EP1786631B1 - Security printing process and security document - Google Patents

Abstract

The method involves placing a protecting layer on a surface of a security document e.g. bank note (1). A rough region (3) for receiving a letterpress unit e.g. alphanumeric serial number (4), signature or bar code, is formed on the security document. The letterpress unit is printed on the security document. The region is constituted of frame of points or lines, and size of the region is higher than that of the unit. An independent claim is also included for a security document e.g. bank note, or paper representing a value.

Description

The present invention relates to a method for printing security documents, such as banknotes and securities, including in particular a varnishing step during which there is a protective layer on the surface of said security documents and a step of typographic printing during which at least one typographic element is printed on said security documents. The invention also relates to such a security document.

In order to protect banknotes and papers valuable premature wear due to handling they undergo and extend their life, a protective layer is applied to the sheets or the coil on which are printed during one of the final stages of the manufacturing process.

In the document FR-A-523 278 such a protective layer had already been provided for printed matter and the like. In documents EP-A-0256170 and EP-A-0860296 the production of bank notes and value papers with a protective layer is described. In the US Patent 6227572 relief elements are created by deforming the paper to form, for example, an indication in Braille of the value of the ticket for the visually impaired. At least the zone comprising these elements in relief is reinforced by a layer of a varnish.

When making a banknote or paper value, after the two-sided printing of the paper and the control of the print quality, the banknotes that meet the quality criteria are numbered, a protective varnish is applied as described for example, in the aforementioned documents and then the sheets undergo the final stages of finishing, such as cutting into individual bills, forming packages, counting, etc. When applying the protective varnish on both sides of each leaf some leaves may be partially or completely smeared. In this case the already numbered banknotes are unusable and either the missing numbers need to be reused on other sheets, or the printing of a special series and these new sheets have to be inserted in the stack in the right place to obtain bundles with a numbering that follows.

To avoid this tedious and costly work, it was proposed to print the numbers or other typographic element on the banknotes and papers value after the application of the protective layer and a quality control to remove the leaves or tickets stained We limit thus the printing of a special numbering or retrieval of unused numbers to any improperly printed numbers.

It turned out that the adhesion and strength of the letterpress inks used for printing the numbering on the paper with the layer of protection, especially when it comes to a layer of UV curing varnish, is very low. In addition, when the printing of the face of the bill on which the number is printed is made in intaglio, the paper is subjected to a very strong pressure and it became smooth which does not facilitate the adhesion of the ink used for numbering.

The present invention provides a method of printing at least one typographic element on security documents such as banknotes and value papers varnished and to overcome these disadvantages.

The method according to the invention is characterized by the fact that said typographic printing step is carried out after said varnishing step and by forming on said security documents, before said typographic printing step, at least a rough field for receiving said at least one typographic element.

The roughness of the field created and intended to receive the typographic element, such as an alphanumeric serial number, a signature, a date of issue or other, allows a good adhesion of the typographic ink. The typographic element may also be any other single sign-on element for a security document such as a barcode or other drawing readable by a special machine and having elements that differ from one security document to another.

According to one variant, the rough field consists of a grid of dots or lines.

According to one variant, the rough field is formed before or after said varnishing step by locally increasing the roughness of the surface of said security documents.

According to another preferred variant, said rough field is formed by an intaglio printing process the intaglio printing plate whose area intended to form a rough field is or not inked.

According to another variant, the rough field may be made by stamping before or after the varnishing step or by any other means making it possible to increase the roughness of the surface of the substrate or of the protective layer, for example a treatment localized chemical or by treatment by means of a beam such as a laser beam striking the surface of the document.

According to one variant, the size of the rough field is greater than the size of the typographic element to be printed there.

According to one variant, the protective layer is produced by means of a UV-drying varnish.

The invention also relates to a security document according to one of claims 11 to 14.

The invention will be described in more detail with the aid of the single figure schematically showing a banknote seen in plan.

Banknote 1 is printed recto-verso according to conventional methods used in the field of the printing of banknotes and paper value, that is to say, offset printing, intaglio, Orloff, screen printing etc. . When printing the pattern 2 on the front face of the ticket 1, a rough field 3 is created, advantageously in an intaglio printing process. The intaglio printing plate comprises an area identical in size to the field 3, provided with several notches of different shape and depth which, during the passage of the paper between the intaglio plate and the plate of the printing cylinder, will form on the paper a rough field including in relief a frame of lines and points corresponding to the notches located on the plate intaglio. These reliefs can be almost invisible to the naked eye, if said area of the intaglio plate is not inked, but they can be detected by touch. We have represented these reliefs by dots and fine lines in the figure. After having passed through the various quality controls, the non-rejected leaves are covered with a protective layer such as, for example, a UV-curing varnish (it could alternatively be another type of varnish, such as a varnish infrared drying). After drying the varnish and a final check to remove the stained leaves during the application of the protective layer, the leaves pass into a conventional numbering machine which applies an individual serial number 4 (as well as other unrepresented typographic elements such as a signature or a date of issue) on each unspotted ticket 1. The rough field 3 allows a good adhesion of the typographic ink despite the presence of the protective layer.

Subsequently the sheets are sent to the usual finishing facility, control of the printing of the numbering, cutting, formation of bundles etc.

Field 3 extends around the number or typographic element so as to cover a higher surface (a few tenths of a millimeter is sufficient) and take into account any inaccuracies when printing the numbering.

As previously mentioned, several typographic elements can be printed on a security document such as a bank note, for example, the serial number, a signature, the date of issue, or any other element that it is desirable to print by typography.

The use of the intaglio printing plate for producing the rough field 3 is a preferred embodiment. Nevertheless, one can alternatively form the rough fields by stamping, by a localized chemical treatment or by means of a beam striking the surface of the security document, for example a laser beam. This operation can also be performed independently before or after the provision of the protective layer. What is important is to create, before the printing of the typographic element, a rough field allowing a good adhesion of the typographic ink on the protective layer. The production of the field 3 during intaglio printing is particularly advantageous in that it does not require an additional step. It suffices simply as already mentioned to provide an appropriate field on the intaglio printing plate.

The invention also relates to a security document, such as that described using the figure 1 comprising a substrate whose faces bear prints, a protective layer affixed to said substrate, and a rough field on which is printed a typographic element affixed to said protective layer.

The rough field may be formed, before varnishing, roughness formed on the surface of said substrate so that these asperities are reflected on the surface of said protective layer after varnishing. Alternatively, the rough field may be formed, after varnishing, asperities formed directly on the surface of said protective layer. As already mentioned, the asperities are preferably constituted by a grid of dots and / or lines.

Claims (14)

1. Method for printing security documents, such as banknotes and security papers, comprising especially a lacquering step during which a protective layer is deposited on the surface of said security documents and a letterpress printing step during which at least one typographical element is printed on said security documents, characterized in that said letterpress printing step is carried out after said lacquering step and in that, before said letterpress printing step, at least one roughened field intended to receive said at least one typographical element is formed on said security documents, which roughened field has asperities for increasing the adhesion of said at least one typographical element on said protective layer.
2. Method according to claim 1, characterized in that the typographical element is an alphanumeric serial number, a signature or a date of issue.
3. Method according to claim 1 or 2, characterized in that the roughened field has asperities consisting of a grid of dots and/or lines.
4. Method according to one of claims 1 to 3, characterized in that said roughened field is formed, before or after said lacquering step, by locally increasing the roughness of the surface of said security documents.
5. Method according to claim 4, characterized in that said roughened field is formed, before or after deposition of the protective layer, by stamping.
6. Method according to claim 4, characterized in that the roughened field is formed, before or after deposition of the protective layer, by a chemical treatment.
7. Method according to claim 4, characterized in that said roughened field is formed, before or after deposition of the protective layer, by a treatment using a beam that strikes the surface of the document.
8. Method according to claim 4, characterized in that said roughened field is formed before said lacquering step by an intaglio printing process using an intaglio printing plate whose region intended to form said roughened field may or may not be inked.
9. Method according to one of claims 1 to 8, characterized in that the size of the roughened field is greater than the size of the typographical element that has to be printed thereon.
10. Method according to one of claims 1 to 9, characterized in that said protective layer is produced by means of a UV-curable lacquer.
11. Security document, especially a banknote or a security paper, comprising a substrate, the faces of which bear prints, a protective layer affixed to said substrate, and a roughened field on which a typographical element affixed to said protective layer is printed, which roughened field has asperities for increasing the adhesion of said at least one typographical element on said protective layer.
12. Security document according to claim 11, characterized in that the roughened field is formed from asperities made on the surface of said substrate and being manifested on the surface of said protective layer.
13. Security document according to claim 11, characterized in that the roughened field is formed from asperities made directly on the surface of said protective layer.
14. Security document according to one of claims 11 to 13, characterized in that the roughened field has asperities consisting of a grid of dots and/or lines.

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