EP2198086B1 - Sheet having at least one watermark or pseudo-watermark observable only on one side of the sheet - Google Patents

Description

The present invention relates to a sheet comprising at least one watermark or pseudo-watermark and also relates to an article, in particular a security document, comprising said sheet.

To guard against counterfeiting or falsification of security documents such as means of payment such as banknotes, checks, or official documents including identification documents such as passports, identity cards, or tickets entry to cultural events or sports tickets or transport tickets, one can use various security means such as watermarks, which allow to authenticate a document observation transmitted light. In addition, these watermarks protect from copying by optical means such as photocopying, photography or digitization, the copy medium having no embedded watermark.

Watermarks are also used for decorative purposes and prestige especially for printing-writing papers, especially for letterheads, or art papers such as watercolor papers.

The watermarks in the paper sheets are conventionally obtained during the manufacture of the wet-phase sheet by the deposition of the paper pulp on the embossed web of the paper machine, the amount of pulp deposited is higher in the hollows of the paper machine. embossing and less in the bumps compared to the rest of the paper, which creates differences in opacity, the denser dough areas appear darker and the less dense areas appear lighter, compared to the rest of the sheet (said part vellum) when viewing the leaf (after drying) in transmitted light. This technique relates to the manufacture of a paper on a paper machine with round shape. These watermarks have different levels of gray depending on the relief of the embossings and are called multitone watermarks.

The watermarks can also be made by embossing a wet sheet with a watermarking roll (also called "dandy roll") on a flat-bed paper machine.

Also known is a technique for making paper with watermarks having a multiton effect, described in the patent application. EP-A-1122360 , by creating lighter areas (of lower surface density than the vellum zone of the sheet) arranged to form a halftone image in the sheet, obtained with the aid of a set of masks fixed on the drip sheet of the paper machine.

In the patent application FR 0650470 , a sheet material having at least one first layer defining an outer face of said material and having at least one first color, and at least one second layer having at least one watermark and having at least one second color, the first and second layer having at least different saturations and / or angles of hues. Colored and visible watermarks are thus obtained through the material.

WO 2004/076198 discloses a multilayer structure having two layers of paper on either side of a plastic layer, the cohesion between the layers of paper and the plastic layer being ensured by penetration of regions of the plastic layer in the paper layers. At least one of the layers of paper may have one or more watermarks.
US 2007/0058260 describes lens arrays having different lens shapes and densities superimposed on micro-images to form a material for observing an image that can exhibit different optical effects.

It is also known to make pseudo-watermarks on a sheet of paper. Pseudo-watermarks reproduce the appearance of a watermark with differences in opacity. These pseudo-watermarks can be obtained mechanically by supplying pressure with or without heat input and / or chemically by applying a composition, for example by increasing the transparency of the paper locally by means of transparentizing substances. The density of fibrous material between the lightest and darkest areas of the pseudo-watermark may be uniform unlike a conventional watermark.

There is a need to provide new security against falsification for sheets and security documents, which are easily observable by the man in the street while having a sufficient level of security.

There is also a need for filigree or pseudo-watermarked papers in the field of fine papers or art and / or print-writing having a new aesthetic effect also contributing, if necessary, to the authentication of paper .

The present invention proposes, in order to meet the needs stated above, a sheet comprising a front face and a back face and at least one watermark or pseudo-watermark, this sheet being such that said watermark or pseudo-watermark is observable in transmitted light, less than one of the faces of said sheet.

• une première couche comportant au moins un premier filigrane ou pseudo-filigrane,
• une seconde couche comportant au moins un second filigrane ou pseudo-filigrane, cette feuille étant telle que ledit premier filigrane ou pseudo-filigrane ne soit observable en lumière transmise, au moins en partie, que de la face recto de la feuille et que ledit second filigrane ou pseudo-filigrane ne soit observable en lumière transmise, au moins en partie, que de la face verso de la feuille.

The invention more particularly relates to a sheet comprising a front face and a reverse side comprising:

• a first layer comprising at least a first watermark or pseudo-watermark,
• a second layer comprising at least one second watermark or pseudo-watermark, this sheet being such that said first watermark or pseudo-watermark is observable in light transmitted, at least in part, only from the front face of the sheet and that said second watermark or pseudo-watermark is observable in transmitted light, at least in part, only from the reverse side of the sheet.

Each of these watermarks or pseudo-watermarks is therefore observable in transmitted light, at least in part, when we look respectively at the layer having it. These watermarks or pseudo-watermarks are not clearly observable, at least in part, simultaneously in transmitted light on the same side of the sheet.

The sheet according to the invention comprises at least one interlayer translucent and diffusing light called "diffusing layer", located between the first and second layers. By "translucent" is meant that the material of the layer passes enough light to see through the layer.

The interlayer is such that the first watermark or pseudo-watermark is observable in light transmitted, at least in part, only from the front face of the sheet at the interlayer and the second watermark or pseudo-watermark is not observable in transmitted light, at least in part, than the back side of the sheet at the intermediate layer.

Thanks to the invention, it is possible to prevent a combination of watermarks or pseudo-watermarks of the two layers together, in particular by the presence of the interlayer. Indeed, without the presence of the interlayer at the level of watermarks or pseudo-watermarks, a combination of watermarks or pseudo-watermarks would be possible.

The watermarks or pseudo-watermarks of the two layers may be at least partially superimposed on one another, especially at the level of the interlayer. In particular, the watermarks or pseudo-watermarks can be totally superimposed on one another. Alternatively, the watermarks or pseudo-watermarks may not be superimposed on each other, being for example disjoint or contiguous.

Watermark or pseudo-watermark

The term "watermark or pseudo-watermark" according to the invention, a drawn image which appears in the thickness of the sheet, in particular in the thickness of the first or the second layer.

The watermark or pseudo-watermark may be made in various ways known to those skilled in the art, for example in a fibrous or polymer layer.

The watermark may be a pattern engraved or pressed into a fibrous layer during its manufacture. Such a watermark can for example be seen by transparency by creating thinning or overloads of pasta at the time of manufacture of the fibrous layer on a paper machine with round shape with a relief or recessed impression in the training fabric of the round form.

The watermark can still come from areas where the fibrous layer has been pressed onto a flat-bed paper machine by means of a filigree roller which has the embossing of the embossed watermark, which has the effect of strongly pressing certain areas of the fibrous layer. and to remove the water contained in the fibers at the time of formation of the fibrous layer in the wet part.

The pseudo-watermark can be produced in a finite fibrous layer by mechanical and / or chemical means by application of certain products, this drawing being always visible in transparency.

The pseudo-watermark may for example be produced by depositing or printing in certain zones of the fibrous layer a composition which modifies the transparency of the fibrous layer, in particular in order to produce light areas and dark areas, similar to those of a watermark, but without obtaining a result to obtain fineness and brightness variants comparable to those of a conventional watermark.

For example, the finished fibrous layer can be made transparent by applying, in particular areas, for example a generally oily composition which permanently crystallises the fibrous layer, for example a composition made of oil and transparent mineral material as described in the patent. US 2,021,141 or as for example a composition in the form of a wax combined with a solvent as described in the patent US 1,479,337 .

The finished fibrous layer can also be made transparent by locally applying a wax by heat transfer as described in US Pat. US 5,118,526 , a radiation-transmissive fluid-transparentizing composition as described in GB 1 489 084 , or a composition based on polyether, aliphatic isocyanate and alcohol, applied by printing, as described in DE 3,920,378 .

It is also possible to use a fibrous layer comprising a hot-melt material, for example polyethylene, as described in the patent EP 0 203 499 , which under the local action of heat will see its transparency vary.

The finished fibrous layer can be opacified, without, however, rendering it completely opaque, by applying, in certain zones, an opacifying agent which increases the opacity of the fibrous layer, as for example described in the patent application. FR 2 353 676 . The opacifying agent may for example be an aqueous suspension of a pigment or a filler or a solution of a chemical compound, a colored compound or a dye. This agent can be applied during the manufacture of the fibrous layer, on the fibrous web, and before its removal from the fabric, so that the agent penetrates the interstices of the web and causes a change in the opacity of the web to be treated in selected areas, after drying. This manufacturing technique has the disadvantage of requiring special devices rollers to apply the agent, and preferably employing a suction device to penetrate the agent in the interstices of the web.

It is also possible to carry out a pseudo-watermark according to the process described in the document W. WALENSKI, "Watermarks and Those That Are Not", Druckspiegel 52, No. 3: 66-68 (March 1997 ). This document describes a method of manufacturing a pseudo-watermark on uncoated paper, comprising applying under heat and pressure a marking piece, representing the pattern of the pseudo-watermark, on a sheet of rewetted paper.

A pseudo-watermark can also be made on an uncoated paper by applying a rewetting solution on one or more determined zones of the paper under heat and pressure so as to evaporate the solution and to densify the paper in the zone or zones determined. .

International demand WO 97/17493 also discloses the manufacture of coated paper having pseudo-watermarks resulting from a variation of the applied layer weight in specific areas, which induces a variation in thickness and opacity in areas where the layer weight is reduced or increases.

International demand WO 1999/014433 also discloses another method of manufacturing a pseudo-watermark on a coated paper, which provides for imaging in the paper after the drying step following the last coating operation, performing the steps in which a rewetting solution on at least one side of the coated paper, in one or more determined zones, and applying a pressure and heat in the area or areas of the coated paper so as to evaporate the solution and densify the coated paper in the area or areas relative to the rest of the paper.

The pseudo-watermark may finally be made mechanically by making marks by mechanical embossing of determined areas of the fibrous layer as described in the patent DE 3,718,452 .

The pseudo-watermark may also be made in a polymer layer by applying a composition capable of modifying its transparency.

The demand WO 91/07285 describes the printing on a synthetic support of a composition modifying the opacity of the support containing at least one mineral filler and at least one binder or a soluble or pigmentary dye. The composition is applied in specific areas and the support is then coated over its entire surface with a printable pigment composition according to the coating methods known to those skilled in the art.

The patent US 4,307,899 discloses an authentication card having a fingerprint formed on a support, preferably plastic, by the printing of colored layers partially overlapping. Areas printed with a single layer appear brightly in transmitted light and dark in reflected light, and areas printed with multiple layers superimposed appear dark in transmitted light and clear in reflected light, thus producing a watermarked effect. By changing the number of layers, it is possible to obtain multiton effects.

The pseudo-watermark can still be made in a polymer layer by the use of mechanical means.

For example, a pseudo-watermark can be made on a sheet of a polymeric material by passing it between two rollers, one of which bears a hollow or raised pattern as to form an impression as described in FIG. EP 0 655 316 . The sheet is then stretched so that under transmitted light, the pattern appears black and white corresponding to the areas marked in relief or recessed with the roller.

International demand WO 2007/016148 also discloses a plastic layer which can be deformed, in particular stamped by embossing or de-embossing, to form an image which appears as a watermark, then laminated without the image formed being damaged.

The pseudo-watermark may finally be made on a polymer layer using electromagnetic radiation, such as a laser.

The demand EP 1,518,661 describes for example a method for producing a pseudo-watermark on a coil sheet by electromagnetic irradiation of certain areas and stretching of the sheet so as to obtain a stretched sheet having transparent areas corresponding to the irradiated areas.

The watermarks or pseudo-watermarks of the first and second layers can be made according to any of the methods described above.

One of the layers may comprise a watermark and the other a pseudo-watermark, or the two layers may each comprise a watermark or each a pseudo-watermark.

The interlayer may be monolayer or multilayer.

The intermediate layer may be a polymer layer or comprise one or more polymer layers.

According to a preferred embodiment of the invention, the polymer layer may be in the form of a film. The film can be a foamed film or not. By way of example, the polymer layer may comprise a polyvinyl chloride (PVC) film, polyethylene terephthalate (PET), polycarbonate (PC), polyester carbonate (PEC), polyethylene terephthalate glycol (PETG), acrylonitrile butadiene styrene (ABS) or a light-collecting film, for example of the "waveguide" type, for example a luminescent film based on polycarbonate marketed by Bayer under the name LISA®.

The intermediate layer may be a fibrous layer or comprise one or more fibrous layers.

The fibrous layer may for example be based on cellulose fibers, in particular cotton fibers, and / or synthetic fibers such as for example polyamide and / or polyester fibers. In particular, the interlayer may be a translucent tracing paper.

The first layer and / or the second layer may be fibrous or polymeric layers.

According to a particular case of the invention, the first layer and / or the second layer are fibrous layers, in particular based on cellulose fibers, in particular on cotton fibers, and / or on synthetic fibers such as, for example, staple fibers. polyamide and / or polyester.

According to another particular case of the invention, the first layer and / or the second layer are polymer layers, especially as described above. In particular, the first layer and / or the second layer may be polymeric layers with cavities and / or mineral fillers so as to make them partially opaque. The first and / or second layer may be coextruded, made from at least one polymeric material, and have a core layer and at least one skin layer, the core layer having voids. The "core layer" corresponds to a base layer further from the surface of the first layer or layer than the "skin layer" which corresponds to a surface layer. The first layer and / or the second layer may in particular be made as described in the applications EP 0 470 760 and EP 0 703 071 . For example, it is possible to use, for the first and / or the second layer, a film based on polyethylene stretched marketed under the name of Polyart® by the company ARJOWIGGINS or a silica-filled polyethylene film marketed under the name Teslin® by the company. PPG INDUSTRIES company. In this case, the first and second layers may each comprise a pseudo-watermark, for example made using a laser, by stretching and coating with a printability layer, as described in FIG. EP 1,518,661 .

According to a preferred embodiment of the invention, the intermediate layer may be a polymer layer previously extruded or laminated on the first and second layers, for example extruded hot or cold. As examples, as an extruded polymer, polyethylene or a mixture of polyethylene and ethylene vinyl acetate may be used.

The interlayer may be further impregnated or coated on the first and second layers. This layer may comprise a translucent chemical compound, for example a dispersed polymer derived from a polymer put into an aqueous dispersion (latex), in particular an acrylic polymer, for example a water-soluble polymer, in particular a polyvinyl alcohol or for example a foam of polymer (that is to say a composition comprising gaseous bubbles, in particular air).

The interlayer may be assembled to the first and second layers with one or more adhesive layers in liquid form or in the form of movie. Alternatively, the spacer layer may be joined to the first and second layers by fusion or welding.

The intermediate layer may also be or include a layer of adhesive, for example an adhesive film which may also serve to assemble the first and second layers. This adhesive film may be for example a polyethylene film.

In a particular case, the intermediate layer may be pre-coated on at least one of its faces with a pressure-sensitive or heat-reactive adhesive composition, this composition being applied cold or hot, in liquid form, by extrusion or by lamination.

In another particular case, the inner faces of the first and second layers may be pre-coated with a pressure-sensitive or heat-reactive adhesive composition, which composition is applied cold or hot, in liquid form, by extrusion or by lamination.

The diffusing nature of the light of the interlayer may come from the refractive index of the interlayer, its composition, its thickness and / or also its surface irregularities.

In a particular case, the surface irregularities of the intermediate layer can be obtained by embossing or graining this surface. The surface irregularities can also be obtained by the irregularities of the surface which supports the layer, which is for example the case of an intermediate layer of polymer extruded on the surface of a first fibrous layer.

In another particular case, the intermediate layer is a layer having cavitations conferring a diffusing character, for example bubbles.

According to another particular case of the invention, the interlayer is a layer comprising a diffusing filler chosen in particular from mineral pigments, in particular kaolin or titanium dioxide, and organic pigments, in particular polystyrene beads or polyurethane.

The interlayer may have a thickness different from at least one of the first and second layers. The interlayer may also have a different width and / or length, especially smaller, of the width and / or length of at least one of the first and second layers.

The interlayer may extend over the entire surface of the first and second layers.

According to a particular case of the invention, the interlayer is partial and extends only over a portion of the surface of the first and second layers of the sheet. In this case, the intermediate layer preferably extends over an extent of the first and second layers sufficient to cover the filigree or pseudo-watermarked parts of these layers.

According to another particular case of the invention, the intermediate layer extends at a portion of the sheet, preferably from one edge to the other of the sheet, in a zone facing at least one watermark or pseudo-watermark, for example to form a band.

According to a particular case of the invention, the intermediate layer is partial and extends only over part of the surface of at least one of the watermarks or pseudo-watermarks. Thus, a part of the watermark or pseudo-watermark is visible only from one side of the sheet while another part (the part not covered by the interlayer) is visible on both sides of the sheet in light transmitted.

• des colorants et/ou des pigments luminescents et/ou des pigments interférentiels et/ou des pigments à cristaux liquides, notamment sous forme imprimée ou incorporée dans la couche intercalaire,
• des colorants et/ou des pigments photochromes ou thermochromes, notamment sous forme imprimée ou incorporée dans la couche intercalaire,
• un absorbeur ultraviolet, notamment sous forme enduite ou incorporée dans la couche intercalaire,
• un matériau spécifique collecteur de lumière,
• une structure de diffraction,
• une couche biréfringente ou polarisante,
• un traceur lisible automatiquement ayant des caractéristiques spécifiques et mesurables de luminescence (par exemple fluorescence, phosphorescence), d'absorption de la lumière (par exemple ultraviolet, visible ou infrarouge), d'activité Raman, de magnétisme, d'interaction micro-ondes, d'interaction aux rayons X ou de conductivité électrique, et toute combinaison de ces éléments de sécurité entre eux ou avec d'autres éléments de sécurité,
• un dispositif électronique (comme une puce électronique).

According to a particular case of the invention, the intermediate layer comprises one or more security elements, chosen inter alia from:

• dyes and / or luminescent pigments and / or interferential pigments and / or liquid crystal pigments, in particular in printed form or incorporated in the interlayer,
• dyes and / or photochromic or thermochromic pigments, especially in printed form or incorporated in the interlayer,
• an ultraviolet absorber, especially in the form coated or incorporated in the interlayer,
• a specific material light collector,
• a diffraction structure,
• a birefringent or polarizing layer,
• an automatically readable tracer with specific and measurable luminescence characteristics (eg fluorescence, phosphorescence), light absorption (eg ultraviolet, visible or infrared), Raman activity, magnetism, microwave interaction , X-ray interaction or conductivity electric, and any combination of these security elements with each other or with other security features,
• an electronic device (such as an electronic chip).

• des colorants et/ou des pigments luminescents et/ou des pigments interférentiels et/ou des pigments à cristaux liquides, notamment sous forme imprimée ou incorporée dans la première et/ou la seconde couche,
• des colorants et/ou des pigments photochromes ou thermochromes, notamment sous forme imprimée ou incorporée dans la première et/ou la seconde couche,
• un absorbeur ultraviolet, notamment sous forme enduite ou incorporée dans la première et/ou la seconde couche,
• un matériau spécifique collecteur de lumière,
• une structure de diffraction,
• une couche biréfringente ou polarisante,
• un traceur lisible automatiquement ayant des caractéristiques spécifiques et mesurables de luminescence (par exemple fluorescence, phosphorescence), d'absorption de la lumière (par exemple ultraviolet, visible ou infrarouge), d'activité Raman, de magnétisme, d'interaction micro-ondes, d'interaction aux rayons X ou de conductivité électrique, et toute combinaison de ces éléments de sécurité entre eux ou avec d'autres éléments de sécurité,
• un dispositif électronique (comme une puce électronique).

The first and / or second layer may also include one or more security elements. The security element or elements can for example be chosen from:

• dyes and / or luminescent pigments and / or interferential pigments and / or liquid crystal pigments, especially in printed form or incorporated in the first and / or second layer,
• dyes and / or photochromic or thermochromic pigments, especially in printed form or incorporated in the first and / or second layer,
• an ultraviolet absorber, especially in the form coated or incorporated in the first and / or second layer,
• a specific material light collector,
• a diffraction structure,
• a birefringent or polarizing layer,
• an automatically readable tracer with specific and measurable luminescence characteristics (eg fluorescence, phosphorescence), light absorption (eg ultraviolet, visible or infrared), Raman activity, magnetism, microwave interaction , X-ray interaction or electrical conductivity, and any combination of these security elements with each other or with other security elements,
• an electronic device (such as an electronic chip).

• un fil de sécurité incorporé par exemple dans la masse d'une des couches ou en fenêtre, comportant éventuellement une impression imprimée en positif ou en négatif, un agent fluorescent procurant un effet métallique, goniochromatique ou holographique, avec ou non une ou plusieurs parties démétallisées,
• un foil métallisé, goniochromatique ou holographique,
• une couche à effet optique variable à base de pigments interférentiels ou de cristaux liquides,
• un élément de sécurité plat et de format relativement petit tel qu'une planchette, visible ou non visible, notamment luminescent,
• des particules ou agglomérats de particules de pigments ou colorants de type HI-LITE, visibles ou non visibles, notamment luminescents,
• des fibres de sécurité, notamment métalliques, magnétiques (à magnétisme doux et/ou dur), absorbantes ou excitables aux ultraviolets, au visible ou à l'infrarouge, et en particulier le proche infrarouge (NIR).

The security element or elements present in one of the first and second layers or in these first and second layers can still be chosen, among others, from:

• a security thread incorporated for example into the mass of one of the layers or into a window, optionally comprising a positive or negative printed impression, a fluorescent agent providing a metallic, goniochromatic or holographic effect, with or without one or more demetallized parts ,
• a foil metallized, goniochromatic or holographic,
• a layer with a variable optical effect based on interferential pigments or on liquid crystals,
• a flat and relatively small security element such as a board, visible or non-visible, in particular luminescent,
• particles or agglomerates of pigment particles or dyes of the HI-LITE type, visible or non-visible, in particular luminescent,
• security fibers, in particular metallic, magnetic (with soft magnetism and / or hard), absorbing or excitable with ultraviolet, visible or infrared, and in particular the near infrared (NIR).

According to a particular case of the invention, the first layer and / or the second fibrous layer are provided with at least one through opening ("window"). In particular, the first and second layers may each comprise at least one through opening, at least one opening of the first layer and an opening of the second layer facing each other, for example at the level of the intermediate layer, so as to create a transparent or translucent area in the sheet.

According to a particular case of the invention, the first layer and / or the second layer are tinted, the watermarks or pseudo-watermarks then appear tinted. By "tinted" you have to understand not white.

The first layer and / or the second layer may be iridescent or pearlescent, for example with interferential pigments.

According to a particular case of the invention, the security elements, in particular the watermarks or pseudo-watermarks, of the first and / or the second layer and the security elements of the intermediate layer are placed at the mark.

In one example, the first and / or second fibrous layer is a paper layer comprising a web face (i.e., the face that has been in contact with the web of the paper machine on which the paper pulp) and this canvas face is located towards the inside of the sheet. This can improve the observation of the watermark or pseudo-watermark because the canvas face is smoother and thus the intensities of the transmitted light are more important. Also preferably the interlayer, when coated, extruded or laminated, is located on the web face of the first and / or second layer.

Also preferably, the first layer and the second layer respectively constitute the front face and the back side of the sheet. These layers are therefore the outer layers of the leaf. However, the first layer and / or the second layer may be coated with a transparent pigmented layer, as for example that described in the application WO02 / 20902 .

According to an exemplary implementation of the invention, the first watermark or pseudo-watermark and the second watermark or pseudo-watermark are different. For example, the first watermark or pseudo-watermark and the second watermark or pseudo-watermark may be complementary. They can be complementary in their visual effect or in relation to a concept or an image. For example, in the case of a security document, the first watermark or pseudo-watermark may have a national emblem and a second watermark or pseudo-watermark on the other hand or a text in the case of a security document. a bank note can be put respectively a portrait and the value of the ticket.

According to another example of implementation of the invention, the first watermark or pseudo-watermark and the second watermark or pseudo-watermark are identical, and preferably placed symmetrically. In the case of an authentication, it may be interesting to verify this identity between the watermarks or pseudo-watermarks (for example a character always looking on the same side regardless of the observed face).

According to a particular embodiment of the invention, the first watermark or pseudo-watermark and the second watermark or pseudo-watermark are at least partially opposite one another.

The sheet may be a security sheet and may further comprise another security element such as a security thread, a hologram, security fibers, thermochromic compounds, photochromic or interferential (liquid crystals, iridescent compounds) or a electronic device (such as an electronic chip).

The grammage of the sheet according to the invention depends on the intended application, and for example it is between 80 and 150 g / m ² .

The invention also relates to the method of manufacturing said sheet.
More specifically, it is possible to form a first layer in which a first watermark or pseudo-watermark is created, to form a second layer in which a second watermark or pseudo-watermark is created, and to have an intermediate layer between the said first and second layers. These may be as described above.

In particular, said first and second layers can each be made by draining a pulp suspended in the fabric of a machine. paper with embossings and / or raised relief creating watermarks or pseudo-watermarks. It may be to manufacture these layers using two form tanks (round shapes) or using a shaped tank for one of the layers and a "train" for the other layer.

These layers can also be formed using a flat table machine, possibly including several tables, and form the watermarks with a filigree roller. This method can be advantageous in the case where one wants a watermark seed, that is to say, repeated over the entire surface of the layer.

The layers can be dyed by coloring in a sizing press, in order to obtain colored watermarks or pseudo-watermarks.

According to an exemplary implementation of the invention, the intermediate layer is deposited by surface treatment, in particular by spraying, by gluing press or by coating, of a compound on the inner face of said first layer and / or said second layer. This can be done in particular on the wet fibrous layers during their manufacture on the paper machine or after drying.

One of the coating devices used can be used in the paper industry, for example an air knife coater or a curtain coater. These devices make it possible to have a layer which remains sufficiently on the surface and which marries the irregularities of surface on which it is deposited.

According to one particular embodiment, a polymer layer is extrusion deposited on the first and / or second layer and then the two layers are assembled by hot pressing (lamination), the extruded polymer layer or layers forming the interlayer.

According to another exemplary embodiment of the invention, said first and second filigree or pseudo-watermarked layers are counteracted with a compound forming the interlayer, in particular with an adhesive compound or a foam, the latter possibly being hot-meltable or not.

According to an exemplary implementation of the invention, the intermediate layer is laminated or laminated between the first and second layers. For example, a grained polymer film is laminated between two sheets of paper.

• une première couche fibreuse comportant un premier filigrane ou pseudo-filigrane,
• une seconde couche fibreuse comportant un second filigrane ou pseudo-filigrane,
• une couche intercalaire formée d'une première couche polymère extrudée sur la première couche fibreuse et d'une seconde couche polymère extrudée sur la seconde couche fibreuse.

According to another example of implementation of the invention, the sheet comprises:

• a first fibrous layer comprising a first watermark or pseudo-watermark,
• a second fibrous layer comprising a second watermark or pseudo-watermark,
• an interlayer formed of a first polymeric layer extruded on the first fibrous layer and a second polymeric layer extruded on the second fibrous layer.

For example, each extruded layer has a basis weight of about 20 g / m ² .

The extruded layers may be in direct contact or comprise a film (quasi) transparent inserted between them which may itself comprise security elements or an electronic device. In general, the intermediate layer may comprise several layers themselves translucent and having a diffusing effect. These layers can be directly in contact or separated by (quasi) transparent layers which may optionally include security elements, for example an electronic device.

The invention also relates to an article comprising a sheet as defined above.

In particular, the article may be chosen from security documents, printing-writing papers, for example letterheads, art papers, watercolor papers or packaging, especially those intended to contain luxury products.

The security document may be chosen from identity documents, in particular an identity card or a passport, the means of payment, in particular banknotes, checks, vouchers or vouchers, admission tickets to cultural or sports events, transport tickets.

It can also be a security document chosen from certificates of authenticity, guarantee certificates or secure packaging, in particular for medicines, electronic parts, spare parts, perfumes and secure labels.

• La figure 1 représente une vue de la face recto d'une feuille selon l'état de la technique dépourvue de couche intercalaire.
• La figure 2 représente une vue de la face verso de la feuille de la figure 1.
• La figure 3 représente une vue en coupe d'une feuille selon l'invention, comportant des pseudo-filigranes.
• La figure 4 représente une vue de face des feuilles des figures 3 et 6 selon leur face recto observée en lumière transmise.
• La figure 5 représente une vue de face des feuilles des figures 3 et 6 selon leur face verso observée en lumière transmise.
• La figure 6 représente une vue en coupe d'une autre feuille selon l'invention comportant des filigranes.
• La figure 7 représente une vue en coupe d'un autre exemple de feuille selon l'invention avec une couche intercalaire de dimensions réduites.
• Les figures 8 et 9, 10 et 11, et 12 et 13 représentent des vues de face, recto et verso, de feuilles 1 selon l'invention avec des positionnements variables des filigranes ou pseudo-filigranes.

The invention will be better understood in the following reading of the non-limiting examples of implementation thereof and the review of the figures of the accompanying drawings, schematic and partial.

• The figure 1 represents a view of the front face of a sheet according to the state of the art devoid of interlayer.
• The figure 2 represents a view of the reverse side of the sheet of the figure 1 .
• The figure 3 represents a sectional view of a sheet according to the invention, comprising pseudo-watermarks.
• The figure 4 represents a front view of the leaves of figures 3 and 6 according to their front face observed in transmitted light.
• The figure 5 represents a front view of the leaves of figures 3 and 6 according to their verso side observed in transmitted light.
• The figure 6 represents a sectional view of another sheet according to the invention comprising watermarks.
• The figure 7 is a sectional view of another example of a sheet according to the invention with an interlayer of reduced dimensions.
• The Figures 8 and 9 , 10 and 11, and 12 and 13 represent front views, front and back, sheets 1 according to the invention with variable positions of watermarks or pseudo-watermarks.

We have shown respectively on Figures 1 and 2 , in front view, the front face and the back side of an example sheet according to the state of the art.

The sheet has first and second fibrous or polymeric layers.

The first layer may comprise a watermark or pseudo-watermark representing for example an emblem, and the second layer may comprise another watermark or pseudo-watermark corresponding in this example to the text "XYZY".

The two watermarks or pseudo-watermarks are partially superimposed on each other. Alternatively, they could be totally superimposed on one another or disjointed, for example contiguous to one another.

When we observe the sheet in transmitted light, the front side as represented on the figure 1 or on the back side as shown on the figure 2 you can see both watermarks or pseudo-watermarks simultaneously. In this way, the latter can combine, for example to form a third pattern resulting from this combination.

The figure 3 represents, in sectional view, an example of sheet 1 according to the invention.

The sheet 1 comprises a first layer 2 and a second layer 3 may be as described above, and an intermediate layer 6 may include the characteristics described above, extending for example over the entire surface of the first and second layers 2 and 3.

The first layer 2 and the second layer 3 respectively comprise a pseudo-watermark 4 and a pseudo-watermark 5, as described above, partially superimposed on one another. Alternatively, the pseudo-watermarks 4 and 5 may be totally superimposed on one another or disjoint, for example contiguous to one another.

When the sheet 1 is observed in transmitted light on the side of the first layer 2 (front side) as shown in FIG. figure 4 only the pseudo-watermark 4 of the first layer 2 is observed. Similarly, when the sheet 1 is observed in light transmitted on the side of the second layer 3 (back side) as shown in FIG. figure 5 only the pseudo-watermark 5 of the second layer 3 is observed.

Thus, the sheet 1 according to the invention can make it possible to prevent the combination of the pseudo-watermarks 4 and 5 with the observation in transmitted light.

The figure 6 represents another example of sheet 1 according to the invention, the obtaining of which is detailed hereinafter in example 1.

The figure 7 represents in section, schematically for ease of understanding, another example of sheet 1 according to the invention, comprising a first layer 2 and a second layer 3 which may be as described above and an intermediate layer 6.

In this example, the interlayer 6 has dimensions, including a width, smaller than those of the first 2 and second 3 layers. The interlayer 6 may for example correspond to a translucent band and diffusing light, monolayer or not.

The Figures 8 and 9 respectively represent the front and the back of a sheet 1 according to the invention, which may correspond to the sheet of the figure 7 .

The sheet 1 comprises an interlayer 6 in the form of a strip.

The first layer 2 comprises several watermarks or pseudo-watermarks 4, in particular a watermark or pseudo-watermark 4 located completely at the level of the intermediate layer 6.

The second layer 3 also comprises several watermarks or pseudo-watermarks 5, in particular a watermark or pseudo-watermark 5 located completely at the level of the intermediate layer 6.

When sheet 1 is observed in transmitted light, it is thus possible to observe a combination of watermarks or pseudo-watermarks 4 and 5 between them outside the layer insert 6, as can be seen from Figures 8 and 9 . On the other hand, at the level of the interlayer 6, the watermarks or pseudo-watermarks 4 and 5 do not combine.

The Figures 10 and 11 illustrate the possibility for watermarks or pseudo-watermarks 4 and 5 of a sheet 1 according to the invention to be totally superimposed on one another. In this example, the sheet 1 comprises a not shown intermediate layer extending over the entire surface of the first and second layers 2 and 3. On the front of the sheet 1 shown in FIG. figure 10 only the watermark or pseudo-watermark 4 of the first layer 2 is observed. On the back of the sheet 1 shown in FIG. figure 11 only the watermark or pseudo-watermark 5 of the second layer 3 is observed.

The Figures 12 and 13 finally illustrate the possibility for watermarks or pseudo-watermarks 4 and 5 of a sheet 1 according to the invention to be disjoint. In this example again, the sheet 1 comprises a not shown intermediate layer extending over the entire surface of the first and second layers 2 and 3.

As above, only the watermark or pseudo-watermark 4 on the front side of the sheet 1, shown in FIG. figure 12 , and only the watermark or pseudo-watermark 5 on the back of the sheet 1, shown in FIG. figure 13 .

Example 1

A sheet 1 according to the invention of paper type security is manufactured.
A first fibrous layer 2 having a watermark 4 is formed on a round-shaped paper machine having a shaped bowl, by draining a pulp suspension having cellulose fibers on the web of the shape, the watermark being formed according to the embossings that comprise the fabric, this layer is dried. This layer (paper sheet) has a thickness of 100 microns, for example.

In the same manner, a second fibrous layer 3 having a watermark 5 different from the watermark 4 is formed and dried. Its thickness is also 100 microns for example.

The watermarks are different, the watermark 4 represents for example an emblem and the watermark 5 represents for example a text "XYZY".

On an extruder, a polymer layer is extruded, for example at a rate of 20 g / m ² in dry, for example polyethylene (PE), on the fabric side of the first layer 2 (dried), and an extruded sheet having surface irregularities induced by the irregularities of the surface of the fibrous layer. This layer of extruded polymer forms the intermediate layer 6, its diffusing nature originating from the surface irregularities.

In a laminator, at a temperature of 90 ° C. and 180 ° C. for example, the layer 2 thus coated with a layer of polymer is bonded together with the (dried) fibrous layer 3 by applying the extruded face of the layer 2 against the canvas face of layer 3.

A sheet 1 according to the invention is thus obtained. By observing the sheet facing the layer 2, we see the watermark 4 in transmitted light, but we do not see the watermark 5, as shown in FIG. figure 4 ; in the same way, only the watermark 5 is seen by observing the sheet in transmitted light opposite the layer 3, as illustrated in FIG. figure 5 .

Example 2

A first fibrous layer having a first watermark is formed on a round shaped paper machine having a shaped bowl, by draining a pulp suspension having cellulose fibers on the web of the form, the watermark being formed according to the embossings that comprise the fabric, this layer is dried.

In the same way a second fibrous layer is formed having a second watermark different from the first and dried.

On an extruder, a polymer layer, for example polyethylene (PE), is extruded on the fabric face of the first (dry) layer, the polymer layer respecting the relief of the fibrous layer. An extruded sheet is thus obtained with surface irregularities.

Likewise, a layer of polymer, for example polyethylene, is extruded onto the web face of the second (dry) layer so as to obtain an extruded sheet with surface irregularities.

The two layers thus coated with a polymer layer are hot-bonded, extruded face against extruded face. The two extruded polymer layers form an interlayer having a diffusing character.

A sheet according to the invention is thus obtained. By observing the sheet in transmitted light, we see only one watermark at a time, depending on the face observed.

Example 3

A sheet according to the invention of the security paper type is formed on a flat-table paper machine comprising two forming tables. A pulp suspension comprising cellulose fibers is driped onto the fabric of each table to form respective fibrous layers each comprising seed watermarks. One layer of a polymer, for example a translucent acrylic polymer in the form of a latex (polymer in stabilized aqueous dispersion), is deposited on the fabric side of one of the layers, for example by air-jet coating, and having a high viscosity, so as to form a layer on the surface of the fibrous layer. Then the two layers are assembled by pressing them against each other, the polymer layer being located between the fibrous layers to form said intermediate layer, its diffusing nature coming from its surface irregularities (induced by that of the fibrous layer ).

Thus a sheet according to the invention is obtained, it is seen by observing the sheet in transmitted light that the watermarks of one of the layers according to the observed face.

Example 4

A first fibrous layer is formed having a first watermark made partly wet on a paper machine.

A second fibrous layer is formed comprising a second watermark also made partly wet on a paper machine.

The intermediate layer used is in the form of a translucent and light-diffusing complexing film made of thermoplastic polymer, in particular polyethylene.

The first fibrous layer, the interlayer and the second fibrous layer are heat-assembled, without pressure or with moderate pressure, so that the interlayer is sandwiched between the two fibrous layers and the watermarks of the two fibrous layers are for example superimposed.

A sheet according to the invention is thus obtained which, observed in transmitted light, is such that the first watermark is observable only on the side of the first layer and such that the second watermark is only observable on the side of the second layer. .

Example 5

A first layer is formed using a flexible synthetic support, for example made of polyethylene, on which a first mark is deposited, located on the outer surface of the support, for example by a layer of a composition modifying the opacity and non-localized way on this same face a printability layer according to WO 91/07285 so as to obtain a synthetic support with a first pseudo-watermark.

A second layer is formed by means of a flexible synthetic support, for example made of polyethylene, on which is deposited, on the outside surface of the support, a second mark, constituted for example by a layer of a composition modifying the opacity and non-localized way on this same face a printability layer according to WO 91/07285 , so as to obtain a synthetic support with a second pseudo-watermark.

The translucent and light-diffusing interlayer used consists, for example, of a polyethylene laminating film which has a softening temperature lower than that of the synthetic supports used to form the first and second layers.

The softening temperature of the laminating film, with or without pressure, is hot-bonded to the first and second layers and the interlayer, the printability layers being located on the outside of the sheet, so that the interlayer is taken between the first and second layers and that the first and second peudo-watermarks are for example superimposed.

A sheet according to the invention is obtained which, observed in transmitted light, is such that the first pseudo-watermark is observable only on the side of the first layer and such that the second pseudo-watermark is observable only on the side of the first layer. the second layer.

Example 6

Forming a first fibrous layer comprising a thermally heat-sensitive material and having a first pseudo-watermark in its thickness according to EP 0 203 499 .

Forming a second fibrous layer comprising a thermally heat-sensitive material and having a second pseudo-watermark in its thickness according to EP 0 203 499 .

The inner faces of the first and second layers are pre-coated with a layer of a transparent pressure-sensitive adhesive.

The intermediate layer used is in the form of a translucent and light-diffusing film, for example polyethylene terephthalate.

The first fibrous layer, the interlayer and the second fibrous layer are cold-pressed and pressure-bonded so that the interlayer is sandwiched between the first and second fibrous layers using the layers of pressure and that the first and second pseudo-watermarks are for example superimposed.

A sheet according to the invention is thus obtained which, observed in transmitted light, is such that the first pseudo-watermark is observable only on the side of the first layer and such that the second pseudo-watermark is observable only on the side of the second layer.

Example 7

Simultaneously, a first layer of fibrous material having a first watermark in the form of repeating patterns present on the entire surface of the first layer is formed on a paper machine with a round shape in the form of two layers, the watermark being made partly wet, and a second layer fibrous material comprising a second watermark in the form of repeated patterns present throughout the surface of the second layer, watermark the watermark being made partly wet.

Pre-coated a film of luminescent polycarbonate such as for example the film sold under the name LISA® by the company Bayer, with a coating of a heat-sealing varnish. Then, the film is cut into strips of width greater than those of the first and second watermarks. An interlayer in the form of a strip is thus obtained.

The interlayer is inserted between the first and second fibrous layers on the twin-jet paper machine so that the interlayer in the form of a strip is located between the two fibrous layers at the two watermarks which, due to their extension over the entire surface of the layers are themselves superimposed. During the drying phase of the sheet, the heat-sealing varnish on both sides of the interlayer is reactivated and allows the attachment of the interlayer with the two fibrous layers during cooling.

A sheet according to the invention is thus obtained which, observed in transmitted light, is such that the first watermark and the second watermark are both observable. combined on the side of the first fibrous layer but also on the side of the second fibrous layer out of the band corresponding to the intermediate layer. On the other hand, at the level of the band, the first watermark is observable only on the side of the first fibrous layer and the second watermark only on the side of the second fibrous layer. There is no possible combination of watermarks at the band, especially because of its diffusing power.

Example 8

From two polyethylene supports comprising silica fillers, for example two Teslin® films marketed by PPG INDUSTRIES, a first pseudo-watermark and a second pseudo-watermark are produced on each of the supports by hot embossing, such as described in WO 2007/016148 .

An interlayer is used in the form of a PET film pre-glued with an adhesive of polyethylene and ethylene vinyl acetate (PE / EVA) on each of its faces.

The first support is hot assembled with the first pseudo-watermark, the intermediate layer and the second support with the second pseudo-watermark so that the intermediate layer is taken between the two supports and that the two pseudo-watermarks for example, be superimposed.

A sheet according to the invention is thus obtained which, observed in transmitted light, is such that the first pseudo-watermark is observable only on the side of the first layer formed by the first support and the second pseudo-watermark is not visible. observable only on the side of the second layer formed by the second support.

Example 9

First and second fibrous layers are formed, each having a printability layer at their surface.

An intermediate layer is used in the form of a translucent and light diffusing film of polyethylene.

The first fibrous layer, the interlayer and the second fibrous layer are assembled so that the interlayer is sandwiched between the two fibrous layers. The hot obtained assembly is laminated, the printability layers being located outside.

Each of the printability layers, for example in a juxtaposed manner, is then made with first and second pseudo-watermarks according to the process described in FIG. WO 1999/014433 that is, applying a rewetting solution on each of the printability layers at the pseudo-watermarks and then applying pressure and heat to the areas of the reworked printability layers so as to evaporate the solution. and densifying the fibrous layers in these areas.

A sheet according to the invention is thus obtained which, observed in transmitted light, is such that the first pseudo-watermark is observable only on the side of the first layer and such that the second pseudo-watermark is observable only on the side of the second layer.

Example 10

As first and second layers, two polyethylene films marketed under the name Polyart® by the company ARJOWIGGINS are used.

On each of the polyethylene films, a first and a second pseudo-watermark are produced using electromagnetic radiation, for example a laser, for example according to the method described in FIG. EP 1,518,661 that is to say by electromagnetic irradiation of certain zones and stretching so as to obtain transparent zones corresponding to the irradiated zones. Then, if necessary, a printability layer is applied to at least one face of each of the polyethylene films. Finally cutting, for example by punch, a through opening on each of the polyethylene films.

An interlayer is used in the form of a translucent and light-diffusing film of transparent polyester.

The first layer, the interlayer and the second layer are assembled by means of pressure-sensitive adhesives so that the interlayer is sandwiched between the two layers and the through-openings of the first and second layers are formed. are located opposite one another. The cold set is laminated, the printability layers being located outside.

A sheet according to the invention is thus obtained which, observed in transmitted light, is such that the first pseudo-watermark is observable only on the side of the first layer and such that the second pseudo-watermark is observable only on the side of the second layer. The The sheet thus obtained also comprises, at the through apertures of the first and second layers, a totally translucent zone.

Example 11

A first and a second fibrous layer is formed, each having a watermark on a flat-bed paper machine, the watermarks being formed by means of a filigree roll. At least one through aperture is made, for example by laser cutting, on each of the first and second fibrous layers.

An interlayer is used in the form of a light-collecting strip or patch, for example of the "waveguide" type, for example a strip or a luminescent patch based on polycarbonate marketed by the Bayer company under the name LISA®. In an area of the interlayer, a pattern is made by means of microperforations, for example a portrait, showing the "waveguide" luminescent effect of the interlayer.

The first layer, the interlayer and the second layer are adhesively bonded together so that the interlayer is sandwiched between the two layers, particularly at the watermarks, and the microperforated zone of the interlayer and the through openings of the first and second fibrous layers are located opposite.

A sheet according to the invention is thus obtained which, observed in transmitted light, is such that the first pseudo-watermark is observable only on the side of the first layer at the intermediate layer in the form of a strip or patch and such that the second pseudo-watermark is observable only on the side of the second layer at the intermediate layer in the form of band or patch. The sheet thus obtained also makes it possible to observe the "waveguide" effect of the interlayer sheet at the through openings of the first and second layers.

The expression "comprising a" or "comprising a" is synonymous with "comprising at least one" or "comprising at least one", unless the opposite is specified.

Claims (13)

1. Sheet (1) comprising:

   - a recto face and a verso face,

   - a first layer (2) comprising at least one watermark or a pseudo-watermark (4),

   - a second layer (3), and

   - an intermediate layer (6) placed between the first and second layers (2, 3),

   the intermediate layer being translucent and scattering light, and comprising:

   • cavitations,

   • scattering fillers, and/or

   • surface irregularities,

   the sheet (1) being such that said watermark or pseudo-watermark (4) is observable in transmitted light, at least partially, only on one of the faces of said sheet (1) .
2. Sheet according to Claim 1, the second layer (3) comprising at least one second watermark or pseudo-watermark (5), and the sheet being such that said first watermark or pseudo-watermark (4) is observable in transmitted light, at least partially, only on the recto face of said sheet (1) level with the intermediate layer (6) and such that said second watermark or pseudo-watermark (5) is observable in transmitted light, at least partially, only on the verso face of said sheet (1) level with the intermediate layer (6).
3. Sheet according to Claim 1 or 2, characterized in that said intermediate layer (6) extends over all the surface of said first and second layers (2, 3).
4. Sheet according to Claim 1 or 2, characterized in that said intermediate layer (6) extends partially over the surface of said first and second layers (2, 3) of the sheet (1), sufficiently to at least partially cover the watermarked or pseudo-watermarked portions of these layers.
5. Sheet according to Claim 1 or 2, characterized in that said intermediate layer (6) extends over one portion of the sheet (1), preferably from one edge to the other of the sheet (1) in a zone facing at least one watermark or pseudo-watermark, in particular so as to form a strip.
6. Sheet according to any one of Claims 2 to 5, characterized in that said watermarks or pseudo-watermarks (4, 5) of the first and second layers (2, 3) are at least partially superposed with each other level with the intermediate layer (6).
7. Sheet according to any one of Claims 2 to 6, characterized in that said intermediate layer (6) is a bubble-containing layer.
8. Sheet according to any one of Claims 2 to 7, characterized in that said first watermark or pseudo-watermark (4) and said second watermark or pseudo-watermark (5) are different.
9. Sheet according to any one of Claims 2 to 8, characterized in that said first watermark or pseudo-watermark (4) and said second watermark or pseudo-watermark (5) are complementary.
10. Sheet according to any one of Claims 2 to 9, characterized in that said intermediate layer and/or the first and second layers (2, 3) comprise security elements other than a watermark or pseudo-watermark.
11. Sheet according to Claim 10, characterized in that the security elements of the first and second layers and the security elements of the intermediate layer are placed in register.
12. Article comprising a sheet (1) such as described in or manufactured according to one of the preceding claims.
13. Article according to the preceding claim, characterized in that it is chosen among security documents, printing/writing paper, in particular letterheads, art paper, in particular paper for watercolours, or packages, in particular those intended to contain luxury items, identity documents, in particular an identity card or a passport, payment means, in particular banknotes, cheques, vouchers or coupons, tickets for entrance to cultural or sporting events, tickets for travel, authenticity certificates, certificates of guarantee or security packaging, in particular for drugs, electronic components, spare parts, perfumes, and security labels.

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