WO2015163788A1

WO2015163788A1 - Multilayered product containing carrier with protective markings, and method for determining authenticity of product

Info

Publication number: WO2015163788A1
Application number: PCT/RU2015/000208
Authority: WO
Inventors: Аркадий Владимирович ТРАЧУК; Андрей Борисович КУРЯТНИКОВ; Игорь Васильевич ПАВЛОВ; Александр Игоревич МОЧАЛОВ; Алексей Витальевич САЛУНИН; Георгий Валентинович КОРНИЛОВ; Александр Михайлович ШИРИМОВ; Галина Сергеевна БАРАНОВА; Александра Александровна ТОРГАШОВА; Виктор Андреевич ВОРОБЬЕВ; Ошир Яизгилович МАНАШИРОВ; Николай Андреевич ШАВАРД; Юрий Алексеевич ПОРТНЯГИН
Original assignee: Федеральное Государственное Унитарное Предприятие "Гознак" (Фгуп "Гознак")
Priority date: 2014-04-23
Filing date: 2015-04-02
Publication date: 2015-10-29
Also published as: RU2567068C1

Abstract

The invention relates to the field of protecting products against counterfeiting and is intended for using an instrument for determining the authenticity of printed products to be protected, such as banknotes and securities forms, labels, excise stamps and postage stamps, payment and identification documents, and also passports and travel documents. The aim and technical solution of the proposed invention consist in creating a product containing a carrier with hidden security markings applied to the surface thereof, wherein the markings are carried out using a luminescent inorganic compound having a crystalline structure based on rare earth elements, characterized in being capable of Stokes or Anti-Stokes luminescence outside of the visible range of the optical spectrum, carried out under the influence of an excitation radiation which is within a first spectral range, and under a second influence on said luminescence by a stimulating radiation which is within a second spectral range, and characterized in that the intensity of the luminescence can change without changing the spectral composition thereof. The proposed technical solutions and methods for controlling authenticity provide for a high level of counterfeiting protection for a valuable document.

Description

MULTILAYERED PRODUCT CONTAINING A MEDIA WITH PROTECTIVE LABELING AND A METHOD FOR DETERMINING THE PRODUCT'S AUTHENTICITY

The invention relates to multilayer products from various materials using phosphors, including paper, polymer, and to the field of protection of products from counterfeiting and is intended for instrumental determination of the authenticity of protected printing products, such as banknotes and letterhead paper, labels, excise and postage stamps, payment and identification documents, as well as passports and travel documents.

State of the art

Recently, with increasing competition among manufacturers of security printing products, as well as a steady increase in the technical capabilities of potential counterfeiters, complex security features have become increasingly relevant. By such protective features it is customary to understand technical solutions in which, during instrument control, authenticity is checked not one but two or more parameters related in a specified way, or a certain reaction to two or more simultaneously specified actions is evaluated.

Examples of such parametric effects include the dependence of the UV luminescence of a substance on the temperature applied to it, or the angle of rotation of the plane of polarization of linearly polarized radiation under the influence of external electric field, or a reversible change in the color of a substance under the influence of heat and light.

The difficulty in creating such signs often lies in the need to reliably evaluate the parameters of interest of the sign under heterogeneous exposure under conditions of a limited time interval, or with a small content of the measured substance with the simultaneous presence of interfering factors (interference), i.e. with a small signal to noise ratio.

On the other hand, to complicate the chemical and / or elemental control of substances included in the protective label, it is necessary to minimize their weight (percentage) amount in the total composition. In addition, a frequent requirement for security features for instrument and machine authentication is their secrecy, that is, hardly detectable by generally accessible methods. In this regard, the practical interest in creating complex security features is primarily represented by solutions that do not exhibit their properties in the visible range of the spectrum, which significantly complicates the task.

These contradictions, and a wide range of generally available substances known from the prior art and available on the market, determine the need to search for and create new protective features of an integrated principle of action.

The proposed solution is based on the well-known physical phenomena of photostimulation (“flash”) and optical quenching of photoluminescence, which are fundamental in nature, and are described below.

Inorganic compounds having photostimulated quenching are known in the art. luminescence in the visible range of the spectrum. Examples of their compositions are shown in Table 1.

Table 1.

Of the compounds represented by the number of practically important compositions should include ZnS - Cu, Me, C1, where Me = Co ²⁺ extinguishing and Me = Pb ^2+, Sm ³⁺ or Mn ²⁺ flash. Studies of IR sensitivity spectra, flash spectra (green for Pb ²⁺ , red for Sm ³⁺ and orange for Mn ²⁺ ), as well as the kinetics of afterglow of visible luminescence showed that these compounds work according to the following scheme:

Cu afterglow quenching

- »Me + hv flash

where e _c is the electron in the conduction band, ap _v is the hole in the valence band. The amount of light accumulated in such luminescent compounds under optimal conditions of UV excitation reaches 10 ¹⁴ -10 ¹⁵ quanta-cm ^"2 , i.e., it is comparable with the total number of impurity centers at the penetration depth of the exciting radiation (- 50 μm for

= 365 nm and C _Cu ~ 3-10 ¹⁷ cm ^"3 ). At the same time, the efficiency of the luminescent compounds ZnS - Cu, Me, O is limited primarily by incomplete absorption of the recorded luminescent radiation, which is not more than 10-15%.

Thus, the currently known optically sensitive luminescent compounds based on zinc sulfide are designed to detect only quenching of visible luminescence when exposed to radiation in the region from 0.7 to 2.7 μm. The main disadvantage of these compounds, which completely excludes the possibility of their use as luminescent compounds with photostimulated quenching of luminescence upon excitation by radiation in the range from 0.7 to 2.7 μm and stimulation by UV radiation, is the absence of ions in their composition that provide, when excited by radiation in the range from 0.7 to 2.7 μm, Stokes or anti-Stokes IR luminescence in the specified area.

In this regard, to solve this problem, new classes of compounds have been developed that provide photostimulated quenching of the luminescence obtained by excitation in a given region of the spectrum due to radiation exposure in the wavelength range from 350 to 650 nm.

Let us consider the physical prerequisites for the possibility of synthesizing such luminescent compounds. The effect of optical quenching by infrared radiation of the visible luminescence of inorganic compounds based on zinc sulfide is explained in the literature on the basis of a simplified zone model. In such a RG model, luminescence quenching is associated with the release of holes with emission centers ionized by UV radiation into the valence band, followed by their nonradiative recombination at the emission centers formed by specially introduced impurity quenching ions. The situation basically remains the same if the quencher is not a hole trap, but a deep electron trap. Here the recombination interaction of impurity centers occurs, which usually have effective charges of opposite signs. A hole freed by thermal vibrations from the center of luminescence migrates to the quenching center that has captured the electron and recombines with it. In addition, small electron traps can play the role of quenching centers. With decreasing temperature, the time spent by electrons in them increases, and therefore the possibility of recombination of the latter with holes increases. The degree of quenching, that is, the fraction of nonradiative transitions, depends on the density of the excitation power. As in the case of the interaction of two luminescence centers, this is explained by the fact that with an increase in the intensity of the exciting radiation, the recombination rate grows faster (proportionally to N _a -n - where N _{a is the} number of ionized centers, n is the number of free electrons) than the rate of hole release from ionized centers extinguishing. As a result, the quenching effect changes. The degree of quenching also depends on the duration of the stimulating radiation pulses (τ). Obviously, if the pulse duration (τ) is less than the time of hole capture, on ionized centers of illumination, the holes will not have time to return to the above centers.

From the above it follows that the necessary conditions for the creation of luminescent compounds with photostimulated quenching (“modulation”) of luminescence when exposed to UV radiation in the wavelength range of 300-650 nm are as follows:

- the presence in the composition of compounds of rare-earth ions or their pairs (for example, Yb - Ho), which, when excited by laser radiation in the range from 370 to 1550 nm, provide Stokes and anti-Stokes IR luminescence in the region of 700 - 2500 nm;

the presence in the composition of compounds of ions forming donor levels in the band gap (deep electron traps) with a low probability of release of the electrons located on them. The formation of such traps can be achieved by partial heterovalent substitution of cations of the pigment matrix by other ions, which have a large electron capture cross section;

- the presence in the pigment of ions that form acceptor levels (deep hole traps) in the band gap of the pigment crystal. The formation of this type of traps can be achieved due to the partial heterovalent substitution of cations of the pigment matrix by other ions, which have a large hole capture cross section.

By selecting quenchers or sensitizers spatially located near the luminescence centers, it is possible to purposefully organize channels for selecting charge carriers from the luminescence centers or vice versa of the inflow. In both cases, modulation of stationary photoluminescence is observed. (negative - quenching, positive - synergistic flare-up). Moreover, when applying only electromagnetic oscillations corresponding to the frequency (wavelength), no change in the intensity of the luminescence signal is observed at all.

Using this approach, it is possible to synthesize luminescent compounds with modulation of stationary Stokes and anti-Stokes luminescence based on inorganic substances - sulfides, oxides, oxysulfides, phosphates, composite compounds of alkaline-earth, rare-earth elements having both a recombination and intracenter luminescence mechanism.

The prior art solution is US 43871 12 A, describing a technical solution that uses for instrument control the authenticity of valuable documents inorganic luminescent compounds with rare earth ions having anti-Stokes luminescence in the visible spectrum.

At the present stage, this solution does not provide the necessary level of security due to the availability of these luminescent compounds in the free market. Also, this solution does not have the property of changing the intensity of luminescent radiation when exposed to stimulating radiation.

Also known is the solution US 4047033 A, which describes a technical solution for instrument control of the authenticity of a valuable document based on the use of inorganic compounds with rare earth ions based on the Sr S compound having flash (photostimulated) luminescence in the visible optical spectrum.

This solution relies on luminescent compounds widely known in the art. Him a significant drawback is the use of the visible range of the spectrum when registering a sign.

Closest to the proposed invention is a method of protecting documents, securities or products using nanodiamonds with active NV centers. This solution is based on the use of complex effects - changes in the intensity of photoluminescence under the influence of the microwave field (RU 2357866).

The disadvantage of this method is the intrinsic photoluminescence of nanodiamonds in the visible spectrum, and the depth of modulation of its intensity by the microwave field is small, which requires the use of highly sensitive methods of analysis, high concentrations of the substance and exposure to the document by intense fields.

Disclosure of invention

The objective of the proposed invention is to increase the level of security, providing the possibility of expert or machine determination of the authenticity of the product based on the use of the security feature of the integrated principle of operation.

The problem is solved through the use of inorganic luminescent compounds not known from the prior art, as well as the use as a luminescence region of the spectral ranges lying outside the visible range of the spectrum (UV, or IR ranges).

Protective marking can be performed using a luminescent inorganic compound with a crystalline structure based on rare-earth elements, characterized by the ability to Stokes or anti-Stokes luminescence outside the visible range of the optical spectrum, which is carried out under the influence of exciting radiation lying in the first spectral range, and modulation of the indicated luminescence by stimulating radiation lying in the second spectral range, and modulation occurs without changing the spectral composition of the initial luminescent radiation.

The particle size of the inorganic luminescent compound is preferably from 0.01 μm to 100 μm.

The product is characterized by the fact that when at least one part of the surface of the protective marking is exposed to modulating radiation, the luminescence intensity, the rate of ignition and attenuation of the spectral bands of luminescence reversibly change.

The product can be made in the form of a banknote, excise stamp, postage stamp, passport, travel document, driver’s license, identity card, security, plastic card, label, payment document.

Protective marking can be performed on the surface of the medium by printing, for example, offset or metallographic printing.

Protective marking can be introduced into the paper or polymer mass, or into the surface layer of paper or polymer, or applied as an adhesive layer between the inner layers of the multilayer product.

Protective marking is preferably made in the form of geometric figures, guilloche elements, graphic or alphanumeric characters.

The problem is also solved by the described method for determining the authenticity of the product, 00208

10

described above, which consists in the fact that they produce constant excitation radiation in the first spectral band, the luminescence level is fixed, then they produce constant stimulating radiation in the second spectral band, and the change in the intensity of the luminescent radiation under the influence of stimulating radiation is recorded.

A method for determining the authenticity of the product is described, which consists in the fact that they produce pulsed or variable excitation radiation in the first spectral band, fix the intensity of the luminescent radiation in the phase of ignition or attenuation, produce stimulating radiation in the second spectral band, record the change in the intensity of luminescent radiation in the phase of ignition or attenuation.

A method for determining the authenticity of an article is also described, which consists in the fact that they produce pulsed or variable exciting radiation in the first spectral band, fix the temporal parameters of luminescence in the phase of acceleration or attenuation, produce stimulating radiation in the second spectral band, record the change in temporal parameters of luminescence in the phase acceleration or attenuation.

The problem is also solved by the method of determining the authenticity of the product, which consists in the fact that they produce exposure to exciting radiation in the first spectral band, and the change in the intensity of the exciting radiation over time is described by a harmonic function or the sum of harmonic functions, fix the change luminescence intensities, parameters proportional to the degree of distortion of the initial harmonic signal are calculated, the source of stimulating radiation in the second spectral band is turned on, and the change in parameter values is recorded.

The problem is also solved by the method of determining the authenticity of the product, which consists in the fact that they produce exposure to exciting radiation, sequentially change the wavelength of the stimulating radiation, fix the dependence of the intensity of the luminescent radiation on the wavelength of the stimulating radiation.

The problem is also solved by the method of determining the authenticity of the product, which consists in the fact that they stimulate the radiation in the first spectral band, fix the luminescence level, stimulate the radiation in the second spectral band, change the power of the stimulating radiation, and fix the dependence of the intensity of the luminescent radiation on the intensity of the stimulating radiation.

The advantages of the proposed invention are based on the use of a complex feature of authenticity, consisting in a certain reaction to a double exposure to the material of the protective labeling, and not manifested in other generally available materials (imitators) known from the prior art.

Also in the field of instrument control for determining the authenticity of valuable documents of particular interest are technical solutions that can use certain information about the document being verified, and at the same time are not only unavailable potential counterfeiter, but hidden from the public.

If some non-random information is applied to the protective marking, it is necessary to ensure its safety at least during the period of authentication, and at most during the period of circulation of the product. In this regard, the most promising is the application of protective information, which is temporary in nature. For example, information can be applied to the product for use in a short period of time, that is, it is applied and stored on the product only during its verification cycle on a counting and sorting machine or at an ATM. After checking the information, it can naturally disappear, for example, collapse under the influence of environmental components (temperature, humidity, pressure, magnetic fields, light, etc.).

One of the options for implementing the proposed invention is to increase the level of security, providing the possibility of expert or machine authentication, with the possibility of multiple verification of the authenticity of the product, eliminating the inadvertent detection of hidden information between verification cycles.

The problem is solved by the method of authenticating the product, which consists in detecting changes in the luminescence intensity of the composite material in the areas of protective markings treated with stimulating radiation, and latent image and / or information thus applied are recorded.

The advantages of the proposed invention are based on the use of a complex feature of authenticity, consisting in a specific reaction to a double exposure to the material of the protective labeling, and not manifested in other generally available materials (imitators) known from the prior art.

An additional condition is the possibility of applying and reading hidden information, which is randomly generated, but appears and is read using double exposure directly in the process of machine control and, therefore, cannot be reproduced consciously.

The best example of carrying out the invention

Example 1

The product in the form of a banknote contains on the front side a colorless protective marking of a rectangular shape made by the offset printing method.

The protective marking contains 80% of the binder, and 20% of an inorganic luminescent compound based on yttrium oxysulfide activated by ytterbium and cerium in the form of particles ranging in size from 2 to 5 microns.

When processing areas of protective markings with exciting pulsed laser radiation in the range of 930 - 970 nm, the Stokes luminescence of ytterbium ions is observed in two main spectral bands in the range of 0.98 - 1.02 nm.

When the protective markings are exposed to stimulating radiation in the spectral range of 330–370 nm, optical quenching of the indicated luminescence is observed, the luminescence intensity changing according to a given law depending on the intensity of the stimulating radiation, and only the intensity of the spectral bands of luminescence, and not its spectral composition, changes. After removing stimulating UV radiation, the luminescence intensity is restored.

Thus, the totality of the measured parameters, including the luminescence spectrum, the dependence of the intensity of the spectral bands not only on the exciting, but also on the modulating radiation, can be instrumentally measured, and thus the authenticity of the banknote is established. Example 2

The product in the form of an excise stamp contains on the front side a colorless protective marking of a rectangular shape made by offset printing.

The protective marking contains 80% of a binder and 10% of an inorganic luminescent compound based on yttrium oxysulfide activated by holmium and cerium in the form of particles ranging in size from 1 to 3 microns.

When processing areas of protective markings with exciting pulsed laser radiation in the range of 930 - 970 nm, the Stokes luminescence of holmium ions is observed in the main spectral band of 1, 18 nm with a luminescence ignition rate characterized by a time constant of 1 ms.

When exposed to areas of protective markings with stimulating radiation in the spectral range 330 - 370 nm, optical quenching of the indicated luminescence is observed. In this case, only the intensity of the spectral band of the luminescence, and the speed of its acceleration and attenuation, but not its spectral composition, varies according to a given law depending on the intensity of the stimulating radiation.

After removing the stimulating UV radiation, the luminescence intensity is restored, the speed the spectral band acceleration and decay, characterized by the luminescence time constant, take the previously indicated initial value.

Thus, the totality of the measured parameters, including the luminescence spectrum, the dependence of the intensity of the spectral bands not only on the exciting, but also on the modulating radiation, as well as the change in the rate of rise and decay of the luminescence depending on the intensity of the modulating radiation, can be instrumentally measured, and thus established the authenticity of the product.

Example 3

A method for checking the authenticity of a product in the form of a banknote, which contains on the front side a colorless protective marking of a rectangular shape, made by the offset printing method.

When the protective marking surface is continuously treated with exciting pulsed laser radiation in the range of 930 - 970 nm, the Stokes luminescence of ytterbium ions is observed in two main spectral bands in the range of 0.98 - 1, 02 nm.

When selectively exposed to some areas of the protective markings with stimulating radiation in the spectral range 330 - 370 nm, optical quenching of the indicated luminescence is observed, the luminescence intensity changing according to a given law depending on the intensity of the stimulating radiation, and only the intensity changes spectral bands of luminescence, and not its spectral composition.

During selective exposure to stimulating radiation, a random code is generated on the marking surface, which can be read out in the process of determining the authenticity of a banknote.

After removing the stimulating UV radiation, the luminescence intensity is restored, and the applied random code is destroyed.

The described method for checking the authenticity of a banknote, including the application and reading of a random code due to exposure to a substance labeling with stimulating radiation and analysis, the set of measured parameters, including the luminescence spectrum, the dependence of the intensity of the spectral bands on the exciting and stimulating radiation, can be implemented instrumentally, and thus banknote authenticity can be established. Industrial applicability

The invention is applicable in the field of protection of products from counterfeiting and allows the manufacture of multilayer products from various materials using phosphors, including paper, polymer, as well as instrumental authentication of protected printing products, such as banknotes and letterhead paper, labels, excise and postal stamps, payment and identification documents, as well as passports and travel documents.

Claims

CLAIM

1. A multilayer product containing a carrier with a hidden protective marking deposited on its surface, and the marking is made using a luminescent inorganic compound with a crystalline structure based on rare earth elements, characterized by the ability to Stokes or anti-Stokes luminescence outside the visible range of the optical spectrum, carried out under the influence of the exciting radiation lying in a different second spectral range, and having the ability to a change in the intensity of said luminescence by stimulating radiation lying in the third spectral range, and characterized in that the change in luminescence intensity occurs without changing the spectral composition of its radiation, and when applied to the marking of stimulating radiation in the second spectral range, the luminescence intensity changes under the influence of exciting radiation in the first the spectral range is due to optical quenching of luminescent radiation or due to photos stimulation of luminescent radiation.

2. The product according to claim 1, characterized in that the particle size of the inorganic compound is from 0.01 μm to 100 μm.

3. The product according to any one of paragraphs. 1, 2, characterized in that it consists of a banknote, excise stamp, postage stamp, passport, travel document, driver’s license, identification card, security, plastic card, label, payment document.

4. The product according to p. 3, characterized in that the protective marking is made by the printing method.

5. The product according to claim 3, characterized in that the protective marking is introduced into the paper or polymer mass, or applied as a layer on the surface of the paper or polymer, or applied as an adhesive layer between the inner layers of the multilayer product.

6. The product according to p. 3, characterized in that the protective marking is made in the form of geometric figures, guilloche elements, graphic or alphanumeric characters.

7. The product according to claim 3, characterized in that the protective marking is made hidden and indistinguishable on the surface of the carrier when observing the reflection in the visible range under diffuse lighting.

8. The method of determining the authenticity of the product, which consists in the fact that they produce constant excitation radiation in the first spectral band, fix the luminescence level, then they produce constant stimulating radiation in the second spectral band, and record the change in the radiation intensity of the luminescent radiation under the influence of the exciting and stimulating radiation.

9. A method for determining the authenticity of a multilayer product according to claim 8, characterized in that it produces an effect of exciting radiation, sequentially changes the wavelength of stimulating radiation, fixes dependence of the luminescent radiation intensity on the wavelength of stimulating radiation.

10. The method of determining the authenticity of the product according to claim 8, characterized in that they produce stimulating radiation in the first spectral band, fix the luminescence level, produce stimulating radiation in the second spectral band, change the power of stimulating radiation, and fix the dependence of the intensity of luminescent radiation on the intensity of the stimulating radiation.

11. The method according to any one of paragraphs. 8 to 10, characterized in that a change in the luminescence intensity of the composite material is detected in the protective marking areas treated with stimulating radiation, and the latent image and / or information thus applied are recorded.

12. The method of determining the authenticity of the product is that they produce exposure to pulsed or variable excitation radiation in the first spectral band, fix the intensity of the luminescent radiation in the phase of acceleration or attenuation, produce exposure to pulsed or variable stimulating radiation in the second spectral band, and record the change in the intensity of the luminescent radiation in the phase of acceleration or attenuation.

13. The method of determining the authenticity of the product according to p. 12, characterized in that they produce exposure to pulsed exciting radiation in the first spectral band, fix the temporal parameters of luminescence in phase flare-up or decay, produce stimulating radiation in the second spectral band, record a change in the temporal parameters of luminescence in the flare-up or damping phase.

14. The method for determining the authenticity of the product according to p. 12, characterized in that it produces an excitation radiation in the first spectral band, wherein the change in the intensity of the excitation radiation in time is described by a harmonic function or the sum of harmonic functions, a change in the luminescence intensity is recorded, parameters proportional to the degree of distortion are calculated the initial harmonic signal, include a source of stimulating radiation in the second spectral band, fix the change in the values of the pairs ametres.

15. The method according to any one of paragraphs. 12-14, characterized in that a change in the luminescence intensity of the composite material is detected in the protective marking areas treated with stimulating radiation, and the latent image and / or information thus applied is recorded.