OPTICAL MARKING DEVICE AND DOCUMENT OR LABEL COMPRISING THE SAME

Abstract

optical marking device. The invention relates to an optical marking device comprising at least a first layer (2) and a second layer (3) arranged at least partially opposite each other, at least one of said first and second layers comprising an optically variable element (4, 5) capable of changing color between a first color and a second color, said first and second layers in contrast to a color of the other layer such that when the optically variable element (4, 5) presents the first color, the first layer (2) is visible and when the optically variable element (4, 5) presents the second color, the second layer (3) is visible or when the optically variable element (4, 5) presents the first color, the second layer (3) is visible and when the optically variable element (4, 5) presents said second color, the first layer (2) is visible.

Description

1 / 53 OPTICAL MARKING DEVICE AND DOCUMENT OR LABEL COMPRISING THE SAME

[0001] The present invention relates to the field of product security and authentication, particularly of documents.

[0002] Refers more specifically to the security and authentication of identity, fiduciary or administrative documents or brand labels.

[0003] Counterfeiting and the production of counterfeit goods are now becoming increasingly significant in many high value-added sectors such as luxury goods, automotive and aeronautical components, or packaging, notably for medicinal products such as pill packaging.

[0004] With the development of identity theft and, especially, the establishment of points-based driver's licenses in certain countries, identity and administrative documents are increasingly targeted for forgery. The security and authenticity of these types of products and documents are therefore crucial and involve both national and international security issues.

[0005] Thus, it is necessary to continually provide new means to effectively combat counterfeiting, especially the alteration of an original document, or forgery (production of counterfeit goods).

[0006] Here in the following description, the term “document” refers to a set consisting of a substrate and information. The substrate can be of various types, can take various forms, and can comprise a polymer or a mixture of polymers. Said substrate, for example, can Petition 870260014400, dated 02 / 13 / 2026, page 21 / 24 2 / 53 consist entirely or partially of a polymeric material.

[0007] Examples of documents include identity documents such as passports, identity cards, driver's licenses or health cards, but also fiduciary documents such as banknotes and checks or administrative documents, for example, such as registration certificates.

[0008] Therefore, documents can be in the form of paper, a book, or a card, and the information can be either printed on it and / or marked on the surface, when it is paper or card, or on the pages in the case of a book.

[0009] In view of the important value associated with the information contained therein, the documents must be made secure.

[00010] Currently, documents are made secure by security elements, which can be classified according to three security levels as a function of the means employed for detection. Thus, level 1 security elements are elements that can be detected by at least one of the five senses or by means of a contrasting background. This level mainly includes guilloches, devices with optical variability such as iridescent printing, holograms, optically variable inks, markers, changeable laser images or multiple laser images. Petition 870200161541, dated 12 / 28 / 2020, p. 9 / 63 3 / 53

[00011] Level 2 security elements are elements that are detectable using simple equipment such as an ultraviolet lamp, a convex lens, or even a flash of light from a cell phone. This level will include detectable elements such as microprinting, fluorescent inks, as well as fluorescent plates or fibers.

[00012] Finally, level 3 security elements are elements that are detectable by means of sophisticated equipment, for example, such as a spectrofluorometer or an electron microscope. This category mainly includes nano-printed pigments, biometric chips, as well as fluorescent markers not detectable to the naked eye (markers).

[00013] In general, a document incorporates several security elements of different levels.

[00014] Although existing security solutions offer advantages, they are sometimes difficult to implement and / or inspect. Therefore, there is a real need for new security methods that are simple to implement, stable, and thus allow for quick verification of the authenticity of products or documents, while ensuring a high level of security. These methods do not need to be mutually exclusive.

[00015] For this purpose, the invention relates to an optical marking device comprising at least a first layer and a second layer arranged at least partially opposite each other, wherein at least one of said first and second layers comprises Petition 870200161541, dated 12 / 28 / 2020, page 10 / 63 4 / 53 an optically variable element showing a color change between a first color and a second color, said first and second colors being in contrast with respect to a color of the other layer such that when the optically variable element shows said first color, the first layer is visible and when the optically variable element shows said second color, the second layer is visible or when the optically variable element shows said first color, the second layer is visible and when the optically variable element shows said second color, the first layer is visible.

[00016] Thus, the device according to the present invention makes it possible to verify the authenticity of products, such as documents, notably identity, fiduciary or administrative documents, but also such as packaging of medicinal products (mainly tablets) or even luxury products (brand identification).

[00017] According to another functionality of the invention, the device comprises a design provided with said optically variable element.

[00018] According to another functionality of the invention, the device comprises a substrate bearing at least one of the aforementioned first and second layers.

[00019] According to another functionality of the invention, the two layers are in contact with each other.

[00020] According to another functionality of the invention, at least one of the two layers is at least Petition 870200161541, dated 12 / 28 / 2020, page 11 / 63 5 / 53 partially reflective in the visible light spectrum and / or has shades of gray.

[00021] According to another functionality of the invention, at least one of the two layers (2, 3) is diffusing at least partially in the visible light spectrum.

[00022] According to another functionality of the invention, the optically variable element comprises one or more fluorescent compounds.

[00023] According to another embodiment of the invention, the optically variable element comprises one or more compounds of the class 4,4-difluoro-4-bora-3a,4a-diaza-syndacene.

[00024] According to another functionality of the invention, the 4-bora-3a,4a-diazas-indacene compound or compounds used in the present invention may be selected from those of the following formula I: in what R1 is (C1-C6)alkyl, (C5-C6)cycloalkyl, (C5C6)heteroalkyl, phenyl, said phenyl group being optionally replaced by one or more groups selected from (C1-C2)alkyl, hydroxy, R5COO- and halogen; Petition 870200161541, dated 12 / 28 / 2020, p. 12 / 63 6 / 53 R2e R2' are selected independently of hydrogen and (C1-C2)alkyl; R3e R3' are independently selected from hydrogen, aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, alkynyl, said aryl, heteroaryl, cycloalkyl, alkyl, alkenyl and alkynyl being optionally replaced by one or more groups selected from (C1-C4) alkyl, aryl, hydroxy and ferrocene, said aryl group being optionally replaced by one or more groups selected from aryl, (C1-C2)alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl being optionally replaced by a (C1-C2)alkyl group; R4e R4' are independently selected from aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, said aryl, heteroaryl, cycloalkyl, alkyl and alkenyl being optionally replaced by one or more groups selected from (C1-C3)alkyl, aryl, hydroxy and ferrocene, said aryl group being optionally replaced by one or more groups selected from aryl, (C1-C2)alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl being optionally replaced by a (C1-C2)alkyl group; R5 is (C1-C4)alkyl or (C2-C4)alkenyl; R6e R6' are selected independently from halogens, (C1-C4)alkoxy, (C2-C4)alkenyloxy, (C1-C4)alkyl, (C2-C4)alkenyl or aryl, said aryl being optionally replaced by one or more groups selected from (C1-C2)alkyl, hydroxy, R5COO- and halogen. Petition 870200161541, dated 12 / 28 / 2020, p. 13 / 63 7 / 53

[00025] According to another functionality of the invention, the compound or compounds of the class 4,4-difluoro-4bora-3a,4a-diaza-s-indacene are selected from those of formula II: in what R1 is (C1-C6)alkyl, (C5-C6)cycloalkyl, (C5C6)heteroalkyl, phenyl, said phenyl group being optionally replaced by one or more groups selected from (C1-C2)alkyl, hydroxy, R5COO- and halogen; R2e R2' are selected independently of hydrogen and (C1-C2)alkyl; R3e R3' are selected independently of hydrogen and (C1-C3)alkyl; R4e R4' are independently selected from aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, said aryl, heteroaryl, cycloalkyl, alkyl and alkenyl being optionally substituted by one or more groups selected from (C1-C3)alkyl, aryl, hydroxy and ferrocene, said aryl group being optionally substituted by one or more groups selected from aryl, (C1-C2)alkyl, halogen, hydroxy, dimethylamino, Petition 870200161541, dated 12 / 28 / 2020, p. 14 / 63 8 / 53 nitro, the said aryl being optionally replaced by a (C1-C2)alkyl group; R5 is (C1-C4)alkyl or (C2-C4)alkenyl.

[00026] According to another embodiment of the invention, the optically variable element comprises one or more compounds of the β-diketonate difluoroboron (BF2bdks) class.

[00027] According to another functionality of the invention, the compound or compounds of the β-diketonate difluoroboron (BF2bdks) class are selected from those of formula III: in what L1 is an unsaturated aliphatic chain or it is non-existent. L2 is an unsaturated aliphatic chain or it is non-existent. R1 is a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group. R2 is a substituted or unsubstituted aryl group or is a substituted or unsubstituted heteroaryl group, and R3 is selected from hydrogen, a substituted or unsubstituted aryl group, and is a substituted or unsubstituted heteroaryl group. Petition 870200161541, dated 12 / 28 / 2020, p. 15 / 63 9 / 53

[00028] According to another functionality of the invention, the device comprises a polymer incorporating the optically variable element.

[00029] According to another functionality of the invention, the polymer is selected from polycarbonate, polystyrene, polyethylene, polypropylene, poly(ethylene terephthalate), polyacrylate, polymethacrylate, poly(vinyl chloride), polyamides, polyaramids, ethylene vinyl acetate (EVA), polyurethane, thermoplastic polyurethane (TPU), cyanoacrylate, rosin, pine resins, photopolymerizable resins or mixtures thereof.

[00030] According to another functionality of the invention, one of the aforementioned first and second colors of the layer comprising the optically variable element is the complementary color of the color of the other layer.

[00031] According to another embodiment of the invention, the two layers comprise an optically variable element showing a color change, the two optically variable elements being at least partially overlapping and configured in such a way that only the first layer is visible when a first stimulus is applied to the device and only the second layer is visible when a second stimulus is applied to the device.

[00032] According to another functionality of the invention, the device comprises an element configured to polarize light passing through said optical marking device. Petition 870200161541, dated 12 / 28 / 2020, page 16 / 63 10 / 53

[00033] According to another embodiment of the invention, at least one of said first and second layers comprises a mixture of an optically variable element exhibiting a color change between a first color and a second color, and a dye.

[00034] According to another functionality of the invention, the dye is a fluorophore.

[00035] The invention also relates to an identity, fiduciary or administrative document or label comprising at least one optical marking device as described above.

[00036] Other functionalities and advantages of the invention will become clearer upon reading the description given below. This is purely for illustrative purposes and should be read in conjunction with the accompanying drawings, where:

[00037] - Fig. 1 shows a schematic sectional view of an optical marking device according to the present invention;

[00038] - Figs. 2 to 4 show top views, respectively, of a first layer, a second layer and a device according to a first variant embodiment of the invention;

[00039] - Figs. 5 to 7 show top views, respectively, of a first layer, a second layer and a device according to a second variant embodiment of the invention;

[00040] - Figs. 8 to 11 show top views, respectively, of a first layer, of a second Petition 870200161541, dated 12 / 28 / 2020, p. 17 / 63 11 / 53 layer and of a device according to a third variant embodiment of the invention; and

[00041] - Figs. 12 to 15 show a top view of a design on one of the layers of the device according to a fourth variant of the invention. Optical marking device

[00042] The invention relates to an optical marking device for a product, such as a document. The optical marking device is referenced 1 in the figures.

[00043] For the remainder of the description, the term document refers to a set consisting of a substrate and information. The substrate can be of various types, can take various forms, and can comprise a polymer or a mixture of polymers. This substrate, for example, may consist entirely or partially of a polymeric material.

[00044] Examples of documents include, primarily, identity documents such as passports, identity cards, driver's licenses or health cards, but also fiduciary documents such as banknotes and checks, or even administrative documents, for example, such as registration certificates.

[00045] Therefore, documents can be in the form of paper, a book, or a card, and information can be printed on them and / or printed on the surface when it is paper or card, or on the sheets when it is a book. Petition 870200161541, dated 12 / 28 / 2020, page 18 / 63 12 / 53

[00046] Device 1 comprises at least a first layer and a second layer, referred to as optical labeling layers.

[00047] In the figures, device 1 comprises two optical marking layers, referenced 2 and 3.

[00048] It is clear that the invention is not limited to this configuration, and a multilayer configuration, having more than two layers, can be provided.

[00049] In the illustrated embodiments, layers 2 and 3 are exactly superimposed on each other, in direct contact with each other, which is particularly advantageous.

[00050] However, it can be provided that layers 2 and 3 only partially cover each other and / or that they are not in direct contact but, instead, are spaced apart, for example, by the other layers of device 1.

[00051] At least one of the two layers 2, 3 comprises an optically variable element.

[00052] In the first variant embodiment illustrated in Figs. 2 to 4, each of the two layers 2, 3 comprises an optically variable element referenced 4, 5 respectively.

[00053] In the second variant embodiment illustrated in Figs. 5 to 7, only layer 2 comprises an optically variable element, referenced 4.

[00054] In the third variant embodiment illustrated in Figs. 8 to 11, each of the two layers 2, 3 comprises an optically variable element, referenced 4, 5 respectively. Petition 870200161541, dated 12 / 28 / 2020, page 19 / 63 13 / 53

[00055] Each optically variable element shows a color change between a first color and a second color, as will be described later.

[00056] The optical marking device 1 is configured in such a way that when the optically variable element shows the first color, the first layer is visible and when the optically variable element shows said second color, the second layer is visible or when the optically variable element shows the first color, the second layer is visible and when the optically variable element shows said second color, the first layer is visible, as will be described in detail in relation to each variant embodiment of the invention.

[00057] Advantageously, at least one of the two layers comprises a design that is at least partially overlapping with the optically variable element.

[00058] The design may preferably be a symbol, a drawing, a photograph, or a fixed or variable indication that helps to identify the product equipped with the device 1.

[00059] The design, for example, can be printed with ink or varnish or even laser-etched, as will be described in detail later.

[00060] In Fig. 1, device 1 comprises a substrate 11 carrying optical labeling layers 2, 3.

[00061] Substrate 11, for example, is a transparent polymer layer.

[00062] Advantageously, substrate 11 is a layer of polypropylene, polycarbonate, or polyethylene. Petition 870200161541, dated 12 / 28 / 2020, page 20 / 63 14 / 53 controlled thickness (e.g., between 10 µm and 800 µm, preferably a thickness of 50 µm to 600 µm for polycarbonate, 10 µm to 600 µm, and preferably 30 µm to 150 µm for polypropylene and 5 µm to 500 µm, preferably 10 µm for transparent PET. Optically variable element

[00063] Optically variable element means any physicochemical element that exhibits a color change between a first color and a second color as a function of a physicochemical stimulus.

[00064] The physical-chemical stimulus, also called stimulus, can be light irradiation, a change in temperature or pressure, or a change in an observation condition (such as the angle of incidence of observation of the element).

[00065] In the embodiments that will be described in detail, the optically variable element comprises a given concentration of an active substance comprising one or more fluorescent compounds, especially of the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene class (BDPY class) or of the β-diketonate difluoroboron class (BF2bdks), detailed herein below.

[00066] However, the invention is not limited to this type of optically variable element.

[00067] As an example, this could also be a thermochrome, a liquid crystal ink, or an optically variable ink of the type known by the designation OVI (trademark of the company SICPA). Petition 870200161541, dated 12 / 28 / 2020, p. 21 / 63 15 / 53

[00068] Preferably, layer 2 or 3 comprising the optically variable element also comprises a polymer in which the compound or compounds are incorporated into a polymer, and, mainly, into a polymer matrix constituting the document or product in question.

[00069] For the remainder of the description, the compound terms 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, difluoroboron β-diketonate (BF2bdks), and fluorescent dyes will be used interchangeably.

[00070] It should be noted that the active substance can be mixed with one or more types of paints.

[00071] The compounds 4,4-difluoro-4-bora-3a,4a-diazas-indacene are fluorescent dyes, the first synthesis of which was published in 1968 (A. Treibs et al., Justus Liebigs Ann. Chem. 1968, 718, 208). Since then, several other syntheses have been published (e.g., Chem. Eur. J., 2009, 15, 5823; J. Phys. Chem. C, 2009, 113, 11844; Chem. Eur. J., 2011, 17, 3069; J. Phys. Chem. C, 2013, 117, 5373) and a large number of 4,4-difluoro-4bora-3a,4a-diaza-s-indacene compounds are commonly available, for example, from ThermoFisher Scientific (Waltham, MA, USA).

[00072] They possess remarkable absorption and emission properties and, most importantly, have relatively narrow fluorescent excitation and emission bands with high quantum yields φ between 0.5 and 1, which makes them very fluorescent.

[00073] In addition, these compounds possess good photostability as well as high thermal stability. From Petition 870200161541, dated 12 / 28 / 2020, page 22 / 63 16 / 53 In fact, the fluorescent dyes according to the invention are generally stable up to 300°C.

[00074] Due to this high thermal stability, these fluorescent dyes can be easily incorporated into polymer matrices in the molten state and, against all expectations, the performance at the level of absorption and fluorescence emission is not altered by incorporation into a polymer matrix.

[00075] This good stability allows the compound or compounds to be incorporated into a relevant paint, which ensures high stability with respect to photobleaching, in contrast to prior art technologies.

[00076] All 4,4-difluoro-4-bora-3a,4adiaza-s-indacene compounds have an absorption band in the visible spectrum, and the color perceived by the naked eye corresponds to the complementary color of the absorbed color. For example, a compound that absorbs around 480 to 490 nm, which corresponds to a green / blue color, will appear to the naked eye in orange / red tones.

[00077] This property thus makes it possible to obtain level 1 security elements.

[00078] With regard to fluorescence properties, all compounds of the 4,4-difluoro-4-bora-3a,4adiaza-s-indacene class according to the invention possess excitation bands in the ultraviolet (UV) and emission bands in the visible. Therefore, they can be excited primarily by means of a UV lamp emitting between 100 nm and 400 nm. Petition 870200161541, dated 12 / 28 / 2020, p. 23 / 63 At 17 / 53 nm, the fluorescence can be detected with the naked eye, making it possible to obtain level 2 safety elements.

[00079] Finally, the emission wavelength can be determined using a single-grass low-resolution spectrofluorometer or fluorometer (photodiode or photomultiplier tube detection), which provides the safety elements according to the present invention with level 3 safety.

[00080] The 4-bora-3a,4a-diazas-indacene compound or compounds used in the present invention may be selected from those of the following formula I: in what R1 is (C1-C6)alkyl, (C5-C6)cycloalkyl, (C5C6)heteroalkyl, phenyl, said phenyl group being optionally replaced by one or more groups selected from (C1-C2)alkyl, hydroxy, R5COO- and halogen; R2e R2' are selected independently of hydrogen and (C1-C2)alkyl; R3 and R3' are independently selected from hydrogen, aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, alkynyl, said aryl, heteroaryl, cycloalkyl, alkyl, alkenyl and alkynyl being optionally Petition 870200161541, dated 12 / 28 / 2020, p. 24 / 63 18 / 53 substituted by one or more groups selected from (C1-C4) alkyl, aryl, hydroxy and ferrocene, said aryl group optionally being substituted by one or more groups selected from aryl, (C1-C2) alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl group optionally being substituted by a (C1-C2) alkyl group; R4e R4' are independently selected from aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, said aryl, heteroaryl, cycloalkyl, alkyl and alkenyl being optionally replaced by one or more groups selected from (C1-C3)alkyl, aryl, hydroxy and ferrocene, said aryl group being optionally replaced by one or more groups selected from aryl, (C1-C2)alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl being optionally replaced by a (C1-C2)alkyl group; R5 is (C1-C4)alkyl or (C2-C4)alkenyl; R6e R6' are selected independently from halogens, (C1-C4)alkoxy, (C2-C4)alkenyloxy, (C1-C4)alkyl, (C2-C4)alkenyl or aryl, said aryl being optionally replaced by one or more groups selected from (C1-C2)alkyl, hydroxy, R5COO- and halogen.

[00081] Preferred compounds of formula I are those in which one or more of R1, R2, R2', R3, R3', R4, R4', R5, R6 and R6' are defined as follows: R1 is a phenyl substituted with one or more groups selected from methyl, fluorine, hydroxyl, acetyl and Petition 870200161541, dated 12 / 28 / 2020, page 25 / 63 19 / 53 methacrylate, preferably methyl, fluorine, hydroxy and acetyl, and more preferably methyl or fluorine; R2e and R2' are selected independently from hydrogen and methyl urns; R3 and R3' are independently selected from hydrogen, (C1-C3)alkyl, vinyl, aryl, heteroaryl, adamantil, said vinyl and aryl being optionally substituted with one or more groups selected from phenyl, (C1-C2)alkyl, said phenyl being optionally substituted with one or more groups selected from (C1-C2)alkyl, hydroxy, bromo, nitro, dimethylamine, preferably hydrogen, methyl, ethyl, n-propyl, vinyl, aryl, heteroaryl, adamantil, said vinyl and aryl being optionally substituted with one or more groups selected from phenyl, (C1-C2)alkyl, said phenyl being optionally substituted with one or more groups selected from (C1-C2)alkyl, hydroxy, bromo, nitro, dimethylamine, more preferably, R3 and R3' are independently selected from ethyl, n-propyl, methyl, vinyl, phenyl, phenantryl, naphthyl, pyrenyl, thiophenyl, benzofuranil, the aforementioned vinyl,aryl and naphthyl groups optionally replaced with one or more methyl, hydroxy, bromo, nitro, and dimethylamino groups; R4e R4' are independently selected from methyl, vinyl, aryl, heteroaryl, adamantil, said vinyl and aryl being optionally replaced with one or more groups selected from phenyl, (Cl Petition 870200161541, dated 12 / 28 / 2020, p. 26 / 63 20 / 53 C2)alkyl, said phenyl being optionally substituted with one or more groups selected from (ClC2)alkyl, hydroxy, bromo, nitro, dimethylamine, preferably R4 and R4' are selected independently from methyl, vinyl, phenyl, phenanthryl, naphthyl, pyrenyl, thiophenyl, benzofuranyl, said vinyl, aryl and naphthyl being optionally substituted with one or more methyl, hydroxy, bromo, nitro and dimethylamino; R5 is methyl or ethenyl. R6e R6' are independently selected from fluorine, (C1-C4) alkoxy, (C2-C4) alkenyloxy, (C1-C4) alkyl, (C2-C4) alkenyl or aryl, said aryl being optionally substituted with one or more groups selected from (C1-C2) alkyl, hydroxy, R5COO“ and halogen, preferably R6e R6' are fluorine.

[00082] According to a particular embodiment, the 4,4-difluoro-4-bora-3a,4a-diaza-syndacene compound or compounds used in the present invention may be selected from those of the following formula II: in what R1 is (C1-C6)alkyl, (C5-C6)cycloalkyl, (C5-C6)heteroalkyl, phenyl, said phenyl group being optionally substituted with one or more groups Petition 870200161541, dated 12 / 28 / 2020, p. 27 / 63 21 / 53 selected from (C1-C2)alkyl, hydroxy, R5COO“ and halogen; R2e R2' are selected independently from hydrogen and (C1-C2)alkyl; R3e R3' are selected independently of hydrogen and (C1-C3)alkyl; R4e R4' are independently selected from aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, said aryl, heteroaryl, cycloalkyl, alkyl and alkenyl being optionally substituted with one or more groups selected from (C1-C3)alkyl, aryl, hydroxy and ferrocene, said aryl group being optionally substituted with one or more groups selected from aryl, (C1-C2)alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl being optionally substituted with an (C1-C2)alkyl group; R5 is (C1-C4)alkyl or (C2-C4)alkenyl.

[00083] Preferred compounds of formula II are those in which one or more of R1, R2, R2', R3, R3', R4, R4' and R5 are defined as follows: R1 is a phenyl substituted with one or more groups selected from methyl, fluorine, hydroxyl, acetyl and methacrylate, preferably methyl, fluorine, hydroxyl and acetyl and, more preferably, methyl or fluorine; R2e and R2' are selected independently from hydrogen and methyl; R3e R3' are selected independently from hydrogen, methyl, ethyl, n-propyl and preferably ethyl 1; Petition 870200161541, dated 12 / 28 / 2020, page 28 / 63 22 / 53 R4e R4' are independently selected from methyl, vinyl, aryl, heteroaryl, adamantil, said vinyl and aryl being optionally substituted with one or more groups selected from phenyl, (C1C2)alkyl, said phenyl being optionally substituted with one or more groups selected from (C1C2)alkyl, hydroxy, bromo, nitro, dimethylamine, preferably R4e R4' are independently selected from methyl, vinyl, phenyl, phenanthracenyl, naphthalenyl, pyrenyl, thiophenyl, benzofuranil, said vinyl, aryl and naphthalenyl being optionally substituted with one or more methyl, hydroxy, bromo, nitro and dimethylamino; R5 is methyl or ethenyl.

[00084] Particularly preferred compounds of formula II are those in the following table: No. Fluorescent dye 1 \^N * - —\ / —\\ “u- 2 TIDO 7---λ--- 3 f OH Petition 870200161541, dated 12 / 28 / 2020, p. 29 / 63 23 / 53 4 0 o'^ 0 Çn. / B \ / f2 \ 5 jlX Çn. Ο Ο 6 F IT \F F / / F2 ' 7 / Ô\ r r X / B \ / Λ O o R = Me, Et, n-Pr 8 Â^o L / o=\ JAz 9 0 -^o 0 / Çn. ,n~<7 \ __( / B \ V γ\λ fz y~ / \ Mu Cv Petição 870200161541, de 28 / 12 / 2020, pág. 30 / 63 24 / 53 10 V-N, ,N¾ / χχ F2 0O 00 00 Χχ 00 11 xX OXXO o o o o Br Br 12 O 0 'On. = / B \ F2 / = o o o o 13 χχ yN.BW 0 F2 0s R = n-Pr 14 Ox R^ / ^P =νβ·ν = O F2 O R = Et Petição 870200161541, de 28 / 12 / 2020, pág. 31 / 63 25 / 53 15 YY R—f'' R >ν-β'νΎ O F2 \JS R = Me 16 F f^L / F ϊ T F^y^ F F2 ' O HO 17 F F\ / L / F JT \FT f / Çn. / B \ yr ry 18 -<2H Λ 19 F F Z --F IT F'yT Τν. / B \ ri F2 Ó 0 Petição 870200161541, de 28 / 12 / 2020, pág. 32 / 63 26 / 53 20 F K / Pf 1 T F^y^F \^hk ,Ν-# 0 0 HO OH 21 F F\P^F J T .f^V^F / 0n. ,n0 / B \ r^· F2 HO / \ OH O2 N N°2 no2 o2n 22 Δ V / v? R = Me, Et, n-Pr 23 θά, ívQ: R = H, Me, Et, n-Pr 24 O , 0Ό 25 J0 çÓq / A F: Λ=\ ζΡ X) Petition 870200161541, dated 12 / 28 / 2020, pp. 33 / 63 27 / 53 26 AAA- 27 Ά 28 A VN. / B \ ° 7 Fj ( 0 QM 29 A \íN N-^ / B Λ rr? Ο Ί 30 FIJ \F^ F; AF= AV w \ / Petition 870200161541, dated 12 / 28 / 2020, pp. 34 / 63 28 / 53 31 FRA 1J Çn. / F 32 ''íj Λ / f2\ Petition 870200161541, dated 12 / 28 / 2020, pp. 35 / 63 29 / 53 39 'M'

[00085] For the description of the compounds used in the present invention, the terms and expressions used herein, unless stated otherwise, shall be interpreted in accordance with the following definitions.

[00086] The term halogen denotes fluorine, chlorine, bromine, or iodine. Preferred halogen groups are fluorine and bromine, fluorine being particularly preferred.

[00087] The term alkyl denotes a hydrocarbon radical of the formula CnH2n+i, linear or branched, where n is an integer greater than or equal to 1. Preferred alkyl groups are linear or branched (C1-C6)alkyl groups.

[00088] The term alkenyl denotes an unsaturated alkyl group, linear or branched, comprising one or more carbon-carbon double bonds. Suitable alkenyl groups comprise from 2 to 6 carbon atoms, preferably from 2 to 4 carbon atoms, and even more preferably 2 or 3 carbon atoms. Non-limiting examples of alkenyl groups are ethenyl (vinyl), 2-propenyl (allyl), 2-butenyl and 3-butenyl, ethenyl and 2-propenyl being preferred.

[00089] The term cycloalkyl, alone or as part of another group, denotes a saturated monocyclic, bicyclic, or tricyclic hydrocarbon radical having 3 to 12 carbon atoms, mainly 5 to 10 carbon atoms, more particularly 6 to 10 carbon atoms. Radicals Petition 870200161541, dated 12 / 28 / 2020, pp. 36 / 63 Suitable 30 / 53 cycloalkyl groups include, but are not limited to, cyclopentyl, cyclohexyl, norbornyl, adamantil, primarily cyclohexyl and adamantil. Preferred cycloalkyl groups include cyclohexyl, adamant-1-yl and adamant-2-yl.

[00090] The term aryl denotes a polyunsaturated, aromatic, monocyclic (e.g., phenyl) or polycyclic (e.g., naphthyl, anthracenyl, phenanthracenyl, pyrenyl) hydrocarbon radical. Preferred aryl groups include phenyl, naphthyl, anthracenyl, phenanthracenyl, pyrenyl.

[00091] The term heteroaryl denotes an aromatic ring having from 5 to 12 carbon atoms in which at least one carbon atom is replaced by an oxygen, nitrogen, or sulfur atom or by -NH, said nitrogen and sulfur atoms may optionally be oxidized and said nitrogen atom may optionally be quaternized, or a cyclic system containing 2 to 3 fused rings each typically containing 5 or 6 atoms and at least one of said rings is aromatic, at least one carbon atom of at least one aromatic ring being replaced by an oxygen, nitrogen, or sulfur atom or by -NH, said nitrogen and sulfur atoms may optionally be oxidized and said nitrogen atom may optionally be quaternized. Examples of heteroaryl groups include furanyl, thiophenyl, pyrrolyl, pyridinyl, and benzofuranyl.

[00092] The compounds used in the present invention can be synthesized by methods known to an expert in Petition 870200161541, dated 12 / 28 / 2020, pp. 37 / 63 31 / 53 technique. Reference can be made primarily to the work of A. Loudet et al. (Chern. Rev. 2007, 107, 48914932).

[00093] According to another embodiment, the optically variable element comprises a fluorescent composition comprising a polymer matrix incorporating a compound of the β-diketonate (BF2bdk) difluoroboron class selected from compounds of the following formula III: F\F CT in what L1 is an unsaturated aliphatic chain or it is non-existent. L2 is an unsaturated aliphatic chain or it is non-existent. R1 is a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group. R2 is a substituted or unsubstituted aryl group or is a substituted or unsubstituted heteroaryl group, and R3 is selected from hydrogen, a substituted or unsubstituted aryl group, and is a substituted or unsubstituted heteroaryl group.

[00094] Preferred compounds of the β-diketonate difluoroboron class of formula I are those in which one or more of L1, L2, R1, R2, and R3 are defined as follows: Petition 870200161541, dated 12 / 28 / 2020, pp. 38 / 63 32 / 53 L1 is an unsaturated aliphatic chain, preferably C2 to C8 or non-existent. L2 is an unsaturated aliphatic chain, preferably C2 to C8 or non-existent. R1 is a substituted or unsubstituted aryl group, preferably a substituted or unsubstituted aryl group with at least one electron-donating or electron-accepting group. R2 is a substituted or unsubstituted aryl group, preferably a substituted or unsubstituted aryl group with at least one electron-donating or electron-accepting group, and R3 is selected from hydrogen and a substituted or unsubstituted aryl group.

[00095] Preferred compounds of the β-diketonate difluoroboron class of formula I are those in which one or more of L1, L2, R1, R2, and R3 are defined as follows: L1 is an unsaturated aliphatic chain, C2 to C4 or non-existent. L2 is an unsaturated aliphatic chain, C2 to C4 or non-existent. R1 is a substituted or unsubstituted aryl group with at least one group selected from hydroxyl, alkoxy, alkyl, aryl, dialkylmino, thioalkoxy, halogen, R2 is a substituted or unsubstituted aryl group with at least one group selected from hydroxyl, alkoxy, alkyl, aryl, dialkylmino, thioalkoxy, halogen, and R3 is selected from hydrogen and an unsubstituted aryl group. Petition 870200161541, dated 12 / 28 / 2020, pp. 39 / 63 33 / 53

[00096] Preferred compounds of the β-diketonate difluoroboron class of formula I are those in which one or more of L1, L2, R1, R2, and R3 are defined as follows: L1 is an unsaturated aliphatic chain, C2 to C4 or non-existent. L2 is an unsaturated aliphatic chain, C2 to C4 or non-existent. R1 is a substituted or unsubstituted aryl group with at least one group selected from hydroxy, (C1-C4)alkoxy, (C1-C8)alkyl, aryl, (C1-C4)dialkylmino, (C1-C4)thioalkoxy, halogen, preferably fluorine, R2 is a substituted or unsubstituted aryl group with at least one group selected from hydroxy, C1 to C4 alkoxy, C1 to C8 alkyl, aryl, C1 to C4 dialkylmino, C1 to C4 thioalkoxy, halogen, preferably fluorine, and R3 is a hydrogen atom.

[00097] Preferred compounds of the β-diketonate difluoroboron class of formula I are those in which one or more of L1, L2, R1, R2, and R3 are defined as follows: L1 is an unsaturated aliphatic chain, C2 is either non-existent or not. L2 is an unsaturated aliphatic chain, C2 or non-existent, R1 is an aryl group, preferably phenyl, biphenyl or naphthyl, unsubstituted or substituted with at least one group selected from hydroxy, (C1-C4)alkoxy, preferably methoxy, (C1-C8)alkyl, preferably tert-butyl, aryl, (C1-C4)alkylmino, preferably dimethylamino, Petition 870200161541, dated 12 / 28 / 2020, pp. 40 / 63 34 / 53 R2 is an aryl group, preferably phenyl, biphenyl or naphthyl, unsubstituted or substituted with at least one group selected from hydroxy, (C1-C4)alkoxy, preferably methoxy, (C1-C8)alkyl, preferably tert-butyl, aryl, (C1-C4)alkylmino, preferably dimethylamino, and R3 is a hydrogen atom.

[00098] Preferred compounds of the β-diketonate difluoroboron class are those of the following formula III2: Where R1, R2 and R3 are as defined in formula I.

[00099] Preferred compounds of the β-diketonate difluoroboron class are those of the following formula III3: where L1, R1, R2 and R3 are as defined in the formula III. [000100] Preferred compounds of the β-diketonate difluoroboron class are those of the following formula III4: Petition 870200161541, dated 12 / 28 / 2020, pp. 41 / 63 35 / 53 where L2, R1, R2 and R3 are as defined in formula III. [000101] Particularly preferred compounds of the β-diketonate difluoroboron class of formula III are The data below: Compound 1 F\ F CF Compound 3 F\ F b·^ O| ^0 Compound 5 F\ F CF ^0 Compound 7 Compound 2 FF r / CF ^0 ΓΎ^ MeCY Compound 4 F\ F CF Xj^ MeO^ Compound 6 F\ F αΧυ Compound 8 Petition 870200161541, dated 12 / 28 / 2020, pp. 42 / 63 36 / 53 Compound 11 Compound 12 Compound 14 [000102] The term alkyl denotes a hydrocarbon radical of the formula CnH2n+i, linear or branched, where n is an integer greater than or equal to 1. Preferred alkyl groups are linear or branched (C1-C6)alkyl groups. [000103] The term alkenyl denotes an unsaturated alkyl group, linear or branched, comprising one or more Petition 870200161541, dated 12 / 28 / 2020, pp. 43 / 63 37 / 53 carbon-carbon double bonds. Suitable alkenyl groups comprise from 2 to 6 carbon atoms, preferably from 2 to 4 carbon atoms, and even more preferably 2 or 3 carbon atoms. Non-limiting examples of alkenyl groups are ethenyl (vinyl), 2-propenyl (allyl), 2-butenyl and 3-butenyl, ethenyl and 2-propenyl being preferred. [000104] The term cycloalkyl, alone or as part of another group, denotes a saturated monocyclic, bicyclic or tricyclic hydrocarbon radical having 3 to 12 carbon atoms, mainly 5 to 10 carbon atoms, more particularly 6 to 10 carbon atoms. Suitable cycloalkyl radicals include, but are not limited to, cyclopentyl, cyclohexyl, norbornyl, adamantyl, mainly cyclohexyl and adamantyl. Preferred cycloalkyl groups include cyclohexyl, adamant-1-yl and adamant-2-yl. [000105] The term aryl denotes a polyunsaturated, aromatic, monocyclic (e.g., phenyl) or polycyclic (e.g., naphthyl, anthracenyl, phenanthracenyl, etc.) hydrocarbon radical. Preferred aryl groups include phenyl, naphthyl, anthracenyl, phenanthracenyl, pyrenyl. [000106] The term heteroaryl denotes an aromatic ring having from 5 to 12 carbon atoms in which at least one carbon atom is replaced by an oxygen, nitrogen or sulfur atom or by -NH, said nitrogen and sulfur atoms may optionally be oxidized and said nitrogen atom may optionally be Petition 870200161541, dated 12 / 28 / 2020, pp. 44 / 63 38 / 53 quaternized, or a cyclic system containing 2 to 3 fused rings, each typically containing 5 or 6 atoms, and at least one of said rings is aromatic, at least one carbon atom of at least one aromatic ring being replaced by an oxygen, nitrogen, or sulfur atom or by -NH, said nitrogen and sulfur atoms may optionally be oxidized and said nitrogen atom may optionally be quaternized. Examples of heteroaryl groups include furanyl, thiophenyl, pyrrolyl, pyridinyl, and benzofuranyl. [000107] The term halogen denotes fluorine, chlorine, bromine, or iodine. Preferred halogen groups are fluorine and bromine, fluorine being particularly preferred. [000108] The term alkoxy denotes an alkyl group bonded to an oxygen atom. [000109] The term alkenyloxy denotes an alkenyl group bonded to an oxygen atom. [000110] Thus, when layer 2, 3 comprising the optically variable element is deposited on a light background, the intrinsic color is observed (that is, the complementary color of the color absorbed by the fluorescent compound or compounds). [000111] On the other hand, against a dark background, the fluorescence color due to fluorescent compounds is observed. [000112] The physical-chemical stimulus consists of positioning device 1 on a light background and then on a dark background, or, conversely, on a dark background and then on a light background. Petition 870200161541, dated 12 / 28 / 2020, pp. 45 / 63 39 / 53 [000113] The incorporation can be carried out in all types of polymer, for example, such as polycarbonate, polystyrene, polyethylene, polypropylene, poly(ethylene terephthalate), polyacrylate, polymethacrylate, poly(vinyl chloride), polyamides, polyaramids, ethylene vinyl acetate (EVA), polyurethane, thermoplastic polyurethane (TPU), cyanoacrylate, pitch, pine resins, photopolymerizable resins or mixtures thereof. Preferably, the incorporation can be carried out in a polymer selected from polycarbonate, thermoplastic polyurethane and photopolymerizable resins, preferably from polycarbonate and thermoplastic polyurethane, most preferably the polymer is polycarbonate. [000114] The amount of fluorescent dye to be incorporated is that necessary to detect the absorbance and fluorescence properties. The fluorescent dyes according to the invention have the advantage of allowing the detection of the properties even when they are incorporated into the polymer in very small quantities. [000115] In fact, amounts of fluorescent dyes from 0.0001 to 5% by weight relative to the total weight of the polymer are sufficient for detection, preferably amounts from 0.001 to 2% by weight relative to the total weight of the polymer and even more preferably amounts from 0.01 to 1% by weight relative to the total weight of the polymer. [000116] The quantities of fluorescent dyes will be adapted by a technician versed in the subject as a Petition 870200161541, dated 12 / 28 / 2020, pages 46 / 63 40 / 53 function of polymer formation and the required visual effect. [000117] Each layer comprising an optically variable element is advantageously prepared by techniques known to a person skilled in the art, for example, such as winding, extrusion, calendering, or extrusion calendering. These techniques will be selected as a function of the polymer used. As an example, if the polymer is a polycarbonate or a thermoplastic polyurethane, the principle of extrusion calendering will be preferred. An assembly of layers in the sense of the present invention, for example, can be obtained by winding two or more layers of polymer incorporating one or more fluorescent dyes. [000118] Advantageously, layer 2, 3 notably has a thickness of 10 pm to 800 pm, preferably a thickness of 50 pm to 600 pm, for polycarbonate, 10 pm to 600 pm, and preferably 30 pm to 150 pm for polypropylene and 5 pm to 500 pm, preferably 10 pm for PET, wherein a paint thickness of 0.1 pm to 200 pm, preferably 1 pm to 100 pm, is added. [000119] When the layer has a thickness of less than 0.100 mm, it is also called a film and will find quite particular application in the case of flat products, mainly documents and more particularly identity, fiduciary or administrative documents, and may be applied to at least part of one of the faces of the product. First variant Petition 870200161541, dated 12 / 28 / 2020, pp. 47 / 63 41 / 53 [000120] As can be seen in Figs. 2 to 4, the optical marking device 1 comprises a first optical marking layer and a second optical marking layer 3. [000121] In Fig. 4, layer 3 is superimposed on layer 2. [000122] Each of layers 2, 3 comprises an optically variable element 4, 5. [000123] The first layer 2 comprises a project 9 in the form of a disk. [000124] Disk 9 incorporates the optically variable element 4 of layer 2. [000125] For example, it is a paint or varnish incorporating the active substance. [000126] The second layer 3 comprises a drawing 10 in the shape of a triangle. [000127] Triangle 10 incorporates optically variable element 5 of layer 2. [000128] For example, it is a paint or varnish incorporating the active substance. [000129] Drawing 10 covers drawing 9. [000130] Drawings 9 and 10 are in the center of their respective layers 2 and 3. [000131] It is clear that the invention is not limited to this configuration and the designs, on the other hand, can be decentralized. [000132] Each of the optically variable elements 4, 5 comprises one or more fluorescent compounds such as Petition 870200161541, dated 12 / 28 / 2020, pages 48 / 63 42 / 53 described above, preferably incorporated into a polymer. [000133] In Fig. 2, a first half 2-1 of the first layer 2 comprising a first half 9-1 of disk 9 is shown against a light background. [000134] A second 2-2 half of the first layer 2 comprising a second 9-2 half of disc 9 is shown against a dark background. [000135] In Fig. 3, a first half 3-1 of the second layer 3 comprising a first half 10-1 of triangle 10 is shown against a light background. [000136] A second 3-2 half of the second layer 3 comprising a second 10-2 half of triangle 10 is shown against a dark background. [000137] The intrinsic colors of layers 2, 3 and advantageously their luminous intensities are selected in such a way that, against a light background, it is drawing 10 of the second layer 3 that is visible, whereas against a dark background it is drawing 9 of the first layer 2 that is visible. [000138] For example, the first half 9-1 is pink (represented by the dashed lines), which, as already stated, corresponds to the intrinsic color of layer 2. [000139] The second half 9-2 is green (represented by dashed lines), which, as already stated, corresponds to the fluorescence color of layer 2. Petition 870200161541, dated 12 / 28 / 2020, pp. 49 / 63 43 / 53 [000140] The first half 10-1 is blue (represented as parallel dashed lines), which, as already stated, corresponds to the intrinsic color of layer 3. [000141] The second half 10-2 is red (represented as parallel dashed lines, in a different direction from that of half 10-1), which, as already stated, corresponds to the fluorescence color of layer 3. [000142] In Fig. 4, a first half 1-1 of device 1 is positioned on the light background where a second half 1-2 of device 1 is positioned on the dark background. [000143] Against the light background, it is the second layer 3 that is visible and the blue triangle 10-2 is observed. [000144] Against the dark background, it is the first layer 2 that is visible and the green circle 9-1 is observed. [000145] Note that the optical effect obtained is made possible by the concentration in the second layer 3 of the active substance of the ink or varnish used for the production of the drawing, selected to minimize its visibility against a light background, as well as by the choice of the active substance in the drawing of the first layer 2, whose fluorescence color is contrasting with that of layer 3, advantageously being of complementary color (in subtractive synthesis) to that of the second layer 3. [000146] Thus, if an operator passes a product equipped with marking device 1 over a light background and then a black background, he observes the blue triangle and then the green circle. Petition 870200161541, dated 12 / 28 / 2020, pages 50 / 63 44 / 53 [000147] The passage over the white background or the dark background in this case is the physical stimulus that allows the color change of the marking device 1. [000148] It should be added that, advantageously, the intrinsic colors of the first layer 2 and the second layer 3 respectively are selected in such a way that layer 2 is visible only on a white background. [000149] Furthermore, the fluorescence colors are selected so that only layer 3 is visible (dark background). For example, the fluorescence color of the first layer is complementary to that of the second layer, as already noted. In fact, layer 3 filters out all wavelengths of radiation below its color. [000150] Note that changing from a white background to a black background is a special case, but of course other background colors can be used. [000151] The following table summarizes the different colors of device 1. Layer 2 (bottom) Color pair A / B Layer 3 (top) Color pair C / D Intrinsic color AC Perceived device color on a light background A Color BD Petition 870200161541, dated 12 / 28 / 2020, pp. 51 / 63 45 / 53 Fluorescence: Color of the device perceived against a dark background. D Second variant [000152] As can be seen in Figs. 5 to 7, the optical marking device 1 comprises a first optical marking layer 2 and a second optical marking layer 3. [000153] In Fig. 7, layer 3 is superimposed on layer 2. [000154] Only the first layer 2 comprises an optically variable element 4. [000155] As can be seen in Fig. 5, the first layer 2 is identical to the first layer 2 detailed in relation to the first variant embodiment. [000156] The second layer 3 does not have an optically variable element. [000157] The second layer 3 has a color, obtained by all techniques known to a technician versed in the subject (mass dyeing, varnishing, for example). [000158] The color is, for example, red. [000159] Against a light background, the color appears light red, and against a black background the color appears dark red. [000160] As can be seen in Fig. 7, a first half 1-1 of device 1 is placed at the bottom. Petition 870200161541, dated 12 / 28 / 2020, pp. 52 / 63 46 / 53 clear in which a second half 1-2 of device 1 is placed on the dark background. [000161] Against the light background, only the second layer 3, red, is visible. [000162] Against the dark background, the first layer 2 is visible and the green semicircle 9-2 is observed against a dark red background. [000163] The transition from a white background to a dark background in this case is the physical stimulus that allows the color change of the marking device 1. [000164] Note that the optical effect obtained is made possible by the concentration of the active substance in the ink or varnish used to produce the design 9 of the first layer 2, selected to minimize its visibility against a light background, as well as by the choice of the color of the second layer 3, whose color is in contrast with the fluorescence color, and preferably with a color corresponding to the complementary color of the fluorescence used in the first layer 2. Third variant [000165] According to this third variant, marking device 1 comprises a first layer 2 and a second layer 3. [000166] The second layer 3 is identical to the second layer 3 detailed in relation to the first variant embodiment. [000167] The first layer 2 comprises, similarly to the first variant embodiment, a design 9 comprising an optically variable element. Petition 870200161541, dated 12 / 28 / 2020, pages 53 / 63 47 / 53 [000168] The first layer 2 or second layer 3 is at least partially reflective in the visible light spectrum. [000169] For this purpose, layer 2 can be a metallized polymer layer (polycarbonate, polypropylene, PET), or a metallic layer directly. Layer 2 can also comprise micro-mirrors. [000170] According to other variants not shown, device 1 also comprises substrate 11, which is metallized, or layer 2 is coated with a layer of metallic reflections that have ink. [000171] According to this third variant, the stimulus is the switching of the observation angle of device 1, as a function of the light environment (i.e., light or dark environment). [000172] Depending on the viewing angle, there is minimization or, on the other hand, maximization of light admission, which allows the color of device 1 to change. [000173] As can be seen in Fig. 8, when the observation direction D extends in a first direction, for example, a direction N normal to a plane P of device 1, the second layer 3 shows the intrinsic color. [000174] As can be seen in Fig. 9, when the observation direction D forms a non-zero angle with the plane P, the second layer 3 shows the fluorescence color. [000175] As can be seen in Fig. 10, when the observation direction D extends in the N direction, the blue triangle 10 of the second layer 3 is visible. Petition 870200161541, dated 12 / 28 / 2020, pages 54 / 63 48 / 53 [000176] As can be seen in Fig. 11, when the D direction forms a non-zero angle with the N direction, the green disk 9 of the first layer 2 is visible. [000177] According to a variant that is not shown, the first layer 2 comprises shades of gray. [000178] Note that the optical effect obtained is made possible by the concentration of the active substance to produce the design of the second layer 3 in such a way as to minimize its visibility when observed normally, by the choice of the color of the first layer 2, which is contrasting with the complementary color of the fluorescence of the active substance of the second layer 3, and preferably the complementary color, as well as the inversion angle according to a gray scale of the reflective surface (the more reflective the surface (low gray level), the smaller the inversion angle, and vice versa). [000179] According to another variant not shown, the optical effect of color inversion can be obtained when at least one of layers 2, 3 has optical diffusion properties. [000180] Preferably, layer 2, 3 having diffusion properties is, for example, matte. [000181] In this case, depending on the angle of observation, diffusion prevents fluorescence, and only the intrinsic color appears. Another variant [000182] Advantageously, the optical marking device 1 comprises a polarizing film (not shown). Petition 870200161541, dated 12 / 28 / 2020, pages 55 / 63 49 / 53 [000183] The polarization film can consist of layer 2 or substrate 11, for example. [000184] In this case, substrate 11 is not necessarily transparent, in contrast to the variants described above. [000185] The polarization of light allows the visualization of one of the layers 2 and then of the other layer 3. Mix with a dye. [000186] According to another variant, each of the layers incorporating an optically variable element or at least one of the layers incorporating an optically variable element may comprise a dye mixed with the optically variable element. [000187] For example, it is a colored ink incorporating the active substance. [000188] Depending on the nature of the dye and its concentration, it is possible to alter the intrinsic color and / or fluorescence color and / or the UV color of the device 1. [000189] Note that dye means any molecule capable of coloring, regardless of its size, its preparation, and the conditions under which the molecule acquires the ability to color. [000190] In particular, the dye can be dissolved or dispersed (like a pigment, for example). [000191] In particular, the dye can be goniochromic, photochromic, thermochromic or piezochromic. [000192] Figs. 12 to 15 show the circular design 9 of layer 2 according to one of the first three variants already described. Petition 870200161541, dated 12 / 28 / 2020, pp. 56 / 63 50 / 53 [000193] Circular design 9 comprises a mixture of the active substance based on 4,4-difluoro-4bora-3a,4a-diaza-s-indacene compounds of the BDPY class, and a dye. [000194] The dye has a minimum of transparency. [000195] According to one possibility, the dye does not possess fluorescent properties, and has the effect of altering the intrinsic color (against a light background) without changing the fluorescent color. [000196] This effect is achieved by adding the color of the dye and the intrinsic color of the active substance. [000197] Thus, for example, if design 9 with the active substance and without a dye has an intrinsic blue color and a red fluorescence color, then design 9 comprising the mixture of a yellow dye and the active substance has an intrinsic green color, the fluorescence color remaining red. [000198] Fig. 12 shows drawing 9 with the active substance and without a dye against a light background: it is the blue color that appears (dashed). [000199] Fig. 13 shows drawing 9 with the active substance and without a dye against a dark background: it is the red color that appears (opposite dashed line). [000200] Fig. 14 shows drawing 9 comprising the mixture of the active substance and the yellow dye against a light background: it is the green color that appears (dots). [000201] Fig. 15 shows drawing 9 comprising the mixture of the active substance and the yellow dye against a Petition 870200161541, dated 12 / 28 / 2020, pages 57 / 63 51 / 53 dark background: this is the red color that appears (with dashed lines identical to those in Fig. 13). [000202] According to another possibility, the addition of the colors (against a light background) of the intrinsic color and the dye color can completely obscure the intrinsic color. [000203] Thus, for example, if design 9 with the active substance and without a dye has an intrinsic pink color and a red fluorescence color, then design 9 comprising the mixture of a blue dye and the active substance has an intrinsic blue color, the fluorescence color remaining red. [000204] This occurs when the color of the added non-fluorescent dye covers, at least to the naked eye, the intrinsic color of the active substance. [000205] According to another possibility, the dye is a fluorophore that does not belong to the BDPY class and has excitation and fluorescent emission bands different from those of the active substance. Then it is possible to alter the color emitted under ultraviolet radiation by the design comprising the mixture of the active substance and the fluorescent dye. [000206] Note that the color against a dark background is not altered since the fluorescence of the added dye is only visible under UV light. Under UV illumination, there are mixing phenomena between the fluorescence color of the active substance BDPY and the color of the added fluorophore dye. Petition 870200161541, dated 12 / 28 / 2020, pages 58 / 63 52 / 53 [000207] It is possible, for example, to obtain white fluorescence under UV light by mixing an intrinsically green active substance with a yellow fluorescent dye. [000208] According to another possibility, the fluorophore dye makes it possible to alter the intrinsic color as well as the fluorescence color. This is possible in the case of mixing several compounds of the BDPY class. Applications [000209] The invention also relates to an identity, fiduciary or administrative document or label, comprising at least one optical marking device 1. [000210] For example, the document could be an identity card, a passport, a license, a certificate, a diploma, a checkbook, a registration, a stamp, a seal, a visa, a bank card, a banknote. [000211] The design may be a national symbol, or a company or national symbol, a logo associated with a trademark, or even a fixed or variable statement, or a nominal value. [000212] Marking device 1 occupies the entire document or part of the document. Advantages [000213] As is clear from the preceding description, the marking device according to the present invention offers the advantage of effective document security primarily through physical stimuli. Petition 870200161541, dated 12 / 28 / 2020, pages 59 / 63 53 / 53 chemicals, such as passing over a light background and then a dark background, or changing the angle of observation. [000214] Any agent will be able to undertake a simple and quick verification of the document, as it is not necessary to be provided with expensive equipment, a simple movement being sufficient for the verification. [000215] The 4,4-difluoro-4-bora-3a,4a-diaza-syndacene class of fluorescent compounds and / or the β-diketonate difluoroboron (BF2bdks) class ensure a simple manufacturing method for marking device 1, as they are easily incorporated into a polymer and exhibit good thermal stability, which also makes it possible to perform all the steps necessary for manufacturing the document in which one or more marking devices 1 are incorporated. [000216] It should be added that the embodiments described are combinable provided they are not incompatible. Petition 870200161541, dated 12 / 28 / 2020, pages 60 / 63

Claims

1 / 6 CLAIMS 1. Optical marking device comprising at least a first layer (2) and a second layer (3) arranged at least partially opposite each other, at least one of said first and second layers comprising an optically variable element (4, 5) showing a color change between a first color and a second color, said first and second colors being in contrast with respect to a color of the other layer such that when the optically variable element (4, 5) shows said first color, the first layer (2) is visible and when the optically variable element (4, 5) shows said second color, the second layer (3) is visible or when the optically variable element (4, 5) shows said first color, the second layer (3) is visible and when the optically variable element (4, 5) shows said second color, the first layer (2) is visible, characterized in that the optically variable element (4,5) comprises one or more fluorescent compounds of the 4,4-difluoro-4-bora-3a,4a-diazas-indacene class and / or the β-diketonate difluoroboron (BF2bdks) class.

2. Device according to claim 1, characterized in that at least one of the two layers (2, 3) comprises a design (9, 10) provided with said optically variable element (4, 5).

3. Device, according to any of the preceding claims, characterized in that Petition 870250066157, dated 07 / 30 / 2025, page 13 / 24 2 / 6 comprises a substrate (11) bearing at least one of the aforementioned first and second layers.

4. Device, according to any of the preceding claims, characterized in that the two layers (2, 3) are in contact with each other.

5. Device, according to any of the preceding claims, characterized in that at least one of the two layers (2, 3) is at least partially reflective in the visible light spectrum and / or has shades of gray.

6. Device, according to any of the preceding claims, characterized in that at least one of the two layers (2, 3) is diffusing at least partially in the visible light spectrum.

7. Device, according to any of the preceding claims, characterized in that the compound or compounds of the class 4,4-difluoro-4-bora-3a, 4-adiazine-s-indacene are selected from those of formula I: wherein R1 is (C1-C6)alkyl, (C5-C6)cycloalkyl, (C5C6)heteroalkyl, phenyl, said phenyl group being optionally substituted with one or more groups selected from (C1-C2)alkyl, hydroxy, R5COO“ and halogen; R2 and R2' are independently selected from hydrogen and (C1-C2)alkyl;R3 and R3' are independently selected from hydrogen, aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, alkynyl, said aryl, heteroaryl, cycloalkyl, alkyl, alkenyl and alkynyl being optionally substituted with one or more groups selected from (C1-C4)alkyl, aryl, hydroxy and ferrocene, said aryl group being optionally substituted with one or more groups selected from aryl, (C1-C2)alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl being optionally substituted with a (C1-C2)alkyl group;R4 and R4' are independently selected from aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, said aryl, heteroaryl, cycloalkyl, alkyl and alkenyl being optionally substituted with one or more groups selected from (C1-C3)alkyl, aryl, hydroxy and ferrocene, said aryl group being optionally substituted with one or more groups selected from aryl, (C1-C2)alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl being optionally substituted with a (C1-C2)alkyl group; R5 is (C1-C4)alkyl or (C2-C4)alkenyl. R6 and R6' are independently selected from halogens, (C1-C4)alkoxy, (C2-C4)alkenyloxy, (C1-C4)alkyl, (C2-C4)alkenyl or aryl, the said aryl being optionally substituted with one or more groups selected from (C1-C2)alkyl, hydroxy, R5COO" and halogen.

8. Device, according to any of the preceding claims, characterized in that the compound or compounds of the β-diketonate (BF2bdks) class are selected from those of formula III: wherein L1 is an unsaturated aliphatic chain or is non-existent, L2 is an unsaturated aliphatic chain or is non-existent, R1 is a substituted or unsubstituted aryl group or is a substituted or unsubstituted heteroaryl group, R2 is a substituted or unsubstituted aryl group or is a substituted or unsubstituted heteroaryl group, and R3 is selected from hydrogen, a substituted or unsubstituted aryl group and a substituted or unsubstituted heteroaryl group.

9. Device, according to any of the preceding claims, characterized in that Petition 870250066157, dated 07 / 30 / 2025, p. 16 / 24 5 / 6 comprises a polymer incorporating the optically variable element (4, 5).

10. Device, according to any of the preceding claims, characterized in that the polymer is selected from polycarbonate, polystyrene, polyethylene, polypropylene, poly(ethylene terephthalate), polyacrylate, polymethacrylate, poly(vinyl chloride), polyamides, polyaramids, ethylene vinyl acetate (EVA), polyurethane, thermoplastic polyurethane (TPU), cyanoacrylate, rosins, pine resins, photopolymerizable resins or mixtures thereof.

11. Device, according to any of the preceding claims, characterized in that one of the aforementioned first and second colors of the layer comprising the optically variable element is the complementary color of the color of the other layer.

12. Device, according to any of the preceding claims, characterized in that the two layers (2, 3) comprise an optically variable element (4, 5) showing a color change, the two optically variable elements (4, 5) being at least partially overlapping and configured in such a way that only the first layer (2) is visible when a first stimulus is applied to the device (1) and that only the second layer is visible (3) when a second stimulus is applied to the device (1).

13. Device, according to any of the preceding claims, characterized in that it comprises an element configured to polarize the light that passes through said optical marking device (D - 14. Device, according to any of the preceding claims, characterized in that at least one of said first and second layers (2, 3) comprises a mixture of an optically variable element (4, 5) showing a color change between a first color and a second color, and a dye.

15. Device according to any of the preceding claims, characterized in that the dye is a fluorophore.

16. Identity, fiduciary or administrative document or label characterized in that it comprises at least one optical marking device (1) as defined in any of the preceding claims. Petition 870250066157, dated 07 / 30 / 2025, pp. 18 / 24

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