EP2235260A1

EP2235260A1 - Security paper

Info

Publication number: EP2235260A1
Application number: EP08866860A
Authority: EP
Inventors: Michel Camus
Original assignee: ArjoWiggins Security SAS
Current assignee: ArjoWiggins Security SAS
Priority date: 2007-12-28
Filing date: 2008-12-19
Publication date: 2010-10-06
Also published as: US20110142279A1; FR2925924A1; US8449719B2; FR2925924B1; WO2009083689A1; CA2710870A1; BRPI0821478A2

Abstract

This invention relates to a security paper (1) comprising a fibrous substrate (2) comprising a watermark (3) having repeating motifs (6), and a security structure (10) that does not completely cover the watermark and has at least one semi-reflective area (18) which is superposed at least partly on the watermark; which paper on the one hand allows observation, through the semi-reflective area (18), at least partially, of one of the motifs (6), and on the other hand allows observation at least partially of another of said motifs (6) in a region (3a) of the watermark (3) that is not covered by the security structure.

Description

Security paper

The present invention relates to security papers comprising a fibrous substrate having a watermark and a security structure.

To authenticate a paper document, a watermark is commonly used. This watermark can be a so-called dark watermark. Such a watermark is obtained during the manufacture of the fibrous sheet by means of round shapes or filigranous rollers in the case of a flat-bed machine, comprising the engraved imprint of the watermark to be reproduced. The result is a sheet with a watermark that appears dark when you look at the sheet in transmitted light. The dark areas are due to an accumulation of fibers, during the formation of the sheet, in the hollow parts of the filigraneur means; thus, the thickness of the sheet and the density of the fibers are greater in these areas than in the rest of the sheet.

So-called watermarks can be made on a flat-bed machine by pressing a water-repellent roller on the wet jet. The watermark is then obtained through the raised portions of the filigree roller, by a simple displacement of the fibers, decreasing the density of material locally, and not by accumulation of fibers.

Imitations of true clear watermarks can be obtained by chemical processes of locally transparent support. The addition of binder or resins filling the microporosities of the paper allows the light to cross more easily the support, giving the appearance of a clear watermark in transvison.

Other techniques also allow the transparency of a paper by local compression of the fibrous mat. These technologies are only artifices and are distinguishable from a true clear watermark resulting from a movement of fibers.

The application EP 1 122 360 discloses a paper comprising at least one multitone watermark, comprising, when observed in transmitted light, a set of light zones arranged in the manner of a halftone image. The watermark may have more than two optical densities. The depth of the light areas of the watermark is for example between 50 and 90% of the total thickness of the paper.

European Patent EP 1 252 389 B1 discloses a paper having a network of cells.

EP 0 773 320 A1 discloses a watermark cooperating with a security band. GB 2 250 473 discloses a security thread which may extend into a watermark.

The application FR 2 871 174 describes a support on which is deposited a semi-reflective coating. The application WO 2005/106118 describes a substrate comprising a watermark covered by a security structure comprising metallized zones superimposed on the watermark.

The application US 2006/0127649 describes a substrate comprising a watermark completely covered on both sides by a security structure. There is a need to benefit with security documents, used for example for the manufacture of banknotes or other valuable documents, security features visible to the general public, easily recognizable and difficult to counterfeit.

The invention aims to meet this need. According to one of its aspects, the subject of the invention is a security paper comprising: a fibrous substrate comprising a watermark having patterns repeating itself, a security structure not completely covering the watermark and comprising at least one semi-circular zone; reflective material overlapping at least partially the watermark, the paper allowing on the one hand to observe through the semi-reflective zone at least partially one of the patterns repeating and secondly to observe at least partially another of said patterns in a region of the watermark not covered by the security structure. Preferably, the size of the semi-reflective zone is sufficient to allow a complete observation of at least one of said patterns and the size of the region of the watermark not covered by the security structure is also sufficient to permit complete observation. in this region at least one of said other patterns.

By "semi-reflective" it is necessary to understand at least a partial reflection which is preferably of the specular type, such as a mirror without a tain for example.

Thanks to the invention, the public has a relatively inexpensive and easily recognizable means for authenticating the paper. The observer can compare the watermark as it appears through the semi-reflective zone (s) and as it appears in the region outside the security structure.

The watermark advantageously has a repeating pattern that is well identifiable by the public, for example a simple geometric shape pattern such as for example a circle, a polygon, a star, a logo, a text, for example at least one letter or a number.

The one or more semi-reflective zones may have an outline substantially of the same shape as the pattern of the repeating watermark. This can bring an additional aesthetic effect.

Repeating patterns can be repeated with a constant spacing in at least one direction and repeated in this direction for example more than three times, better five times.

The watermark may be a watermark formed during the manufacture of the substrate in a paper machine, preferably a round one. The watermark can be a clear watermark, as opposed to a dark watermark. A clear watermark is a watermark appearing brighter than the rest of the paper during a transvision observation, for example in daylight, coming from a lower local material density, which causes a local decrease in the opacity of the paper. paper. Preferably, the watermark is a watermark with multiton effect, composed of light areas, ie areas of thickness less than the thickness of the remainder of the sheet, arranged so as to form a raster pattern. Such screened watermarks have been described in patent application EP 1122360. Such a watermark has the advantage of being particularly difficult to reproduce because of the fineness of its structure, while being very easily recognizable by the public.

The security structure may extend from a first edge of the paper to a second edge opposite the first edge, the security structure being for example a band of constant width or not. The security structure can still be a patch. In an exemplary implementation of the invention, the security structure has at least one opaque zone superimposed at least partially on the watermark. This opaque zone can be reflective, which can make it possible to obtain a substantially united bottom when the safety structure is observed in reflection, the semi-reflective zone or zones becoming apparent only in transvision.

The opaque zone, especially reflecting zone, may be juxtaposed with the semi-reflective zone, the opaque zone surrounding for example completely the semi-reflective zone.

The security structure may include a plurality of semi-reflective zones. The entire surface of one face of the structure may be reflective or semi-reflective.

The security structure may include transparent windows, made for example by cutting or demetallization.

The security structure may comprise a holographic layer, the latter extending for example over an entire face of the security structure, or comprise other security elements using the reflectivity of the structure, for example liquid crystals. The one or more semi-reflective zones and the reflective zone or zones may be formed by a metal deposit of variable thickness, the metal being, for example, aluminum. The one or more semi-reflective zones may define patterns that repeat at regular intervals or not, these patterns defining windows and / or text.

The one or more semi-reflective zones may have, with the rest of the structure, when observed by transvision, an optical density difference greater than 1, for example between 5 and 80 units, measured with a spectrophotometer (ISO 2471 background substrate). preferably 35-40.

The opacity gap between the semi-reflective and opaque regions, when the structure is observed in transvision (examination of the transmitted light), may depend on the manner in which these regions are made, this opacity difference being adjusted to allow a contrast easily visible by transvision in the light of day.

Other technologies for obtaining reflective material while being transparent or of low opacity, are known to those skilled in the art, such as the use of materials having a large difference in refractive index with their associated support (polymer film type polyester for example). Such materials are well known, for example in the realization of transparent holographic security. These are, for example, metal salts of general formula TiO (x) or such as Zinc sulphide (ZnS). It is also possible to use iridescent "Iriodin" pigments (produced by Merck), given that the opacity depends on the quantity of pigments deposited.

The security structure may comprise a support made of a transparent thermoplastic material.

The security structure may be bonded to the fibrous substrate, for example being disposed on the face of the substrate opposite to the watermark.

The invention further relates, in another aspect, to a document comprising a security paper as defined above. The invention further relates, in another of its aspects, to a method for authenticating a security paper as defined above, comprising the step of observing in transvision through the semi-reflecting zone the watermark and to conclude as to the authenticity of the paper at least from the image thus observed, in particular by comparing the watermark patterns observed respectively without superposition to the security structure and in superposition with at least one semireflecting region.

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: FIG. FIG. 2 shows the paper of FIG. 1 when viewed in transvision, FIG. 3 is a section along III - III of FIG. 2, and FIG. FIG. 4 is a partial front view of a variant of paper made according to the invention.

In the figures, the relative proportions of the different constituent elements have not been respected and do not correspond to the reality, for the sake of clarity.

The security paper 1 shown in FIGS. 1 to 3 comprises a fibrous substrate 2 in which a watermark 3 is produced by a known technique for producing a watermark. The fibrous substrate 2 comprises, for example, papermaking fibers, in particular cellulose fibers, and the watermark 3 is for example a clear watermark, being made hollow in the thickness of the fibrous substrate, on a face 12 thereof.

The watermark 3 may comprise a plurality of patterns 6 which are repeated, these patterns 6 having for example a simple geometrical shape, easily recognizable by the observer, for example a geometric shape such as a circle, a polygon, a star, a logo, a letter or a number. The paper 1 comprises a security structure 10 which is for example fixed on the face 11 of the substrate 2 opposite that in which the watermark 3 is made. The security structure 10 comprises a support 15, for example a translucent or transparent film, for example made in a thermoplastic film, such as a polyester film, PVC, PP, an aromatic polyamide or aramid, or other polymers, and a deposit 16 of varying thickness of a metal, an alloy or metal oxide for example, aluminum, copper, zinc, gold or platinum, the lesser areas defining semi-reflecting areas 18 while the areas of greater thickness defining opaque reflecting areas.

The thickness of the metal in the semi-reflective zones 18 is sufficiently small to give them a semi-reflective character, allowing to see through in transvision. As an indication, the thickness of a semi-reflective thinned layer 18 is for example between 5 and 50 nm and the thickness of the deposition in the regions 20 is for example between 100 and 300 nm.

In the illustrated example, the security structure comprises a plurality of semi-reflecting zones 18, which extend for example at regular intervals along the structure, for example in the form of windows.

The semi-reflective zones 18 may have various shapes, for example being of polygonal outline, for example rectangular as illustrated, or circular outline, or shapes corresponding to text or a logo or any other reason.

The invention is not limited to a particular way of obtaining the semi-reflecting 18 and opaque 20 regions, and it is possible for example to deposit on the support a first reflecting material whose opacity is sufficiently weak to define the semi-reflecting region 18 and, at locations 20 of greater opacity, deposit a second reflective material on the first material. The first material is for example a metal such as aluminum and the second material is for example an oxide such as TiO _x or ZnS, deposited under vacuum.

The semi-reflecting zones 18 may for example be made using an interference pigment, for example a titanium-based mica-based wafer or a titanium-oxide coated glass wafer, and Reflective zones 20 with higher opacity can be achieved using an ink, for example based on aluminum powder.

The security structure 10 may comprise a holographic layer 22 made by embossing a varnish deposited on the security structure, so as to create a microrelief for generating a hologram.

The holographic layer may be covered with a layer of a protective varnish, if appropriate.

The authentication of the paper 1 can be performed by comparing the appearance of the paper observed in reflection to the latter observed in transvision.

In reflection, the reflecting zone (s) 20 and the semi-reflecting zone (s) 18 form a substantially plain reflective background, which makes it possible to observe the color produced by the hologram. In reflection, the watermark 3 does not appear or is not very visible. In transvision, the one or more semi-reflecting zones 18 make it possible to observe through them the watermark 3 and the observer can compare the patterns 6 of the watermark that appear in the semi-reflecting zone (s) 18 and those that appear through the substrate 2 next to the security structure 10, in the region 3a of the watermark 3 not covered by the security structure. In the variant illustrated in FIG. 4, the semi-reflecting zones 18 are sufficiently large to allow the observation of at least one pattern 6 of the watermark in transvision, in order to compare it with another pattern 6 in a region of the watermark 3 not covered by the structure 10.

The security structure 10 may have a different shape, not being limited to a band and being able for example to be in the form of a patch, such a patch being for example intended to be glued to one face of the object to secure, in a transparent or translucent region thereof. In the illustrated examples, the security structure 10 is disposed on the face 11 of the substrate 2 opposite that in which the watermark 3 is made, but it could be different, and one can for example have the watermark and the structure on the same side.

Although a clear watermark is preferable, especially in order not to generate extra thickness in the paper, a dark watermark can also be used.

The expression "having one" shall be understood as being synonymous with "having at least one", unless the opposite is specified.

Claims

A security paper (1) comprising: a fibrous substrate (2) having a watermark (3) having repeating patterns (6); - a security structure (10) not completely covering the watermark and having at least one semi-reflecting zone (18) superimposed at least partially on the watermark, the paper making it possible on the one hand to observe, through the semi-reflecting zone (18), at least partially one of the patterns (6), and on the other hand to observe at least partially another of said patterns (6) in a region (3a) of the watermark (3) not covered by the security structure.

2. Paper according to claim 1, the watermark being a clear watermark.

3. Paper according to one of the preceding claims, the security structure (10) extending from a first edge of the paper to a second edge, opposite the first.

4. Paper according to claim 3, the security structure (10) being in band.

5. Paper according to any one of the preceding claims, the security structure having at least one opaque zone (20) superimposed at least partially on the watermark.

6. Paper according to claim 5, the opaque zone (20) being reflective.

7. Paper according to claim 5 or 6, the opaque zone (20) being juxtaposed with the semi-reflecting zone (18).

8. Paper according to the preceding claim, the opaque zone (20) completely surrounding the semi-reflective zone (18).

The paper of any preceding claim, the security structure having a plurality of spaced semi-reflective zones (18).

10. Paper according to any one of the preceding claims, the size of the semi-reflective zone (18) being sufficient to allow complete observation of at least one of said patterns (6).

11. Paper according to any one of claims 1 to 10, the watermark and the security structure being arranged to allow to completely observe at least one said patterns (6) in a region (3a) of the watermark (3) not covered by the security structure (10).

The paper as claimed in any one of the preceding claims, the security structure comprising a holographic layer (22).

13. Paper according to claims 1 and 6, the semi-reflective zone (18) and the reflective opaque zone (20) being formed by a metal deposit of variable thickness.

14. Paper according to any one of the preceding claims, the semi-reflecting zone (18) having, with the rest of the structure, when observed in transvision, an optical density difference greater than 1.

15. Paper according to any one of the preceding claims, the security structure comprising a support (15) of transparent thermoplastic material.

16. Paper according to any one of the preceding claims, the security structure (10) being bonded to the fibrous substrate (2).

17. Paper according to any one of the preceding claims, the security structure (10) being disposed on a face of the substrate (12) opposite the watermark (3).

18. Document comprising a security paper as defined in any one of the preceding claims.

19. A method of authenticating a security paper, as defined in any one of claims 1 to 17, including the step of observing in transvision through the semi-reflective zone the watermark (3) and to conclude as to the authenticity of the paper at least from the image thus observed.