• 专利附录
  • 专利说明
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    • 专利摘要:
    PROTECTION SHEET UNDERSTANDING A MULTIPLE TONE WATERMARK, DOCUMENT, METHOD FOR MANUFACTURING A PIECE TO FORM A MULTIPLE TONE WATERMARK, RELATED PIECE AND USE OF THE REFERRED PIECE. The present invention relates to the paper field and relates to a sheet including a high-contrast, high-definition multi-tone watermark having areas of pronounced brightness. Such a watermark is obtained particularly by means of a piece (4) including a surface (5) having a raised area and perforations (6). The perforations (6) are such that making a sectional cut of them, at a given distance from the drainage surface, directly depend on the said distance. The present invention also relates to the method of manufacturing said piece that is used to form such a watermark, for the piece itself, and to the use of said piece, when forming a watermark.
    公开号:BR112012023906B1
    申请号:R112012023906-6
    申请日:2011-03-23
    公开日:2020-11-10
    发明作者:Pierre Doublet；Ivan Thierry
    申请人:Oberthur Fiduciaire Sas；
    IPC主号:
    专利说明:

    The present invention relates to the field of papermaking and more particularly to a watermark. This refers to a sheet comprising a watermark and a document comprising such sheet, the method for making a part used to form such a watermark, the part obtained according to the said method of manufacture and the use of this piece during the formation of the watermark.
    Watermarks are commonly used to make documents that have a specific content and value. These are, in particular, property titles, certificates, diplomas, ballots, passports, identity cards, driving licenses, checks, tickets to cultural or sporting events or letterhead.
    Watermarks are formed during papermaking, in particular by modifying the drainage of the fibrous suspension from which the paper is made. Thus, a drainage fabric generally comprises flat and solid parts, therefore impermeable, commonly known as galvanizing or electrotypes. Such part 1 is represented in figure 1.
    By way of observation, a drainage tissue (also known as forming tissue) generally consists of at least two overlapping individual tissues.
    These pieces or galvanies locally modify the deposition of the fibers of said fibrous suspension in relation to regions not equipped with said pieces. The effect obtained is a clear watermark that can be easily seen in transmitted light. The watermark obtained has regions that are clear, uniform, that is, having a unique level of gray, and very pronounced. The expression "can be seen in transmitted light" is understood as an element (here the watermark) that is visible, especially to the naked eye,
    when placed between the observer's eye and a light source so that the eye perceives the rays of the light source through the observed elements.
    As an observation, the watermarks are visible in transmitted light, but they are not, or are not very, visible in reflection, that is, when the eye of the observer and the light source are placed on one and the same side of the element to be observed, the eye thus perceiving the rays of the light source reflecting on the observed element.
    Additional technological developments have made it possible to obtain watermarks comprising various shades in gray levels. These watermarks, known as multi-tone watermarks or shaded watermarks, are usually obtained by embossing the drainage fabric 2 for example represented in figure 2, and in particular at least one of the fabrics , preferably the upper fabric, along an embossed relief 3 composed of minorized portions 32 and enlarged portions 31. Such watermarks consist of regions that are lighter and regions that are darker than the unmarked portion d 'water (or tissue paper portion) from the fibrous substrate. These lighter and darker regions are respectively known as the watermark lights and darks.
    Multi-tone watermarks are generally obtained according to the following papermaking process: a fibrous suspension comprising water and fibers, optionally added to what are fillers, in particular retention agents, opacifiers, pigments, antibacterial agents and / or antifungal agents, is brought into contact with said drained fabric embossed. During drainage, a greater amount of fiber is deposited in the minorized portions than in enlarged portions, whose portions are minorized or increased with respect to the plane of the drainage tissue. The "wet" sheet obtained by draining said fibrous suspension in said draining fabric is subsequently pressed when dried according to the standard papermaking process. As an observation, additional treatments can be applied to or on the sheet during its manufacture, especially through operations such as impregnations, surface applications, coating operations and / or softening operations. By observing in transmitted light the leaf watermark thus obtained, several levels of gray are distinguished, each level of gray corresponding to a level of relief, diminishing or increasing, of the referred pieces.
    The manufacture of a drainage fabric comprising embossing to form multi-tone watermarks is time consuming and is therefore very expensive. This is because such drainage fabric can, for example, comprise several hundred of said parts, which must all be identical to allow identical watermarks to be obtained. The manufacture of these parts provided with relief requires special attention, in particular in relation to their dimensions and the possibility of reproducing their manufacturing methods. The drain fabric of a cylinder mold paper machine for forming watermarks generally comprises at least two overlapping metallic fabrics. It is therefore sensitive to mechanical shocks. Such shocks occur in particular in most exposed portions, for example, the enlarged portions of an embossing. They damage the drainage tissue and irretrievably interrupt the formation of the paper sheet, and at least a portion of the drainage tissue, for example the outer tissue, must then be manufactured again.
    Of course, the limited service life of a drainage fabric is one of the factors that influence the total cost of producing a watermarked paper.
    Recently, the order DE 10 2005 042 344 proposed the fact of inserting locally, in an embossing of the external fabric of the drainage fabric, a flat perforated piece that follows the relief of the embossing. The perforations of said piece are micro perforations. The advantage described in this application lies in the creation of multi-tone watermarks comprising light regions. Order DE 10 064 006 describes how the regions of the drainage fabric comprising those perforated parts that make it possible to obtain these very clear regions can be provided with additional parts by means of a shaped memory material. Orders DE 10 2006 058 513 and WO 2008/071325 describe a part used to form watermarks. This injection-molded plastic part is provided with a relief comprising perforations made using a laser. Thus, said perforations are formed in a profiled piece, that is, a piece comprising a relief on one of its faces, and starting from the opposite face of the profile. According to a variation, the perforations become thinner when going from the rear face (lateral of drainage tissue) towards the profiled face. It is explained that the perforations guarantee a free flow of the fibrous suspension and that the regions of said piece having a greater thickness allow the formation of fine points on the paper.
    A disadvantage of this method relates to the precision of the perforation and, in particular, its diameter on the profiled face, which strongly depends on the properties of the material used, and in particular on the nature of the plastics and the thickness of the material. The drilling accuracy is therefore difficult to control. The laser forms holes that contract when going towards the profiled face. Due to the physical process used when drilling a plastic using a CO2 laser, the shape of the perforation is, in the longitudinal direction of the channel, more or less conical on the laser side due to the Gaussian energy distribution of the laser beam, and the larger the channel (the greater the thickness to be drilled), the more the conical shape is reduced. The reduction in the tapered shape does not make it possible to precisely control the various levels of gray in the final watermark observed in transmitted light. The use of a laser to produce the perforations does not therefore make it possible to precisely control the diameter of the perforation as a function of the height of the relief. This results in a loss of definition during the formation of the watermark.
    There is a need to obtain a watermark having a better definition, a high contrast and pronounced lights, especially to increase the security of watermarked substrates and render their authentication or their easier identification. The applicant therefore proposes to solve the problems of the state of the art by proposing a multi-tone watermark according to the invention.
    A subject of the invention is a sheet, in particular a protective sheet comprising a multi-tone watermark having high definition, high contrast and pronounced lights. Another subject of the invention is such a multi-tone watermark.
    This multi-tone watermark has a high level of detail, and in particular strong shadows with a standard deviation of the distribution of the 8-bit coded gray levels of more than 10, preferably more than 15, and / or an 8-bit encoded gray level deviation of more than 120, preferably greater than 150. Gray level distribution is obtained by acquiring the image of that multi-tone watermark using a scanner in mode 600 dpi transmission. The acquisition is carried out in particular in the transparency mode (therefore in the transmission mode) with a flatbed scanner and while taking the following precautions: - calorimetric calibration according to the scanner's ICM ("Image Color Management") standard and the acquisition chain, - optionally, the limitation of the illumination by polarization filter to avoid any reflections and any saturation, and - acquisition with all corrections disabled to obtain a raw signal with no retouching.
    In particular, it is possible to use the EPSON® Perfection V750 Pro scanner to perform this acquisition.
    The limitation of illumination by a polarization filter can be carried out by applying a filter to the scanner acquisition area, in particular the scanner glass.
    In particular, said multi-tone watermark comprises regions of pronounced light, in particular which are characterized by a "maximum gray level" - difference from "average gray level" of more than 50, preferably more than 100, and / or an 8-bit coded gray level deviation of more than 120, preferably more than 150. Thus, the multi-tone watermark has very pronounced lights obtained without adding a specific piece additional.
    The multi-tone watermark according to the invention is preferably formed using a single piece, in particular attached to the drainage fabric.
    The shadows and the various gray levels of the watermark are obtained by the relief and perforations of the piece used for the formation of the watermark.
    The multi-tone watermark obtained comprises at least three different thickness values.
    This watermark also has a very good look-through (appearance of the paper when seen against the light, revealing the texture and formation of the leaf), that is, an even distribution of the fibers and no or few clusters of fibers (also known as "flakes"). The look-through is a measure of the leaf formation observed in transmitted light, it is, for example, measured by a 2D leaf formation sensor, in particular developed by the company TECHPAP.
    In particular, the look-through of the watermark measured in a "full tone" is better than the look-through of the tissue paper of the sheet containing that watermark because the formation of the watermark occurs in a piece that it is provided with a relief and that is perforated and not on a drainage fabric that has a less uniform surface between the threads of said drainage fabric. In this way, watermarks of multiple shades formed using a fur that is provided with a relief that is perforated have a better definition than the watermarks obtained by virtue of an embossing of the drainage fabric.
    In particular, this watermark comprises a code formed, in positive or negative, by a network of dark spots.
    This code can be an image, an alphanumeric character, an ideogram, a symbol, a word or even initials.
    Said code may be able to be observed in light transmitted to the naked eye, that is, without a device that makes it possible to increase the watermark, or also using a device that makes it possible to increase the watermark, for example in order to magnify glass , an image acquisition device, especially a transmission mode scanner or a microscope.
    Said code is in particular an element of authentication of the watermark and more broadly of the substrate comprising it. In particular, said code can be a serial number corresponding to a banknote paper manufacture.
    The invention also relates to a document comprising or consisting of a sheet according to the invention. Such a document is chosen in particular from property titles, cards, certificates, diplomas, bank notes, passports, identity cards, driving licenses, checks, tickets to enter cultural or sporting events or letterhead.
    The invention extends to a method for manufacturing a piece of a multi-tone watermark on a substrate by draining a fibrous suspension, said piece comprising a relief on one of its faces referred to as the "profiled face" and opposite to the "drainage face", and perforations, said perforations comprising a passage channel with an entrance on the profiled face and an exit on the drainage face, comprising the steps consisting in the formation of said relief and forming said perforations in said piece so that each perforation is such that the sectional cut area of its channel at a given distance from the drainage face depends directly on that distance.
    The expression "depend directly" is understood here as the meaning that the sectional sectional area of a drilling channel at a given distance from the drainage face is a function, in particular proportional, preferably linearly, at that distance. In particular, for a part comprising a substantially flat drain face, there is a proportionality link between the sectional cut area of the hole channel at a given distance from the drain face and that given distance. Thus, the drainage capacity of a perforation depends on the relative position of the relief with respect to that perforation.
    Preferably, the linear variation is opposite, in other words, the greater the distance, the smaller the sectional sectional area of a drilling channel. In other words, the sectional cut area of a drilling channel decreases from the drain face to the profiled face.
    The part may comprise perforations that all have the same section cut for a given distance from the drain face.
    The thickness of the part can be variable, so that the thickness of the perforations can be variable. The perforations can all be through perforations, that is, they emerge on the profiled face. As a variation, at least a portion of the perforations, or even all perforations, can be blind perforations, that is, the perforations do not reach the profiled face. The part can have, in particular, a chosen thickness so that the perforations cannot emerge on the profiled face.
    Most perforations, or rather, all perforations, may have a sectional cut variation as a function of the distance to the drain face.
    During the creation of a part according to the invention, the effect of drainage on the formation of the watermark can be predicted. It is, therefore, possible to predict the effects of the relief and those of perforations in the formation of a watermark and, consequently, determine the relief and perforations of a piece to obtain a given watermark.
    Said "drain face" is preferably substantially flat. As a variation, it follows the relief of the drainage tissue.
    According to a particular case of the invention, said piece is metallic or ceramic.
    The term "metallic part" is understood in particular to mean a part comprising steel, nickel, copper, stainless steel, titanium, tungsten, cobalt, brass and / or alloys thereof, for example stainless steel.
    According to a particular case of the invention, said method comprises at least one sintering step to which said part is subjected.
    According to a particular case of the invention, the relief of the "profiled" face and the perforations are formed during the manufacture of said piece, especially during the same stage and in particular simultaneously. This makes it possible, in particular, not to weaken the part by subsequent drilling operations and to save time during the manufacture of said part by reducing the number of steps required.
    In particular, the manufacture of said part is thus carried out without repetition of the surface application or drilling. These operations contribute specifically to increase the cost of the piece and are detrimental to the possibility of reproducing the method. However, this method makes it possible to obtain identical parts.
    According to a variation of the invention, said method for manufacturing a part for forming a watermark on a substrate by draining a fibrous suspension, is characterized by the fact that said part is injection molded, referred to as molding by injection making it possible to obtain said relief and said perforations simultaneously.
    In particular, said manufacturing method is a method that comprises at least the following steps: - using a metallic powder or a ceramic powder, and optionally a thermoplastic binder, - injecting said powder, and where appropriate said binder, into a mold allowing formation of a part comprising said relief and said perforations, - optionally disconnect said part, and - sinter the part, that is, perform the solid state densification thereof.
    Such a method is a method for molding metals or ceramics by injection (MIM for "Metal Injection Molding" or CIM for "Ceramic Injection Molding" method) which makes it possible in particular to produce complex shapes on mechanically strong parts with very high precision and high efficiency, without requiring subsequent machining. In addition, this technology makes it possible to produce visual pieces with inadequate shapes that are difficult to machine and with very high surface qualities.
    Said metallic powder can be chosen from powders of iron, nickel, copper, stainless steel, titanium, tungsten, cobalt and alloys thereof, for example, stainless steel. It can be a particulate powder, the largest dimension of which is less than 50 pm, preferably between 1 and 40 pm. Preferably, said metallic powder is a powder of copper alloy, iron alloy, tin alloy, or an alloy of stainless metals such as nickel and chromium, or of pure metal such as titanium. Copper alloys and stainless metal alloys have the advantage of withstanding corrosion during paper production.
    Said ceramic powder may comprise especially zirconia.
    Said thermoplastic binder can be chosen from polyethylene (PE), polypropylene (PP), paraffin, stearic acid, polyacetal (POM) and mixtures thereof. Preferably, said thermoplastic binder is polyacetal (POM).
    Said mixture may comprise in particular 60% metallic powder and 40% plastic binder.
    Mixtures of ceramic powder and thermoplastic binder are commercially available. It may be especially the Catamold® product sold by BASF. Said advertised mixtures can be in the form of metallic powder or mixed metallic powder granules mixed or coated with a thermoplastic binder. Said granules are ready for use by injection into a mold.
    Said mold comprises an upper face and a lower face. Once the mold is closed, the interior of the upper face is provided with a relief and the lower and upper faces are connected by several "columns" that are used to form the perforations of the said piece. Said columns may have a rounded or polygonal cross section, said cross section having an area that decreases when going from said lower face to said upper face. The shape of the mold is substantially complementary to the shape of the said piece for the formation of a watermark, with differences possible in particular due to the process used.
    Considering that machining only makes it possible to produce conical or cylindrical perforations in the material and considering that a laser does not allow the control of the shape of the perforations made, the process of molding metals by injection makes it possible to produce perforations having a polygonal cross section that has a behavior, with respect to drainage of the fibrous suspension during the formation of the watermark, similar to that of the perforations having a rounded cross section, for example with a polygon comprising at least six, preferably at least 10 sides, while allowing a better stiffening of the mold, the columns having a polygonal cross section being less subject to torsion and bending phenomena.
    Once the part is demoulded, the purpose of the shutdown operation is to remove the thermoplastic binder. This operation can be carried out using a solvent (in particular removal by chemical reaction or dissolution) and / or cooking (in particular removal by evaporation or destruction of chemical bonds by catalysis), whose atmospheric, temperature and pressure conditions may vary depending on the mixture used.
    The sintering operation performed on the disconnected part is a heat treatment allowing the densification of the solid state of the material. It can be carried out under a reduced atmosphere or under vacuum and at temperatures that are high, but which are below the melting point of the metal used, for example above 1200 ° C for certain iron alloys and stainless metals. The sintering is accompanied by a phenomenon of dimensional shrinkage of the part, the metal densifies occupying the free spaces left by the thermoplastic binder removed during the shutdown operation. This dimensional shrinkage is controlled by the operating conditions and, in addition, occurs with conservation of volume and reliefs. This piece consequently reaches a density close to 1, for example greater than 0.98, and is an exact replica (tolerances are very low, in the range of 0.03 to 0.07%) on a scale of less than than 1, for example on a scale of 80%, from the inside of the mold (top face relief and perforations formed by the included columns).
    As long as the sintering operation is under control over time, temperature and pressure parameters, the density can be controlled and adapted to the alloys used. For example, it will be very close to 1 with titanium based powders and between 0.8 and 1 for copper alloys.
    Consequently, a density of 0.8 results in the production of a porous part. This controlled residual porosity during production gives the part filtering properties.
    Optimal operating conditions, in particular the atmosphere, temperature and pressure, can be determined by a person skilled in the art.
    The invention also extends to a mold as previously described and intended to be used for the manufacture of a part to form a multi-tone watermark according to the invention, in particular by a process for molding metals and ceramics by injection.
    According to another variation of the invention, said method for manufacturing a part to form a watermark comprises at least the steps of using a powder and densifying said powder, in particular metallic powder, under the action of a laser. .
    In particular, this method for manufacturing a part for forming a multi-tone watermark on a substrate by draining a fibrous suspension is a method of sintering using a laser. In particular it is a selective laser fusion method (SLM) or a selective laser sintering method (SLS). Said sintering method using a laser makes it possible to form said relief and said perforations during one and the same stage. The SLM method allows the local densification of a material in the form of powder, fusing it under the action of a high-energy laser. The powder material is, for example, a metallic powder. The operating conditions for such a method may be as follows: - manufacturing chamber under a nitrogen atmosphere, - use of an infrared (IR) laser having, for example, an energy between 50 and 100 watts, and - use of metals such as such as stainless steels or tool steels, titanium, chromium-cobalt mixtures or even aluminum. - SLM method makes it possible to achieve an accuracy of ± 50 pm for 100 mm, that is, 0.05%.
    Due to the precision and low tolerances of the methods described above, especially MIM, CIM or SLM, identical parts are obtained using the same mold and consequently a very high reproducibility of the multi-tone watermarks formed using these parts is obtained. This precision and these low tolerances also make it possible to obtain parts with a relief having an accuracy between 0.03 and 0.07% and very fine perforations that can reach 0.2 mm in diameter. The watermarks formed using these pieces, therefore, have a better resolution and also a greater fineness and greater precision, particularly in terms of the details of the pattern such as the hair in a portrait or the characteristics of a face, which are even greater than those obtained by virtue of the previous methods.
    The invention also relates to a piece to form a watermark, as described above, on a substrate by draining a fibrous suspension, characterized by the fact that it comprises a relief on one of its faces referred to as the "profiled face" and opposite to the "drain face", and perforations, said perforations comprising a through channel with an entrance on the profiled face and an exit from the drain face, and each perforation being so that the sectional cut area of its channel in one given distance from the drain face depends directly on that distance.
    In particular, the drain face is substantially flat, and is preferably flat.
    According to a particular case of the invention, the cross-section of said perforations is oval, preferably a disc.
    According to a particular case of the invention, said perforations have a polygonal cross section, the area of which decreases when going from the drainage face towards the profiled face. Consequently, the drainage capacity is proportional to the length of the channel, that is, the relief, so that the more the relief is on the drainage face, the lower the drainage capacity. This proportionality link makes it possible to considerably facilitate the design of the relief. Consequently, it is an easier effect to predict the effects of perforations on the deposition of fibers in said part during drainage and, therefore, to predict the pattern that will appear during observation in the transmitted light of the watermark formed using that part.
    In addition, the increased regions of the relief correspond to the regions where the deposition of the fibers will be lower, both due to the relief, as explained above, and due to the fact that the sectional cut area of the perforation channel located in this increased region of the relief is reduced. Its drainage capacities are in effect smaller than those of the perforations located in the less enlarged regions. This, in particular, has the effect of lesser suction and consequently lesser deposition of fibers in said increased regions. For these regions, very pronounced lights are obtained, similar to those obtained with galvanies, but which is impossible to obtain by simply embossing the drainage tissue.
    The perforations are preferably thin enough not to pass through the fibers of the fibrous suspension during drainage.
    According to a particular case of the invention, the perforations are evenly distributed. They form, for example, rows and columns respectively 0.3 to 0.6 mm apart. As a variation, the perforations are distributed in a variable manner.
    According to a particular case of the invention, the shape, dimensions, distribution and / or position of the perforations form, in positive or negative, a code, in particular an image, an alphanumeric sign, an ideogram, a symbol, a word or even initials.
    Said code is, therefore, an authentication element of said piece, but also of a sheet comprising a multi-tone watermark obtained using said piece. In fact, perforations can be seen in the watermark in the form of obscure spots.
    According to the size of the perforations, the position of the perforations and consequently that code may be able to be observed in light transmitted to the naked eye, that is, without a device that makes it possible to increase the watermark or even with the aid of a device that makes it possible to increase the watermark, for example in order to magnify glass, a counter, an image acquisition device, in particular a scanner in the transmission mode or a microscope.
    Said code may constitute an authentication or identification element of the manufacturer of said piece for the formation of a multi-tone watermark, of the substrate manufacturer comprising said multi-tone watermark, of the customer or of the ordering part. Such code is not removable and difficult to falsify, in particular, more difficult to falsify than an impression.
    According to a variation of the invention, said piece is uniformly perforated over its entire surface, in particular along lines and columns, for example that are evenly spaced, and at least one perforation is not a through perforation. In other words, the relief is locally higher, that is, at a greater distance from the drainage face than the perforations. In this way, more pronounced lights are obtained than previously, the suction being zero at the level of said at least one blind perforation. In addition, during drainage, the perforations located around said at least one blind perforation attract, by suction, the fibers located above said at least one blind perforation. This has the effect of creating even more pronounced lights, and in particular lights that are more pronounced than in the case of a non-perforated part or a part that is uniformly perforated, but has no blind perforations.
    In a particular case of the invention, certain regions of said part for forming a watermark are devoid of perforations. The drainage is, consequently, locally reduced and lighter regions of the watermark are obtained that contrast (in particular in constant relief) with the neighboring regions provided with perforations. The method according to the invention also makes it possible to create very pronounced reliefs and in particular lower regions positioned on the profiled face in the vicinity of the high regions. This, combined with the suction of the perforations, makes it possible to obtain contrasted and highly shaded watermarks that have, in particular, pronounced lights close to the darkness.
    The invention extends to the use of at least one piece to form a multi-tone watermark on a substrate by draining a fibrous suspension, said piece comprising a relief on one of its faces referred to as the "profiled face" and opposite to the "drain face", and perforations comprising a through channel with an entrance on the profiled face and an exit on the drain face, the sectional sectional area of the channel of each drilling at a given distance from the drain face depends directly on that distance. According to this use, at least one piece is attached to or on the drainage fabric through which a fibrous suspension is drained.
    In particular, said piece is metallic or ceramic.
    The term "drainage tissue" is understood to mean a surface comprising openings suitable for drainage during papermaking. Such drainage fabric preferably comprises several overlapping fabrics and in particular a support fabric comprising large openings positioned over which are woven fabrics comprising smaller openings. Said drainage fabric and said overlapping fabrics can be woven, electroformed or consist of a perforated plate.
    A drainage fabric equipped with metal parts according to the invention is less vulnerable than conventional embossed drainage fabrics, in particular with regard to mechanical shocks.
    Said piece can, in particular, be fixed to the forming fabric by welding, by adhesive bonding, by pressing or by attachment.
    Preferably, said drainage fabric or at least one of said overlapping fabrics is a metallic fabric. The use of metal parts makes it possible to easily fix said parts, in particular by welding.
    Drainage of the fibrous suspension can take place by means of a fourdrinier or a cylindrical mold.
    According to a particular case of the invention, the drainage fabric, and in particular at least one of said overlapping fabrics, can be cut or embossed to allow fixing of said piece.
    The position of said piece, in particular the distance of said piece to the plane of the drainage fabric that comprises it, can be chosen in order to obtain the desired average value of the thickness (therefore, opacity) of the watermark. Consequently, the smaller the part is, the higher the average thickness value in relation to that part.
    In particular, the part can be placed vertically so that the profiled face, in particular the higher portions, of that referred to coincides with the plane of the drainage fabric. The piece can, for example, protrude by less than 2 mm, preferably less than 1 mm, from the drainage fabric. In this way, the part is protected from possible mechanical damage during the formation of the watermark. In addition, due to the stiffness of the part, its ability to withstand a mechanical load on or in the drainage fabric will be greater than for the watermark region (or embossed region) of a conventional drainage fabric. The part can also be positioned below the plane of the drain fabric.
    According to a particular case of the invention, the drainage fabric can also comprise regions that allow the formation of watermarks according to the state of the art. These regions allowing the formation of watermarks according to the state of the art can, for example, correspond to the watermarks comprising the reliefs that are obtained by embossing the drainage fabric or the "selected watermarks. "comprising two levels of gray as described in application EP 1 122 360. In particular, the regions allowing the formation of watermarks according to the state of the art and according to the invention are positioned in the drainage fabrics of so that the watermarks are juxtaposed or overlapping. They are preferably complementary and can form one or the same pattern. The protection of the leaf comprising the watermarks is improved because the method for forming the watermarks uses different technologies.
    The invention will be better understood from reading the following non-limiting examples and figures. EXAMPLE
    A unique impression mold, whose shape is complementary to the shape of the desired piece, is produced which comprises a relief on one of its internal faces referred to as the upper face and columns. Said columns go from the opposite face to the upper face, referred to as a lower face, towards the upper face that they may or may not reach, depending on the case said columns will, therefore, be used for the formation, respectively, of the conical passage perforations. or blind perforations. The sectional sectional area of each column at a given distance from the bottom face varies with that distance linearly and in the opposite direction, in other words the greater the distance, the smaller the cross-sectional area of that column.
    Granules from Catamold® resins sold by BASF are introduced at a conventional injection pressure. These granules, constituted of metallic powder with thermoplastic binder, are then heated and injected in the mold described above to obtain a first part.
    That piece is then turned off by cooking in an oven. The thermoplastic binder is consequently removed.
    The disconnected part is then sintered by cooking in an oven. This solid state densification of the material (temperature below the melting point of the metal) by means of heat gives the piece its final cohesion and final density, and is accompanied by a controlled shrinkage, but a conservation of volume. In this way, the part is then obtained. P2 is an exact replica on a smaller scale of the shape of the mold and the part before sintering.
    Then, the image of two 3 cm x 3 cm watermarks representing one and the same portrait is acquired by a scanner in the 600 dpi transmission mode. The lighting and purchase conditions are identical for the two watermarks. The first F1 watermark was produced using an embossing of the fabric forming a certain relief. The second watermark F2 was produced using the part P2 according to the invention, the manufacture of which was described above. Said part P2 comprises in its profiled face a
    relief identical to that formed by embossing the fabric used for the first F1 watermark.
    The two watermarks F1 and F2 consequently obtained are easily distinguishable by observing the light transmitted to the naked eye, the F2 image has, in particular, a better definition, a better contrast, more pronounced lights, a better precision of the pattern and a better look-through.
    The images are then obtained in 8-bit coded gray levels from 0 for black to 255 for white.
    Gray level measurements are made for each watermark in two regions of the portrait: the face and the hair. Measurements are, for example, performed using the EPSON® Perfection V750 Pro scanner, in particular, according to the protocol described above.
    A gray level distribution curve is then established for each watermark, counting for each of these regions, the number of pixels corresponding to each gray level. These curves make it possible to obtain the data collected in the following table:

    Table 1: 8-bit coded gray levels.
    The watermark F2 according to the invention has a medium gray level higher than the average gray level of F1. In its entirety, it is therefore clearer than the F1 watermark.
    The watermark F2 has a standard deviation from the gray levels greater than that of the watermark F1, so it is more contrasted than the watermark F1.
    The watermark F2 has a deviation from the gray levels greater than the deviation from the gray levels of the watermark F1, respectively for the same regions. These regions are, therefore, more contrasted in the watermark F2 than in the watermark F1.
    The F2 watermark has a higher gray level than the F1 watermark, the lights are therefore more pronounced over the F2 watermark. DESCRIPTION OF THE FIGURES
    Figure 1 represents a galvanic for watermark formation according to the state of the art.
    Figure 2 represents the embossing of a fabric for the formation of a watermark according to the state of the art.
    Figure 3 represents a piece that allows the production of a watermark according to the invention.
    Figure 4 illustrates the correspondence between the relief of the part used and the watermark obtained.
    Figure 5 represents a negative code formed by the perforations.
    Figure 6 represents a piece according to the invention in a forming fabric.
    According to the state of the art described above and which allows the formation of watermarks having a single gray shade, a galvanic 1 as shown in figure 1 and attached to the fabric forming a paper machine.
    In addition, as previously described, it is known to emboss the fabric forming a paper making machine to produce multi-tone watermarks. Figure 2 represents a fabric 2 comprising an embossed region 3 allowing the formation of a multi-tone watermark. The region 31 being larger than the rest of the fabric, this allows the formation of a clear watermark region. Conversely, region 32 allows the formation of an obscure watermark region. As long as regions 31 and 32 comprise a multilevel relief, they make it possible to obtain a multi-tone watermark.
    A part 4 according to the invention for forming a multi-tone watermark is shown schematically in figure 3. Said part 4 comprises a face 5 provided with a relief and conical perforations 6, and the drainage capacity of each perforation. 6 depends directly on the distance to the drainage face of the cross section on the profiled face of the channel formed by the said perforation 6.
    Due to the relief of face 5, perforations 61 are not through perforations. This has, in particular, the effect of allowing the formation of very clear watermark regions.
    By way of observation, depending on the method used to manufacture said part 4 for the formation of a watermark, and in particular for the manufacture of the mold that makes it possible to obtain said part 4, it may be easier and more practical to manufacture said mold with a lower face comprising columns uniformly distributed and with a relief on its upper face which may, locally, be larger than said columns in order to form blind perforations on the part 4. The manufacture of a mold with regions comprising columns uniformly distributed and other regions devoid of columns, may in fact prove more complex depending on the method used.
    Figure 4 illustrates the correspondence between a piece 4 according to the invention to form a watermark and the shades of gray obtained from said multi-tone watermark. Said part 4 comprises a surface 5 provided with a relief and perforations 6, certain that 61 are not through perforations. The part 4 shown in figure 5 makes it possible to obtain a multi-tone watermark 8 according to the invention comprising various levels of gray.
    Regions 71 and 73 have a lower relief and, consequently, perforations that have a high drainage capacity, they therefore correspond to the dark ones of the watermark 8. Region 72 has a higher relief than that of regions 71 and 73 , this corresponds, therefore, to a region ranging from light to very light (from left to right) of the watermark 8. Region 74 has a high relief and a blind perforation 61 and corresponds to a very light region the watermark. The method according to the invention that is used to manufacture part 4, due to its precision, makes it possible to obtain "abrupt" reliefs that are expressed in the watermark by the presence of very clear regions, such as region 74, directly adjacent to very obscure regions, such as region 73. In the same way as above, region 76 corresponds to a clarity of the watermark placed between two obscurations corresponding to regions 75 and 77. Regions 71.75 and 77 allow the formation of very obscure regions in the watermark 8 because in addition to the hole formed by the relief of face 5, the perforations are greater in these regions and therefore the drainage is greater. This results in greater densification of the fibrous groove being formed and consequently the formation of obscure regions.
    The position and distribution of the perforations 6 on the surface of the "profiled" face 5 of the part 4 according to the invention makes it possible to form a code 62. Figure 5 is a top view of such part 4. This reveals the code 62 "AW" negative. This code can be produced by means of blind perforations 61 positioned according to code 62 or by the fact that part 4 has no perforations in the region forming code 62.
    According to a variation that is not represented, code 62 can be formed by perforations that each have a cross section on the "profiled" face 5 of the Ai area considering the outside of the region defined by code 62, the "profiled face. "5 is provided with perforations that each have a cross section of area A2 greater than Ai. The proportional ratio between Ai and A2 is chosen in particular to make it visible, for example, under observation in light transmitted with a magnifying glass with 5x enlargement, referred to as code 62.
    A part 4 according to the invention is shown in figure 6. It can be welded in particular by means of a weld 9 for an embossed region 21 of the drainage fabric 2. This part 4 comprises a "profiled" face 5, perforations 6 and blind perforations 61.
    The expression "having one" or "comprising one" should be understood as being synonymous with "having at least one" or "comprising at least one", unless otherwise specified.
    权利要求:
    Claims (14)
    [0001]
    1. Sheet of paper, in particular a protective sheet, comprising at least one multi-tone watermark (8) characterized by the fact that the standard deviation of the distribution of the 8-bit coded gray levels is greater than 10.
    [0002]
    2. Leaf, according to claim 1, characterized by the fact that the watermark (8) comprises a code (62), in particular an image, an alphanumeric sign, an ideogram, a symbol, a word or perhaps initials, formed by a network of dark spots.
    [0003]
    3. Document, characterized by the fact that it comprises a sheet as defined in any of claims 1 or 2, said document being, in particular, chosen from property titles, certificates, diplomas, ballots, passports, identity cards, licenses for driving, checks, tickets to enter cultural or sporting events or letterhead.
    [0004]
    4. Method for manufacturing a piece (4) to form a multi-tone watermark (8) on a substrate by draining a fibrous suspension, said piece (4) comprising a relief on one of its faces (5) referred to as the "profiled face" and opposite to the "drainage face", and perforations (6), said perforations (6) comprising a passage channel with an inlet on the profiled face (5) and an outlet on the drainage face, referred to part (4) being subjected to at least one sintering step, said method characterized by the fact that it comprises the steps consisting of the formation of said relief and formation of said perforations (6) in said part (4) so that each perforation ( 6) it is such that the sectional cut area of its channel at a given distance from the drainage face depends directly on the said distance, the relief of the profiled face (5) and the perforations (6) being produced simultaneously, the referred piece (4) being remarkably metallic or ceramic.
    [0005]
    5. Method of manufacture, according to claim 4, characterized by the fact that it comprises at least the steps consisting of the use of a powder and densification of said powder, in particular metallic powder, under the action of a laser.
    [0006]
    Method of manufacture according to any one of claims 4 to 5, characterized in that the at least one sintering step is a laser sintering step, in particular a selective laser fusion method (SLM) or a selective laser sintering method, best of the SLM type.
    [0007]
    7. Manufacturing method according to claim 4, characterized by the fact that it comprises at least the following steps: - using a metallic powder or a ceramic powder, and optionally a thermoplastic binder, - injecting said powder and, where appropriate , said binder, in a mold allowing the formation of a part (4) comprising said relief and said perforations (6), - optionally peeling off said part (4) consequently obtained, and - sintering the peeled part (4).
    [0008]
    8. Method of manufacturing a piece (4) to form a multi-tone watermark (8) on a substrate by draining a fibrous suspension, said piece (4) comprising a relief on one of its faces (5) referred to as the "profiled face" and opposite to the "drainage face", and perforations (6), said perforations (6) comprising a passage channel with an inlet on the profiled face (5) and an outlet on the drainage face, referred to part (4) being injection molded, said method characterized by the fact that it comprises the steps consisting of the formation of said relief and formation of said perforations (6) in said part (4) so that each perforation (6) is such that the sectional cut area of its channel at a given distance from the drainage face depends directly on the said distance, said injection molding allowing to obtain said relief and said perforations simultaneously, said piece (4) being remarkably metallic or ceramic here.
    [0009]
    9. Part (4) manufactured using the method as defined in any of claims 4 to 8, to form a multi-tone watermark (8) on a substrate by draining a fibrous suspension, comprising a relief in a of its faces (5) referred to as the "profiled face" and opposite to the "drainage face", and perforations (6), referred to perforations (6) comprising a passage channel with an entrance over the profiled face (5) and a exit on the drainage face, characterized by the fact that each perforation (6) being such that the sectional cut area of its channel at a given distance from the drainage face depends directly on the said distance, the said piece (4) being remarkably metallic or ceramic.
    [0010]
    10. Piece (4), according to claim 9, characterized by the fact that the dimensions, distribution and / or position of said perforations form a code (62), in particular an image, an alphanumeric sign, an ideogram , a symbol, a word or even initials.
    [0011]
    11. Part (4) according to any one of claims 9 to 10, characterized in that the cross-sectional area of a perforation channel (6) decreases from the drainage face to the profiled face, most perforations (6) having a remarkably identical cross-sectional variation as a function of the distance to the drainage face.
    [0012]
    12. Part (4) according to any one of claims 9 to 11, characterized by the fact that it comprises perforations (6), all having the same cross section at a given distance from the drainage face.
    [0013]
    13. Part (4) according to any one of claims 9 to 12, characterized in that it comprises through perforations (6) and blind perforations.
    [0014]
    14. Use of at least one part (4) as defined in any of claims 9 to 13, to form a multi-tone watermark (8) on a substrate by draining a fibrous suspension, referred to at least one part (4) characterized by the fact that it is fixed on or on a drainage tissue through which a fibrous suspension is drained.
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    同族专利:
    公开号 | 公开日
    FR2957943B1|2021-11-05|
    PL2550395T3|2018-04-30|
    US8840756B2|2014-09-23|
    CN102971461A|2013-03-13|
    WO2011117828A1|2011-09-29|
    EP2550395B1|2017-10-25|
    FR2957943A1|2011-09-30|
    HUE036175T2|2018-06-28|
    RU2567357C2|2015-11-10|
    CN102971461B|2015-10-14|
    ES2655987T3|2018-02-22|
    RU2012144579A|2014-04-27|
    EP2550395A1|2013-01-30|
    SI2550395T1|2018-02-28|
    BR112012023906A2|2016-08-02|
    US20130255896A1|2013-10-03|
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    GB2533264A|2014-11-10|2016-06-22|De La Rue Int Ltd|Improvements in watermarking|
    CN104562824A|2015-01-04|2015-04-29|昆山钞票纸业有限公司|White watermark mould plate, white watermark cylinder mould and prepared anti-counterfeit paper|
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    FR3034110B1|2015-03-23|2017-04-21|Arjowiggins Security|PAPER COMPRISING SYNTHETIC FIBERS|
    FR3059682B1|2016-12-02|2020-10-30|Arjowiggins Security|METHOD FOR MANUFACTURING A WATERMARK PAPER|
    CN110603360B|2017-02-27|2022-02-18|克瑞尼股份有限公司|Paper comprising a multi-tone watermark and watermarking tool for making such paper|
    CN110869555B|2017-08-17|2021-12-07|保定钞票纸业有限公司|Paper preparation method capable of controlling watermark brightness and paper product|
    BR112019026081A2|2017-09-11|2020-06-30|Crane & Co., Inc.|brand sheet d? water, apparatus, and document, and methods for providing the same|
    CN109385932A|2018-11-23|2019-02-26|长沙云聚汇科技有限公司|A kind of device preparing the non-woven fabrics automobile interior decoration with 3D sense of touch|
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    法律状态:
    2018-04-10| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-02-19| B06T| Formal requirements before examination [chapter 6.20 patent gazette]|
    2020-01-14| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|
    2020-07-07| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2020-09-29| B25A| Requested transfer of rights approved|Owner name: OBERTHUR FIDUCIAIRE SAS (FR) |
    2020-10-13| B25A| Requested transfer of rights approved|Owner name: OBERTHUR FIDUCIAIRE SAS (FR) |
    2020-11-10| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 23/03/2011, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1001164|2010-03-24|
    FR1001164A|FR2957943B1|2010-03-24|2010-03-24|WATERMARK, METHODS FOR MANUFACTURING A PART FOR THE FORMATION OF A WATERMARK AND PART OBTAINED ACCORDING TO THIS PROCEDURE|
    PCT/IB2011/051226|WO2011117828A1|2010-03-24|2011-03-23|Sheet having multitone watermark, method for manufacturing part for forming multitone watermark, part for forming multitone watermark, and use of said part for forming multitone watermark|
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