Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
  • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
  • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
  • B42D25/40—Manufacture
  • B42D25/405—Marking
  • B42D25/43—Marking by removal of material
  • B42D25/445—Marking by removal of material using chemical means, e.g. etching
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
  • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
  • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
  • B42D25/30—Identification or security features, e.g. for preventing forgery
  • B42D25/351—Translucent or partly translucent parts, e.g. windows
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
  • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
  • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
  • B42D25/30—Identification or security features, e.g. for preventing forgery
  • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
  • B42D25/364—Liquid crystals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
  • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
  • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
  • B42D25/30—Identification or security features, e.g. for preventing forgery
  • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
  • B42D25/373—Metallic materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
  • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
  • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
  • B42D25/40—Manufacture
  • B42D25/45—Associating two or more layers
  • B42D25/465—Associating two or more layers using chemicals or adhesives
  • B42D25/47—Associating two or more layers using chemicals or adhesives using adhesives

Definitions

• the present invention relates to a security element for documents, particularly banknotes, which is useful and practical in the field of the production of security papers and of anti-counterfeiting instruments in general.
• the invention also relates to a method for providing such security element.
• Another optical effect that is currently used in the security sector is color shift, according to which it is possible to obtain a color variation of the security element according to the viewing angle.
• Color shift security elements are currently commercially available which are provided by means of three different principles in order to generate the color shift.
• a first known type of security element is constituted by color shift security elements provided by using OVI inks (Optically Variable Inks).
• This element is produced, for example, by using a polyester base medium covered with aluminum.
• a colored (generally black but certainly always very dark) protective ink is printed on this aluminum in negative and/or in positive, according to the technical specifications.
• the first purpose of this ink is to be used as resist and therefore to protect the aluminum during the demetallization step, leaving it exposed where one wishes it to be removed; a second purpose is to improve the characteristics of the OVI ink despite not being transparent.
• the printing technique used to print this resist ink is generally rotogravure printing, but the flexographic or screen printing technique can also be used.
• the OVI ink is printed over the black ink and, due to the large particle size of the birefringent pigment, it must be printed with a certain quantity in order to cover the black ink adequately; in this case, however, the metallized regions are partially covered by the OVI ink and are not perfectly transparent.
• a second known type of security element is constituted by color shift security elements provided by using a liquid crystal ink.
• one of the processes used for this security element is very similar to the preceding one, except for the final ink, which is based on liquid crystals and not on OVI pigments.
• the difference consists in the fact that the liquid crystal ink is transparent and therefore allows better viewing of graphic marks when the security element is observed in transmitted light.
• a second process related to this second known type of security element is the one described in patent no. US010286717B2, based on the use of a transparent resist which protects the aluminum in the areas in which it must not be removed and a dark photosensitive ink which becomes selectively soluble when irradiated by an appropriate source.
• the layer based on liquid crystals is added to the security element thus obtained so as to give it the color shift functionality, leading to a large and expensive total of steps in order to achieve the intended purpose.
• a third known type of security element is constituted by color shift security elements provided by using a technique known in the field as thin film.
• This security element is produced by depositing on polyester, by means of a vacuum vaporization technique, nanometer layers of inorganic films with different refractive indexes. The difference in refraction index and the nanometer thickness of the layers allow to obtain the color shift optical effect by light interference.
• a layer of aluminum is then vaporized over the last layer of thin film.
• a resist is then printed over said aluminum layer in negative and/or in positive, generally with a rotogravure technique, and is meant to protect the aluminum selectively.
• This material is then demetallized by using acidic solutions, for example phosphoric acid, basic ones, for example caustic soda (obviously in the concentrations useful for this purpose).
• the background art has security elements characterized by a visual appearance which is similar, based on the phenomenon of birefringence, but limited from the point of view of the number of optical effects "in register" that are present simultaneously, due to the characteristics of the various production processes.
• the aim of the present invention is to provide a method for providing a security element for documents and a security element which are capable of solving the problems and overcoming the limitations of the background art described above.
• an object of the present invention is to devise a method for providing a security element for documents that is easier to provide and economically competitive if compared with the background art.
• Another object of the invention is to devise a method for providing a security element for documents that offers a high level of security.
• a further object of the invention is to devise a method for providing a security element for documents that is hard to counterfeit and allows the public to verify easily the authenticity of the document in which it is inserted.
• Not least object of the invention is to devise a method for providing a security element that is highly reliable, relatively simple to provide and at competitive costs.
• Figure 1 is a sectional view of a layered element formed in a first step of the method according to the invention
• Figure 2 is a sectional view of a perforated layered element which is formed in a second step of the method according to the invention
• Figure 3 is a sectional view of a finished security element, provided by means of a method according to the invention.
• Figure 4 is a top plan view of the security element of Figure 3;
• Figures 5 A, 5B and 5C are views of the appearance of the security element of Figure 3 when viewed from different viewpoints.
• the method for providing a security element for documents, particularly banknotes, designated generally by the reference numeral 1, in its general outline comprises the following steps.
• the method supplies a base medium 21 which is (at least partially) transparent, preferably made of polyester, preferably having a thickness comprised between 8 and 50 microns (and even more preferably between 12 and 15 microns).
• a base medium 21 is for example a rectangular lamina.
• a metallic layer 31 preferably made of aluminum, is then deposited on the base medium 21, preferably but not necessarily by means of a vacuum deposition technique.
• the metallic layer 31 has an opacity from 1.42 to 2 Optical Density (preferably 1.8).
• the metallic layer 31 is deposited so as to cover completely at least one background area 23, which corresponds to all of a face of the base medium 21 or to a portion thereof.
• the metallic layer is therefore arranged on a respective base level 11.
• the method then provides for printing (i.e., depositing by means of any known printing technique) on the metallic layer 31 a series of ink layers 32, 33, 34, 35, 36 arranged on superimposed levels 12, 13, 14, 15, 16, each on a respective level 12, 13, 14, 15, 16, so as to obtain a layered element 1".
• These ink layers 32, 33, 34, 35, 36 each comprise an ink which belongs to one of the following two categories:
• - inks which are soluble (with at least one predetermined acidic and/or basic solution which will be used hereinafter), i.e., which form layers which are soluble to acidic and/or basic solutions, i.e., have the characteristic of being dissolved or in any case removed when in contact with said one or more acidic and/or basic solutions which will be used in a subsequent step of the method and which are unable to remove the insoluble inks, said soluble inks being optionally characterized by different removal speeds.
• such ink layers 32, 33, 34, 35, 36 comprise at least one first layer of a first ink 32 which is insoluble with at least one predetermined acidic or basic solution and is arranged on a lower level 12 and the projection in plan view of which on the background area 23 covers only partially said background area 23, so that said lower level 12 also comprises areas 42 which are free from the insoluble ink.
• a portion preferably having a polygonal shape
• This portion has such a shape and dimensions as to contain at least one graphic element which is in practice colored with said first insoluble ink.
• Such first insoluble ink can be transparent or colored (for example yellow) and/or UV fluorescent in the visible region and/or additized with other effects that belong to security levels higher than the first one.
• the coloring is provided in a known manner by loading the ink with appropriate pigments.
• This first layer of a first insoluble ink 32 has the function of protecting the underlying metal from demetallization by the predetermined acidic or basic solution that will be used later in the method, as will become better apparent hereinafter.
• At least one layer of an ink 33, 35 which is soluble with said at least one predetermined solution is then printed over both the metallic layer 31 and the first layer of a first insoluble ink 32.
• Such first soluble ink preferably has a dark and hiding color (for example black). The color can in any case be chosen depending on the optical effect that one wishes to obtain.
• the at least one layer of soluble ink 33, 35 is arranged on a respective intermediate level 13, 15 which lies above said first level 12 and is printed on the full surface, i.e., extended so that its projection in plan view on the background area 23 covers completely said background area 23.
• the at least one layer of a soluble ink 33, 35 comprises a first layer of soluble ink 33 which has a first color (preferably dark) and also a second layer of a second soluble ink 35 of a second color (preferably not hiding or with low hiding, for example green) which is different from said first color.
• this second layer of soluble ink 35 also is printed on the full surface, i.e., extended so that his projection in plan view on the background area 23 covers completely said background area 23.
• identifying elements 34 are printed on respective graphically identifying areas with a third soluble ink which has a third color which is different from the first and second colors (for example gray or silver).
• identifying elements 34 formed by the third soluble ink are therefore positioned on a respective internal level 14, which also comprises areas 44 which are free from the third soluble ink which forms the identifying elements 34.
• the identifying elements 34 can be more than one, as in the example shown.
• the second soluble ink layer 35 has no effect at the free areas 44 of the internal level 14, i.e., where it is superimposed directly on the first dark (black) soluble ink, maintaining instead its original color when it is superimposed on the (gray or silver) ink that forms the underlying identifying elements 34.
• a layer of a second ink 36 which is insoluble with said at least one predetermined solution is then printed over the layers 32, 33, 34, 35 that have just been described, and is arranged on an upper level 16 which lies above the intermediate level 13, 14, 15.
• this layer of a second insoluble ink 36 is printed directly over the second layer of soluble ink 35.
• the second insoluble ink used to print the layer of second insoluble ink 36 is preferably different from the first insoluble ink used for the first layer 32 and is preferably transparent, even more preferably is an ink of the resist type.
• This layer of a second insoluble ink 36 is formed by portions which are not mutually continuous and therefore its projection in plan view on the background area 23 covers said background area 23 only partially.
• the layer of a second insoluble ink 36 is printed so that said upper level 16 also comprises areas 46 which are free from the insoluble ink, and so that at least one of said free areas 46 of the upper level 16 is aligned at least along a respective first transverse axis XI, X2, X3 with one of the free areas 42 of the lower level 12.
• At least one of the free areas 46 of the upper level 16 is aligned at least along a respective second transverse axis Y1,Y2 with the first layer of an insoluble ink 32.
• the first insoluble ink 32 has a fourth color (for example yellow) which is different both from the first color (of the first layer of soluble ink 33) and the second color (of the second layer of soluble ink 35), and the second insoluble ink 36 is preferably transparent.
• a fourth color for example yellow
• the immersion of the layered element 1" in the solution causes a chemical action of this solution capable of removing the soluble inks and the metal to create, in the layered element 1", at least one optically clear hole 4a, 4b and 4c at the at least one first transverse axis XI, X2, X3 and at least one dead hole 5a, 5b at the at least one second transverse axis Yl, Y2, thus obtaining a perforated layered element 1' as shown in Figure 2.
• each optically clear hole 4a, 4b, 4c extends from the upper layer 16 to the background area 23, while each dead hole 5a, 5b is limited in a lower region by the first layer of an insoluble ink 32, which in practice acts as a shield, protecting the underlying metallic layer 31.
• the layer of a second insoluble ink 36 arranged on the upper level 16 protects all the underlying layers from the action of the acidic and/or basic solution.
• optically clear holes 4a, 4b, 4c are optically clear in the sense that they can be crossed by visible light since they are closed only by the base medium 21, which is at least partially (and preferably completely) transparent to visible light.
• the dead holes 5a, 5b are dead in that they cannot be crossed by visible light, since they are closed in a lower region also by the metallic layer 31 and by the first layer of colored insoluble ink 32.
• the layered element 1" is immersed in a tank which contains a first predetermined solution, which is preferably basic, capable of dissolving at least the soluble inks (as already explained, the insoluble inks are chosen so as to be insoluble with said first solution).
• a first predetermined solution which is preferably basic, capable of dissolving at least the soluble inks (as already explained, the insoluble inks are chosen so as to be insoluble with said first solution).
• this first solution is a solution of sodium carbonate (preferably 1%) in water at a temperature equal to or higher than 40°C (preferably 40°C).
• the layered element 1" is then immersed also in a second solution, which is preferably acid and is capable of dissolving at least the metal of the metallic layer 31 (the insoluble inks being insoluble also with this second solution).
• a second solution which is preferably acid and is capable of dissolving at least the metal of the metallic layer 31 (the insoluble inks being insoluble also with this second solution).
• this second solution is a solution of phosphoric acid (preferably 50%) in water at a temperature equal to or higher than 52°C (preferably 52°C), which is capable of dissolving at least the metallic layer 31 when it is made of aluminum.
• this process of immersion in one or more solutions allows to "excavate” simultaneously layers printed and/or deposited with different techniques.
• the free areas 46 of the upper level 16, the free areas 42 of the lower level 12 and the first layer of an insoluble ink 32 are arranged and shaped so that each of the optically clear holes 4a, 4b, 4c and of the dead holes 5a, 5b forms, in plan view, a recognizable graphic symbol (i.e., graphic marks, such as for example symbols, designs, alphanumeric characters, geometric shapes, or the like).
• the through holes 4a, 4b, 4c form alphanumeric characters (respectively the letters "E” and "A” and the numeral "5").
• At least one upper covering layer 38, 22, is fixed over the perforated layered element 1', on a face which is opposite with respect to the base medium 21, so as to close upward all the holes 4a, 4b, 4c, 5a, 5b.
• the at least one upper covering layer 38, 22 is at least partially transparent to visible light, so that the optically clear holes 4a, 4b, 4c continue to be optically clear.
• Such upper covering element comprises at least one (at least partially and preferably completely) transparent external layer 22 which is preferably made of polyester like the base medium 21.
• the at least one upper covering layer comprises, in addition to the external layer 22, also a birefringent internal layer based on liquid crystals 38 (which is internal in that it is arranged inside internally toward the underlying layers 36, 35, 34, 33).
• the birefringent internal layer of liquid crystals 38 is deposited beforehand on the external layer 22.
• the at least one upper layer covering layer 38, 22 is fixed to the perforated layered element T by means of an interposed transparent adhesive layer 37.
• both the adhesive layer 37 and the layer of second insoluble ink 36 are transparent, the colors that emerge are derived from the interaction between the optical color absorption properties of the underlying layers 32, 33, 34, 35 (for example respectively yellow, black, silver, green) and of the birefringent layer based on liquid crystals 38.
• the security element 1 thus provided can be further enhanced:
• second-level security effects such as UV materials which are fluorescent in the visible spectrum
• second-level security effects such as UV materials which are fluorescent in the visible spectrum
• the sum of all the layers provides the different colors depending on the viewing angle 01, 02.
• Figures 5 A, 5B, 5C show the security element viewed from different viewpoints.
• Figure 5 A shows the appearance of the security element 1 viewed in transmitted light: one can see only the optically clear holes 4a, 4b, 4c, i.e., the areas that are optically transparent in the visible spectrum (which in the example form the letters "E"-"A" of the word “EPTA” and the numeral "5" inside the illustration).
• Figure 5B shows the appearance of the security element 1 viewed in reflected light, according to an inclination 01: the background of a single color, designated in the figure by the letter V, and the dead holes 5a, 5b of a second color, which corresponds to the color of the first layer of insoluble ink 32, can be seen.
• dead holes 5a, 5b form the letters "P"-"T" of the word "EPTA”.
• the birefringent layer based on liquid crystals 38 has a color similar to V, creating a monotonic effect (for example green).
• Figure 5C shows the appearance of the security element 1 viewed in reflected light, according to an inclination 02: two colors are observed: V and R between the background and the graphic elements, with the addition of the color of the dead holes 5a, 5b (already observed by tilting the security element according to 01).
• the birefringent layer based on liquid crystals 38 has a different color with respect to V, creating a two-color effect (for example red and green) on the background.
• One possible alternative embodiment has, with respect to the embodiment shown, the following differences: instead of the two layers of soluble inks 33, 35 printed on the full surface there is a single layer of soluble ink printed on the full surface and instead of the layer of transparent insoluble ink 36, again arranged at an upper level 16, there is a layer of insoluble ink that is at least partially transparent and preferably colored (for example green).
• said embodiment also comprises the identifying elements 34 formed by a third soluble think, which are arranged on a respective internal level 14 which is located between the first level 12 and the upper level 16 (above or below the layer of soluble ink printed on the full surface).
• the security element 1 for documents according to the present invention obtainable by means of the described method, comprises:
• a series of layers of ink 32, 33, 34, 35, 36 arranged on superimposed levels 12, 13, 14, 15, 16, each on a respective level 12, 13, 14, 15, 16, said layers of ink 32, 33, 34, 35, 36 comprising: at least one first layer of a first ink 32 which is insoluble with at least one predetermined acidic or basic solution, arranged on a lower level 12 and the projection in plan view of which on said background area 23 covers the background area 23 only partially, so that the lower level 12 also comprises areas 42 which are free from the insoluble ink, at least one layer of an ink 33, 35 which is soluble with the at least one predetermined solution, arranged on a respective intermediate level 13, 15 which lies above the first level 12, a layer of a second ink 36 which is insoluble with said at least one predetermined solution, arranged on an upper level 16 which lies above the intermediate level 13, 15 and the projection in plan view of which on the background area 23 covers only partially the background area 23, so that the upper level 16 also comprises areas 46 which are free from the in
• optically clear hole 4a, 4b, 4c at least one optically clear hole 4a, 4b, 4c and at least one dead hole 5a, 5b, the optically clear hole 4a, 4b, 4c being extended from the upper level 16 to said background area 23, said dead hole 5a, 5b being limited in a lower region by said one first layer of an insoluble ink 32;
• the upper covering element 38, 22 comprising an external layer 22 which is at least partially transparent.
• the security element can be inserted, in a known manner, in a valued document, such as a banknote, to allow to verify its authenticity.
• Another advantage of the method according to the invention resides in that it offers a high level of security.
• a further advantage of the method according to the invention resides in that it is hard to counterfeit and allows easy verification by the public of the authenticity of the document in which it is inserted.
• the invention furthermore provides a valid alternative to the background art.
• the materials used, as well as the contingent shapes and dimensions may be any according to the requirements and the state of the art.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Crystallography & Structural Chemistry (AREA)
• Credit Cards Or The Like (AREA)

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• 2021
  • 2021-12-21 EP EP21843729.1A patent/EP4271572A1/de active Pending
  • 2021-12-21 WO PCT/EP2021/087154 patent/WO2022144258A1/en unknown

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