Background Art As is known, a problem that is currently strongly felt in various fields and particularly in the production of bank notes, security papers and documents in general, is preventing forgery of such documents; among the various known systems, the most widely used ones use security threads that can be inserted partially or fully in the paper, stripes that can be applied externally to one face of the document, and patches that are also placed on one face of the document.

These security elements generally have metallic, magnetic, microprinted, fluorescent threads, which mostly use a layer of aluminum deposited in vacuum, on which lettering is provided, for example by selective demetallization, and magnetic areas are provided being deposited in any manner.

There are also color elements, also variously distributed, which range from holography to color-changing pigments to dichroic techniques and so forth, in which the color variation depends on the variation of the incidence of the light that strikes them.

These solutions predominantly use metallized bands, which accordingly require a long operating sequence, since it is necessary to first metallize the band and then perform, on additional kinds of machines, all the treatments required, which range from demetallization for the lettering, to application of the magnetic material, to formation of the holograms.

Clearly, this approach leads to particularly high costs and is also not always able to provide optimum results as regards security.

Disclosure of the Invention

The aim of the present invention is to solve the problems cited above, by providing a security element for bank notes, security papers and documents in general that allows to combine security characteristics that can be detected immediately by the user with additional security characteristics that can be detected by an apparatus, without thereby having to resort to band metallization operations and the like.

Within this aim, an object of the invention is to provide a security element that can be produced by means of processes that can be performed in a single pass with very low costs.

Another object of the present invention is to provide a security element that allows to combine multiple security characteristics, consequently increasing the anti-forgery potential.

Another object of the present invention is to provide a security element for bank notes, security papers and documents in general that is simplified in its execution while providing the greatest assurances of reliability.

This aim and these and other objects that will become better apparent hereinafter are achieved by a security element for bank notes, security papers and documents in general, according to the invention, characterized in that it comprises at least two adjacent regions without metallic materials, one of said regions having a layer of material whose light refraction varies with the angle of incidence of the light, the other region having a layer of material having constant reflection, at least one of said regions forming areas without material in order to form graphic markings, characters and the like that can be detected visually.

Brief Description of the Drawings Further characteristics and advantages of the invention will become better apparent from the description of a preferred but not exclusive embodiment of a security element for bank notes, security papers and documents in general, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

Figure 1 is a plan view of the security element, shown schematically as a thread; Figure 2 is a sectional view, taken along the line II-II of Figure 1 ; Figure 3 is a sectional view, taken along the line 111-111 of Figure 1 ; and Figure 4 is a sectional view, taken along the line IV-IV of Figure 1.

Ways of carrying out the Invention With reference to the figures, the security element 1 for bank notes, security papers and documents in general, according to the invention, shown schematically in the accompanying drawings as a thread but equally providable as a stripe or patch, by using conventional techniques, generally comprises a backing layer 2, which is constituted for example by polyester and advantageously has, in a specific embodiment that must not be considered as limitative, a width of approximately 4 mm.

A first thermoadhesive layer, generally designated by the reference numeral 3, is provided on the lower face of the backing layer 2.

The particular feature of the invention consists in that on at least one of the faces of the backing layer 2 there are two regions without metallic materials, which are arranged adjacent.

In the specific example, the two regions, schematically designated by the reference numerals 10 and 11, are arranged longitudinally side by side, but they can be arranged adjacent in various manners, such as with a transverse alternation, a sequential alternation, or the like.

In the specific example, one of the regions, for example the one designated by the reference numeral 10, is provided by means of a layer of material whose light refraction varies according to the variation of the angle of incidence of the light.

According to a preferred but nonlimitative embodiment, said region is obtained by means of a holographic lacquer, over which an embossing is performed in order to impress the holographic image; to complete the assembly, a colored ink 15 is printed over the embossing.

Instead of holographic printing, it is possible to perform, by way of conventional methods, dichroic printing or the application of material that changes color according to the incidence of the light.

This solution allows to eliminate the typical vacuum-metallized backgrounds, which have a very high process cost, since the apparatus for performing such processes are very different because they comprise, for example, for the holographic threads, machines for spreading the holographic lacquer, then embossing machines and then metallizing machines and machines for finishing with protective lacquers, thermoadhesive materials, and the like.

In the case of dichroic threads, the prior art forces the use of vacuum vaporization systems in order to deposit, for example, magnesium fluoride, chromium and then aluminum.

The formation of metal-free regions allows to perform all the processes in a single pass.

The other region, i. e. , the region 11, is formed by applying a material that has constant reflection, such as for example an ink that can be of the same color as the ink used for printing over the embossing in the case of holographic printing, or of a different color.

Areas without material, i. e. , negative areas, designated by the reference numeral 20, are provided on one of the regions, in the specific example on the region 11, and allow to form graphic markings, characters and the like that can be detected visually.

These areas are spaced one another, and between two successive areas it is possible to apply magnetic codes, designated by the reference numeral 30, which are embedded in the layer of ink that constitutes the region 11.

Likewise, the areas without material may also optionally be provided in the color-changing region 10.

With the described solution it is possible to provide an innovative method for obtaining the security element, since it is possible to perform a single

pass by using any printing machine, such as for example a conventional rotogravure machine, which applies in succession the layer of material with light refraction that varies according to the angle of incidence of the light, and a subsequent section in which the layer of material with constant reflection is applied.

In the specific case of a layer of material with variable light refraction, produced by holography, there is a section in which the holographic lacquer is applied, followed by a section in which embossing is performed over the holographic lacquer in order to impress the holographic image, and by an additional section that applies a layer of colored ink over the embossing; then the material with constant reflection is applied by means of a normal printing technique.

To complete the assembly, in the case of threads, there is a protective layer 40 which is applied by optionally interposing an adhesive layer 41 which, for the sake of simplicity, is not shown in the drawings in the longitudinal cross-sections.

Furthermore, a second thermoadhesive layer 42 is provided externally.

It should be noted that if the security element is constituted by stripes or patches, the sequence of the layers is modified according to the different type of execution, without altering the concept of execution as regards the adjacent arrangement of the regions 10 and 11.

It should be added to the above that it is possible to apply semitransparent conducting substances, such as polyanilines, so as to give electrical conductivity properties to the security element.

It is also possible to spread optically transparent substances that can be detected by magnetoresistors or magnetic inductors or by magnetic resonance.

The regions bearing the layer of material whose light refraction varies according to the angle of incidence can be obtained by means of fluorescent inks, phosphorescent inks, inks with diversifiable infrared absorbance, and

these substances advantageously are not arranged at the areas without material.

Said areas without material can be obtained with any known method and can also be provided by means of a laser beam.

It is therefore evident from the above description that the invention achieves the intended aim and objects, and in particular the fact is stressed that a security element for bank notes, security papers and documents in general is provided which allows to produce at least two separate regions without metallic material that allow to achieve high security criteria while simplifying considerably all the steps of production, since the step of applying the metallic layer or of vacuum metallization is eliminated, and therefore color change characteristics are obtained which depend on the different coloring provided for the ink layer located in the color-changing region.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claim.

Furthermore, the individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other examples of embodiment.

Moreover, it is noted that anything found to be already known during the patenting process is understood not to be claimed and to be deleted from the claims.

The disclosures in Italian Patent Application No. MI20002A002489 from which this application claims priority are incorporated herein by reference.