RU2310241C2 - Method for manufacturing holographic labels - Google Patents

Abstract

FIELD: protection of valuable papers and documents from forgery.

SUBSTANCE: method for manufacturing holographic labels includes forming a hologram of marking sign image on the surface of working layer of label, registration of relief-phase marking sign image hologram by non-contact deformation of working layer of label, serial application of reflecting and gluing layers onto the working layer surface. The working layer of label is made in form of multi-layer structure, which includes a substrate and a photo-sensitive thermo-plastic registering layer. Hologram of marking sign image is formed using separate fragments, where aforementioned forming and also registration of relief-phase marking sign image hologram are partially combined in time.

EFFECT: increased level of protection of marking sign image hologram from possible forgery.

5 cl, 4 dwg

Description

This invention relates to the field of protection against counterfeiting of securities, documents, the printing industry, mainly for the manufacture of optical tags with holographic elements that are protective (against possible counterfeiting) or advertising in nature, as well as for the manufacture of labels for various purposes.

A known method of manufacturing holographic labels [1], which consists in the formation and registration of the primary hologram of the mark, the formation of a rainbow hologram and its copying on the label. Copying is carried out by registering a secondary hologram on a positive photoresistive material, etching, manufacturing a copy matrix from the etched secondary hologram, and applying a hologram of the image of the mark on the labels by contact deformation (stamping) using the copy matrix. In this case, as a substrate - the basis of the label using a metallized mylar ribbon.

The disadvantages of this method include the complex manufacturing technology caused by the multi-stage label manufacturing process and the multiple copying of holograms, as well as the low degree of protection due to the potential for copying the microrelief carrying information about the registered relief-phase hologram, since it is located on an external, open unauthorized access side of the label. The disadvantages of this method also include low speed due to the presence of operations of rewriting holograms and processes of photochemical processing.

In addition, the presence of stamping operations from the matrix makes it impossible to obtain single copies or even relatively small series of holographic labels due to the high cost of the technology used.

There is also known a method of manufacturing holographic labels [2], which consists in forming a hologram of the image of the mark, registering it on an intermediate recording medium, manufacturing a matrix - a relief copy of the registered hologram, fixing the relief phase hologram of the image of the mark by contact deformation of the working surface of the label onto which pre-applied reflective coating, and applying to the back of the label adhesive coating.

The disadvantages of the known method are similar to the disadvantages of the method [1] and are due to the same reasons.

Closest to the invention and chosen by the authors for the prototype is a method of manufacturing holographic labels [3], which consists in the formation of a hologram of the image of the mark on the surface of the working layer of the label, registration of the relief phase hologram of the image of the mark by contactless deformation of the working surface of the label, sequential application to the surface of the work a layer of reflective and adhesive layers, and the working layer of the label is formed in the form of a multilayer structure containing a substrate and otochuvstvitelny thermoplastic recording layer.

The disadvantages of the known method closest to the invention and selected by the authors for the prototype are:

- a relatively low degree of protection of the hologram from possible reading, caused by the ability to restore the geometric relief on the surface of the label and copy it when the working layer is chemically removed. An additional reduction in the degree of protection of the hologram from copying is due to the fact that in the prototype method, applying a reflective layer with a high reflection coefficient that provides high consumer properties of the fixed hologram chemically isolates the adhesive and working layers from each other, allowing the working layer to be removed using organic solvents without damaging microrelief, i.e. copy the hologram;

- the unsolved problem of identifying a separately considered holographic label at the level of a technical solution;

- low speed, due to the consistent nature of the formation of the hologram of the label on the surface of the working layer and the fixation of the relief-phase hologram.

The aim of the proposed method is to increase the degree of security of the hologram and increase speed.

The goals are achieved due to the fact that in the known method of manufacturing holographic labels, which consists in forming a hologram of the image of the mark on the surface of the working layer of the label, registering the relief phase hologram of the image of the mark by contactless deformation of the working layer of the label, sequentially applying a reflective layer to the surface of the working layer and adhesive layers, and the working layer of the label is formed in the form of a multilayer structure containing a substrate and photosensitivity An effective thermoplastic recording layer, a hologram of the image of the mark are formed from separate fragments, the formation and registration of the relief phase hologram of the image of the mark is partially combined in time.

This goal is also achieved by the fact that the fragments of the image of the hologram of the mark partially overlap spatially in the area of formation of the hologram.

This goal is also achieved by the fact that fragments of the image of the hologram of the mark are divided during formation into two groups: unchanged for the holographic labels being produced and individual (identification), different for each label.

This goal is also achieved by the fact that a masking layer is applied between the reflective and adhesive layers.

This goal is also achieved by the fact that the reflective layer is made partially transparent with a reflection coefficient less than 1.

Figure 1 shows a block diagram of a device that implements the proposed method (figure 1, a), where the following notation is introduced: coherent radiation source (laser) 1, shutter 2, hologram 3 forming circuit, marking 4, manufactured holographic label 5 , a time slider 6, a hologram recording device 7; a block diagram of a hologram recording device (FIG. 1, b), where the following designations are introduced: a direct current source 8, switches 9, a high voltage source 10 with an electrode 10a, a heat conductor 11; block diagram of the marking sign (FIG. 1, c), where the designations are introduced: the space-time light modulator 12, the original marking sign (transparency) 13, the beam splitter 14, the encoding device 15.

Figure 2 shows a view of the hologram of the mark and the following notation is introduced: an invariable fragment of the hologram of the mark 16, a fragment individual for each hologram of the mark 17, the overlap area of the fragments 18.

Figure 3 shows the timing diagram of the processes of formation and fixation of the hologram of the mark for the prototype method (figure 3, a) and the proposed method (figure 3, b). Letters A, B indicate cyclograms of the processes of formation and fixation of the hologram of the mark. The letter B marks the sequence diagram of the input-output process of sequentially produced holographic marks from the zone of formation and fixation of the hologram.

Figure 4 shows a section of a holographic label in the manufacturing process after applying the working layer (figure 4, a), after fixing the relief phase hologram (figure 4, b), after applying the adhesive layer (figure 4, c - without applying 4, d, when applying the masking layer) and the following designations are introduced: substrate 19, working layer 20, relief phase hologram 21, reflection layer 22, adhesive layer 23, masking layer 24.

The essence of the proposed method is as follows.

A mark 4 is formed, the hologram of the image of which must be fixed on the label. The mark itself is physically either a banner, or a three-dimensional model, or a combination of flat and three-dimensional components. A distinctive feature of the proposed method is that the hologram of the image of the mark is formed from individual fragments, i.e. the mark, in turn, is a collection of individual fragments. Consider the possible image of the mark (figure 2).

For the first option, the fragment 16, which is unchanged for the entire set of generated holograms of the image of the marking sign, for example, a trademark of a company; a fragment 16a that is unchanged for a certain group of generated holograms of the image of the marking sign, for example, the code of the protected document. Figure 2, a shows a view of two such markings having an unchanged fragment of a hologram of a label and different codes of documents to be protected (unchanged fragments A1 and B1).

For the second option, the fragment 16, which is unchanged for the whole set of generated holograms of the image of the marking sign, for example, a trademark of a company; Fragment 16a, which is unchanged for a certain group of generated holograms of the image of the mark, for example, the code of the protected document, fragment 17 changing from hologram to hologram, for example, the hologram serial number (21 and 22). Figure 2, b shows a view of two such sequentially produced holograms of the image of the marking sign having an unchanged fragment of the hologram of label 16 (for example, a trademark), the code of the protected document (A1) and the original fragment 17 for each individually generated and registered hologram hologram number (21 and 22).

These fragments of holograms can be either spatially separated, disjoint, as shown in Fig. 2, a and 2, b, or partially spatially coincide, forming a complex interference pattern in the intersection, as shown in Fig. 2, c. This figure shows two options for the intersection of various fragments of the generated hologram. Moreover, since in the region of the spatial intersection of fragments of the generated hologram, one of the fragments is individual for each individual hologram, the region of spatial intersection will also be an interference pattern that varies from hologram to hologram. Of particular interest is the option presented in the second picture of figure 2, c. In this case, an individual fragment for each hologram - number (T22) defines the boundary of fragment 17 (its shape). The inner region of this fragment is common for fragments of the hologram 16 and 17. After registration of the hologram of the image of the mark, when it is visualized, in contrast to the known cases of numbering of holograms of the image of the mark, the internal filling of the number (individual, changing for each hologram!) Will represent a rainbow interference pattern, generally changing from label to label, which further complicates the process of copying a hologram into firs fakes.

When marking sign 4 is illuminated with coherent radiation from laser 1, a coherent image is obtained, which is converted by means of an optical system to form a hologram of a given type, for example, a Fourier hologram, a rainbow hologram, an image hologram. The formation of a hologram of the image of the mark is carried out on the surface of the working layer made of a thermoplastic material with the property of photosensitivity. Beams of coherent radiation forming a hologram of the marking image cause local changes in the physicochemical properties of the photothermoplastic material at each point of the working layer, mainly a change in the surface electrostatic charge. Before the formation of the hologram, a uniform electrostatic charge is applied to the surface of the working layer, which, when exposed to radiation (spatially modulated accordingly to the generated hologram of the image of the mark), is converted due to radiation-induced photoconductivity into a potential relief — the distribution of local surface charge values over the surface of the working layer proportional to the spatial distribution of radiation intensity forming a hologram and the surface of the working layer.

By heating the working layer to a temperature higher than the glass transition temperature of its material, the formed potential relief is transformed into a geometric microrelief, the depth of which is proportional to local variations in the surface charge and, therefore, the local intensity of coherent radiation, which forms a hologram of the mark. The process of converting a potential relief into a geometric one is due to the following physical processes. When the working layer is heated to a temperature higher than the glass transition temperature (average melting temperature of polymeric materials), the working layer becomes fluid, as a result of which local inhomogeneities of the surface charge lead to the appearance of surface tension forces that repel sections of the working layer that have large surface charges.

The termination of the heat load leads to the solidification of the working layer and allows you to fix the geometric microrelief, thereby registering the relief phase hologram of the image of the mark. In this case, the deformation of the working layer of the label is carried out non-contact, due to the formation of a potential relief and its transformation into a geometric microrelief due to the thermal effect on the working layer.

In order to improve the quality of the registered hologram, the operations of forming and registering the hologram of the image of the mark are partially combined in time.

In the prototype method, the operations of forming a hologram of the image of the marking sign (forming a potential relief on the surface of the working layer) and registering the relief-phase hologram (converting the potential relief to geometric and fixing the geometric microrelief) are carried out sequentially (see time diagrams A and B in figure 3 , but). This leads to a decrease in the diffraction efficiency of the recorded hologram due to the partial spreading of the potential relief (caused by the finite conductivity of the working layer) and, therefore, to a decrease in the quality of the hologram. In the proposed method, these processes partially coincide in time (see time diagrams A and B in Fig. 3, b). In this case, in addition to reducing the time of formation of the hologram of the sign and its registration, which provides increased performance of the proposed method, the quality of the generated hologram increases. This can be explained as follows. The process of forming a hologram on the surface of the working layer leads to the appearance of a surface gradient of the electrostatic field, i.e. to the appearance of a potential relief. When the material of the working layer is softened during thermal exposure, the thermoplastic material acquires fluidity, i.e. acquires some properties of a liquid. If during the heat exposure continue the process of exposure of the working layer by radiation, i.e. to continue the process of forming the hologram of the label, then due to the photosensitivity of the material of the working layer, the process of forming the potential relief will continue, which will lead to an increase in the gradients of the surface charge along the surface of the working layer, and consequently, to an increase in the depth of the geometric relief. This leads to an increase in the diffraction efficiency of the recorded relief-phase hologram, thereby increasing its quality.

The formation of a hologram and its registration on the surface of the working layer of the manufactured label, similarly to the prototype method, is carried out directly on the surface of each individual label, which allows you to enter fragments individual for each label into the hologram of the image of the marking sign (see figure 2).

After registering the hologram, a reflective layer 22 made of metal (aluminum, silver, molybdenum, etc.) is applied, for example, to the surface of the working layer. A reflective coating increases the diffraction efficiency of a fixed hologram, increasing its consumer properties. At the same time, the implementation of the reflective layer is partially transparent, with a reflection coefficient less than 1, increases the protective properties of the hologram of the image of the mark, reducing the possibility of high-quality copying and complicating the fake process.

When applying a reflective coating to dielectric surfaces (microrelief of the working layer 20), the reflection coefficient depends on both the material properties of the reflective coating and its thickness. Therefore, when applying a thin reflective coating having a residual transparency, i.e. having a reflection coefficient less than 1, this layer due to the presence of micropores is not insulating (in the sense of chemical inertness), providing chemical contact and chemical interaction of the adjacent layers of the holographic label (working layer 20, adhesive coating 23, masking layer 24). When this condition is fulfilled, it is difficult to counterfeit a holographic label by unauthorized copying, since in order to copy a registered phase-hologram, it is necessary to remove the working layer 20 in order to gain access to the actual hologram - a geometric microrelief. Due to the thinness of the layers (fractions and units of microns), this can only be done chemically by dissolving layer 20. If the reflective layer 22 is thin, then when the working layer is dissolved, the solvent particles penetrate through layer 22 and partially dissolve the underlying layers (adhesive layer 23 and masking layer 24), which leads to a distortion of the geometric microrelief (due to "blurring" of the fine high-frequency structure of the hologram) and, consequently, to the inability to copy the hologram with high quality.

An adhesive layer 23 is applied over the reflective coating onto the generated hologram of the image of the mark. This layer is applied over the reflective. It provides fixation of the formed holographic label on the surface of the protected document. The adhesive layer is made of a material, mainly organic, with good adhesive properties to the label layers in contact with it and to the surface of the document to be protected (paper, plastic).

To increase the degree of protection of the holographic label from counterfeiting between the reflective and adhesive layers, an additional masking layer 24 is applied, made of a photosensitive thermoplastic material similar in physical and chemical parameters to the material of the working layer 22. This layer is made of material that is close or identical in physical and chemical properties the material of the working layer. After applying this layer, the recorded phase-hologram is inside two layers with identical physicochemical parameters, at the interface of which a reflective coating is applied. The residual porosity of the reflective layer, provided by its small thickness with a reflection coefficient less than 1, further increases the adhesion of the working (20) and masking (24) layers. Moreover, this structure does not allow the removal of contact copies of registered holograms when destroyed in any way, for example by chemical dissolution of one of the layers due to the partial dissolution of the underlying layer.

For a more complete description of the operation of the claimed method, we give an example of its implementation in the device.

The marking sign 4 is highlighted by laser radiation 1 through the shutter 2, and by means of a hologram generating circuit 3, a hologram of the marking image is formed on the surface of the working layer 20 of the holographic label 5. Before forming a hologram, an electrostatic charge is applied to the surface of the working layer of the label 5. It is applied by placing the label in the discharge gap formed by the grounded heat conductor 11 and the electrode 10a of the high voltage voltage source 10.

The thermal manifestation of the generated hologram is carried out by connecting a direct current source 8 to the heat conduit 11 through the key stage 9. The heat conduit is in thermal contact with the label (its substrate 19) and is, for example, a conductive coating on a dielectric base, pressed against the back of the label. During thermal development, the material of the working layer softens and the potential relief is transformed into a geometric microrelief (thereby registering the relief phase hologram of the image of the mark). Removing the heat load by turning off the key stage 9 leads to the solidification of the working layer and to fixation of the registered hologram. The synchronization of the processes of electrostatic charge deposition, exposure of the working layer by coherent radiation, development and fixation of the hologram is carried out by means of a time slider 6, equipped with output keys and acting as a synchronizer. The timing diagram of the implementation of these processes corresponds to that shown in figure 3, b, i.e. the processes of formation and registration of the relief phase hologram partially coincide in time.

To increase the diffraction efficiency of the registered hologram, a reflective layer 22 is applied, for example, by evaporation in vacuum on the working layer 20 of the label of a thin metal layer. As the coating material, silver, aluminum, molybdenum and other metals can be used. Varying the residence time of the label in the active zone of the spraying installation, the thickness of the applied reflective layer is selected, which provides a given reflection coefficient of less than 1 and corresponding to the presence of partial transparency of the layer. After applying the reflective coating, an adhesive layer 23 is applied to it, made of a material having strong adhesive properties to the material of the object on which the label is applied. If the labels are intended to be applied on paper substrates, for example documents, then the adhesive coating can be made of a material having thermal adhesive properties. In the case of applying labels to massive objects, the adhesive coating can be made of a material having the properties of cold glue, for example, adhesive tape. In this case, the adhesive coating is performed in two layers, including the adhesive coating itself and a protective layer, for example, of a polyethylene film.

For the method according to claim 4, before applying the adhesive coating 23, a masking layer 24 is applied to the reflective coating 22, made of a material similar in physical and chemical properties to the material of the working layer 20.

Sequential application of the working and masking layers of the adhesive coating on the substrate is carried out using standard sprinklers.

Application of the manufactured label to the carrier (document to be protected, packaging, etc.) is subsequently carried out by the working side of the label to the carrier either by heating the hot-melt adhesive, or by removing the protective layer and mechanical contact of the cold glue with the surface to be protected.

The main advantage of the proposed method compared to the prototype is to increase the security of the hologram of the image of the marking from possible falsification. This is explained by an increase in the quality of the registered hologram due to the partial combination of the formation and registration of the relief phase hologram in time, the implementation of the reflective coating partially transparent and the application of a mask layer (the last two operations make it impossible to mechanically copy the microrelief of the relief phase hologram by chemically removing the outer layers of the label ) An additional positive effect is the increase in speed associated with the partial combination in time of the processes of formation and registration of the relief-phase hologram.

List of used scientific and technical literature.

1. Journal of America, No. 340, March 1985, pp. 46-48.

2. Optical holography. / Ed. G. Culfield, vol. 2, M .: Mir, 1982, p. 412-413.

3. Russian patent No. 2035762, MKI 6 G03H 1/00, B44F 1/12, B42D 15/10, B44F 1/14, G09F 19/12/19 | 20 - the prototype.

Claims (5)

1. A method of manufacturing holographic labels, which consists in forming a hologram of the image of the mark on the surface of the working layer of the label, registering a relief phase hologram of the image of the mark by contactless deformation of the working layer of the label, sequentially applying reflective and adhesive layers to the surface of the working layer, the working layer of the label form in the form of a multilayer structure containing a substrate and a photosensitive thermoplastic recording layer, distinguish In that the hologram of the image of the mark is formed from separate fragments, the formation and registration of the relief phase hologram of the image of the mark is partially combined in time. 2. The method according to claim 1, characterized in that the image fragments of the hologram of the mark partially overlap spatially in the hologram formation region. 3. The method according to claim 1 or 2, characterized in that the image fragments of the hologram of the marking sign are divided into two groups during formation: unchanged, for manufactured holographic labels and individual (identification), different for each label. 4. The method according to claim 1, characterized in that a masking layer is applied between the reflective and adhesive layers. 5. The method according to claim 1, characterized in that the reflective layer is made partially transparent with a reflection coefficient less than 1.

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