Classifications

• • 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
• • 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
  • B41M3/008—Sequential or multiple printing, e.g. on previously printed background; Mirror printing; Recto-verso printing; using a combination of different printing techniques; Printing of patterns visible in reflection and by transparency; by superposing printed artifacts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/34—Multicolour thermography
• • 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
  • B41M3/142—Security printing using chemical colour-formers or chemical reactions, e.g. leuco-dye/acid, photochromes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/34—Multicolour thermography
  • B41M5/345—Multicolour thermography by thermal transfer of dyes or pigments
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/382—Contact thermal transfer or sublimation processes
  • B41M5/38207—Contact thermal transfer or sublimation processes characterised by aspects not provided for in groups B41M5/385 - B41M5/395

Definitions

• This invention relates to colour imaging of security document precursors with the aim of producing security documents that are difficult to falsify.
• packaging material of pharmaceuticals is laser marked to enable a consumer to verify the genuineness of a product.
• Laser marked security cards are widely used for various applications such as identification purposes (ID cards) and financial transfers (credit cards).
• ID cards typically consist of a laminated structure consisting of various papers or plastic laminates and layers wherein some of them may carry alphanumeric data and a picture of the card holder.
• So called 'smart cards' can also store digital information by including an electronic chip in the card body.
• laser marking and laser engraving.
• literature laser engraving is often incorrectly used for laser marking.
• a colour change is observed by local heating of material in the bulk of the article, while in laser engraving material is removed by ablation.
• laser marking employed in the manufacture of security documents consists solely of a "black” laser marking method via the carbonization of a polymer, usually polycarbonate as disclosed in e.g. EP 2181858 A (AGFA) .
• AGFA EP 2181858 A
• US 4720449 discloses a thermal imaging method for
• the laser beams may have different wavelengths in a range above 700nm with at least about 60 nm apart so that each imaging layer having a different infrared absorber may be exposed separately to convert a colourless triarylmethane compound into a coloured form.
• WO 2009/106036 A discloses a method for
• a security and value document containing a polymer laminate formed from a basic polymer laminate and a polymer coating.
• the polymer coating has a printable substrate layer that can absorb a diffusible ink printed by thermosublimation or inkjet printing.
• the polymer laminate can be laser marked through pyrolysis (carbonization).
• EP 2181851 A discloses that a dye image in a dye diffusion
• transfer image receptor layer comprising a polymeric mordant could be laser engraved, while no laser engraving appeared to be possible with dye images obtained with other imaging techniques such as thermal dye sublimation and inkjet.
• EP 2332738 A discloses the laser perforation of a security
• document precursor with two or more holes near a perimeter edge surface of the precursor, wherein at least one of the holes is filled with a coloured material by e.g. inkjet ink printing, so that the coloured material is visible from a direction perpendicular on the perimeter edge surface.
• a coloured material e.g. inkjet ink printing
• US 2009201321 A discloses a system integrating a digital press with an ink jet device to form a security document including a xerographic portion and an invisible inkjet ink portion, in order to produce documents in a continuous inline process.
• embodiments of the present invention provide a method of producing a security document including the steps of a) producing a first part of a colour image by colour laser marking a security document precursor; and b) producing a second part of the colour image by a second imaging technique different from laser marking.
• the present invention provides a method wherein two colour imaging
• Another advantage is that by using different imaging techniques that
• colours which are difficult to reproduce by one imaging technique can be reproduced by the second imaging technique.
• spot colours like Coca ColaTM red or IBMTM blue can be easily reproduced by UV curable inkjet printing in the second part of the colour image, while this may be a challenge in reproducing them by colour laser marking.
• Figure 1.a shows a cross section of an embodiment of a colour laser
• Figure 1.b shows a cross section of the end result, i.e. a laser markable precursor 13 obtained by the lamination in Figure 1.a.
• FIG 2 shows a cross section of a security document 21 including, in order, a core support 24, a colour laser markable layer 26, a transparent polymeric support 25, a colour laser markable layer 27, and a polymeric overlay 28.
• the security document 21 contains colour laser markings 23 in the colour laser markable layers 26 and 27, and contains UV curable inkjet ink markings 22.
• the colour laser markings 23 and the UV curable inkjet ink markings 22 together form a single colour image.
• Figure 3 shows a symmetrical security document precursor including on both sides of an opaque core 32, a colour laser markable layer 33, a transparent polymeric support 34, a colour laser markable layer 35, and a polymeric overlay 36.
• Figure 4 shows the interlamination of a hologram 47 between a polymeric overlay 41 and a security laminate 42 including two colour laser markable layers 45 and 46 on a transparent polymeric support 44, all being laminated onto a core support 43.
• polymeric support and "foil”, as used herein, mean a self- supporting polymer-based sheet, which may be associated with one or more adhesion layers e.g. subbing layers. Supports and foils are usually manufactured through extrusion.
• layer is considered not to be self-supporting and is manufactured by coating it on a (polymeric) support or foil.
• leuco dye refers to compounds which can
• PET is an abbreviation for polyethylene terephthalate.
• PETG is an abbreviation for polyethylene terephthalate glycol, the glycol indicating glycol modifiers which are incorporated to minimize brittleness and premature aging that occur if unmodified amorphous polyethylene terephthalate (APET) would be used in the production of cards.
• APET amorphous polyethylene terephthalate
• PET-C is an abbreviation for crystalline PET, i.e. a biaxially stretched polyethylene terephthalate. Such a polyethylene terephthalate support has excellent properties of dimensional stability.
• alkyl means all variants possible for each number of carbon atoms in the alkyl group i.e. methyl, ethyl, for three carbon atoms: n-propyl and isopropyl; for four carbon atoms: n-butyl, 1 -isobutyl, 2-isobutyl and tertiary-butyl; for five carbon atoms: n-pentyl, 1 , 1-dimethyl-propyl, 2,2- dimethylpropyl and 2-methyl-butyl, etc.
• a substituted or unsubstituted alkyl group is preferably a Ci to C6-alkyl group.
• a substituted or unsubstituted alkenyl group is preferably a C2 to C6-alkenyl group.
• a substituted or unsubstituted alkynyl group is preferably a C2 to C6-alkynyl group.
• a substituted or unsubstituted aralkyl group is preferably phenyl group or naphthyl group including one, two, three or more Ci to C6-alkyl groups.
• a substituted or unsubstituted alkaryl group is preferably a Ci to C6-alkyl group including an aryl group, preferably a phenyl group or naphthyl group.
• a substituted or unsubstituted aryl group is preferably a substituted or unsubstituted phenyl group or naphthyl group.
• a cyclic group includes at least one ring structure and may be a
• a heterocyclic group is a cyclic group that has atoms of at least two
• heterocyclic groups are homocyclic groups, the ring structures of which are made of carbon only. Unless otherwise specified a substituted or unsubstituted heterocyclic group is preferably a five- or six-membered ring substituted by one, two, three or four heteroatoms, preferably selected from oxygen atoms, nitrogen atoms, sulphur atoms, selenium atoms or combinations thereof.
• An alicyclic group is a non-aromatic homocyclic group wherein the ring atoms consist of carbon atoms.
• heteroaryl group means a monocyclic- or polycyclic aromatic ring comprising carbon atoms and one or more heteroatoms in the ring structure, preferably, 1 to 4 heteroatoms, independently selected from nitrogen, oxygen, selenium and sulphur.
• heteroaryl groups include, but are not limited to, pyridinyl, pyridazinyl, pyrimidyl, pyrazyl, triazinyl, pyrrolyl, pyrazolyl, imidazolyl, (1 ,2,3,)- and (1 ,2,4)- triazolyl, pyrazinyl, pyrimidinyl, tetrazolyl, furyl, thienyl, isoxazolyl, thiazolyl, isoxazolyl, and oxazolyl.
• a heteroaryl group can be unsubstituted or substituted with one, two or more suitable substituents.
• a heteroaryl group is a monocyclic ring, wherein the ring comprises 1 to 5 carbon atoms and 1 to 4 heteroatoms.
• substituted in e.g. substituted alkyl group means that the alkyl group may be substituted by other atoms than the atoms normally present in such a group, i.e. carbon and hydrogen.
• a substituted alkyl group may include a halogen atom or a thiol group.
• An unsubstituted alkyl group contains only carbon and hydrogen atoms.
• substituted alkyl group Unless otherwise specified a substituted alkyl group, a substituted alkenyl group, a substituted alkynyl group, a substituted aralkyl group, a
• substituted alkaryl group, a substituted aryl, a substituted heteroaryl and a substituted heterocyclic group are preferably substituted by one or more substituents selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, 1 -isobutyl, 2-isobutyl and tertiary-butyl, ester, amide, ether, thioether, ketone, aldehyde, sulfoxide, sulfone, sulfonate ester, sulphonamide, -CI, -Br, -I, -OH, -SH, -CN and -NO 2 .
• a preferred embodiment of the present invention is a method of producing a security document including the steps of: a) producing a first part of a colour image by colour laser marking a security document precursor; and b) producing a second part of the colour image by a second imaging technique different from laser marking.
• the second part of the colour image includes one or more chromatic colours.
• Achromatic colours are white, black and grey, i.e. having no particular hue.
• the first part of the colour image is made by colour laser marking two colour laser markable layers producing different colours, more preferably one colour laser markable layer producing a cyan or blue colour and the other colour laser markable layer producing a magenta or red colour, while the second part of the colour image is made by a second imaging technique providing the complementary colour yellow or green, more preferably yellow.
• the integration of the three colours e.g. cyan, magenta and yellow, provides a full colour image of chromatic colours.
• the one or more chromatic colours in the second part of the colour image may include a spot colour.
• a spot colour is a custom colour, e.g. Coca ColaTM red or IBMTM blue, which may be very difficult to match using the colour laser marking imaging technique.
• spot colours can be applied much more easily by using specific colour dyes or pigments by e.g. inkjet printing or thermosublimation printing.
• the imaging technique used for producing the second part of the colour image is an imaging technique different from laser marking. Using a laser for the second part of the colour image makes falsification much easier, since the alignment of the first and second parts of the colour image requires only a minor adaptation of laser optics. By using a different imaging technique for the second part of the colour image, the exact alignment of the first and second parts of the colour image becomes much more difficult. In principle, a forger only has one opportunity to falsify a security document, thus by limiting the number of trials for aligning the first and second parts of the colour image the security of a security document is enhanced.
• the second imaging technique is a technique allowing variable data to be applied.
• a preferred second imaging technique allowing variable data printing is inkjet printing, more preferably UV curable inkjet printing. UV curable inkjet printing does not require the presence of a specific ink- absorbing layer on the polymeric overlay contrary to aqueous or solvent inkjet printing.
• Other preferred second imaging techniques include xerography and particularly thermosublimation printing.
• the ZebraTM P310i is a reliable security card printer for applying single side thermosublimation or thermotransfer prints in monochrome or four colors.
• the security document precursors includes preferably one or two colour laser markable layers on a transparent polymeric support, more preferably on the same transparent polymeric support wherein one colour laser markable layer is present on one side of the transparent polymeric support and the other colour laser markable layer is present on the opposite side.
• the two colour laser markable layers wherein the colour laser markable layer closest to the core support includes an infrared dye IR-1 with a maximum absorption in the infrared region at the wavelength A m ax(IR-1 ), while the other colour laser markable layer includes an infrared dye IR-2 with a maximum absorption in the infrared region at the wavelength A m ax(IR-2)
• Amax(IR) is the wavelength of the absorption maximum in the infrared
• the A ma x(IR-1 ) and A ma x(IR-2) are preferably measured by absorption spectroscopy on a coated layer, since the value of A m ax may differ somewhat, although usually no more than 10 nm, on the type of solvent used in an infrared dye solution.
• the infrared dye IR-1 has an absorption
• a security document is obtained after colour laser marking and imaging a security document precursor with the second imaging technique.
• the security document is preferably selected from the group consisting of a passport, a personal identification card and a product identification document.
• the security document has a format as
• the color laser marked article is a security document including electronic circuitry, more preferably the electronic circuitry includes a RFID chip with an antenna and/or a contact chip. Inclusion of electronic circuitry makes forgery more difficult.
• the security document precursor may include three or more color laser markable layers for increasing the color gamut.
• two color laser markable layers each include a different leuco dye for forming a color having an absorption maximum Amax (VIS-1 ) and Amax (VIS-2) in the visible spectrum of 400 nm to 700 nm.
• Amax absorption maximum
• VIS-2 absorption maximum
• VIS-2 absorption maximum
• VIS-2 absorption maximum
• the security document precursor is also capable of producing a black color.
• the black color is produced by using the
• infrared laser preferably the infrared laser used for the color laser markable layer capable of forming a cyan or blue color image on laser marking, in different laser operation modes as disclosed by WO
• the advantage of using the infrared laser of the color laser markable layer forming a cyan or blue color image is that a neutral black color is formed which is more appealing than a brownish black color which would be formed on using the infrared laser for the color laser markable layer capable of forming e.g. a yellow or a magenta color image on laser marking.
• the security document precursor [0057] In a more preferred embodiment, the security document precursor
• the laser markable polymeric support for generating a black color may be an additional foil or laminate, but is preferably the (opaque) core support or a transparent polymeric support of the color laser markable layer.
• the security document precursor is preferably to a large degree
• symmetrical or more preferably completely symmetrical are present on both sides of the core support.
• the advantage thereof is that curl of the security document precursor is minimized.
• An asymmetrical security document precursor often exhibits curl and usually requires a thermal relaxation in order to obtain e.g. a flat asymmetrical ID card.
• the security document precursor includes one or more biaxially stretched polyester films, more preferably the outermost films or polymeric overlays of the security document precursor are biaxially stretched polyester films.
• biaxially stretched polyester preferably biaxially stretched polyethylene terephthalate overlays
• the one or more colour laser markable layers for producing the first part of the colour image by colour laser marking are adequately protected against falsification due to being located between two biaxially stretched polyester films.
• the color laser markable layers preferably contain an infrared dye for the conversion of electromagnetic radiation into heat when the color laser markable layer is exposed by the infrared laser.
• a color laser markable layer includes preferably at least an infrared dye, a polymeric binder and a substantially colorless compound, preferably a leuco dye.
• Color is produced in the color laser markable layer by a chemical reaction converting the substantially colorless compound into a dye, wherein the chemical reaction is triggered by local heating with an infrared laser having an emission wavelength matching the absorption maximum of the infrared dye.
• a laser emission wavelength is selected within a range of ⁇ 30 nm of the absorption maximum in the infrared region A m ax(IR) of the infrared dye.
• the infrared dye not only delivers the heat for the color forming action, but also has the advantage that there is no or minimal absorption in the visible spectrum and thus there is no or minimal interference with the color formed by the laser markable layer. This makes a pure white background possible, which is often desired in a security document.
• the color laser markable layers can be coated onto a support by any method.
• the laser markable layer is coated with a slide hopper coater or a curtain coater, more preferably coated onto a transparent polymeric support including a subbing layer.
• the dry thickness of the color laser markable layer is preferably between 4 and 40 g/m 2 , more preferably between 5 and 25 g/m 2 , and most preferably between 6 and 15 g/m 2 .
• the color laser markable layers include different infrared dyes and color forming compounds.
• the infrared dyes differ in wavelength of maximum absorption A m ax so that they can be addressed by different infrared lasers with corresponding emission wavelengths causing color formation only in the color laser markable layer of the addressed infrared dye.
• the color laser marked article preferably contains two color laser markable layers having different infrared dyes and different leuco dyes on the same side of a core support for producing a multi-colored article.
• the different infrared dyes have an absorption maximum in the infrared region which differs preferably by at least 60 nm, more preferably at least 80 nm and most preferably at least 100 nm.
• Suitable examples of infrared dyes include, but are not limited to,
• polymethyl indoliums metal complex IR dyes, indocyanine green, polymethine dyes, croconium dyes, cyanine dyes, merocyanine dyes, squarylium dyes, chalcogenopyryloarylidene dyes, metal thiolate complex dyes, bis(chalcogenopyrylo)polymethine dyes, oxyindolizine dyes, bis(aminoaryl)polymethine dyes, indolizine dyes, pyrylium dyes, quinoid dyes, quinone dyes, phthalocyanine dyes, naphthalocyanine dyes, azo dyes, (metalized) azomethine dyes and combinations thereof.
• the infrared dye is preferably present in the color laser markable layer in an amount of 0.01 to 1.0 g/m 2 , more preferably in an amount of 0.02 to 0.5 g/m 2 and most preferably in an amount of 0.05 to 0.2 g/m 2 .
• An amount of less than 0.01 g/m 2 requires a too high laser power and an amount of more than 0.5 g/m 2 may result in background discoloration.
• the infrared dye for the colour laser markable closest to the core support is selected from the group consisting of quinoline dyes, indolenine dyes, especially a benzo[cd]indoline dye.
• Such infrared dyes preferably absorb above 1000 nm.
• a particular preferred infrared dye is 5-[2,5-bis[2-[1-(1 - methylbutyl)benz[cd]indol-2(1 H)-ylidene]ethylidene]cyclopentylidene]-1 - butyl-3-(2-methoxy-1 -methylethyl)- 2,4,6(1 H,3H,5H)-pyrimidinetrione (CASRN 223717-84-8), which has an absorption maximum Amax of 1052 nm making it very suitable for a Nd-YAG laser having an emission wavelength of 1064 nm.
• the infrared dye for the outermost colour laser markable layer is selected from the group consisting of quinoline dyes, indolenine dyes, especially benzo[e]indolenine dyes, and
• Such infrared dyes preferably absorb below 1000 nm.
• the color laser markable layer includes a polymeric binder.
• a polymeric binder There is no real limitation on the type of polymeric binder for so far it allows color formation.
• the laser markable layer preferably includes a polymeric binder comprising vinyl acetate and at least 85 wt% of vinyl chloride based on the total weight of the binder.
• Particularly preferred polymeric binders are disclosed in EP 24631 10 A (AGFA) .
• the polymeric binder in the laser markable layer is preferably a copolymer including at least 85 wt% of a vinyl chloride and 1 wt% to 15 wt% of vinyl acetate, more preferably a copolymer including at least 90 wt% of a vinyl chloride and 1 wt% to 10 wt% of vinyl acetate with all wt% based on the total weight of the binder.
• the polymeric binder includes at least 4 wt% of vinyl acetate based on the total weight of the binder.
• the advantage of having at least 4 wt% of vinyl acetate in the polymeric binder is that the solubility of the polymeric binder is drastically improved in preferred coating solvents, such as methyl ethyl ketone.
• the polymeric binder consists of vinyl chloride and vinyl acetate.
• the color laser marked article includes a laser markable layer for
• the polymeric binder is preferably selected from polycarbonate (PC), polybutylene terephthalate (PBT), polyvinyl chloride (PVC), polystyrene (PS) and copolymers thereof, such as e.g. aromatic polyester-carbonate, styrene acrylonitrile and acrylonitrile butadiene styrene (ABS).
• PC polycarbonate
• PBT polybutylene terephthalate
• PVC polyvinyl chloride
• PS polystyrene
• ABS acrylonitrile butadiene styrene
• the polymeric binder is preferably present in the color laser markable
• a leuco dye is a compound which changes from essentially colorless to colored when heated, e.g. by laser marking.
• a number of classes of leuco dyes are preferred for the laser markable layer of the present invention, for example: azines such as oxazines, diazines and thiazines;
• triarylmethanes such as fluoresceins, rhodamines and rhodols; ketazines; barbituric acid leuco dyes and thiobarbituric acid leuco dyes.
• the leuco dye is preferably present in the color laser markable layer in an amount of 0.5 to 5.0 g/m 2 , more preferably in an amount of 1.0 to 3.0 g/m 2 .
• reaction mechanisms and leuco dyes are suitable to form a colored dye.
• reaction mechanism can be represented by:
• POLAROID which discloses a thermal imaging method for forming color images by the irreversible unimolecular fragmentation of one or more thermally unstable carbamate moieties of an organic compound to give a visually discernible color shift from colorless to colored.
• the fragmentation of a leuco dye may be a two-step reaction mechanism represented by:
• the fragmentation of a leuco dye may be catalyzed or amplified by acids and acid generating agents.
• the leuco dyes G-(1 ) to G-(17) disclosed by US 6100009 (FUJI) are catalyzed or amplified by polymeric acid generating agents based on A-(1 ) to A-(52), which are also suitable as acid generating agents in the present invention.
• reaction mechanism can be represented by:
• a preferred H-donor-FG compound includes an ester group as part of its chemical structure (the rest of the compound is represented by the group T) which by laser heating forms a carboxylic acid group:
• a more preferred H-donor-precursor includes a carbonate group, e.g. a tBOC group, as part of its chemical structure (the rest of the compound is represented by the group T) which by laser heating forms a phenol group:
• Preferred carbonate groups are given on page 8 of EP 605149 A (JUJO PAPER) .
• the H-donor-FG compound contains 2 carbonate groups.
• H-donor-FG compound is:
• the fragmentation of the H-donor-FG compound above also leads to the formation of a compound having a melting temperature lower than room temperature (20°C).
• the formation of such a compound can be used as an additional security feature.
• the compound having a melting temperature lower than room temperature may disturb a second laser marking (falsification of a security document) by the formation of visible blisters.
• reaction mechanism can be represented by:
• a preferred H-donor-RG compound is capable of forming a compound having an allyl substituted phenol group as part of its chemical structure rest of the compound is represented by the group T) by laser heating
• Preferred H-donor-RG compounds include 4,4'-diallyloxy diphenylsulfone whereof the synthesis is disclosed by EP 1452334 A (RICOH) .
• the color formation according to the mechanisms 2 and 3 above are two- component reactions involving a leuco dye and a hydrogen donor- precursor, i.e. a ⁇ -donor-FG compound' or ⁇ -donor-RG compound' , while the first reaction mechanism is an one-component reaction.
• the advantage of using a two-component reaction for the color formation is that the stability, especially the shelf-life stability, can be enhanced.
• the probability of undesired color formation due to environment heating is decreased by going from a single step reaction to a two step reaction involving the formation of the H-donor followed by a reaction of the formed H-donor with the leuco dye.
• the preferred color formation mechanism is the protonation of a leuco dye after fragmentation of the H-donor since it includes both advantages of the blister formation security feature and the enhanced shelf-life stability.
• a combination is used of 4,4'-Bis(tert-butoxycarbonyloxy)diphenylsulfone (CASRN 129104- 70-7) as the H-donor-FG compound with the leuco dye crystal violet lactone (CASRN 1552-42-7) for producing a blue color.
• the cyan color forming compound has a structure according to Formula CCFC:
• magenta color the magenta color forming compound has a structure according to Formula MCFC:
• R, R', R" are independently selected from the group consisting of hydrogen, a linear alkyl group, a branched alkyl group, an aryl and aralkyl group; or R' and R" are linked to form a heterocyclic ring.
• the magenta color forming compound has a structure according to Formula MCFC, the R, R', R" may independently represent a linear alkyl group, a branched alkyl group, an aryl or an aralkyl group substituted by at least one functional group containing an oxygen atom, a sulphur atom or a nitrogen atom.
• magenta color forming compounds include the
• magenta color forming compound has a structure according to Formula MCFC2:
• the red color forming compound has a structure according to Formula RCFC:
• the yellow color forming compound has a structure according to Formula YCFC:
• R, R' are independently selected from a group consisting of a linear alkyl group, a branched alkyl group, an aryl and aralkyl group.
• the yellow color forming compound has a structure according to Formula YCFC, wherein R and R' independently represent a linear alkyl group, a branched alkyl group, an aryl or an aralkyl group substituted by at least one functional group containing an oxygen atom, a sulphur atom or a nitrogen atom.
• a particularly preferred yellow color forming compound is the compound according to Formula YCFC wherein both R and R' are methyl.
• the leuco dye is preferably present in the laser markable layer in an
• the fragmentation of a leuco dye in a color laser markable layer according to the present invention may be catalyzed or amplified by acids and acid generating agents.
• Suitable thermal acid generating agents may be the polymeric acid
• Suitable non-polymeric acid generating agents are, for example, the
• the thermal acid generating agent is preferably present in the amount of 1 to 20 wt%, more preferably 5 to 15 wt% based on the total dry weight of the laser markable layer.
• the color laser markable layer preferably the outermost color laser
• markable layer may include at least one stabilizer, preferably a UV stabilizer.
• Suitable commercially available stabilizers include 6-O-palmitoyl-L- ascorbic acid (CASRN 137-66-6) from BASF; TOCOBLENDTM
• Particularly preferred stabilizers include a phenol stabilizer sterically hindered by a ring containing three nitrogen atoms represented by
• R1 to R7 is each independently selected from the group consisting of hydrogen, an alkyl group containing 1 to 12 carbon atoms and an alkoxy group containing 1 to 12 carbon atoms;
• R8 represents hydrogen or a halogen atom
• R9 and R10 is each independently selected from the group consisting of hydrogen, an alkyl group containing 1 to 6 carbon atoms and an aryl group containing 1 to 12 carbon atoms;
• R1 1 to R14 is each independently selected from the group consisting of an alkyl group containing 1 to 6 carbon atoms.
• R1 to R7 is each independently selected from the group consisting of hydrogen, an alkyl group containing 1 to 8 carbon atoms, more preferably an alkyl group containing 1 to 6 carbon atoms, and an alkoxy group containing 1 to 8 carbon atoms, more preferably an alkoxy group containing 1 to 6 carbon atoms.
• R9 and R10 is each independently selected from the group consisting of hydrogen, an alkyl group containing 1 to 8 carbon atoms, more preferably an alkyl group containing 1 to 6 carbon atoms, and an aryl group containing 1 to 12 carbon atoms, more preferably an alkyl group containing 1 to 10 carbon atoms.
• R5 and R6 both represent hydrogen.
• R1 1 to R14 all represent methyl
• R9 and/or R10 represent methyl or phenyl.
• R8 represents a chlorine atom.
• R9 and/or R10 represent a phenyl substituted by an alkyl group or a napthyl group.
• the color laser markable laminate includes a phenol stabilizer sterically hindered by a ring containing three nitrogen atoms and is selected from the group consisting of IS-1 to IS-4 shown here below.
• the stabilizer is preferably present in a colour laser markable layer, but may also be present in another layer, for example, an outer layer.
• An outer layer is a layer more distant from the (opaque) core support than the laser markable layers on the same side of the opaque core support.
• one or more organic solvents may be used.
• the use of an organic solvent facilitates the dissolution of the polymeric binder and specific ingredients such as the infrared dye.
• a preferred organic solvent is methylethylketone (MEK) because it combines a high solubilizing power for a wide range of ingredients and it provides, on coating the color laser markable layer, a good compromise between the fast drying of the layer and the danger of fire or explosion thereby allowing high coating speeds.
• MEK methylethylketone
• the color laser markable layers are coated on a transparent polymeric support. If a polymeric foil, e.g. the polymeric overlay, is located between the color laser markable layer and the infrared laser for laser marking it, then the polymeric foil is transparent for the light of the infrared lasers in at least that area used for laser marking.
• the polymeric foils used a support or overlay are also transparent for visual light so that the color formed in the color laser markable layers can be well observed.
• the polymeric support for a laser markable layer is preferably a
• transparent (bi)axially stretched polymeric support more preferably a transparent (bi)axially stretched polyester support, and most preferably a transparent (bi)axially stretched polyethylene terephthalate support.
• the transparent polymeric overlay is preferably selected from the group consisting of an axially stretched polyethylene terephthalate support, a biaxially stretched polyethylene terephthalate support, an axially stretched polyethylene naphthalate support and a biaxially stretched polyethylene naphthalate support.
• both the transparent polymeric support for the colour laser markable layers and the outermost polymeric foil are a biaxially stretched polyethylene terephthalate support.
• the color laser markable layer may be coated directly on the polymeric support or on a subbing layer provided on the polymeric support for improving adhesion of the laser markable layer, thereby making
• Suitable polymeric supports and overlays include cellulose acetate
• polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyamides, polycarbonates, polyimides, polyolefins, polyvinylchlorides, polyvinylacetals, polyethers and polysulphonamides.
• the transparent polymeric overlay(s) is a biaxially stretched polyethylene terephthalate foil (PET-C foil) which is very durable and resistant to mechanical influences (flexion, torsion, scratches), chemical substances, moisture and temperature ranges. This is especially useful for security documents such as identification cards and credit cards for which the average daily usage has augmented
• PET-C foil biaxially stretched polyethylene terephthalate foil
• PC polycarbonate
• the transparent polymeric support and overlays are preferably a single component extrudate, but may also be co-extrudate.
• Polyester supports and especially polyethylene terephthalate supports are preferred because of their excellent properties of dimensional stability.
• a subbing layer is preferably employed to improve the bonding of layers, foils and/or laminates to the support.
• PET-C foils and supports are well-known to a person skilled in the art of preparing suitable supports for silver halide
• GB 811066 (ICI) teaches a process to produce biaxially oriented polyethylene terephthalate foils and supports.
• the polyethylene terephthalate is preferably biaxially stretched with a stretching factor of at least 2.0, more preferably at least 3.0 and most preferably a stretching factor of about 3.5.
• the temperature used during stretching is preferably about 160°C.
• the core support may be a transparent or translucent support, but is
• an opaque core support more preferably having a white or a pastel color, most preferably a white color, for allowing easily readable information and viewable color images.
• the advantage of an opaque white core support is also that a color image is more appealing since colors usually are more vibrant with a white background.
• Preferred opaque white core supports include resin coated paper
• supports such as polyethylene coated paper and polypropylene coated paper, and synthetic paper supports such as SynapsTM synthetic paper of Agfa-Gevaert NV.
• polystyrene foams include opaque white polyesters and extrusion blends of polyethylene terephthalate and polypropylene. Also TeslinTM may be used as support.
• a white opacifying layer can be coated onto a transparent polymeric support, such as those disclosed above.
• the opacifying layer preferably contains a white pigment with a refractive index greater than 1.60, preferably greater than 2.00, and most preferably greater than 2.60.
• the white pigments may be employed singly or in combination. Suitable white pigments include C.I. Pigment White 1 , 3, 4, 5, 6, 7, 10, 1 1 , 12, 14, 17, 18, 19, 21 , 24, 25, 27, 28 and 32.
• Preferably titanium dioxide is used as pigment with a refractive index greater than 1.60. Titanium oxide occurs in the crystalline forms of anatase type, rutile type and brookite type.
• the rutile type is preferred because it has a very high refractive index, exhibiting a high covering power.
• polymeric overlays may be provided with one or more subbing layers. This has the advantage that the adhesion between a layer and the support is improved.
• Useful subbing layers for this purpose are well known in the photographic art and include, for example, polymers of vinylidene chloride such as vinylidene chloride/acrylonitrile/acrylic acid terpolymers or vinylidene chloride/methyl acrylate/itaconic acid terpolymers.
• subbing layers are well-known in the art of manufacturing polyester supports for silver halide photographic films.
• preparation of such subbing layers is disclosed in US 3649336 (AGFA) , GB 1441591 (AGFA) and EP 2374602 A (AGFA) .
• Suitable vinylidene chloride copolymers include: the copolymer of
• vinylidene chloride, N-tert.-butylacrylamide, n-butyl acrylate, and N-vinyl pyrrolidone e.g.70:23:3:4
• the copolymer of vinylidene chloride, N-tert.- butylacrylamide, n-butyl acrylate, and itaconic acid e.g. 70:21 :5:2
• the copolymer of vinylidene chloride, N-tert.-butylacrylamide, and itaconic acid e.g. 88: 10:2
• the copolymer of vinylidene chloride, n-butylmaleimide, and itaconic acid e.g.
• the copolymer of vinyl chloride, vinylidene chloride, and methacrylic acid e.g. 65:30:5
• the copolymer of vinylidene chloride, vinyl chloride, and itaconic acid e.g. 70:26:4
• the copolymer of vinyl chloride, n-butyl acrylate, and itaconic acid e.g. 66:30:4
• the copolymer of vinylidene chloride, n-butyl acrylate, and itaconic acid e.g.
• the subbing layer has a dry thickness of no more than 2 ⁇ or preferably no more than 200 mg/m 2 .
• the security document precursor may include additional layers and/or foils.
• Such an additional layer can, for example, be an adhesive layer, a layer including UV stabilizers for protecting color images against bleaching or a layer containing an infrared antihalation dye for improving the sharpness of a colour laser marked image.
• An adhesive foil may be interlaminated in order to make falsification by delamination more difficult.
• an adhesive layer may be applied as a layer on top of e.g. a color laser markable layer.
• the use of an adhesive foil instead of an adhesive layer has the advantage is that an adhesive foil does not extract some of the more soluble ingredients in the laser markable layer like an adhesive layer can do upon coating and drying. Variation in the concentration of the soluble ingredients leads to inconsistencies in the color production during laser marking.
• Suitable adhesive foils include pressure-sensitive and thermo-sensitive adhesive foils.
• a range of so-called hot melt foils are well-known to one skilled in the art of security films and security documents.
• a preferred hot melt foil in the present invention is a polyurethane foil.
• Suitable commercially available hot melt foils include PlatilonTM ID5051 , a 35 ⁇ polyurethane foil available from Epurex.
• Other suitable hot melt foils are ScapaTM Thermofoil G160 and G161.
• PETG Another preferred adhesive foil is PETG. Contrary to biaxially oriented polyethylene terephthalate, a non-oriented PETG foil softens rapidly near the glass transition temperature and can thus also be used for adhesive purposes.
• the adhesive foil is made of a non-chlorinated polymer. Adhesive foils based on a chlorinated polymer may cause background discoloration. Preferred adhesive foils include polyester, polyester urethane, polyether urethane or polyolefin hot melt foils. [00152] If the adhesive is applied as an adhesive layer on a color laser markable layer or on polymeric support, this may be performed by methods such as solvent coating, casting, or hot melt extrusion.
• thermo adhesive compositions are disclosed in WO 2009/063058 (AGFA) .
• Preferred thermo adhesive layers are based on a hydroxyl- functional, partially-hydrolyzed vinyl chloride/vinyl acetate resin such as, for example, available under the trade name of UCAR(TM) VAGD Solution vinyl resin from Dow Chemical Company.
• the adhesive foil preferably has a thickness smaller than 65 ⁇ , more preferably smaller than 50 ⁇ and most preferably smaller than 40 ⁇ .
• the security document may include one or more additional security features to increase the difficulty for falsifying the document.
• Suitable other security features such as anti-copy patterns; guilloches; line patterns; endless text; miniprint; microprint; nanoprint; rainbow coloring; barcodes including 2D-barcodes; colored fibres; fluorescent fibres and planchettes; fluorescent pigments including fluorescent hi-lites; OVD (Optically Variable Device) and DOVID (Diffractive Optically Variable Image Device) such as holograms, 2D and 3D holograms, holograms with kinematic effects like KinegramsTM; overprint; relief embossing;
• a preferred embodiment of the present invention is an apparatus for producing a security document including a first device for producing a first part of a colour image by colour laser marking a security document precursor; and a second device for producing a second part of the colour image, wherein the second device includes no lasers.
• the first device for producing a first part of a colour image by colour laser marking preferably includes two infrared lasers, one infrared laser having an emission wavelength between 1000 nm and 1200 nm and the other infrared laser having an emission wavelength between 800 nm and 1000 nm.
• the second device for producing a second part of the colour image is a thermosublimation printer.
• the second device for producing a second part of the colour image is an inkjet printer, more preferably a UV curable inkjet printer.
• the first and second devices are integrated into the apparatus for
• the first and second devices are integrated in such a manner that a security document is first colour laser marked by the first device before being imaged by the second device.
• CCE is Bayhydrol H 2558, a anionic polyester urethane (37.3%) from
• Resorcinol from Sumitomo Chemicals. Par is a dimethyltrimethylolamine formaldehyde resin from Cytec industries.
• PAR-sol is a 40wt% aqueous solution of Par.
• PEA is TospearlTM 120 from Momentive Performance materials.
• PEA-sol is a 10wt% (50/50) aqueous/ethanol dispersion of PEA.
• DowfaxTM2A1 from Pilot Chemicals C is a Alkyldiphenyloxide disulfonate
• DOW-sol is a 2.5wt% solution of DowfaxTM 2A1 in isopropanol.
• SurfynolTM 420 from Air Products is a non ionic surfactant.
• Surfynsol is a 2.5wt% solution of SurfynolTM 420 in isopropanol.
• MEK is an abbreviation used for methylethylketone.
• SolvinTM 557RB is a vinylchloride-vinylacetate copolymer with 1 1 % vinyl acetate, provided by SOLVAY.
• SolvinSol is a 12.5 wt% solution of SolvinTM 557RB in MEK.
• HDP is the hydrogen donor-precursor CASRN 129104-70-7 prepared according to the synthesis given on page 31 of EP 605149 A (JUJO PAPER) for the compound (19).
• BLD is crystal violet lactone (CASRN 1552-42-7) available from YAMADA CHEMICAL CO.
• MLD is a bisindolylphthalide leuco dye (CASRN50292-95-0) available as
• IR-2sol is a 0.15 wt% solution in MEK of the infrared dye CASRN 223717-
• A (AGFA) .
• IR-3 was synthesized as follows via the intermediates IR-INT1 and
• the synthesis of the intermediate INT-B was performed as follows. 1 mol of 1 ,1 ,2-trimethyl-1 H-benzo[e]indole (CASRN41532-84-7) and 2 mol of n-butyl bromide were stirred in 0.5 I sulfolane for four hours at 100°C. INT- B was filtered, washed with ethyl acetate and dried. The yield was 61 %.
• IR-INT1 16 g; 22 mmol
• acetonitrile 200 mL
• potassium nonafluorobutanesulfonate CASRN29420-49-3 from TCI Europe N.V.; 8.1 g; 24 mmol
• this mixture was heated at 70 °C for 15 minutes.
• water 100 mL
• the precipitated IR-absorber was isolated by filtration, washed consecutively with a mixture of acetonitrile / water 2/1 (20 mL), methyl tert. butylether (MTBE) (20 mL) and dried in vacuo.
• the yield of IR-INT2 was 14 g (67%).
• the absorption maximum of IR-INT2 measured in methanol was 844 nm.
• benzenesulfinate (CASRN873-55-2 from Aldrich; 0.297 g; 1 ,81 mmol). After stirring for 2 hours the precipitated IR-absorber was isolated by filtration, washed with MTBE (5 mL) and dried in vacuo. The yield of IR-3 was 1.2 g (65%). The absorption maximum measured in methanol was 910 nm. The absorption maximum of IR-3 measured in CH2CI2 including 6.5 x 10 "6 wt% of methanesulfonic acid was 923 nm.
• IR-3sol is a 0.15 wt% solution in MEK of the infrared dye IR-3.
• CORE is a 500 ⁇ opaque PETG core available as PET-G 500 type 931 1 from WOLFEN.
• EXAMPLE 1 This example illustrates the production of a security document in accordance with the invention.
• the security document is produced in two steps by first colour laser marking a security document precursor and then in a second step applying a complementary colour on the polymeric overlay by thermosublimation.
• a coating composition SUB-1 was prepared by mixing the components according to Table 2 using a dissolves
• a 1 100 ⁇ thick polyethylene terephthalate sheet was first longitudinally stretched and then coated on both sides with the coating composition SUB-1 to a wet thickness of 10 ⁇ . After drying, the longitudinally stretched and coated polyethylene terephthalate sheet was transversally stretched to produce a double side subbed 63 ⁇ thick sheet PET1 , which was transparent and glossy.
• the coating compositions BCOL1 and MCOL1 were prepared in the same way by mixing the components according to Table 3 using a dissolver.
• the coating composition BCOL1 was coated with an Elcometer Bird Film Applicator (from ELCOMETER INSTRUMENTS) on one side of the PET-C support PET1 at a coating thickness of 100 ⁇ and subsequently dried for 2 minutes at 20°C on the film applicator and for a further 15 minutes in an oven at 75°C.
• an Elcometer Bird Film Applicator from ELCOMETER INSTRUMENTS
• the coating composition MCOL1 was coated with an Elcometer Bird Film Applicator (from ELCOMETER INSTRUMENTS) on the opposite side of the PET-C support PET1 coated with BCOL1 at a coating thickness of 100 ⁇ and subsequently dried for 2 minutes at 20°C on the film applicator and for a further 15 minutes in an oven at 75°C to deliver the colour laser markable security laminate ILL
• An assembly was made of, in order, a white opaque core support CORE, the colour laser markable security laminate IL1 and a polymeric overlay PET1 , wherein the side coated with BCOLI of the colour laser markable security laminate IL1 faces the white opaque core support CORE.
• the security document precursor SDP-1 was then first colour laser marked with a cyan and magenta part of a colour image by two infrared lasers of different emission wavelength , and then a yellow part of the colour image was printed in register with the cyan and magenta part of the colour image using thermosublimation printer.
• a first optically pumped semiconductor laser emitting at 920 nm (Genesis MX 920-4000 MTM from COHERENT) was used for producing a magenta coloured wedge of ten 1 cm x 1 cm square boxes of increasing optical density up to a maximum optical density of 1.29 in the colour laser markable layer coated from MCOL1.
• the laser was used at a power level of 4.9 W, a dither of 0.025, a scan speed of 100 mm/s and at a pulse repetition rate of 1.2 kHz.

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• 2012
  • 2012-11-12 EP EP12192155.5A patent/EP2730425B1/de not_active Not-in-force
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