EP1931827B1 - Method for producing a sheet of fibrous material comprising localized portions of fibrous material - Google Patents

Abstract

The invention relates to a method for producing a sheet of fibrous material, comprising the step of producing thin elements (5, 10) of fibrous material and of combining the thin elements with one another in order to form a sheet in which one of at least the thin elements (5) is discontinuous and forms isolated portions of fibrous material.

Description

The invention relates to a method of manufacturing a sheet of fibrous material comprising localized contributions of fibrous material.

BACKGROUND OF THE INVENTION

Methods of making a sheet of fibrous material including the step of producing thin elements of fibrous material and associating the thin elements with each other to form the sheet are known. In particular, it is known to produce, with the aid of a first porous round shape, a continuous stream of moist fibrous material forming a first layer, to produce with a second porous round shape a continuous stream of fibrous material. forming a second layer, then applying the second layer on the first layer to form a sheet of increased thickness.

This covers the entire surface of the first layer by the second layer, even if it may have locally holes, as shown in the documents EP 0 625 431 or WO 95/09274 .

OBJECT OF THE INVENTION

The subject of the invention is a process for manufacturing a sheet of fibrous material making it possible to obtain security documents that are different from those known.

BRIEF DESCRIPTION OF THE INVENTION

In order to achieve this object, there is provided a method of making a sheet of fibrous material, comprising the step of producing thin elements of fibrous material and associating the thin elements together to form the sheet, wherein the invention at least one of the thin elements is discontinuous and comprises isolated portions of fibrous material.

Thus, the supply of fibrous material is localized way which allows, by giving the isolated portions a particular characteristic (shape, pattern, location, color, presence of identification elements in the fibrous pulp) which distinguishes them from the rest of the document, to create new security possibilities a fibrous document.

Preferably, one of the thin elements is continuous and forms a layer of fibrous material.

According to a particular embodiment of the method of the invention, the layer is manufactured using a first porous round shape producing a continuous stream of wet fibrous material, the isolated portions are manufactured using at least one second porous round shape producing a discontinuous stream of wet fibrous material, the discontinuous stream and the continuous stream being contacted to associate the insulated portions with the continuous layer.

Thus, the multijet fabrication technique is adapted to implement the method of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 est une vue schématique d'un premier mode de mise en oeuvre du procédé de l'invention au moyen de formes rondes poreuses ;
• la figure 2 est une vue schématique d'un deuxième mode de mise en oeuvre du procédé de l'invention au moyen de formes rondes poreuses ;
• la figure 3 est une vue de face d'un document fibreux obtenu selon le procédé de l'invention et illustrant plusieurs applications du procédé de l'invention ;
• la figure 4 est une vue en coupe dans l'épaisseur d'un document fibreux obtenu selon le procédé de l'invention et illustrant diverses applications du procédé de l'invention ;
• la figure 5 est une vue schématique d'un troisième mode de mise en oeuvre du procédé de l'invention au moyen de formes rondes poreuses, adapté à la production de documents à fenêtres;
• la figure 6 est une vue en coupe partielle au niveau d'une fenêtre d'un document obtenu par le procédé illustré à la figure 5;
• la figure 7 est une vue en coupe dans l'épaisseur d'un document comportant un filigrane obtenu selon un mode particulier de mise en oeuvre du procédé de l'invention.

The invention will be better understood in the light of the description which follows with reference to the figures of the appended drawings in which:

• the figure 1 is a schematic view of a first embodiment of the method of the invention by means of round porous shapes;
• the figure 2 is a schematic view of a second embodiment of the method of the invention by means of round porous shapes;
• the figure 3 is a front view of a fibrous document obtained according to the method of the invention and illustrating several applications of the method of the invention;
• the figure 4 is a sectional view in the thickness of a fibrous document obtained according to the process of the invention and illustrating various applications of the process of the invention;
• the figure 5 is a schematic view of a third embodiment of the method of the invention by means of round porous shapes, adapted to the production of documents with windows;
• the figure 6 is a partial sectional view at a window of a document obtained by the method illustrated in FIG. figure 5 ;
• the figure 7 is a sectional view in the thickness of a document comprising a watermark obtained according to a particular mode of implementation of the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

According to a first embodiment of the method of the invention illustrated in FIG. figure 1 , a first porous round shape 1 made of a rolled wire fabric bathed in a first bath 2 of fibrous material dispersed in an aqueous medium is covered with a mask 3 so that only certain areas 4 isolated from the surface of the web of the porous round form 1 are left uncovered. In practice, the mask 3 can be made by applying resin or adhesive to the wire mesh, or by bringing back on the wire mesh portions of metal foil.

While rotating the first porous round shape 1, there is a depression in the center of the latter so that the bath water passes through the porous round shape in the non-masked areas 4 while the fibers remain blocked by the canvas and agglutinate on unmasked areas 4.

The thickness of fibrous material that coalesces on the fabric in the non-masked zones 4 increases progressively as the porous round shape 1 rotates and gives rise to isolated portions. 5 of wet fibrous material. Thus, a discontinuous stream of wet fibrous material composed of the various insulated portions of moist fibrous material is formed.

The insulated portions 5 are supported by a conveyor 6 comprising here a porous plastic web which extends tangentially from the first porous round shape 1. For this purpose, a suction hood 7 draws the insulated portions 5 of wet fibrous material through the web of the conveyor 6 to force them to adhere thereto at the same time as it partially dries the insulated portions 5.

These are conveyed by the conveyor 6 in tangency of a second porous round shape 8 also made of a wire fabric rolled into a cylinder and bathed in a second bath 9 of fibrous material. The second porous round shape 8 here has no mask so that the fibrous material aggregates by depression over the entire surface of the second porous round shape 8. A continuous jet is thus produced forming a layer 10 of wet fibrous material.

The layer 10 is supported by the conveyor 6 by means of a hood 11 which forces the layer 10 to adhere to the web of the conveyor 6. The layer 10 then covers the insulated portions 5 so that the latter form deposits localized fibrous material that adhere to the layer 10.

During drying, the isolated portions 5 intimately marry with the layer 10 to form a sheet of fibrous material with thick spots located at the isolated portions 5. Once the sheet is dry, it is impossible to separate the isolated portions 5 of the layer 10.

According to a second embodiment of the method of the invention illustrated in FIG. figure 2 a first porous round form 21 is used to generate a continuous stream forming a layer 30 of wet fibrous material, and a second porous round shape 28 partially masked to generate insulated portions 25. The layer 30 is brought in line with the second porous round shape by a conveyor 26 and pressed against it by a suction cylinder 27 so that the insulated portions 25 form localized deposits which adhere to the layer 30.

To the figure 3 are illustrated several examples of use of the method of the invention on the same portion of sheet used to manufacture a bank note 40, the fibrous support 41 is illustrated here before printing. The fibrous support 41 here contains a security tape 50 (for example a metal ribbon) which has been inserted in a manner known per se into the layer of fibrous material forming the fibrous support 41 during the manufacture thereof.

According to a particular aspect of the invention, the fibrous support 41 comprises, first of all, a fibrous material band 42 added to the fibrous support 41 according to the method of the invention.

For this purpose, a porous round shape is used, the mask of which reveals elongated zones extending along generatrices of the porous round shape, so that the porous round shape gives rise to isolated portions of fibrous material in the form of strips. which are reported on the associated continuous layer.

Here, the fibrous solution used to make the web 42 contains identifying elements such as optical effect pigments, which have the effect of varying the color of the web 42 according to the orientation of the incident light. These pigments are symbolized by dots on the figure 3 .

Once the fibrous material has dried, the band 42 is intimately bound to the fibrous support 41 but the pigments The optical effect remains confined in the band 42. It is thus possible to produce a sheet having localized contributions of identification elements, which is not possible in the known processes in which only continuous jets of fibrous material are produced. . The confinement to limited areas of identification elements (such as the aforementioned pigments or other elements such as rare earth) saves these identification elements and thus reduces the cost of manufacturing sheets.

A possible counterfeit of such a banknote consists in printing a band with an ink loaded with identifying elements in place of the portion 42 of fibrous material reported. However, such forgery is very easily detectable because the ink does not have the thickness of the band reported according to the method of the invention. Moreover, the ink is easily removed by abrasion while it is difficult to remove the band 42 which is intimately related to the support 41. In addition, it is particularly difficult to restore by means of a printing touch particular of the fibrous texture of the insert strip according to the invention.

It will be noted that the security pattern constituted by the strip 42 extends along the wide width of the fibrous support 41. It is thus possible, thanks to the method of the invention, to create elongated safety elements perpendicular to the direction of the security ribbons which are introduced into the fibrous supports during the formation thereof.

According to another particular aspect of the invention, there is reported on the fibrous support 41 by means of the method of the invention a series of insulated portions in the form of parallel bars 43 which are made here in the same fibrous solution as that which served to make the layer fibrous support 41.

Some of these bars are selectively removed while the fibrous material is still wet, for example by suction or abrasion (the elimination of some bars is symbolically represented on the figure 3 by the dashed outline of the eliminated bars). It is thus possible to produce a true bar code in excess thickness making it possible to identify the fibrous document.

Alternatively, instead of a bar code, it will be possible to produce a matrix code comprising a matrix of small fibrous squares reported on the fibrous support according to the method of the invention, some of these squares being selectively removed to form a matrix code. two-dimensional.

According to another particular aspect of the invention, it is reported by the method of the invention isolated portions of fibrous material here having a visually identifiable star shape 44, one of the stars intentionally straddling the ribbon security 50.

According to yet another particular aspect of the invention, an insulated portion 45 in the form of a rectangle extending integrally on the surface of the security tape 50, without contact with the fiber of the support 41 has been reported thanks to the method of the invention. In general, the security tape 50 is impregnated with hot melt glue so that the fibrous material of the insulated portion 43 adheres directly to the security tape 50 as it is dried.

A possible counterfeit of these reasons is to bring on the support portions of cut leaves. However, such counterfeiting is difficult to implement and easily identifiable.

According to another possible use of the process of the invention, isolated portions 46 have been reported to corners of the support 41, to strengthen them. According to the invention, it is also possible to relate overthicknesses to the probable fold zones of a bank note or more generally to locally reinforce possible areas of weakness of a document in order to increase the life of the document. Preferably, for these local reinforcements, a fibrous material containing longer, more resistant fibers is used.

It will be noted that certain isolated portions (here the isolated portions reinforcing the corners 46) are overlapped by other isolated portions. In practice, this overlap is obtained by using several closed porous round shapes, the insulated portions of which are reported successively, by means of a single conveyor, on the layer forming the fibrous support.

According to yet another particular use of the process of the invention, isolated portions 47 of fibrous material having thermoexpansible microbeads (represented by dots) are reported on the fibrous support 41. During the drying of the sheet, the microbeads expand and give the sheet, in the area of isolated portions, a particular touch to identify the sheet.

Alternatively, it will be possible to integrate into the fibrous material of these isolated portions silky fibers that give a smoother feel, or even glass microbeads.

These elements imparting areas of the fibrous support a particular touch form tactile identification elements reinforcing the security of the fibrous document. It will also be possible to relate to the edge of the fibrous support isolated portions of fibrous material giving a rough feel to facilitate the handling of the support (for example to facilitate the manual counting of banknotes).

With reference to the figure 4 the method of the invention makes it possible, as it has been indicated, to apply an insulated portion 61 in excess of a continuous layer of fibrous material 60. However, the method of the invention also makes it possible to apply an isolated portion 62 in a hollow 63 of the layer 60, so that the insulated portion 62 comes to fill this hollow. It is thus possible to locally provide a fibrous material distinct from that of the layer, for example a colored fiber material or containing identification elements, without giving rise to an extra thickness. It is also possible to apply an insulated portion 64 to fill a hole 65 of the layer 60. For example, it will be possible for the layer 60 to use a fibrous material with long, thick fibers that is favorable to the strength of the sheet, and for the insulated portion 64 a fibrous material with short and fine fibers for producing particularly fine watermarks.

The method of the invention also makes it possible to manufacture window documents. With reference to the figure 5 a first porous round shape 78 is used to produce a continuous jet forming a layer 80. The first porous round shape 78 has embossings 79 making it possible to make orifices 81 in the continuous layer.

In a manner known per se, a transparent ribbon 82 is introduced into the fibrous bath which wraps around the porous round shape, resting on the embossings 79, the ribbon having a width slightly greater than the width of the embossings 79. By suction , the fibers agglutinate on the porous round shape 80 on both sides of the transparent tape 82 and under the latter, except of course at the embossings. This gives a layer 80 with orifices 81 (corresponding to the embossings) which are entirely covered by the transparent tape 82.

According to the invention, a second porous round shape 71 is partially masked to produce a discontinuous stream which forms insulated frame-shaped portions 75 with a central opening 76. These insulated portions are affixed to the layer 80 so that the opening central 76 is facing one of the orifices 81 of the layer 80.

The result of this operation is visible at figure 6 . The layer 80 comprises an orifice 81 covered by the transparent tape 82. This is covered by an insulated portion 75 in the form of a frame (here half is seen) whose opening 76 is opposite the orifice 81. The insulated portion 75 covers the edge of the transparent ribbon 82 and extends beyond this edge to contact the fibrous material of the diaper 80. The insulated portion 75 adheres to both the clear ribbon (which is coated with glue thermofusible) and the fibrous material of the layer 80, and helps to strengthen the edges of the window thus created. Preferably, a transparent microperforated ribbon is used, which facilitates the aspiration of the layer 80 when it is taken from the porous round shape 78 and allows the evacuation of the water contained in the fibrous material in contact with the transparent ribbon 82. This transparent ribbon can of course itself include security features.

According to yet another aspect of the invention illustrated in figure 7 it is possible to create a watermark of a new type. For this purpose, a fibrous layer 90 is produced in a first fibrous material, the layer having locally variations of thicknesses in a given pattern which form a first portion 91 of the watermark according to the invention. On the layer 90, an isolated portion 92 made in a second fibrous material of a different color from that of the first fibrous material, the insulated portion 92 having variations in thickness in a complementary pattern so as to form a second portion of the watermark according to the invention.

Thus, we manage to form two-color watermarks. We can of course generalize this process by affixing several isolated portions of different colors, to achieve a true polychrome watermark.

The invention is not limited to what has just been described, but on the contrary encompasses any variant within the scope defined by the claims.

Although the implementation of the process of the invention has been illustrated by means of a porous round shape producing a continuous stream forming the layer and a porous round shape producing a discontinuous stream composed of isolated portions which form localized deposits one or more other porous round shapes may be used to produce, for example, an additional continuous layer for sandwiching the localized portions between the two layers, or for applying insulated portions made from a plurality of fibrous materials to a single layer. Localized portions can be applied to both sides of the same layer, by combining the embodiments shown in FIGS. Figures 1 and 2 .

Isolated dot-shaped portions of different colors can also be applied to the same face of a layer to form a polychromatic general pattern.

The isolated portions may have any form imaginable as bands, visually recognizable patterns, letter dots, figures, logos ... The bands formed according to the invention may extend in any direction, parallel to the ribbons safety, perpendicular or oblique to them ...

Although it has been stated that insulated portions of fibrous material are produced by means of a porous round shape, other techniques may be used, such as localized projections of fibrous material on the layer. In this regard, the provision of isolated portions may not be made with moist fibrous material. For example, a layer of fibrous nonwoven material made of dry fibers bonded together by means of a binder may be produced, and isolated portions of dry fibrous material may be deposited using the same binder.

Finally, although it has been stated that a continuous thin layer of fibrous material forming a layer and a discontinuous thin element of fibrous material forming isolated portions is produced, the invention also covers the case where none of the thin elements is continuous. For example, a sheet can be produced from two discontinuous thin elements, each composed of disjointed parallel strips, the strips of one of the thin elements being attached with partial overlap between the strips of the other of the thin elements to form a continuous sheet. . Advantageously be provided bevels on the edges of the strips to allow recovery without extra thickness.

Claims (19)

1. A method of fabricating a sheet of fibrous material, the method comprising the step of producing thin elements (5, 10; 25, 30) of fibrous material and of associating the thin elements with one another so as to form the sheet, the method being characterized in that at least one of the thin elements (5; 25) is discontinuous and forms isolated portions of fibrous material.
2. A method according to claim 1, wherein at least one of the thin elements (10; 30; 40; 60; 80; 90) is continuous and forms a layer of fibrous material.
3. A method according to claim 2, wherein the layer is fabricated with the help of a first porous vat former (8; 21) producing a continuous ply of wet fibrous material, and the isolated portions are fabricated with the help of at least one second porous vat former (1; 28) producing a discontinuous ply of wet fibrous material, the discontinuous ply and the continuous ply being put into contact so as to associate the isolated portions with the layer.
4. A method according to claim 2, wherein the layer (41; 90) is fabricated from a first fibrous material, the isolated portions (42, 46, 47; 92) being fabricated from a second fibrous material distinct from the first fibrous material.
5. A method according to claim 4, wherein the first fibrous material (90) and the second fibrous material (92) have distinct colors.
6. A method according to claim 1, wherein the fibrous material of at least one of the isolated portions (42, 47) contains identification elements for the sheet.
7. A method according to claim 6, wherein the identification elements are optical effect pigments.
8. A method according to claim 5, wherein the identification elements are selected to confer a particular feel on the sheet at the location of the corresponding isolated portion (47).
9. A method according to claim 1, wherein at least two of the isolated portions (42, 47) are fabricated from distinct fibrous materials.
10. A method according to claim 2, wherein at least one of the isolated portions (62) is applied in a recess (63) in the layer (60) in order to fill it in.
11. A method according to claim 2, wherein at least one of the isolated portions (64) is applied in a hole (65) in the layer (60) in order to fill it in.
12. A method according to claim 1, wherein the isolated portions (43) are arranged to form an identification code for the sheet.
13. A method according to claim 12, wherein the isolated portions comprise parallel strips (43) forming a bar code.
14. A method according to claim 1, wherein the isolated portions (46) are applied in zones of weakness or in fold zones of the sheet.
15. A method according to claim 1, wherein one of the thin elements (41) comprises a security ribbon (50), at least one of the isolated portions (44) being applied on said thin element so as to extend across the security ribbon.
16. A method according to claim 1, wherein one of the thin elements (41) comprises a security ribbon (50), at least one of the isolated portions (45) being applied on the security ribbon without coming into contact with the fibrous material of the thin element that includes the security ribbon.
17. A method according to claim 1, wherein one of the thin elements (80) comprises a transparent ribbon (82) covering an orifice (81) in the thin element, an isolated portion (75) having an opening (76) being applied on the transparent ribbon (82) in such a manner that the opening in the isolated portion is in register with the orifice of the thin element including the transparent ribbon.
18. A method according to claim 17, wherein the isolated portion (75) extends beyond an edge of the transparent ribbon (82) to come into contact with the fibrous material of the thin element that includes the transparent ribbon.
19. A method according to claim 1, wherein one of the thin elements (90) includes a zone (91) of varying thickness forming a first portion of a watermark, an isolated portion of varying thickness (92) being applied on the thin element (90) in the location of the zone (91) of varying thickness of the thin element in order to form a second portion of the watermark.

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