EP1766138B1 - Knitted structure designed to be incorporated in a sheet material - Google Patents

Abstract

The invention concerns a sheet material, characterized in that it incorporates at least one knitted structure. The invention also concerns a document and a base fabric comprising said sheet material, as well as a method for making said material. The invention further concerns a knitted structure comprising at least one authenticating and/or identifying element, as well as a method for authenticating and/or identifying a document or a knitted structure.

Description

The present invention particularly relates to a sheet material and a document or a printing medium comprising or consisting of such a sheet material.

There is a need to further improve the protection of security or valuable documents against forgery.

In addition, bank notes are often folded in use, which weakens them and can lead to rips after a certain period of use. There is thus also a need to mechanically reinforce security or value documents, especially banknotes.

DE 198 09 085 discloses a security structure comprising filaments.

US 4,462,866 and FR 2,117,055 disclose a knitted band.

FR 2,114,705 discloses a knitting yarn in a thermoplastic material and melted in situ so as to mix locally with the fibrous material of the paper.

The present invention aims in particular to meet at least one of the aforementioned needs.

According to one of its aspects, the invention relates to a sheet material according to claim 1.

The expression "sheet material" may denote in the description and the claims a sheet of paper and / or plastic, having a monolayer or multilayer structure, composite or not. A sheet material may for example have a relatively small thickness, especially less than or equal to 3 mm, for example equal to about 100 microns, and be flexible. In an exemplary implementation of the invention, the sheet material may be packaged in a reel, in particular before being cut into the desired format.

The invention offers many advantages.

Firstly, the knitted structure can allow, if desired, depending for example on its positioning, its nature and its size, to mechanically reinforce the sheet material, and in particular to reduce the risk of tearing of the sheet material. this. This can be useful in particular to improve the mechanical strength of banknotes, for example. The fact that the structure is knitted allows to achieve it if desired with relatively wide meshes, which can facilitate its incorporation into a paper mass.

Furthermore, the structure being knitted, it may have a certain elongation in at least one direction, which may make it easier to incorporate in a paper, for example. It is possible to give the knitted structure, for example by choosing the mesh pattern, the elongation that is desired, in particular to allow the incorporation of the structure within a fibrous layer during its manufacture on a paper machine. The elongation presented by the knitted structure will advantageously be sufficient to avoid the appearance of internal stresses likely to damage the fibrous layer or the knitted structure itself, especially during drying of the paper. The elongation may be, before incorporation of the structure into the sheet material, for example between about 1% and about 5%, especially at least about 1%, 2%, 3%, 4% or 5%. %, in a predetermined direction of elongation. When the knitted structure is in the form of a strip, the aforementioned elongation direction is advantageously parallel to the longitudinal direction of the strip, which may correspond to the direction of travel of the knitted structure in the paper machine. The knitted structure can be made, if desired, so as to be able to extend in two different directions, in particular two directions perpendicular to each other. For example, the elongation of the knitted structure may be at least 3% in a first direction and at least 1% in a second direction, perpendicular to the first, before incorporation of the knitted structure into the sheet material. .

In addition, thanks to the invention, it is possible, where appropriate, to incorporate into the structure a large variety of son, having or not intrinsically the necessary stretchability, while ensuring that the structure has the elongation overall desired.

Advantageously, the structure is knitted with at least five threads, in particular at least ten threads, for example about twenty threads.

The knitted structure may comprise for example at least one metal wire or a metal alloy, for example steel or Permalloy type alloy for antitheft detection. The structure may also, where appropriate, incorporate at least one wire used for authentication.

The knitted structure can be made with various mesh shapes, which may allow for example to create specific patterns, which may contribute to make it more difficult to falsify and / or serve for the identification of a document or at the level of visual aspect, either to the touch, for example by the visually impaired.

The knitted structure may also be made with a variable shape, for example a band having a non-constant width, which makes it possible to increase the aesthetic possibilities, identification and / or authentication, for example in combination with other authentication elements superimposed at least partially on the knitted structure or integrated therewith.

The knitted structure may have a mechanical reinforcement function and an authentication and / or identification function.

The knitted structure may comprise one or more son made of plastic, in particular polyamide, acrylic or polyester, based on mineral fibers, for example glass or carbon, or based on plant material (s) or animal (s).

All the son of the structure may for example be plastic, except one which is metallic. The higher the number of different wires, the more difficult the structure can be to reproduce and therefore to counterfeit.

The knitted structure may be at least partially plain knit, knit 1/1 rib, English rib, half-English rib, variure, guilloche knit, knit "8 locks", interlock, knit-fabric, knit jacquard, knit returned, this list not being limiting.

In an exemplary implementation of the invention, the knitted structure is configured to create on at least one outer face of the sheet material, in particular on two outer faces of the sheet material, a visually perceptible and / or tactile texture.

In order to improve the authentication and / or the identification of a document, the structure may comprise at least one authentication and / or identification element chosen for example from: an element for highlighting a falsification , in particular visible and / or detectable by means of a specific detection device, an element with variable and / or diffractive, interferential, iridescent or liquid crystal optical effect, a magnetic or crystalline coating, magnetic fibers, tracers detectable tracers by X-ray fluorescence, biomarkers, a varnish or an ink, luminescent or fluorescent tracers, photochromic, thermochromic, electroluminescent and / or piezochromic compounds and / or which change color in contact with a or several predetermined products.

In an exemplary implementation of the invention, the authentication element and / or identification is carried by at least one wire of the knitted structure.

The structure may comprise at least one of the following yarns, in particular a combination thereof: a fluorescent or phosphorescent yarn, a magnetic yarn having soft or hard magnetism properties, a yarn allowing detection by exposure to microorganisms, waves. The multiplication of wires with different properties may enhance safety.

As the authentication element (s) and / or identification element (s) can be incorporated on the yarns of the knitted structure, the invention makes it possible, if necessary, to provide a better rendering, in particular a visual one, and to obtain a more homogeneous effect. stable, especially in the case where the authentication and / or identification elements, for example fibers or markers, would be dispersed in the mass of the fibrous layer.

In an exemplary implementation of the invention, the knitted structure is made with metal wires having soft magnetism properties, for example of the type described with reference to the patent application. EP 897 569 . This knitted structure may, if desired, have a strip shape with a width less than or equal to 1 cm, the son each having a diameter of, for example, between 20 μm and 30 μm.

The incorporation of this strip-knitted structure into the sheet material makes it possible to obtain a strip-like zone on this material which is well defined, contrary in particular to a strip zone formed by incorporating fibers cut into the mass of the sheet material. .

The knitted structure may comprise a combination of metal son having soft magnetism properties and one or more son, metal or not, of different nature, especially with different magnetic properties.

The knitted structure may comprise any type of yarn, for example a flattened yarn, a yarn having a star-shaped section, a textured yarn, a twisted yarn, a single-stranded or multi-stranded yarn, for example a double yarn.

One of the son of the structure may be composite, that is to say comprise at least two different materials, for example a core in a first material and a sheath in a second material. At least one yarn of the structure may in particular comprise a coating comprising an interferential multilayer, providing an effect of color, this coating comprising for example a succession of layers of high and low refractive indices.

The knitted structure may comprise at least two yarns of different colors. The colors of the wires of the structure can thus be used for authentication and / or identification. Alternatively, all the son of the structure have the same color.

In an exemplary implementation of the invention, the son of the structure, for example in a transverse direction when the structure is in the form of a band, intersections forming a detectable code, possibly by a device of specific detection, especially optical.

In an exemplary implementation of the invention, the structure is knitted so as to have at least one pattern, including a drawing, a logo or a text. The pattern, design, logo or text may, where appropriate, be repeated at regular intervals along the structure.

The structure can be knitted, if necessary, by changing the type of mesh being knitted.

The knitted structure may have a thickness less than or equal to 100 μm, in particular less than 70 μm, for example less than or equal to 50 μm, and have for example a strip shape, with in particular a width of less than 50 mm, in particular less than 20 mm, for example between 5 and 30 mm, for example between 5 and 15 mm, or between 10 and 20 mm, when it must be used as a "safety band". The knitted structure can still extend over the entire width of the sheet material, especially when the knitted structure is to strengthen it.

The thickness of the sheet material may be greater than that of the structure.

In an exemplary implementation of the invention, when the nature of the son used allows it, the structure is heat-fixed at least partially, especially hot calendering, to improve its dimensional stability and / or reduce its thickness. During heat-setting, the crisscrossing of yarns can in particular undergo a fusion which solidarises the son between them.

The knitted structure may comprise a coating which covers it at least partially. This may comprise for example an adhesive for improving the anchoring of the structure within the sheet material, for example a heat-sealable varnish. The coating may further comprise, if desired, particles, for example for example, magnetic particles or pigments, for example iridescent pigments. The coating may also include an interferential multilayer structure, producing a color effect observed through a window of the sheet material for example.

In an exemplary implementation of the invention, the coating comprises a metal, for example aluminum or copper. The knitted structure may also be at least partially coated with an ink, in particular an ink deposited by printing. The ink may contain at least one luminescent, fluorescent, photochromic, thermochromic, electroluminescent and / or piezochromic compound.

The knitted structure may be at least partially embedded in a layer of the sheet material, this layer being especially non-textile. This layer may for example be fibrous in nature, and contain paper fibers, for example cellulosic and / or fibers of synthetic nature.

When the knitted structure is embedded at least partially in a fibrous layer, it advantageously has meshes with a size chosen to allow the penetration of fibers through these meshes, so as to ensure a satisfactory cohesion of the fibrous layer and a good anchoring of the structure within the fibrous layer.

The meshes of the structure may form, for example, voids having an area of at least 0.1 mm ² , in particular at least 1 mm ² , for example at least 5 mm ² , for example at least about 9 mm ² or 16 mm ² or more, when the structure is flat and seen from above.

In an exemplary implementation of the invention, the knitted structure comprises at least one portion embedded in at least one layer of sheet material and at least one uncovered portion, for example a succession of portions alternately embedded and discovered. The knitted structure may, alternatively, be entirely embedded in the sheet material or come along its entire length flush with an outer face thereof.

In an exemplary implementation of the invention, the knitted structure has a width less than that of the sheet material. Alternatively, the knitted structure may extend over the entire extent of the sheet material, on its surface or not. The structure can in particular extending from a first edge of the sheet material to a second edge, opposite the first.

The invention also relates to a document, in particular security and / or value, comprising and / or constituted by a sheet material as defined above.

The document can be chosen from: a bank note, an identity document such as an identity card, a driver's license or a pass, a passport slip or cover, a visa, a coupon, a valuable document other than a bank note, for example a check or a credit card, a protection and / or authentication label, a traceability label, an entry ticket for a cultural or sports event.

The invention also relates to a printing medium comprising and / or constituted by a sheet material as mentioned above.

This printing medium can be constituted for example by a letter paper, a paper for a printer, an envelope, a cardboard paper, this list not being limiting.

The invention further relates, in another of its aspects, independently or in combination with the above, to a knitted structure intended to be incorporated at least partially in a sheet material, the knitted structure comprising at least one element of authentication and / or identification.

The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a sheet material, characterized in that it comprises at least one knitted structure comprising at least two son having sizes and / or different optical, physical or chemical forms and / or properties, the knitted structure having, prior to incorporation into the sheet material, an elongation of at least about 3% in a predetermined direction.

The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a sheet material, characterized in that it incorporates at least one knitted structure made with at least two mesh shapes different.

The invention further relates, in another of its aspects, independently or in combination with the foregoing, a sheet material, characterized in that it incorporates at least one knitted structure extending over the entire surface of the sheet material, the structure being knitted so as to form at least one pattern, this pattern having for example the appearance of a strip extending from a first edge of the sheet material to a second edge opposite the first edge.

The invention further relates, in another of its aspects, a sheet material having a substantially rectangular shape, characterized in that it incorporates at least one knitted structure extending along one side of the rectangle.

Advantageously, the sheet material incorporates two knitted structures disposed respectively along two parallel sides of the rectangle.

The invention thus makes it possible to reinforce, as the case may be, two or four corners of the sheet material.

The invention further relates, in another of its aspects, independently or in combination with the foregoing, a sheet material comprising at least one intertwined son structure, in particular knitted, the structure having a width less than that of the material in sheet. Such a structure can be configured for example to create on at least one face of the sheet material, in particular on two sides, a visually perceptible and / or tactile texture and possibly comprise at least one authentication and / or identification element .

The invention further relates, in another aspect, a sheet material having a crisscrossed son structure, in particular knitted, at least partially embedded in at least one layer, in particular a fibrous layer, sheet material. Such a structure advantageously has meshes having a size large enough to allow penetration of fibers through the structure. The meshes may form, for example, voids having an area of at least 0.1 mm ² , in particular at least 1 mm ² , for example at least 5 mm ² , for example at least 9 mm ² approximately or about 16 mm ² , when the structure is observed flat from above. The structure may extend over substantially the entire extent of the sheet material, or alternatively only in a fold zone of the sheet material, especially in a middle region thereof.

In an exemplary implementation of the invention, the structure extends along at least one edge of the sheet material. This can incorporate a single knitted structure or, alternatively, at least two knitted structures, for example a first knitted structure in a middle zone and second and third knitted structures substantially parallel to the first and extending along two opposite edges of the sheet material. In the case of a bank note, this can for example strengthen the corners.

• former au moins une couche fibreuse par une technique papetière, par exemple par dépôt de fibres sur une surface immergée dans une dispersion de matière fibreuse,
• amener une structure tricotée au contact de la couche fibreuse en formation et former éventuellement au moins une fenêtre, traversante ou non, dans laquelle apparaît la structure tricotée,
  ou
• former un premier jet de papier par dépôt de fibres sur une première surface immergée dans une dispersion de matière fibreuse,
• former un deuxième jet de papier par dépôt de fibres sur une deuxième surface immergée dans une dispersion de matière fibreuse,
• amener la structure entre les premier et deuxième jets de papier,
• assembler les premier et deuxième jets de papier de manière à prendre en sandwich la structure tricotée, l'un au moins des jets de papier pouvant comporter une ou plusieurs zones d'épaisseur nulle, chacune étant éventuellement en alternance ou en regard d'une zone d'épaisseur nulle de l'autre jet, la structure tricotée apparaissant à travers ce ou ces zones d'épaisseur nulle.

The invention further relates, in another of its aspects, to a method of manufacturing a sheet material as defined above, comprising the following steps:

• forming at least one fibrous layer by a papermaking technique, for example by deposition of fibers on a surface immersed in a dispersion of fibrous material,
• bringing a knitted structure into contact with the fibrous layer in formation and possibly forming at least one window, through or not, in which the knitted structure appears,
  or
• forming a first paper jet by depositing fibers on a first surface immersed in a dispersion of fibrous material,
• forming a second paper jet by deposition of fibers on a second surface immersed in a dispersion of fibrous material,
• bring the structure between the first and second jets of paper,
• assembling the first and second jets of paper so as to sandwich the knitted structure, at least one of the paper jets may comprise one or more areas of zero thickness, each optionally alternating or facing an area of zero thickness of the other jet, the knitted structure appearing through this or these areas of zero thickness.

• tricoter une nappe ayant une largeur supérieure à celle de la structure,
• découper la nappe pour former la structure, la découpe étant notamment réalisée par ultrasons.

Another aspect of the invention is a method of manufacturing a knitted structure for incorporation into a sheet material, the method comprising the steps of:

• knit a sheet having a width greater than that of the structure,
• cutting the web to form the structure, the cutting being in particular carried out by ultrasound.

Alternatively, the structure is knitted with its final width, which makes it possible not to make cuts after knitting.

The structure may be subjected to heat treatment, in particular heat-setting, for example hot calendering, before incorporation into the sheet material.

In an exemplary implementation of the invention, a coating is deposited on the already knitted structure, in particular after optional thermofixation. Alternatively or additionally, a coating is deposited on at least one of the son of the structure, before knitting. The coating may be an ink deposited in particular by printing.

• acquérir au moins une information caractéristique du maillage de la structure tricotée, par exemple le type de maille, la taille des mailles ou la disposition de celles-ci,
• vérifier l'authenticité et/ou l'identité du document à partir au moins de ladite information,
  ou comportant une étape d'analyse d'au moins un fil de la structure tricotée. L'analyse peut par exemple être une analyse optique, chimique, mécanique, voire une analyse des propriétés biologiques, électriques ou électromagnétiques d'au moins un fil.

The subject of the invention is, in another of its aspects, a method for authenticating and / or identifying a security and / or value document comprising a sheet material as defined above, the process comprising the following steps:

• acquiring at least one characteristic information of the mesh of the knitted structure, for example the type of mesh, the size of the stitches or the arrangement thereof,
• verify the authenticity and / or identity of the document from at least said information,
  or comprising a step of analyzing at least one yarn of the knitted structure. The analysis may for example be an optical, chemical or mechanical analysis, or even an analysis of the biological, electrical or electromagnetic properties of at least one wire.

It is for example possible to provide in two different documents, for example two different denominations of banknotes, knitted structures having different meshes, to distinguish the two cuts.

When the yarns of the knitted structure form a crisscrossing code, authentication and / or identification of the document can be performed by determining the corresponding code.

• la figure 1 représente, schématiquement et partiellement, un exemple de document réalisé conformément à l'invention,
• la figure 2 représente isolément, schématiquement et partiellement, en vue de dessus, la structure incorporée dans le document de la figure 1,
• la figure 3 représente, schématiquement et partiellement, une structure tricotée, présentant des motifs,
• les figures 4 à 6 représentent, schématiquement et partiellement, en coupe transversale, des documents conformes respectivement à d'autres exemples de mise en oeuvre de l'invention,
• les figures 7 à 9 illustrent, schématiquement et partiellement, l'entrecroisement des mailles de différentes structures tricotées,
• la figure 10 représente, schématiquement et partiellement, un détail d'une structure tissée,
• les figures 11 à 13 représentent, schématiquement et partiellement, deux documents conformes à d'autres exemples de mise en oeuvre de l'invention,
• la figure 14 illustre schématiquement une étape d'un procédé de fabrication du document de la figure 1, selon un exemple de mise en oeuvre de l'invention,
• la figure 15 illustre schématiquement une étape d'un procédé de fabrication d'un document selon un autre exemple de mise en oeuvre de l'invention, et
• les figures 16 à 21 représentent schématiquement des documents conformes à d'autres exemples de mise en oeuvre de l'invention.

The invention will be better understood on reading the following detailed description, non-limiting examples of implementation thereof, and on examining the appended drawing, in which:

• the figure 1 represents, schematically and partially, an example of a document produced according to the invention,
• the figure 2 represents in isolation, schematically and partially, in a view from above, the structure incorporated in the document of the figure 1 ,
• the figure 3 represents, schematically and partially, a knitted structure, having patterns,
• the Figures 4 to 6 represent, schematically and partially, in cross-section, documents corresponding respectively to other examples of implementation of the invention,
• the Figures 7 to 9 illustrate, schematically and partially, the intercrossing of the stitches of different knitted structures,
• the figure 10 represents, schematically and partially, a detail of a woven structure,
• the Figures 11 to 13 represent, schematically and partially, two documents in accordance with other examples of implementation of the invention,
• the figure 14 schematically illustrates a step of a method of manufacturing the document of the figure 1 according to an exemplary implementation of the invention,
• the figure 15 schematically illustrates a step of a method of manufacturing a document according to another example of implementation of the invention, and
• the Figures 16 to 21 schematically represent documents in accordance with other examples of implementation of the invention.

In the drawing, for the sake of clarity, the relative proportions of the various elements represented have not always been respected, the views being schematic.

We have shown on the figure 1 a document 1 forming a sheet material within the meaning of the invention, for example a banknote, comprising a fibrous layer 2, in which is incorporated a knitted structure 3 according to the invention.

Document 1 may still be a security document such as an identity document, a passport, a visa, a coupon, a valuable document other than a bank note, a trademark counterfeit protection label or a traceability label.

As illustrated on the figure 2 , the knitted structure 3 may be in the form of a longitudinal axis band X, with a width less than that of the document 1, being for example about 15 mm or less.

Whatever the nature of the sheet material in which it is incorporated, the structure 3 can be knitted in different ways. This may for example be a plain knit, being knitted on a bed only of a knitting machine.

Alternatively, the structure 3 may be a ribbed knit formed on two needle straps simultaneously of a knitting machine.

Among the various types of ribbed knits, there may be mentioned by way of example a single-sided knit knit 1/1.

The ribbed knit can still be a knitted mesh knit, also called knit knit.

We have shown on the figure 7 a crisscross pattern of double-stitched double-stitch knits.

The ribbed knit can also be a half-English knit rib with 1/1 rib rows alternating with rows of English ribs.

The structure 3 may alternatively be knitted to form a variure or a guilloche knit.

In another embodiment of the invention, the structure 3 forms a knit "8 locks", for example an interlock knit, making it possible to produce the structure 3 with stripe or checkerboard patterns.

The structure 3 may also be formed by a knit-fabric having a mixture of rows in rib and rows in plain.

To produce the structure 3 with patterns 9, for example star patterns, as illustrated in FIG. figure 3 the structure 3 can be knitted according to an intersia knit or a jacquard knit.

The structure 3 can still be knitted in stitches, as illustrated on the figure 9 .

Of course, the invention is not limited to the examples of knits mentioned above, and other cross-threaded structures may still be suitable.

For knitting techniques, we can refer to the book "DUBIEB Knitting Course", Edouard DUBIEB, Neufchatel, SWITZERLAND.

The knitted structure 3 may have before its incorporation in the document 1 an elongation along the X axis of at least about 3% for example. The number of constituent yarns of the knitted structure 3 may depend, for example, on patterns or elements identification or authentication that you want to integrate. The knitted structure 3 may comprise for example at least five threads, especially at least ten threads, for example about twenty threads.

The structure 3 can be knitted with its definitive width, so that it is not necessary to reduce its width before incorporation into the fibrous layer. As a variant, the final structure 3 is obtained by cutting, in particular by ultrasound, a knitted sheet having a width greater than the definitive width of the structure 3.

In order to improve the dimensional stability and / or to reduce its thickness, the knitted structure 3 may be subjected to a heat treatment, for example to be hot heat-set by calendering, in particular when the yarns used are made of thermoplastic material.

The structure 3 may be coated, if necessary, with an adhesive, for example a heat-sealable varnish.

The structure 3 can be knitted from yarns of the same nature as illustrated in FIG. figure 7 or, alternatively, from several son of different natures, for example to multiply the securities.

• un fil en matière plastique, notamment en polyamide, en acrylique ou en polyester,
• un fil métallique, notamment en acier,
• un fil à base de fibres de verre ou de carbone,
• un fil à base de matière végétale ou animale.

The structure 3 comprises for example at least one of the following son:

• a plastic yarn, in particular made of polyamide, acrylic or polyester,
• a wire, especially of steel,
• a fiber-glass or carbon-based yarn,
• a yarn based on vegetable or animal matter.

As illustrated on the figure 8 the structure 3 may comprise only polyamide yarns 10, with the exception of a wire 11 made of steel, for example, in particular of a Permalloy type material, which may allow detection by certain anti-theft gates.

In the examples illustrated in Figures 7 and 8 , the rows of meshes are substantially parallel to the axis X.

The structure 3 may comprise son having all the same color or alternatively comprise at least two son of different colors.

Depending on the desired level of security, the structure 3 may comprise at least one fluorescent or phosphorescent wire, a magnetic wire having properties of soft or hard magnetism and wire compatible with microwave detection.

The knitted structure 3 may be made for example from 19 polyester yarns and a fluorescent yarn, each yarn having for example a diameter of about 33 μm and the knitted structure a thickness substantially double of said diameter, that is to say close to 66 μm.

It is possible to incorporate in the structure 3, on demand, at least one authentication and / or identification element chosen from one of the following elements: a highlighting element of a falsification, in particular visible and / or detectable by means of a specific detection device, an element with variable and / or diffractive optical effect, iridescent or liquid crystal, a magnetic or crystalline coating, magnetic fibers, tracers detectable by magnetic resonance, detectable tracers by X-ray fluorescence, biomarkers, a varnish or an ink, luminescent or fluorescent tracers, photochromic, thermochromic, electroluminescent and / or piezochromic compounds and / or which change color in contact with one or more predetermined products .

The aforementioned authentication and / or identification element may be incorporated in a coating deposited on the knitted structure 3, for example by coating or printing.

The knitted structure 3 can be made in such a way that it is possible to authenticate and / or identify a document from a mesh parameter of the structure 3 and / or by detection of an authentication element and / or identification present on the structure 3.

The knitted structure 3 can be completely embedded in the fibrous layer 2, as can be seen on the figure 4 .

Alternatively, as illustrated on the figure 5 , the structure 3 comes at least partially flush with a face 4 of the document 1, for example to create a detectable relief to the touch or to visually observe the structure 3, for example to see the mesh or coating of surface deposited on at least one wire thereof. In another variant, as illustrated on the figures 6 and 16 , the structure 3 is partially embedded in the fibrous layer 2 so as to present alternately embedded and uncovered portions. For this purpose, the fibrous layer 2 may comprise zones 8 such as recesses forming windows leaving portions of the structure 3 discovered. The fibrous layer 2 may comprise, if appropriate, bosses 9, shown in dotted lines on the figure 6 located between zones 8.

The meshes chosen can be used to authenticate and / or identify a document, in particular because of the texture created. For example, a first denomination of bank notes may comprise a knitted structure having a first stitch pattern, for example English-side, as illustrated in FIG. figure 7 , and a second cut comprises a structure with a second stitch pattern, different from the first, for example with rolled ribs, as illustrated on the figure 9 .

The wires of the structure 3 may furthermore have intercrossings whose arrangement forms a detectable code by means of a specific detection device, for example optical.

The structure 3, once incorporated in the fibrous layer 2, can create on at least one outer face 4 of the document 1, in particular on two sides, an area 7 having a texture detectable visually and / or to the touch, as illustrated in FIG. figure 4 .

The texture in the zone 7 may be more or less pronounced depending on the thickness of the structure 3. The structure 3 may have, for example, a thickness of less than 50 μm, in particular between about 30 μm and 40 μm, for a thickness total of the upper sheet material for example.

The structure 3 can still be used only to improve the mechanical strength of the fibrous layer 2 and do not comprise any specific authentication and / or identification element, in which case the structure 3 preferably extends over the entire length of the structure. 1, and if necessary without inducing detectable relief to the touch on the surface of the sheet material.

In the examples which have just been described, the structure 3 is knitted. According to other aspects of the present invention, the structure 3 may be replaced by a structure 3 'which is woven, as shown in FIG. figure 10 . The woven structure 3 'may or may not include authentication and / or identification elements, being made from son of different natures or not.

In the example of the figure 1 , the structure 3 extends over a relatively small width, between two opposite edges 15 of the document 1.

Alternatively, the structure 3 or 3 'may extend over a larger width, as illustrated in FIG. figure 11 , so as to cover in particular a folding zone of the document 1. In the example of a banknote, the folding zone may be in a central zone.

In another variant, the structure 3 or 3 'may extend over the entire surface of the document 1, as illustrated in FIG. figure 12 , in order to mechanically strengthen the document over its entire surface.

A sheet material according to the invention may comprise a number of structures 3 or 3 'greater than or equal to two. As illustrated on the figure 13 document 1 may comprise three structures 3 or 3 ', a first extending in a median zone and the other two along two opposite edges of the document 1. The two structures located at the edge may for example each correspond to half a larger structure cut in half when cutting the document 1 to its final format.

Structure 3 or 3 'can be incorporated in various ways into the sheet material.

We have shown, partially and schematically, on the figure 14 , a paper machine with round shape. This machine comprises a tank 15 containing a suspension 16 of fibers, for example of cellulose fibers and / or cotton linters and / or synthetic and / or artificial fibers, in which is partially immersed a rotating cylinder 17 defining a surface 18 in contact with which is formed continuously the fibrous layer 2.

It is possible to incorporate in the fibrous layer 2, during its formation, the knitted structure 3 or woven 3 '. When the fibrous layer 2 has bosses 9 as described above, the cylinder 17 may comprise reliefs 13, shown in dotted lines on the figure 14 these reliefs 13 being constituted for example by bosses on the cylinder 17 or by one or more masks.

We illustrated on the figure 15 a method for incorporating a knitted or woven structure into a sheet material according to another embodiment of the invention.

In this process, a first paper stream 20 is formed in contact with a first surface 21 of a cylinder 22 immersed in a fibrous dispersion.

The first jet 20 is driven towards a second cylinder 24 immersed in a second fibrous dispersion, a second paper jet 20 being formed in contact with a surface 25 of the second cylinder 24. A knitted structure 3 or woven 3 ' is fed between the first and second jets of paper between the cylinder 24 and a drive cylinder 27 so as to allow the incorporation of the structure within the two jets of paper.

Of course, the invention is not limited to the implementation examples which have just been described.

The structure 3 or 3 'may for example be embedded in the fibrous layer 2 without creating texture on the surface of the sheet material.

The structure 3 may be knitted so as to form on a portion of its surface a pattern 40, for example a pattern having the appearance of a strip, as illustrated in FIG. figure 17 .

In the example considered, the structure 3 extends over the entire surface of the document 1. In a variant, the structure 3 extends over only a portion of the surface of the document.

The thread or yarns for knitting the pattern 40 may be of a nature and / or aspect, for example of color, different from the thread or yarns used to knit the parts of the structure 3 outside the pattern 40.

The pattern 40 may for example be knitted according to a mesh different from that of the parts of the structure 3 outside the pattern 40.

As illustrated on Figures 18 and 19 , the document 1, in particular of rectangular shape, may comprise a striped knitted structure 3 extending along a long side of the rectangle ( figure 18 ) or a small side ( figure 19 ).

In a variant illustrated in Figures 20 and 21 document 1 comprises two striped knitted structures 3 extending respectively along the two long sides of the rectangle ( figure 20 ) or two short sides of the rectangle ( figure 21 ).

Throughout the description, including the claims, the phrase "having one" should be understood as being synonymous with the phrase "having at least one", unless the contrary is specified.

Claims (40)

1. A sheet material (2), characterized by the fact that it incorporates at least one knitted structure (3), the knitted structure (3) including at least two threads (10; 11) made of different materials.
2. A material according to claim 1, characterized by the fact that the knitted structure (3) presents, prior to being incorporated in the sheet material, elongation lying in the range about 1% to about 5%, and in particular of at least about 2%, 3%, 4%, or 5% in a predetermined direction.
3. A material according to the preceding claim, the knitted structure being in the form of a strip, the material being characterized by the fact that said elongation direction is substantially parallel to the longitudinal direction (X) of the structure (3).
4. A material according to any one of the preceding claims, characterized by the fact that the structure comprises at least one thread of plastics material, in particular of polyamide, acrylic, or polyester.
5. A material according to any one of the preceding claims, characterized by the fact that the structure includes at least one metal or alloy wire.
6. A material according to any one of the preceding claims characterized by the fact that the knit is of one of the following types: plain; 1/1 ribbed; full cardigan ribbed; half-cardigan ribbed; rib lace; knit-and-tuck; eightlock; interlock; knit weave; jacquard; purl.
7. A material according to any one of the preceding claims, characterized by the fact that the structure is configured to create a texture that can be perceived visually and/or by touch on at least one outside face of the sheet material, and in particular on both outside faces of the sheet material.
8. A material according to any one of the preceding claims, characterized by the fact that the structure includes at least one authentication and/or identification element.
9. A material according to the preceding claim, characterized by the fact that the authentication and/or identification element includes at least one of the following elements: an element for revealing falsification, in particular an element that is visible and/or detectable with the help of a specific detection device; an element presenting an optical effect that is variable and/or diffractive, iridescent, or using liquid crystals; a coating that is magnetic or crystalline; magnetic fibers; tracers detectable by magnetic resonance; tracers detectable by X-ray fluorescence; biomarkers; a varnish or an ink; luminescent or fluorescent tracers; compounds that are photochromic, thermochromic, electroluminescent, and/or piezochromic, and/or that change color on coming into contact with one or more determined substances.
10. A material according to claim 8 or claim 9, characterized by the fact that the authentication and/or identification element is carried by at least one thread of the knitted structure.
11. A material according to any one of claims 8 to 10, characterized by the fact that the structure includes at least one fluorescent or phosphorescent thread.
12. A material according to any one of claims 8 to 11, characterized by the fact that the structure includes at least one magnetic thread, in particular a thread presenting properties of soft magnetism.
13. A material according to any one of the preceding claims, characterize by the fact that the structure is knitted in such a manner as to present at least one pattern, in particular a design, a logo, or a text.
14. A material according to any one of the preceding claims, characterized by the fact that the structure is knitted with at least five threads, and in particular with at least ten threads.
15. A material according to any one of the preceding claims, characterized by the fact that the knitted structure presents thickness that is less or equal to the thickness of the sheet material, in particular thickness that is less than or equal to 100 µm approximately, in particular less than 70 µm, e.g. less than or equal to 50 µm approximately.
16. A material according to any one of the preceding claims, characterized by the fact that the structure is in the form of a strip.
17. A material according to the preceding claim, characterized by the fact that the structure presents a width of less than 50 mm, in particular a width lying in the range 5 mm to 30 mm, for example in the range 5 mm to 15 mm or in the range 10 mm to 20 mm
18. A material according to any one of the preceding claims, characterized by the fact that the structure is thermofixed, at least in part.
19. A material according to any one of the preceding claims, characterized by the fact that the knitted structure includes a coating covering it at least in part.
20. A material according to the preceding claim, characterized by the fact that the coating comprises an adhesive, in particular a heat-sealable varnish.
21. A material according to claim 19, characterized by the fact that the coating includes particles, in particular magnetic particles, or pigments.
22. A material according to claim 19, characterized by the fact that the knitted structure includes an ink, in particular an ink deposited by printing.
23. A material according to claim 19, characterized by the fact that the coating contains at least one compound that is luminescent, fluorescent, photochromic, thermochromic, electroluminescent, and/or piezochromic.
24. A material according to the preceding claim, characterized by the fact that the knitted structure (3) is embedded at least in part in a fiber layer (2) of the sheet material, the knitted structure presenting stitches of a size that is sufficiently large to allow the fibers to penetrate through the stitches.
25. A material according to the preceding claim, characterized by the fact that the stitches of the structure form voids having an area of at least 0.1 mm², in particular at least 1 mm², better at least 5 mm², in particular at least about 9 mm² or 16 mm² when the structure is flat and observed from above.
26. A material according to claim 24 or claim 25, characterized by the fact that the structure (3) includes at least one covered portion embedded in at least one layer of sheet material and at least one uncovered portion, in particular an alternating succession of covered and uncovered portions.
27. A material according to claim 1, characterized by the fact that the structure is completely embedded in the sheet material.
28. A material according to claim 1, characterized by the fact that the structure is flush with an outside face (4) of the sheet material (2) over its entire length.
29. A material according to any one of the preceding claims, characterized by the fact that the structure (3) presents a width that is narrower than the width of the sheet material (2).
30. A material according to any one of the preceding claims, characterized by the fact that the structure extends from a first edge of the sheet material to a second edge, opposite from the first.
31. A material according to any one of the preceding claims, characterized by the fact that it incorporates a single knitted structure.
32. A material according to any one of claims 1 to 30, characterized by the fact that it incorporates at least two knitted structures.
33. A material according to the preceding claim, characterized by the fact that it incorporates a first knitted structure in a middle zone and second and third knitted structures that are substantially parallel to the first and that extend along two opposite edges of the sheet material.
34. A material according to claim 1, the knitted structure extending in a folding area of the material.
35. A document (1), in particular a security document and/or a document of value, comprising a sheet material (2) as defined in any one of the preceding claims.
36. A document according to the preceding claim, characterized by the fact that it constitutes one of the following elements: a bank note; an identity document such as an identity card, a driving license, or a pass; a leaf or a cover for a passport; a visa; a coupon; a document of value other than a bank note, e.g. a check or a credit card; a label for protection and/or authentication purposes; a traceability label; an entry ticket for a cultural or sporting event.
37. A print medium comprising a sheet material according to any one of claims 1 to 34.
38. A method of manufacturing a sheet material as defined in any one of claims 1 to 34, the method comprising the following steps:

    · forming at least one fiber layer by depositing fibers on a surface immersed in a slurry of fiber material; and

    · bringing a knitted structure into contact with the fiber layer being formed and optionally forming at least one window through which the knitted structure appears; or

    · forming a first ply of paper (20) by depositing fibers on a first surface (21) immersed in a slurry of fiber material;

    · forming a second ply of paper (23) by depositing fibers on a second surface (25) immersed in a slurry of fiber material;

    · bringing a knitted structure between the first and second plies of paper; and

    · assembling together the first and second plies of paper in such a manner as to sandwich the knitted structure, at least one of the plies of paper optionally including one or more zones of zero thickness, each optionally alternating or being in register with a zone of zero thickness in the other ply of paper, the knitted structure being visible through said zone(s) of zero thickness.
39. A method of authenticating and/or identifying a security document and/or a document of value comprising a sheet material as defined in any one of claims 1 to 34, the method comprising the following steps:

    · acquiring at least one item of information characteristic of the knit of the knitted structure; and

    · verifying the authenticity and/or the identity of the document on the basis at least of said item of information;

    or comprising a step of analysis of at least one thread of the structure, in particular by an optical, chemical, and/or mechanical analysis, and/or by an analysis of biological, electrical, or electromagnetic properties of said at least one thread.
40. A method according to the claim 39, the knitted structure comprising a magnetic thread, the verification being performed from the detection of the magnetic thread.

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