CA2661570C

CA2661570C - Security paper sheet with intaglio printing motif

Info

Publication number: CA2661570C
Application number: CA2661570A
Authority: CA
Inventors: Peter Franz
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2006-08-22
Filing date: 2007-08-09
Publication date: 2015-06-02
Anticipated expiration: 2027-08-09
Also published as: RU2450938C2; EP2057020A1; MY180635A; WO2008022714A1; RU2009109383A; EP2057020B1; CA2661570A1; DE102006039306A1

Abstract

The invention relates to a method of producing a security paper sheet for security documents or documents of value (10) wherein the security paper sheet is provided in an intaglio printing step with at least one intaglio printing motif (12, 14) with a raised relief structure, and wherein according to the invention during the intaglio printing step a plurality of equalizing elements (16) distributed over the area of the security paper sheet are additionally produced with a raised relief structure for equalizing the profile of the security paper sheet.

Description

Security paper sheet with intaglio printing motif The invention relates to a security paper sheet for the production of security documents or documents of value and the like having at least one intaglio printing motif with a raised relief structure. The invention further relates to a corresponding production method and to an intaglio printing plate for em-bossing this type of security paper sheet.
Security documents and documents of value, the commercial or utility value of which exceeds the material value by far, are generally made recognisable as genuine by means of appropriate measures and distinguishable from imi-tations and forgeries. For this purpose they are mostly provided with special security elements which ideally can not be imitated, or only with a great deal of complexity, and can not be forged.
Of particular significance here are those security elements which can be iden-tified by users without any aids and can be recognised as genuine, but which at the same time can only be produced with a high degree of technical com-plexity or financial expenditure. Examples of such security elements are wa-ter marks which can only be inserted into a document of value during the paper production, or printed images produced using the intaglio printing method which are characterised by a characteristic tactility which can also be easily recognised by the layman and which can not be reproduced by any other printing methods and in particular by photocopying machines or scanners.
The line or intaglio printing technique, in particular the steel intaglio print-ing technique, is of great significance to the printing of security papers and documents of value. Intaglio printing is characterised in that in order to produce a desired printed image linear indentations are engraved into a

- 2 -printing plate. These indentations are produced by means of an appropriate engraving tool or by means of etching.
In comparison to other commonly used printing techniques, the intaglio printing technique allows on the one hand a very thick application of ink.
Moreover, the paper can also be pressed into the engraving of the printing plate due to the high levels of printing pressure, even in the ink-free regions, and in this way be provided with an embossed relief structure. The thick layer of ink produced using the intaglio printing method together with the partial deformation of the surface of the paper can also easily be felt manu-ally by the layman and so can also be detected easily as a sign of genuineness by means of its tactility. The tactility can not be imitated using a photocop-ier, and so the intaglio printing technique offers high value protection against forgeries.
When producing security paper sheets the printed sheets are stacked after an intaglio printing step for further processing. Due to the different profile heights of the surface of the sheet and to the embossed intaglio printing ele-ments a substantially undulating stack is often produced here, especially if the sheets are only printed with intaglio print in small partial regions. This makes it easy for the individual sheets to slip and so promotes poor set-off characteristics.
Upon this basis, the underlying object of the invention is to specify a security paper sheet of the type specified at the start which avoids the disadvantages of the prior art, and which in particular has improved stacking characteris-tics during production. In addition to the security paper sheet, the invention should also provide a corresponding production method.

- 3 -This object is achieved by the production method having the features of the main claim. An associated security paper sheet and a corresponding intaglio printing plate are specified in the independent claims. Further develop-ments of the invention form the subject matter of the dependent claims.
According to the invention, with a generic method provision is made such that during the intaglio printing step a plurality of equalizing elements with a raised relief structure are additionally produced which are distributed over the surface of the security paper sheet in order to equalize the profile of the security paper sheet. As described in greater detail below, when stacking the security paper sheets the equalizing elements act as profile equalizing spac-ers, and in this way guarantee improved stacking characteristics and lesser set-off characteristics. Moreover, by means of greater air exchange, better drying of the printing inks of the intaglio printing motifs is also achieved.
Advantageously, the equalizing elements are not only distributed in the re-gion of the individual ups, but over the whole surface of the security paper sheet.
The equalizing elements are advantageously only produced outside of the intaglio printing motifs so as not to effect the design and profile height of the latter.
Preferably, each security paper sheet includes a number of individual ups, 23 the equalizing elements being arranged substantially uniformly within the individual ups in order to achieve a largely uniform profile height overall.
Here the equalizing elements can respectively be arranged in the same way or also differently in different individual ups. The latter makes it possible to

- 4 -use the arrangement of the equalizing elements as machine-readable coding for identifying the individual ups.
Alternatively to or in addition to the coding by means of the arrangement of the equalizing elements, the coding can be achieved by means of different outline shapes and/or edges of the equalizing elements in the individual ups. The edges can preferably be distinguished here by their slope and/or spatial form. For example, the edges can be provided with steps.
The equalizing elements are advantageously produced with soft edges with a slight slope in order to minimise the risk of paper injuries when printing.
The equalizing elements are also preferably formed with rounded outline shapes, such as circles, ellipses or ovals for example.
For effective equalization of the profile one possibility is to produce the equalizing elements with a large engraving depth. Advantageously the en-graving depth of the likewise introduced intaglio printing motifs is taken into account here since it is generally sufficient for the profile equalization if the engraving depth of the equalizing elements is in the region of the maxi-mum engraving depth of the intaglio printing motifs. Within the framework of the invention one is dealing in particular with embodiments with an en-graving depth of between 40 gm and 260 gm, preferably between 60 gm and 120 gm, and particularly preferably between 80 gm and 100 gm.
The equalizing elements can be formed as blind embossings or also be printed ink-receptively.
In a further development of the method, in a further intaglio printing step after the first intaglio printing step the security paper sheet is provided with

- 5 -at least one further intaglio printing motif, the equalizing elements being substantially levelled during the further intaglio printing step. Whereas the advantages of the method can then be used for the first intaglio printing step, the completed security paper has a smooth surface without any tactilely de-tectable equalizing elements.
In particular, provision can be made such that in the first intaglio printing step and the further intaglio printing step the security paper sheet is pro-vided on opposite sides with intaglio printing motifs. Advantageously, the designs of the intaglio printing motifs produced in the first intaglio printing step and of the further intaglio printing motifs produced in the further inta-glio printing step are matched to one another in order to substantially level the equalizing elements of the first intaglio printing step during the further intaglio printing step.
In a further advantageous embodiment of the invention the security paper sheet includes a number of individual ups, at least part of the equalizing elements being arranged with an elongate form in one or more corners of the individual ups. The cut out documents of value can in this way be provided with increased stability in the corner regions particularly susceptible to bending. According to a further advantageous embodiment at least part of the equalizing elements are arranged with an elongate form at one or more edge centres of the individual ups. The cut out documents of value can in this way be provided with increased stability in the central regions particu-larly subjected to folding.
The invention also includes a security paper sheet for the production of secu-rity documents or documents of value and the like, with at least one intaglio printing motif with a raised relief structure. A plurality of equalizing ele-

- 6 -ments with a raised relief structure are distributed here over the surface of the security paper sheet for equalizing the profile of the security paper sheet.
Details of the design and arrangement of the equalizing elements can be taken from the description given above of the generic production method.
The invention also includes a document of value, such as a bank note, an identity card or the like, which is produced from a security paper sheet of the type described.
The invention further relates to an intaglio printing plate for embossing a security paper sheet for security documents or documents of value having at least one engraved motif in the form of a relief structure wherein a plurality of equalizing engraved elements distributed over the surface of the intaglio printing plate are provided with a relief structure for equalizing the profile of the security paper sheet to be printed. Preferably, the equalizing engraved elements are distributed over the whole surface of the intaglio printing plate, i.e. not only in the regions for the individual ups.
During the intaglio printing step the engraved motifs of the printing plate produce the aforementioned intaglio printing motifs in the security paper sheet, and the equalizing engraved elements produce the aforementioned equalizing elements. The details of the design and arrangement of the equal-izing engraved elements can therefore be taken from the above description of the generic production method.
Further exemplary embodiments and advantages of the invention are de-scribed in the following by means of the figures. For better clarity an illus-tration true to scale and in proportion is dispensed with in the figures.

- 7 -The figures show as follows:
Fig. 1 a diagrammatic view of a bank note according to the invention with two intaglio printing motifs and a plurality of blind em-bossed equalizing elements, Fig. 2 a cross-section through the bank note along line II-II of Fig.
1 in the region of one of the embossed equalizing elements, Fig. 3 in (a) a conventional security paper sheet with printed intaglio printing motifs, and in (b) the undulating stack produced when stacking the sheets of (a), Fig. 4 in (a) a security paper sheet according to the invention with printed intaglio printing motifs and blind-embossed equalizing elements, in (b) a number of security paper sheets according to the invention stacked over one another, and in (c) the even stack produced when stacking the sheets of (a), Fig. 5 a bank note with blind-embossed equalizing elements specifi-cally arranged in the corners, (a) and (b) showing two exem-plary embodiments, and Fig. 6 a bank note with blind-embossed equalizing elements specifi-cally arranged at the edge centres, two different embodiments being shown in the partial images.
The invention is now described in greater detail using the example of a bank note. For this purpose Fig. 1 shows a diagrammatic view of a bank note 10

- 8 -which, in addition to conventional design and security elements not shown in the figure, has two intaglio printing motifs 12 and 14, namely a portrait illustration 12 and a value figure 14 which can be detected tactilely by the user.
In addition, the bank note 10 includes a plurality of equalizing elements 16 blind embossed in the intaglio print and having a raised relief structure which serve to equalize the profile of the security paper sheets when produc-ing bank notes 10 in the way described below. The equalizing elements 16 are distributed over the surface of the bank note 10 outside of the design elements 12 and 14 and are barely noticeable to the user due to the blind em-bossing.
Fig. 2 shows a cross-section through the bank note 10 along line II-II of Fig.

in the region of one of the embossed equalizing elements 16. As can be seen by considering Figures 1 and 2 together, the equalizing elements 16 are formed with round shapes, for example in the form of flat pimples. As emerges from the cross-sectional illustration of Fig. 2, the equalizing ele-ments 16 appearing on the front side of the bank note as elevations 16E form indentations 16V when viewed from the rear side of the bank note. In the exemplary embodiment the lateral extension A of the equalizing elements 16 is approximately 300 !AM and can basically be between approximately 60 gm and approximately 2000 gm.
In the exemplary embodiment the embossing depth h of the equalizing ele-ments 16 is approximately 90 gm, but can also basically be between ap-proximately 40 gm and approximately 260 gm.

- 9 -In order to avoid paper injuries during the intaglio printing step, the equaliz-ing elements 16 are formed with soft edges 18, i.e. with edges with a slight slope. For example, the equalizing elements 16 can have an average edge angle of approximately 30 to approximately 50 . The tear strength of the bank note paper is not effected negatively either by the addition of equaliz-ing elements with soft edges.
The particular advantages offered by the equalizing elements 16 when pro-ducing security paper sheets for documents of value, such as for example the bank note 10, are now described in greater detail by means of the diagram-matic illustration of Figures 3 and 4.
Fig. 3(a) first of all shows a conventional security paper sheet 20 with a num-ber of individual ups 22 which are respectively provided with a portrait il-lustration 12 and a tactilely detectable value figure 14 in the intaglio print.
By means of the different profile heights of the surface of the sheet and the two intaglio printing elements 12, 14, when stacking these types of sheet 20 during production, a substantially undulating stack 24 is produced, as shown in Fig. 3(b). Such undulating stacks 24 make it easy for the individual sheets 20 to slip and so have comparatively poor stacking characteristics.
By using equalizing elements 16 according to the invention the stacking characteristics of the embossed sheets can be significantly improved. For this purpose, Fig. 4(a) shows once again a security paper sheet 30 with a number of individual ups 32 which now has a plurality of blind-embossed equalizing elements 16 in addition to the portrait illustrations 12 imple-mented in the intaglio print and the tactilely detectable value figures 14.

- 10 -The engraving depth of the equalizing elements 16 is applied here to the en-graving depth of the intaglio printing motifs 12, 14 and is preferably in the order of magnitude of the largest occurring engraving depth, in the exem-plary embodiment of the engraving depth of the value figure 14. Moreover, the equalizing elements 16 are distributed substantially uniformly over the surface of the security paper sheet 30 and so bring about effective equaliza-tion of the overall profile of the security paper sheet 30.
In this way, when stacking, the security paper sheets 30 according to the in-vention lie on top of one another substantially more evenly and form a sub-stantially more even stack, as illustrated by means of the stack section of Fig.
4(b) and the sectional illustration of a complete stack 34 of Fig. 4(c). A
more even stack can be processed better in the further processing steps. As can be seen directly from Fig. 4(b), the set-off characteristics are also minimised by the equalizing elements 16 acting as spacers.
A further advantage is the improved drying of the intaglio printing inks of the motif elements 12 and 14. When printing conventional security paper sheets 20 those partial regions which do not have any intaglio printing ele-ments 12, 14 are calendered by the high pressure during the intaglio printing step and in this way their profile height is considerably reduced. In the con-ventional stack 24 these often large-scale calendered partial regions are often closely adjacent to one another so that an exchange of air over the surface of the sheet can only take place to a very limited extent.
By means of their spacer function, the equalizing elements 16 according to the invention distributed over the surface of the security paper sheet 30 lead to an improved supply of air to the partial regions 12, 14 printed in the inta-

- 11 -glio print so that the printing ink applied is given more time and more air for drying.
The equalizing elements 16 can be distributed regularly or also irregularly over the surface of the individual ups 32 of the security paper sheet 30. Ad-vantageously however, the maximum distance between adjacent equalizing elements does not exceed a maximum value dependent upon the paper used.
In a further development of the invention it is also possible to vary the ar-rangement of the equalizing elements 16 specifically from up to up. For ex-ample, by means of their arrangement the equalizing elements 16 can pro-duce a machine-readable coding and in this way make it possible to distin-guish between the individual ups 32.
Alternatively or additionally to the equalizing elements distributed substan-tially uniformly over the surface of the individual ups, in certain regions of the individual ups equalizing elements can specifically be provided, as shown in Figures 5 and 6.
With the bank note 40 of Fig. 5 groups of blind-embossed equalizing ele-ments 44 are respectively arranged in the corners 42. In the exemplary em-bodiment of Fig. 5(a) the equalizing elements 44 are formed as elongate ellip-ses the main axes of which are respectively aligned parallel to and substan-tially in the direction of the respective corner 42. A further possibility is shown in Fig. 5(b) in the exemplary embodiment of which the equalizing elements 44 are formed by elongate ellipses with main axes aligned to the respective corner 42.
By means of designs with embossed structures 42 specifically arranged in and aligned to the corners, as shown in Fig. 5(a) or (b), increased rigidity of

- 12 -the bank note 40 in the corners particularly susceptible to bending can also be achieved during production in addition to the equalizing effect already described.
Advantageously, equalizing elements 56 can also be arranged on the edge centres of the longitudinal edges 52 or the lateral edges 54 of a bank note 50, as shown in the two exemplary embodiments of Fig. 6. By means of the em-bodiments shown, or similar ones, the rigidity of the bank note 50 in the re-gion of the edge centres heavily stressed during use by folding can be in-creased.
If the security paper sheets according to the invention are only subjected to an intaglio printing step on one side, the equalizing elements are tactilely detectable after production due to their relief structure. The same applies to the second intaglio printing step with two-sided intaglio printing. Here too the equalizing elements produced during the second intaglio printing step can be felt on the finished security paper.
If the tactile detectability is not desired and if the surface of the security pa-per should be smooth outside of the design elements produced in the inta-glio print, it is possible, for example, with the two-sided intaglio printing to only introduce the equalizing elements during the first intaglio printing step, for example in order to produce the rear side of the bank note. The de-scribed advantages of the invention can then be used for the process steps of 23 the first intaglio printing step.
In a subsequent second intaglio printing step, for example in order to pro-duce the front side of the bank note, no more equalizing elements are em-bossed. In fact, the equalizing elements already existing from the first inta-

- 13 -glio printing step are equalized by the high embossing pressure of the sec-ond intaglio printing step and so no longer appear with the finished security paper. It goes without saying that for this purpose the designs of the front side and the rear side are advantageously appropriately matched to one an-other.

Claims

1. A method of producing a security paper sheet for security documents or documents of value wherein the security paper sheet is provided in an intaglio printing step with at least one intaglio printing motif with a raised relief structure, characterised in that during the intaglio printing step a plu-rality of equalizing elements distributed over the area of the security paper sheet are additionally produced with a raised relief structure for equalizing the profile of the security paper sheet.

2. The method according to claim 1, characterised in that the equalizing elements are produced outside of the intaglio printing motifs.

3. The method according to claim 1 or 2, characterised in that the secu-rity paper sheet includes a number of individual ups, and the equalizing elements are arranged substantially uniformly within the individual ups.

4. The method according to any one of claims 1 to 3, characterised in that the security paper sheet includes a number of individual ups, and the equalizing elements are respectively arranged differently in different indi-vidual ups and/ or the equalizing elements are arranged in different individ-ual ups respectively with a different shape.

5. The method according to any one of claims 1 to 4, characterised in that the equalizing elements are produced with soft edges with a slight slope.

6. The method according to any one of claims 1 to 5, characterised in that the equalizing elements are formed with rounded outline shapes, in par-ticular as a circle, ellipse or oval.

7. The method according to any one of claims 1 to 6, characterised in that the equalizing elements are produced with a large engraving depth, in particular with an engraving depth of between 40 µm and 260 µm, preferably between 60 µm and 120 µm, and particularly preferably between 80 µm and 100 µm.

8. The method according to any one of claims 1 to 7, characterised in that the equalizing elements are formed as blind embossings.

9. The method according to any one of claims 1 to 7, characterised in that the equalizing elements are printed ink-receptively.

10. The method according to any one of claims 1 to 9, characterised in that the security paper sheet is stored in a stack of sheets for further process-ing after the first intaglio printing step.

11. The method according to any one of claims 1 to 10, characterised in that in a further intaglio printing step after the first intaglio printing step the security paper sheet is provided with at least one further intaglio printing motif, and that the equalizing elements are substantially levelled during the further intaglio printing step.

12. The method according to claim 11, characterised in that in the first intaglio printing step and the further intaglio printing step the security paper sheet is provided on opposite sides with intaglio printing motifs.

13. The method according to claim 11 or 12, characterised in that the de-signs of the intaglio printing motifs produced in the first intaglio printing step and of the further intaglio printing motifs produced in the further inta-glio printing step are matched to one another in order to substantially level the equalizing elements of the first intaglio printing step during the further intaglio printing step.

14. The method according to any one of claims 1 to 13, characterised in that the security paper sheet includes a number of individual ups, and at least a part of the equalizing elements are arranged with an elongate form in one or more corners of the individual ups.

15. The method according to any one of claims 1 to 14, characterised in that the security paper sheet includes a number of individual ups, and at least a part of the equalizing elements are arranged with an elongate form at one or more edge centres of the individual ups.

16. A security paper sheet for the production of security documents or documents of value and the like, with at least one intaglio printing motif with a raised relief structure, characterised in that a plurality of equalizing elements produced in the intaglio print, distributed over the area of the secu-rity paper sheet, are produced with a raised relief structure for equalizing the profile of the security paper sheet.

17. The security paper sheet according to claim 16, characterised in that the equalizing elements are arranged outside of the intaglio printing motifs.

18. The security paper sheet according to claim 16 or 17, characterised in that the security paper sheet includes a number of individual ups, and the equalizing elements are arranged substantially uniformly within the indi-vidual ups.

19. The security paper sheet according any one of claims 16 to 18, charac-terised in that the security paper sheet includes a number of individual ups, and the equalizing elements are respectively arranged differently in different individual ups, and/or the equalizing elements in different individual ups respectively have a different shape.

20. The security paper sheet according to any one of claims 16 to 19, char-acterised in that the equalizing elements have soft edges with a slight slope.

21. The security paper sheet according to any one of claims 16 to 20, char-acterised in that the equalizing elements have rounded outline shapes, and are formed in particular as circles, ellipses or ovals.

22. The security paper sheet according to any one of claims 16 to 21, char-acterised in that the equalizing elements have a height of between 40 µm and 260 µm, preferably between 60 µm and 120 µm, and particularly preferably between 80 µm and 100µm.

23. The security paper sheet according to any one of claims 16 to 22, char-acterised in that the equalizing elements are formed as blind embossings.

24. The security paper sheet according to any one of claims 16 to 22, char-acterised in that the equalizing elements are printed ink-receptively.

25. A document of value, such as a bank note, identity card or the like, produced from a security paper sheet according to any of claims 1 to 24.

26. An intaglio printing plate for embossing a security paper sheet for security documents or documents of value having at least one engraved mo-tif in the form of a relief structure, characterised in that a plurality of equal-izing engraved elements distributed over the surface of the intaglio printing plate are provided with a relief structure for equalizing the profile of the se-curity paper sheet to be printed.

27. The intaglio printing plate according to claim 26, characterised in that the equalizing engraved elements are arranged outside of the engraved mo-tifs.

28. The intaglio printing plate according to claim 26 or 27, characterised in that the equalizing engraved elements have soft edges with a slight slope.

29. The intaglio printing plate according to any one of claims 26 to 28, characterised in that the equalizing engraved elements have rounded out-line shapes, and are formed in particular as circles, ellipses or ovals.

30. The intaglio printing plate according to any one of claims 26 to 29, characterised in that the equalizing engraved elements have an engraving depth of between 40 µm and 260 µm, preferably between 60 µm and 120 µm, and particularly preferably between 80 µm and 100 µm.