WO2004087437A1

WO2004087437A1 - Safety marking

Info

Publication number: WO2004087437A1
Application number: PCT/CH2004/000211
Authority: WO
Inventors: Klaus Franken
Original assignee: Landqart
Priority date: 2003-04-04
Filing date: 2004-04-02
Publication date: 2004-10-14
Also published as: EP1610958A1; DE502004003766D1; EP1610958B1; MA27639A1; EA007846B1; ATE361844T1; EA200501385A1

Abstract

The invention relates to a safety marking (2,3; 5-7, 9) having a superficial color application (2, 3) containing iridescent pigments, wherein the color of said marking changes when the viewing angle is changed. Increased anti-forgery safety is achieved in said marking in that an additional safety element (5-7, 9) that is particularly variable optically is arranged in an at least partially overlapping area or in an area that substantially borders directly with the color application (2, 3).

Description

DESCRIPTION

TITLE security feature

TECHNICAL AREA

The present invention relates to a security feature with a superficial paint application containing iridescent pigments, which changes its color when the viewing angle changes. In addition, the present invention relates to security documents with such a security feature and methods for producing such security features or security documents.

STATE OF THE ART

The use of iridescent pigments as a surface coating in the simia of a print or a line is known per se and has already been used many times, in particular in the security field. Such applications have the advantage that they are practically invisible or only very weakly visible under direct supervision, and only develop their color effect when viewed from an oblique angle. They therefore do not interfere with the rest of the printing on the security paper and can be provided, for example, as a background or as areas arranged above the normal printing. They act as very efficient and at the same time comparatively inexpensive First stage security feature, ie as a security feature which can be easily recognized and verified by any user without the aid of electrical or electronic recognition devices. In particular, since such iridescent coatings can hardly be recognized or only very weakly under direct supervision, they can also not be reproduced in a simple copying process. On the contrary, such strips on documents, for example, lead to the area of the strip being printed on when copying the original document in direct supervision, if at all, is only very weakly recognizable, gives rise to a gray, unmistakable stripe during the copying process. Such an iridescent coating for a security document, such as a banknote, has already been described in FR-A-2429292.

PRESENTATION OF THE INVENTION

The invention is therefore based on the object of providing an iridescent security feature which is distinguished by increased counterfeit security, in particular as a first-stage security feature, and which can be produced at the same time in a cost-effective manner. It is about the improvement of a security feature with a superficial paint application containing iridescent pigments, which changes color when the viewing angle changes.

This object is achieved in that a further security element is arranged in at least partial overlap or essentially immediately adjacent to the paint application.

The essence of the invention thus consists in combining the iridescent security feature with a further, different type of security element in at least an adjacent, preferably overlapping manner. In particular, if an optically variable security element is used as a further security element, as is known in specialist circles under the term OVD (Optically variable device), the effects of an iridescent strip in combination with the OVD can become too strong increased security level give cause, since the two security features show different effects from different viewing angles. The optical flip-flop effect that occurs due to the combination of the iridescent security feature with the additional security element is, on the one hand, much more difficult, if at all, to copy, and on the other hand, it is also very easy for the user to verify. The increase in the security level also results from a manufacturing point of view, since an iridescent layer can typically be produced in a printing or coating process, while special machines must be provided for the application of an OVD. The necessary combination of these two methods alone increases the security level.

The further security element can be a diffractive element, particularly preferably selected from the group 2D holograms or 3D holograms, dot matrix elements, or the like. The corresponding optical gratings are e.g. manufactured by laser or electron beam technology. With regard to such elements, reference is hereby explicitly made to the following article: "Optical Document Security", Rudolph L. van Renesse (ed.), ArtechHouse Publishers, 1998, Boston / London, ISBN 0-89006-982-4.

However, the security element does not necessarily have to be an OVD, but can also consist of a metallic material in a fine chasing, a fine pattern of characters, lines, in other words, the further security element can be at least partially by a fine structure, in particular on a metallic basis be formed. Such a fine structure in combination with the iridescent coating leads to surprising optical effects, and has not been taken into account anyway, since it was previously considered impossible to apply such a fine structure to a layer of iridescent pigment in such a way that it could, for example, withstand mechanical loads would have grown in the area of banknotes.

The present combination can be used particularly advantageously when different, simultaneously recognizable surface areas are provided with color applications which contain different iridescent pigments, and which when viewed have a different color from at least one oblique viewing angle. Such a combination is described in EP 0490825 AI, and the disclosure content of this document is hereby fully included in the disclosure of this document. Such a combination of different color applications can have a particularly efficient effect if these color applications or the surface areas of these color applications are directly adjacent to one another. For example, it is possible to arrange stripes of different colors directly adjacent to one another on a document.

The further security element can be applied to the iridescent layer in a particularly stable and wear-resistant manner by the further

Security element has, at least in some areas, a carrier film which is at least partially provided with a structured metallization (e.g. a demetallized film or one embossed with a metallization in the form of the structure

Foil). This structured metallization can now constitute the aforementioned fine structure or the diffraction grating of an OVD, and accordingly it can

Fine structure or the diffraction grating by connecting them to the

Carrier film can be stabilized. Such a carrier film is applied to the paint application, for example, by means of a thermally activated adhesive. In other words, the further security element can be applied to a substrate in a hot stamping process.

Problematic u. When applying the additional security element to an iridescent layer, it may be that the thermally activatable adhesive with the very special surface with the iridescent layer does not ensure a permanent and strong connection. Accordingly, in this situation either the adhesive must be adapted to the specific surface conditions of the iridescent layer, which can be done, for example, by designing the thermally activated adhesive for more polar surfaces. Alternatively or additionally, it is also possible to modify the paint application superficially in order to adhere the additional security element to the paint application. This can be done either via a surface modification of a physical or chemical type, which is the uppermost Molelcülschichten of the paint application changed in such a way that the adhesive can then build a stable bond. A corresponding treatment with reactive chemicals or a plasma surface treatment is possible, for example. Alternatively or in addition, the modification can consist in providing a primer layer on the paint application, this primer layer particularly preferably having a polar character in order to be better adapted to typical thermo-activatable adhesives. Such a primer layer can be selected, for example, from the group of polyvinyl alcohol, polyacrylate, styrene-acrylic-based copolymers.

In order to support good adhesion between the further security element and the iridescent paint application from the beginning, the paint application should preferably be based on an aqueous solution of an iridescent pigment.

Advantageously, the further security element completely covers the paint application. For example, the color application can first be applied to the unmasked paper, and then the OVD can be glued on using hot stamping. The optical effect of such a complete overlap of the two security elements (iridescent element and further security element) is surprisingly striking. In this context, it is particularly advantageous if recognizable, adjoining surface areas are provided with color applications which contain different iridescent pigments and which have a different color when viewed from at least one narrow viewing angle area (cf. EP 490825 mentioned above), the further Security element at least partially covers both surface areas. The color transition between the surface areas can be fluid or sharp.

The color applications can be strips with a width in the range from 0.3 cm to 5 cm, but preferably from about 0.5 to 1.6 cm. This dimensioning is particularly suitable in connection with typical OVDs known from the security field, which have similar dimensions.

A particularly preferred iridescent pigment consists of mica platelets which are coated with a layer of a metal oxide, preferably Ti0 ₂ or iron oxide. Such iridescent pigments are, for example, from Merck under the trade name Iriodin (TM) available.

Further preferred embodiments of the security feature are described in the dependent claims.

In addition, the present invention relates to a security paper or generally a security substrate (which can consist, for example, of paper, but alternatively also of a plastic film or another carrier) for security documents such as banknotes, passports, certificates, etc., as well as packaging material, binding material, or the like Security feature as described above. The security feature is applied to the substrate, particularly preferably a paper carrier based on banknote paper with a high cotton content, or a substrate in the form of wood-free paper.

Furthermore, the present invention relates to a method for applying a security feature, as described above, which is characterized in that the iridescent pigments are worked up with transparent binders to give coating colors or printing inks, and in that the iridescent paint application is applied to a substrate in a printing or coating process is then, or subsequently, the further security element is applied to the substrate, possibly in register. The further security element is preferably at least partially applied to the iridescent ink application in a hot stamping process, particularly preferably with the deduction of a film. In order to ensure particularly good adhesion between the security element and the iridescent paint application, the iridescent paint application is preferably surface-modified before the further security element is applied, in particular by applying a coating, preferably a primer layer, to the iridescent paint application.

A first preferred embodiment of the method according to the invention is characterized in that the iridescent paint application is carried out with an aqueous solution, using binder, and the dry weight ratio of binder to pigment is in the range from 1.5 to 6, preferably in the range from 2 to 5.5. The ratio of dry binder to water in one is preferred Range from 1: 2 to 1: 3 set. Different binders suitable for printing inks or coating colors are suitable as binders. For example, a binder based on a modified styrene-acrylate copolymer emulsion is possible. This is preferably in combination with an iridescent pigment based on mica platelets, which are provided with a layer of a metal oxide, preferably Ti0 ₂ (for example Iriodin from Merck), and which in particular have an average size in the range of 10-60 μm. Here, for. B. from the binder used 50 to 60 g dry weight to 10 to 30 g iridescent pigment and 120 to 190 grams of water. It is possible to apply the ink on a sweet egg machine and / or in a printing machine, particularly preferably in a flexographic, gravure, screen printing or offset printing process.

Further preferred embodiments of the method according to the invention are described in the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

The invention will be explained in more detail below using exemplary embodiments in conjunction with the drawings. Show it:

Figure 1 is a plan view of a substrate with security features. and

Fig. 2 shows a section through ^' a typical material for the application of optically variable security features.

WAYS OF IMPLEMENTING THE INVENTION FIG. 1 shows a plan view of a substrate 1, which at the same time represents various exemplary embodiments of the security feature according to the invention. The substrate 1 can be a paper web, such as is used for the production of banknotes. Such paper is more special Structure and contains a high proportion of cotton fibers. However, the substrate 1 can also be a conventional paper web, with typical basis weights in the range from, for example, 50 to 150 g / m ^{2 being} possible. Instead of the paper web, the substrate 1 can also be designed as a plastic film, such a plastic film being made of polyamide, polyethylene, polypropylene, etc., for example. Likewise conceivable are substrates which consist of laminates of paper and plastic, for example of paper and a thermoplastic, or also laminates of different plastics with different properties in the individual layers. In this specific case 2, strips 2, 3 of iridescent color are arranged directly next to one another on the substrate 1. The two strips 2 and 3 have a different color, for. B. red and blue. Such an arrangement is known, for example, from EP 0490825, the disclosure content of which is hereby included. The two strips 2 and 3 adjoin each other to form a sharp edge. The strips 2 and 3 can be applied to the substrate 1 at the same time or in succession, in a coating process or in a printing process, gravure printing or flexographic printing, but also offset printing, can be used.

The iridescent strips are applied in an aqueous formulation that contains binders and the iridescent pigment. Additives may also be present. Possible formulations of the coating recipe or the printing recipe are given in Table 1:

Table 1

% FK stands for the solids content in percent.

The following about the individual components used:

Texicryl is a modified styrene acrylate copolymer emulsion and is available, for example, from ScottBader Ltd., Wollaston, Wellingborough, Northamptonshire, UK. Texiciyl 13-567 is an emulsion with a viscosity in the range of 150 to 200 mPas, a density of 1.09 g / ml and a pH of 8-8.8 at 25 degrees Celsius. Texicryl 13-804 is also a corresponding emulsion "with a viscosity 0 in the range of 500-800 mPa s, a density of 1.05 g / ml at 25 degrees Celsius and a pH value of 7.4-8.

Texanol is a 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and is an additive especially for latex paints. It serves for the fusion of the binder after the evaporation of the water serving as solvent. Texanol is available from 5 Eastman Chemical Company, Kingsport, US. Sterocoll D is a dispersion of an acrylic copolymer that contains carboxyl groups. It is used to change the viscosity of the entire solution. It is available, for example, from BASF, DE.

Cognis DSX 3116 is also a rheological additive and based on polyurethane. It is available, for example, from IMPAG Chemie Import AG, Zurich, CH.

Aquacer 531 is a wax additive for paints and printing inks. It is available from Byk-Chemie GmbH, Wesel, DE.

Nopco NM-305 is a defoaming agent that does not work on the basis of silicone, but on the basis of hydrophobic particles and fatty acid derivatives of paraffinic hydrocarbons. It is available, for example, from Nopco Paper Technology GmbH, DE.

Iriodin is an iridescent pigment based on mica platelets, which are coated with a titanium dioxide layer or with an iron oxide layer. These are so-called pearlescent pigments. They have an average grain size in the range of 10-60 μm. They are available from MERCK (Schweiz) AG, Dietikon, CH. Specifically, the following pigments are used: Modin ^® 205 rutile brilliant yellow (item no. 104285), 215 rutile pearl red (item no. 104792), 217, rutile pearl copper (item no. 104286), 219 rutile pearl purple (item no. 104287), 225 rutile pearl blue (Art. No. 104288), 235 rutile pearl green (Art. No. 104289).

1 shows how a further security element 5, in the specific case it is an optically variable security feature (OVD), is applied to the strips 2 and 3, the OVD partially overlapping both strips. The optical effects that can be achieved in this way are particularly salient. However, as shown in case 6, the OVD can also cover one of the strips and only partially cover them, or, as shown in case 9, can be arranged within a strip 3. Alternatively, it is also possible to arrange the OVD in a recess 8 in one or both of the strips 2, 3. It is essential that from the eye both the optical effects of the stripes and the OVD can be perceived, and so the increased security level can be achieved.

The OVD 5-7, 9 is, for example, a dot matrix element or a hologram. Such elements are available, for example, from Hologram Industries, FR. They can have different shapes, as shown in FIG. 1, and can be of different complexity.

Such OVDs are typically applied to substrates in a hot stamping process. Since the corresponding thermally activated adhesives usually do not develop sufficient adhesion on strips 2 and 3, a primer layer is applied to the strips, at least in the area of the arrangement of elements 5-7.9, which acts as an adhesion promoter. In particular, the adhesion promoter should lead to the modification of the generally rather apolar surface of the strips in such a way that the tendentially polar adhesive can adhere better. Alternatively, the adhesive can of course also be set accordingly. 2 now shows a laminate of the type that can be used, for example, when applying such OVDs. Similar laminates are described for example in US 6,280,891 and corresponding grids in US 2002/0164456 AI. They have a bottom layer of a thermoplastic adhesive 15. A metallization 14 is arranged above it, which has a corresponding structure, possibly supplemented by a reflection layer. The metallization can consist of gold, silver or aluminum. In the case of a hologram or dot matrix element, this structure is a diffraction grating, but it is also possible for the structure to be designed simply as a fine structure or pattern. A carrier film or protective film 13 is arranged over this layer 14, which in turn is covered by a lacquer layer 12. The sandwich 18 from the layers 12-15 remains on the substrate after appropriate application, while the layers to be described now only serve for feeding and are removed after application. An adhesive layer 11, which is designed as a release layer, ie as a separating layer, is arranged above the lacquer layer 12. This in turn is covered by a film 10. The material is fed as shown in Fig. 2, and at the separation point shown by the arrow 16, the lower part 18 is separated from the upper part 17, the upper part being removed in the machine, and the lower part, optionally in sections the substrate remains. A machine which is suitable for such a hot stamping process is, for example, the Foiljet machine available from Steuer, DE. The substrate and laminate are gem. Fig. 2 merged between two cylinders with an accuracy of substrate tuning

1 and laminate of <0.2mm adjusted (register accuracy). One of the cylinders can be designed as a matrix and the second simply as an impression cylinder, but it is also possible to design the two cylinders as a matrix and a male.

Typically, an embossing temperature is set in the range from 80-270 degrees Celsius, preferably from 220 to 250 degrees Celsius. As a result of the special adhesion conditions on a layer 2 or 3, the release ability of layer 11 must be carefully adjusted. This can also be achieved via the structure of the lacquer layer 12, for example via a smooth varnish.

LIST OF REFERENCE NUMBERS

1 substrate, paper balx, banknote

2 first iridescent stripe 3 second iridescent stripe

5-7.9 optically variable security features (OVD)

10 film, carrier

11 adhesive layer (release layer)

12 lacquer layer 13 carrier film

14 metallization (structured if necessary)

15 adhesive

16 separation point

17 removed web 18 remaining part on the substrate

Claims

Security feature (2,3; 5-7,9) with a superficial paint application (2,3) containing iridescent pigments, which changes color when the viewing angle changes, characterized in that there is at least partial overlap or essentially immediate bordering a further security element (5-7.9) is arranged on the paint application (2, 3).

2. Security feature according to claim 1, characterized in that different, at the same time recognizable surface areas (2, 3) are provided with color applications which contain different iridescent pigments and which have a different color when viewed from at least one oblique viewing angle area, the

Surface areas (2, 3) are particularly preferably formed directly adjacent to one another.

3. Security feature according to one of the preceding claims, characterized in that the security element is an optically variable

Security element (5-7.9) acts.

4. Security feature according to one of the preceding claims, characterized in that the further security element (5-7,9) is at least partially formed by a fine structure, in particular on a metallic basis.

5. Security feature according to one of the preceding claims, characterized in that the further security element (5-7.9) is a diffractive element, particularly preferably selected from the group 2D or 3D hologram, dot matrix element.

6. Security feature according to one of the preceding claims, characterized in that the further security element (5-7,9) at least in regions has a carrier film (13) which is at least in regions provided with a structured metallization.

7. Security feature according to claim 6, characterized in that the further security element (5-7.9) is applied to the paint application (2, 3) via an adhesive (15), in particular via an adhesive which can then be activated by radioactivity (15).

8. Security feature according to one of claims 6 or 7, characterized in that the paint application (2, 3) is provided with a superficial primer layer for the purpose of adhesion of the further security element (5-7.9) on the paint application (2, 3), wherein this primer layer particularly preferably has a polar character and can be selected, for example, from the group of polyvinyl alcohol, polyacrylate, styrene-acrylic-based copolymers.

9. Security feature according to one of the preceding claims, characterized in that the color application (2, 3) is based on an aqueous solution of an iridescent pigment.

10. Security feature according to one of the preceding claims, characterized in that the further security element (5-7.9) completely covers the paint application (2,3).

11. Security feature according to spoke 10, characterized in that at the same time recognizable, adjoining surface areas (2, 3) are provided with color applications which contain different iridescent pigments and which have a different color when viewed from at least one oblique viewing angle area, the further security element (5-7,9) at least partially covers both surface areas (2, 3), the color transition between the surface areas (2, 3) particularly preferably being smooth or sharp.

12. Security feature according to one of the preceding claims, characterized in that the color applications (2, 3) are strips with a width in the range from 0.3 cm to 5 cm, but preferably from about 0.5 to 1.6 centimeters.

13. Security feature according to one of the preceding claims, characterized in that the iridescent pigment is mica platelets which are coated with a layer of a metal oxide, preferably Ti0 ₂ .

14. Security paper for security documents such as banknotes, passports, certificates, etc. as well as packaging material, binding material, or the like, comprising a security feature according to one of the preceding claims, which is applied to a substrate (1), in particular a paper carrier.

15. A method for applying a security feature according to any one of claims 1-13, characterized in that the iridescent pigments are worked up with transparent binders to give coating colors or printing inks and that the iridescent paint application (2, 3) is applied to a substrate (1) in a printing or coating process, with the further security element (5-7, 9) subsequently or previously on the substrate (1), possibly in register , is applied.

16. The method as claimed in claim 15, characterized in that the further security element (5-7.9) is at least partially applied to the iridescent ink application (2,3) in a hot stamping process, particularly preferably with the deduction of a carrier (10).

17. The method according to claim 16, characterized in that before the application of the further security element (5-7.9) the iridescent paint application (2,3) is surface-modified, in particular by the iridescent

Color application (2,3) a coating, preferably a primer layer, is applied.

18. The method according to one of the claims 15 to 17, characterized in that the iridescent paint application (2, 3) is carried out with an aqueous solution using binder, and the dry weight ratio of binder to pigment is in the range from 1.5 to 6, preferably in Range is from 2 to 5.5, wob.ei particularly preferably the ratio of dry binder to water is set in a range from 1: 2 to 1: 3.

19. Process according to Anspmch 18, characterized in that a binder based on a modified styrene-acrylate copolymer emulsion and an iridescent pigment based on mica platelets, which are provided with a layer of a metal oxide, preferably Ti0 ₂ , and which in particular have an average size have in the range of 10-60 microns is used, preferably 50 to 60 grams of the binder Dry weight to 10 to 30 g of iridescent pigment and 120 to 190 g of water can be used.

20. The method according to one of the claims 15 to 19, characterized in that the ink application (2, 3) is applied to a coating machine and / or in a drawer machine, particularly preferably in a flexographic, deep printing, screen printing or offset printing method ,