RU2495753C1 - Cryptography and multiple positive-negative reading of information on colourless transparent polymer films - Google Patents

Abstract

FIELD: printing industry.

SUBSTANCE: proposed invention is designed for protection against counterfeit of packages and other items. Cryptography on the colourless transparent polymer film with the possibility of multiple positive-negative reading of information by means of application of information symbols onto the film with the help of local thermal impact and observation at different angle or in a clear space. Application of information is carried out through usage as a polymer film of unixially oriented rigid elastic polyolefin film, local thermal impact under pressure with subsequent deformation of elastic stretching along the axis of orientation.

EFFECT: proposed invention simplifies production of invisible images on a carrier with provision of high extent of counterfeit protection.

3 cl, 3 dwg, 4 tbl, 6 ex

Description

FIELD OF THE INVENTION

The invention relates to several fields of polymer physics, printing and protective technologies designed to protect against counterfeiting packaging and other products, including plastic structures with optical security features. Cryptography can be used for marking polymer labels or multilayer labels placed on packaging for advertising purposes and to increase the attractiveness of goods by involving the buyer in the process of verifying the authenticity of the goods or obtaining additional information about the terms or conditions of storage.

State of the art

Known technical solutions for the protection of plastic documents by manufacturing them in the form of multilayer thin-film structures in which the recording of identifying images and text is performed in different layers and on different surfaces of the polymer layers. At the same time, specific optical effects are achieved when viewing images and text at different viewing angles and different lighting angles. For example, in the application US 2005/0035590 A1, IPC B41M 5/24, publ. 02.17.2005, a method for cryptography and identification of a document made of a multilayer polymeric material, on which various images are applied on various surfaces, is proposed. Images are applied to the surface of individual layers prior to the formation of a multilayer structure by known printing methods. This method of cryptography is not convenient, and in many cases it is not applicable, because Often, individual labeling of each product or personalization after manufacture is required. According to the known method, the application of images on the surface of the layers cannot be carried out in the course of one printing cycle, and it is impossible to personalize the finished copy.

A known method of recording information on polymers by thermal exposure to a colored polymer, in which a colored textile material based on natural or synthetic polymers containing microcapsules with a shell of a specially selected polymer is used as a polymer. A “bad” non-polar solvent is placed inside the microcapsules, the substance is a color former and an acid color developer. Heating the material with microcapsules leads to the dissolution of the color former and developer in a solvent to obtain an intensely colored substance in microcapsules. The thermal effect on such a polymer makes it possible to record information on textile material (Andrievsky A. “Living” fabrics in Russia, Textile 1 (3), 2003). Information is not recorded secretly and is read visually from any angle in a positive or negative way without inverting tones.

There is also a method of recording information by thermal exposure to a colored polymer, according to which an elongated polymer product made of plasticized or unplasticized, amorphous or amorphous-crystalline polymer is used as a polymer, which is subjected to extraction in a adsorption-active medium of a number of alcohols at a temperature below the temperature the glass transition of the polymer, followed by treatment with an aqueous or alcohol solution of a non-thermochromic dye selected from the group including Rod amine 6G, methyl green and methylene blue, at a temperature below the glass transition temperature of the polymer, drying at a temperature below the glass transition temperature of the polymer and local heat treatment of the polymer at a temperature not lower than the glass transition temperature of the polymer. In this case, polymer films, fibers, tapes, tubes, rods can be used as an elongated polymer. This method is based on the phenomenon of crazing elongated polymers when they are drawn in a specially selected adsorption-active medium, which leads to the formation of an open microporous structure filled with dye in the polymer (RF patent 2385370, IPC D06P 5/20, publ. 03/27/2010, prototype )

The disadvantage of this method is the complexity and increased material consumption of the technology, the lack of indications of the potential for secret writing on colorless polymer films, as well as the use of the information recording method for protection from counterfeiting of printing products, film packaging and flexible packaging elements made of transparent thermoplastic polymeric materials.

Closest to the claimed technical solution is a method for covertly recording information on a transparent film and reading it when observing at various angles or in the light (method of secret writing and identification of markings) by applying information symbols and images to the film surface by local thermal exposure, for example, carbonization and / or laser beam engraving. At the same time, two rasterized images are formed in the surface layers of the film 1–40 μm thick, arranged in such a way that when observing the images at different angles or in the transparency, the observed total image smoothly changes from positive to negative or vice versa, while the first and second rasterized images made transparent and / or translucent, and / or reflective, and / or luminescent, and / or embossed. The invention allows for individual marking of the document to be protected in a single cycle by creating images that are changed during the observation process in a polymer film. The well-known method of cryptography and identification of markings is inextricably linked by a single concept, positive effect and technical implementation of a set of operations carried out with a material object (polymer film) to solve the technical problem of protecting the polymer product from counterfeiting by secret writing by local thermal exposure (RF patent 2386544, IPC B42D 15/10, G02B 27/60, published. 04/20/2010).

The disadvantage of this method is the complexity of the technology, the initial partial visibility of the characters printed on the film by carbonization or engraving, the lack of indications of the potential for cryptography on single-layer polymer films and the use of the method to protect against forgery of film packaging and flexible packaging elements.

The technical problem to which the invention is directed is the simplification of the method, obtaining images of information symbols invisible to the naked eye before film tensile deformation and the possibility of using the method to protect against copying and counterfeiting of film packaging and flexible containers made of thermoplastic polymeric materials.

SUMMARY OF THE INVENTION

The stated technical problem is solved in that secret writing on a colorless transparent polymer film and multiple positive-negative reading of information by applying information symbols to the film using local thermal exposure and observation at various angles or to the lumen according to the invention is carried out by using uniaxially as a polymer film oriented stiff-elastic polyolefin film, local heat exposure under pressure, followed by deformation elastic stretching along the axis of orientation.

As a polymer film of a uniaxially oriented rigid-elastic polyolefin film, a rigid-elastic isotactic polypropylene film is used, obtained by extrusion of a melt with accelerated die drawing and cooling on a temperature-controlled steel cylinder at a temperature of 80 ÷ 11 ° C, which is annealed at 130 ÷ 60 ° C with fixed sizes for 7 ÷ 42 hours. Local thermal action is carried out by a heated flat stamp or stamp, having the form of an information symbol, on one or two sides under a pressure of 200 ÷ 700 kPa at a temperature of 140 ÷ 480 ° C. Following the local thermal action, the deformation of the first elastic tension along the orientation axis is carried out immediately after the thermal action under pressure or with delayed reading of information. Following the local thermal influence, the deformation of the first elastic tension along the orientation axis can be carried out locally, i.e. in the place of heat exposure or completely, once or repeatedly without loss of the effect of positive-negative reading of information during subsequent storage and operation of the product.

The proposed method of cryptography and multiple positive-negative reading of information is inextricably linked by a single design, positive effect and technical implementation of a set of operations carried out with a material object (polymer film) to solve the technical problem of protecting the polymer product or packaging from forgery by local heat exposure and subsequent tensile strain of the film from which the protective elements of the package are made (label, brand, label). It is impossible to separate the cryptography method from the method of multiple positive-negative reading of information into independent technical solutions, because the last cryptography operation — the deformation of elastic stretching along the orientation axis at the site of heat exposure — coincides with the method of reading information. We believe that the application respects the principle of the unity of the technical solution.

The invention is illustrated by photographs of a transparent polymer film with identified (read) in a positive-negative embodiment, the recording of graphic information and examples of the method of cryptography.

Figure 1 is a photograph of a transparent polymer film on a dark background with recorded and detected graphic information in the form of a separate strip. 1 - identification of graphical information in a positive way; 2 - identification of graphical information in a negative form.

Figure 2 is a photograph of a transparent polymer film on a dark background with recorded and revealed graphic information in the form of a complex ornament. 3 - film with cryptography in unstretched condition; 4 - identification in a positive version of the graphic information when stretching the film; 5 - identification in a negative version of the graphical information when stretching the film.

Figure 3 is a diagram of a multilayer label of a polymer packaging protected from tampering, using hard-elastic films repeatedly revealing the security information recorded in cryptography. 6 - label in the initial state; 7 - label with a 15% deformed film; 7 - label with 30% deformed film; 8 - label with extremely stretched film.

Information confirming the feasibility of the invention

The proposal is illustrated by examples of the method, as well as the results of optical-mechanical testing of samples of a transparent polymer film. For heat treatment, we used the RDM TEST EQUIPMENT polymer modeling modeling stand.

Modes of heat treatment of films and the results of multiple positive-negative reading of information symbols printed in cryptography are presented in the following tables 1-4:

The quality of the obtained samples of the film of rigid-elastic polypropylene with cryptography was evaluated visually on the following seven-point scale:

1 point - the interval of low transparency (modified portion) is not visible before stretching, but when stretched it is implicitly visible and remains on the film at n.o. short time (less than 30 days);

2 points - the modified section is not visible before stretching, but when stretched it is visible implicitly, but remains for a long time (indefinite time *);

3 points - the modified section is not visible before stretching, but is clearly visible when stretching;

4 points - the modified section is not visible before stretching, but is visible well when stretched;

5 points - the modified area is not visible before stretching, but is very visible when stretched, the film at the modification site whitens more evenly when stretched;

6 points - holes are formed on the material at the edges of the modified section, or whitish spots are formed at the places of the film structure modification, the modified section is slightly noticeable before stretching due to defects: slight deformation of the material at the edges of the cut and slightly noticeable whitening of the material. When stretched, the dimensions of the holes increase; to break the material, in places where the holes appear, it is necessary to apply a force commensurate with the film strength before modification;

7 points - holes are formed on the material along the edges of the modified section, and whitish points are formed at the modification site, the modified section and white points are visible before stretching, and when the tensile is broken, the specimen breaks (breaking). Sometimes the destruction occurs before the stage of whitening of the material at the edges from the modified area. When stretching the film, the size of the holes increases rapidly. The gap of the material occurs in the places where the holes appear during deformation of about 10%. To break the film, a small force is required, several times less than the tensile strength of an unmodified film.

According to this classification, the optimal quality of thermal modification for the purpose of cryptography corresponds to 5 points.

Samples that were stretched immediately after a burn, during subsequent stretches, show a white color of the symbols applied by heat exposure more intensively than those that were stretched after 10 minutes or more. Moreover, if the specimen is stretched immediately after thermal cryptography operations (after 2-3 minutes, so that the film has time to cool down), then stretching will require significantly less effort than if it was stretched after 10-15 minutes or more.

Example 1. Carry out secret writing and multiple positive-negative reading of information by applying information symbols on a colorless transparent polypropylene film by local thermal exposure and observation at various angles and to the lumen. As a polymer film, a uniaxially oriented rigidly elastic polypropylene film is used, obtained by extrusion of a polypropylene melt with accelerated die drawing and cooling on a temperature-controlled steel cylinder at a temperature of 90 ° C, which is subjected to annealing at 150 ° C with fixed dimensions for 10 hours. Local thermal exposure was carried out by a heated flat stamp on both sides under a pressure of 450 kPa at a temperature of 160 ° C. After local heat exposure under pressure, the film samples were subjected to subsequent elastic deformation by 30% along the orientation axis of the polypropylene film. The quality of the obtained samples of the film of rigid-elastic polypropylene with cryptography corresponded to five points on a seven-point scale.

Example 2. Cryptography and multiple positive-negative reading of information is carried out according to example 1, but the temperature of the heated flat stamp is 140 ° C, the time is 2 s, the pressure is 414 kPa (60 psi). The quality of the obtained samples of the film of rigid-elastic polypropylene with cryptography corresponded to five points on a seven-point scale.

Example 3. Cryptography and multiple positive-negative reading of information is carried out according to example 1, but the temperature of the heated flat stamp is 160 ° C, the time is 1 s, the pressure is 414 kPa (60 psi). The quality of the obtained samples of the film of rigid-elastic polypropylene with cryptography corresponded to five points on a seven-point scale.

Example 4. Carry out secret writing and multiple positive-negative reading of information according to example 1, but the temperature of the heated flat stamp - 170 ° C, time - 1 s, pressure - 345 kPa (50 psi). The quality of the obtained samples of the film of rigid-elastic polypropylene with cryptography corresponded to five points on a seven-point scale.

Example 5. Cryptography and multiple positive-negative reading of information is carried out as in Example 1, but the temperature of the heated flat stamp is 150 ° C, the time is 1 s, the pressure is 483 kPa (70 psi). The quality of the obtained film samples of rigid-elastic polypropylene, with cryptography corresponded to five points on a seven-point scale. The film with information received by cryptography is stored unchanged for more than 4 months.

Example 6. Carry out secret writing and multiple positive-negative reading of information according to example 1, but the temperature of the hot tool is 140-170 ° C, the temperature difference between the heating elements is 50-150 ° C, the pressure is 200-500 kPa and the exposure time under pressure - 1-5 s. Received film samples with a zebra ornament (Figure 2), which manifests itself when the film is stretched. The film with information received by cryptography is stored unchanged for more than 2 months.

Claims (3)

1. Cryptography on a colorless transparent polymer film and multiple positive-negative reading of information by applying information symbols to the film using local thermal exposure and observation at different angles or to the lumen, characterized in that they are realized by using uniaxially oriented rigidly elastic as a polymer film polyolefin film, local heat exposure under pressure, followed by elastic tensile deformation along the orientation axis. 2. The cryptography according to claim 1, characterized in that a rigid-elastic film of isotactic polypropylene obtained by extrusion of a melt with a 4 ÷ 7-fold spinneret drawing and cooling on a thermostated steel cylinder at a temperature of 80 ÷ 110 ° C is used as a uniaxially oriented polymer-oriented rigid-elastic polyolefin film. , which is subjected to annealing at 130 ÷ 160 ° C with fixed sizes for 7 ÷ 12 hours. 3. Cryptography according to any one of claims 1 and 2, characterized in that the local thermal effect is carried out by a heated flat stamp or a stamp having the form of an information symbol, on one or two sides under a pressure of 200 ÷ 700 kPa at a temperature of 140 ÷ 180 ° C, and the deformation of the first elastic tension along the orientation axis following the local thermal effect occurs immediately after the thermal action under pressure.

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