WO2019202278A1

WO2019202278A1 - Use of a fluorescent composition for securing a product

Info

Publication number: WO2019202278A1
Application number: PCT/FR2019/050939
Authority: WO
Inventors: Cosimo PRETE; Jérémy MALINGE; Alexis DEPAUW
Original assignee: Crime Science Technology
Priority date: 2018-04-19
Filing date: 2019-04-19
Publication date: 2019-10-24
Also published as: FR3080381A1; FR3080381B1

Abstract

The invention relates to the use of a fluorescent composition for securing a product, said composition comprising a polymer matrix incorporating a compound of the family of difluoroboron β-diketonates of formula (I) in which L¹ is an unsaturated or non-existant aliphatic chain, L² is an unsaturated or non-existant aliphatic chain, R¹ is a non-substituted or substitued aryl group or a non-substituted or substituted heteroaryl group, R² is a non-substituted or substituted aryl group or a non-substituted or substituted heteroaryl group and R³ is selected from hydrogen, an aryl group which is substituted or not, and a heteroaryl group which is substituted or not.

Description

USE OF A FLUORESCENT COMPOSITION FOR THE SAFETY OF

PRODUCT

Field of the invention

The present invention relates to the field of securing and authentication of products. More particularly, the invention relates to a fluorescent composition for securing and authenticating products such as identity, fiduciary and administrative documents.

Technical background

Counterfeiting and counterfeiting are developing significantly in many sectors such as packaging, including blister packaging of medicines, but also in high added value sectors such as luxury goods, automobiles and aeronautics. With the development of identity theft and the introduction of point licenses in some countries, identity and administrative documents are also being falsified. Securing and authentication of products is therefore essential and has both national and international security challenges.

Regarding product security such as an identity, fiduciary or administrative document, various companies provide visual authentication solutions, for example using holograms or laser engravings, which can be used to insert information about a product. body of plastic card such as an identity card, a health card or a driver's license.

Document EP0708935 A1 for example describes a set of holographic protection layers. This assembly consists of a support film having at least one layer formed by a protective varnish, a reflective or transparent layer carrying a diffracting microstructure, and finally, an adhesive layer. Once the set of layers transferred to a document we obtain the security of the latter. As described in WO2010 / 086522, this system was then improved through perforations to make it more difficult to separate the different layers. However, the set of layers, even perforated, consists of a multitude of parts that it is necessary to assemble which represents additional constraints in terms of time and cost.

Document FR 16 50164, of which the Applicant holds, discloses the use of a compound of the 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene family for the preparation of an element securing a product, in particular a document, said security element comprising a polymer and the compound being incorporated in said polymer. Although interesting, the use of the compounds described only makes it possible to obtain fluorescence emissions in the range from 500 nm to infra-red, and thus does not cover the entire range of the visible spectrum. Products, and especially documents, can be secured by security elements that can be classified according to three levels of security according to the means implemented for their detection. Thus, the level 1 security elements are elements that can be detected by at least one of the five senses or through a contrasting background. In this level will be found the guilloches, devices of optical variability such as iridescent prints, holograms, optically variable inks ("Optical Variable Ink"), markers, variable laser images ("Changeable Laser Image") or still multiple laser images ("Multiple Laser Image").

Level 2 security elements are detectable elements using simple equipment such as an Ultra-Violet lamp, a convex lens or a flash light from a mobile phone. This level includes detectable elements such as micro-prints, fluorescent inks, and fluorescent fibers or platelets.

Finally, the level 3 security elements are detectable elements using sophisticated equipment such as a spectrofluorometer or an electron microscope. In this category are particularly nano-engraved pigments, biometric chips and fluorescent markers not detectable to the naked eye (in English: taggants).

In general, a secure product incorporates several security elements of different levels.

Although the existing security solutions are interesting, some may be difficult to implement and / or control and the need to develop alternatives, especially in the visible spectrum, is still present.

There is therefore a real need to develop new security means simple to implement, stable, having fluorescence emissions and allowing rapid control of the authenticity of products. These new ways to ensure a high level of security and not to be exclusive of each other and already existing means.

It is therefore the merit of the inventors to have achieved all or part of these objectives by identifying and developing compounds that make it possible to obtain a fluorescent composition that is particularly advantageous for use in the field of product safety.

Summary of the invention

A first object of the invention relates to the use of a fluorescent composition for securing a product, said composition comprising a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate (BF2bdks) chosen from the compounds of formula I below:

in which,

L ¹ is an unsaturated or non-existent aliphatic chain,

L ² is an unsaturated or non-existent aliphatic chain,

R ¹ is an aryl or heteroaryl group, substituted or unsubstituted,

R ² is an aryl or heteroaryl group, substituted or unsubstituted, and

R ³ is chosen from hydrogen, a substituted or unsubstituted aryl group and a substituted or unsubstituted heteroaryl group.

A second object of the invention relates to a fluorescent security composition comprising a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate of formula I as above.

Finally, a third object of the invention relates to a method of securing a product comprising a step of preparing a fluorescent composition as defined above followed by a step of securing by applying said fluorescent composition prepared on at least one parts of said product.

Detailed description of the invention

The first compound of the difluoroborane b-diketonate family has been described by G. T. Morgan and R. B. Tundstall in 1924 (J. Chem Soc., 125 (1924) 1963-1964) and since then a multitude of compounds have been described and studied.

For example, the document P.-Z. Chen et al. Difluoroboron b-diketonate dyes: spectroscopic properties and applications, Coord. Chem. Rev. (2017) is a review describing methods of synthesis, photophysical properties and applications of certain compounds of the family of difluoroborane b-diketonate. This review mentions that these compounds exhibit exploitable fluorescent properties both in solution and in solid state, and find applications as a luminescent probe or optoelectronic device. As regards the use as a luminescent probe, this review also describes that these compounds covalently bound to polylactic acid (PLA) are used for the detection of oxygen and thus find an application for imaging or biological detection, but also in photo-dynamic therapies.

This review also reports on the use of compounds of the family of difluoroborane b-diketonate as a near-infrared probe (NIR probe) for the detection of aggregates of β-amyloid proteins, said aggregates being pathological markers of the disease. Alzheimer. Finally, the use of some of these compounds in applications such as photo-changeable molecular devices and optical memory storage systems is also reported.

Still relating to the applications of compounds of the family of difluoroborane b-diketonate, it is also known from WO2017 / 100764 a method and associated imaging systems for measuring the levels of oxygenation on a surface. More particularly, this document describes a method of monitoring healing by means of a double emission of a polylactic material b-diketonate naphthyl-phenyl difluoroborane.

Until now, compounds of the family of difluoroborane b-diketonate have been used for very specific applications in the fields of imaging, sensors or biodetection. It is therefore the merit of the inventors to propose a new way of using these compounds through product securing, said channel representing a field hitherto never explored or exploited by these molecules.

The use of the compounds according to the invention is particularly advantageous in that the compounds of the family of difluoroborane b-diketonate have a high quantum yield, that is to say between 0.5 and 1, and melting temperatures compatible with integration without degradation in a polymer matrix. However, the identification of new compounds for product safety was far from obvious in view of the plethoric number of fluorescent molecules present on the market, but also the qualitative requirements in terms of absorption and emission of fluorescences that 'imposes this particular area of security. Indeed, it is essential that the fluorescence emission of the selected compounds, even when integrated in polymer matrices, result in easily identifiable peaks on fluorescence emission spectra.

Similarly, the use according to the invention of compounds of the family of difluoroborane b-diketonate makes it possible to obtain fluorescent compositions having emission spectra in wavelengths lower than those developed at present in the field of product securing, especially via compounds of the 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene family. In addition, the inventors have found that the integration of these compounds in a semicrystalline polymer matrix tends to alter the perception of their fluorescent properties.

Without wishing to be bound by any theory, it seems that the semi-crystalline network of such a matrix interacting optically with said compounds thus somewhat disturbs the perception of fluorescence. Surprisingly, the perception of fluorescence is not impaired when the compounds of the family of difluoroborane b-diketonate according to the invention are incorporated in a semi-crystalline polymer matrix. Thus, the use according to the invention advantageously makes it possible to provide a means of product security that is more effective than the means already known.

A first object of the invention relates to the use of a fluorescent composition for securing a product, said composition comprising a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate (BF ₂ bdk) chosen from the compounds of formula I below:

in which,

L ¹ is an unsaturated or non-existent aliphatic chain,

L ² is an unsaturated or non-existent aliphatic chain,

R ¹ is an unsubstituted or substituted aryl group or an unsubstituted or substituted heteroaryl group,

R ² is an unsubstituted or substituted aryl group or an unsubstituted or substituted heteroaryl group, and

Preferred difluoroborane b-diketonate family compounds of formula I are those wherein one or more of L ¹ , L ² , R ¹ , R ² , and R ³ are defined as follows:

L ¹ is an unsaturated aliphatic chain, preferably C 2 to C 8 or non-existent,

L ² is an unsaturated aliphatic chain, preferably C 2 to C 8 or non-existent,

R 1 is an unsubstituted or substituted aryl group, preferably an unsubstituted or substituted aryl group with at least one electron donor or electron withdrawing group,

2 is an unsubstituted or substituted aryl group, preferably an aryl group unsubstituted or substituted by at least one electron donor or electron withdrawing group, and

3 is chosen from hydrogen and a substituted or unsubstituted aryl group. Preferred difluoroborane b-diketonate family compounds of formula I are those wherein one or more of L ¹ , L ² , R ¹ , R ² , and R ³ are defined as follows:

L ¹ is a C2 to C4 unsaturated aliphatic chain or nonexistent,

L ² is an unsaturated C 2 to C 4 aliphatic chain or nonexistent,

R is an aryl group unsubstituted or substituted by at least one group selected from hydroxy, alkoxy, alkyl, aryl, dialkylamino, thioalkoxy, halogen,

R ₂ is an aryl group unsubstituted or substituted by at least one group selected from hydroxy, alkoxy, alkyl, aryl, dialkylamino, thioalkoxy, halogen, and

R ₃ is selected from hydrogen and an unsubstituted aryl group.

L ¹ is a C2 to C4 unsaturated aliphatic chain or nonexistent,

L ² is an unsaturated C 2 to C 4 aliphatic chain or nonexistent,

R is an aryl group unsubstituted or substituted by at least one group selected from hydroxy, C1-C4 alkoxy, C1-C8 alkyl, aryl, C1-C4 dialkylamino, C1-C4 thioalkoxy, halogen, preferably fluorine,

R ₂ is an aryl group which is unsubstituted or substituted by at least one group selected from hydroxy, C 1 -C 4 alkoxy, C 1 -C 8 alkyl, aryl, C 1 -C 4 dialkylamino, C 1 -C 4 thioalkoxy, halogen, preferably fluorine , and

R ₃ is a hydrogen atom.

L ¹ is an unsaturated aliphatic chain C2 or nonexistent,

L ² is an unsaturated aliphatic chain C2 or non-existent,

R is an aryl group, preferably phenyl, biphenyl or naphthyl, unsubstituted or substituted by at least one group selected from hydroxy, C1-C4 alkoxy, preferably methoxy, C1-C8 alkyl, preferably t-butyl, aryl; C1-C4 alkylamino, preferably dimethylamino,

R ₂ is an aryl group, preferably phenyl, biphenyl or naphthyl, unsubstituted or substituted by at least one group selected from hydroxy, C1-C4 alkoxy, preferably methoxy, C1-C8 alkyl, preferably t-butyl, aryl, C1-C4 alkylamino, preferably dimethylamino, and R ₃ is a hydrogen atom.

Preferred compounds of the family of difluoroborane b-diketonate are those of formula I ₂ below:

Wherein R ¹ , R ² and R ³ are as defined in formula I.

Preferred compounds of the family of difluoroborane b-diketonate are those of formula I ₃ below:

In which L ¹ is an unsaturated aliphatic chain at C2 and R ¹ , R ² and R ³ are as defined in formula I.

Preferred compounds of the family of difluoroborane b-diketonate are those of formula I ₄ below:

In which L ² is an unsaturated C 2 and R ¹ aliphatic chain, R ² and R ³ are as defined in formula I.

In a particular embodiment, the compounds of the difluoroborane b-diketonate family of formula I, II, 12 are as defined above with the proviso that R 1 is not C 1 -C 4 alkoxy when R 2 is alkyl C1 to C8 and R1 is not C1 to C8 alkyl when R2 is C1-C4 alkoxy; the compounds of the family of difluoroborane b-diketonate of formula 13 are as defined above with the proviso that R 1 is not C 1 to C 8 alkyl when R 2 is C 1 -C 4 alkoxy and compounds of the B family are - difluoroborane diketonate of formula 14 are as defined above provided that R1 is not C1-C4 alkoxy when L2 and R2 is C1-C8 alkyl.

Particularly preferred compounds of the family of difluoroborane b-diketonate of formula I are as follows:

Compound 1 Compound 2

Compound 5 Compound 6

Compound 9 Compound 10

Compound 11 Compound 12

The term "alkyl" denotes a hydrocarbon radical of formula CnH2n + 1, linear or branched, in which n is an integer greater than or equal to 1. The preferred alkyl groups are linear or branched C1-C6 alkyl groups.

The term "alkenyl" denotes a linear or branched unsaturated alkyl group 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 more preferably still 2 or 3 carbon atoms. Non-limiting examples of alkenyl groups are ethenyl (vinyl), 2-propenyl (allyl), 2-butenyl and 3-butenyl, with ethenyl and 2-propenyl being preferred.

The term "cycloalkyl (e)", alone or as part of another group, refers to a saturated mono-, di- or tri-cyclic hydrocarbon radical having 3 to 12 carbon atoms, especially 5 to 10 carbon atoms. more particularly 6 to 10 carbon atoms. Suitable cycloalkyl radicals include, but are not limited to, cyclopentyl, cyclohexyl, norbomyl, adamantyl, especially cyclohexyl and adamantyl. Preferred cycloalkyl groups include cyclohexyl, adamant-1-yl and adamant-2-yl.

The term "aryl" refers to a polyunsaturated, aromatic, monocyclic (e.g., phenyl) or polycyclic hydrocarbon radical (e.g., naphthyl, anthracenyl, phenantracenyl, c). Preferred aryl groups include phenyl, naphthyl, anthracenyl, phenantracenyl, pyrenyl.

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

The term "halogen" refers to fluoro, chloro, bromo or iodo. Preferred halogen groups are fluoro and bromo, fluoro being particularly preferred.

The polymer matrix of the fluorescent composition according to the invention can be obtained from an amorphous or semi-crystalline polymer chosen from polycarbonate, polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polyacrylate, polymethacrylate, polyvinyl chloride, polyamides, polyaramids, vinyl ethylene acetate, polyurethane, thermoplastic polyurethane, cyanoacrylate, rosin resins, pine resins, photopolymerizable resins, acrylic and mixtures thereof. Preferably, the polymer matrix of the fluorescent composition can be obtained from a polymer chosen from polycarbonate, polyethylene, thermoplastic polyurethane, acrylic and photopolymerizable resins, and more preferably the polymer matrix is a matrix made of polycarbonate or polypropylene.

According to a particular embodiment, the polymer matrix is a semicrystalline polymer matrix.

Advantageously, the polymer matrix does not contain an anti-U.V additive so as to allow optimal maintenance of the fluorescence properties. Similarly, it is also advantageous to use a polymer matrix that retains its transparency properties even after a shaping step.

By the term "polymer matrix incorporating a compound of the family of difluoroborane b-diketonate" is meant within the meaning of the present invention that the compound of the family of difluoroborane b-diketonate is intimately integrated into the polymer matrix so to form a mixture. Preferably, the compound of the family of difluoroborane b-diketonate is intimately integrated into the polymer matrix so as to form a homogeneous mixture having no dispersion. The integration of the compound into the polymer matrix may for example be carried out hot. In this case, the polymer matrix is heated to its melting temperature, and then the compound of formula I is added to the melt before the assembly is mixed.

In a particularly advantageous manner, the inventors have found that the compounds of formula I according to the invention could be incorporated in polymer matrices without altering either the performance of the matrix, or especially those of the incorporated compounds.

In the present description, conventionally the indefinite article "a" must be considered as a generic plural (meaning "at least one" or "one or more"), except when the context shows the opposite (1 or "only one"). "). For example, when it is mentioned above that the polymer matrix incorporates a compound of the family of difluoroborane b-diketonate, it should be understood that the polymer matrix incorporates one or more compounds of the b-diketonate family. difluoroborane. Within the fluorescent composition according to the invention, the polymer matrix incorporates an amount of compound of the family of difluoroborane b-diketonate necessary for the detection of the absorbance and fluorescence properties. The compounds of formula I according to the invention have the advantage of enabling detection of said properties, even when they are incorporated in small quantities within the polymer matrix. Thus, the amounts of compounds of formula I ranging from 0.01% to 5% by weight relative to the total weight of the polymer matrix are sufficient for the detection, preferably amounts ranging from 0.01% to 2% by weight per relative to the total weight of the polymer matrix and even more preferably, amounts ranging from 0.01% to 1% by weight relative to the total weight of the polymer matrix.

The fluorescent composition according to the invention is therefore used for securing a product. Lin produced in the sense of the present invention may be any type of product capable of receiving said fluorescent composition. The product can thus be a solid or a liquid. It may for example be plastic objects such as parts or packaging, luxury products such as leather goods, cosmetics, paints or documents. Preferably, the products are documents.

The term document refers in particular to a set formed by a support and information. The support may be of different natures, take different forms, and may optionally comprise a polymer or a mixture of polymers. This support may for example consist entirely or partly of a polymeric material. 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 such as registration certificates. The documents can be in the form of paper, booklet or card and information can be printed and / or engraved.

For the purposes of the present invention, the expression "securing a product" is intended to mean that the fluorescent composition is integrated on the product or in the product to be secured at any time during its design. Thus, the fluorescent composition can be used as well for securing the product during its manufacture, as it may be applied or subsequently integrated into the latter. For example, in the context of securing a document type product, the fluorescent composition can be applied retrospectively on all or part of the document. This point is developed further in the description.

In all cases, the products are secured by the use of a fluorescent composition comprising a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate described above and may be authenticated through the properties and effects conferred by the composition. fluorescent. Indeed, the secure products according to the invention can be authenticated by virtue of the unique combination of the absorbed color and the specific fluorescence of the fluorescent composition. Thus, only an authentic product will have both good absorption and fluorescence emission properties. Authentication in the sense of the present invention is understood as the verification of the authenticity of a product by the detection of the fluorescent composition or the security means incorporated therein. This detection of the presence or absence of coloration or fluorescence thus makes it possible to authenticate or not the product in question. A product is therefore authentic when a detection reveals the presence of the fluorescent composition, as opposed to a non-authentic product for which the detection will not make it possible to highlight the fluorescent composition. The secure products according to the invention via a fluorescent composition can be authenticated on the three levels of security described above by the mere presence of said fluorescent composition.

Indeed, the compounds of formula I contained in the fluorescent composition may have a band of absorption in the visible and the color perceived with the naked eye will correspond to the complementary color of the absorbed color. For example, an absorbent compound at 500-520 nm, which corresponds to a green / blue color, will appear to the naked eye in orange / red tones. This property thus makes it possible to obtain a level 1 security.

As regards the fluorescence properties, the compounds of formula I according to the invention all have excitation bands in the Ultra-Violet (U.V.). They can therefore be excited, in particular by means of a UV or T EP lamp emitting between 100 nm and 400 nm, which makes it possible to obtain a level 2 security. This property makes it possible to obtain an activation / deactivation effect. / off) which therefore corresponds to the visualization of a color change following stimulation of the fluorescence of the fluorescent composition, in particular by a LED or UV light source.

Finally, the emission wavelength can be determined using a spectrofluorometer or low-resolution single-grating fluorimeter (detection by photodiode or photomultiplier tube), which confers on the security elements according to the present invention a level 3 of security.

Thus, the products and in particular the secure documents according to the present invention will be, thanks to the combination of the absorption and fluorescence properties, detectable on the 3 levels of security.

The fluorescent composition according to the present invention may be in several forms that are adapted by the skilled person depending on the product to be secured. For example, if the product is a document, the fluorescent composition may be in the form of a layer, a layer assembly or a film.

According to a particular embodiment, the fluorescent composition is used in the form of a layer or a set of layers prepared by techniques known to those skilled in the art, for example rolling, extrusion, calendering, or extmsion calendering. These techniques will be chosen according to the polymer matrix used. For example, if the matrix is polycarbonate or thermoplastic polyurethane, calendering extrusion shaping is preferred. By way of example again, if the matrix is made of polypropylene, the principle of inflation extrusion is preferred, in particular the principle of inflation extrusion with bi-stretching. A set of layers in the sense of the present invention may for example be obtained by rolling two or more polymer matrix layers each incorporating one or more fluorescent compositions. Such a layer or set of layers finds a particularly advantageous application in securing documents, and more particularly identity, fiduciary or administrative documents. According to this particular embodiment, the layer or set of layers is in the form of a card. Examples of cards include business cards, bank cards, or any other type of polymer matrix card. In this case, the fluorescent composition according to the invention constitutes the support of the document as such. The cards may for example be obtained by rolling several polymer layers, at least one of which is the fluorescent composition according to the present invention.

In a particularly advantageous manner, the layer or set of layers is transparent, which makes it possible to obtain, in addition to the effects described above, the following effects:

waveguide effect: the presence of grooves in the layer or set of layers generates a different diffraction index which stimulates the fluorescence of the secure layer. Thus, the color observed at the groove is different from that observed on the remainder of the layer or set of layers. This is a level 1 security.

color change effect (switch-color): this effect corresponds to a change of color during the superposition of the layer or set of layers on a contrasting background (dark background type, especially black, or light background, especially white The complementary color of the color absorbed on a light background and the color of fluorescence on a dark background are thus observed, which constitutes a level 1 security.

side-effect: this effect corresponds to the observation of a complementary color of the absorbed color which is different on the slices of the layer or set of layers, from that observed on the faces. This is a level 1 security.

shadow effect: this effect corresponds, when one stimulates the fluorescence by a light type 1 II) or UV and that one observes on a light background, in particular white, with the visualization of both the color of fluorescence at the level of the layer and the projection of the color complementary to the color absorbed on the light background. This is a level 2 security.

Advantageously, a layer has in particular a thickness ranging from 0.050 mm to 0.800 mm, preferably a thickness ranging from 0.200 mm to 0.600 mm, such as for example a thickness of about 0.400 mm. When the layer has a thickness less than 0.100 mm, it is also called film. According to a particular embodiment, the fluorescent composition comprises only a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate as defined above.

According to another particular embodiment, the fluorescent composition consists essentially of a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate as defined above. For the purposes of the present invention, the expression "essentially constituted" is intended to mean that the fluorescent composition consists of more than 96%, 97%, 98% or even more than 99% of an integral polymer matrix. a compound of the family of difluoroborane b-diketonate of formula I.

According to a particular embodiment, the fluorescent composition is in the form of a fluorescent ink. According to this embodiment, the fluorescent ink is an ink suitable for printing, especially for screen printing, offset printing and inkjet printing. Surprisingly, the inventors have advantageously found that the fluorescent inks according to the invention could be used in printing without causing a clogging of the printing heads.

According to another particular embodiment, the fluorescent composition is in the form of a fluorescent varnish.

According to one particular embodiment, the fluorescent composition is used in the form of a film, a layer that is to say a layer having a thickness of less than 0.100 mm, in particular ranging from 0.050 mm to 0.100 mm, which is used to laminate both sides of a document, including an identity, fiduciary or administrative document. In a variant of this embodiment, such a film is applied to only one of the two faces of a document, in particular an identity document. In yet another variant of the embodiment, such a film is applied to only part of one of the two faces of a document, including an identity document. In yet another variant of the embodiment, such a film is applied to only a portion of each of the two faces of a document, including an identity document.

According to another particular embodiment, the fluorescent composition is in the form of a fiber. This shaping can be done by the techniques conventionally used for obtaining the fibers, said fibers being able to be either woven fibers or nonwoven fibers.

According to this embodiment, the fibers are preferably obtained by the technique of melt spinning, via an extrusion-spinning process. The manufacture of fibers by the melt spinning method first consists in melting the mixture of polymer and fluorescent compound in an extruder. The melt is then sent under pressure through a die consisting of a multitude of heads. On leaving the die, the filaments are cooled by air, stretched and then wound on a support. Generally, a sizing product can be applied to the lower part of the spinning chimney. The shape of the fluorescent fiber obtained by the extrusion-spinning processes may in particular be determined by the shape of the heads of the die. Thus, the fiber may in particular have a cylindrical shape, trilobal, octalobed, hollow or multiple hollow. The modification of the shape of the fibers may be advantageous in that it makes it possible to modify the visual effects on the macroscopic scale. Indeed, the discontinuity of a section or refractive index of light within the fiber can modify the transmission of light and therefore the effects observed at the macroscopic scale.

According to another particular embodiment, several fluorescent compositions are used to secure the same product, the fluorescent compositions being different from each other at least by the nature of the compound of formula I embedded in the polymer matrix. This embodiment advantageously makes it possible to better secure the product in question.

According to another particular embodiment, the polymer matrix is a photopolymerizable resin and the fluorescent composition also comprises a polar solvent to facilitate the integration between the resin and the compound of formula I. The fluorescent composition obtained thus finds a very particular application in some 3D printing techniques, for example for the manufacture of holograms, said holograms then having a higher level of security.

According to a particular embodiment of the invention, the fluorescent composition also comprises a compound of the family of 4-bora-3a, 4a-diaza-s-indacene, also called "BODIPY", said BODIPY being incorporated into the polymer matrix . In particular, according to this embodiment, the BODIPYs may be compounds of formula II below:

in which,

R ¹ is C ¹ -C ⁶ alkyl, C 5 -C 6 cycloalkyl, C 5 -C 6 heteroalkyl, phenyl, said phenyl group being optionally substituted with one or more groups selected from C 1 -C 2 alkyl, hydroxy, R ^s COO and halogen;

R ² and R ² 'are independently selected from hydrogen and C 1 -C 2 alkyl; R ³ and R ^{3 '} are independently selected from hydrogen, aryl, heteroaryl, cycloalkyl, alkyl, alkenyl, alkynyl, said aryl, heteroaryl, cycloalkyl, alkyl, alkenyl and alkynyl being optionally substituted by one or more groups selected from alkyl C1 to C4, aryl, hydroxy and ferrocene, said aryl group being optionally substituted by one or more groups selected from aryl, C1 to C2 alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl being optionally substituted by a C1 to C2 alkyl group;

R ⁴ and R ⁴ 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 C 1 to C 3 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, nitro, said aryl being optionally substituted by a C1-C2 alkyl group;

R ⁵ is C 1 -C ⁴ alkyl or C 2 -C 4 alkenyl.

R ⁶ and R ^{6 '} are independently selected from halogen, C 1 -C 4 alkoxy, C 2 -C 4 alkenyloxy, C 1 -C 4 alkyl, C 2 -C 4 alkenyl or aryl, said aryl being optionally substituted with one or more selected groups ( s) from C1 to C2 alkyl, hydroxy, R ^s COO- and halogen.

Preferred compounds of formula I are those in which one or more of R, R, R, R, R, R,

R ⁴ , R ⁵ , R ⁶ and R ⁶ are defined as follows:

R ¹ is phenyl substituted with one or more groups selected from methyl, fluoro, hydroxy, acetyl and methacrylate, preferably from methyl, fluoro, hydroxy and acetyl and more preferably from methyl or fluoro;

R ² and R ^{2 '} are independently selected from hydrogen and methyl;

R ³ and R ^{3 '} are independently selected from hydrogen, C 1 -C 3 alkyl, vinyl, aryl, heteroaryl, adamantyl, said vinyl and aryl being optionally substituted by one or more groups selected from phenyl, C 1 -C 2 alkyl said phenyl being optionally substituted with one or more groups selected from C1 to C2 alkyl, hydroxy, bromo, nitro, dimethylamine, preferably hydrogen, methyl, ethyl, n-propyl, vinyl, aryl, heteroaryl, adamantyl, said vinyl and aryl being optionally substituted with one or more groups selected from phenyl, C1-C₂ alkyl, said phenyl being optionally substituted by one or more groups selected from C1-C₂ alkyl, hydroxy, bromo, nitro, dimethylamine, more preferably, R ³ and R ³ are independently selected from ethyl, n-propyl, methyl, vinyl, phenyl, phenantryl, naphthyl, pyrenyl, thiophenyl, benzofuranyl, said vinyl, aryl and naphthyl being optionally substituted with one or more methyl, hydroxy, bromo, nitro and dimethylamino;

R ⁴ and R ⁴ 'are independently selected from methyl, vinyl, aryl, heteroaryl, adamanthyl, said vinyl and aryl being optionally substituted by one or more groups selected from phenyl, C1 to C2 alkyl, said phenyl being optionally substituted; by one or more groups selected from C1 to C2 alkyl, hydroxy, bromo, nitro, dimethylamine,

preferably R ⁴ and R ⁴ are independently selected from methyl, vinyl, phenyl, phenantryl, naphthyl, pyrenyl, thiophenyl, benzofuranyl, said vinyl, aryl and naphthyl being optionally substituted with one or more methyl, hydroxy, bromo, nitro and dimethylamino;

R ⁵ is methyl or ethenyl.

R ⁶ and R ⁶ 'are independently selected from fluoro, C 1 -C 4 alkoxy, C 2 -C 4 alkenyloxy, C 1 -C 4 alkyl, C 2 -C 4 alkenyl or aryl, said aryl being optionally substituted with one or more selected groups ( s) from alkyl Cl to C2, hydroxy, R ^s COO- and halogen, preferably R ⁶ and R ⁶ are fluoro.

According to this embodiment, the amounts of compounds of formula II are from 0.01% to 5% by weight relative to the total weight of the polymer matrix, preferably amounts ranging from 0.01% to 2% by weight relative to to the total weight of the polymer matrix and even more preferably, amounts ranging from 0.01% to 1% by weight relative to the total weight of the polymer matrix.

According to a variant of this particular embodiment, the fluorescent composition comprises only a polymer matrix incorporating a compound of the difluoroborane b-diketonate family as defined above and a compound of the 4,4-difluoro-4-bora family. -3a, 4a-diaza-s-indacene of formula II as defined above.

According to another particular embodiment, the fluorescent composition also comprises a compound of the 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene family, also called "BODIPY", said BODIPY also being incorporated in the polymer matrix. In particular, according to this embodiment, the BODIPY can be compounds of formula III below:

in which,

R ² and R ^{2 '} are independently selected from hydrogen and C 1 -C 2 alkyl;

R ³ and R ³ are independently selected from hydrogen and C 1 -C 3 alkyl;

R ⁵ is C 1 -C ⁴ alkyl or C 2 -C 4 alkenyl.

Preferred BODIPYs of formula III are those in which one or more of R ¹ , R ² , R ² , R ³ , R ³ ,

R ⁴ , R ^{4 '} and R ⁵ are defined as follows:

R ² and R ^{2 '} are independently selected from hydrogen and methyl;

R ³ and R ^{3 '} are independently selected from hydrogen, methyl, ethyl, n-propyl and preferably ethyl;

R ⁴ and R ^{4 '} are independently selected from methyl, vinyl, aryl, heteroaryl, adamanthyl, said vinyl and aryl being optionally substituted by one or more groups selected from phenyl, C1 to C2 alkyl, said phenyl being optionally substituted; by one or more groups selected from C1 to C2 alkyl, hydroxy, bromo, nitro, dimethylamine, preferably R ⁴ and R ⁴ are independently selected from methyl, vinyl, phenyl, phenanthracenyl, naphthalenyl, pyrenyl, thiphenyl, benzofuranyl, said vinyl, aryl and naphthalenyl being optionally substituted by one or more methyl, hydrocyclo, bromo, nitro and dimethylamino;

R ⁵ is methyl or ethenyl.

According to this embodiment, the amounts of compounds of formula III are from 0.01% to 5% by weight relative to the total weight of the polymer matrix, preferably amounts ranging from 0.01% to 2% by weight relative to to the total weight of the polymer matrix and even more preferably, amounts ranging from 0.01% to 1% by weight relative to the total weight of the polymer matrix.

According to a variant of this particular embodiment, the fluorescent composition comprises only a polymer matrix incorporating a compound of the difluoroborane b-diketonate family as defined above and a compound of the 4,4-difluoro-4-bora family. -3a, 4a-diaza-s-indacene of formula III as defined above.

According to a particular embodiment, the fluorescent composition also comprises a difractant network or a reasoning network.

The fluorescent composition according to the invention comprising a polymer matrix in which are incorporated a compound of the family of difluoroborane b-diketonate and a BODIPY compound as defined above makes it possible to obtain fluorescent compositions with particularly advantageous properties. .

Indeed, when a compound of each family is mixed together and said compounds emit at different wavelengths, it is then possible to modify the fluorescence color emitted under UV. However, and advantageously, the properties of detection of the fluorescent composition according to level 1 and level 2 by flash light of a mobile phone remain unchanged and are not altered.

The fluorescent composition thus obtained has two colors, a first which is visible for example on a black background and under flash light of a mobile phone, and the second under irradiation U.V.

Another advantage of having a fluorescent composition comprising a polymer matrix in which is incorporated a compound of the family of difluoroborane b-diketonate and a BODIPY compound is that under UV irradiation, a white fluorescence can be obtained depending on the selected compounds .

A second object of the invention relates to a fluorescent security composition comprising a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate of formula I as above. The polymer matrix of the fluorescent composition can be obtained from an amorphous or semi-crystalline polymer chosen from polycarbonate, polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polyacrylate, polymethacrylate, poly (chloride vinyl), polyamides, polyaramids, vinyl ethylene acetate, polyurethane, thermoplastic polyurethane, cyanoacrilate, rosin resins, pine resins, photopolymerizable resins, acrylic and mixtures thereof.

Preferably, the polymer matrix of the fluorescent composition can be obtained from a polymer chosen from polycarbonate, polypropylene, thermoplastic polyurethane, acrylic and photopolymerizable resins, and more preferably, the polymer matrix is a polycarbonate or polypropylene matrix.

The third subject of the invention relates to a method of securing a product comprising the following steps of:

preparation of a fluorescent composition as defined above,

securing by applying said fluorescent composition prepared in the preceding step, on at least one of the parts of said product.

The first step therefore consists in obtaining a fluorescent composition as defined above.

According to a particular embodiment, the first step of the security method consists in preparing a fluorescent composition comprising only a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate of formula I as defined above.

According to another particular embodiment, the first step of the security method consists in preparing a fluorescent composition consisting essentially of a polymer matrix incorporating a compound of the difluoroborane b-diketonate family as defined above. For the purposes of the present invention, the expression "essentially constituted" is intended to mean that the fluorescent composition consists of more than 96%, 97%, 98% or even more than 99% of an integral polymer matrix. a compound of the family of difluoroborane b-diketonate of formula I.

According to a particular embodiment, the first step of the security method consists in preparing a fluorescent composition comprising only a polymer matrix incorporating a compound of the difluoroborane b-diketonate family as defined above and a compound of the family of 4, 4-difluoro-4-bora-3a, 4a-diaza-s-indacene of formula II or III as defined above.

According to a particular embodiment, the fluorescent composition is a fluorescent ink. According to this embodiment, the fluorescent ink is obtained from an ink known to those skilled in the art, said inks comprising a polymer matrix, in which is incorporated a compound of the family of difluoroborane b-diketonate so to obtain the fluorescent ink. According to this embodiment, the security step is advantageously performed by printing the fluorescent ink on the product to be secured, such as a document.

According to a particular embodiment, the fluorescent composition is a fluorescent varnish. According to this embodiment, the security step may for example be performed by coating or varnishing said fluorescent varnish on the product to be secured.

The step of securing all or part of the product to be secured is adapted by the skilled person depending on the product to be secured but also the shape of said composition.

The security step consists in integrating the fluorescent composition into the product to be secured. Thus, the security step may as well be performed during the manufacture of the product, that it is performed a posteriori to the latter. For example, in the context of securing a document type product, the security step can be performed on the finished product. In addition, this step can be repeated several times on the same product to increase the level of product security.

The security step can be performed according to the techniques known to those skilled in the art such as by rolling, printing, weaving, varnishing, lacquering or by gluing.

According to a particular embodiment, the fluorescent composition according to the invention is applied by coating on a reflective surface or a metallized surface. The product is then secured by application of the assembly consisting of the reflective or metallized layer coated with the fluorescent composition. The metallized surfaces are layers known to those skilled in the art, it may be for example aluminum metal layer.

Advantageously, according to this embodiment, the fluorescent properties of the fluorescent composition interact with the reflective aspect of the reflective layer and this makes it possible to obtain specific visual effects for securing a product.

The security method according to the invention may also comprise a step of shaping the fluorescent composition before the security step. The shaping step can be carried out according to the techniques known to those skilled in the art which allow for example to obtain a layer, a set of layers, a film or fibers. This formatting step can thus facilitate the subsequent step of securing by application.

According to a particular embodiment, the first step of the process consists of preparing several fluorescent compositions which differ in the nature of the compound of the family of difluoroborane b-diketonate of formula I incorporated in the polymer matrix. According to this embodiment, the security step consists of applying simultaneously or deferred compositions prepared and thus increase the level of security conferred on the product. The method according to the invention can be used to secure any type of product capable of receiving said fluorescent composition. It may for example be plastic objects such as parts or packaging, luxury goods such as leather goods, or documents. Preferably, the products secured according to the method described are documents.

According to a particular embodiment, the product to be secured is a document such as an identity, fiduciary or administrative document. According to this embodiment, the application of the fluorescent security composition may be carried out on at least a portion of a face of the product. According to a variant of this embodiment, the fluorescent security composition is in the form of a film before being hot or cold rolled on all the faces of the document. In another variant, the film is applied to only one of the faces of a document. In yet another variant, the film is applied to only a part of one of the two faces of a document and in another variant, the film is applied to only part of each of the faces. of a document.

According to another particular embodiment, the polymer matrix of the fluorescent composition also incorporates a compound of the 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene family such as the compounds of formula (II) ) previously defined.

The invention will be better understood with the aid of the following figures and examples, which are intended to be illustrative and not limiting.

FIG. 1: UV-visible spectrum (broken line) and fluorescence emission spectrum (solid line, Lexc = 403 nm) recorded in dichloromethane of a compound A of the difluoroborane b-diketonate family.

Figure 2: UV-visible spectrum (dashed line) and fluorescence emission spectrum (solid line, .cxc = 403 nm) recorded in dichloromethane of a compound B of the family of difluoroborane b-diketonate.

Example 1 Preparation of a fluorescent composition in the form of a layer and its use for securing

For this example, the compound of the family of difluoroborane b-diketonate used is the compound A of formula below:

Compound A

6- (4- (tert-butyl) phenyl) -2,2-difluoro-4- (4-methoxyphenyl) -2H-3,2-dioxaborinin-l-ium-2-fluid.

This compound A is in the form of a yellow powder and absorbs at 403 nm and has a fluorescence emission at 433 nm. 17 grams of compound are mixed with 10 kg of polycarbonate (PC Makralon 2456) through an extmeuse so as to obtain the fluorescent composition.

The extrusion is carried out on a twin-screw extruder (Brabender) with a screw rotation speed of 50 rpm, a hopper flow rate of 3.8 kg / h and the following temperature profile: 275 ° C -280 ° C -280 ° C - 285 ° C -285 ° C -285 ° C -290 ° C (supply => filial).

From the extruded fluorescent composition, a quantity is taken and then diluted 10 times by adding polycarbonate (Makralon PC 2456) through a Fairex extruder (diameter 45) equipped with Scamex flat dies with a width of 350 mm, followed by a 3-cylinder calender with a 30 ° inclination.

At the outlet of the calender, the fluorescent composition is then in the form of a layer with a thickness of 100 mm. After adjusting the calender, the test was repeated to obtain a second layer 400 mm thick from the fluorescent composition.

The secured layers thus obtained are then used as document support, said document being thus secured.

The visual and spectrophotometric analyzes of the layers obtained show that the incorporation of the fluorescent dye into the polycarbonate does not alter its performance in terms of absorption and fluorescence emission. The fluorescent layers obtained have properties similar to those observed when the compound is in solution.

Example 2 Preparation of a Fluorescent Composition in the Form of Varnish and Its Use for Securing.

The same compound as Example 1 is used. 44 mg of compound A are embedded in 10 g of solvent-based acrylic varnish (0.4% w / w). The fluorescent varnish thus obtained is then coated on a 100 μm thick polyethylene terephthalate film using an automatic applicator (TQC ASTM D 823) and a 20 μm Meyer bar with an application speed of 50 μm. mm / s.

The measured deposit of varnish has a thickness of 5 μm in agreement with a solvent-based varnish with 33% solids.

The assembly consisting of the polyethylene terephthalate film coated with the fluorescent varnish forms a fluorescent layer. The fluorescent layer thus obtained is a secure layer. When illuminated with a U.V lamp (385 nm), a blue fluorescence appears with the naked eye.

Visual and spectrophotometric analysis of the secure layer shows that incorporation of the fluorescent dye into the polycarbonate does not alter its performance in terms of absorption and fluorescence emission.

The secured layer thus obtained, through its fluorescence properties, is used as a support for a card.

Example 3 Preparation of a Fluorescent Composition in the Form of Varnish and its Use for Coating a Metallized Layer for Securing

For this example, the compound of the family of difluoroborane b-diketonate used is the compound B of formula below:

Compound B

4,6-bis (4- (dimethylamino) phenyl) -2,2-difluoro-2H-3,2-dioxaborinin-l-ium-2-fluid

This compound absorbs at 403 nm and has a fluorescence emission at 512 nm. 80 mg of compound are integrated in 10 g of solvent-based acrylic lacquer so as to obtain a fluorescent green varnish (0.8% w / w).

The fluorescent varnish thus obtained is then coated on a metallized polyethylene terephthalate film 100 μm thick using an automatic applicator (automatic film applicator, TQC ASTM D 823) and a 40 μm Meyer bar with a speed of application of 50 mm / s. The measured deposit of varnish has a thickness of 12 .mu.m in agreement with a varnish based on solvent at 33% solids content. The assembly consisting of the metallized polyethylene terephthalate film coated with a layer of fluorescent varnish forms a fluorescent layer.

The fluorescent layer thus obtained is secured and is then used as a document medium.

The fluorescent layer has properties similar to those observed when the compound is in solution. Beyond a green fluorescence observable under UV light (365 nm), the green emission (emission = 512 nm) can be observed by slightly tilting (about 30 °) the fluorescent layer.

Indeed, the reflective surface disposed beneath the layer makes it possible to obtain effects on the perception of fluorescence and to obtain combined properties for securing a product.

This example demonstrates the application and maintenance of the fluorescence properties of a fluorescent composition in the form of a varnish according to the invention by coating on a reflecting surface.

Example 4: Preparation of a fluorescent ink composition comprising a compound of the family of difluoroborane b-diketonate (BF2bdks) and a compound of the family 4,4-difluoro-4-bora-3a, 4a diaza-s-indacene according to the invention.

For this example, the compound of the family of difluoroborane b-diketonate used is the compound C of formula below:

Compound C

4 - ([l, r-biphenyl] -4-yl) -2,2-difluoro-6- (4-dimethylaminophenyl) -l, 3,2-dioxaborinine

This compound C is in the form of a yellow powder, absorbs at 402 nm, has a fluorescence emission at 445 nm and a fluorance quantum yield f _R = 0.52.

The compound of the 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene family used is the compound D of formula below:

Compound D

5,5-difluoro-1,3,7,9-tetramethyl-10-phenyl-5H-dipyrrolo [1,2-c: 2 ', 1' - [1, 3,2] diazaborinin-4 ium-5uide

This compound D is in the form of a green powder, absorbs at 502 nm, has a fluorescence emission at 512 nm and a fluorescence quantum yield cp _F = 1.

Preparation of the fluorescent composition in ink form:

400 mg of compound C are uniformly dissolved in 100 g of transparent Mara® Gloss GO transparent virgin screen printing ink dispensed by Marabu Company compatible with a polycarbonate plastic surface printing.

100 mg of the compound D are uniformly dissolved in 100 g of the same transparent virgin screen printing ink.

The ink containing the compound C and the ink containing the compound D are then mixed in a ratio 1: 1 by weight.

The fluorescent composition thus formulated is printed on a transparent polycarbonate card.

Results: The fluorescent composition ran perfectly through the printheads which were not obstructed.

The pattern thus printed has a yellow color visible by transparency when said card is arranged on a white background, and a green color visible by transparency when said card is arranged on a black background.

When the map is illuminated under U.V, a white fluorescence is visible. This white fluorescence is particularly interesting because it is obtained here with only two fluorescent compounds.

Claims

1. Use of a fluorescent composition for securing a product, said composition comprising a polymer matrix incorporating a compound of the family of difluoroborane b-diketonate (BF2bdks) chosen from the compounds of formula I below:

in which,

L ¹ is an unsaturated or non-existent aliphatic chain,

L ² is an unsaturated or non-existent aliphatic chain,

2. Use of a fluorescent composition according to claim 1, characterized in that the polymer of the matrix is selected from polycarbonate, polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polyacrylate, polymethacrylate, poly (chloride vinyl), polyamides, polyaramids, vinyl ethylene acetate (EVA), polyurethane, thermoplastic polyurethane (TPU), cyanoacrilate, rosin resins, pine resins, photopolymerizable resins or mixtures thereof.

3. Use of a fluorescent composition according to one of claims 1 or 2, characterized in that the fluorescent composition also comprises a compound of the 4,4-difluoro-4-bora-3a, 4a-diaza-s family. -indacenes of formula II below:

in which,

R ² and R ^{2 '} are independently selected from hydrogen and C 1 -C 2 alkyl;

R ³ and R ³ 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 to C4, aryl, hydroxy and ferrocene, said aryl group being optionally substituted by one or more groups selected from aryl, C1 to C2 alkyl, halogen, hydroxy, dimethylamino, nitro, said aryl being optionally substituted by a grouping C1 to C2 alkyl;

R ⁵ is C 1 -C ⁴ alkyl or C 2 -C 4 alkenyl.

4. Use of a fluorescent composition according to one of claims 1 to 3, characterized in that the product to be secured is a document.

A fluorescent security composition comprising a polymer matrix incorporating a compound of the difluoroborane b-diketonate family of formula I below:

in which,

L ¹ is an unsaturated or non-existent aliphatic chain,

L ² is an unsaturated or non-existent aliphatic chain,

6. Fluorescent security composition according to claim 5, characterized in that the polymer is chosen from polycarbonate, polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polyacrylate, polymethacrylate, polyvinyl chloride, polyamides, polyaramids, vinyl ethylene acetate (EVA), polyurethane, thermoplastic polyurethane (TPU), or cyanoacrilate, rosin resins, pine resins, acrylic, photopolymerizable resins or mixtures thereof.

7. fluorescent security composition according to one of claims 5 or 6, characterized in that it also comprises a compound of the family of 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacènes de formula II below:

in which,

R ² and R ² 'are independently selected from hydrogen and C 1 -C 2 alkyl;

R ⁵ is C 1 -C ⁴ alkyl or C 2 -C 4 alkenyl.

R ⁶ and R ⁶ 'are independently selected from halogen, C 1 -C 4 alkoxy, C 2 -C 4 alkenyloxy, C 1 -C 4 alkyl, C 2 -C 4 alkenyl or aryl, said aryl being optionally substituted with one or more selected groups ( s) from C1 to C2 alkyl, hydroxy, R ^s COO- and halogen.

8. A method of securing a product comprising a step of preparing a fluorescent security composition as defined in one of claims 5 to 7 and a step of securing by applying said fluorescent composition to at least a portion of the product to be secured.

9. A method of securing a product according to claim 8, characterized in that the securing step is performed by rolling, printing, weaving, or gluing.

10. A method of securing a product according to one of claims 8 or 9, characterized in that it comprises a shaping step of the fluorescent composition before the securing step.

11. Method for securing a product according to claim 8, characterized in that the fluorescent composition is a fluorescent ink and in that the security step is performed by printing.

12. Securing method according to one of claims 8 to 11, characterized in that the product is an identity document, fiduciary or administrative.