The invention relates to a chip that protects against counterfeiting security printing, especially for banknotes and other security printing (e.g. pre-numbered forms), enabling the verification of the authenticity of a document.
Security printing is a type of printing, the execution of which by unauthorised persons is hampered by deliberate application of safeguards by which the safety of legitimate users is ensured. Used securities in varying degrees can protect against certain forms of counterfeiting. Securities, banknotes or important documents sometimes have a number of different security features difficult enough to falsify so that they are called highly protected prints.
There are three levels of security:
Banknotes have securities to protect against counterfeiting and thus belong to the group of security printing. The most widely used securities are:
In addition, part of banknote security is kept secret and is a strict secret data of the central banks issuing banknotes.
Due to the continuous development of counterfeiting techniques a constant search for new methods of document protection against illegal copying is needed. The aim of the present invention is therefore to provide a new kind of security.
These and other features and advantages of the present invention will be appreciated from review of the following Detailed Description of the Preferred Embodiments, along with the accompanying figures in which like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings.
It will be recognized that some or all of the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown. The Figures are provided for the purpose of illustrating one or more embodiments of the invention with the explicit understanding that they will not be used to limit the scope or the meaning of the claims.
This objective was achieved through the use of graphene quantum dots (Graphene Quantum Dot, GQD).
Quantum dots (QD) are semiconductor nanocrystals with sizes ranging from 2-10 nanometers (“nm”). They are a very specific type of substance with properties intermediate between semiconductors and quantum particles. A limited number of atoms and a diameter of a few nanometres gives the quantum dots unique properties of absorption and emission of radiation, which result from the presence of the effect of the quantum limit (quantum confinement effect). This means that the excitation energy emitted by the photons will depend on the composition of the crystal and its size. Similar to semiconductors, quantum dots absorb photons of light with such energy that the ability to transfer electrons from a non-activated state to a state of a higher available energy level. In addition, there is an emission process, because the wavelength emitted by light depends on the size of the dots. Hence, having a semiconductive material can produce markers having different colours, which are characteristic of quantum dots.
Nanoparticles with a small diameter core (2 nm) have fluorescence at a wavelength corresponding to blue light and even ultraviolet radiation (UV). When the diameter of the quantum dot core increases, the wavelength of the radiation emitted by the visible light increases, up to infrared radiation (IR). By modifying the composition and choosing the size of the nanocrystals, fluorescence in the full spectrum from ultraviolet (UV) to the infrared (IR) is obtained.
The radiation may be absorbed by quantum dots in a broad spectrum (
Graphene quantum dots (GQD) can also be prepared from graphite carbon fibers. This was successfully done with acids and chemical exfoliation (
Graphene quantum dots are stable because the level of luminescence (that is, they are resistant to photobleaching).
The invention relates to a security element against counterfeiting, in particular banknotes, comprising at least one graphene quantum dot (GQD) that is a graphene nanoparticle with a diameter of from 0.5 nm to 60 nm, preferably from 1 nm to 11 nm, containing from 1 to 90, preferably from 1 to 20 layers of graphene disposed in the flexible layer of graphene nanocomposite material, wherein the elastic layer of graphene nanocomposite material comprises at least one graphene layer disposed on the adhesive layer, preferably a polymer.
Preferably, the security element comprises graphene quantum dots (GQDs) of different sizes.
Preferably at least one quantum dot (GQD), preferably all quantum dots (GQDs) are an integral part of the flexible layer of graphene nanocomposite material.
Graphene in the security element is in a pure or doped form.
Preferably, the security feature comprises a layer of graphene, and two adhesive layers, wherein the graphene layer is located directly between the two layers of adhesive.
The invention also includes the use of the security feature according to the invention for securing banknotes, holograms, documents, passports, credit cards, excise bands, excise forms, personal identifiers, certificates or product labels.
The invention is further a system for checking the authenticity of security printing, in particular banknotes, comprising:
The invention also applies to a method for checking the authenticity of security printing, in particular banknotes, characterized in that the system is used according to the invention.
The security feature is made of nanocomposite, one of whose components is a binder, preferably a polymer, which ensures its integrity, hardness, flexibility and resistance to compression, and the other is the second layer of plotted quantum dots (GQDs). Flexible nanocomposite material is a material of heterogeneous structure composed of two or more components with different properties. The properties of the composites are not the sum or average of the properties of its components, and the material used in its construction exhibits anisotropy of physical properties.
The security feature is made of a composite material resistant to:
The mere presence of the structure of the graphene in a protected document is an additional security factor, as commercial production of graphene in the form of a single structure is not yet available to potential counterfeiters.
A security feature is one of the layers of security printing (3). The security feature (1) in the above example is not an integral part of other securities and may, but does not need to be placed in the same layer as other securities such as a hologram.
The presented security is a separate solution, not interfering directly with any other group of the above mentioned securities.
The security feature (1) based on the modification technology is not limited by current layout, shape and size. It does not require a constant power source. But dedicated devices by which detection is carried out (5) require it.
The structure of the nanocomposite material (2) of the security feature (1) takes into account:
Security feature (1) designed with quantum dots (GQDs) will be unique for each security printing (3). After treatment with a source of radiation (4), it starts to emit light in adequate band characteristics. The luminescent effect will then be identified by the assigned detection device (5), verified and compared with the standard base (6), followed by a confirmation or denial of compliance.
Other examples of the use of the security chip (1) are authentication of pre-numbered documents, such as: