EP0518740B1 - Safety sheet - Google Patents

Abstract

Security document containing a security thread visible in transmitted light and appearing at the surface of the document in determined places called windows. The thread (P) is opaque and on at least one face has iridescent marks (I) appearing at least partially in at least one of the windows on at least one face of the document. The background colour of the thread is that of the part of the document where it will be introduced. The iridescent marks are preferably present on the thread noncontinuously, preferably at uniform intervals spaced at a distance which is equal to approximately that of the windows. Application to paper for bank notes. <IMAGE>

Description

The invention relates to a printable security sheet for the production of banknotes and other documents of value or security; this sheet containing at least one security element, for example a security thread.

It is known to authenticate in particular banknote papers to incorporate a security thread into it. The safety thread is often made of a transparent polyester thread covered with an aluminum layer or printed.

This wire can be visible in transmitted light and invisible in reflected light, as described in patents EP-A-279,880 and US-A-5,002,636.

High-performance technologies such as color photocopying or other high-resolution printing techniques now make it easy to forge valuable documents or papers. Thus, to counter these counterfeits, documents have been produced which contain a security thread which appears on the surface of the document in certain so-called "window" locations, on at least one side of the document.

Methods for manufacturing such documents are described for example in patents EP-A-59056 and EP-A-229645.

If a metallic wire is incorporated according to these methods, in transmitted light, the wire appears as a dark line on each side of the document; in reflected light, shiny metallic parts are observed in the windows.

Document US-A-5002636 describes a document having a security thread covered with a pigmented layer.

However, it is necessary to make it even more difficult to counterfeit documents containing security wires appearing in windows. In patent application EP-A-400902, a security paper has been described containing a security wire which is present in each window. at least two metal parts which form repeating patterns along the wire and such that these two metal parts are of different colors. This wire is produced in particular by creating non-continuous metal parts on one side of a wire which carries on the other face a continuous layer of a metal of color different from the non-continuous parts.

In patent application EP-A-377 167, a security paper which cannot be reproduced by photocopying has been described by means of a security wire which has, in the windows of the paper, structures deflecting light rays coming from the photocopier.
The deflected rays prevent the reproduction of certain prints carried on the paper because they previously interacted with the photoconductor on the drum of the photocopier at the place where the prints would have been reproduced. On the photocopy, clear areas appear in place of the prints. The structures used to deflect the rays are holograms adapted to the geometry of the photocopier.
This solution uses complicated techniques.

The Applicant has found that a security document, containing a security wire which appears on the surface in windows, can be produced in a simple manner and with greater security by using an opaque security wire and which presents, on at at least one side, iridescent marks which appear at least partially in at least one of the windows on at least one side of the document.

The fact that it has iridescent marks protects the document from reproduction by photocopying and allows it to be authenticated in reflected light by observing the face of the document where there are windows.

The fact that the wire is opaque makes the wire observable in the form of a dark line in transmitted light and thus makes it possible to authenticate the document in transmitted light; iridescence is not observed when looking at the wire in transmitted light.

Preferably the wire will have as background color a color similar to that of the part of the document where the wire will be introduced.

Because the wire has the same color (or a close color) as that of the part of the document containing it, it merges with the document and therefore cannot be reproduced during a photocopy.

The iridescent marks may be present on the wire discontinuously and preferably at regular intervals spaced apart by a pitch equal to approximately that of the windows. Preferably the marks go from one edge to the other of the wire in the cross direction. They can also be present in the form of at least one continuous strip along the length of the wire.

These two possibilities (discontinuity - continuity) can be combined.

One can use either a single type of iridescent marks, or several types of iridescent marks which are differentiated by their iridescences, that is to say by the colors which they produce at given angles. The iridescent marks should preferably be chosen so as to have a good contrast with the background color of the wire.

As support for the safety thread, colorless polyester [or possibly mass-colored (white being considered as a color)] polyester can be used, the polyester having mechanical and chemical properties well suited to the application of safety threads.

The base wire is covered on one or both sides with an opaque layer. Preferably this layer has a color close to that of the part of the document where the wire will be incorporated.

This layer can be provided by a coating or by printing (by rotogravure for example) of a plastic thread (like polyester) and in quantities so as to have a thread whose final opacity is greater than or equal to that of the sheet. where it will be incorporated.

Iridescent marks are placed on one or both sides of the film. However, it is more advantageous to arrange the iridescent marks on both sides so that these marks are present in the windows. In fact, when a wire is introduced into a document by an industrial process, the wire tends to twist and thus it is not always the same face of the wire which appears for a given face of the document.

It may also be advantageous to use a wire in the form of a complex consisting of at least two laminated wires and each with iridescent marks.

The double-sided presence is also interesting if you want to produce documents with windows on both sides.

Preferably, the iridescent marks are deposited by gravure printing or screen printing.

The iridescent marks can for example be made with an iridescent mineral pigment such as a mica coated with titanium dioxide or with a plastic pigment composed of a special stack of films producing an iridescent effect when the pigment is observed from a certain angle; the pigments are mixed with a transparent binder which has good adhesion with the film material.

The film is then cut into strips which preferably have a width of between 0.8 and 2 mm. However, wider wires may be suitable for the invention.

The invention also aims to provide a security document containing a security thread which can be detected both visually and on a sorting machine.

On a sorting machine, documents are detected, for example, by measuring the electrical conductivity of the security wire or by capacitive measurement linked to the presence of the wire (see patent FR 1570807). For such detections, the wire must include electrically conductive parts.

In the case of the conductivity measurement, the electroconductive part must be continuous all along the wire. The wire is made conductive by adding an electrically conductive layer on at least one of the faces of the base wire. As a conductive layer, it is possible to use a metallic layer produced by vacuum deposition of an electroconductive metal (aluminum, chromium, nickel for example) or produced by coating or printing an electroconductive ink (metallic ink or carbon black ink by example).

The conductive layer or layers are masked by covering the two faces of the wire with at least one layer, preferably having a color close to or identical to that of the document in which the security wire will be incorporated. Iridescent marks are then applied to one or both sides of the wire in accordance with the invention.

One can also detect a wire on a sorting machine thanks to the magnetism of the wire. In this case, the magnetic wire must be returned by adding a magnetic element to it. One can for example make the wire magnetic by depositing a layer of metal oxides (iron oxide for example).

As for the conducting wire and in accordance with the invention, the magnetic layer is then masked and iridescent marks are worn.

It is also possible to combine an electrically conductive layer on one side of the wire and a magnetic layer on the other side.

The invention is not limited to detection by measurement of electrical conductivity or of capacity or magnetism; it is only necessary that the colored layer and the iridescent marks do not disturb the detection.

To make a security wire comprising a detectable element on a sorting machine, in particular an electroconductive or magnetic one, it is possible to use a complex wire, as described above, consisting of at least two wires and such that the detectable element is located inside the complex. This notably prevents the layers or bands of this element from cracking (the discontinuity of an electrically conductive layer is troublesome if one wishes to measure its conductivity).

This complex can be obtained by laminating, for example, two films "iridescent marks / colored layer / polyester yarn / layer of a machine detectable element // adhesive // polyester film / colored layer / iridescent marks.

The colored layers and the iridescent marks can be applied after the two films have been bonded; each film may include a detectable layer; the adhesive may include a detectable material.

The complex can also be obtained by incorporating a detectable sheet between two films; the colored layers and the iridescent marks are preferably provided after the incorporation of the detectable sheet. The detectable sheet can be incorporated between the two films, in particular by gluing.

To detect the wire by measuring the electrical conductivity, it is possible to use as detectable sheet, an aluminum sheet for example.

The printable sheet according to the invention is based on cellulose fibers; it can optionally include synthetic fibers. It can include other elements of authentication or tampering well known to those skilled in the art (watermarks, fluorescent fibers, chemical agents sensitive to solvents, acids, bases, redox agents, etc.).

The following nonlimiting examples of the invention, with reference to the appended drawings, will make it possible to better understand how the invention can be implemented.

Figure 1a shows a yarn according to the invention having strips transverse iridescent.

1b shows the wire of Figure 1 in cross section.

Figures 2 to 5 show other embodiments of the wire according to the invention.

The yarn of FIGS. 1 a and 1 b consists of a strip of polyester P coated on one side with an opaque colored layer C and on one side with the iridescent marks I. These iridescent marks are present on the wire in a discontinuous manner and at regular intervals spaced by a pitch e equal to approximately that of the windows of the sheet into which the wire is intended to be introduced. These marks go from one edge to the other of the wire in the cross direction. In Figure 1 these marks are cross bars, in Figure 2 these marks are characters.

According to another embodiment shown in Figures 3 and 4, the marks are present in the form of one or two continuous bands along the length of the wire.

In Figure 5, there is shown a wire according to the invention which has discontinuous and continuous combined marks.

EXAMPLE 1 :

On one side of a transparent polyester film 12 μm thick, an opaque white layer produced from a white mineral pigment, coated titanium dioxide, is deposited using a MEYER bar n ° 1. vinyl resin and dispersed in methyl ethyl ketone.
The composition is deposited in an amount such that the opacity of the wire is 88 photovolts.
On the other side of the white coated polyester film, discontinuous iridescent marks are deposited, at regular intervals, by gravure printing (as in FIG. 1).

• substance iridescente :    60 parties
  mica enrobé de dioxyde de titane présentant une iridescence jaune-verte.
• liant polymère vinylique :   40 parties

The iridescent composition includes, in dry:

• iridescent substance: 60 parts
  mica coated with titanium dioxide with a yellow-green iridescence.
• vinyl polymer binder: 40 parts

The film is cut into strips 1 mm wide.
The wire is introduced into a sheet of white paper (opacity 85 photovolts) according to the method described in patent EP 59056 and such that the iridescent marks appear in the windows on the surface of the paper.

In transmitted light, a continuous dark wire is observed. In reflected light, only the iridescent marks are observed at an angle of about 45 degrees in the windows of the document.

Iridescent marks have good resistance to traffic

EXAMPLE 2 :

One face of a polyester film 12 μm thick is metallized by deposition (under vacuum) of a continuous layer of aluminum.

On each side of the wire, the opaque white layer described in example 1 is deposited. On this white layer, iridescent marks are printed in yellow-green (cf. example 1) in continuous bands.

Then iridescent marks are printed with pigments having a pink iridescence, discontinuously at regular intervals and such that they form an angle of approximately 45 ° with the marks in yellow-green.

The film is cut into wires 1 mm wide, and such that the iridescent marks in continuous strips are centered on the middle of the wire and of a width less than that of the wire.

The wire is incorporated into white paper according to Example 1.

The same observations are made as in Example 1.

EXAMPLE 3 :

A 6 µm thick aluminum foil is glued between two transparent polyester films 6 µm thick each.

Each face of the complex obtained is covered with the white layer made according to Example 1.
One or both sides are printed by gravure printing with the iridescent pigments used in Example 1. The complex obtained is cut into wires 1.2 mm wide. The complex obtained is incorporated into white paper as in Example 1.

In transmitted light, a continuous dark wire is observed. In reflected light, we observe the iridescence in the windows on the surface of the paper

The wire can also be detected on a sorting machine by measuring the conductivity or the electrical capacity of the document obtained according to the invention.

Claims (11)

1. A security document containing a security thread visible in transmitted light and appearing at certain places called windows on the surface of the document, characterised in that the thread is opaque and on at least one surface has iridescent marks which appear at least partially in at least one of the windows on at least one surface of the document.
2. A security document according to claim 1, characterised in that the thread has the same background colour as the part of the document where the thread is to be introduced.
3. A security document according to claim 1 or 2, characterised in that the iridescent marks on the thread are discontinuous, preferably at regular intervals separated by a spacing equal approximately to the spacing between the windows.
4. A security document according to claim 1 or 2, characterised in that the marks are in the form of a continuous band along the thread.
5. A security document according to any of claims 1 to 4, characterised in that the thread has iridescent marks with varying iridescence.
6. A security document according to any of claims 1 to 5, characterised in that the iridescent marks are on both sides of the thread.
7. A security document according to any of claims 1 to 6, characterised in that the security thread is a complex of at least two threads.
8. A security document according to any of claims 1 to 7, characterised in that the security thread is detectable both visually and on a sorting machine.
9. A security document according to claims 7 and 8, characterised in that the security thread is in the form of a complex comprising at least two threads between which at least one component detectable on a sorting machine is disposed.
10. A security document according to claim 8 or 9, characterised in that the thread comprises at least one electrically conductive detectable component.
11. A security document according to any of claims 8 to 10, characterised in that the thread comprises at least one magnetic detectable component.

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