EP2986687A1 - Luminescent inorganic core/shell particle, production method and use - Google Patents

Luminescent inorganic core/shell particle, production method and use

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Publication number
EP2986687A1
EP2986687A1 EP14720643.7A EP14720643A EP2986687A1 EP 2986687 A1 EP2986687 A1 EP 2986687A1 EP 14720643 A EP14720643 A EP 14720643A EP 2986687 A1 EP2986687 A1 EP 2986687A1
Authority
EP
European Patent Office
Prior art keywords
shell
core
particles
luminescent
particle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14720643.7A
Other languages
German (de)
French (fr)
Inventor
Nicolas Charvet
Philippe Capron
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Commissariat a lEnergie Atomique et aux Energies Alternatives CEA filed Critical Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Publication of EP2986687A1 publication Critical patent/EP2986687A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02—Making microcapsules or microballoons
    • B01J13/20—After-treatment of capsule walls, e.g. hardening
    • B01J13/206—Hardening; drying
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02—Making microcapsules or microballoons
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/02—Printing inks
    • C09D11/10—Printing inks based on artificial resins
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/50—Sympathetic, colour changing or similar inks
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
    • C09K11/025—Use of particular materials as binders, particle coatings or suspension media therefor non-luminescent particle coatings or suspension media
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
    • B41M3/14—Security printing
    • B41M3/144—Security printing using fluorescent, luminescent or iridescent effects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B42D25/378—Special inks

Definitions

  • the invention relates to an inorganic core / shell particle having luminescence properties emanating from the presence of at least one element selected from rare earths.
  • the field of use of the present invention relates in particular to the use of these luminescent particles for marking objects in the context of the fight against counterfeiting.
  • Luminescence corresponds to the emission of light in a fast manner (fluorescence) or slower (phosphorescence) following the absorption of photons by a molecule having been previously excited.
  • the luminescent particles can be incorporated into an ink thus allowing the marking of objects. They can therefore provide a means of identification, generally invisible to the naked eye, the detection of which may require a specific excitation wavelength.
  • the document FR 2 846 445 describes a method of authenticating objects implementing the incorporation of chemical markers by means of a label or an insert for example.
  • CA 2 231 464 discloses a security ink comprising a colored pigment, an organic fluorescent pigment, a dye, and a carrier liquid also acting as a solvent for the dye. This is a simple blend that can be used in particular in inkjet or laser printing techniques.
  • CA 2 678 386 discloses a toner composition comprising a binder, a dye and a fluorescent agent. This composition may especially be in the form of an emulsion. These documents all describe a mixture of components that can be used for tagging and authentication of objects.
  • the particles (colored or non-colored pigments) used in the marking inks are not luminescent. They are simply mixed with luminescent compounds. Nevertheless, luminescent particles have already been described in the prior art.
  • WO 2007/050984 discloses luminescent carbon nanoparticles, whose photo luminescence properties are obtained by grafting a passivating agent on the surface of the particles.
  • WO 2010/014018 discloses luminescent carbon nanoparticles obtained by oxidation of the reaction product between at least one carbohydrate and sulfuric acid.
  • WO 2010/008519 discloses a marker agent comprising a binding agent, a chromophore, nanoparticles which have a core coupled to a passivating agent.
  • the preparation of these luminescent particles generally involves a step of grafting the core of the particle with a compound conferring luminescence properties.
  • the problem to be solved by the present invention relates in particular to the development of inorganic particles having luminescent properties and usable for preparing a black or colored ink.
  • the Applicant has developed heart / shell particles whose shell provides luminescent properties, and whose color depends on the nature of the heart. In addition, the shell does not significantly modify the colorimetric coordinates of the particles.
  • the presence of phosphor modifies as little as possible the optical (color) or physical properties (magnetism for example) of the core of said particles.
  • the present invention relates to a core / shell luminescent particle, the shell comprising an inorganic matrix doped with at least one luminescent element selected from the group of rare earths.
  • the core of this particle comprises at least carbon.
  • the invention also relates to a nanomaterial formed by an agglomerate of a plurality of particles having a core / shell structure.
  • This nanomaterial is a nano- or submicron particle.
  • particles is also meant an agglomerate of particles.
  • the agglomerate of particles is a nanomaterial formed by the agglomeration of said particles.
  • the agglomerate comprises a plurality of luminescent particles coated with an outer shell consisting of an inorganic matrix comprising at least one rare earth phosphor, said particles being bonded together by virtue of the inorganic matrix.
  • the core of the particle has a sub-micron or nanometric size.
  • the core of the particle may contain at least one core material which may be chosen from the group comprising organic pigments; inorganic pigments; metals ; metal oxides; silica; silica derivatives; and their mixtures.
  • the core may especially be carbon in crystalline or amorphous form. It can be carbon black.
  • the heart can thus also include colored pigments. It can especially be Cr 2 0 3 (green); B1VO 4 (yellow); Fe 2 O 3 (red); Ti0 2 (white); and their mixtures.
  • the core may also include a metal (Au, Ag), a metal oxide, silica, a silica derivative such as glass frit (the core may then be transparent).
  • the core of the particle comprises a majority of carbon, that is to say more than 50% by weight of carbon relative to the weight of the core. Even more advantageously, the core comprises more than 90% by weight of carbon, and even more preferably 100% by weight of carbon.
  • the core of the particle may have an intermediate encapsulation layer between the core and the shell. It may especially be a layer of silica or zinc oxide.
  • This intermediate layer ensures insolubility of the heart during the implementation of the latter, in particular to prepare the particle - object of the invention, by forming a shell around the heart.
  • the shell inorganic matrix thus covers the intermediate encapsulation layer.
  • the inorganic matrix forming the shell may in particular be of a material chosen from the group comprising transition metals; lanthanides; and their mixtures.
  • the thickness of the shell can be adjusted according to the depth of the desired color while ensuring the detection of phosphors under excitation.
  • the shell may be in the form of a single layer. It is then a layer of phosphor on the surface of the heart.
  • the shell may be in the form of a coating comprising a plurality of successive layers, at least one of these layers comprising at least one rare earth element luminescent.
  • each of the layers may comprise identical or distinct phosphors at concentrations that may vary from one layer to another.
  • its outer layer may be a functionalization layer with stabilizing or dispersing properties.
  • the shell may be in the form of a layer, layer or particle.
  • the shell is in particle form, that is to say in the form of a coating consisting of inorganic matrix particles
  • the phosphor particles are adsorbed on the surface of the core.
  • the shell is no longer continuous but disjointed.
  • the adhesion of the inorganic matrix particles to the core can be facilitated by the use of charged polymers embedding the core or the particles, or both.
  • These charged polymers may in particular be chosen from groups of macromolecules comprising, in particular, carboxylate, sulphonate, polyallylamine polyethylene imine and polyacrylic functional groups.
  • the shell may comprise at least one layer and particles of inorganic matrix.
  • it may be a shell comprising a particulate coating covered with a continuous layer of phosphor, and optionally a functionalization layer. It can also be a continuous coating of one or more phosphors covered with a particulate coating, optionally followed by functionalization.
  • the inorganic matrix forming the shell is doped with at least one luminescent element chosen from rare earth elements. It may advantageously be chosen from the group comprising Ce; Sm; Eu; Tb; Dy; Er; Tm; Yb; and their mixtures.
  • the luminescent compound is not inserted on the core of the particles by means of a chelating agent, it is integrated by doping within the inorganic matrix of coating forming the shell.
  • the shell may comprise several phosphors, and whatever the shape of the shell.
  • a luminescent optical code can be defined.
  • This multiple core-shell system can thus have unique characteristics in terms of excitation wavelength of the phosphors. Indeed, a single excitation wavelength could give rise to simultaneous transmissions. This type of system could also be identifiable by excitation at several different wavelengths. In this case, the emissions can be detected either simultaneously or individually according to the excitation technique used, thus creating a luminescent optical code.
  • the signature of the luminescent particles according to the invention is specific and unique, it depends on the nature and proportions of the different luminophores, which makes it possible to authenticate the labeled product.
  • the particles according to the invention exhibit coloring characteristics that are distinct from those resulting from the mixing of a luminophore and a colored pigment.
  • the carbon or carbon-based particles of the invention have a spherical shape.
  • Their diameter is preferably between 10 and 500 nanometers, more preferably between 20 and 200 nanometers.
  • the agglomerates of carbon particles, or carbon-based, according to the invention have a spherical shape.
  • Their diameter is preferably between 0.1 and 10 microns, more preferably between 0.5 and 5 microns.
  • the carbon or carbon-based core of the particle has a diameter advantageously between 10 and 500 nanometers, while the thickness of the outer coating (shell) is preferably between 1 and 50 nanometers.
  • the particle according to the invention comprises, by weight relative to the weight of the particle:
  • rare earth element advantageously 0.5 to 5;
  • the weight ratio shell / core is advantageously between 0.1 and 10, more preferably between 0.2 and 5.
  • the present invention also relates to a process for preparing the luminescent core / shell particles described above. It includes the following steps:
  • the luminescence of the particle according to the invention is not obtained by grafting a luminescent compound.
  • the inorganic matrix is advantageously in the form of a metal oxide salt.
  • the rare earth compound used can in particular be a rare earth complex, advantageously in the form of a complex of chloride, nitrate, or acetate.
  • the skilled person will be able to adjust the amount of rare earth added according to the intensity of the desired signal.
  • the method which is the subject of the invention thus makes it possible to prepare said particles under mild conditions. Indeed, the entire process can be performed at room temperature. In general, the precipitation of the particles can result from the reactivity between the different precursors.
  • the inorganic shell thus forms around the heart during the reaction.
  • the core / shell particles of the invention can be integrated in an ink whose coloration is a function of the nature of the core of the particles. Thus particles whose heart is carbon give a black ink.
  • the ink may comprise a carrier liquid which may advantageously be selected from the group comprising water, ethanol, acetone, methyl ethyl ketone, ethyl 3-ethoxypropionate and the like.
  • the particles may be stabilized in the presence of at least one polymer which may especially be chosen from the group comprising polyacrylic acid; PVA (polyvinyl alcohol); PVP (polyvinyl pyrrolidone); poly (allylamine hydrochloride), such as the compound of formula CAS 71550-12-4 for example; PEO (polyethyl oxazoline); PEI (polyethylene imine); PEG (polyethylene glycol); PMMA (polymethyl methacrylate); PVS (poly (vinylsulfate)); PSS (sodium poly (styrene sulfonate)); and their mixtures.
  • PVA polyvinyl alcohol
  • PVP polyvinyl pyrrolidone
  • poly allylamine hydrochloride
  • PEO polyethyl oxazoline
  • PEI polyethylene imine
  • PEG polyethylene glycol
  • PMMA polymethyl methacrylate
  • PVS poly (vinylsulfate)
  • the ink may also be an ink without a carrier liquid, as in the field of screen printing, or offset; a dry ink as in toners. This is particularly the case when the core of the particle is made of pigment (s).
  • the luminescent particles which are the subject of the invention can be used in the field of the fight against counterfeiting, in particular by marking an object.
  • the marking can in particular be carried out by liquid or solid means.
  • it may be the printing of an ink comprising the luminescent particles.
  • the invention therefore also relates to the use of luminescent particles in the field of anti-counterfeiting but also the object comprising a plurality of these luminescent particles.
  • the method of preparation of this object consists in particular in depositing or incorporating on or in a substrate, an ink comprising core / shell luminescent particles, the shell of which comprises an inorganic matrix doped with at least one luminescent element chosen from the group of rare earths .
  • it may be a black or colored ink.
  • the deposition / marking technique may especially be chosen from the group comprising ink jet printing, xerography, elcography, thermography; offset, screen printing, pad printing, and flexography techniques.
  • Particle detection ie identification or authentication
  • a luminescence spectrometer at the excitation wavelength (s) of the phosphor (s).
  • FIG. 1 illustrates a heart / shell particle whose shell is luminescent.
  • Figure 2 illustrates a heart-shell particle whose luminescent shell has several layers.
  • Figure 3 illustrates a heart-shell particle whose luminescent shell is in particulate form.
  • FIG. 4 corresponds to the excitation spectra (intensity vs. wavelength) of particles according to the invention.
  • FIG. 5 corresponds to the emission spectra (intensity vs. wavelength) of particles according to the invention.
  • FIG. 6 represents the graph of the colorimetric coordinate L of particles according to the invention, and according to the prior art. DETAILED DESCRIPTION OF THE INVENTION
  • the luminescent particle heart / shell schematically in Figure 1 has a core (1) of core material, covered with a shell (2) inorganic matrix having one or more luminescent centers.
  • This particle according to the invention is also characterized by its excitation energies ⁇ and emission ⁇ .
  • the particle illustrated in Figure 2 comprises a core (1), coated with a multilayer shell.
  • the first layer (2i) comprises one or more phosphors excitable at the wavelength ⁇ and emitting at wavelengths ⁇ .
  • the shell also comprises n additional layers (2 n ), each of them comprising at least one or more luminophores emitting at the wavelength ⁇ ⁇ .
  • the outer surface of the shell comprises a functionalization layer (3).
  • the particle illustrated in FIG. 3 comprises a core (1), coated with a particulate shell (2) containing at least one or more phosphors excitable at the wavelength ⁇ and emitting at the wavelength ⁇ .
  • the shell is made of a plurality of inorganic matrix particles including the phosphor.
  • An aqueous suspension of carbon powder is prepared.
  • the luminescent material is then added, with stirring, and in the form of a rare earth complex of chloride, nitrate, or acetate.
  • the amount of rare earth added depends on the intensity of the desired signal.
  • a matrix in the form of metal oxide salt is added to the reaction medium.
  • the resulting mixture is stirred and then precipitated.
  • the precipitated particles are then centrifuged, washed with water and dried.
  • the powder obtained is suspended in a colorless ink, by means of polymers adapted to said ink.
  • the resulting ink is black, that is to say the color of the heart of the particles (carbon).
  • Inks comprising particles having different shell / core weight ratios have been prepared.
  • Table 1 Particles prepared according to the invention (1-5) and counterexamples (6-7).
  • FIG. 4 corresponds to the excitation spectra of particles according to the invention (Examples 1-5), as a function of the quantity of phosphor.
  • FIG. 5 corresponds to the emission spectra of particles according to the invention (Examples 1-5), as a function of the quantity of phosphor of the shell.
  • the intensity of the emission signal increases as a function of the amount of phosphor. The amount of doping thus improves the signal detection.
  • Example 7 The black depth of the carbon particles according to the invention (Examples 1-5) was compared with that of carbon particles (Example 6) and with a mixture of carbon particles + phosphor (Example 7).
  • the L coordinate is a component of clarity whose value is between 0 (black) and 100 (white).
  • the other two components are respectively components along the red-green and yellow-blue axes. These are not discussed because they are less affected, or not at all, within the scope of the invention.
  • the carbon particles according to Example 6 have a depth of black less than that of the heart / shell particles of the invention according to Example 5 ( Figure 6). The black depth is more intense for the core / shell particles of Example 5.
  • the particle / phosphor mixture according to Example 7 has a depth of black less than that of the core / shell particles according to Examples 2 to 5.
  • the simple addition of a luminophore mixed with carbon does not have the same coloration characteristics as the particles that are the subject of the invention.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Dispersion Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Inorganic Chemistry (AREA)
  • Luminescent Compositions (AREA)
  • Inks, Pencil-Leads, Or Crayons (AREA)

Abstract

The invention relates to a luminescent core/shell particle wherein the shell comprises an inorganic matrix doped with at least one luminescent element selected from the group of rare earths, and the core comprises carbon.

Description

PARTICULE INORGANIQUE CŒUR/COQUILLE LUMINESCENTE, PROCÉDÉ DE INORGANIC CORE PARTICLE / LUMINESCENT SHELL, METHOD OF
PRÉPARATION ET UTILISATIONPREPARATION AND USE
DOMAINE DE L'INVENTION FIELD OF THE INVENTION
L'invention concerne une particule inorganique cœur/coquille présentant des propriétés de luminescence émanant de la présence d'au moins un élément choisi parmi les terres rares. Le domaine d'utilisation de la présente invention concerne notamment la mise en œuvre de ces particules luminescentes pour marquer des objets dans le cadre de la lutte anti-contrefaçon. The invention relates to an inorganic core / shell particle having luminescence properties emanating from the presence of at least one element selected from rare earths. The field of use of the present invention relates in particular to the use of these luminescent particles for marking objects in the context of the fight against counterfeiting.
ÉTAT ANTÉRIEUR DE LA TECHNIQUE PRIOR STATE OF THE TECHNIQUE
La luminescence correspond à l'émission de lumière de manière rapide (fluorescence) ou plus lente (phosphorescence) suite à l'absorption de photons par une molécule ayant été préalablement excitée. Les particules luminescentes peuvent être incorporées au sein d'une encre permettant ainsi le marquage d'objets. Elles peuvent donc apporter un moyen d'identification, généralement invisible à l'œil nu, dont la détection peut requérir une longueur d'onde d'excitation spécifique. Par exemple, le document FR 2 846 445 décrit un procédé d'authentifîcation d'objets mettant en œuvre l'incorporation de marqueurs chimiques au moyen d'une étiquette ou d'un insert par exemple. Luminescence corresponds to the emission of light in a fast manner (fluorescence) or slower (phosphorescence) following the absorption of photons by a molecule having been previously excited. The luminescent particles can be incorporated into an ink thus allowing the marking of objects. They can therefore provide a means of identification, generally invisible to the naked eye, the detection of which may require a specific excitation wavelength. For example, the document FR 2 846 445 describes a method of authenticating objects implementing the incorporation of chemical markers by means of a label or an insert for example.
Le document CA 2 231 464 décrit une encre de sécurité comprenant un pigment coloré, un pigment fluorescent organique, un colorant, et un liquide véhicule agissant également en tant que solvant du colorant. Il s'agit d'un simple mélange pouvant être notamment utilisé dans les techniques d'impression par jet d'encre ou laser. CA 2 231 464 discloses a security ink comprising a colored pigment, an organic fluorescent pigment, a dye, and a carrier liquid also acting as a solvent for the dye. This is a simple blend that can be used in particular in inkjet or laser printing techniques.
Le document CA 2 678 386 décrit une composition de toners d'impression comprenant un agent liant, un colorant et un agent fluorescent. Cette composition peut notamment se présenter sous la forme d'une émulsion. Ces documents décrivent tous un mélange de composants pouvant être utilisé pour le marquage et l'authentification d'objets. CA 2 678 386 discloses a toner composition comprising a binder, a dye and a fluorescent agent. This composition may especially be in the form of an emulsion. These documents all describe a mixture of components that can be used for tagging and authentication of objects.
De manière générale, les particules (pigments colorés ou non) mises en œuvre dans les encres de marquage ne sont pas luminescentes. Elles sont simplement mélangées à des composés luminescents. Néanmoins, des particules luminescentes ont déjà été décrites dans l'art antérieur. In general, the particles (colored or non-colored pigments) used in the marking inks are not luminescent. They are simply mixed with luminescent compounds. Nevertheless, luminescent particles have already been described in the prior art.
Par exemple, le document WO 2007/050984 divulgue des nanoparticules de carbone luminescentes, dont les propriétés de photo luminescence sont obtenues par greffage d'un agent de passivation à la surface des particules. For example, WO 2007/050984 discloses luminescent carbon nanoparticles, whose photo luminescence properties are obtained by grafting a passivating agent on the surface of the particles.
Le document WO 2010/014018 décrit des nanoparticules de carbone luminescentes obtenues par oxydation du produit de réaction entre au moins un carbohydrate et l'acide sulfurique. WO 2010/014018 discloses luminescent carbon nanoparticles obtained by oxidation of the reaction product between at least one carbohydrate and sulfuric acid.
Le document WO 2010/008519 décrit un agent marqueur comprenant un agent liant, un chromophore, des nanoparticules qui présentent un cœur couplé à un agent de passivation. WO 2010/008519 discloses a marker agent comprising a binding agent, a chromophore, nanoparticles which have a core coupled to a passivating agent.
Toutefois, ces trois derniers documents ne concernent pas le domaine de la lutte anticontrefaçon. D'autre part, la préparation de ces particules luminescentes fait généralement intervenir une étape de greffage du cœur de la particule avec un composé conférant des propriétés de luminescence. However, these last three documents do not concern the field of the fight against counterfeiting. On the other hand, the preparation of these luminescent particles generally involves a step of grafting the core of the particle with a compound conferring luminescence properties.
Quoi qu'il en soit, il existe un besoin de développer des particules pouvant être incorporées au sein d'encres noires ou colorées. Il est en effet relativement complexe de préparer une encre colorée présentant des propriétés de luminescence, étant donné que les rayonnements optiques (excitation et émission) sont absorbés intégralement ou en partie par les encres. Be that as it may, there is a need to develop particles that can be incorporated into black or colored inks. It is indeed relatively complex to prepare a colored ink having luminescence properties, since the optical radiation (excitation and emission) are absorbed in whole or in part by the inks.
Le problème que propose de résoudre la présente invention concerne notamment la mise au point de particules inorganiques présentant des propriétés luminescentes et utilisables pour préparer une encre noire ou colorée. EXPOSE DE L'INVENTION The problem to be solved by the present invention relates in particular to the development of inorganic particles having luminescent properties and usable for preparing a black or colored ink. SUMMARY OF THE INVENTION
Le Demandeur a mis au point des particules cœur/coquille dont la coquille apporte des propriétés luminescentes, et dont la couleur dépend de la nature du cœur. En outre, la coquille ne modifie pas significativement les coordonnées colorimétriques des particules. The Applicant has developed heart / shell particles whose shell provides luminescent properties, and whose color depends on the nature of the heart. In addition, the shell does not significantly modify the colorimetric coordinates of the particles.
De manière générale, la présence de luminophore modifie le moins possible les propriétés optiques (couleur) ou physiques (magnétisme par exemple) du cœur desdites particules. In general, the presence of phosphor modifies as little as possible the optical (color) or physical properties (magnetism for example) of the core of said particles.
Plus précisément, la présente invention concerne une particule luminescente cœur/coquille, dont la coquille comprend une matrice inorganique dopée avec au moins un élément luminescent choisi dans le groupe des terres rares. En outre, le cœur de cette particule comprend au moins du carbone. More specifically, the present invention relates to a core / shell luminescent particle, the shell comprising an inorganic matrix doped with at least one luminescent element selected from the group of rare earths. In addition, the core of this particle comprises at least carbon.
Plus particulièrement, l'invention concerne également un nanomatériau formé par un agglomérat d'une pluralité de particules à structure cœur/coquille. Ce nanomatériau est une nano- ou submicro- particule. More particularly, the invention also relates to a nanomaterial formed by an agglomerate of a plurality of particles having a core / shell structure. This nanomaterial is a nano- or submicron particle.
Par particules, on entend également un agglomérat de particules. By particles is also meant an agglomerate of particles.
L'agglomérat de particules est un nanomatériau formé par l'agglomération desdites particules. Ainsi selon l'invention, l'agglomérat comprend une pluralité de particules luminescentes revêtues d'une coquille externe constituée d'une matrice inorganique comprenant au moins un luminophore terre rare, lesdites particules étant liées entres elles grâce à la matrice inorganique. The agglomerate of particles is a nanomaterial formed by the agglomeration of said particles. Thus according to the invention, the agglomerate comprises a plurality of luminescent particles coated with an outer shell consisting of an inorganic matrix comprising at least one rare earth phosphor, said particles being bonded together by virtue of the inorganic matrix.
De manière générale, le cœur de la particule présente une taille sub-micrométrique ou nanométrique. Selon un mode de réalisation particulier, outre le carbone, le cœur de la particule peut contenir au moins un matériau de cœur pouvant être choisi dans le groupe comprenant les pigments organiques ; les pigments inorganiques ; les métaux ; les oxydes métalliques ; la silice ; les dérivés de silice ; et leurs mélanges. In general, the core of the particle has a sub-micron or nanometric size. According to a particular embodiment, in addition to carbon, the core of the particle may contain at least one core material which may be chosen from the group comprising organic pigments; inorganic pigments; metals ; metal oxides; silica; silica derivatives; and their mixtures.
Le cœur peut notamment être en carbone sous forme cristalline ou amorphe. Il peut s'agir de noir de carbone. Le cœur peut ainsi comprendre également des pigments colorés. Il peut notamment s'agir de Cr203 (vert) ; B1VO4 (jaune) ; Fe203 (rouge) ; de Ti02 (blanc) ; et leurs mélanges. Le cœur peut également comprendre un métal (Au, Ag), un oxyde métallique, de la silice, un dérivé de la silice tel que la fritte de verre (le cœur peut alors être transparent). The core may especially be carbon in crystalline or amorphous form. It can be carbon black. The heart can thus also include colored pigments. It can especially be Cr 2 0 3 (green); B1VO 4 (yellow); Fe 2 O 3 (red); Ti0 2 (white); and their mixtures. The core may also include a metal (Au, Ag), a metal oxide, silica, a silica derivative such as glass frit (the core may then be transparent).
De manière avantageuse, le cœur de la particule comprend en majorité du carbone, c'est-à-dire plus de 50% en poids de carbone par rapport au poids du cœur. De manière encore plus avantageuse, le cœur comprend plus de 90% en poids de carbone, et encore plus préférentiellement 100% en poids de carbone. Advantageously, the core of the particle comprises a majority of carbon, that is to say more than 50% by weight of carbon relative to the weight of the core. Even more advantageously, the core comprises more than 90% by weight of carbon, and even more preferably 100% by weight of carbon.
Selon un mode de réalisation particulier, le cœur de la particule peut présenter une couche d'encapsulation intermédiaire, comprise entre le cœur et la coquille. Il peut notamment s'agir d'une couche de silice ou d'oxyde de zinc. According to a particular embodiment, the core of the particle may have an intermediate encapsulation layer between the core and the shell. It may especially be a layer of silica or zinc oxide.
Cette couche intermédiaire assure l'insolubilité du cœur lors de la mise en œuvre de ce dernier, notamment pour préparer la particule - objet de l'invention, par formation d'une coquille autour du cœur. Selon ce mode de réalisation particulier, la coquille (matrice inorganique) recouvre donc la couche intermédiaire d'encapsulation. This intermediate layer ensures insolubility of the heart during the implementation of the latter, in particular to prepare the particle - object of the invention, by forming a shell around the heart. According to this particular embodiment, the shell (inorganic matrix) thus covers the intermediate encapsulation layer.
La matrice inorganique formant la coquille peut notamment être en un matériau choisi dans le groupe comprenant les métaux de transitions ; les lanthanides ; et leurs mélanges. The inorganic matrix forming the shell may in particular be of a material chosen from the group comprising transition metals; lanthanides; and their mixtures.
L'épaisseur de la coquille peut être ajustée en fonction de la profondeur de la couleur souhaitée tout en assurant la détection des luminophores sous excitation. La coquille peut se présenter sous forme d'une couche unique. Il s'agit alors d'une couche de luminophore à la surface du cœur. The thickness of the shell can be adjusted according to the depth of the desired color while ensuring the detection of phosphors under excitation. The shell may be in the form of a single layer. It is then a layer of phosphor on the surface of the heart.
Selon un mode de réalisation particulier, la coquille peut se présenter sous la forme d'un enrobage comprenant une pluralité de couches successives, au moins l'une de ces couches comprenant au moins un élément luminescent terre rare. Dans ce cas, chacune des couches peut comprendre des luminophores identiques ou distincts, à des concentrations pouvant varier d'une couche à l'autre. According to a particular embodiment, the shell may be in the form of a coating comprising a plurality of successive layers, at least one of these layers comprising at least one rare earth element luminescent. In this case, each of the layers may comprise identical or distinct phosphors at concentrations that may vary from one layer to another.
Quelle que soit la forme de la coquille, sa couche externe peut être une couche de fonctionnalisation présentant des propriétés de stabilisation ou de dispersion. Whatever the shape of the shell, its outer layer may be a functionalization layer with stabilizing or dispersing properties.
La coquille peut se présenter sous forme de couche, de couches ou particulaire. The shell may be in the form of a layer, layer or particle.
Dans le cas particulier où la coquille est sous forme particulaire, c'est-à-dire sous forme d'un enrobage constitué de particules de matrice inorganique, les particules de luminophores sont adsorbées à la surface du cœur. La coquille n'est donc plus continue mais disjointe. L'adhésion des particules de matrice inorganique sur le cœur peut être facilitée par l'utilisation de polymères chargés enrobant le cœur ou les particules, voire les deux. Ces polymères chargés peuvent notamment être choisis dans les groupes de macro molécules comprenant notamment des fonctions carboxylates, sulfonates, polyallylamine polyéthylène imine, polyacrylique etc. In the particular case where the shell is in particle form, that is to say in the form of a coating consisting of inorganic matrix particles, the phosphor particles are adsorbed on the surface of the core. The shell is no longer continuous but disjointed. The adhesion of the inorganic matrix particles to the core can be facilitated by the use of charged polymers embedding the core or the particles, or both. These charged polymers may in particular be chosen from groups of macromolecules comprising, in particular, carboxylate, sulphonate, polyallylamine polyethylene imine and polyacrylic functional groups.
Selon un autre mode de réalisation particulier, la coquille peut comprendre au moins une couche et des particules de matrice inorganique. Par exemple, il peut s'agir d'une coquille comprenant un enrobage particulaire recouvert d'une couche continue de luminophore, et éventuellement d'une couche de fonctionnalisation. Il peut également s'agir d'un enrobage continu d'un ou plusieurs luminophores, recouvert d'un enrobage particulaire, éventuellement suivi par une fonctionnalisation. Comme déjà indiqué, la matrice inorganique formant la coquille est dopée avec au moins un élément luminescent choisi parmi les terres rares. Il peut être avantageusement choisi dans le groupe comprenant Ce ; Sm ; Eu ; Tb ; Dy ; Er ; Tm ; Yb ; et leurs mélanges. Le composé luminescent n'est pas inséré sur le cœur des particules au moyen d'un agent chélatant, il est intégré par dopage au sein de la matrice inorganique d'enrobage formant la coquille. According to another particular embodiment, the shell may comprise at least one layer and particles of inorganic matrix. For example, it may be a shell comprising a particulate coating covered with a continuous layer of phosphor, and optionally a functionalization layer. It can also be a continuous coating of one or more phosphors covered with a particulate coating, optionally followed by functionalization. As already indicated, the inorganic matrix forming the shell is doped with at least one luminescent element chosen from rare earth elements. It may advantageously be chosen from the group comprising Ce; Sm; Eu; Tb; Dy; Er; Tm; Yb; and their mixtures. The luminescent compound is not inserted on the core of the particles by means of a chelating agent, it is integrated by doping within the inorganic matrix of coating forming the shell.
Il ne s'agit pas d'une fonctionnalisation de la surface des cœurs de particules mais d'une couche enrobante formée par la matrice inorganique d'enrobage. Selon un mode de réalisation particulier, la coquille peut comprendre plusieurs luminophores, et ce quelle que soit la forme de la coquille. Ainsi, un code optique luminescent peut être défini. Ce système cœur-coquille multiple peut ainsi présenter des caractéristiques uniques en terme de longueur d'onde d'excitation des luminophores. En effet, une seule longueur d'onde d'excitation pourrait donner lieu à des émissions simultanées. Ce type de système pourrait également être identifiable par excitation à plusieurs longueurs d'ondes différentes. Dans ce cas, les émissions peuvent être détectées soit simultanément, soit individuellement selon la technique d'excitation utilisée, créant ainsi un code optique luminescent. This is not a functionalization of the surface of the cores of particles but of a coating layer formed by the inorganic matrix of coating. According to a particular embodiment, the shell may comprise several phosphors, and whatever the shape of the shell. Thus, a luminescent optical code can be defined. This multiple core-shell system can thus have unique characteristics in terms of excitation wavelength of the phosphors. Indeed, a single excitation wavelength could give rise to simultaneous transmissions. This type of system could also be identifiable by excitation at several different wavelengths. In this case, the emissions can be detected either simultaneously or individually according to the excitation technique used, thus creating a luminescent optical code.
En effet, au moyen d'un spectromètre de luminescence, il est possible de détecter et de quantifier les signaux émis par chacun des éléments terre rare introduits lors de la constitution de la coquille. La signature des particules luminescentes selon l'invention est spécifique et unique, elle dépend de la nature et des proportions des différents luminophores, ce qui permet d'authentifier le produit marqué. Indeed, by means of a luminescence spectrometer, it is possible to detect and quantify the signals emitted by each of the rare earth elements introduced during the constitution of the shell. The signature of the luminescent particles according to the invention is specific and unique, it depends on the nature and proportions of the different luminophores, which makes it possible to authenticate the labeled product.
De manière générale, les particules selon l'invention présentent des caractéristiques de coloration distinctes de celles résultant du mélange d'un luminophore et d'un pigment coloré. In general, the particles according to the invention exhibit coloring characteristics that are distinct from those resulting from the mixing of a luminophore and a colored pigment.
De manière avantageuse, les particules de carbone, ou à base de carbone, de l'invention présentent une forme sphérique. Leur diamètre est préférentiellement compris entre 10 et 500 nano mètres, plus avantageusement encore entre 20 et 200 nanomètres. Advantageously, the carbon or carbon-based particles of the invention have a spherical shape. Their diameter is preferably between 10 and 500 nanometers, more preferably between 20 and 200 nanometers.
De manière avantageuse, les agglomérats de particules de carbone, ou à base de carbone, selon l'invention présentent une forme sphérique. Leur diamètre est préférentiellement compris entre 0,1 et 10 micromètres, plus avantageusement encore entre 0,5 et 5 micromètres. Advantageously, the agglomerates of carbon particles, or carbon-based, according to the invention have a spherical shape. Their diameter is preferably between 0.1 and 10 microns, more preferably between 0.5 and 5 microns.
Le cœur en carbone, ou à base de carbone, de la particule présente un diamètre avantageusement compris entre 10 et 500 nanomètres, alors que l'épaisseur du revêtement externe (coquille) est préférentiellement comprise entre 1 et 50 nanomètres. De manière générale, la particule selon l'invention comprend, en poids par rapport au poids de la particule : The carbon or carbon-based core of the particle has a diameter advantageously between 10 and 500 nanometers, while the thickness of the outer coating (shell) is preferably between 1 and 50 nanometers. In general, the particle according to the invention comprises, by weight relative to the weight of the particle:
10 à 90 % de matériau de cœur, avantageusement de 25 à 75 ;  10 to 90% core material, preferably 25 to 75;
0,1 à 10 % d'élément terre rare, avantageusement de 0,5 à 5 ;  0.1 to 10% rare earth element, advantageously 0.5 to 5;
- 10 à 90 % de matrice inorganique, avantageusement de 25 à 75. 10 to 90% of inorganic matrix, advantageously 25 to 75.
Le rapport en poids coquille/cœur est avantageusement compris entre 0,1 et 10, plus avantageusement encore entre 0,2 et 5. The weight ratio shell / core is advantageously between 0.1 and 10, more preferably between 0.2 and 5.
La présente invention concerne également un procédé de préparation des particules cœur/coquille luminescentes décrites ci-dessus. Il comprend notamment les étapes suivantes : The present invention also relates to a process for preparing the luminescent core / shell particles described above. It includes the following steps:
préparation d'une suspension aqueuse de matériau de cœur des particules ;  preparing an aqueous suspension of core material of the particles;
addition sous agitation d'au moins un composé de terre rare à cette suspension aqueuse de matériau de cœur des particules ;  stirred addition of at least one rare earth compound to this aqueous suspension of core material of the particles;
addition sous agitation d'au moins un précurseur de matrice inorganique ;  stirred addition of at least one inorganic matrix precursor;
mélange du milieu réactionne 1, puis précipitation de particules cœur/coquille luminescentes ;  mixture of the reaction medium 1, then precipitation of luminescent heart / shell particles;
optionnellement centrifugation des particules ;  optionally centrifugation of the particles;
lavage des particules, avantageusement à l'eau, puis séchage.  washing the particles, preferably with water, and then drying.
Contrairement aux particules de l'art antérieur, la luminescence de la particule selon l'invention n'est pas obtenue par greffage d'un composé luminescent. La matrice inorganique se présente avantageusement sous forme de sel d'oxyde métallique. Unlike the particles of the prior art, the luminescence of the particle according to the invention is not obtained by grafting a luminescent compound. The inorganic matrix is advantageously in the form of a metal oxide salt.
Le composé de terre rare mis en œuvre peut notamment être un complexe de terre rare, avantageusement sous forme d'un complexe de chlorure, nitrate, ou acétate. The rare earth compound used can in particular be a rare earth complex, advantageously in the form of a complex of chloride, nitrate, or acetate.
L'homme du métier saura ajuster la quantité de terre rare ajoutée en fonction de l'intensité du signal désirée. The skilled person will be able to adjust the amount of rare earth added according to the intensity of the desired signal.
Le procédé objet de l'invention permet ainsi de préparer lesdites particules dans des conditions clémentes. En effet, l'intégralité du procédé peut être réalisée à la température ambiante. De manière générale, la précipitation des particules peut résulter de la réactivité entre les différents précurseurs. La coquille inorganique se forme ainsi autour du cœur lors de la réaction. Les particules cœur/coquille de l'invention peuvent être intégrées dans une encre dont la coloration est fonction de la nature du cœur des particules. Ainsi des particules dont le cœur est en carbone donnent une encre noire. The method which is the subject of the invention thus makes it possible to prepare said particles under mild conditions. Indeed, the entire process can be performed at room temperature. In general, the precipitation of the particles can result from the reactivity between the different precursors. The inorganic shell thus forms around the heart during the reaction. The core / shell particles of the invention can be integrated in an ink whose coloration is a function of the nature of the core of the particles. Thus particles whose heart is carbon give a black ink.
L'encre peut comprendre un liquide véhicule pouvant être avantageusement choisi dans le groupe comprenant l'eau, l'éthanol, l'acétone, la méthyléthylcétone, le 3- éthoxypropionate d'éthyle etc. The ink may comprise a carrier liquid which may advantageously be selected from the group comprising water, ethanol, acetone, methyl ethyl ketone, ethyl 3-ethoxypropionate and the like.
Dans ce cas, les particules peuvent être stabilisées en présence d'au moins un polymère pouvant notamment être choisi dans le groupe comprenant l'acide polyacrylique ; le PVA (alcool polyvynilique) ; le PVP (polyvynil pyrolidone) ; le poly(allylamine hydrochlorure), tel que le composé de formule CAS 71550-12-4 par exemple ; le PEO (polyethyl oxazoline) ; la PEI (polyethylene imine) ; le PEG (polyethylene glycol) ; le PMMA (polymethacrylate de méthyle) ; le PVS (poly(vinylsulfate)) ; le PSS (poly( styrène sulfonate) de sodium) ; et leurs mélanges. In this case, the particles may be stabilized in the presence of at least one polymer which may especially be chosen from the group comprising polyacrylic acid; PVA (polyvinyl alcohol); PVP (polyvinyl pyrrolidone); poly (allylamine hydrochloride), such as the compound of formula CAS 71550-12-4 for example; PEO (polyethyl oxazoline); PEI (polyethylene imine); PEG (polyethylene glycol); PMMA (polymethyl methacrylate); PVS (poly (vinylsulfate)); PSS (sodium poly (styrene sulfonate)); and their mixtures.
L'encre peut également être une encre sans liquide véhicule comme dans le domaine de la sérigraphie, ou de l'offset ; une encre sèche comme dans les toners. Ceci est particulièrement le cas lorsque le cœur de la particule est constitué de pigment(s). De manière générale, les particules luminescentes objet de l'invention peuvent être utilisées dans le domaine de la lutte anti contrefaçon, notamment par marquage d'un objet. The ink may also be an ink without a carrier liquid, as in the field of screen printing, or offset; a dry ink as in toners. This is particularly the case when the core of the particle is made of pigment (s). In general, the luminescent particles which are the subject of the invention can be used in the field of the fight against counterfeiting, in particular by marking an object.
Le marquage peut notamment être réalisé par voie liquide ou solide. Par exemple, il peut s'agir de l'impression d'une encre comprenant les particules luminescentes. The marking can in particular be carried out by liquid or solid means. For example, it may be the printing of an ink comprising the luminescent particles.
L'invention concerne donc également l'utilisation des particules luminescentes dans le domaine de la lutte anti contrefaçon mais aussi l'objet comprenant une pluralité de ces particules luminescentes. Le procédé de préparation de cet objet consiste notamment à déposer ou incorporer sur ou dans un substrat, une encre comprenant des particules luminescentes cœur/coquille, dont la coquille comprend une matrice inorganique dopée avec au moins un élément luminescent choisi dans le groupe des terres rares. The invention therefore also relates to the use of luminescent particles in the field of anti-counterfeiting but also the object comprising a plurality of these luminescent particles. The method of preparation of this object consists in particular in depositing or incorporating on or in a substrate, an ink comprising core / shell luminescent particles, the shell of which comprises an inorganic matrix doped with at least one luminescent element chosen from the group of rare earths .
En fonction de la nature du cœur des particules, il peut s'agir d'une encre noire ou colorée. Depending on the nature of the heart of the particles, it may be a black or colored ink.
La technique de dépôt/marquage peut notamment être choisie dans le groupe comprenant l'impression par jet d'encre, xérographie, elcographie, thermographie ; les techniques offset, sérigraphie, tampographie, et flexographie. The deposition / marking technique may especially be chosen from the group comprising ink jet printing, xerography, elcography, thermography; offset, screen printing, pad printing, and flexography techniques.
D'autres techniques de dépôt/marquage peuvent également être mises en œuvre, l'incorporation dans la masse, ou Pextrusion. Other deposition / marking techniques can also be implemented, incorporation into the mass, or extrusion.
La détection des particules, c'est-à-dire l'identification ou l'authentification, est réalisée au moyen d'un spectromètre de luminescence, à la ou aux longueurs d'onde d'excitation du ou des luminophores. L'invention et les avantages qui en découlent ressortiront mieux des figures et exemples suivants donnés afin d'illustrer l'invention et non de manière limitative. Particle detection, ie identification or authentication, is performed by means of a luminescence spectrometer at the excitation wavelength (s) of the phosphor (s). The invention and the advantages thereof will appear more clearly from the following figures and examples given to illustrate the invention and not in a limiting manner.
DESCRIPTION DES FIGURES La figure 1 illustre une particule de type cœur/coquille dont la coquille est luminescente. DESCRIPTION OF THE FIGURES FIG. 1 illustrates a heart / shell particle whose shell is luminescent.
La figure 2 illustre une particule de type cœur/coquille dont la coquille luminescente présente plusieurs couches.  Figure 2 illustrates a heart-shell particle whose luminescent shell has several layers.
La figure 3 illustre une particule de type cœur/coquille dont la coquille luminescente se présente sous forme particulaire.  Figure 3 illustrates a heart-shell particle whose luminescent shell is in particulate form.
La figure 4 correspond aux spectres d'excitation (intensité vs. longueur d'onde) de particules selon l'invention.  FIG. 4 corresponds to the excitation spectra (intensity vs. wavelength) of particles according to the invention.
La figure 5 correspond aux spectres d'émission (intensité vs. longueur d'onde) de particules selon l'invention.  FIG. 5 corresponds to the emission spectra (intensity vs. wavelength) of particles according to the invention.
La figure 6 représente le graphe de la coordonnée colorimétrique L de particules selon l'invention, et selon l'art antérieur. DESCRIPTION DÉTAILLÉE DE L'INVENTION FIG. 6 represents the graph of the colorimetric coordinate L of particles according to the invention, and according to the prior art. DETAILED DESCRIPTION OF THE INVENTION
La particule luminescente cœur/coquille schématisée sur la figure 1 présente un cœur (1) en matériau de cœur, recouvert d'une coquille (2) en matrice inorganique comportant un ou plusieurs centres luminescents. Cette particule selon l'invention est également caractérisée par ses énergies d'excitation λ et d'émission λι.  The luminescent particle heart / shell schematically in Figure 1 has a core (1) of core material, covered with a shell (2) inorganic matrix having one or more luminescent centers. This particle according to the invention is also characterized by its excitation energies λ and emission λι.
La particule illustrée par la figure 2 comprend un cœur (1), enrobé par une coquille multicouches. La première couche (2i) comprend un ou plusieurs luminophores excitables à la longueur d'onde λ et émettant aux longueurs d'onde λι. La coquille comprend également n couches supplémentaires (2n), chacune d'entre elles comprenant au moins un voire plusieurs luminophores émettant à la longueur d'onde λη. En outre, la surface externe de la coquille comprend une couche de fonctionnalisation (3). La particule illustrée par la figure 3 comprend un cœur (1), enrobé par une coquille particulaire (2) contenant au moins un voire plusieurs luminophores excitable à la longueur d'onde λ et émettant à la longueur d'onde λι. La coquille est constituée d'une pluralité de particules de matrice inorganique comprenant le luminophore. EXEMPLES DE RÉALISATION DE L'INVENTION The particle illustrated in Figure 2 comprises a core (1), coated with a multilayer shell. The first layer (2i) comprises one or more phosphors excitable at the wavelength λ and emitting at wavelengths λι. The shell also comprises n additional layers (2 n ), each of them comprising at least one or more luminophores emitting at the wavelength λ η . In addition, the outer surface of the shell comprises a functionalization layer (3). The particle illustrated in FIG. 3 comprises a core (1), coated with a particulate shell (2) containing at least one or more phosphors excitable at the wavelength λ and emitting at the wavelength λι. The shell is made of a plurality of inorganic matrix particles including the phosphor. EXAMPLES OF CARRYING OUT THE INVENTION
Une suspension aqueuse de poudre de carbone est préparée. An aqueous suspension of carbon powder is prepared.
Le matériau luminescent est ensuite ajouté, sous agitation, et sous forme d'un complexe terre rare de chlorure, nitrate, ou acétate. La quantité de terre rare ajoutée dépend de l'intensité du signal désirée.  The luminescent material is then added, with stirring, and in the form of a rare earth complex of chloride, nitrate, or acetate. The amount of rare earth added depends on the intensity of the desired signal.
Ensuite, une matrice sous forme de sel d'oxyde métallique est ajoutée dans le milieu réactionnel. Le mélange résultant est agité, puis précipité. Les particules précipitées sont ensuite centrifugées, lavées à l'eau et séchées. Then, a matrix in the form of metal oxide salt is added to the reaction medium. The resulting mixture is stirred and then precipitated. The precipitated particles are then centrifuged, washed with water and dried.
La poudre obtenue est mise en suspension dans une encre incolore, au moyen de polymères adaptés à ladite encre. The powder obtained is suspended in a colorless ink, by means of polymers adapted to said ink.
L'encre résultante est noire, c'est-à-dire de la couleur du cœur des particules (carbone). The resulting ink is black, that is to say the color of the heart of the particles (carbon).
Des encres comprenant des particules présentant différents rapport en poids coquille/cœur ont été préparées. Tableau 1 : Particules préparées selon l'invention (1-5) et contre-exemples (6-7). Inks comprising particles having different shell / core weight ratios have been prepared. Table 1: Particles prepared according to the invention (1-5) and counterexamples (6-7).
particules en carbone ne comprenant pas de luminophore ni de matrice inorganique. ' Mélange de particules de carbone et de luminophores synthétisés précédemment, et ne comprenant pas de matrice inorganique. Il ne s'agit pas de particules cœur/coquille mais d'un simple mélange de deux poudres : une poudre noire et une poudre luminescente. MEK = méthyléthylcétone carbon particles not comprising phosphor or inorganic matrix. Mixture of carbon particles and luminophores synthesized previously, and comprising no inorganic matrix. It is not about heart / shell particles but a simple mixture of two powders: a black powder and a luminescent powder. MEK = methyl ethyl ketone
La figure 4 correspond aux spectres d'excitation de particules selon l'invention (exemples 1-5), en fonction de la quantité de luminophore. FIG. 4 corresponds to the excitation spectra of particles according to the invention (Examples 1-5), as a function of the quantity of phosphor.
La figure 5 correspond aux spectres d'émission de particules selon l'invention (exemples 1-5), en fonction de la quantité de luminophore de la coquille. De manière générale, l'intensité du signal d'émission augmente en fonction de la quantité de luminophore. La quantité de dopage améliore ainsi la détection du signal. Plus l'épaisseur de la coquille est importante, plus l'intensité du signal d'émission est importante. FIG. 5 corresponds to the emission spectra of particles according to the invention (Examples 1-5), as a function of the quantity of phosphor of the shell. In general, the intensity of the emission signal increases as a function of the amount of phosphor. The amount of doping thus improves the signal detection. The greater the thickness of the shell, the higher the intensity of the emission signal.
La profondeur du noir des particules de carbone selon l'invention (exemples 1-5) a été comparée à celle de particules en carbone (exemple 6) et à un mélange de particules en carbone + luminophore (exemple 7). The black depth of the carbon particles according to the invention (Examples 1-5) was compared with that of carbon particles (Example 6) and with a mixture of carbon particles + phosphor (Example 7).
Dans le système CIE Lab, la coordonnée L est une composante de clarté dont la valeur est comprise entre 0 (noir) et 100 (blanc). Les deux autres composantes (a et b) sont respectivement des composantes selon les axes rouge-vert et jaune-bleu. Ces dernières ne sont pas discutées car elles sont moins affectées, ou pas du tout, dans le cadre de l'invention. In the CIE Lab system, the L coordinate is a component of clarity whose value is between 0 (black) and 100 (white). The other two components (a and b) are respectively components along the red-green and yellow-blue axes. These are not discussed because they are less affected, or not at all, within the scope of the invention.
Il est à noter que les particules de carbone selon l'exemple 6 présentent une profondeur de noir inférieure à celle des particules cœur/coquille de l'invention selon l'exemple 5 (figure 6). La profondeur du noir est plus intense pour les particules cœur/coquille de l'exemple 5. It should be noted that the carbon particles according to Example 6 have a depth of black less than that of the heart / shell particles of the invention according to Example 5 (Figure 6). The black depth is more intense for the core / shell particles of Example 5.
D'autre part, le mélange particules/luminophore selon l'exemple 7 présente une profondeur du noir inférieure à celle des particules cœur/coquille selon les exemples 2 à 5. La simple addition d'un luminophore en mélange avec du carbone (exemple 7) ne présente pas les mêmes caractéristiques de coloration que les particules objet de l'invention. On the other hand, the particle / phosphor mixture according to Example 7 has a depth of black less than that of the core / shell particles according to Examples 2 to 5. The simple addition of a luminophore mixed with carbon (Example 7 ) does not have the same coloration characteristics as the particles that are the subject of the invention.

Claims

REVENDICATIONS
Particule luminescente cœur/coquille, caractérisée en ce que la coquille comprend une matrice inorganique dopée avec au moins un élément luminescent choisi dans le groupe des terres rares, et en ce que le cœur comprend au moins du carbone. Luminescent particle core / shell, characterized in that the shell comprises an inorganic matrix doped with at least one luminescent element selected from the group of rare earths, and in that the core comprises at least carbon.
Particule luminescente cœur/coquille selon la revendication 1, caractérisée en ce que le cœur comprend en outre au moins un matériau choisi dans le groupe comprenant les pigments organiques ; les pigments inorganiques ; les métaux ; les oxydes métalliques ; la silice ; les dérivés de silice ; et leurs mélanges. A core / shell light-emitting particle according to claim 1, characterized in that the core further comprises at least one material selected from the group consisting of organic pigments; inorganic pigments; metals ; metal oxides; silica; silica derivatives; and their mixtures.
Particule luminescente cœur/coquille selon l'une des revendications précédentes, caractérisée en ce que la matrice inorganique est en un matériau choisi dans le groupe comprenant les métaux de transitions ; les lanthanides et leurs mélanges. Core / shell phosphor according to one of the preceding claims, characterized in that the inorganic matrix is of a material selected from the group consisting of transition metals; lanthanides and their mixtures.
Particule luminescente cœur/coquille selon l'une des revendications précédentes, caractérisée en ce que l'élément luminescent terre rare est choisi dans le groupe comprenant Ce ; Sm ; Eu ; Tb ; Dy ; Er ; Tm ; Yb ; et leurs mélanges. Core / shell phosphor according to one of the preceding claims, characterized in that the rare earth element is selected from the group consisting of Ce; Sm; Eu; Tb; Dy; Er; Tm; Yb; and their mixtures.
Particule luminescente cœur/coquille selon l'une des revendications précédentes, caractérisée en ce que la coquille se présente sous forme de couche, de couches, ou de particules. Luminescent particle core / shell according to one of the preceding claims, characterized in that the shell is in the form of a layer, layers, or particles.
Particule luminescente cœur/coquille selon l'une des revendications précédentes, caractérisée en ce que l'enrobage comprend plusieurs couches successives, au moins l'une de ces couches comprenant au moins un élément luminescent terre rare. Luminescent particle core / shell according to one of the preceding claims, characterized in that the coating comprises several successive layers, at least one of these layers comprising at least one rare earth element luminescent.
Encre comprenant la particule objet de l'une des revendications précédentes, caractérisée en ce qu'elle comprend en outre un liquide véhicule et au moins un polymère choisi dans le groupe comprenant l'acide polyacrylique ; l'alcool polyvynilique ; le polyvynil pyrolidone ; le poly(ally lamine hydrochlorure) ; le polyethyl oxazoline ; la polyethylene imine ; le polyethylene glycol ; le polymethacrylate de méthyle ; le poly(vinylsulfate) ; le poly( styrène sulfonate) de sodium ; et leurs mélanges. Procédé de préparation de la particule objet de l'une des revendications 1 à 6, selon les étapes consécutives suivantes : An ink comprising the subject particle of one of the preceding claims, characterized in that it further comprises a carrier liquid and at least one polymer selected from the group consisting of polyacrylic acid; polyvinyl alcohol; polyvinyl pyrrolidone; poly (allylamine hydrochloride); polyethyl oxazoline; polyethylene imine; polyethylene glycol; polymethyl methacrylate; poly (vinylsulfate); sodium poly (styrene sulfonate); and their mixtures. Process for the preparation of the subject particle of one of Claims 1 to 6, according to the following consecutive steps:
préparation d'une suspension aqueuse de matériau de cœur des particules ; addition sous agitation d'au moins un composé de terre rare à cette suspension ;  preparing an aqueous suspension of core material of the particles; stirred addition of at least one rare earth compound to this suspension;
addition sous agitation d'au moins un précurseur de matrice inorganique ; mélange du milieu réactionnel, puis précipitation de particules cœur/coquille luminescentes ;  stirred addition of at least one inorganic matrix precursor; mixing the reaction medium and then precipitation of luminescent core / shell particles;
optionnellement centrifugation des particules ;  optionally centrifugation of the particles;
lavage des particules, avantageusement à l'eau, puis séchage.  washing the particles, preferably with water, and then drying.
Objet comprenant une pluralité de particules luminescentes selon l'une des revendications 1 à 6. 10. Procédé de préparation de l'objet selon la revendication 9, par marquage par voie solide ou liquide. Object comprising a plurality of light-emitting particles according to one of Claims 1 to 6. 10. Process for preparing the article according to Claim 9, by solid or liquid labeling.
EP14720643.7A 2013-04-16 2014-03-13 Luminescent inorganic core/shell particle, production method and use Withdrawn EP2986687A1 (en)

Applications Claiming Priority (2)

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FR1353438A FR3004459B1 (en) 2013-04-16 2013-04-16 HEART INORGANIC PARTICLE / LUMINESCENT SHELL, METHOD OF PREPARATION AND USE
PCT/FR2014/050587 WO2014170567A1 (en) 2013-04-16 2014-03-13 Luminescent inorganic core/shell particle, production method and use

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FR3080854B1 (en) * 2018-05-03 2020-05-08 Institut National Des Sciences Appliquees De Rennes POWDER FORMED FROM "HEART-ENVELOPE" PARTICLES COMPRISING COORDINATION POLYMERS BASED ON RARE EARTHS, PROCESS FOR OBTAINING SAME, MATERIAL AND USE THEREOF

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EP1116755A1 (en) * 2000-01-10 2001-07-18 Sicpa Holding S.A. Coating composition, preferably printing ink for security applications, method for producing a coating composition and use of glass ceramics
US7767260B2 (en) * 2003-01-22 2010-08-03 The Board Of Trustees Of The University Of Arkansas Monodisperse core/shell and other complex structured nanocrystals and methods of preparing the same
WO2007050984A2 (en) * 2005-10-27 2007-05-03 Clemson University Fluorescent carbon nanoparticles
FR2904323B1 (en) * 2006-07-28 2008-10-31 Rhodia Recherches & Tech LUMINOPHORES HEART-SHELL.
US7922936B2 (en) * 2006-10-26 2011-04-12 Cabot Corporation Luminescent compositions, methods for making luminescent compositions and inks incorporating the same
JP2010280877A (en) * 2009-06-08 2010-12-16 Nihon Ceratec Co Ltd Phosphor material and light-emitting device
US20130082207A1 (en) * 2011-09-29 2013-04-04 General Electric Company Core-shell phosphor and method of making the same

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