OA13086A - Sheet of fibrous material having a security film segment and method of inserting a film segment into a sheet of fibrous material - Google Patents

Abstract

The sheet of fibrous material (1), e.g. paper made from cellulose fibres, containing a plastic film strip (2), has the strip made with perforations of different dimensions that give it a homogeneous porosity. The perforations are filled with the fibres, are between 100 and 1000 mcm in size and 200 to 2000 mcm apart, and can be made in a recognisable pattern, e.g. forming the letters BdF (Banque de France). The plastic strip is metallised over part of its surface, with the perforations extending into the metallised portion, and it can also carry diffractive or holographic images or a chip.

Description

1 013086

The present invention relates to a sheet of fibrous material comprising a segment of plastic film at least partially embedded in the fibrous material, and a method of inserting a segment of plastic film into a fibrous material.

BACKGROUND OF THE INVENTION

For securing documents made from a sheet of fibrous material, it is known to insert into the sheet during its manufacture a thread or a security tape having a different compositionof that of the fibrous material to -realize, at least by transparency, contrast with the entire fibrous material, forming the document. In particular, it is known to introduce a wire or ribbon of plastic material into a paper made from cellulosic fibers suspended in a liquid. In order for the suspended fibers to settle properly on the safety board during the dewatering of the paper, the maximum width of the tape is limited to about 3 mm.

Moreover, in order to increase the security, it is known to make on the security tape ins-scriptions in the form of a metallic or colored deposit, se-.Ion a text or a pattern to ensure authen-tification ribbon and thereby authenticating the document. However, the small width of the security ribbon makes it difficult to read the authentication elements.

In order to increase the width of the security tape while permitting proper insertion of the paper into the paper, it has been proposed in WO03 / 085193 to insert into the paper during its manufacture a segment of the plastic film comprising a zone identification being visible on at least one face of the wall, the segment being perforated outside the identification area to allow fibers to imbibe into the perforations. However, the presence of a zone of identification sufficiently large enough to be visible tends to reduce the porosity. duruban and thus makes it difficult to insert this tape during the manufacture of paper.

OBJECT OF THE INVENTION

An object of the invention is to provide a sheet of fibrous material having a segment of film suitably embedded in the fibrous material independently of the means used for identification. SUMMARY OF THE INVENTION-

With a view to achieving this object, the invention proposes a fibrous material sheet comprising a segment of plastic film comprising perforations distributed over at least a portion of the film covered by the fibrous material, fibers being embedded in at least a portion of the perforations, the film segment having perforations of different quails distributed so that the perforated portion has a substantially homogeneous porosity.

Thus, it is ensured of recovery by a homogeneous layer of fibrous material while allowing authentication by an analysis of the distribution ofperforations.

According to another aspect of the invention, it relates to a method of inserting a film segment of plastic material into a sheet of fibrous material, this method comprising a step of forming at least one fibrous layer on a porous form with from a suspension of fibers suspended in a liquid, and an insertion step in the sheet of fibrous material in progress, of a film segment comprising a series of perforations distributed over at least part of the film segment and having dimensions sufficient to allow fiber interlocking in perforations upon liquid flow through the perforations, the perforated portions having a substantially homogeneous porosity adjacent to the porosity of the po- erous form. Thus, in the perforated areas, the ribbon does not affect the flow rate of the fluid carrying the fibers in suspension so that the film segment overlap in the perforated areas is homogeneously effected.

BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will become apparent upon reading the description which follows with reference to the attached figures, of which: FIG. 1 is a partial enlarged view in section along the line; FIGS. 2 and 3 of a sheet of fibrous material equipped with a film segment according to the invention; FIG. 2 is a sectional view along line II-II of FIG. 1; FIG. section 4 is a view similar to that of Figure 1 illustrating an alternative embodiment of perforations in the film segment, - Figure 5 is a view schematic sectional ofa formation tank of a sheet of fibrous materialaccording to the process of the invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the figures, the sheet of fibrous material 1 according to the invention comprises a film segment, here a ribbon 2, embedded in the fibrous material, except for a window 3.

In the illustrated embodiment, the ribbon 2 is cut from a plastic film 4, for example a transparent polyester film, previously coated on at least one face (here on each side) in zones 5 (only one of which is shown in FIG. 1) with metal layers 6, deposited for example by serigraphy using a screen configured to make a reserve delimiting the window 3 and for producing in the window a metallized pattern 7, reproducing the letters BdF here. . The film 4 and the metal-layers 6 are also perforated outside the window 3 in a series of perforations distributed so that the perforated portion has a substantially homogeneous porosityand preferably at least equal to a porosity of a form used for the realization of the leaf of fibrous material as will be seen further.

In the illustrated embodiment, the film comprises a series of holes 8 having a diameter of approximately 500 μτη spaced a distance of 1000 μτη and regularly distributed except for a part of the window 3 and on the other hand a zone 9 delimited by a mixed line in which a pattern is formed using perfo-rations 10 of smaller diameter and closer to each other, here the letters BdF made according desperforations having a diameter of 150 μτη spaced 300gm. It will be noted in the figure that apart from the pattern made by the perforations 10, the film may also comprise perforations 8 interposed so that the po-rosity of the ribbon is homogeneous in the area 9 without disturbing the recognition of the pattern formed by the perforations10 . In the embodiment of Figure 4 perfo-rations 16 are elongated. Like the perforations 8 or 10, the perforations 16 pass through the film 4 and the metal layers 6. In the illustrated embodiment, the perforations 16 are in the form of rectilinear or curvilinear slits, or have complex shapes allowing both constitute a motive. By way of example, the perfo-ration 16 constituting the central part of the F has a T-shaped shape. In the example illustrated, the perforations 16 have a width 1 equal to 150 μτη and a length L equal to 1500 μm. The incorporation of the ribbon 2 into the sheet of fibrous material is carried out in a manner known per se by using a paper machine comprising a poerous shape 11 comprising sealed pads 12 having the dimensions of the windows 3. The porous form 11 is immersed in a liquid bath 13 comprising fibers in sus-pension so as to produce a first fibrous layer 14 in contact with the porous -Il and a second fibrous layer 15 covering the ribbon 2 with the exception of the locations of the windows 3. Note in this connection that right above the ribbon 2 the liquid passes throughperperforations 8 and 10 and thereby causes fibers that interlock in the perforations and thus perform an anchoring of the ribbon 2 in breuse. Of course, the invention is not limited to the illustrated embodiment and alternative embodiments can be made without departing from the scope of the invention as defined by the claims. . '

In particular, although the invention has been glossed out by providing in the ribbon 2 trans-parent windows 3 not covered by the fibers during the formation of the sheet of paper, it can provide a tape2 perforated on any its surface and completely embedded in the fibrous lamina or visible on the surface of the latter paraffleurement.

Although in the embodiment illustrated in FIG. 1, the perforations are circular and are made in only two dimensions, it is possible to provide patterns using perforations of different shapes and of different dimensions, the size of the perforations being preferably included in FIG. - 6 013086 100 μπι and 1000 μπι and the perforations being spaceda distance preferably between 200 μπι and 2000 μπι so as to allow fiber interlining in the perforations and obtain a porosity equivalent to that of the form 11 while retaining the ribbon 2 sufficient mechanical resistance. In the case of perforations in the form of slots such as perforations 16, the smallest dimension is preferably between 100 μπι and 1000 μπι while the largest dimension is preferably between 1000 μπι and 5000 μm, the per-forages being as previously spaced a distance preferably between -00 μπι and 200 μπι.

Although in the illustrated embodimentperforations 10 have been arranged to achieve a mo-tif directly recognizable by transparency, we can achieve by means of perforations an encoding as described in the patent FR 2 843 0 72 in the name of the Bank of France .

Although the film 1 has been described as a partially transparent metallic plastic film, it can also be colored while being transparent, translucent or opaque or fluorescent, or may have diffractive or holographic images. lographiques. The film may be incorporated into the fibrous sheet in the form of point segments, for example in the form of stamps, where appropriate to provide other security elements such as electronic pens. In the latter case, the stamp carrying an electronic chip is preferably deposited on a first wet fibrous layer after complete formation thereof and before the deposition of a second fibrous layer, the imbrication of fibers in the perforations occurring during the final pressing of the two fibrous layers against each other.

Claims (7)

7 013086 CLAIMS 1. Sheet of fibrous material (1) comprisingasegment of plastic film (2) comprisingperforforations (8, 10) distributed over at least a portion of fiber-covered film portion, fibers being interleaved in at least a portion of the fibrous material per-forations (8, 10), characterized in that the film segment comprises perforations of different sizes re-parts so that the perforated portion has a substantially homogeneous porosity. 2. Sheet of fibrous material according to revendi cation 1, characterized in that a portion (10) per-forages forms a recognizable pattern. 3. Sheet of fibrous material according to revendi cation 1, characterized in that the perforations (8, 10) have a size between 100 gm and 1000 gm and are spaced a distance between 200 μτη and 2000 gm. 4. Sheet of fibrous material according to revendi cation 1, characterized in. the perforations (16) are elongated. 5. sheet of fibrous material according to claim 4, characterized in that the perforations (16) have a minimum dimension of between 100 gm and 1000 gm, and a maximum dimension of between 1000 and 5000 gm, and are spaced apart from one another. distance between 200 gm and 2000 gm. 6. Sheet of fibrous material according to revendi cation 1, characterized in that the film segment (2) has at least one metallized part (5) on at leastone face and in that perforations (8, 10) s' extend into the metallized part (5). 7. A method of inserting a plastic film segment (.2) into a sheet of fibrous material (1), said method comprising a step of forming at least one fibrous layer (14) on a porous form from a bath (13) of fibers suspended in a liquid, and a step of insertion into the sheet of fibrous material in process, of a film segment (2) comprising a series of perforations (8, 10) re-portioned on at least a portion of the film segment and having dimensions sufficient to allow imbrication of fibers in perforations during liquid flow through the perforations, characterized in that the perforated portions have a substantially homogeneous porosity adjacent to the porosity of the poetic form (11).