WO2010151177A1

WO2010151177A1 - Optical security element, method for preparing same and method for verifying the authenticity of an object provided with such a security element

Info

Publication number: WO2010151177A1
Application number: PCT/RU2010/000354
Authority: WO
Inventors: Андрей Львович КАРАСЕВ
Original assignee: Открытое Акционерное Общество "Научно-Производственное Объединение "Криптен"
Priority date: 2009-06-25
Filing date: 2010-06-24
Publication date: 2010-12-29
Also published as: EA013395B1; EA200900975A1

Abstract

The invention relates to the field of protecting value documents against forgery and verifying the authenticity of such documents. In the production of a security element, latent images (2, 2') are printed on each side of a carrier (1) which is transparent in the visible and ultra violet regions of the spectrum, using a colourless liquid composition containing a UV absorber, the absorption spectrum long-wave limit of which is in the range of 370-400 nm on one side of the carrier and 270-360 nm on the other side of the carrier. The images are configured independently of each other and/or are in a given alignment so that they produce a complex image when rendered visible. The latent images are cured under temperature. A thin protective layer (3), which is transparent in the UV region of the spectrum, is applied to the carrier (1). The refractive index of the protective layer (3) coincides with the refractive index of the carrier (1) material and the latent images (2, 2'), thus ensuring that the formation edges of the latent images are invisible. The carrier (1) is incorporated in the form of a transparent window into the object requiring protection.

Description

OPTICAL PROTECTIVE ELEMENT, METHOD FOR ITS MANUFACTURE

AND METHOD FOR VERIFICATION OF AUTHENTICITY OF OBJECT WITH

INDICATED PROTECTIVE ELEMENT

FIELD OF THE INVENTION The invention relates to the field of protection against counterfeiting and authentication of valuable documents, in particular, to the manufacture and production of optical security elements carrying hidden images that are practically invisible in natural light to the naked eye and visualized when observed under special lighting conditions, for example, in UV, IR, polarized light or using a combination of several optical elements.

State of the art

The objective of the present invention is to provide a protective optical means with a high degree of protection against counterfeiting, which is also evidence of the authenticity of the protected object. At the same time, the protective feature is invisible in natural light to the naked eye and is visualized with high contrast when using a visualization device that is simple in design. Moreover, each protective element, which is a single-layer polymer film, can carry several different security features, which significantly increases the level of protection. The tool is designed to protect against counterfeiting and as a sign of authenticity of banknotes, passports and other valuable documents, plastic cards. The main way to use a protective tool is in the form of a transparent window in the protected object. Currently, for protection against counterfeiting and as authenticity signs of protected objects, special means of protection and authentication signs are used (in addition to various means of printing protection) built into the protected product in the form of a polymer transparent or translucent window that carries one or more security features, such as various visible images, a color-changing effect in transmitted and reflected light, diffraction, holographic and other optical effects. Among the protective elements with variable optical The most difficult to reproduce properties are elements containing latent images of various physical nature, visible only in certain lighting conditions or when using special devices. The concept of using hidden images in a transparent window of a valuable document, rendered separately, was first proposed in patent US 6124970 publ. 09/26/2000, MPKG02B 27/28. However, the described tool consists of three polymer layers, and has a significant thickness, which makes it impossible to use this tool as a window in a paper base.

In the international publication WO / 2007/137334, it is proposed to use liquid crystal layers to form a polarization structure — the structure is multilayer but thin enough, which makes it applicable as a transparent window carrying a hidden polarized image.

In the above-mentioned technical solutions known from the prior art, double polarized images are presented, which are technologically difficult to implement, with simple visualization using a single filter, which makes them insufficiently resistant to copying and imitation. The objective of the present invention is to develop a new type of security element used in the form of a transparent window in the protected object and presented in the form of a transparent polymer layer that carries at least two or more independent and / or coordinated latent images formed using the barrier properties of UV absorbers, and invisible in natural and ultraviolet light to the naked eye, while the protective element obtained in this way provides an increased level of protection, as well as the development of TCA process verifying the authenticity of an object with a security element obtained with providing hidden images with high contrast on screen luminous when irradiated with light in a predetermined wavelength range.

SUMMARY OF THE INVENTION According to a first aspect of the invention, a manufacturing method is provided. an optical security element used in the form of a transparent window in the protected object, which comprises the following steps: a) a carrier is transparent in the visible and ultraviolet regions of the spectrum; b) imprint the latent image on at least one portion of the carrier on one side using a colorless liquid composition containing a UV absorber with a red absorption spectrum at 370-400 nm; c) imprint the latent image on at least on one part of the carrier on the other hand using a colorless liquid composition containing a UV absorber with a red absorption spectrum in the range of 270-360 nm, so that latent images on both sides of the carrier are composed independently of each other and / or are in a predetermined coordinated position with respect to each other with the possibility of providing separate and / or combination of images for visualization, d) subjecting the latent image to curing at a temperature in the range of 70 ° -80 ° C. e) applying a thin protective layer transparent to UV region of the spectrum, on both sides of the carrier over the entire surface of the protective element, while the refractive index of the protective layer essentially coincides with the refractive index of the carrier material and latent images, providing gence boundaries forming latent images with the naked eye. f) embed the resulting media in the form of a transparent window into the protected object.

In the claimed method, a polymer film is used as a carrier.

According to a first aspect of the invention, the UV absorber is not capable of emitting light under the influence of UV light. According to a first aspect of the invention, the colorless liquid composition from which the latent image is formed comprises 0-10% polymer and 0.3-3% UV absorber; preferably 0-5% polymer and 0.5-1.5% UV absorber. Organic and inorganic substances having high extinction coefficients in the UV part of the spectrum are used as UV absorbers, and the position of the red border of the absorption spectrum is an essential protective feature. The red boundary is the long-wavelength boundary of the absorption spectrum: in the wavelength range shorter than the red boundary, the substance absorbs most of the radiation energy; in the wavelength range longer than the red boundary, the substance transmits most of the radiation energy. In this case, the UV absorber is inert with respect to UV light and does not exhibit photoemission of long-wave radiation under the influence of UV light in the range 200- ^ 00 nm.

As UV absorbers, compounds with high extinction coefficients are used, from the series: metal ions, organometallic compounds, liquid crystalline substances, benzoates, benzotriazoles. At the same time, the latent image is imprinted onto the medium by direct printing from a number of: flexographic printing, intaglio printing, screen printing.

In addition, the security element is formed in such a way that it is part of one of the protected objects: banknotes, passport pages or another valuable document, plastic card. According to a first aspect of the invention, the thin transparent protective layer is a mechanically strong lacquer coating with a thickness of about 1 μm.

According to a second aspect of the invention, there is provided an optical security element used in the form of a transparent window in a protected object, consisting of a polymeric carrier transparent in UV light, with hidden images applied to it by direct printing, obtained according to the method described above.

According to a third aspect of the invention, there is provided a method for verifying the authenticity of an object with a protective optical element, in which an object with a protective element, made according to the first aspect of the invention, is placed between a UV light source and a screen that fluoresces under the influence of UV light, wherein element UV light with a wavelength of 365 nm provides visualization on the specified screen only areas with a hidden image formed by a UV absorber with a red border of the absorption spectrum in the range of 370-400 nm; Irradiating the protective element with light with a wavelength of 254 nm provides visualization of areas with latent images formed by UV absorbers with a red border of absorption spectra in the ranges of 270-360 nm and with a red border of the absorption spectrum in the range of 370-400 nm, as a dark image on a luminous screen .

Thus, portions of the carrier sealed with a UV absorber do not transmit UV light, while the rest of the carrier is transparent to it by definition. As a result, a dark image of the areas of the carrier sealed with a UV absorber is obtained on the fluorescent screen, “UV shadow.” to.

As a rule, low-pressure mercury lamps of low pressure are used for verification, generating the most intense lines of the spectrum of emission of mercury - 254 and 365 nm. Using these lines separately allows for separate visualization of latent images in accordance with their red boundaries of the absorption spectrum.

In the claimed method, the screen is made of a material that scatters light, on one side of which, facing the UV light source, a layer of fluorescent coating is applied.

In addition, the protective element is formed in such a way that it can withstand temperatures of 180 ° C, since polymers that withstand short-term heating up to 180 ⁰ C are used as a carrier, UV absorbers that are stable at this temperature are used to form a latent image.

Description of the figures of the drawings

Signs, elements and advantages of the invention arise from the following description of embodiments of the invention with reference to the accompanying drawings, in which

Fig. L is a cross-sectional view of a security element carrying hidden invisible images. Figure 2 schematically shows the optical spectra of UV absorbers with different red boundaries of the absorption spectrum and the emission spectrum of a low-pressure mercury lamp.

Fig. 3 shows a diagram of an implementation of a method for verifying the authenticity of an object with a protective optical element using an appropriate verification device.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION A description of an optical security element and a method for its manufacture will be described with reference to FIG. 1-3. According to a method for manufacturing an optical security element on a carrier 1, which is a polymer film that is transparent in the visible and ultraviolet regions of the spectrum, latent images 2 and 2 'are imprinted on each of its sides, which are invisible in natural and UV light and visualized using a simple structurally the implementation of the device, which will be described below. Hidden images 2 and 2 ', which are separate characters (letters, numbers, logos, ornaments, etc.), are imprinted by direct printing using a colorless liquid composition containing a substance having a high absorption coefficient in the ultraviolet region of the spectrum - UV absorber. As the carrier material, polymers are selected that are transparent in the visible and UV spectral regions such as: polyethylene, polypropylene, other polyolefins, polyoxymethylene, polyvinyl alcohol, polyesters, cellulose hydrate and other cellulose derivatives.

The liquid colorless composition by which latent images are imprinted is a solution based on water or an organic solvent containing 0-10% (preferably 0-5%) of the corresponding polymer, or UV curable varnish containing

0.5-3% (preferably 0.3-1.5%) of the UV absorber.

As a UV absorber, from which latent images are also formed, metal ions are used that can form strong complexes with a polymer matrix, for example, copper (I) and (II), iron (III), some organometallic compounds, and also organic compounds from a number of benzoates or benzotriazoles. For example, the connection:

2,4-di-tert-butylphenyl-4'-hydroxy-3 ', 5'-di-tert-butylbenzoate, which is characterized by a red absorption spectrum border of about 350 nm, or a compound: 2- (2'-hydroxy-3' , 5'-di-tert-amylphenyl) benzotriazole, which is characterized by a red absorption spectrum border of about 400 nm.

It should be noted that the proposed security feature can be used in the security element in combination with other known security features, which further increases the level of protection and resistance against counterfeiting and copying. For example, a UV absorber, which is an integral part of a colorless liquid composition, can be of a liquid crystalline nature, in this case, a latent image formed using such a UV absorber carries two protective features - an ultraviolet shadow and a latent polarized image. To protect latent images from the external environment, to increase the mechanical strength and durability of the protective element, as well as to hide possible print traces, both its surfaces are coated with a thin protective layer 3, transparent in the visible and ultraviolet regions of the spectrum, having a refractive index close to the refractive indices of the carrier material and hidden images, which determines the invisibility of images when observed with the naked eye. In addition, the protective layer has high mechanical strength and protects the element from scratches and abrasion.

The visualization of latent images is based on the large difference between the optical densities in the UV range of the latent image sections formed by a layer of a UV absorber and an unsealed polymer carrier that practically does not absorb UV light.

In this case, the correlation between the absorption spectrum of the UV absorber and the emission spectrum of the UV light source, schematically shown in FIG. 2, is significant. As a rule, low-power low-pressure mercury lamps are used for verification, generating the most intense lines in the spectrum of mercury emission - 254 and 365 nm. For purposes for visualization of latent images, the Ultramag K-3 authenticity determinant lamp was selected, which allows each line to be used separately for testing. If the red border of the UV absorber forming the image lies in the region of 400 nm (A400 in FIG. 2), the imaging process does not require additional operations, since the sealed areas absorb all the light in the UV region up to 400 nm, and the unsealed areas of the carrier do not absorb this light. If the red border of the UV absorber forming the latent image lies in the region of 350 nm (A350 in FIG. 2), the latent image cannot be visualized with the full light of the lamp, since the sealed sections transmit light with a wavelength of 365 nm and do not create a shadow, t .e. the 365 nm line should be filtered, only then the image formed by the AZ 50 absorber will be visualized using the 254 nm line. If the red border of the UV absorber lies in the region of 250 nm. (A250 in FIG. 2), the latent image cannot be visualized with a low-pressure mercury lamp. It is necessary to use another light source, for example, a mercury-xenon lamp with a set of filter elements.

In addition, these correlations show that two different latent images formed by two UV absorbers with different red borders can be visualized sequentially. For example, image 2 is formed by the absorber A350, image 2 'is formed by the absorber A400. Illumination of the protective element with 365 nm light results in the visualization of only one image 2 'formed by the A400 absorber, image 2 does not appear, since the AZ 50 does not absorb 365 nm light; Illumination of the same element with 254nm light leads to the simultaneous visualization of both images 2 and 2 ', since 254nm light is completely absorbed by both absorbers forming these latent images. As can be seen from Figure 2, there are no fundamental restrictions on the number of latent images - everything is determined by the spectral characteristics of UV absorbers and the accuracy of the allocation of spectral bands of probe light; an acceptable number of images is three; a preferred number is two. Images can be independent or agreed upon by content, for example, a series (image 2) and a document number (image 2 '), or two halves numbers, or other similar things.

The ability to imprint in a transparent medium using UV absorbers several hidden images with sequential visualization enhances the degree of protection and resistance to copying and imitation of the proposed security element.

A method for verifying the authenticity of an object with a protective optical element according to the invention is disclosed with reference to FIGS. 2 and 3. According to this method, an object with a protective element is placed between a UV light source and a screen fluorescent under UV light, wherein the protective element is irradiated with UV light with a length 365 nm wavelengths provides visualization of only areas with a latent image formed by a UV absorber with a red absorption spectrum in the range of 370-400 nm, while the image with a red border in at 270-360 nm remains invisible; Irradiation of the protective element with light with a wavelength of 254 nm provides visualization of areas with latent images formed by UV absorbers with both the red border of the absorption spectra in the ranges 270-360 nm and the red border of the absorption spectrum in the range 370-400 nm, as a dark image on a luminous screen, since light with a wavelength of 254 nm is equally effectively absorbed by both absorbers, as shown in FIG.

The latent image is visualized using a device (Fig. H), consisting of a UV radiation source (designated as UV light in Fig. H), generating mercury lines 254 and 365 nm and a fluorescent screen 4: UV radiation passes through the sections almost without loss polymer carrier 1, unsealed by the UV absorber of the latent image, the protective layers 3, and reaches the screen 4, causing its fluorescence; UV radiation incident on parts of the latent image formed by the UV absorber does not reach screen 4 due to the almost complete absorption of the hidden image, therefore, these parts of the screen do not fluoresce, because are in the UV shadow - the result is a visible image 5 (UV shadow) - dark signs 5 of the image. Industrial applicability

The claimed invention can be used to protect against falsification of valuable documents: passports, vouchers, banknotes, stocks, check books and to identify the authenticity of these documents.

Claims

CLAIM

1. A method of manufacturing an optical security element used in the form of a transparent window in a protected object, which comprises the following steps: a) imprinting the latent image on at least one portion of the carrier spectrum that is transparent in the visible and ultraviolet regions on one side of it using a colorless liquid composition containing a UV absorber with a red border of the absorption spectrum in the region of 370-400 nm, b) imprint a latent image on at least one portion of the carrier on its other side using a colorless liquid composition containing a UV absorber with a red absorption spectrum border in the region of 270 - 360 nm, so that the latent images on both sides of the carrier are arranged independently of each other and / or are in a predetermined coordinated position relative to each other with the possibility of formation when rendering a complex image, c) subject the latent image to cure at a temperature in the range of 70-80 ° C. d) a thin protective layer is applied, transparent in the UV spectral region, on both sides of the carrier over the entire surface of the protective element, while the refractive index of the protective layer essentially coincides with the refractive index of the carrier material and latent images, ensuring the invisibility of the boundaries of the formation of latent images with the naked eye. f) embed the resulting medium in the form of a transparent window into the protected object.

2. The method according to p. 1, in which a polymer film is used as a carrier.

3. The method according to p. 1, in which compounds with a high extinction coefficient are used as UV absorbers from the series: metal ions, organometallic compounds, liquid crystalline substances, benzoates, benzotriazoles.

4. The method of claim 1, wherein the UV absorbers are not capable of emitting light. under the influence of UV light.

5. The method according to claim 1, wherein the colorless liquid composition contains 0-10% polymer and 0.3-3% UV absorber; preferably 0-5% polymer and 0.5-1.5% UV absorber.

6. The method according to p. 1, in which the latent image is imprinted into the medium by direct printing from a number of: flexographic printing, intaglio printing, screen printing

7. The method according to claim 1, wherein the thin transparent protective layer is a mechanically strong lacquer coating.

8. The method according to claim 1, wherein the security element is formed in such a way that it is part of one of the protected objects: banknotes, passport pages or other valuable document, plastic card. μ

9. The method according to claim 1, wherein the protective element is formed in such a way that it withstands a temperature of 180 ⁰ C.

10. An optical security element used to form a transparent window in a protected object, comprising a carrier that is transparent in the visible and ultraviolet regions of the spectrum, as well as latent images arranged on both sides of the carrier independently and / or in a predetermined coordinated position relative to each other with the possibility of forming a complex latent image during visualization, while the latent images on one side of the carrier are formed by a UV absorber with a red edge of the spectrum tensions in the range of 370-400 nm, and latent images on the other side of the carrier are formed by a UV absorber with a red absorption spectrum in the range of 270-360 nm; and a protective layer transparent in the ultraviolet region of the spectrum and formed on both sides of the carrier, the refractive index of the protective layer essentially coinciding with the refractive index of the carrier material and latent images, providing invisibility to the boundaries of the formation of latent images with the naked eye.

11. The method of verifying the authenticity of an object with a protective optical element according to claim 10, in which the object with a protective element is placed between a UV light source and a screen that fluoresces under the influence of UV light, while irradiating the protective element with UV light with a wavelength of 365 nm provides visualization of only areas with a latent image formed by a UV absorber with a red edge of the absorption spectrum in the range 370-400 nm; Irradiating the protective element with light with a wavelength of 254 nm provides visualization of areas with latent images formed by UV absorbers with a red border of absorption spectra in the ranges of 270-360 nm and with a red border of the absorption spectrum in the range of 370-400 nm, as a dark image on a luminous screen .

12. The method according to claim l l, in which the irradiation is carried out using a low-pressure mercury lamp.

13. The method according to p. L l, in which the screen is made of a material scattering light, on one side of which, facing the UV light source, a layer of fluorescent coating is applied. By proxy