Method for authenticating and / or identifying a security document

Abstract

The invention relates to a method for identifying and / or authenticating a security document comprising a paper substrate, wherein the substrate is analysed to detect the presence of one or more markers representative of the presence, in the substrate, of one or more compounds extracted from hardwood(s), and information relating to the identity and / or authenticity of the document is generated according to the nature and / or the proportion in the substrate of the one or more markers.

Description

Description Title of the invention: Method for authenticating or identifying a security document Technical field

[0001] The present invention relates to security documents and the identification or authentication thereof.

[0002] A "security document" means a valuable document, such as a means of payment, for example a banknote, a check, a bank card or a restaurant voucher, an identity document, such as an identity card, a visa, a passport or a driving license, a lottery ticket, a transport ticket or an entry ticket to cultural or sporting events. Prior art

[0003] To secure a document, it is common to use security features that are added to the paper during the production of the document.

[0004] It is thus known to use mineral pigments to authenticate or identify a paper, by giving it a specific signature. These mineral pigments are introduced during the wet part of the paper manufacturing process. They can consist of mixtures of rare earths, as described in publications EP0975460, WO9938702, W09938700, WO9939051, WO9938703, W02004111951, W02005035261, W02005035271, W02005035272, W02005036470, W02005036477, W02005036478 and W02005036479.

[0005] The use of such pigments poses several problems. On the one hand, their mineral nature contributes to the increase of the mineral load of the paper and therefore increases the ash content of the paper. In addition, an overload of mineral pigments tends to degrade the mechanical resistance of the paper. On the other hand, as with other opacifying mineral loads (for example titanium dioxide), their retention during drainage is imperfect and their loss in the water under the canvas can be significant and, as these are sometimes very expensive markers, this can have a significant economic impact. In some cases, moreover, due to the toxicity inherent in their chemical nature, their use can pose environmental problems. Finally, their detection often requires the use of specific high-tech electromagnetic detectors, which complicates the authentication of the document.

[0006] Furthermore, it is known to use microscopic observation techniques to identify and quantify specific synthetic or natural fibers of a paper substrate. Publications W02015 / 200575, W02015 / 200577 and W02015 / 200572 describe such methods. In certain situations, and especially in the case of mixing with other fibers such as cotton fibers, paper refining operations can make the identification of these "special" fibers very difficult and require analysis by a particularly experienced operator. The similarity in the fibrous nature of a particular species with the other fibrous components of the paper, which have a fine and elongated shape, contributes to this difficulty.

[0007] There is a need to further increase document security, particularly by simplifying their authentication and / or identification. Summary of the invention

[0008] The invention aims to meet this need and achieves this, according to one of its aspects, by means of a method for identifying and / or authenticating a security document comprising a paper substrate, in which the substrate is analyzed to detect the presence of one or more markers representative of the existence in the substrate of one or more compounds extracted from hardwood(s) and information concerning the identity and / or authenticity of the document is generated as a function of the nature and / or proportion in the substrate of said marker(s).

[0009] A "hardwood-extracted compound" includes cellulose and hemicellulose fibers and vessels. The vessels and fibers are distinguished by their size. Fibers are generally longer and thinner than vessels. The compound may be a solid compound. The compound may be introduced in the form of a paste. Hardwood fibers are generally short and thin. The fibers and vessels include cellulose or hemicellulose.

[0010] By "deciduous" we mean a tree that produces well-developed leaves, as opposed to conifers or resinous trees. Deciduous trees can lose their leaves cyclically, especially in autumn, in which case we speak of a deciduous tree. The leaves of deciduous trees are generally broad. Unlike deciduous trees, conifers have needle-like leaves that renew themselves gradually, making them evergreen. Conifers therefore always have the same appearance. Conifers can also be called conifers. The following trees are examples of deciduous trees: birch, hornbeam, chestnut, oak, eucalyptus, beech, sweet gum, nyssa, poplar, and American tulip tree.

[0011] The advantage of using a hardwood-extracted compound in a paper substrate is twofold. On the one hand, the hardwood-extracted compound, due to its cellulosic fibrous nature, is well suited to the manufacture of a paper substrate. The resulting paper substrate thus has good mechanical strength. On the other hand, the markers representative of the existence in the substrate of one or more hardwood-extracted compounds are easily identifiable markers. Identification and / or authentication can be done without difficulty, particularly by visual observation at low magnification.

[0012] In addition, the method according to the invention has the advantage of being safe for health and the environment, compared to the use of certain mineral pigments. It therefore does not require the detection of a non-natural marker which could be toxic and / or harmful to the environment.

[0013] The process according to the invention is economical since it only requires the use of a compound extracted from hardwood(s). However, hardwoods are widespread trees.

[0014] The paper substrate may comprise cellulosic fibres other than hardwood fibres. In particular, the substrate may comprise cotton fibres, especially when the aim is to produce banknotes.

[0015] The nature and / or proportion of one or more compounds extracted from hardwood(s) in the composition of the substrate can be varied in order to produce security documents with a unique signature. For example, compounds extracted from two different hardwoods can be mixed to produce the paper substrate and this substrate can be distinguished from another substrate comprising, for example, the same compounds in different proportions or other compounds extracted from hardwood(s).

[0016] Substrate analysis can be performed with and / or without magnification, including with the naked eye, for example after performing a specific staining. Substrate analysis with magnification is preferably performed with a microscope. Substrate analysis is preferably performed without a specific electromagnetic detector, for example under white light.

[0017] The method according to the invention thus has the advantage of being simple to implement. It does not require any devices other than an optical microscope to detect the marker(s). It is therefore economical and quick to implement.

[0018] The marker(s) representing the existence in the substrate of one or more compounds extracted from hardwood(s) can also be detected without magnification. The security document can thus be authenticated and / or identified by an uninformed observer ("the man in the street").

[0019] The hardwood tree(s) whose presence is sought in the paper preferably consists of at least one of the following species: birch, hornbeam, chestnut, oak, eucalyptus, beech, sweet gum, nyssa, poplar, American tulip tree.

[0020] The hardwood tree(s) preferably belong(s) to the eucalyptus family. They are in particular made up of at least one of the following eucalyptus varieties: eucalyptus globulus, eucalyptus camaldulensis, eucalyptus rostrata, eucalyptus citriodora, eucalyptus cordata, eucalyptus deglupta, eucalyptus gundal, eucalyptus gunnii, eucalyptus pauciflora, eucalyptus radiata, eucalyptus regnans, eucalyptus sideroxylon.

[0021] Eucalyptus trees have the advantage of being fast-growing trees that can grow easily in various regions of the world. They are therefore an easily accessible resource for making paper substrate.

[0022] Preferably, at least one of the markers consists of broadleaf vessels. In particular, at least one of the markers consists of eucalyptus vessels.

[0023] The advantage of hardwood vessels is that they have an easily identifiable morphology, which makes it possible to distinguish fibers of compounds extracted from hardwood from cotton fibers when analyzing the substrate.

[0024] Furthermore, their morphology also has the advantage of providing them with a large specific surface area which contributes to their retention, particularly without loss, during the manufacture of the paper substrate. The vessels of the compounds extracted from hardwood(s) can therefore contribute to the mechanical reinforcement of the paper substrate, in the same way as hardwood(s) and cotton fibers.

[0025] Due to their organic and cellulosic composition, these vessels do not contribute significantly to ash generation.

[0026] In the method according to the invention, the shape of the vessels is preferably analyzed. Information regarding the identity and / or authenticity of the document can be generated at least on the basis of the result of this analysis.

[0027] When analyzing vessel shape, at least a ratio of vessel length to vessel width is preferably calculated.

[0028] It is preferably determined during the analysis whether the said ratio is between 0.7 and 4.5, better between 0.8 and 4 (particularly for eucalyptus), even better between 0.9 and 3.5, better between 1 and 3, better between 1.1 and 2.5, better between 1.2 and 2, for example of the order of 1.8.

[0029] The length of a vessel, in particular a eucalyptus vessel, is preferably between 100 and 550 pm, better between 120 and 500 pm, better between 150 and 450 pm, better between 200 and 350 pm, for example of the order of 290 pm.

[0030] The width of a vessel, in particular a eucalyptus vessel, is preferably between 50 and 400 pm, better between 75 and 350 pm, better between 100 and 300 pm, better between 100 and 250 pm, for example of the order of 160 pm.

[0031] When implementing the method according to the invention, vessels having a substantially rectangular shape in cross-section are preferably counted.

[0032] Hardwood vessels, especially eucalyptus vessels, have a roughly rectangular, or even square, cross-section. They are also quite thick and quite short. They are therefore very different from the usual cotton fibers, which are elongated and thin. This makes them easier to count during substrate analysis.

[0033] To carry out the analysis, the substrate can be brought into contact with a substance suitable for selectively staining at least one of said markers. This selective staining can take place before counting the vessels. The substance can in particular be chosen to stain the vessels and the fibers, especially cotton, differently.

[0034] This selective staining makes it easier to identify markers, particularly vessels. Identification after staining can therefore be done with or without magnification.

[0035] The substance suitable for selectively coloring at least one of said markers is preferably a Herzberg reagent solution.

[0036] The use of Herzberg reagent (or zinc chloroiodide) on a substrate composed primarily of cotton fibers and one or more compounds extracted from hardwood(s) makes it possible to color the compound(s) extracted from hardwood(s) a first color, for example blue, and the cotton fibers a second color, distinct from the first, for example red.

[0037] Elements with the first color can be seen without magnification, which allows the presence of one or more compounds extracted from hardwood(s) to be detected. The specific coloration therefore allows for a first authentication and / or identification that can be carried out with the naked eye.

[0038] A more precise analysis with magnification, for example under a microscope, can then be carried out. The aim is then to analyze the morphology of the markers, for example the vessels, to determine the hardwood species used. Due to their very characteristic morphology, eucalyptus vessels are particularly easy to identify.

[0039] During the analysis, the colored markers are preferably counted.

[0040] Preferably, the markers are counted on a given surface of the analyzed substrate and the proportion of compounds extracted from hardwood(s) in the substrate manufacturing paste is deduced.

[0041] The marker(s) preferably appear in isolation. They can be directly identifiable on the surface of the paper substrate, with or without magnification. It is then not necessary to crush and / or disintegrate the security document to carry out its analysis.

[0042] The substrate analysis is thus preferably carried out without destroying the document. For example, no sample is taken from the document. The marker(s) being analyzed may be present on the document during this analysis. In the case of a banknote, for example, it is examined under a microscope to determine the presence and / or content of the markers.

[0043] At least one of the markers used for implementing the identification and / or authentication method according to the invention may be present in a small proportion in number compared to the other constituents extracted from the hardwood and present in the paper. For example, in the case where the marker is made up of vessels, there may be 10 times fewer vessels than fibers in the compound extracted from hardwood which is integrated into the paper during its manufacture, better still 50 times fewer vessels than fibers, better still 100 times fewer vessels than fibers, or even 1000 times fewer vessels than fibers. Security element

[0044] It is also possible to check the presence of one or more additional conventional security elements on the document.

[0045] Among these additional security elements, some are detectable by eye, in daylight or artificial light, without the use of any special device. These security elements include, for example, colored fibers or planchettes, fully or partially printed or metallized security threads, a secure knitted structure, a security film, a watermark, an optically variable element (known as "OVD"), in particular a hologram. These security elements are called first-level security elements.

[0046] Other types of additional security features are detectable only using a relatively simple device, such as a lamp emitting in the ultraviolet (UV) or infrared (IR) range. These security features include, for example, fibers, planchettes, strips, threads, or particles. These security features may or may not be visible to the naked eye, for example, being luminescent under illumination from a Wood lamp emitting at a wavelength of 365 nm. These security features are called second-level security features.

[0047] Other types of additional security features require a more sophisticated detection device for their detection. These security features are, for example, capable of generating a specific signal when they are subjected, simultaneously or not, to one or more external excitation sources. Automatic signal detection allows the document to be authenticated, if necessary. These security features include, for example, tracers in the form of active materials, particles or fibers, capable of generating a specific signal when these tracers are subjected to optronic, electrical, magnetic or electromagnetic excitation. These security features are called third-level security features.

[0048] The additional security element(s) present within the paper according to the invention or the secure document according to the invention may have first, second or third level security characteristics.

[0049] Substrate analysis is preferably done by automatic image analysis, for example via a computer, in particular a computer connected to the optical microscope used for the analysis. Security document

[0050] The invention also relates, independently or in combination with the above, to a security document comprising a paper substrate comprising cellulosic fibers and one or more compounds extracted from hardwood(s).

[0051] The addition of compounds extracted from hardwood(s) in the composition of the paper substrate of the security document makes it possible to increase the mechanical strength of the paper. The fibrous and cellulosic nature of the compounds extracted from hardwoods contributes to the development of the mechanical strength of the paper substrate. The internal cohesion, the dry and wet tensile strength of the security document according to the invention are improved by the presence of compounds extracted from hardwoods. The The level of durability of the paper is thus increased, which makes it possible to increase the circulation life of the security document, particularly in the case of a banknote.

[0052] Hardwood fibers, especially eucalyptus fibers, have the advantage of being short and thin. In addition, they have a high specific surface area, especially compared to cotton fibers, which are traditionally used in the manufacture of paper substrates.

[0053] The substrate preferably comprises between 2 and 50%, by mass relative to the mass of the substrate, of one or more compounds extracted from hardwood(s), better still between 3 and 40%, better still between 5 and 30%. The substrate is preferably weighed at a relative humidity level of 50% at room temperature (20°C).

[0054] The substrate may in particular contain between 0.1 and 1% of hardwood vessel(s), in particular eucalyptus, per unit of surface area.

[0055] The substrate may comprise at least 50% by mass of cotton fibers, relative to the total mass of the substrate.

[0056] The hardwood tree(s) preferably belong to the eucalyptus family, and may be chosen in particular from the following eucalyptus species: eucalyptus globulus, eucalyptus camaldulensis, eucalyptus rostrata, eucalyptus citriodora, eucalyptus cordata, eucalyptus deglupta, eucalyptus gundal, eucalyptus gunnii, eucalyptus pauciflora, eucalyptus radiata, eucalyptus regnans, eucalyptus sideroxylon.

[0057] The compounds extracted from eucalyptus have the advantage of containing hemicelluloses which, due to the reactivity of their carboxylic groups, allow active collaboration with resins, in particular with a polyamide-polyamine-epichlorohydrin resin (PAAE resin), which improves the development of the wet strength of the paper substrate.

[0058] The substrate can thus advantageously contain both compounds extracted from eucalyptus, in particular eucalyptus fibers and vessels, and a resin conferring wet strength to the paper, preferably a PAAE resin.

[0059] One or more security elements may be integrated or added to the substrate, this or these security elements being of first, second and / or third level, as detailed above, being chosen for example from: a security thread, a planchette, a security film, a watermark, an optically variable element (called “OVD”), in particular a hologram, a tracer in the form of a material capable of generating a specific signal when subjected to electrical, magnetic or electromagnetic excitation, in particular optical, for example a luminescent agent under UV or IR, intaglio printing, or an optically variable ink.

[0060] In exemplary embodiments, the substrate comprises compounds extracted from at least two different hardwood species, in particular eucalyptus and on the other hand, a hardwood chosen from: birch, hornbeam, chestnut, oak, beech, sweetgum, nyssa, poplar, American tulip tree. Brief description of the drawings

[0061] The invention may be better understood by reading the description which follows, non-limiting examples of its implementation, and by examining the appended drawings, in which:

[0062] [Fig 1] Figure 1 is a schematic view of an example of a security document according to the invention,

[0063] [Fig 2] Figure 2 is a block diagram of steps of an example identification and / or authentication process,

[0064] [Fig 3] Figure 3 is a microscope view of a substrate containing a compound extracted from hardwoods after selective staining,

[0065] [Fig 4] Figure 4 is a view similar to Figure 3 with a higher magnification,

[0066] [Fig 5] Figure 5 is a photograph of four substrates containing a hardwood-extracted compound in increasing proportions after selective coloring of the vessels and surroundings for counting. Detailed description

[0067] Figure 1 shows a security document 10 which comprises a substrate 11 in which a security element 12 is integrated or on which is attached.

[0068] This substrate 11 is fibrous. It may comprise the fibres and additives conventionally used in the papermaking field, in particular cellulose fibres. The substrate may comprise a mixture of long and short cellulose fibres. This substrate 11 comprises one or more compounds extracted from hardwoods, namely hardwood fibres and vessels.

[0069] The substrate may comprise a single fibrous layer or several fibrous layers (also called jets) assembled after formation, particularly in the wet phase.

[0070] The substrate may include one or more security structures obtained during manufacturing, and the substrate may in particular include a fibrous layer bearing a watermark.

[0071] The fibrous layer(s) of the substrate may be produced on a flatbed or cylinder-form paper machine, and the watermark(s) may be produced in the wet portion using conventional methods known to those skilled in the art.

[0072] At least one fibrous layer of the substrate, or even the substrate itself, may have a grammage (according to ISO 536 standard) of between 60 and 120 g / m 2 , preferably between 70 and 90 g / m 2 .

[0073] At least one fibrous layer of the substrate, or even the substrate itself, may have a thickness (according to ISO 534 standard) of between 60 and 120 pm, preferably between 70 and 110 pm, for example approximately 110 pm.

[0074] The block diagram in Figure 2 shows steps of an example of an identification and / or authentication method according to the invention.

[0075] First of all, in order to proceed with the analysis of the security document, during a first step El, the document is immersed in a Herzberg reagent solution. This first step El allows the selective coloring of the desired markers.

[0076] Then, in a second step E2, the document is left to dry. Once the document is dry, it can be observed using an optical microscope (step E3).

[0077] The presence of a compound extracted from hardwood is sought in the substrate of the document.

[0078] The study of the morphology of the detected markers makes it possible to determine the nature of the hardwood used in the composition of the substrate. This allows for an initial identification of the document.

[0079] The number of colored markers on a given surface of the document is then counted using the microscope (step E4). From this count, an estimate of the mass percentage of the hardwood-extracted compound in the composition of the document's substrate can be deduced. This estimate makes it possible to identify the document.

[0080] Following the analysis, and in particular following the count, information can be generated concerning the identity and / or authenticity of the document (step E5).

[0081] In the example of figures 3 to 5, the markers representative of the existence in the paper substrate of one or more compounds extracted from hardwood(s) are eucalyptus vessels.

[0082] The substrates shown in Figures 3 to 5 were selectively stained by soaking in a Herzberg reagent solution. The compounds extracted from hardwoods, i.e., vessels and fibers, then stain blue and can be distinguished from other elements of the substrate.

[0083] As seen in Figure 3, Eucalyptus 1 vessels differ from Eucalyptus 2 fibers by their wider and shorter shape.

[0084] The length L and width / of a eucalyptus vessel are visible in Figure 4. The length L is for example of the order of 290pm. The width / is for example of the order of 160pm.

[0085] Figure 5 shows four substrates comprising an increasing mass proportion, from left to right, of compounds extracted from eucalyptus. Substrate S1 comprises 5% by mass of eucalyptus pulp, substrate S2 comprises 10% by mass of eucalyptus pulp, substrate S3 comprises 20% by mass of eucalyptus pulp, substrate S4 comprises 30% by mass of eucalyptus pulp.

[0086] Eucalyptus 1 vessels were selectively stained with Herzberg's reagent. This photograph shows that the greater the mass proportion of eucalyptus-extracted compounds in the substrate, the greater the number of vessels. This correlation is also established in Examples 2 and 3 below. Examples

[0087] Example 1

[0088] The effect of introducing 5, 10, 20 and 30% by mass of eucalyptus pulp relative to the total mass of pulp as a replacement for part of the cotton pulp (cotton 1, cotton 2) on the mechanical properties of the paper substrate is evaluated.

[0089] The resulting substrates undergo surfacing in a size press.

[0090] As a control, a substrate containing only cotton fibers and no compounds extracted from eucalyptus was used.

[0091] Zeta potential is measured with a “System Zeta Potential” device, model Mütek SZP-06 from BTG.

[0092] To assess dry tensile strength, including dry breaking length (or "dry breaking length"), the length at which sheets break under their own weight can be measured according to ISO 1924-2.

[0093] To assess wet tensile strength, including wet breaking length (or "wet breaking length"), the length at which sheets break under their own weight can be measured according to ISO 3781.

[0094] Wet strength (WST) is defined as the ratio of wet breaking length to dry breaking length according to the following formula:

[0095] [Math 1] Wet breaking length RE H — - ; - - - 777 -

[0096] Breaking length at 1 dry state

[0097] Internal cohesion (or resistance to delamination) is measured using a SCOTT device, model B, No. ESO33, according to Tappi standard 569 om-09

[0098] The results of the evaluations are presented in the table below. The percentages of cotton 1, cotton 2 and eucalyptus pulp are percentages by mass relative to the total mass of pulp. [Table 1]

[0099] In the table above: “MD” means “direction of travel”, “CD” means “cross direction” and “Avg.” means “average”.

[0100] It is observed that the internal cohesion, dry tensile strength and wet tensile strength of the substrates containing eucalyptus are improved compared to the control substrate which contains only cotton fibers.

[0101] The Zeta Potential (PZ) of the substrates is also measured. It is observed that it gradually changes from 2.2 mv to -3.2 mv, -5.3 mv and -10.5 mv for eucalyptus levels increasing respectively from 5% to 10%, to 20% and to 30% by mass. This reflects the increasing presence of associated hemicelluloses from eucalyptus, thus increasing the fixation potential of the PAAE resin.

[0102] Comparing the substrate comprising 20% ​​by mass of eucalyptus-extracted compound with the control substrate not comprising eucalyptus-extracted compound, it is found that with the substrate comprising eucalyptus, internal cohesion is improved by 33.2%, rigidity is improved by 23.1%, dry traction is improved by 5%, and wet traction is improved by 14.5%.

[0103] The introduction of compounds extracted from eucalyptus into the substrate therefore makes it possible to improve the mechanical resistance of this substrate.

[0104] Furthermore, the above results show that the presence of eucalyptus fibres does not unduly alter the colour of the paper used for the security document.

[0105] Example 2

[0106] In this example, we are trying to count eucalyptus vessels on paper substrates containing different mass proportions of compounds extracted from eucalyptus by direct observation of the substrate, i.e. without the use of a microscope. The substrate analyzed comprises a cotton pulp containing cotton fibers of two different references mixed in equal mass proportions. The substrate also contains a portion of eucalyptus pulp. The compositions of the different paper substrates used are shown in the following table. The percentages indicated are mass percentages. [Table 2]

[0107] Each substrate is soaked in a Herzberg reagent solution for at least 30 seconds. Areas of the substrate corresponding to the eucalyptus vessels turn blue-violet. The substrate is then allowed to air dry.

[0108] The eucalyptus vessels that are then colored can be easily counted. The results of the counts carried out for each of the substrates are shown in the table below. [Table 3]

[0109] There is a correlation between the number of eucalyptus vessels counted and the proportion of eucalyptus-extracted compounds in the substrate. The higher the proportion of eucalyptus-extracted compounds in the substrate, the greater the number of vessels counted.

[0110] Example 3 [OR I] In this example, we are trying to count eucalyptus vessels on paper substrates containing different mass proportions of compounds extracted from eucalyptus. The substrate analyzed comprises a cotton pulp containing cotton fibers of two different references mixed in equal mass proportions. The substrate also contains a portion of eucalyptus pulp. The compositions of the different paper substrates used are indicated in the following table. The percentages indicated are mass percentages. [Table 4]

[0112] We start by preparing dispersions of the substrates as follows:

[0113] 1 - Cut and weigh a 4 x 4 cm square of each substrate. Then cut the square into pieces of approximately 1 x 1 cm. Then transfer them to the bowl of a mixer.

[0114] 2 - Add 50 ml of demineralized water and grind for 3 minutes at maximum speed.

[0115] 3 - Rinse the mixer bowl and lid with demineralized water and transfer the resulting fibrous suspension into a beaker. Then dilute with approximately 200 mL of rinsing water.

[0116] 4 - Filter through a sieve with a 53 µm square mesh. Then rinse and transfer to a beaker and dilute with approximately 50 mL of rinsing water. This removes the fillers, particularly titanium dioxide (TiO2).

[0117] 5 - Place the beakers in an oven at 105°C to evaporate the water and obtain a slightly damp paste.

[0118] The slides are then prepared to count the vessels:

[0119] 1 - Place a few drops of Herzberg reagent on a microscope slide (26 x 76 mm). Using two curved dissecting needles, take a little paste and disperse it in the reagent until a homogeneous distribution is obtained, without fiber agglomerates, also called matons. Cover with a coverslip (24x32 cm). This prepares about ten slides.

[0120] 2 - Place the slide on the stage of the optical microscope (Olympus / transmitted light / X 5 objective)

[0121] 3 - Using the cross-movement of the stage, the blade is moved in order to cover it completely without overlapping the observation fields.

[0122] 4 - Count the eucalyptus vessels in each circular field.

[0123] The results of the count are presented in the following table: [Table 5]

[0124] There is a correlation between the number of eucalyptus vessels counted and the proportion of eucalyptus-extracted compounds in the substrate. The greater the proportion of eucalyptus-extracted compounds in the substrate, the greater the number of vessels counted. Counting the number of eucalyptus vessels therefore makes it possible to estimate the mass proportion of eucalyptus in the composition of the substrate. This allows a security document made from a substrate containing a portion of eucalyptus to be identified and / or authenticated.

[0125] The substrate will be authenticated, for example, when a mass proportion of eucalyptus corresponding to that expected for an authentic substrate is counted.

[0126] The substrate can be identified, for example, based on the nature of the hardwood used, if several documents exist with different varieties of hardwood.

Claims

Claims 1. Method for identifying and / or authenticating a security document comprising a paper substrate, in which the substrate is analyzed to detect the presence of one or more markers representative of the existence in the substrate of one or more compounds extracted from hardwood(s), and information concerning the identity and / or authenticity of the document is generated as a function of the nature and / or proportion in the substrate of said marker(s).

2. Method according to the preceding claim, the analysis of the substrate being carried out with and / or without magnification, in particular with the naked eye.

3. Method according to one of the preceding claims, in which the hardwood(s) consist of at least one of the following species: birch, hornbeam, chestnut, oak, eucalyptus, beech, sweetgum, nyssa, poplar, American tulip tree, preferably eucalyptus.

4. Method according to any one of the preceding claims, in which the hardwood tree(s) belong(s) to the eucalyptus family, being in particular constituted by at least one of the following varieties of eucalyptus: eucalyptus globulus, eucalyptus camaldulensis, eucalyptus rostrata, eucalyptus citriodora, eucalyptus cordata, eucalyptus deglupta, eucalyptus gundal, eucalyptus gunnii, eucalyptus pauciflora, eucalyptus radiata, eucalyptus regnans, eucalyptus sideroxylon.

5. Method according to any one of the preceding claims, at least one of the markers being constituted by leafy vessels.

6. Method according to the preceding claim, in which the shape of the vessels is analyzed and said information is generated at least on the basis of the result of this analysis.

7. Method according to the preceding claim, in which during the analysis of the shape at least one ratio is calculated between the length of the vessels and their width.

8. Method according to the preceding claim, in which it is determined during the analysis whether said ratio is between 0.7 and 4.5, better still between 0.8 and 4, even better still between 0.9 and 3.5, better still between 1 and 3, better still between 1.1 and 2.5, better still between 1.2 and 2, for example of the order of 1.

8. Method according to any one of the three immediately preceding claims, in which the vessels having a substantially rectangular shape in cross-section are counted. Method according to any one of the preceding claims, in which to carry out the analysis the substrate is brought into contact with a substance suitable for selectively coloring at least one of said markers. Method according to the preceding claim, in which said substance is a Herzberg reagent solution. Method according to one of the two immediately preceding claims, in which during the analysis the colored markers are counted. Method according to any one of the preceding claims, the analysis of the substrate being carried out without destruction of the document.Method according to any one of the preceding claims, in which the presence on the document of one or more security elements is also verified, the security element(s) being chosen in particular from: a security thread, a planchette, a secure knitted structure, a security film, a watermark, an optically variable element (known as "OVD"), in particular a hologram, a tracer in the form of a material capable of generating a specific signal when subjected to electrical, magnetic or electromagnetic excitation, in particular optical. Method according to any one of the preceding claims, the analysis of the substrate being carried out by automatic image analysis.Method according to any one of the preceding claims, the analyzed substrate comprising between 2 and 50%, by mass relative to the mass of the substrate, of one or more compounds, preferably vessels, extracted from hardwood, in particular eucalyptus, better between 3 and 40%, better between 5 and 30%. Security document comprising a paper substrate comprising between 2 and 50%, by mass relative to the mass of the substrate, of one or more compounds, preferably vessels, extracted from hardwood, in particular eucalyptus, better between 3 and 40%, better between 5 and 30%. the security document comprising one or more security elements integrated or added to the substrate. Security document according to the preceding claim, the security element(s) being chosen from: a security thread, a planchette, a secure knitted structure, a security film, a watermark, an optically variable element (known as "OVD"), in particular a hologram, a tracer in the form of a material capable of generating a specific signal when subjected to electrical, magnetic or electromagnetic excitation, in particular optical. Security document according to one of the two preceding claims, the eucalyptus being chosen from the following eucalyptus species: eucalyptus globulus, eucalyptus camaldulensis, eucalyptus rostrata, eucalyptus citriodora, eucalyptus cordata, eucalyptus deglupta, eucalyptus gundal, eucalyptus gunnii, eucalyptus pauciflora, eucalyptus radiata, eucalyptus regnans, eucalyptus sideroxylon.Security document according to any one of claims 17 to 19, the security document being chosen from: a banknote, a check, a bank card or a restaurant voucher, an identity document, such as an identity card, a visa, a passport or a driving license, a lottery ticket, a transport ticket or an entry ticket to cultural or sporting events. Security document according to any one of claims 17 to 20, the substrate comprising compounds extracted from at least two different hardwood species, in particular on the one hand eucalyptus and on the other hand a hardwood chosen from: birch, hornbeam, chestnut, oak, beech, sweet gum, nyssa, poplar, American tulip tree.

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