PROCESS FOR PREPARING TAMPERPROOF SECURITY DOCUMENTS AND TAMPERPROOF SECURITY DOCUMENT

FIELD OF THE INVENTION

The invention relates to a method for preparing security documents secured against alteration and tempering.

BACKGROUND OF THE INVENTION

Value documents according to the present invention are bank notes, cheque forms, shares, certificates, postage stamps, air tickets, labels for product protection, identity documents, passports and the like. Bank notes are normally manufactured from so-called security papers consisting of cotton fibers and have special security features, such as a security thread at least partly incorporated into the paper, and a watermark. The period of circulation of a bank note depends on how much it is stressed. Certain denominations are preferably used in financial transactions and thus have a shorter period of circulation due to the greater wear and tear due to environmental influences. The main cause for a restricted period of circulation of bank notes is seen to be early soiling. Since bank note paper is very porous, it has a large surface area or high surface roughness. Even if the resulting projections and cavities are in orders of magnitude which cannot be resolved by the human eye, they offer ideal conditions for dirt deposits in comparison with a smooth surface.

WO 98/15418 discloses a security document, such as a banknote, comprising a single flexible sheet formed from a substrate bearing indicia, said sheet having a first portion of transparent plastics material, and a security device provided at a second position of the sheet spaced laterally from the transparent first portion, wherein the transparent first portion includes self-verification means to verify or inspect the security device when the sheet is bent, folded or twisted to bring the first and second portions into register with one another. However, in this case the usual and time-tested security elements such as portrait watermark and windowed security thread must be forgone, as well as the special properties such as sound and feel of bank note paper. Also, the steel gravure printing usual in the bank note sector, which serves as an additional tactile authenticity mark due to the relief arising from the inking, leads

only to a flat, hardly noticeable relief on plastic substrates. Moreover, pure plastic bank notes are very sensitive to heat, so that plastic substrates have a strong tendency to shrink particularly in countries with unfavorable climatic conditions. In particular with regard to falsification security, plastic bank notes have the decisive disadvantage that the substrate is readily available and can be procured by anyone.

WO 96/28610 discloses a method for producing security paper which includes a security feature, which method comprises forming paper in a wet state, which paper incorporates one or more security features, applying to the paper a sizing agent, thereafter applying to one or both sides of the sized paper a coating comprising an unpigmented polyurethane which may optionally comprise a functional additive provided that the presence of the functional additive does not increase the opacity of the paper by more than 1%, thereafter drying the paper, said coating composition being such as to provide a film, when cast on a glass surface, having a Konig hardness of from 15 to 130 seconds, and also passing the water resistance test as defined by the following steps: a) the total formulation to be used in the coating is cast on a glass plate so as to produce a film with a dry weight of 80g/m ² ; b) the film is initially dried at 23 ⁰ C. Once it is tack free it is dried for an additional hour at 80 'C; c) the film is weighed before being wetted and tested for tensile strength, Young's Modulus and is visually checked for any change in its transparency; d) a sample of the film is boiled in water containing 10g/L Na ₂ CO ₃ for 30 mins; e) the film is then rinsed in cold water and the steps b) to c) are then repeated; wherein when the film is dried and re-weighed the film meets the following criteria: i) the wet tensile strength and Young's Modulus of the boiled film is not less than 90% of the initial film wet tensile strength and Young's Modulus; ii) the film shows no perceptible loss of transparency, and iii) the dried weight of the film is not less than 98% of the original weight. This reduces the soiling problem, but cannot increase the mechanical stability of a substrate. Multilayer substrates comprising a film core coated on both sides with paper plies have also been proposed. The strength of this laminate is increased in comparison with a pure paper substrate, but the soiling problem with the exterior paper layers is not solved. So as not to excessively increase the total thickness of such bank notes, the paper plies must moreover be designed very thin, so that the usual security features such as security thread or watermark can no longer be optimally incorporated.

US 2007/0017647Al discloses a security paper for producing value documents, exemplified by bank notes, passports or identification documents, comprising a flat substrate provided at least partly with a dirt-repellent protective layer for extending the life time and fitness for circulation, wherein the protective layer comprises at least two lacquer layers, a first lower one of said lacquer layers being formed by a physically drying lacquer layer applied to the substrate which makes contact with the substrate therebelow and closes its pores, and a second upper one of said lacquer layers protecting the substrate from physical and chemical influences. US 2007/0017647A1 discloses that the first lower lacquer layer is preferably elastic, is preferably formed by a water-based dispersion lacquer layer, preferably comprises a polyurethane, and is preferably based on a water-based dispersion of aliphatic polyester polyurethanes or styrene-acrylic polyurethanes . One skilled in the art would understand the term "physically drying lacquer" not defined in US 2007/0017647A1 to mean a lacquer drying or hardening to form a tight film at room temperature or on slight heating by evaporation of solvent or suspension medium, the degree of polymerization and/or molar mass of the binders remaining unchanged during this process e.g. coalescence of binder particles.

Identification cards and documents, such as driving licenses, national or government identification cards, bank cards, credit cards, controlled access cards and smart cards, carry certain items of information which relate to the identity of the bearer. Examples of such information or variable data include name, address, date of birth, signature and photo of the bearer. The ID cards or documents may in addition carry invariant data, i.e., data common to a large number of cards, for example the name of an employer, the name of the issuing authority and the name of a country.

A typical national passport is personalized by ink-jet-printing a citizen' s biographical and biometric information onto the data page of a blank passport consisting of a back and front cover and pages of security paper with security printing. The ink-jet-ink is partly absorbed in the security paper and any attempt to remove the ink will also destroy the surface of the page. However the information can be overwritten. After printing a transparent (possibly optically variable) foil is laminated on top of the data page as a whole or locally over the top of the image of the citizen. The thinness of the foli and its binding to the biographical data makes forgery/alteration difficult. However, under certain

circumstances the laminate foil can be integrally removed making it possible to alter the biographic data.

Identity theft is considered by many governments as being the fastest growing crime. Consequently efforts to improve the security of security documents and in particular ID-documents are presently being made to prevent forgery and alteration.

Therefore, it is highly desirable to be able to manufacture security documents secured against alteration using a simple manufacturing method. However, the application of soiling resistant and/or protective outermost layers as liquid compositions to paper- based security documents is accompanied by staining of the paper- base due to penetration through the porous paper base (so-called strike-through) , which can be observed on the reverse side of the document as greasy areas corresponding to the area to which the composition is applied together with changes in the information being protected e.g. leaching of print and image comprising the information. There is therefore a need for a means of providing soiling resistant and/or protective outermost layers as liquid compositions in which an outermost layer is produced without such disadvantages.

ASPECTS OF THE INVENTION

It is an aspect of the present invention to provide a simple method for manufacturing a secure ID document without changes in the information content of the information being protected or staining of the paper-base.

It is a further aspect of the present invention to provide ID documents, which are difficult to falsify and are tamperproof against changes in the information content of the information being protected or staining of the paper-base.

Further objects of the invention will become apparent from the description hereinafter.

SUMMARY OF THE INVENTION

It has been surprisingly found that the application of particular aqueous primer compositions comprising at least one polymer selected from the group consisting of vinyl ester homopolymers, vinyl ester copolymers, hydrolyzed vinyl ester homopolymers and hydrolyzed vinyl ester copolymers to a paper-based security document drying to a transparent layer prior to the

application of a protective crosslinkable liquid composition to the paper-based security document crosslinking to a glossy transparent layer is able to delay strike-through of the protective crosslinkable liquid composition sufficiently long to enable a crosslinkable composition to be applied and crosslinked without significant penetration into the security paper and moreover that the resulting protective layers are solvent-resistant i.e. survived the crosscut adhesion test after 24 hours immersion in acetone. Improved tamper-proofing is thereby realized. Furthermore, the primer and crosslinkable compositions are totally transparent and the gloss of the image being protected is substantially unchanged or increased by the coating, although deeper in colour, as would be expected with a transparent coating. No significant dulling or matting of the image is observed with the primer composition of the present invention.

Aspects of the present invention have been realized by a process for preparing a tamperproof security document comprising in order the steps of a) providing a security document comprising security paper having at least one image on at least one outermost surface of the security paper; b) applying by printing, coating or other application process an aqueous primer composition on at least one of the outermost surfaces of the security paper over the at least one image thereby forming a primer coating on at least the at least one image; c) drying said primer coating; d) optionally curing said primer composition; e) applying by printing, coating or other application process a crosslinkable composition over said primer coating; and f) curing said printed or coated crosslinkable composition, wherein said primer composition comprises at least one polymer selected from the group consisting of vinyl ester homopolymers, vinyl ester copolymers, hydrolyzed vinyl ester homopolymers and hydrolyzed vinyl ester copolymers.

Aspects of the present invention have also been realized by a process for preparing a tamperproof security document comprising in order the steps of a) applying by printing, coating or other application process an aqueous primer composition on at least one of the outermost surfaces of a security paper to provide a primer print or primer layer; b) drying said primer print or primer layer; c) optionally curing said primer print or primer layer; d) providing at least one image over said dried and optionally cured primer print or primer layer; e) applying by printing, coating or other application process a crosslinkable composition over the at least one image; and f) curing said printed or coated crosslinkable composition, wherein

said primer composition comprises at least one polymer selected from the group consisting of vinyl ester homopolymers, vinyl ester copolymers, hydrolyzed vinyl ester homopolymers and hydrolyzed vinyl ester copolymers. Aspects of the present invention have also been realized by a print comprising a security paper carrying a printed image on at least one side thereof, wherein said at least one printed image is provided with a primer composition comprising at least one polymer selected from the group consisting of one polymer selected from the group consisting of vinyl ester homopolymers, vinyl ester copolymers, hydrolyzed vinyl ester homopolymers and hydrolyzed vinyl ester copolymers.

Aspects of the present invention have also been realized by the use of a primer composition comprising at least one polymer selected from the group consisting of vinyl ester homopolymers, vinyl ester copolymers, hydrolyzed vinyl ester homopolymers and hydrolyzed vinyl ester copolymers for preventing the penetration of crosslinkable composition into security papers.

Further advantages and embodiments of the present invention will become apparent from the following description.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

The term "abherent agent", as used in disclosing the present invention means a substance that prevents adhesion of a material, either to itself or to other materials.

The term "printing", as used in disclosing the present invention, means application by a conventional impact or non-impact printing process including but not restricted to ink-jet printing, intaglio printing, screen printing, flexographic printing, offset printing, stamp printing, gravure printing and xerographic printing.

The term "security document", as used in disclosing the present invention, means bank notes, cheque forms, shares, certificates, postage stamps, air tickets, labels for product protection, identity documents, passports and the like.

The term ^λ identity document", as used in disclosing the present invention, means a document bearing identifying data about the product or the individual whose name appears thereon. ID documents include credit cards, bank cards, phone cards, passports, driving licences, network access cards, employee badges, debit cards,

security cards, visas, immigration documentation, national ID cards, citizenship cards, social security cards, security badges, certificates, identification cards or documents, voter registration cards, police ID cards, border crossing cards, legal instruments, security clearance badges and cards, gun permits, gift certificates or cards, membership cards and badges. The terms "document," "card," "badge" and "documentation" are used interchangeably throughout this patent application. The term "security paper", as used m disclosing the present invention, means a paper used in a security document.

The term "image", as used in disclosing the present invention means any way of representing information, such as pictures, logos, photographs, barcodes and text. The image may also comprise some form of a "security pattern", such as small dots, thin lines, holograms, microprint and Moire inducing patterns which may be produced using fluorescent inks, phosphorescent inks, pearlescent inks or other optically variable inks, such as metameric inks.

The term "ink", as used m disclosing the present invention, means a liquid which can be printed using conventional printing techniques and is not confined to liquids containing at least one colorant .

The term "vinyl-monomer", as used in disclosing the present invention, means a substance comprising a single vinyl group capable of chain polymerization. The term "polyvmyl-monomer", as used m disclosing the present invention, means a substance comprising a more than one vinyl group capable of chain polymerization e.g. a divinyl-monomer with two vinyl groups, a trivinyl-monomer with three vinyl groups, a tetravmyl-monomer with four vinyl groups. The term "substantially non-printable abhesive surface", as used in disclosing the present invention, means a surface which does not lend itself to efficient deposition of an ink by a conventional printing technique and/or to deposits of ink with substantially no adhesion to the abhesive surface. The term "substantially non-lammatable abhesive surface", as used m disclosing the present invention, means a surface which does not lend itself to efficient lamination and/or to laminates with substantially no adhesion to the abhesive surface.

The term "porous pigment", as used m disclosing the present invention, means a pigment with detectable pores detectable using techniques such as porosimetry i.e. contains pores m an open (unfilled) state. These pores can be micropores defined by IUPAC as

pores sizes < 2 nm, mesopores defined by IUPAC as pore sizes of 2 to 50 nm or macropores defined by IUPAC as pore sizes greater than 50 nm. Porous pigments often have very high specific surface areas (BET) e.g. 100 to greater than 1500 m ² /g associated with particle sizes greater than 1 μm and have measurable pore volumes e.g. 1.2mL/g for SYLOID™ W300. Examples of porous pigments are silica gels such as SIPERNAT™ 570, SIPERNAT™ 700 and SIPERNAT™ 220 from Degussa and SYLOID™ W300 from W. R. Grace.

A "layer or foil exclusive of porous pigment", as used in disclosing the present invention, means a layer or foil which does not contain porous pigment particles i.e. porous particles containing pores m an open (unfilled) state and does not include a layer or foil containing porous pigment, whose pores have been filled e.g. with a curable liquid. The term "UV" as used m disclosing the present invention is an abbreviation for ultraviolet radiation.

The term "ultraviolet radiation" as used in disclosing the present invention means electromagnetic radiation m the wavelength range of 100 to 400 nm. The term "actinic radiation" as used m disclosing the present invention means electromagnetic radiation capable of initiating photochemical reactions.

The term "thermal initiator" as used in disclosing the present invention means an initiator which generates initiating species upon exposure to heat.

The term "functional group" as used m disclosing the present invention means an atom or group of atoms, acting as a unit, that has replaced a hydrogen atom m a hydrocarbon molecule and whose presence imparts characteristic properties to this molecule. The term "polyfunctional" means more than one functional group.

The term "dispersion", as used m disclosing the present invention, means an intimate mixture of at least two substances, one of which, called the dispersed solid phase or colloid, is uniformly distributed in a finely divided state through the second substance, called the dispersion medium.

The term "wt%" is used m disclosing the present invention as an abbreviation for % by weight.

The term "substituted" as used in disclosing this present invention means that one or more of the carbon atoms and/or that a hydrogen atom of one or more of carbon atoms m an aliphatic group, an aromatic group or an alicyclic hydrocarbon group, are replaced by an oxygen atom, a nitrogen atom, a halogen atom, a silicon atom, a

sulphur atom, a phosphorous atom, selenium atom or a tellurium atom. Such substituents include hydroxyl groups, ether groups, carboxylic acid groups, ester groups, amide groups and amine groups.

Process for preparing a tamperproof ID document

Aspects of the present invention have been realized by a process for preparing a tamperproof security document comprising in order the steps of a) providing a security document comprising security paper having at least one image on at least one outermost surface of the security paper; b) applying by printing, coating or other application process an aqueous primer composition on at least one of the outermost surfaces of the security paper over the at least one image thereby forming a primer coating on at least the at least one image; c) drying said primer coating; d) optionally curing said primer composition; e) applying by printing, coating or other application process a crosslinkable composition over said primer coating; and f) curing said printed or coated crosslinkable composition, wherein said primer composition comprises at least Aspects of the present invention have also been realized by a process for preparing a tamperproof security document comprising in order the steps of a) applying by printing, coating or other application process an aqueous primer composition on at least one of the outermost surfaces of a security paper to provide a primer print or primer layer; b) drying said primer print or primer layer; c) optionally curing said primer print or primer layer; d) providing at least one image over said dried and optionally cured primer print or primer layer; e) applying by printing, coating or other application process a crosslinkable composition over the at least one image; and f) curing said printed or coated crosslinkable composition, wherein said primer composition comprises at least one polymer selected from the group consisting of vinyl ester homopolymers, vinyl ester copolymers, hydrolyzed vinyl ester homopolymers and hydrolyzed vinyl ester copolymers. According to a first embodiment of the process, according to the present invention, the cured crosslinkable composition is an abhesive layer.

According to a second embodiment of the process, according to the present invention, the process comprises the further steps of g) applying by printing, coating or other application process an abhesive crosslinkable composition over the cured crosslinkable composition; and h) curing the abhesive crosslinkable composition,

which is preferably applied by a printing process and particularly preferably by an ink-jet printing process.

According to a third embodiment of the process, according to the present invention, the crosslinkable composition is printed or coated according to a second image, thereby increasing the problems for the potential forger. The second image may comprise some form of a "security pattern", such as small dots, thin lines, holograms, microprint and Moire inducing patterns which may be produced using fluorescent inks, phosphorescent inks, pearlescent inks or other optically variable inks, such as metameric inks.

According to a fourth embodiment of the process, according to the present invention, the crosslinkable composition is printed or coated according to a second image and an abhesive crosslinkable composition is printed or coated on the second image according to a third image, thereby increasing the problems for the potential forger still further.

The crosslinkable composition can be a dispersion or a solution with the dispersion medium or solvent being aqueous or non-aqueous and if non-aqueous it can be inert or react in the crosslinking process. If inert the dispersion medium or solvent will usually be evaporated.

According to a fifth embodiment of the process, according to the present invention, the image on at least one side of the security paper is applied by ink-jet printing. According to a sixth embodiment of the process, according to the present invention, the primer composition is printed using ink- jet printing.

According to a seventh embodiment of the process, according to the present invention, the primer composition is applied pattern- wise.

According to an eighth embodiment of the process, according to the present invention, the crosslinkable composition is printed using ink-jet printing.

According to a ninth embodiment of the process, according to the present invention, the crosslinkable composition is applied pattern-wise .

According to a tenth embodiment of the process, according to the present invention, the crosslinkable composition is cured by UV- radiation. According to an eleventh embodiment of the process, according to the present invention, the crosslinkable composition is an

abhesive crosslmkable composition, which is printed using ink-jet printing .

According to a twelfth embodiment of the process, according to the present invention, the crosslmkable composition is an abhesive crosslmkable composition, which is cured by UV-radiation.

According to a thirteenth embodiment of the process, according to the present invention, the process comprises the further steps of g) applying by printing, coating or other application process an abhesive crosslmkable composition over the cured crosslmkable composition; and h) UV-curmg the printed or coated abhesive crosslmkable composition.

According to a fourteenth embodiment of the process, according to the present invention, at least one of the primer compositions and the crosslmkable composition is printed using mk-jet printing or if an abrasive crosslmkable composition is also applied at least one of the primer compositions, the crosslmkable composition and the abrasive crosslmkable composition is printed using mk-]et printing. To be mk-jettable the compositions have to have a viscosity of less than 15 mPas at the jetting temperature. The image or parts of the image can be provided by any suitable imaging method or combination of imaging methods. Invariant data may be applied by any impact printing technique, such as offset printing, flexographic printing, gravure, screen-printing, mk-jet printing and xerographic printing. For variable data a non-impact printing technique is preferably used, mk-jet printing is the preferred choice since additional security features can be included in the mk-jet inks.

Security paper

The security paper used m different types of security document varies with document type. They are generally based on non-wood fibres such as abaca, cotton, flax, hemp or sisal, although synthetic paper is used for some identity documents, student cards and labels. Compositions used include:

Security paper is generally rag paper, always wood-free, watermarked and chemically impregnated. It is very reactive and strong. Security papers carry identification marks which help to prevent counterfeiting e.g. dyes and watermarks. Security paper is also specially treated to prevent erasure, alteration or duplication of any writing or printing on its surface.

ArjoWiggms Security S. A. S. produces different security papers for use in security documents:

JETGUARD™ is used for the pages of passports, visas and identity cards .

Polymer in primer composition

The primer composition used m the process, according to the present invention, comprises at least one polymer selected from the group consisting of vinyl ester homopolymers, vinyl ester copolymers, hydrolyzed vinyl ester homopolymers and hydrolyzed vinyl ester copolymers.

Suitable vinyl esters include vinyl acetate and vinyl versatic acid esters (or vinyl versatates) . Versatic acids are highly branched C9 - C\\ aliphatic carboxylic esters (Rompps Chemie- Lexikon, 7 ^e edition, p. 3803) . Commercially available vinyl versatates wich are particularly suited are following compounds:

- VeoVA 9 (trade mark of Shell Chemicals Co.) : neo-nonanonic acid, ethenyl ester ; CAS No. 54423-67-5 ; in formula (I) R3 is CH3 ; Rl and R2 taken together are C7H25 ; - VeoVa 10 (trade mark of Shell Chemicals Co.) : tert-decanoic acid, ethenyl ester ; other names: tert-decanoic acid, vinyl ester ; versatic 10 acid, ethenyl ester ; CAS No. 26544-09-2 ; in formula (I) R3 is CH3 ; Rl and R2 taken together are CgH]_7 ;

- VeoVa 11 (trade mark of Shell Chemicals Co.) : tert-undecanoic acid, ethenyl ester ; CAS No. 163633-66-7 ; in formula (I) R3 is CH3 ; Rl and R2 taken together are CgH^ ;

A commercially available monomer according to formula (III) is Craynor 152 (trade mark of Cray Valley) : reaction product of tert- decanoic acid, oxiranylmethyl ester (available as Cardura ElO, tradename of Shell Chemical = glycidyl ester of versatic 10 acid, CAS No. 71206-09-2) with acrylic acid. Craynor 152 can be prepared as shown in the scheme below:

Other suitable monomers (according to formula II) for incorporation in the (co)polymer, although less preferred are :

- VeoVa 5 (registered trade mark of Shell Chemicals Co.) : CAS No. 3377-92-2 ; in formula (I) Rl = R2 = R3 = CH ₃ ;

- vinyl propanoate ; CAS No. 105-38-4 ; in formula (I) Rl = H, R2 = H, R3 = CH ₃ ; - vinyl 2-ethylhexoate ; CAS No. 94-04-2 ; in formula (I) Rl = H, R2 = C ₂ H ₅ , R3 = n-C ₄ H ₉ ;

- 2-ethylhexyl-2-propenoate ; CAS No. 103-11-7 ; in formula (I) Rl = H, R2 = H, R3 = tert-C ₇ H ₁₅ .

According to a fifteenth embodiment of the process, according to the present invention, the primer composition is exclusive of a polyurethane .

According to a sixteenth embodiment of the process, according to the present invention, the primer composition is exclusive of an aliphatic polyester polyurethane or a styrene-acrylic polyurethane.

Suitable vinyl ester homopolymers :

PVAc = poly (vinyl acetate)

Suitable hydrolyzed vinyl ester homopolymers and vinyl ester copolymers include:

PVAc = poly (vinyl acetate) # contains silanol groups

** tert-decanoic acid, ethenyl ester

MOWIOL and POVAL are registered trade marks belonging to Kuraray

Surfactants

According to a seventeenth embodiment of the process, according to the present invention, the primer composition further comprises a surfactant, which may be nonionic or ionic.

According to an eighteenth embodiment of the process, according to the present invention, the crosslmkable composition further comprises a surfactant, which may be nonionic or ionic.

Suitable nonionic surfactants include:

Surfactant no. 01 = ZONYL® FSN, a 40% by weight solution of F (CF ₂ CF ₂ ) i_

₉ CH ₂ CH ₂ O(CH ₂ CH ₂ O) _x H m a 50% by weight solution of isopropanol m water where x = 0 to about 25, from DuPont;

Surfactant no. 02 = ZONYL® FSN 100: F (CF ₂ CF ₂ ) _{λ 9} CH ₂ CH ₂ O (CH ₂ CH ₂ O) _X H where x = 0 to about 25, from DuPont;

Surfactant no. 03 = ZONYL® FS300, a 40% by weight aqueous solution of a fluorinated surfactant, from DuPont;

Surfactant no. 04 = ZONYL® FSO, a 50% by weight solution of F(CF ₂ CF ₂ ) ₁

₇ CH ₂ CH ₂ O (CH ₂ CH ₂ O) _y H where y = 0 to ca . 15 m a 50% by wt. solution of ethylene glycol m water, from DuPont;

Surfactant no. 05 = ZONYL® FSO 100, a mixture of ethoxylated nonionic fluorosurfactant with the formula: F(CF ₂ CF ₂ ) _! - ₇ CH ₂ CH ₂ O (CH ₂ CH ₂ O) _y H where y = 0 to ca . 15, from DuPont;

Surfactant no. 06 = TEGOGLIDE® 410, a polysiloxane-polymer copolymer surfactant, from Goldschmidt;

Surfactant no. 07 = TEGOWET®, a polysiloxane-polyester copolymer surfactant, from Goldschmidt;

Surfactant no. 08 = FLUORAD® FC431: CF ₃ (CF ₂ ) ₇ SO ₂ (C ₂ H ₅ )N-CH ₂ CO-(OCH ₂ CH ₂ ) _n OH from 3M;

Surfactant no. 09 = FLUORAD® FC126, a mixture of the ammonium salts of perfluorocarboxylic acids, from 3M;

Surfactant no. 10 = Polyoxyethylene-10-lauryl ether

A particularly preferred non-ionic surfactant is ZONYL® FSO 100. Suitable anionic surfactants include:

Surfactant no. 11 = ZONYL® 7950, a fluorinated surfactant, from

DuPont ;

Surfactant no. 12 = ZONYL® FSA, 25% by weight solution of

F (CF ₂ CF ₂ ) ₁ - ₉ CH ₂ CH ₂ SCH ₂ CH ₂ COOLI m a 50% by weight solution of isopropanol m water, from DuPont;

Surfactant no. 13 = ZONYL® FSE, a 14% by weight solution of

[F (CF ₂ CF ₂ ) i_ ₇ CH ₂ CH ₂ O] _x P (O) (ONH ₄ ) _y where x = 1 or 2; y = 2 or 1; and x + y = 3 m a 70% by wt solution of ethylene glycol xn water, from DuPont;

Surfactant no. 14 = ZONYL® FSJ, a 40% by weight solution of a blend of

F (CF ₂ CF ₂ ) ₁ - ₇ CH ₂ CH ₂ O] _x P(O) (ONH ₄ ) _y where x = 1 or 2; y = 2 or 1; and x + y = 3 with a hydrocarbon surfactant m 25% by weight solution of isopropanol m water, from DuPont;

Surfactant no. 15 = ZONYL® FSP, a 35% by weight solution of

[F (CF ₂ CF _? ) _{1 7} CH ₂ CH ₂ O] _x P(O) (ONH ₄ ) _y where x = 1 or 2; y = 2 or 1 and x + y = 3 in 69.2% by weight solution of isopropanol m water, from DuPont;

Surfactant no. 16 = ZONYL® UR: [F (CF ₂ CF ₂ ) _{1 7} CH ₂ CH ₂ O] _% P (0) (OH) _y where x =

1 or 2; y = 2 or 1 and x + y = 3, from DuPont;

Surfactant no. 17 = ZONYL® TBS: a 33% by weight solution of F (CF ₂ CF ₂ ) ₃

₈ CH ₂ CH ₂ SO ₃ H m a 4 ₌ 5% by weight solution of acetic acid in water, from DuPont;

Surfactant no. 18 = Ammonium salt of perfluoro-octanoic acid;

Ionic fluorosurfactants

According to a nineteenth embodiment of the process, according to the present invention, the primer composition further comprises an ionic fluorosurfactant .

According to a twentieth embodiment of the process, according to the present invention, the ionic fluorinated surfactant comprises a perfluoπnated group, with a CF ₃ (CF ₂ J _n - group wherein n is at least 3 being preferred and a CF ₃ (CF ₂ J _n - group wherein n is at least 5 being particularly preferred.

According to a twenty-first embodiment of the process, according to the present invention, the ionic fluorinated surfactant is an anionic, a cationic or amphoteric fluorinated surfactant. According to a twenty-second embodiment of the process, according to the present invention, the ionic fluorinated surfactant is an anionic fluorosurfactant, with anionic fluorosurfactants with sulphonate, sulphate, phosphate or carboxylate groups being preferred.

Suitable anionic fluorinated surfactants include:

Suitable cationic fluorinated surfactants are:

Suitable amphoteric fluorinated surfactants are:

Crosslinkable composition

According to a twenty-third embodiment of the process, according to the present invention, the crosslinkable composition comprises at least one initiator, at least one vinyl-monomer and at least one polyvmyl-monomer .

According to a twenty-fourth embodiment of the process, according to the present invention, the crosslinkable composition further comprises at least one organic solvent.

According to a twenty-fifth embodiment of the process, according to the present invention, the at least one polyvinyl monomer is a divinyl monomer.

According to a twenty-sixth embodiment of the process, according to the present invention, the at least one vinyl-monomer is an acrylate or methacrylate . According to a twenty-seventh embodiment of the process, according to the present invention, the at least one polyvinyl- monomer is a poly-acrylate monomer or a poly-methacrylate monomer.

According to a twenty-eighth embodiment of the process, according to the present invention, the crosslinkable composition comprises a combination of monomers, oligomers and/or prepolymers. The monomers, oligomers and/or prepolymers may possess different degrees of functionality, and a mixture including combinations of mono-, di-, tri- and higher functionality monomers, oligomers and/or prepolymers may be used. The curable compound (s) used in the curable liquid for the method for preparing a tamperproof ID document according to the present invention can be any monomer and/or oligomer found in Polymer Handbook, Vol. 1 & 2, 4th edition. Edited by J. BRANDRUP, et al. Wiley-Interscience, 1999. Suitable examples of monomers include: acrylic acid, meth- acrylic acid, maleic acid (or their salts) , maleic anhydride; alkyl- (meth) acrylates (linear, branched and cycloalkyl) such as methyl- (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; aryl(meth)- acrylates such as benzyl (meth) acrylate and phenyl (meth) -acrylate; hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) -acrylate and hydroxypropyl (meth) acrylate; (meth) acrylates with other types of functionalities (e.g. oxirane, amino, polyethylene oxide, phosphate- substituted) such as glycidyl (meth) acrylate, dimethylaminoethyl- (meth) acrylate, methoxypolyethyleneglycol (meth) acrylate and tri- propyleneglycol (meth) acrylate phosphate; allyl derivatives such as allyl glycidyl ether; styrenics such as styrene, 4-methyl-styrene, 4-hydroxystyrene, and 4-acetoxystyrene; (meth) acrylonitrile; (meth)- acrylamides (including N-mono and N, N-disubstituted) such as N-benzyl (meth) acrylamide; maleimides such as N-phenyl maleimide, N-benzyl maleimide and N-ethyl maleimide; vinyl derivatives such as vinylcaprolactam, vinylpyrrolidone, vinylimidazole, vinylnaphthalene

and vinyl halides; vinylethers such as vinylmethyl ether; and vinylesters of carboxylic acids such as vinylacetate and vinylbutyrate .

Preferred monomers and oligomers are selected from 1,6-hexane- diol acrylate, alkoxylated aliphatic diacrylates, alkoxylated hexanediol diacrylate, alkoxylated neopentyl glycol diacrylate, di- ethylene glycol diacrylate, dipropyleneglycol diacrylate, ethoxy- lated(lθ) bisphenol A diacrylate, neopentyl glycol diacrylate, tri- ethylene glycol diacrylate, tripropylene glycol diacrylate, 2(2- ethoxyethoxy) ethyl acrylate, isobornyl methacrylate, isobornyl acrylate, isodecyl acrylate, lauryl acrylate, tetrahydrofurfuryl acrylate, tridecyl acrylate, tridecyl methacrylate, ditrimethylol- propane tetraacrylate, dipentaerythritol tetraacrylate, pentaeryth- ritol tetraacrylate, ethoxylated ( 15) trimethylolpropane triacrylate, dipentaerythritol triacrylate, trimethylol-propane triacrylate, trimethylolpropane trimethacrylate, aliphatic urethane acrylates, amine modified polyether acrylate oligomers, aromatic urethane acrylates, epoxy acrylates and polyester acrylate oligomers. Suitable crosslinkable compositions (CC) include:

Suitable vinyl-monomers (VM) include:

Suitable polyvinyl-monomers (PVM) include:

UV-photoinitiators for the crosslinkable composition

According to a twenty-ninth embodiment of the process, according to the present invention, comprises at least one UV- imtiator . According to a thirtieth embodiment of the process, according to the present invention, the crosslinkable composition comprises at least one UV-mitiator selected from the group consisting of: benzoin, benzoin ethers, benzil, benzil ketal derivatives, α- dialkoxyacetophenones, α-hydroxy-alkyl-phenones, α-amino-alkyl- phenones, acyl-phosphme oxides, benzophenone, benzophenone derivatives, xanthones, amines, benzanthrone (BZA), thioxanthone derivatives, thioxanthone, thiotitanoces amines and Michler' s Ketone derivatives 4 , 4' -bis (diethylammo) benzophenone (BEABP) . UV-photomitiators suitable for use in the primer, crosslinkable and abhesive crosslinkable compositions of the present invention have to be compatible with a water-containing hydrophilic environment and to have a UV-light absorption compatible with the UV-light source used. Moreover, UV-photomitiators suitable for use m the compositions of the present invention preferably do not evaporate, sublime, decompose or substantially lose their activity in other ways upon subjection to a short drying/heating step e.g. upon heating for 3 minutes at 130 ⁰ C.

According to a thirty-first embodiment of the process, according to the present invention, the at least one UV- photoinitiator used m at least one of the primer composition, the crosslinkable composition and the abhesive crosslinkable composition has a half-life of greater than 3 minutes when heated to 130°C.

Suitable UV-photomitiators include both low molecular weight compounds and oligomers, such as the ESACURE® range of photoinitiators produced by Lamberti Spa. Furthermore, suitable UV- photoinitiators also include cationic and free radical UV- photoimtiators .

UV-photomitiators suitable for use in the compositions of the present invention include:

Dispersion medium or solvent in crosslmkable composition

The dispersion medium or solvent in the crosslinkable composition may comprise monomers and/or oligomers and/or water and/or organic solvents, such as alcohols, fluorinated solvents and dipolar aprotic solvents. However, the curable liquids preferably do not comprise an evaporable component, but, sometimes, it can be advantageous to incorporate an extremely small amount of an organic solvent in such inks to improve adhesion to the surface of the ink-receiver after UV curing. In this case, the added solvent can be any amount in the range that does not cause problems of solvent resistance and VOC, and preferably 0.1-5.0 wt%, and particularly preferably 0.1-3.0 wt%, each based on the total weight of the curable liquid.

Suitable organic solvents include alcohol, aromatic hydrocarbons, ketones, esters, aliphatic hydrocarbons, higher fatty acids, carbitols, cellosolves, higher fatty acid esters. Suitable alcohols include, methanol, ethanol, propanol and 1-butanol, 1- pentanol, 2-butanol, t-butanol. Suitable aromatic hydrocarbons include toluene, and xylene. Suitable ketones include methyl ethyl ketone, methyl isobutyl ketone, 2, 4-pentanedione and hexafluoroacetone . Also glycol, glycolethers, N-methylpyrrolidone, N, N-dimethylacetamid, N, N-dimethylformamid may be used.

Fluorescent or phosphorescent compounds

According to a thirty-second embodiment of the process, according to the present invention, at least one of the primer composition, the crosslinkable composition and, if applicable, the abhesive crosslinkable composition further comprises at least one luminescent entity e.g. a bead, fibre, particle or dye comprises at least one fluorescent compound or at least one phosphorescent compound to introduce additional security features. Luminescent beads and fibres are usually too large to be jettable. Examples of suitable UV-fluorescent and phosphorescent compounds include Tinopal™ grades such as Tinopal™ SFD, Uvitex™ grades such as Uvitex™ NFW and UVITEX™ OB from CIBA-GEIGY SPECIALTY CHEMICALS; LUMILUX™ luminescent pigments from HONEYWELL; KEYFLUOR™ dyes and pigments from KEYSTONE; Leukophor™ grades from CLARIANT; Blancophor™ grades such as Blancophor™ REU and Blancophor™ BSU from BAYER; and fluorescent dyes from SYNTHEGEN. According to a thirty-third embodiment of the process, according to the present invention, at least one of the primer composition, the crosslinkable composition and, if applicable, the

abhesive crosslmkable composition further comprises at least one fluorescent compound in a concentration of 0.1 to 20 wt% based on the total weight of the composition applicable, with 1 to 10 wt% being preferred.

Biocides

According to a thirty-fourth embodiment of the process, according to the present invention, the crosslmkable composition further comprises at least one biocide.

Suitable biocides for the curable liquid used m the method for preparing a tamperproof ID document according to the present invention include sodium dehydroacetate, 2-phenoxyethanol, sodium benzoate, sodium pyridmethion-1-oxide, ethyl p-hydroxybenzoate and 1, 2-benzisothiazolin-3-one and salts thereof. A preferred biocide for the curable liquid is Proxel™ GXL available from ZENECA COLOURS.

A biocide is preferably added in an amount of 0.001 to 3 wt.%, more preferably 0.01 to 1.00 wt . %, each based on the curable liquid.

Abhesive crosslmkable composition

According to a thirty-fifth embodiment of the process, according to the present invention, the crosslmkable composition is abhesive or the crosslmkable composition is printed or coated with an abhesive crosslmkable composition, wherein the abhesive crosslmkable composition further comprises at least one initiator, at least one vinyl-monomer, at least one polyvmyl-monomer and at least one abherent agent.

Suitable abhesive crosslmkable compositions include "SCOTCHGARD®" Phototool Protector from 3M, which is a solvent-free, low-viscosity solution with the following composition:

3- (tπmethoxysilyl) propyl glycidyl ether is the polymeπzable

abherent agent. This solution is ink-jettable, has a viscosity at 25°C of 11.4 mPa.s and a surface tension of 23.6 mN/m.

Abherent agents

The abherent agent used in the abhesive crosslinkable composition used in the process, according to the present invention, causes the outermost layer to have a difficult-to-wet surface. This surface preferably has a surface energy of less than 28 mJ/m ² . The abherent agent must be present in the cured outermost layer produced with the abhesive crosslinkable composition in a polymeric form otherwise it can be easily removed by wiping and using a strong organic solvent such as toluene or a chlorinated solvent. Low molecular weight fluorosurfactants are not suitable abherent agents in the present invention.

A single abherent agent or a mixture of abherent agents may be used as long as the abhesive properties of the outermost layer are obtained.

The abherent agent may be present in the abhesive crosslinkable composition as a polymerizable compound or as a polymeric abherent agent or a combination of both. Preferably the abherent agent is a silicone-modified or a fluorinated polymerizable compound. The abherent agent is preferably exclusive of epoxysilanes modified with oxyalkylene ether groups. According to a thirty-sixth embodiment of the process, according to the present invention, the crosslinkable composition is abhesive or the crosslinkable composition is printed or coated with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises at least one abherent agent selected from the group consisting of fluorinated (meth) acrylates and fluorinated ethylenes.

According to a thirty-seventh embodiment of the process, according to the present invention, the crosslinkable composition is abhesive or the crosslinkable composition is printed or coated with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises at least one polymeric abherent agent selected from the group consisting of a polytetrafluoroethylene, copolymers of fluorinated ethylene, polymers of fluorinated (meth) acrylates, copolymers of fluorinated (meth) acrylates, perfluoro (alkyl vinyl ether) s and polyvinylidene fluoride .

According to a thirty-eighth embodiment of the process, according to the present invention, the crosslinkable composition is abhesive or the crosslinkable composition is printed or coated with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises at least one polymeric abherent agent selected from the group consisting of polymers of fluorinated (meth) acrylates and copolymers of fluorinated (meth) acrylates, wherein the fluorinated (meth) acrylate is selected from the group consisting of 2, 2 , 2-trifluoroethyl-α-fluoroacrylate (TFEFA), 2,2,2-trifluoroethyl-methacrylate (TFEMA), 2,2,3,3- tetrafluoropropyl-α-fluoroacrylate (TFPFA) , 2,2, 3, 3-tetrafluoro- propyl-methacrylate (TFPMA), 2, 2 , 3, 3, 3-pentafluoropropyl-α- fluoroacrylate (PFPFA) , 2,2,3,3, 3-pentafluoro-propyl -methacrylate (PFPMA), IH, lH-perfluoro-n-octyl acrylate, IH, lH-perfluoro-n-decyl acrylate, IH, lH-perfluoro-n-octyl methacrylate, IH, lH-perfluoro-n- decyl methacrylate, IH, IH, 6H, 6H-perfluoro-1, 6-hexanediol diacrylate, IH, IH, 6H, 6H-perfluoro-1, 6-hexanediol dimethacrylate, 2- (N-butylper- fluorooctane-sulfonamido) -ethyl acrylate, 2- (N-ethyl perfluoro- octanesulfonamido) ethyl acrylate, 2- (N-ethyl perfluoro-octane- sulfonamido) ethyl methacrylate, C ₈ F ₁₇ CH ₂ CH ₂ OCH ₂ CH ₂ -OOC-CH=CH ₂ and C ₈ F _I7 CH ₂ CH ₂ OCH ₂ CH ₂ -OOC-C (CH ₃ ) =CH ₂ .

According to a thirty-ninth of the process, according to the present invention, the crosslinkable composition is abhesive or the crosslinkable composition is printed or coated with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises an abherent agent selected from the group consisting of silicone-modified (meth) acrylates and epoxy- functional silane compounds, the epoxy-functional silane compound being preferably selected from the group consisting of γ-glycidoxy- propyl trimethoxysilane, γ-glycidoxypropyl triethoxysilane, β- glycidoxyethyl trimethoxysilane, γ- (3, 4-epoxy-cyclohexyl) propyl trimethoxysilane and β- ( 3, 4-epoxycyclohexyl) ethyl trimethoxysilane.

According to a fortieth embodiment of the process, according to the present invention, the crosslinkable composition is abhesive or the crosslinkable composition is printed or coated with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises a polymeric abherent agent selected from the group consisting of polymers of dimethylsiloxane acrylate, copolymers of dimethylsiloxane acrylate, dimethyl siloxane modified polyethers, polymers of silicone-modified (meth) acrylates, copolymers of silicone-modified (meth) acrylates, dimethyl siloxane modified polyesters, silicone glycol copolymers, polymers of epoxy-

functional silane compounds and copolymers of epoxy-functional silane compounds, the epoxy-functional silane compound being selected from the group consisting of γ-glycidoxy-propyl trimethoxysilane, γ-glycidoxypropyl triethoxysilane, β-glycidoxyethyl trimethoxysilane, γ- (3, 4-epoxycyclohexyl) propyl trimethoxysilane and β- ( 3, 4-epoxycyclohexyl) ethyl trimethoxysilane .

Abherent agents suitable as polymerizable compound constitute preferably from 20 to 99.6%, more preferably 24 to 90%, and most preferably 30 to 80% by weight of the total composition of the abhesive crosslinkable composition.

Abherent agents suitable as a polymerizable compound include silicone-modified (meth) acrylates, fluorinated (meth) acrylates, fluorinated ethylenes and epoxy-functional silane compounds.

Preferred silicone-modified acrylates include Ebecryl™ 350 (silicon diacrylate) and Ebecryl™ 1360 (silicon hexaacrylate) from UCB, Belgium; Actilane™ 800 (silicon acrylate) from AKZO-NOBEL NV; and CN990™ (siliconized urethane acrylate oligomer) from SARTOMER. Illustrative examples of suitable epoxy-silanes include γ-glycidoxypropyl trimethoxysilane, γ-glycidoxypropyl triethoxysilane, β- glycidoxyethyl trimethoxysilane, (- (3, 4-epoxycyclohexyl ) propyl trimethoxysilane, β- (3, 4-epoxycyclohexyl ) ethyl trimethoxysilane, and the like. The most preferred epoxy-silane compound is γ-glycidoxypropyl trimethoxysilane.

Examples of suitable epoxy-silanes include (metha) acryl- oxyalkylalkoxysilanes such as (- (meth) acryloxypropyltrimethoxy- silane, (- (meth) acryloxypropyltriethoxysilane and (- (meth) acryloxy- propyl-triisopropoxysilane; (meth) acryloxyalkylalkoxyalkyl si lanes such as (- (meth) acryloxypropylmethyldimethoxysilane and (-(meth)- acryl-oxypropylmethyldiethoxysilane; vinyltrimethoxysilane, vinyltri-ethoxysilane, vinyltriisopropoxysilane, aryltriethoxy- silane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane and vinyltris (2-methoxyethoxy) silane .

The abherent agent present in the cured layer produced with the abhesive crosslinkable composition may be selected from the group consisting of polymers of dimethylsiloxane; copolymers of dimethylsiloxane; dimethyl siloxane-modified polyethers; dimethyl siloxane modified polyesters; silicone glycol copolymers; polymers of fluorinated ethylene such as polytetra-fluoroethylene, polyvinylfluoride and polyvinylidene fluoride (PVDF); copolymers of fluorinated ethylene such as a fluorinated ethylene/propylene copolymers and ethylene/tetrafluoroethylene copolymers; polymers of

fluorinated (meth) acrylates; copolymers of fluorinated (meth) acrylates; and perfluoro (alkyl vinyl ether) s.

Curing means

According to a forty-first embodiment of the process, according to the present invention, at least one of the crosslinkable composition and if applicable the abhesive crosslinkable composition is cured by exposure to actinic radiation, by thermal curing and/or by electron beam curing. A preferred means of radiation curing is ultraviolet radiation. Preferably the curing is performed by an overall exposure to actinic radiation, by overall thermal curing and/or by overall electron beam curing.

The curing means may be arranged in combination with the print head of the ink-jet printer, travelling therewith so that the curable liquid is exposed to curing radiation very shortly after being jetted.

In such an arrangement it can be difficult to provide a sufficiently small radiation source connected to and travelling with the print head. Therefore, a static fixed radiation source may be employed, e.g. a source of curing UV radiation, connected to the radiation source by means of flexible radiation conductive means such as a fibre optic bundle or an internally reflective flexible tube . Alternatively, the actinic radiation may be supplied from a fixed source to the radiation head by an arrangement of mirrors including a mirror upon the radiation head.

The source of radiation arranged not to move with the print head, may also be an elongated radiation source extending transversely across the ink-receiver surface to be cured and adjacent the transverse path of the print head so that the subsequent rows of images formed by the print head are passed, stepwise or continually, beneath that radiation source.

Any ultraviolet light source may be employed as a radiation source, such as, a high or low pressure mercury lamp, a cold cathode tube, a black light, an ultraviolet LED, an ultraviolet laser, and a flash light, if part of the emitted light can be absorbed by the photo-initiator or photo-initiator system. The preferred source is one exhibiting a relatively long wavelength UV-contribution having a dominant wavelength of 300-400 nm. Specifically, a UV-A light source is preferred due to the reduced light scattering therewith resulting in more efficient interior curing.

UV radiation is generally classed as UV-A, UV-B, and UV-C as follows :

• UV-A: 400 nm to 320 nm

• UV-B: 320 nm to 290 nm • UV-C: 290 nm to 100 nm.

According to a forty-fifth embodiment of the process, according to the present invention, at least one of the printed or coated primer composition, crosslinkable composition and, if applicable, abhesive crosslinkable composition is cured consecutively or simultaneously using two light sources of different wavelengths or illuminance. For example, the first UV source can be selected to be rich in UV-C, in particular in the range of 260 nm-200 nm. The second UV source can then be rich in UV-A, e.g. a gallium-doped lamp, or a different lamp high in both UV-A and UV-B. The use of two UV sources has been found to be advantageous e.g. a fast curing speed.

For facilitating curing, the ink-jet printer often includes one or more oxygen depletion units. The oxygen depletion units place a blanket of nitrogen or other relatively inert gas (e.g. CO ₂ ), with adjustable position and adjustable inert gas concentration, in order to reduce the oxygen concentration in the curing environment. Residual oxygen levels are usually maintained as low as 200 ppm, but are generally in the range of 200 ppm to 1200 ppm.

Thermal curing can be performed image-wise by use of a thermal head, a heat stylus, hot stamping, a laser beam, etc. If a laser beam is used, then preferably an infrared laser is used in combination with an infrared absorbing substance in the curable liquid .

Printing means

According to a forty-second embodiment of the process, according to the present invention, at least one of the primer composition, the crosslinkable composition and if applicable the abhesive crosslinkable composition is printed by a conventional printing process including but not restricted to ink-jet printing, intaglio printing, screen printing, flexographic printing, offset printing, stamp printing and gravure printing. In the case of ink- jet printing the curable liquid is jetted by one or more printing heads ejecting small droplets of liquid in a controlled manner through nozzles onto an ink-receiver surface, which is moving relative to the printing head(s) .

A preferred printing head for the ink-jet printing system according to the present invention is a piezoelectric head. Piezoelectric ink-jet printing is based on the movement of a piezoelectric ceramic transducer when a voltage is applied thereto. The application of a voltage changes the shape of the piezoelectric ceramic transducer in the printing head creating a void, which is then filled with ink. When the voltage is again removed, the ceramic expands to its original shape, ejecting a drop of ink from the print head. However the method for preparing a tamperproof ID document according to the present invention is not restricted to piezoelectric ink-jet printing. Other ink-jet printing heads can be used and include various types, such as a continuous type and thermal, electrostatic and acoustic drop on demand type.

At high printing speeds, the liquid must be ejected readily from the printing heads, which puts a number of constraints on the physical properties of the ink, e.g. a low viscosity at the jetting temperature, which may vary from 25°C to HO ⁰ C, a surface energy such that the printing head nozzle can form the necessary small droplets, a homogenous liquid capable of rapid conversion to a dry printed area.

The viscosity of the curable liquid used in the ink-jet printing method according to the present invention is preferably lower than 30 mPa.s, more preferably lower than 15 mPa.s, and most preferably between 2 and 10 mPas at a shear rate of 100 s ^"1 and a jetting temperature between 10 and 55°C.

The ink-jet printing head normally scans back and forth in a transversal direction across the moving ink-receiver surface. Often the ink-jet print head does not print on the way back. Bidirectional printing is preferred for obtaining a high areal throughput. Particularly preferred, is printing in a "single pass printing process", which can be performed by using page wide ink-jet printing heads or multiple staggered ink-jet printing heads which cover the entire width of the ink-receiver surface. In a single pass printing process the ink-jet printing heads usually remain stationary and the ink-receiver surface is transported under the ink-jet printing heads.

Print

Aspects of the present invention are realized by a print comprising a security paper carrying a printed image on at least one side thereof, wherein said at least one printed image is provided

with a primer composition comprising at least one polymer selected from the group consisting of one polymer selected from the group consisting of vinyl ester homopolymers, vinyl ester copolymers, hydrolyzed vinyl ester homopolymers and hydrolyzed vinyl ester copolymers .

According to a first embodiment of the print, according to the present invention, the primer composition is provided with a coating of a crosslinkable composition.

According to a second embodiment of the print, according to the present invention, the crosslinkable composition is cured.

According to a third embodiment of the print, according to the present invention, the crosslinkable composition is abhesive.

According to a fourth embodiment of the print, according to the present invention, the primer composition is provided with a coating of a crosslinkable composition, which is itself provided with an abhesive crosslinkable composition.

According to a fifth embodiment of the print, according to the present invention, the primer composition is provided with a coating of a crosslinkable composition, which is itself provided with a cured abhesive crosslinkable composition.

According to a sixth embodiment of the print, according to the present invention, the primer composition is provided with a coating of an abhesive crosslinkable composition or is provided with a coating of a crosslinkable composition, which is itself provided with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises at least one abherent agent selected from the group consisting of fluorinated (meth) acrylates and fluorinated ethylenes.

According to a seventh embodiment of the print, according to the present invention, the primer composition is provided with a coating of an abhesive crosslinkable composition or is provided with a coating of a crosslinkable composition, which is itself provided with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises at least one polymeric abherent agent selected from the group consisting of a polytetra- fluoro-ethylene, copolymers of fluorinated ethylene, polymers of fluorinated (meth) acrylates, copolymers of fluorinated (meth)- acrylates, perfluoro (alkyl vinyl ether) s and polyvinylidene fluoride, the fluorinated (meth) acrylate being preferably selected from the group consisting of 2, 2 , 2-trifluoroethyl-α-fluoroacrylate (TFEFA), 2,2,2-trifluoroethyl-methacrylate (TFEMA), 2,2,3,3- tetrafluoropropyl-α-fluoroacrylate (TFPFA) , 2,2,3, 3-tetrafluoro-

propyl-methacrylate (TFPMA), 2, 2, 3, 3, 3-pentafluoropropyl-α- fluoroacrylate (PFPFA) , 2,2,3,3, 3-pentafluoropropyl-methacrylate (PFPMA), IH, lH-perfluoro-n-octyl acrylate, IH, lH-perfluoro-n-decyl acrylate, IH, lH-perfluoro-n-octyl methacrylate, IH, lH-perfluoro-n- decyl methacrylate, IH, IH, 6H, 6H-perfluoro-1, 6-hexanediol diacrylate, IH, IH, 6H, 6H-perfluoro-1 , 6-hexanediol dimethacrylate, 2- (N-butylper- fluorooctanesulfonamido) ethyl acrylate, 2- (N-ethyl perfluoro- octanesulfonamido) ethyl acrylate, 2- (N-ethyl perfluorooctanesulfonamido) ethyl methacrylate, C ₈ F ₁₇ CH ₂ CH ₂ OCH ₂ CH ₂ -OOC-CH=CH ₂ and C ₈ F ₁₇ CH ₂ CH ₂ OCH ₂ CH ₂ -OOC-C (CH ₃ ) =CH ₂ .

According to an eighth embodiment of the print, according to the present invention, the primer composition is provided with a coating of an abhesive crosslinkable composition or is provided with a coating of a crosslinkable composition, which is itself provided with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises an abherent agent selected from the group consisting of silicone-modified (meth) acrylates and epoxy-functional silane compounds, the epoxy- functional silane compound being preferably selected from the group consisting of γ-glycidoxypropyl trimethoxysilane, γ-glycidoxypropyl triethoxysilane, β-glycidoxyethyl trimethoxysilane, γ- (3, 4-epoxy- cyclohexyl) propyl trimethoxysilane and β- (3, 4-epoxycyclohexyl) ethyl trimethoxysilane .

According to a ninth embodiment of the print, according to the present invention, the primer composition is provided with a coating of an abhesive crosslinkable composition or is provided with a coating of a crosslinkable composition, which is itself provided with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises a polymeric abherent agent selected from the group consisting of polymers of dimethyl- siloxane acrylate, copolymers of dimethylsiloxane acrylate, dimethyl siloxane modified polyethers, polymers of silicone-modified (meth) acrylates, copolymers of silicone-modified (meth) acrylates, dimethyl siloxane modified polyesters, silicone glycol copolymers, polymers of epoxy-functional silane compounds and copolymers of epoxy-functional silane compounds, the epoxy-functional silane compound being preferably selected from the group consisting of γ- glycidoxypropyl trimethoxysilane, γ-glycidoxypropyl triethoxysilane, β-glycidoxyethyl trimethoxysilane, γ- (3, 4-epoxycyclohexyl) propyl trimethoxysilane and β- (3, 4-epoxycyclohexyl) ethyl trimethoxysilane.

According to a tenth embodiment of the print, according to the present invention, the primer composition further comprises at least one luminescent entity.

According to an eleventh embodiment of the print, according to the present invention, the primer composition is provided with a coating of a crosslinkable composition, which further comprises at least one luminescent entity.

According to a twelfth embodiment of the print, according to the present invention, the primer composition is provided with a coating of an abhesive crosslinkable composition or is provided with a coating of a crosslinkable composition, which is itself provided with an abhesive crosslinkable composition, wherein the abhesive crosslinkable composition further comprises at least one luminescent entity.

Applications

The security documents with improved tamper-proofing realized with the process, according to the present invention, can be used for a wide variety of security applications including, but not limited to, bank notes, cheque forms, shares, certificates, postage stamps, air tickets, labels for product protection and identity documents .

The invention is illustrated hereinafter by way of COMPARATIVE EXAMPLES and INVENTION EXAMPLES without however being limited thereto. The percentages and ratios given in these examples are by weight unless otherwise indicated.

Papers used m the EXAMPLES:

The following materials not disclosed above were used:

• Perenol™ S Konz., a solventless polysiloxane block copolymer surfactant from COGNIS.

Photocurable compositions:

PCC 01 (jettable with a Xaar UPH ink-jet printing head) :

SCOTCHGARD from 3M (sprayable and jettable with a Xaar UPH mk-jet printing head) with the composition:

Primer compositions used:

Measurement methods used:

1. Adhesion:

The adhesion of a layer to the other layer or to the support was tested by using the cross-cut test pressing a 5 cm piece of Scotch Magic™ Tape 810 from 3M onto the sample and pulling it off with moderate force according to ASTM D3359-97 Test Method B. The test result was evaluated as:

A good adhesion of all layers to the security paper is required.

2. Solvent resistance:

Solvent resistance was evaluated by immersing the coated security paper m acetone for 24 hours at room temperature and then evaluating the adhesion as described above. The test result was evaluated as:

EXAMPLES 1 to 21

In EXAMPLES 1 to 21 compositions containing different polyvinyl esters and vinyl ester-copolymers, Polymer nr. 01 to 04, optionally with 2 wtl of the ionic fluorosurfactant AFS35 were evaluated. Paper 1 was coated with primer compositions given m Table 1 to the wet thickness given in Table 1 and the layers dried in a drying cupboard for 1 minute at 60 ⁰ C. The primer composition coating was then overcoated with a doctor blade with the abhesive crosslmkable composition "SCOTCHGARD®" or PCC 1 to the liquid thickness given m Table 1 and then immediately UV-cured m a DRSE-120 conveyor from Fusion UV Systems Ltd with a VPS/1600 UV lamp (speed 20 m/mm, 50% UV power setting giving over a width of 20 cm and a length m the transport direction of 0.8 cm: a UV-A intensity of 4.310 W/cm ² , a UVB intensity of 1.071 W/cm ² and a UVC intensity of 0.120 W/cm ² ) . The UV-curmg process was completed m less than 1 second.

Table 1 :

PVAc = poly (vinyl acetate) VAc = vinyl acetate

The adhesion and solvent resistance of the thereby realized abhesive protective layers were determined as described above and the results given in Table 2.

Table 2:

VAc = vinyl acetate

* mk-jettable with a Xaar UPH mk-jet printing head

At a sufficiently high concentration polyvinyl esters such as poly (vinyl acetate) and vinyl ester copolymers such as copolymers of ethylene, vinyl acetate and vinyl versatate provide primer layers, which prevent penetration of a crosslmkable composition such as "SCOTCHGARD®" . Primer compositions with aqueous dispersion of vinyl esters provide for penetration prevention at lower polyvinyl ester concentrations . Moreover, after coating with and crosslmkmg the crosslmkable composition, the resulting coating configuration exhibits excellent adhesion and solvent resistance on security paper.

Addition of the ionic fluorosurfactant AFS35 to the primer composition either brought about no improvement or in the case of Polymer nr . 04 reduced the solvent resistance observed. EXAMPLES 22 to 37

In EXAMPLES 22 to 37 compositions containing different hydrolyzed polyvinyl esters and vinyl ester-copolymers , Polymer nr. 06, 19, 35, 40, 43 and 47, optionally with 2 wt% of the ionic fluorosurfactant AFS35 were evaluated. Paper 1 was coated with primer compositions given in Table 3 to a wet thickness of 10 μm and the layers dried in a drying cupboard for 1 minute at 60 ⁰ C. The primer composition coating was then overcoated with a doctor blade with the abhesive crosslmkable composition "SCOTCHGARD®" or PCC 1 to a liquid thickness of lOμm and then immediately UV-cured in a

DRSE-120 conveyor from Fusion UV Systems Ltd with a VPS/1600 UV lamp (speed 20 m/min, 50% UV power setting giving over a width of 20 cm and a length m the transport direction of 0.8 cm: a UV-A intensity of 4.310 W/cm ² , a UVB intensity of 1.071 W/cm ² and a UVC intensity of 0.120 W/cm ² ) . The UV-cuπng process was completed in less than 1 second.

Table 3:

PVAc = poly (vinyl acetate)

The adhesion and solvent resistance of the thereby realized abhesive protective layers were determined as described above and the results given in Table 4.

Table 4:

PVAc = poly (vinyl acetate)

* mk-jettable with a Xaar UPH ink-jet printing head

At a sufficiently high concentration of hydrolyzed polyvinyl esters such as poly (vinyl acetate) and vinyl ester copolymers with hydrolyzable silane group provide primer layers, which prevent penetration of a crosslinkable composition such as "SCOTCHGARD®" . Moreover, after coating with and crosslmkmg the crosslinkable composition, the resulting coating configuration exhibits excellent adhesion and solvent resistance on security paper. Addition of the ionic fluorosurfactant AFS35 to the primer composition either brought about no improvement or in the case of polymer nr. 04 reduced the solvent resistance observed.

However, in the case of hydrolyzed vinyl ester copolymers with ethylene at a concentration of 10 wt% the ionic fluorosurfactant appears to be necessary to prevent penetration of a crosslinkable composition such as "SCOTCHGARD®" although the adhesion of the resulting layer configuration to the security paper is then unsatisfactory. An increase m the concentration of Polymer nr 43 together with a reduction in the surfactant concentration will result m satisfactory adhesion.

Having described in detail preferred embodiments of the current invention, it will now be apparent to those skilled in the art that numerous modifications can be made therein without departing from the scope of the invention as defined in the following claims. All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention .

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations of those preferred embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.