Method of providing a security document with a security feature, and security document

Abstract

A security document (1) comprises a paper document substrate (11) and a security element (2) embedded in said document substrate (11). The security element comprises an element substrate (21) and a material (22) sensitive to laser light. The method comprises the step of directing laser light (41) onto the document substrate (11) so as to alter said material (22), so as to provide said security element (2) with a detectable marking (3).

Claims

1. Method of providing a security document with a security feature, said security document comprising a document substrate, said document substrate being a paper substrate, said security document further comprising a security element embedded within said document substrate, said security element comprising an element substrate, said security element further comprising a material sensitive to laser light, wherein the method further includes the step of directing laser light onto the document substrate so as to alter said material embedded inside the document substrate, such that laser light is directed onto said document substrate where said security element is embedded so as to provide said security element with a detectable marking; and wherein the step of directing laser light onto the document substrate further includes passing laser light through the document substrate where the document substrate covers the security element such that the detectable marking is disposed where the security element is embedded within the document substrate.

2. Method according to claim 1, wherein the step of directing laser light onto the document substrate is carried out so as to substantially remove at least part of said material, so as to provide said security element with said detectable marking.

3. Method according to claim 2, wherein the step of directing laser light onto the document substrate is carried out so as to substantially sublimate at least part of said material, so as to provide said security element with said detectable marking.

4. Method according to claim 2, wherein said material is a conductive material and/or a metallic material.

5. Method according to claim 4, wherein said material is in the form of metallic particles.

6. Method according to claim 1, wherein said material sensitive to laser light is present as a layer on the security element.

7. Method according to claim 1, further including the step of producing perforations in the material after incorporation of said material onto or into said element substrate but prior to embedding the security element in the document substrate.

8. Method according to claim 7, wherein the step of producing perforations in the material further includes producing perforations in the element substrate.

9. Method according to claim 1, wherein the security element is a strip or a patch.

10. Method according to claim 1, wherein the security element comprises a cellulose substrate.

11. Method according to claim 1, wherein said detectable marking is visible by transmission but not by reflection, and/or wherein said detectable security marking is detectable using magnetic detectors.

12. Method according to claim 1, wherein said detectable marking is made in register with a feature of the document substrate.

13. Method according to claim 12, wherein said detectable marking is made in register with a mark printed on the document substrate or a watermark within the document substrate.

14. Method according to claim 12, wherein said detectable marking is made in register with a mark printed on the document substrate or a watermark within the document substrate, and in register with a side of the document substrate.

15. Method according to claim 12, wherein said detectable marking is made in register with a side of the document substrate.

16. Method according to claim 1, wherein said detectable marking is used to customize the security document.

17. Method according to claim 16, wherein said detectable marking is selected to identify an owner of the security document.

18. Method according to claim 1, wherein the step of directing laser light onto the document substrate so as to alter said material sensitive to laser light so as to provide said security element with a detectable marking, is carried out without substantially affecting the document substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) To complete the description and in order to provide for a better understanding of the disclosure, a set of drawings is provided. Said drawings form an integral part of the description and illustrate some embodiments of the disclosure, which should not be interpreted as restricting the scope of the disclosure, but just as examples of how the disclosure can be carried out. The drawings comprise the following figures:

(2) FIGS. 1A and 1B are schematic perspective views illustrating document substrates containing element substrates, in accordance with two embodiments of the disclosure.

(3) FIG. 2 schematically illustrate the insertion of cellulose strips into a paper, during the paper manufacturing stage, in accordance with a possible embodiment of the disclosure.

(4) FIGS. 3A and 3B are schematic perspective views illustrating a process sequence in accordance with an embodiment of the disclosure.

(5) FIGS. 4A-4C are schematic perspective views illustrating a process sequence in accordance with another embodiment of the disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

(6) FIG. 1A is a perspective view of a portion of a security document 1, such as a banknote or banknote blank, or a paper to be used to manufacture a passport, or part of a passport blank. The document comprises a document support 11 of paper, and a security element 2 embedded in the paper 11. The security element comprises an element support 21 in the form of a paper strip, covered with a layer of metal particles 22 which penetrates into said paper strip. The security element 2 extends in the machine direction throughout the document support 11, from one of the longer sides 12 to the opposite one of the longer sides of the document support 11, in parallel with the shorter sides 13 of the security support, one of which is shown in FIG. 1A. The document support may be printed, but the print is not shown in FIG. 1A, for simplicity.

(7) FIG. 1B schematically illustrates a different example of a security document support, in this case with three different security elements, one having a layer of randomly distributed metal particles, another one having a screen-like metal layer, and one comprising a compact metal layer. The layers, such as the compact metal layer, can optionally be perforated, such as with microperforations, to enhance capillarity. Also, for example, if the element substrate is a cellophane substrate, advantageously also the substrate is provided with perforations, to enhance capillarity.

(8) FIG. 3A is a top view of a security document, such as a banknote. The security document substrate 11 is a rectangular sheet having two shorter sides 12 and two longer sides 13. Embedded within the rectangular paper sheet is a security element 2, comprising a cellulose element substrate 21 partially covered with a metal layer 22. The security element has been inserted into the document substrate 11 during the manufacture of the paper sheet. For example, a large paper sheet or web can be manufactured in which several security strips 2 are inserted in parallel, and said larger sheet or web can then be cut to produce the individual document support. Due to the tolerances in the process of insertion of the security strips 12, and due to the tolerances in the cutting, the position of the security element 2 can vary in the X direction, that is, in the so-called cross direction, parallel with the longer sides 13. Thus, the security element as such may not be in perfect register with, for example, the shorter sides 12 or with matter printed on the document substrate, for example, printed symbols 5 (such as digit 2 in FIG. 3A). However, when applying the laser light to create the markings 3 (the numbers shaped by the recesses in the metallic layer 22 of the security element 2) as shown in FIG. 3B, this laser marking can be carried out to make sure that these symbols be in register with, for example, the short side 13 of the document substrate, and/or with the matter 5 printed on the document substrate, or with a watermark within the document substrate, etc., irrespective of a certain misalignment of the security strip 2 as such in the X direction, especially as the width of the security strip is large enough to allow for the marking of the numbers even if the security strip is slightly displaced in the X direction.

(9) The same applies to the alignment of the marking 3 of the security element in the Y direction, that is, the machine direction: as the addition of the marking 3, that is, the serial number, to the security element 2 takes place after insertion of the security strip 2 into the document substrate 11, it is possible to make sure that the digits of the serial number are placed correctly also in the Y direction, that is, in the axial direction of the security strip 2. This can be more difficult to achieve when a pre-marked security thread is inserted into a document substrate.

(10) FIG. 3B schematically illustrates how a laser source 4 is used to generate and direct a beam of laser light 41 towards the document support 11 and the security element 2. The laser light is projected onto the layer of metal particles 22 and sublimates the metal particles along the path scanned by the laser light beam, thereby creating recesses in said layer of metal particles 22. It can be seen how a marking in the form of series of recesses 3 shaped as digits has been established in the security element 2 embedded in the paper of the document support 11. Neither the document support 11 nor the element support 21 have been damaged, so the element support 21 is still embedded in the paper of the security support. The recesses 3 can easily be observed by transparency, but are not readily visible by reflectance, just as in the case with conventional security strips of the kind that, already before insertion into the document substrate, are provided with symbols/characters in the form or recesses in an opaque layer. In accordance with some embodiments of the disclosure, the recesses 3 can be placed in register with the sides of the document support 11, or in register with a feature printed on the surface of the document support, or in register with a watermark within the document support, etc.

(11) FIGS. 4A-4C illustrate another embodiment of the disclosure. FIG. 4A illustrates a security element 2 comprising a cellophane element substrate 21 with a metal layer 22. The cellophane substrate has been treated with laser light to create a plurality of perforations 9 to enhance capillarity so as to facilitate integration with the document substrate.

(12) In FIG. 4B, this security element 2 has been embedded in a paper document substrate 11, and a security document 1 has thus been formed, which in addition includes one or more printed symbols 5. When a passport is to be issued to a specific owner, and the owner's personal and biometric data are known, a QR dot code can be generated on the basis of the biometric data, and this code and other symbols 3 specific to the owner can be introduced in the security element by sublimating part of the remaining metal layer, as illustrated in FIG. 4C, where the QR dot code 3 is placed in register with the symbols 5 printed on the paper document substrate 11.

(13) The disclosure can, for example, be carried out in accordance with the following examples:

EXAMPLE 1

(14) Production of a Banknote Customized with a Serial Number.

(15) 1A.Manufacture of the Security Element:

(16) A suitable paper bobbin can be obtained from Papelera de Brandia, S. A., in accordance with the following specifications: basis weight 22 g/m.sup.2, thickness 48 microns, Bendtsen porosity (?4 sheets) 2600 ml/min, dry tensile strength 28N/15 mm and 17N/15 mm (machine direction and cross direction, respectively).

(17) This bobbin can subsequently be printed in a heliogravure printing machine manufactured by Giave, endowed with a printing cylinder manufactured by Artcyl and engraved by Ziraba. A suitable ink can be obtained from SICPA, with a viscosity of 32 s CP4 and containing aluminium metallic particles. The printing cylinder can be chemically engraved with a 36 lines/cm screen and a 34-micron cell depth with blocks so as to print, on the paper bobbin, 8 mm wide printed longitudinally continuous strips separated in the cross direction so that the distance in the cross direction between the centers of adjacent strips is 18 mm. This can be carried out with a machine speed of 80 m/min, a drying tunnel temperature of 45? C. and a winding tension of 150 N. Under these conditions, a 0.6 micron thick layer can be obtained in the printed area. Once the bobbin has been printed, it can be cut into 18 mm wide strips which can be wound on independent reels.

(18) 1B.Manufacture of the Document Substrate with Incorporation of the Security Element:

(19) A conventional paper machine with two cylindrical wire meshes 6 as shown in FIG. 2 can be used, together with an aqueous dispersion 7 of bleached and refined cellulose fibres. The paper machine can be adapted to manufacture a two-layer 11A and 11B security paper at a speed of 75 m/min to obtain a paper 11C with the following characteristics: basis weight 90 g/m.sup.2, thickness 95 microns, opacity 80%. The cellulose strips making up the security elements 2 are embedded between the two layers 11A and 11B, as shown in FIG. 2. The unwinding of the reels 8 with the cellulose strips making up the security elements 2 has to be carried out appropriately to achieve a correct embedding of the security elements 2. For example, the strips can be propelled with 1.75 bar compressed air so as to approach the strips up to 8 mm with respect to one of the two layers of the paper, whereafter contact take place automatically. Once the adhesion of the security element 2 between the two paper layers 11A and 11B has been achieved due to the phenomena of capillarity and transfer of fluids from the cellulose pulp, the tension in the security element strip is maintained at the same unwinding speed as the paper layers 11A and 11B, and with a 0.3 bar propelled air pressure to maintain the strip suspended in the air. Under the described conditions, it is not necessary to microperforate the security element prior to insertion, in order for it to be correctly embedded, as the printed metal strips are not very wide, and as the print does not eliminate the porosity of the paper, so that the strips continue to feature a sufficient capillarity.

(20) The obtained roll of security paper can subsequently be cut longitudinally and transversally in order to obtain paper sheets which can be used to print banknotes. These paper sheets can be configured with 5 cellulose security elements, embedded without increasing the paper thickness where they are embedded, and distanced, for example, 160 mm from each other.

(21) 1CManufacture of a Banknote Using the Security Paper:

(22) The paper sheets can be printed in silkscreen, intaglio, offset, etc. printing machines, and provided with backgrounds, images, numbers and details typical of a banknote design.

(23) Then, they can be subjected to the laser treatment of the disclosure. A Notamark machine can be used, manufactured by the company KBA-Giori, with a two-axis head with a Nd:YAG laser source which emits a 1060 nm pulsed laser light beam with an average power of 125 W and a 0.2 mm spot diameter. Under these conditions, the printed sheets can be processed at a speed of 10,000 sheets per hour and 40 banknotes per sheet. The laser radiation produces a sublimation of the metallic particles contained in the security element, producing a marking 3 in the form of recesses in the metal layer, recesses that correspond to the serial number of each banknote, such as 13 OCR numbers having a height of 2.8, as schematically illustrated in FIG. 3B. These recesses can be observed as lighter portions against a darker background when the banknote is held against a light, that is, when viewed by transparency; the darker background corresponds to the part of the metal particle layer that has not been sublimated by the laser source. The numbers can thus be observed by transparency in clear contrast with the rest of the surrounding 8-mm block on each banknote. As explained above, the numbers can be placed at a specific position; an example of a banknote obtained in this manner is shown on FIG. 3B. The banknote has a shorter side 12 and a longer side 13, and comprises a paper substrate 11 which has been printed with different symbols 5, and which contains, embedded within the substrate, the security strip 2 with the numbers 3 obtained by sublimating the metal layer, as described above.

EXAMPLE 2

(24) Production of a Passport with a Number and an Internal QR Code Including Biometric Data of the Owner.

(25) 2A.Manufacture of the Security Element with Metallic Particles:

(26) The starting material can be a cellophane or cellulose acetate film bobbin manufactured by Coopercel; the film can have a basis weight of 30 g/m.sup.2 and a thickness of 22 microns. This bobbin can subsequently be metallized on 100% of its surface with aluminium particles in a Leybold Optics ProM 1300 machine at a speed of 12 m/s and a pressure of 4?10.sup.?4 mbar. Under these conditions, a layer thickness with an optical density of 2.1 is obtained. The metallized film can subsequently be microperforated regularly with an Nd:YAG laser source adjusted at a wavelength of 10,000 nm and a power of 250 W, producing circular holes with a diameter of 0.2 mm and placed at a distance of 2 mm from each other, and with a staggered configuration. Once metallized, the bobbin can be cut longitudinally into 18 mm wide strips which can be wound in independent reels.

(27) 2B.Manufacture of the Document Substrate with Incorporation of the Security Element:

(28) A paper machine as described in Example 1 can be used. The paper machine can be adapted to manufacture a two-layer security paper at a speed of 85 m/min with the following characteristics: basis weight 85 g/m.sup.2, thickness 90 microns, opacity 80%. The insertion of the security element between the two layers of the paper can be carried out as suggested in FIG. 2. A device for the unwinding of the reels containing each security strip can be used in order to obtain the correct embedding of the security element. The strips can be propelled with 1.50 bar compressed air so as to approach the strips up to 8 mm with respect to one of the two layers of the paper whereafter contact takes place automatically. Once the adhesion of the security element between the two paper layers has been accomplished due to the phenomena of capillarity, transfer of fluids from the cellulose pulp and the dryness of the security element, the tension in the security element can be maintained at the same unwinding speed of the substrate manufacturing speed and with a 0.3 bar propelled air pressure to maintain the strips suspended. The obtained roll of security paper can subsequently be cut longitudinally and transversally in order to obtain the paper sheets out of which the passport blanks can be manufactured. The sheets can be configured with 6 cellulose strips embedded without increasing paper thickness in the area in which they are embedded, and positioned according to the desired layout of the pages of the passport

(29) 2C.Passport Manufacture:

(30) The paper sheets obtained in the previous step can be printed in a conventional manner, using silkscreen, intaglio, offset, etc. printing machines, with which the backgrounds, images, numbers and details typical to a passport design can be printed. Passport blanks can be produced and delivered to the authority or organization in charge of issuing the passport.

(31) When a passport is to be issued, and the owner's personal and biometric data are known, a QR dot code can be generated on the basis of the biometric data. This QR dot code can then be stored in the security element by means of an Nd:YAG laser source emitting a 1060 nm laser light beam with 125 W pulses and a 0.2 mm spot diameter, thus sublimating the metallic particles of the security element and thus removing part of the metal layer from the security element 2, thereby leaving a marking 3 in the form of a passport number and said QR dot code within the document substrate 11 of the security document 1, as schematically illustrated in FIG. 4C. Optionally, the QR dot code 3 can be placed in register with symbols 5 printed on the surface of the document support.

(32) In this text, terms generally have the meaning that they commonly have in the art of security documents, and are to be interpreted as they would be interpreted by the person skilled in the art of security documents and security paper. Regarding some of the terms used, a few clarifications are set out below:

(33) Paper: in this document, the term paper preferably refers to a material in sheet form having a basis weight of less than 250 g/m.sup.2 and comprising more than 50% by weight of cellulose fibres.

(34) Security document: The term security document refers to a document having particular characteristics which ensure its origin and authenticity. Security documents include documents used by public administrations and public organizations, as well as those used in the private sector, and which contain identification, authentication or anti-forgery means or devices. Security documents include identification documents (such as identification cards, passports, passes and the like) and value documents (such as bills, cheques, stamps, certificates and the like). A security document can be in the form of a security paper, an identification document, a banknote, a cheque, a stamp or a stamp-impressed paper, a label and a ticket. Sometimes, the term security article can be used to more generally include not only security documents but also objects that are not documents as such but that are provided with security means to guarantee their authenticity. In the present text, the expression security document should be understood in a broad sense, that is, not only as a finished document held by a final user, but also as encompassing intermediate products, such as blanks from which a final document can be produced, for example, a blank for producing a passport, said blank comprising the document substrate and, within it, the security element.

(35) Security element: the term security element relates to an element which is integrated into or applied to a security document or article for the purpose of authenticating it. The security element can be integrated into the substrate of a document, such as into a paper substrate, such as the paper substrate of a banknote or a paper substrate making up one or more pages of a passport or other identity document; this is frequently the case with security elements in the form of security threads, strips, ribbons, bands, patches, security fibres, watermarks, and elements producing tactile effects. Alternatively, the security element can be applied to the surface of the substrate of the security document; this is often the case with security elements in the form of holograms added to banknotes and credit cards, security inks, plastic sheets or other commonly used elements.

(36) Substrate of the security element or element substrate: Sometimes the material which provides a detectable or measurable security feature, such as an ink, a metal layer, etc., needs a carrier. The expression substrate of the security element or element substrate relates to said carrier, basically, the base material of which said element is made up. Frequently, the element substrate has a substantially laminar shape, such as the shape of a band or patch, although element substrates can also be fibrillar, in the shape of microparticles or in liquid dispersions such as inks. For example, security threads and holographic strips are usually manufactured using synthetic polymeric substrates, such as polyester or polypropylene substrates. It is also known in the art to use cellulose substrates, in the form of paper substrates (basically obtained by mechanical treatment of the cellulose fibres of natural origin) or cellophane substrates (basically obtained by chemical treatment of said natural cellulose fibres).

(37) Substrate of a document or document substrate: This term typically relates to the support used for the printing or manufacture of the security document, which can contain security features. For example, in the context of banknotes, passports, and other value or identity documents, the document substrate is frequently a paper substrate.

(38) Thread, band, ribbon and strip generally refer to substantially elongate elements, for example, of the type frequently arranged extending throughout the document substrate, from one side or edge to another side or edge, frequently the opposite side or edge. The term thread is not intended to imply any limitation in what regards the cross sectional shape of the element, whereas the terms band, ribbon and strip are generally intended to imply a substantially flat shape, that is, with a cross section being substantially larger in one direction than in the perpendicular direction.

(39) Sublimation: This term relates to a physical process in virtue of which a material changes to gas state from solid state without going through liquid state. In the context of this text, it applies to sublimation of material present in and/or on a security element substrate, such as metallic particles present in and/or on a the security element substrate, such as fixed on its surface by means of vacuum printing or metallization techniques.

(40) Customization: In the present text, customization of a security document relates to a certain stage of the manufacturing process of a security document in virtue of which the security document is endowed with a characteristic or feature which makes it original and unique compared to other documents of the same kind. Providing a passport or healthcare card with user identification data, or providing a banknote or cheque with a number, are examples of customization. The customization can involve the addition of a further security feature, for example, when the addition of a customization feature such as the number of a banknote is carried out in a way that involves a technical difficulty, whereby the presence of the customization feature helps to guarantee the authenticity of the document.

(41) In register: positioning in register implies that one item is positioned in a defined position in relation to another item. For example, a security element or a feature of a security element can be positioned in register with, for example, a feature of a substrate into which the security element is inserted, for example, in relation to an edge of the substrate, or in relation to a mark on or in the substrate, such as a printed mark on the surface of the substrate, or a watermark in the substrate. Since industrial processes always require tolerances, placement of one item in register with another item can render forgery more difficult. Also, the reduction of tolerances also makes it possible to increase the number of security elements that can be included in a security document, thus making it even more difficult to counterfeit the document.

(42) Marking: A marking is understood to include one or more marks, and a detectable marking can serve as a security feature and/or for the customization of a document. For example, a marking can comprise one or more symbols, such as letters, numbers or other symbols, or one or more patterns. Thus, a marking can, for example, include a serial number of a banknote or passport, and/or the name of an owner of an identity document, or an image or coded image of the owner, etc.

(43) In the figures, the dimensions are not intended to be in scale with typical real-life embodiments of the disclosure. Typically, the width/thickness ratio of the security element will be much larger, as the strips are typically very thin, for example, in the order of 50 microns, and rather wide, for example, having a width in the order of 10-35 mm.

(44) In this text, the term comprises and its derivations (such as comprising, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.

(45) In this present text, whenever intervals or ranges are given, the end points are included, unless the contrary is indicated.

(46) On the other hand, the disclosure is obviously not limited to the specific embodiment(s) described herein, but also encompasses any variations that may be considered by any person skilled in the art (for example, as regards the choice of materials, dimensions, components, configuration, etc.), within the general scope of the disclosure as defined in the claims.