment is determined by the desired optical density of the cured adhesive. If less black pigment is used, the optical density would be too low. The more black pigment which is used, the slower the cure speed.
  • the "Dynacoll" oligomers are not high speed curing materials.
  • substrate to which the adhesive of the present invention can be applied it has been specifically designed to be applied to the smoother side of banknote paper. We have found that much poorer application and transfer are obtained on the rougher side of the banknote. We have also found that excellent results are obtained when this adhesive is applied to very smooth and/or non absorbent surfaces such as supercalendered papers and plastic films.
  • the UV radiation-curable temporarily- pressure-sensitive adhesive compositions include a pigment (and more particularly a black pigment) to render the composition printable
  • the compositions of the invention in its broadest aspects need not necessarily include a pigment.
  • Such adhesive compositions without the presence of a pigment would be "clear", and would not be printable, but otherwise have all the desirable characteristics of the UV radiation curable temporarily pressure- sensitive adhesives of the invention as previously described, viz. the adhesives are temporarily pressure-sensitive, and upon exposure to ultraviolet radiation become highly tacky within about 1 second and are curable to a tack-free state within 24 hours to yield a durable scratch-resistant surface.
  • I intensity of incident light and I is the intensity of the reflected light.
  • the viscosity of the adhesive in its non- activated state ranges from about 3500-5200 cps. at 20°C.
  • the thin film security device to which reference has been made earlier in this specification is a reflective surface which switches colour when a viewer observes it from different angles.
  • Bank notes with the TFSD are easily identified as genuine but difficult to counterfeit.
  • the TFSD optical coating material is supplied as a very thin releasable layer deposited on a plastic carrier ribbon.
  • the above-described adhesive is used to secure the coating to banknotes in the following manner: /A motif (patch) in adhesive ink, approximately 10 mm by 12 mm, is printed over the - 15 - lithographic background on the face of each banknote. Each note is then exposed to ultra-violet light to begin curing of the adhesive.
  • the plastic carrier ribbon is then forced into contact with the printed adhesive motif as it cures.
  • This application under appropriate pressure, ensures the instant formation of a positive bond between all three elements: the optical coating, the adhesive, and the banknote. Separation of the plastic ribbon from the banknote releases a portion of the TFSD optical coating onto the banknote surface in the exact image of the printed motif.
  • Figure 1 is a schematic drawing of the laminate and substrate before application.
  • Figure 2 is a schematic drawing of the laminate and substrate after application.
  • Figure 3 is a plan view of a sheet of banknote paper to which an array of patches of UV radiation curable printable pressure-sensitive adhesive according to the present invention has been applied.
  • the UV radiation curable pressure-sensitive adhesive (4) is applied to a substrate or a document (5) by an offset gravure printing process or other similar printing application.
  • the adhesive (4) is applied in patches on the document (5) in the shape of the final transferred thin film security device.
  • the substrate or document (5) is preferably banknote paper, but may be other suitable paper carriers which, if desired, could be calendered or plastic coated.
  • the maximum thickness of the adhesive (4) applied is - 16 -
  • Figure 3 illustrates a typical array of patches of the adhesive applied to a sheet of banknote paper. After the adhesive (4) is applied to the substrate (5) it is subjected to ultraviolet radiation. When the adhesive is exposed to ultraviolet light the photoinitiators therein initiate the polymerization of the adhesive.
  • the polymerization of the adhesive advances it to a tacky state.
  • the adhesive is able to attain a highly tacky state by the action of ultraviolet radiation in less than 1 second after treatment.
  • the thin film of transparent dielectric material is brought into contact with the adhesive.
  • the dielectric material is one of three layers of a laminate.
  • the three layers of the laminate are: a polyester film of a thickness of 12-25 / xm
  • the polyester film is comprised of polyethylene terephthalate, a readily available material sold under such trade designations as "Mylar” R , "Hostaphan”TM and “Melinex”TM.
  • the release coating may be of any suitable release material known in the art. A suitable thickness of the release coating is about 5 micrometres.
  • the dielectric material layers (3) are made up of five layers, the outermost layers of which are of zirconia (Zr0 2 ) , a central layer also of zirconia, and sandwiched between the outer and innermost zirconia layers are two layers of silica, the total thickness of the combined layers of dielectric material being about 0.8 microns.
  • the dielectric material may be comprised of outer layers of metal. - 17 - between which is a layer of silica (Si0 2 ) or alumina (A1 2 0 3 ) .
  • One of the metal layers is of aluminum, and the other is "Inconel” (trademark), a nickel based, heat- and oxidation-resistant alloy with approximately 13% chromium, 6% iron, and small amounts of manganese, silicon and/or copper.
  • the thin film security material (TFSM) which is used with a clear adhesive is that known as metal-dielectric, i.e. that described in the last two sentences of the immediately preceding paragraph.
  • the aluminum layer in the metal-dielectric TFSM is effectively fully reflective so there is no optical requirement for a pigmented (preferably black) adhesive in this case, as there is for the semi- transparent all-dielectric TFSM (thin film security material) .
  • the layered thin film stack as described above is deposited on a polyethylene terephthalate web (380 mm wide, 0.025 mm thick and 1700 metres long), in a vacuum roll coater manufactured by Ulvac Japan.
  • Zirconia and silica are heated by electron beams of approximately 20 KW power.
  • the deposition thickness is controlled by varying the speed at which material is moved under the electron beam, the beam current, and the sweep patterns of the electron beams.
  • Zirconia and silica are deposited in a single pass of the web through the two deposition chambers in the roll coater.
  • a final bond strength is obtained in less than 200 hours after pressurized transfer at 40 psi for 250 milliseconds.
  • the pressurized transfer can be done with transfer pads on a Thin Film Application and Conversion System (TACS) .
  • TACS Thin Film Application and Conversion System
  • the Thin Film Application and Conversion System is a horizontal process machine where stacked bank note sheets are fed in one end and move on a flat horizontal path through each" of the process sections to exit in stacked format at the opposite end.
  • the sheet feeder is a 5000 sheet capacity unit manufactured by Autofeeds London Ltd. , London, England. The sheets are stacked with the longitudinal axis of the individual bank notes parallel to the process axis of the machine.
  • Sheets are stream fed in shingled fashion with the trailing edge of each sheet - 19 - overlapping the leading edge of the following sheet. Sheets are guided against a side lay on the feed board by skewed tapes and fed to a registration stop for transfer to the sheet transport system.
  • the sheet transport system consists of an endless dual chain and sprocket system equipped with mechanical grippers running in a horizontal track mounted below the top surface of a transport table.
  • the bank note sheets are held by the same grippers throughout the application process and move in a "web like" stream with a 6 inch (152 mm) longitudinal pitch spacing between individual bank notes, maintained from sheet to sheet by overlapping leading and trailing edges in shingled fashion. The double thickness caused by this overlapping is accommodated by the resilience of the printing and application rollers.
  • the printing system uses a gravure offset process to deposit a measured portion of the above-described printable adhesive as a small printed motif on the surface of each bank note.
  • the etched gravure cylinder is charged with ink using a double doctor blade and ink well system manufactured by Inta Roto Co.
  • the gravure cylinder transfers the adhesive ink to a relieved rubber offset cylinder.
  • the offset cylinder deposits the ink directly onto the note sheet as the sheet passes horizontally beneath it through the nip created with the matching impression cylinder mounted beneath the transport table.
  • the offset and impression rollers are relieved to permit passage of the transport system grippers.
  • the UV curing stage is manufactured by Fusion UV Curing System, Rockville, Maryland, USA.
  • the bank note sheets are passed beneath the curing unit and exit to the TFSM application stage.
  • the adhesive begins curing on exposure to ultra- - 20 - violet (UV) light.
  • the curing time is a function of the duration of the exposure and the intensity of the light source.
  • TFSM thin film security material
  • the ultraviolet radiation is provided by ultraviolet lamps having an output power rating of a minimum of 600 watts per inch transverse to the path of travel of the bank note sheets through the TACS. Suitable lamps for this purpose are two banks of Fusion Systems Corp. "D" lamps or equivalent.
  • the application stage consists of a plurality of disc shaped rotary application units stacked side by side across the width of the transport table.
  • the outside circumference of each rotary application unit is contoured with raised pressure points similar to gear teeth.
  • the pitch of the pressure points matches the longitudinal pitch spacing of the individual notes on each sheet (6 in.).
  • the application units are matched to an impression cylinder beneath the transport table which creates a nip to provide the required application pressure.
  • the ribbons of TFSM are contained in a plurality of cassette type storage and handling units which are individually mounted within each application unit.
  • each application unit rotates in synchronization with the velocity of the bank note sheets moving on the transport table, the ribbons wind in and out of each cassette while being drawn on a circular path covering the pressure points around the circumference of each application unit.
  • the indexing action of each application unit moves a fresh portion of TFSM ribbon over each pressure point as that particular point rotates into contact with an adhesive motif on the bank note sheets passing through the nip.
  • the TACS forces the laminate or thin film security material (TFSM) ribbon into direct contact with the adhesive motif with sufficient force to cause a complete transfer of the TFSM material to the bank note surface, separates the TFSM ribbon from the surface, and indexes the ribbon to the next section of coating for application.
  • the application device applies a contact force equivalent to the force produced by rolling line contact, the contact force being adjustable in a range of 100 to 1000 N with a mean operating force of 200 N, such as to provide optimum control of adhesive deposition and image density.
  • the transport system delivers the bank note sheets to a stacker unit which is also manufactured by Autofeeds London Ltd. The stacker piles the sheets in stacks of up to 5000 sheets.
  • the patches of permanently bonded dielectric material provide a security device for which tampering, counterfeiting and copying of the substrate is made more difficult. For example, to photocopy the article with the attached dielectric material will result in an inaccurate copy.
  • the dielectric material reflects coloured light such that the resulting copy will contain areas corresponding to the patches of dielectric material which will be distorted. Any - 22 - attempt to tamper with or remove the dielectric material will damage the article by possibly tearing the document so that successful copying is not possible.
  • the thin film security device (TFSD) produced in accordance with the present invention which device incorporates a UV cured adhesive as previously described, must meet a number of requirements so that it is durable in use, that is, so that the thin film security device (TFSD) will last at least as long as any bank note to which it is applied.
  • Tester Crumpled specimens are compared with existing exemplars from previous tests. - 23 -
  • abrasion testing device similar to the Taber Abraser, a test is performed first on an area of the specimen note not containing a TSFD, to establish the effect of abrasion on intaglio ink. Two abrasion intensities are established; the first corresponding to just noticeable wear of the intaglio ink, the second corresponding to obvious wear. Two TFSD specimens are then subjected to the same treatments using the Taber model 503 Abraser, testing is performed with Taber CS10 abrading wheels with a standard 250 gram loading. The test is run for 100 cycles, after which just noticeable wear of the intaglio print of the bank note has occurred. Abraded specimens are compared to existing exemplars from previous tests, (iii) Laundering Test - to evaluate the ability of the
  • TSFD printed note to withstand laundering Using a TFSD specimen secured to an article. of clothing, the specimen is subjected to a normal hot wash laundering cycle using a powerful detergent. Samples are enclosed in shirt pockets and subjected to a normal hot wash cycle: 3/4 cup (approximately 170 ml)
  • Samples (e) , (f) and (g) were water rinsed to remove the chemical before drying.
  • Acetone at 23°C for 2 hours.
  • Ethyl alcohol 95% at 65°C for 2 hours.
  • Sulphuric acid 5% solution, aqueous, at 65°C for 2 hours.
  • Adhesive formulations were prepared by mixing together the following ingredients, in the proportions indicated, as expressed in Table 1:
  • Tests were run on the TACS using the formulations given in Table 1. Viscosities were measured just prior to testing and adjusted with the appropriate vinyl ether diluent where necessary. Each test run was first made with one bank of UV lamps and the machine speed was increased from 120 to 140 to 160 feet per minute; and then a second bank of UV lamps was turned on and the machine speed was decreased from 160 to 140 to 120 feet per minute. Results are shown in Table 2.
  • IB single bank of UV lamps

Abstract

An ultraviolet (UV) radiation-curable temporarily pressure sensitive composition which when irradiated with ultraviolet light quickly attains a high tack state for transferring dielectric material thereto, and within hours permanently bonds to the dielectric material to form a thin film security device (TFSD). The UV radiation-curable pressure sensitive adhesive comprises, in one aspect: (a) at least one saturated copolyester having terminal acrylic double bonds and hydroxyl moieties; (b) at least one pigment dispersed in a liquid selected from the group consisting of an acrylic monomer, a vinyl ether monomer, oligomers thereof, and blends thereof; (c) at least one vinyl ether monomer, oligomers thereof, or blends of said vinyl ether monomer and oligomers; and (d) at least one photoinitiator in a quantity sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation. In another aspect the UV radiation-curable temporarily-pressure-sensitive adhesive is as described above with the exception that it is 'clear', i.e. contains no pigment. The invention also provides a method of providing a substrate (and more specifically, banknote paper) with indicia, which comprises: (1) forming a laminate of (a) a polyester film having a thickness of 12-25 microns, (b) a release coating of a thickness of 1-2 microns, (c) a protective layer 1-2 microns thick, and (d) a stack of dielectric and/or metal layers having a maximum thickness of 1 micron; (2) providing a plurality of areas on the substrate, each of which areas bear a UV-curable pressure-sensitive adhesive as described above; (3) sujecting the substrate containing the aforesaid adhesive-bearing areas to UV radiation to cause the areas to become highly tacky; (4) bringing the outer surface of the stack of dielectric and/or metal layers into pressurized contact with the adhesive-bearing areas on the substrate, thereby adhering the laminate to the adhesive-bearing areas on the substrate; and (5) stripping the laminate away from the substrate, whereby the dielectric and/or metal layers are sheared from the release coating and firmly adhere to said adhesive-bearing areas on the substrate.

Description

THIN FILM SECURITY DEVICE (TFSD) APPLICATION PROCESS
AND ADHESIVE THEREFOR
FIELD OF INVENTION
The present invention relates to a combination of components to obtain a temporarily pressure-sensitive UV curable adhesive, and more particularly to a combination of components to obtain a printable pigmented temporarily pressure sensitive UV curable adhesive. Still more particularly, the present invention relates to formulations which can be printed as an ink, then become temporarily pressure sensitive adhesives upon exposure to ultraviolet light, attaining a high tack state for transferring dielectric material thereto, and within hours permanently bonds to the dielectric material to form a thin film security device (TFSD) .
The application of dielectric material to valuable documents has been found to provide excellent security devices. The dielectric material is applied in a thin layer to the document by either a conventional labelling technique or a hot foil stamping technique.
Conventional labelling techniques involve a process wherein pressurized contact is used to bond the dielectric material to a suitable document or substrate. However, the proposed conventional labelling techniques have required elaborate transfer processes which in many cases do not provide a permanent bond between substrate and dielectric material. Furthermore, the dielectric film once bonded is relatively thick which can cause distortion of the document and handling problems.
SUBSTITUTE SHEET - la-
The present invention provides a unique pressure sensitive adhesive which permanently bonds a dielectric material in an uncomplicated room temperature conventional labelling technique to
SUBSTITUTE SHEET - 2 - provide a thin film security device of minimum thickness.
SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided an ultraviolet radiation curable temporarily pressure-sensitive adhesive composition comprising:
(a) at least one saturated copolyester having terminal acrylic double bonds and hydroxyl moieties; (b) at least one polymerizable component selected from the group consisting of acrylic monomers, oligomers thereof, blends of said acrylic monomers and oligomers, and blends of said acrylic monomers or oligomers with a vinyl ether monomer; (c) at least one vinyl ether monomer, or oligomers thereof, or blends of said vinyl ether monomer and oligomers; and
(d) at least one photoinitiator in a quantity sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation, said adhesive composition being curable to a tack-free state within 24 hours.
The present invention also provides an ultraviolet radiation curable temporarily pressure- sensitive adhesive composition which comprises:
(a) at least one saturated copolyester with some terminal acrylic double bonds;
(b) at least one polymerizable component selected from the group consisting of acrylic monomers, oligomers thereof, blends of said acrylic monomers and oligomers, and blends of said acrylic monomers or oligomers with a vinyl ether monomer;
(c) at least one vinyl ether monomer, or oligomers thereof, or blends of said vinyl ether monomer and oligomers; - 3 -
(d) at least one free radical photoinitiator and/or photosensitizer; and
(e) at least one cationic photoinitiator; the photoinitiator(s) being present in an amount sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation, said adhesive composition being curable to a tack-free state within 24 hours.
According to the present invention in a further aspect there is provided a printable ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition which comprises:
(a) at least one saturated copolyester having terminal acrylic double bonds and hydroxyl moieties;
(b) at least one pigment dispersed in a liquid selected from the group consisting of an acrylic monomer, a vinyl ether monomer, oligomers thereof, and blends thereof; (c) at least one vinyl ether monomer, or oligomers thereof, or blends of said vinyl ether monomers and oligomers; and (d) at least one photoinitiator in a quantity sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation, said adhesive composition being curable to a tack-free state within 24 hours.
The present invention also provides a printable pigmented ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition which comprises:
(a) at least one saturated copolyester with some terminal acrylic double bonds; (b) at least one pigment dispersed in a liquid - 4 - selected from the group consisting of an acrylic monomer, a vinyl ether monomer, oligomers thereof, and blends thereof;
(c) at least one vinyl ether monomer, or oligomers thereof, or blends of said vinyl ether monomer and oligomers;
(d) at least one free radical photoinitiator and/or photosensitizer; and
(e) at least one cationic photoinitiator; the photoinitiator(s) being present in an amount sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation, said adhesive composition being curable to a tack-free state within 24 hours.
The printable pigmented UV radiation curable temporarily pressure-sensitive adhesive composition of this invention as described in the two immediately preceding paragraphs has the following properties: (1) it is printable on a relatively smooth paper substrate with good edge definition and uniform ink thickness;
(2) it is effective as a high tack adhesive at a maximum coating thickness of 12 microns; (3) it is activatable to a tacky state upon exposure to either a medium pressure mercury vapor electrode (125 to 700 W/inch) or microwave powered electrodeless (300 W/inch or 600 W/inch) UV lamps at speeds up to 900 ft./min. depending on the light intensity;
(4) it is curable to a tack-free state within 24 hours; and
(5) when cured, it is resistant to solvents and washing machine laundering, and is also resistant to abrasion, folding and crumpling. - 5 -
Preferably the above-described adhesive composition is printable by an offset gravure process and has a viscosity near 20 poise at 25 degrees
Centigrade. The dry film has an optical density greater than 1.4.
According to another aspect of the present invention there is provided a method of providing a substrate with indicia, which comprises:
(1) forming a laminate of (a) a polyester film of a thickness of 12-
25 microns;
(b) a release coating of a thickness of 1-2 microns;
(c) a protective layer 1-2 microns thick; and
(d) a stack of dielectric and/or metal layers having a maximum thickness of 1 micron;
(2) providing said substrate with a plurality of areas, each bearing a printable pigmented ultraviolet radiation curable temporary pressure sensitive adhesive having the constitution and characteristics as set forth above;
(3) subjecting said substrate containing said adhesive-bearing areas to ultraviolet radiation to render said areas tacky;
(4) bringing the outer surface of said stack of dielectric and/or metal layers into pressurized contact with said adhesive-bearing areas on said substrate, thereby adhering said laminate to said areas on said substrate; and (5) stripping said laminate away from the substrate, whereby the dielectric and metal layers are sheared from the release coating and firmly adhere to said areas on said substrate. The present invention further provides an article - 6 - of manufacture comprising: a substrate, to selected areas on the surface of said substrate is permanently bonded a semi- transparent dielectric material, said bonding being by means of the printable ultraviolet radiation-curable temporarily pressure-sensitive adhesive having the constitution and characteristics as set forth hereinabove.
The present invention still further provides an article of manufacture which comprises a pattern of patches of semi-transparent dielectric materials and/or a very thin layer of metal, permanently bonded to banknote paper by means of a black UV radiation- curable temporarily pressure sensitive adhesive having the constitution and characteristics as set forth hereinabove.
The ultraviolet radiation-curable temporarily pressure-sensitive adhesive which comprises one aspect of the present invention comprises the following components:
(a) One or more saturated copolyesters with some terminal acrylic double bonds and hydroxyl functionality. More specifically, the preferred polyester or blend of polyesters is that known under the tradename of "Dynacoll A", the exact composition of which is not known to the applicant; they are in the form of viscous liquids. Specific polyesters which have been found particularly useful in the present invention are those designated by the tradenames "Dynacoll A 3130", "Dynacoll A 3170" and "Dynacoll A 3251". The "Dynacoll A" polyesters are saturated copolyesters, which are partially terminally acrylated; having the following general structure: Axv - saturated polyester - Bvy wherein A represents a group containing a double bond - 7 - reactive to energy-rich radiation; B represents a group non-reactive to radiation; and x + y_ is equal to the functionality of the polyester. These polyesters are further characterized by having an average molecular weight from 3,000 to 6,000; and they have a large number of preferably branched alkyl side chains in the molecule, and have glass transition temperatures ranging from -10°C to -50°C. For a further description of these partially acrylated saturated polyester resins and how they may be employed in formulating pressure-sensitive adhesives, reference is made to the technical paper of Hans F. Huber and Hartmut Mύller, entitled "Radiation Curable Polyesters for the Formulation of Pressure-Sensitive Adhesives", Radiation Phvs. Chem.. Vol. 33, No. 5, pp. 443-450 (1989) , said publication being incorporated herein by reference.
(b) A carbon black pigment which is dispersed in an acrylate monomer. More specifically the carbon black pigment dispersion which has been found particularly effective is one known under the tradename "Pennco 9B1" which is a dispersion of carbon black pigments in trimethylolpropane triacrylate (TMPTA) at approximately 20% by weight pigment concentration.
(c) One or more vinyl ether monomers, such as for example 4-hydroxybutylvinylether (HBVE) , cyclohexylvinylether (CHVE) , and triethyleneglycol divinylether (DVE-3) , or oligomers thereof, or blends of the aforesaid vinyl ether monomers and oligomers.
(d) One or more free radical photoinitiators and/or photosensitizers. Free radical photoinitiators which have been found to be effective are acetophenone derivatives such as 2-hydroxy-2-methyl-l-phenylpropan- 1-one known by the tradename of "Darocur 1173", or - 8 - diethoxy acetophenone, or a blend of the first- mentioned acetophenone derivatives with a thioxanthone and an amine benzoate, known under the tradename of "Darocur 4043"; or an acetophenone derivative having also amine functionality, specifically the compound 2 -benzyl-2 - ( dimethylamino ) - 1- [ 4 - ( 4 - morpholinyl)phenyl]-l-butanone, known under the tradename of "Irgacure 369".
(e) One or more cationic photoinitiators. Cationic photoinitiators which have been found to be effective are triaryl sulfonium salts of hexafluorophosphate, known by the tradenames "FX 512" and "Cyracure UVI 6990", and of hexafluoroantimonate, known by the tradename "Cyracure UVI 6974". A cationic photoinitiator is not essential if an amine functionality is present in the free radical photoinitiator combination.
The above components of the printable UV radiation-curable temporarily pressure-sensitive adhesive composition of the present invention are employed in the following relative proportions, expressed in percentages by weight, based on the entire composition:
(a) Acrylated copolyester 50 - 60% (b) Carbon black pigment dispersion 11 - 15%
(pigment concentration in the range of 2.2 - 3.0% of the total composition)
(c) Vinyl ether monomer 18 -38% (preferably in the range of
25.0 - 35.0%)
(d) Free radical photoinitiators 1 - 6%
(e) Cationic photoinitiators 0 - 2% (and 0 - 6% by weight, based on component
(c))
If the UV radiation-curable temporarily-pressure- - 9 - sensitive adhesives of the present invention are "clear", i.e. containing no pigment, the amounts of reactive oligomers - component (a) and component (b) (unpigmented) - ranges from 60% to 80% by weight, and the amount of vinyl ether monomer (component (c) ) may range from 15% to 26% by weight, based on the total composition.
To prepare the adhesive, the acrylated copolyester must be heated to allow dispensing into a tared container. Either the pigment dispersion or the vinyl ether or both are then added and blended, heating to 50°C as necessary to facilitate mixing. The rest of the ingredients can be added and mixed in at room temperature. The mixing may be effected by any suitable means known in the art.
The pressure-sensitive adhesive as described above is storage stable (ie. has a shelf life of at least 2 years.)
The pressure-sensitive adhesive is obtained by UV curing of saturated copolyesters with some terminal acrylic double bonds and hydroxyl functionality, viz., component (a) of the foregoing composition; and it is the addition of vinyl ether monomers that cause further reaction with the adhesive to cause it to form a dry and permanent film. The "Dynacoll A" polyesters are designed to be applied to a substrate by hot melt apparatus, and upon cure to form permanently tacky films. The applicant has found that the addition of the vinyl ether monomer (component (c) to the saturated copolyester serves to dilute the copolyester adhesive so as to provide an adhesive viscosity low enough for printing application to banknote paper as described hereinafter while at the same time ensuring that sufficiently high tack is developed for the transfer step. In addition, after curing, the vinyl - 10 - ether reacts with residual reactive groups of the copolyester to form a dry and durable film.
There are several factors that limit the concentration of certain components. 1. The adhesive composition for application to a substrate such as bank note paper must be printable. This places limits on the viscosity of the composition. If the formulation is too fluid, it will be absorbed by the paper substrate. If the formulation is too viscous, it will not print cleanly, resulting in poor line resolution and scumming in non- image areas. The "Dynacoll" oligomers must be diluted with monomer(s) to reduce their viscosity to make them printable. Monomers differ in their efficiency as diluents. The ratio of oligomer(s)to monomer(s) is targeted to obtaining the optimum application viscosity.
2. The composition must cure upon exposure to UV radiation (2 x 300 watts per inch) at 200 feet per minute. Cure speed is a function of formulation components, application thickness and UV intensity. Typically, the thinner the layer, the faster the cure speed and the higher the UV intensity the greater the potential cure speed. In terms of formulation components, cure speed is dependent on the photoinitiator type and level, the colour, and the chemical structure of the oligomers and monomers. In a preferred application of the present invention the formulation is black and the level of black pigment is determined by the desired optical density of the cured adhesive. If less black pigment is used, the optical density would be too low. The more black pigment which is used, the slower the cure speed. The "Dynacoll" oligomers are not high speed curing materials. In order to achieve the desired cure - 11 - speed, fast photoinitiators and/or fast curing monomers must be used. However, the fastest free radical curing monomers tend to produce harder polymers, which means, less tacky surfaces. We have therefore endeavoured to optimize the level of TMPTA (trimethylolpropane triacrylate) in order to balance cure speed with tack.
We have found that certain vinyl ether monomers are excellent diluents for "Dynacoll" oligomers, appear to improve cure speed and definitely play an important role in postcuring (cationic curing) of the final product. Again the limitations on the level of vinyl ether used is determined by desired composition viscosity. 3. The composition must be a temporary pressure sensitive adhesive to allow transfer of TFSM and then permanently bond the TFSM to banknotes. We have found that this requirement is met by a dual cure UV system. The free radical cure of "Dynacoll" oligomers results in a pressure sensitive adhesive. Postcuring, presumably by cationic cure, hardens the adhesive to yield a non-tacky, scratch resistant, durable product. The types and levels of monomer greatly affect the performance of the dual cure system. The type and level of photoinitiator plays an even greater role in overall performance. We have found that the dual cure is obtainable with a combination of free radical and cationic photoinitiators, but that the free radical photoinitiator has a greater effect. We have also found that the use of amine functional free radical photoinitiators eliminates the need for a cationic photoinitiator. Too much photoinitiator results in a drier initial surface than desired (poor transfer) and can result in a surface cure that prevents light penetration to the interlayer between the surface and - 12 - the substrate (wetback on transfer film) . Too little photoinitiator results in insufficient cure.
In terms of functional description of substrate to which the adhesive of the present invention can be applied, it has been specifically designed to be applied to the smoother side of banknote paper. We have found that much poorer application and transfer are obtained on the rougher side of the banknote. We have also found that excellent results are obtained when this adhesive is applied to very smooth and/or non absorbent surfaces such as supercalendered papers and plastic films.
While the UV radiation-curable temporarily- pressure-sensitive adhesive compositions according to preferred aspects of the invention as described hereinabove include a pigment (and more particularly a black pigment) to render the composition printable, the compositions of the invention in its broadest aspects need not necessarily include a pigment. Such adhesive compositions without the presence of a pigment would be "clear", and would not be printable, but otherwise have all the desirable characteristics of the UV radiation curable temporarily pressure- sensitive adhesives of the invention as previously described, viz. the adhesives are temporarily pressure-sensitive, and upon exposure to ultraviolet radiation become highly tacky within about 1 second and are curable to a tack-free state within 24 hours to yield a durable scratch-resistant surface. We have attempted to arrive at a UV-curable pressure-sensitive adhesive composition suitable for purposes of the present invention by combining a saturated copolyester with terminal acrylate groups and hydroxyl functionality with polyisocyanates such as the "Mondur"™ products from Mobay or with amines - 13 - such as the "Versamid"™ products from Henkel; however, this resulted in a two-component system. The isocyanate (or the amine) could not be added to the copolyester until just prior to use and it was found that the pot life of the adhesive was very short - probably not more than about 2 hours. It has been discovered that the claimed combination of vinyl ethers with acrylated saturated copolyesters and the other components described herein, yields a single phase, storage-stable, ultra-violet curable adhesive which has a shelf life of at least about 1 year. No reaction between the components of the adhesive composition occurs until exposure to ultraviolet (UV) radiation (or possibly elevated temperatures) . Once the adhesive system is exposed to UV radiation, a pressure-sensitive adhesive is immediately obtained, followed by a decrease in surface tack and hardening of the printed adhesive. With the use of the correct ratio of ingredients, the tack disappears within hours and the material is scratch resistant and durable.
The UV radiation-curable temporarily-pressure- sensitive adhesive according to a preferred embodiment of the present invention has the following properties:
(1) It is black, and is characterized by having an optical density greater than 1.4. The term
"optical density", or opacity, is a measure of imperviousness to light, or the degree of opacity of a medium, expressed as d = log10 Io where Io is the
I intensity of incident light and I is the intensity of the reflected light.
(2) It is printable on a relatively smooth substrate, and in particular, on the smoother side of bank note paper, with good edge definition and uniform ink thickness. - 14 -
(3) It is activated to a tacky state with the use of one or two 300W/inch UV lamps at a linear speed of up to 400 ft./min.
(4) It is capable of attaining a high tack state by ultraviolet radiation initiation in less than 1 second after exposure to ultraviolet radiation.
(5) It is effective as a high tack adhesive at a maximum coating thickness of 12 microns.
(6) It is curable to a tack free state within 24 hours.
(7) It is capable of attaining a final bond strength in less than 200 hours after pressurized transfer at 40 psi for 250 milliseconds under ambient conditions. (8) It is stable to prolonged exposure to varying temperatures below 100°C and varying relative humidities.
(9) When cured, it is resistant to solvents and washing machine laundering, and also resistant to abrasion, folding and crumpling.
The viscosity of the adhesive in its non- activated state ranges from about 3500-5200 cps. at 20°C.
The thin film security device (TFSD) to which reference has been made earlier in this specification is a reflective surface which switches colour when a viewer observes it from different angles. Bank notes with the TFSD are easily identified as genuine but difficult to counterfeit. The TFSD optical coating material is supplied as a very thin releasable layer deposited on a plastic carrier ribbon. The above-described adhesive is used to secure the coating to banknotes in the following manner: /A motif (patch) in adhesive ink, approximately 10 mm by 12 mm, is printed over the - 15 - lithographic background on the face of each banknote. Each note is then exposed to ultra-violet light to begin curing of the adhesive. The plastic carrier ribbon is then forced into contact with the printed adhesive motif as it cures. This application, under appropriate pressure, ensures the instant formation of a positive bond between all three elements: the optical coating, the adhesive, and the banknote. Separation of the plastic ribbon from the banknote releases a portion of the TFSD optical coating onto the banknote surface in the exact image of the printed motif.
BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a schematic drawing of the laminate and substrate before application.
Figure 2 is a schematic drawing of the laminate and substrate after application.
Figure 3 is a plan view of a sheet of banknote paper to which an array of patches of UV radiation curable printable pressure-sensitive adhesive according to the present invention has been applied.
The invention in its various aspects will now be further described, with reference to the accompanying drawings. Referring now to Figs. 1 - 3 of the drawings:
The UV radiation curable pressure-sensitive adhesive (4) is applied to a substrate or a document (5) by an offset gravure printing process or other similar printing application. The adhesive (4) is applied in patches on the document (5) in the shape of the final transferred thin film security device. The substrate or document (5) is preferably banknote paper, but may be other suitable paper carriers which, if desired, could be calendered or plastic coated. The maximum thickness of the adhesive (4) applied is - 16 -
12 μm. Figure 3 illustrates a typical array of patches of the adhesive applied to a sheet of banknote paper. After the adhesive (4) is applied to the substrate (5) it is subjected to ultraviolet radiation. When the adhesive is exposed to ultraviolet light the photoinitiators therein initiate the polymerization of the adhesive.
The polymerization of the adhesive advances it to a tacky state. The adhesive is able to attain a highly tacky state by the action of ultraviolet radiation in less than 1 second after treatment.
The thin film of transparent dielectric material is brought into contact with the adhesive. The dielectric material is one of three layers of a laminate. The three layers of the laminate are: a polyester film of a thickness of 12-25/xm
(i)
- a release coating (2) ; and a stack of dielectric and/or metal layers having a maximum thickness of 1 μm (3) .
The polyester film is comprised of polyethylene terephthalate, a readily available material sold under such trade designations as "Mylar"R, "Hostaphan"™ and "Melinex"™. The release coating may be of any suitable release material known in the art. A suitable thickness of the release coating is about 5 micrometres.
The dielectric material layers (3) are made up of five layers, the outermost layers of which are of zirconia (Zr02) , a central layer also of zirconia, and sandwiched between the outer and innermost zirconia layers are two layers of silica, the total thickness of the combined layers of dielectric material being about 0.8 microns. Alternatively the dielectric material may be comprised of outer layers of metal. - 17 - between which is a layer of silica (Si02) or alumina (A1203) . One of the metal layers is of aluminum, and the other is "Inconel" (trademark), a nickel based, heat- and oxidation-resistant alloy with approximately 13% chromium, 6% iron, and small amounts of manganese, silicon and/or copper.
The thin film security material (TFSM) which is used with a clear adhesive (viz the UV radiation- curable temporarily-pressure-sensitive adhesive composition as previously described in page 2 herein which does not contain any pigment) is that known as metal-dielectric, i.e. that described in the last two sentences of the immediately preceding paragraph.
The aluminum layer in the metal-dielectric TFSM is effectively fully reflective so there is no optical requirement for a pigmented (preferably black) adhesive in this case, as there is for the semi- transparent all-dielectric TFSM (thin film security material) . The layered thin film stack as described above is deposited on a polyethylene terephthalate web (380 mm wide, 0.025 mm thick and 1700 metres long), in a vacuum roll coater manufactured by Ulvac Japan. Zirconia and silica are heated by electron beams of approximately 20 KW power. The deposition thickness is controlled by varying the speed at which material is moved under the electron beam, the beam current, and the sweep patterns of the electron beams. Zirconia and silica are deposited in a single pass of the web through the two deposition chambers in the roll coater.
Thin film security devices and their mode of operation are further described in Baird et al, U.S. Patent No. 3,858,977, dated January 7, 1975, and in the paper entitled "Optically Variable Devices for Use - 18 - on Bank Notes", by J. Rolfe, Proceedings of the International Society for Optical Engineering, SPIE, Vol. 1210, January, 1990, incorporated herein by reference. The transfer process, which takes place at room temperature, brings the dielectric material (3) on the outer surface of the laminate material into pressurized contact with the adhesive patches (4) on the paper. The high tack adhesive (4) is of sufficient strength to exceed the combined release coat (2) holding strength and the dielectric material (3) shear strength. When the laminate material is stripped away, the shape of the thin film security device will shear out of the stack material around the edges of the adhesive patches (4) , leaving the dielectric patch bonded to the paper, with part of the release coat (2) as the exposed surface.
A final bond strength is obtained in less than 200 hours after pressurized transfer at 40 psi for 250 milliseconds. The pressurized transfer can be done with transfer pads on a Thin Film Application and Conversion System (TACS) . Furthermore, the bond is stable after transfer to temperatures varying below 100°C with varying relative humidities. The Thin Film Application and Conversion System (TACS) is a horizontal process machine where stacked bank note sheets are fed in one end and move on a flat horizontal path through each" of the process sections to exit in stacked format at the opposite end. The sheet feeder is a 5000 sheet capacity unit manufactured by Autofeeds London Ltd. , London, England. The sheets are stacked with the longitudinal axis of the individual bank notes parallel to the process axis of the machine. Sheets are stream fed in shingled fashion with the trailing edge of each sheet - 19 - overlapping the leading edge of the following sheet. Sheets are guided against a side lay on the feed board by skewed tapes and fed to a registration stop for transfer to the sheet transport system. The sheet transport system consists of an endless dual chain and sprocket system equipped with mechanical grippers running in a horizontal track mounted below the top surface of a transport table. The bank note sheets are held by the same grippers throughout the application process and move in a "web like" stream with a 6 inch (152 mm) longitudinal pitch spacing between individual bank notes, maintained from sheet to sheet by overlapping leading and trailing edges in shingled fashion. The double thickness caused by this overlapping is accommodated by the resilience of the printing and application rollers.
The printing system uses a gravure offset process to deposit a measured portion of the above-described printable adhesive as a small printed motif on the surface of each bank note. The etched gravure cylinder is charged with ink using a double doctor blade and ink well system manufactured by Inta Roto Co. The gravure cylinder transfers the adhesive ink to a relieved rubber offset cylinder. The offset cylinder deposits the ink directly onto the note sheet as the sheet passes horizontally beneath it through the nip created with the matching impression cylinder mounted beneath the transport table. The offset and impression rollers are relieved to permit passage of the transport system grippers.
The UV curing stage is manufactured by Fusion UV Curing System, Rockville, Maryland, USA. The bank note sheets are passed beneath the curing unit and exit to the TFSM application stage. The adhesive begins curing on exposure to ultra- - 20 - violet (UV) light. The curing time is a function of the duration of the exposure and the intensity of the light source.
Exposure to UV radiation takes place after printing and prior to the arrival of the bank note sheets at the application process. The curing system initiates a photochemical polymerization of the adhesive ink which changes in fractions of a second from a liquid to a highly tacky adhesive. The thin film security material (TFSM), i.e. the laminate as previously described, is applied to the bank note sheets while the adhesive is tacky, and it bonds instantly to form TFSDs. The adhesive dries as the bank note sheets travel to the PAS delivery system.
The ultraviolet radiation is provided by ultraviolet lamps having an output power rating of a minimum of 600 watts per inch transverse to the path of travel of the bank note sheets through the TACS. Suitable lamps for this purpose are two banks of Fusion Systems Corp. "D" lamps or equivalent.
The application stage consists of a plurality of disc shaped rotary application units stacked side by side across the width of the transport table. The outside circumference of each rotary application unit is contoured with raised pressure points similar to gear teeth. The pitch of the pressure points matches the longitudinal pitch spacing of the individual notes on each sheet (6 in.). The application units are matched to an impression cylinder beneath the transport table which creates a nip to provide the required application pressure. The ribbons of TFSM are contained in a plurality of cassette type storage and handling units which are individually mounted within each application unit. As the application - 21 - units rotate in synchronization with the velocity of the bank note sheets moving on the transport table, the ribbons wind in and out of each cassette while being drawn on a circular path covering the pressure points around the circumference of each application unit. The indexing action of each application unit moves a fresh portion of TFSM ribbon over each pressure point as that particular point rotates into contact with an adhesive motif on the bank note sheets passing through the nip.
The TACS forces the laminate or thin film security material (TFSM) ribbon into direct contact with the adhesive motif with sufficient force to cause a complete transfer of the TFSM material to the bank note surface, separates the TFSM ribbon from the surface, and indexes the ribbon to the next section of coating for application. The application device applies a contact force equivalent to the force produced by rolling line contact, the contact force being adjustable in a range of 100 to 1000 N with a mean operating force of 200 N, such as to provide optimum control of adhesive deposition and image density. The transport system delivers the bank note sheets to a stacker unit which is also manufactured by Autofeeds London Ltd. The stacker piles the sheets in stacks of up to 5000 sheets.
The patches of permanently bonded dielectric material provide a security device for which tampering, counterfeiting and copying of the substrate is made more difficult. For example, to photocopy the article with the attached dielectric material will result in an inaccurate copy. The dielectric material reflects coloured light such that the resulting copy will contain areas corresponding to the patches of dielectric material which will be distorted. Any - 22 - attempt to tamper with or remove the dielectric material will damage the article by possibly tearing the document so that successful copying is not possible. As previously indicated, the thin film security device (TFSD) produced in accordance with the present invention, which device incorporates a UV cured adhesive as previously described, must meet a number of requirements so that it is durable in use, that is, so that the thin film security device (TFSD) will last at least as long as any bank note to which it is applied.
The fully cured adhesive (24 hours or more after application on banknotes) with a top layer of thin film material must survive the following mechanical and chemical tests without a significant amount of thin film being removed, the judgement being made visually. The allowable amount of thin film removal is less than 10%. (i) Crumple test - (to evaluate the ability of a TFSD printed bank note to survive folding and creasing) . The thin film adhesive layers are placed on a square piece of bank note 2.25 inches on a side. This piece is rolled into a cylinder, fitted into a metal cylinder, then compressed inside the cylinder with a closely fitting piston using a specified weight as the compression force. The piece is removed from the cylinder, unrolled, moved through 90 degrees and replaced in the cylinder for another compression (a second crumple) . The adhesive-thin film layers must survive four crumples. The apparatus used in this test is commonly known as the IGT Crumple
Tester. Crumpled specimens are compared with existing exemplars from previous tests. - 23 -
(ii) Abrasion Test - to evaluate the ability of a TFSD printed bank note to survive the surface abrasion encountered during circulation:
Using an abrasion testing device similar to the Taber Abraser, a test is performed first on an area of the specimen note not containing a TSFD, to establish the effect of abrasion on intaglio ink. Two abrasion intensities are established; the first corresponding to just noticeable wear of the intaglio ink, the second corresponding to obvious wear. Two TFSD specimens are then subjected to the same treatments using the Taber model 503 Abraser, testing is performed with Taber CS10 abrading wheels with a standard 250 gram loading. The test is run for 100 cycles, after which just noticeable wear of the intaglio print of the bank note has occurred. Abraded specimens are compared to existing exemplars from previous tests, (iii) Laundering Test - to evaluate the ability of the
TSFD printed note to withstand laundering: Using a TFSD specimen secured to an article. of clothing, the specimen is subjected to a normal hot wash laundering cycle using a powerful detergent. Samples are enclosed in shirt pockets and subjected to a normal hot wash cycle: 3/4 cup (approximately 170 ml)
"Tide" detergent with bleach in 41 litres of water (0.4%) at 43°C for 10 minutes, followed by a ten minute rinse in 41 litres of water at 20°C, and a final four minute spin at room temperature. - 24 -
(iv) Chemical Resistance Test to evaluate the ability of a TFSD printed bank note to resist exposure to chemicals:
Specimen notes with a TFSD are immersed in the following chemicals for the times and temperatures specified, and allowed to dry in air. Samples (e) , (f) and (g) were water rinsed to remove the chemical before drying. a) Tetrachloroethylene at 65°C for 2 hours. b) Acetone at 23°C for 2 hours. c) Ethyl alcohol 95% at 65°C for 2 hours. d) Gasoline, lead free, regular grade at 23°C for 2 hours. e) Sodium hydroxide 1% solution, aqueous, at 65°C for 15 minutes. f) Sulphuric acid, 5% solution, aqueous, at 65°C for 2 hours. g) Sodium hypochlorite, 0.6%, at 65°C for 2 hours, h) "Tide"™ detergent, 0.5%, at 65°C for 2 hours, i) Toluene at 65°C for 2 hours. The cured adhesives of the present invention, and the TFSD incorporating same, passes all of the above tests.
Following are examples of the present invention. Adhesive formulations were prepared by mixing together the following ingredients, in the proportions indicated, as expressed in Table 1:
TABLE 1 Ingredients Example 1 Example
2 (a) "Dynacoll A3251" 53.67% - 25 -
54.41%
(b) "Pennco 9B1" 11.78% 11.95%
(c) HBVE 30.22= 30.66%
(d) "Darocur 4043" (a free radical photoinitiator blend) 2.60^,
2.65%
(e) FX 512
(cationic photoinitiator) 1.73=
0.33^
Tests were run on the TACS using the formulations given in Table 1. Viscosities were measured just prior to testing and adjusted with the appropriate vinyl ether diluent where necessary. Each test run was first made with one bank of UV lamps and the machine speed was increased from 120 to 140 to 160 feet per minute; and then a second bank of UV lamps was turned on and the machine speed was decreased from 160 to 140 to 120 feet per minute. Results are shown in Table 2.
TABLE 2
Residual
Transfer Quality Tack Print at speeds (ft.per min.) After
Formulation Quality IB / 2B 5 days
120 140 160
Example 1 Pass A/A A/A A/A No tack
Example 2 Pass A/A A/A A/A No tack - 26 -
T r a n s f e r
Quality
IB = single bank of UV lamps
2B = double bank of UV lamps A = acceptable It has been determined from experiments which have been conducted that the tackier the acrylated polyester oligo er and the higher the content of such oligomer in the formulation the greater the initial tack of the adhesive; and simultaneously, the higher the vinyl ether content, the lower the residual tack of the adhesive. The vinyl ether is an excellent viscosity reducer for the acrylated polyester oligomer. Experiments have also revealed that a chemical environment leading to formation of cations from exposure of the adhesive to UV radiation is necessary, and it is preferred that UV curing of the adhesive be effected at a relative humidity below 51% in the curing chamber.
Furthermore, experiments which have been conducted have shown that the adhesive formulations of the present invention having components (a) - (e) within the ranges of proportions previously set forth herein, including Examples 1 and 2, when applied to banknotes, passed satisfactorily the crumple test, abrasion test, laundering test and chemical resistance test previously described.
While a number of embodiments of the present invention have been described hereinabove, it will be readily apparent to persons skilled in the art that variations and modifications thereof can be made and/or are possible without departing from the spirit and scope of the invention. It is therefore our intention that the present invention not be limited only to what has been specifically described above, but that the invention cover all embodiments as come within the scope of the claims which follow.

Claims

- 27 -THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition comprising:
(a) at least one saturated copolyester having terminal acrylic double bonds and hydroxyl moieties;
(b) at least one polymerizable component selected from the group consisting of acrylic monomers, oligomers thereof, blends of said acrylic monomers and oligomers, and blends of said acrylic monomers or oligomers with a vinyl ether monomer;
(c) at least one vinyl ether monomer, or oligomers thereof, or blends of said vinyl ether monomer and oligomers; and
(d) at least one photoinitiator in a quantity sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation, said adhesive composition being curable to a tack-free state within 24 hours.
2. An ultraviolet radiation curable temporarily pressure-sensitive adhesive composition which comprises:
(a) at least one saturated copolyester with some terminal acrylic double bonds;
(b) at least one polymerizable component selected from the group consisting of acrylic monomers, oligomers thereof, blends of said acrylic monomers and oligomers, and blends of said acrylic monomers or oligomers with a vinyl ether monomer;
(c) at least one vinyl ether monomer, or oligomers thereof, or blends of said vinyl ether monomer and oligomers;
(d) at least one free radical photoinitiator - 28 - and/or photosensitizer; and
(e) at least one cationic photoinitiator; the photoinitiator(s) being present in an amount sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation, said adhesive composition being curable to a tack-free state within 24 hours.
3. A printable ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition comprising:
(a) at least one saturated copolyester having terminal acrylic double bonds and hydroxyl moieties;
(b) at least one pigment dispersed in a liquid selected from the group consisting of an acrylic monomer, a vinyl ether monomer, oligomers thereof, and blends thereof;
(c) at least one vinyl ether monomer, or oligomers thereof, or blends of said vinyl ether monomer and oligomers; (d) at least one photoinitiator in a quantity sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation, and said adhesive being curable to a tack- free state within 24 hours.
4. A printable pigmented ultraviolet radiation- curable temporarily pressure sensitive adhesive composition which comprises:
(a) at least one saturated copolyester with some terminal acrylic double bonds; (b) at least one pigment dispersed in a liquid selected from the group consisting of an acrylic monomer, a vinyl ether monomer, oligomers thereof and blends thereof; - 29 -
(c) at least one vinyl ether monomer, or oligomers thereof, or blends of said vinyl ether monomer and oligomers;
(d) at least one free radical photoinitiator and/or photosensitizer; and
(e) at least one cationic photoinitiator; the photoinitiator(s) being present in an amount sufficient to render the composition tacky within about 1 second after exposure to ultraviolet radiation, said adhesive composition being curable to a tack-free state within 24 hours.
5. A printable ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 3 or claim 4 which has the following properties:
(1) it is printable on a smooth paper substrate with good edge definition and uniform ink thickness;
(2) it is effective as a high tack adhesive at a maximum coating thickness of 12 microns; (3) it is activatable to a tacky state upon exposure to ultraviolet radiation (125 to 700 W/inch) at linear speeds up to 900 ft./min. depending on UV intensity; and
(4) when cured, it is resistant to solvents and washing machine laundering, and is also resistant to abrasion, folding and crumpling.
6. An ultraviolet radiation-curable temporarily pressure-sensitive composition according to any one of claims 1-4 wherein the copolyester comprises polyesters which are saturated in the main chain and have some terminal acrylic double bonds and hydroxyl moieties, said polyesters being further characterized by having an average molecular weight of from 3000 to - 30 -
6000 and a glass transition temperature in the range of from -10°C to -50°C.
7. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 3 wherein the component (b) comprises a carbon black pigment dispersed in an acrylic or vinyl ether monomer or oligomer.
8. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 7 wherein the component (b) consists essentially of a carbon black pigment dispersed in a multifunctional acrylic monomer.
9. An ultraviolet radiation curable temporarily pressure-sensitive adhesive composition according to claim 8 wherein said multifunctional acrylic monomer is trimethylolpropane triacrylate.
10. An ultraviolet radiation curable temporarily pressure-sensitive adhesive composition according to claim 1 or claim 3 wherein the component (c) is 4- hydroxybutyl vinyl ether.
11. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 1 or claim 3 wherein component (a) is present in an amount ranging from 50.0% to 60.0% by weight.
12. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 3 which gives an optical density greater than about 1.4, wherein component, (b) is present in an amount ranging from 11.0% to 15.0% by weight and - 31 - wherein the pigment concentration is present in an amount ranging from 2.2% to 3.0% by weight of the total composition.
13. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 1 or claim 3 wherein component (c) is present in an amount ranging from 25.0% to 35.0% by weight, based on the total composition.
14. Anultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 2 or claim 4 wherein the component (d) is an acetophenone derivative which is 2-hydroxy-2-methyl-l- phenyl propan-1-one, or diethoxyacetophenone, or a blend of said acetophenone derivative with a thioxanthone and an amine benzoate or 2-benzyl-2- (dimethylamino) -1-{4- (4-morpholinyl)phenyl}-1- butanone.
15. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 2 or claim 4 wherein the component (e) is a metallic triarylsulfonium salt of hexafluorophosphate.
16. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 2 or claim 4 wherein component (d) is employed in an amount ranging from 1% to 6% by weight, based on the composition.
17. An ultraviolet radiation-curable temporarily pressure-sensitive adhesive composition according to claim 2 or claim 4 wherein component (e) is employed - 32 - in an amount ranging from 0-2% by weight, based on the composition, and in an amount ranging from 0 - 6% by weight, based on component (c) .
18. A method of providing a substrate with indicia, which comprises:
(1) forming a laminate of
(a) a polyester film having a thickness of 12-25 microns;
(b) a release coating of a thickness of 1-2 microns;
(c) a protective layer 1-2 microns thick; and
(d) a stack of dielectric and/or metal layers having a maximum thickness of 1 micron; (2) providing said substrate with a plurality of areas, each bearing a pressure sensitive adhesive as defined in claim 3 ;
(3) subjecting said substrate containing said adhesive-bearing areas to ultraviolet radiation to render said area tacky;
(4) bringing the outer surface of said stack of dielectric and/or metal layers into pressurized contact with said adhesive-bearing areas on said substrate, thereby adhering said laminate to said area on said substrate; and
(5) stripping said laminate away from the substrate, whereby the dielectric and metal layers are sheared from the release coating and firmly adhere to said areas on said substrate.
19. A method according to claim 18 wherein the substrate is banknote paper.
20. A method according to claim 19 wherein - 33 - method step (2) is effected by offset gravure printing, said printing providing said banknote paper with a pattern of adhesive patches thereon.
21. An article of manufacture comprising: a substrate, to selected areas on the surface of which is permanently bonded a semi- transparent dielectric material, said bonding being by means of a black pressure-sensitive adhesive curable at ambient temperatures by ultraviolet radiation, said adhesive being as defined in claim 3.
22. An article of manufacture according to claim 21 which comprises a pattern of patches of a semi- transparent dielectric material and/or a very thin layer of metal, permanently bonded to banknote paper by means of said pressure-sensitive adhesive.
PCT/CA1993/000519 1992-12-14 1993-12-13 Thin film security device (tfsd) application process and adhesive therefor WO1994013749A1 (en)

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US5747551A (en) * 1994-12-05 1998-05-05 Acheson Industries, Inc. UV curable pressure sensitive adhesive composition
US5968605A (en) * 1997-02-27 1999-10-19 Acushnet Company Electron beam radiation curable inks for game balls, golf balls and the like
WO1999056964A1 (en) * 1998-04-30 1999-11-11 Giesecke & Devrient Gmbh Valuable document with a security element
US6013330A (en) * 1997-02-27 2000-01-11 Acushnet Company Process of forming a print
US6248804B1 (en) 1997-02-27 2001-06-19 Acushnet Company Ultraviolet and or/ visible light curable inks with photoinitiators for game balls, golf balls and the like
JP2001240842A (en) * 2000-02-28 2001-09-04 Nitto Denko Corp Uv-curing type adhesive composition and its adhesive sheets
AT412267B (en) * 2002-03-27 2004-12-27 Hueck Folien Gmbh UV-COVERED SECURITY THREAD
US6887917B2 (en) * 2002-12-30 2005-05-03 3M Innovative Properties Company Curable pressure sensitive adhesive compositions
US6949297B2 (en) 2001-11-02 2005-09-27 3M Innovative Properties Company Hybrid adhesives, articles, and methods
WO2005100026A1 (en) * 2004-04-13 2005-10-27 Man Roland Druckmaschinen Ag Method for applying a film
DE102009001221A1 (en) * 2009-02-27 2010-09-02 Evonik Degussa Gmbh Printing process for the production of individualized electrical and / or electronic structures
US7927703B2 (en) 2003-04-11 2011-04-19 3M Innovative Properties Company Adhesive blends, articles, and methods
US8011411B2 (en) 2004-04-13 2011-09-06 Manroland Ag Pad for embossing device
US8636307B2 (en) 2007-07-20 2014-01-28 Sicpa Holding Sa Intaglio printing inks
WO2016087608A3 (en) * 2014-12-05 2016-10-06 Henkel Ag & Co. Kgaa A reclosable adhesive strip
EP3091043A1 (en) * 2015-05-07 2016-11-09 Henkel AG & Co. KGaA Uv curable adhesives based on acrylic polymers

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Cited By (29)

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Publication number Priority date Publication date Assignee Title
US5747551A (en) * 1994-12-05 1998-05-05 Acheson Industries, Inc. UV curable pressure sensitive adhesive composition
US6248804B1 (en) 1997-02-27 2001-06-19 Acushnet Company Ultraviolet and or/ visible light curable inks with photoinitiators for game balls, golf balls and the like
US6001898A (en) * 1997-02-27 1999-12-14 Acushnet Company Electron beam radiation curable inks for game balls, golf balls and the like
US6013330A (en) * 1997-02-27 2000-01-11 Acushnet Company Process of forming a print
US6099415A (en) * 1997-02-27 2000-08-08 Acushnet Company Ultraviolet radiation curable inks for game balls, golf balls and the like
US5968605A (en) * 1997-02-27 1999-10-19 Acushnet Company Electron beam radiation curable inks for game balls, golf balls and the like
WO1999056964A1 (en) * 1998-04-30 1999-11-11 Giesecke & Devrient Gmbh Valuable document with a security element
US6688221B1 (en) 1998-04-30 2004-02-10 Giesecke & Devrient Gmbh Valuable document with a security element
US6874414B2 (en) 1998-04-30 2005-04-05 Giesecke & Devrient Gmbh Method and apparatus for screen printing
JP2001240842A (en) * 2000-02-28 2001-09-04 Nitto Denko Corp Uv-curing type adhesive composition and its adhesive sheets
US6949297B2 (en) 2001-11-02 2005-09-27 3M Innovative Properties Company Hybrid adhesives, articles, and methods
AT412267B (en) * 2002-03-27 2004-12-27 Hueck Folien Gmbh UV-COVERED SECURITY THREAD
US6887917B2 (en) * 2002-12-30 2005-05-03 3M Innovative Properties Company Curable pressure sensitive adhesive compositions
US7927703B2 (en) 2003-04-11 2011-04-19 3M Innovative Properties Company Adhesive blends, articles, and methods
US8960087B2 (en) 2004-04-13 2015-02-24 manroland sheetfed GmbH Method for applying a film
WO2005100026A1 (en) * 2004-04-13 2005-10-27 Man Roland Druckmaschinen Ag Method for applying a film
US8011411B2 (en) 2004-04-13 2011-09-06 Manroland Ag Pad for embossing device
US8087440B2 (en) 2004-04-13 2012-01-03 Manroland Ag Embossing device
US8201605B2 (en) 2004-04-13 2012-06-19 Manroland Druckmaschinen AG Printing machine comprising an embossing device
US8834659B2 (en) 2004-04-13 2014-09-16 manroland sheetfed GmbH Embossing device
US8636307B2 (en) 2007-07-20 2014-01-28 Sicpa Holding Sa Intaglio printing inks
DE102009001221A1 (en) * 2009-02-27 2010-09-02 Evonik Degussa Gmbh Printing process for the production of individualized electrical and / or electronic structures
WO2016087608A3 (en) * 2014-12-05 2016-10-06 Henkel Ag & Co. Kgaa A reclosable adhesive strip
CN107207916A (en) * 2014-12-05 2017-09-26 汉高股份有限公司 A kind of reclosable adhesive tape
JP2018507266A (en) * 2014-12-05 2018-03-15 ヘンケル・アクチェンゲゼルシャフト・ウント・コムパニー・コマンディットゲゼルシャフト・アウフ・アクチェンＨｅｎｋｅｌ ＡＧ ＆ Ｃｏ． ＫＧａＡ Resealable adhesive strip
EP3091043A1 (en) * 2015-05-07 2016-11-09 Henkel AG & Co. KGaA Uv curable adhesives based on acrylic polymers
WO2016177861A1 (en) * 2015-05-07 2016-11-10 Henkel Ag & Co. Kgaa Uv curable adhesives based on acrylic polymers
JP2018520215A (en) * 2015-05-07 2018-07-26 ヘンケル・アクチェンゲゼルシャフト・ウント・コムパニー・コマンディットゲゼルシャフト・アウフ・アクチェンＨｅｎｋｅｌ ＡＧ ＆ Ｃｏ． ＫＧａＡ UV curable adhesives based on acrylic polymers
US10711166B2 (en) 2015-05-07 2020-07-14 Henkel Ag & Co. Kgaa UV curable adhesives based on acrylic polymers

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