FR2947429A1 - Electrochromic device for applying nail polish on nail, has electrical conductors respectively connected to electrode layers of electrochrome structure, where one of conductors is arranged on distal part extending in front of nail - Google Patents

Abstract

The device (1) has electrical conductors (81, 82) respectively connected to electrode layers (50, 40) of a multi-layer electrochrome structure. One of the conductors is arranged on a distal part extending in front of a nail. Another conductor is extended over a height higher than thickness of the electrode layers. An electric component is electrically connected to one of the conductors. A power supply device includes two terminals placed in electrical contact with the conductors.

Description

The present invention relates to the devices to be applied to human keratin materials, and more particularly but not exclusively to nails. Conventional makeup products, such as nail polish or lipsticks, have the disadvantage of having to be removed and reapplied if we want to change color or optical effect. It would be advantageous when one changes clothes, jewels, or other accessories, to also be able to change the color and / or the optical effects of one's make-up, without having to remove all the makeup and then remix oneself with another makeup product.

In addition, conventional makeup products such as nail polish or lipstick have the disadvantage of not being able to adjust the color after application. Indeed, to change the color, it is necessary to remove all makeup and then remix with another makeup product. It is known from application FR 2 811 206 to apply to the keratin materials electro-optical devices capable of changing appearance through the use of an electrical source. There is a need to remedy the previously mentioned problems of conventional makeup products. There is in particular a need to benefit from production and cost devices compatible with large-scale marketing, easy to use and to set up, able to change in situ appearance and / or to be brought into the appearance chosen by the user before or after application to keratin materials. Electrochromic devices with a multilayer structure, intended to be integrated with glazing, by the publication WO 03/098339 in particular are known. These multilayer structures comprise two electrode layers and between them two electrochromic active layers, separated by an electrolyte layer. The publications Chem. Mater, 2004. 16, 4401-4412, Multicolored Electrochromism in Polymers: Structures and Devices and Combined Electrochromic and Piasmonic Dptical Responses in Conducting Polymer / Metal Nanoparticle Films, New Materials Department, CIDETEC-Center for Electrochemical Technologies, Parque Technology () from San Sebastian, Paseo Miramon 196, E-20009 Donastia-San Sebastian, Spain, disclose other possible arrangements of electrochromic structures. There is a need to benefit from new nail makeup devices. The object of the invention is, according to one of its aspects, an electrochromic device to be applied to the nails, comprising an electrochromic multilayer structure and electrical contacts, at least one of said contacts being disposed on a distal part of the device, extending in front of the nail, for example on a lower face of the device. At least one of the contacts may also be disposed on a slice of the device at its distal end.

Such an arrangement of the contacts makes it possible not to harm the aesthetics of the nail while allowing to electrically power the multilayer structure and / or control its operation or program, where possible. The device can be applied to a nail already made-up or not, or even on a false nail.

The multilayer structure may comprise an electrosensitive stack as defined below, homogeneous or not, and may or may not be provided with a cache as defined below. At least one of the contacts may extend over a height greater than the thickness of an electrode layer of the electrochromic multilayer structure. This can facilitate its power supply by an electrical terminal against which it is supported. One of the contacts may be disposed on a lower face of the device and the other on its edge, at its distal end. This can facilitate the power supply of the device, allowing the user to easily position his finger against electrical power terminals.

The device may comprise an electrosensitive stack comprising active electrochromic layers, electrode layers and an electrolyte layer, and said contacts may be connected directly or indirectly to the respective electrode layers. The electrochromic device may comprise at least one electrical circuit electrically connected to at least one of said contacts. This electrical circuit is for example configured to allow selection of an excitation level of the electrosensitive stack, and may be a simple touch switch and / or potentiometer for a more complex electronic circuit, for example arranged to cyclically modify the excitation of the electrosensitive stack. Non-homogeneous multilayer structure The electrochromic multilayer structure as defined above may comprise an electrosensitive, non-homogeneous stack. at least first and second electrode layers, first and second active electrochromic layers, an electrolyte layer between the electrochromic active layers. In a general manner, the electrode layers may be distinct or not electrochromic active layers. By "non-homogeneous" it is to be understood that in at least two locations of the electrosensitive stack, while this is observed from above, the stack does not have exactly the same structure. For example, at least one of said layers may extend non-homogeneously within the stack, having, for example, a composition and / or a variable thickness, the thickness possibly varying as continuous or discrete, and may be locally nil. The thickness of the layer may vary for example by at least 20% or even 50% or more. This layer may be an electrolyte layer, an electrochromic active layer or an electrode layer. The inhomogeneity of the electrosensitive stack may make it possible to obtain various aspects of interest in cosmetics, for example at least one gradient or a decorative pattern, in particular a color gradient. At least one of the electrochromic active layers may have at least two regions of different respective thicknesses, for example a region having a thickness e, not zero, and a region having zero thickness. Depending on the shape of the outline of one of these regions, it is possible to obtain various patterns. For example, an electrochromic active layer may have two regions whose thicknesses differ by more than 20%, more preferably 50%. At least one layer of the electrosensitive stack may extend with a non-constant thickness over the extent of the stack. The thickness may vary according to one dimension X or to two dimensions X and Y of the stack. The thickness is measured. according to a dimension Z, locally perpendicular to x and Y.

The thickness of at least one layer may vary gradually from one location to another of the layer. The thickness may be zero in at least one location. The layer whose thickness varies may be discontinuous. The disjunct regions of this layer may or may not have the same composition, in order to produce different colors, if any. Each of the layers of the same type, for example the electrochromic active layers, can. present both non-zero thickness regions and zero thickness regions. Regions of non-zero thickness of the two active electrochromic layers can be superimposed exactly within the electrosensitive stack when the latter is observed from above. The zero-thickness regions of the electrochromic active layers may be superimposed with one or more regions of zero thickness of the electrolyte layer and / or the electrode layers. Regions of zero thickness are for example made by removal of material or selective deposition of at least one material of the electrosensitive stack. At least one of the electrochromic active layers may have a thickness varying between two locations of this layer, for example a thickness decreasing linearly between these locations, which may coincide with edges of the electrosensitive stack among other possibilities. Only one of the electrochromic active layers may have a varying thickness, or alternatively the two electrochromic active layers may each have a thickness that varies, the thickness evolving for example decreasing or progressing in the same direction. For a given location of the stack, when it is observed from above, the two electrochromic active layers may have the same thickness or not.

The thickness of the electrolyte layer may also vary, for example linearly, from one location to another of the stack, regardless of a variation or not the thickness of the other layers of the electrosensitive stack. An electrolyte layer with a variable thickness may for example be located between two homogeneous electrochromic active layers, in particular each of constant thickness.

Both the electrode layers, the electrochromic active layers and the electrolyte layer may have regions of zero thickness and regions of non-zero thickness, so as to form a discontinuous stack, allowing for example to create one or more patterns . At least one of the electrochromic or electrolyte active layers may have a non-homogeneous composition. For example, the electrolyte layer and / or at least one electrochromic active layer may have regions having different respective compositions. For example, at least one of the electrochromic active layers may comprise a first region comprising a first polymer and a second region comprising a second polymer, different from the first. These polymers can be chosen to create color differences, for example. The electrolyte layer may comprise regions having different compositions, arranged between homogeneous electrochromic active layers. For example, the electrolyte layer comprises at least two regions made with different materials. Regions of different compositions of the same layer of the electrosensitive stack may or may not have the same thickness. The electrochromic device may comprise at least one screen disposed between two layers of the electrosensitive stack, to locally create a modification of the interaction between these layers. This screen is made for example of polymethylmethacrylate (PMMA) or polyethylene terephthalate (PET). The screen may extend between the electrolyte layer and an electrochromic active layer. The screen may form, depending on its shape or a variation of its thickness or composition, at least one pattern whose visibility depends on the excitation state of the electrochromic device. The screen can be made by transfer, printing or engraving, among other possibilities. The screen may be transparent or not. In the case of a transparent screen, a pattern defined by the screen may appear during the excitation of the device. The thickness of the screen is for example between 1 and 100 microns, preferably between 5 and 30 microns. Multilayer Structure Associated with a Cache The multilayer electrochromic structure as defined above may comprise an electrosensitive stack, homogeneous or not, of at least: the first and second electrode layers, the first and second active electrochromic layers, the multilayer structure including at least one cache for the founation of at least one pattern.

The stack, when not homogeneous, may have any of the characteristics defined above. The cache can be colored or not, opaque or not, and continuous or discontinuous. The cache can be reflective. The cover may be external to the electrosensitive stack.

The cache can form at least one pattern. whose visibility may depend on the excitation state of the electrochromic device. A nail makeup very fashionable, said French manicure, consists of makeup only the tips of his nails, preferably light in order to give the impression of a clean and natural result. However, this type of makeup can sometimes have the disadvantage of appearing too sophisticated. Therefore, it would be advantageous to be able to do as he pleased, and without the need to remove makeup, make disappear this makeup and make it reappear at will. The electrochromic device can thus be arranged so as to achieve a color change at the end of the nail, for example in the shape of a crescent moon, to simulate this type of makeup. The outline of the electrosensitive stack may be in the shape of a crescent moon. Alternatively, a mask is used to partially mask the electrosensitive stack and define a crescent-shaped pattern. The electrosensitive stack can be made to take, depending on its electrical excitation, a color close to that of the cache. By close color, it should be understood that the difference AE in the calorimetric space CIE Lab 1976 is less than or equal to 1.5. Thus, the visibility of the cache may depend on the electrical excitation of the electrochromic device. The cover can be attached to the multilayer structure, before or after it is fixed on the nail for example, or integrated in a support layer adjacent to an electrode layer. The cache can be formed by printing, transferring, engraving, among other possibilities.

The cover is for example made by an ink jet printing on a multilayer structure placed on the nail or ready to be placed on the nail. Where appropriate. the impression of. cache is performed on a removable film. to remove the cache to replace it with another, different pattern.

When the cover is integrated in a support layer, the cover is for example laminated between two films forming the support layer. The cover may comprise a pigment or dye, a layer of metal. a polymeric film, and may optionally include a microrelief intended for example to create optical effects. IO The thickness of the cache. is for example between 1 and 100 microns, preferably between 5 and 30 microns. When the cache is not completely opaque, the cache can act as an optical filter, for example to control light reaching underlying layers. Optically active layer, The electrochromic multilayer structure as defined above may comprise an electrosensitive stack. homogeneous or not, formed of at least: - the first and the second electrode layer, the first and second electrochromic active layer. The electrolyte layer, and further comprising an optically active layer superimposed at least partially on the electrosensitive stack. The optically active layer is for example located above the electrosensitive stack. The optically active layer may, alternatively, be located between two layers of the electrosensitive stack. The optically active layer can still be located under the electrosensitive stack. The optically active layer may be formed of a cache as defined above. The optically active layer may or may not be colored, and may be useful for modifying the appearance of the device. The optically active layer may be luminescent or photochromic and the electrosensitive stack may, depending on its electrical excitation, block more or less at least one optical excitation wavelength of the optically active layer. It is thus possible to control the excitation of the optically active layer by means of the electrosensitive stack, which offers new possibilities of combinations of effects. The optically active layer may extend over the entire electrosensitive stack or be discontinuous, and for example form at least one pattern. The optically active layer may comprise an interference pigment and / or a liquid crystal. The visibility of this interference pigment and / or of this liquid crystal may depend on the excitation of the electrosensitive stack. For example, when the interference pigment or the liquid crystal is situated beneath the electrosensitive stack or within it, the electrosensitive stack can modify an observed color path and / or make the pigment or the liquid crystal more or less visible, forming a more or less dark background under this pigment or liquid crystal. The thickness of the optically active layer is for example between 1 and 100 microns, preferably between 5 and 30 microns. The optically active layer may, where appropriate, be deposited by the user on the surface of the multilayer structure, or may be deposited by printing with a particular pattern if appropriate. The optically active layer may be deposited, for example, on a removable protective layer of the multilayer structure. The optically active layer may be a makeup deposited on the keratin materials and then covered by the electrochromic multilayer structure. Contrast effect The optically active layer may be arranged to generate a contrast effect with at least one region of the electrosensitive stack. By contrast effect it should be understood that a contrast between two apparent regions of the device is changed depending on the excitation of the electrochromic device. This can make a region more or less visible depending on the state of the device or change the perception of a color by the observer. Some colors may indeed appear more or less saturated depending on the surrounding color. Such an optically active layer may comprise an effect pigment selected for example from interferential pigments and metal particles.

The optically active layer may be located above the electrosensitive stack, and for example draw a pattern on its surface. In this case, the contrast of the pattern with its environment depends on the state of excitation of the electrochromic multilayer structure.

The optically active layer may also be located below the electrosensitive stack. In exemplary embodiments, the electrosensitive stack may, depending on its electrical excitation, be substantially the same color as the optically active layer. This can make it possible to modify the visibility of a pattern formed with the optically active layer, depending on the state of excitation of the device. The optically active layer may be deposited on a removable protective layer of the electrochromic multilayer structure. Optically active layer corn. The optically active layer may comprise an interferential pigment or a liquid crystal, the electrochromic multilayer structure being located under the optically active layer. The electrochromic multilayer structure can act as a background of varying color or opacity, making the optically active layer covering it more or less visible. The electrochromic multilayer structure can for example take on the one hand a dark state and on the other hand a clear or transparent state, depending on its electrical excitation. In the dark state, the color or colors of the optically active layer stand out clearly, whereas in the light state the color or colors are more difficult to perceive. The optically active layer may comprise a mother-of-pearl, a goniochromatic pigment or a liquid crystal, chosen especially from those having a low visibility on a light background, for example iridescent pigments. The optically active layer may completely cover the electrochromic structure, or draw a pattern on its surface. Built-in power source The device can have an integrated power source.

The power source may include a battery, an electric accumulator, a capacitor and / or a coil. The energy source can be flexible or rigid. Contacts can be useful for recharging the built-in power source when it is rechargeable.

The energy source can continuously supply, for example for a period greater than 1 h better 4 h, the electrosensitive stack possibly until its depletion. Alternatively, the power supply can be carried out selectively, for example by a switch controllable by the user. A removable insulating tab can isolate at least one terminal of the power source before the first use. Multiple Polymers Within a Single Layer At least one of the electrochromic and electrolyte active layers comprising at least first and second materials, in particular polymers. These polymers may be chosen from electrochromic polymers.

The first and second materials may be juxtaposed, and for example each correspond to a region drawing a pattern. The first and second materials can be disjointed or not. The first and second materials may be mixed, for example to create intermediate colors between those associated with polymers that are mixed.

Adaptation of the device In general, the electrochromic device may be worn by a false plastic nail, for example of the type available from many suppliers of nail salons. Conventionally used false nails have long lengths and must generally be cut before use. Before depositing the electrochromic multilayer structure on such a false nail, for example by coating for at least some layers, the false nail can be cut for example so that the difference between the length and width of the false nail is included between 0.6 and 1.2 cm, preferably between 0.7 and 1.1 cm, and preferably between 0.8 and 1.0 cm. The width of the false nail goes for example 0.7em. at 1.3cm.

Protection The device may comprise a peelable protective layer, or even several peelable layers. The device can still wear a non-peelable protective layer.

Makeup The subject of the invention is also a process for making up human keratin materials, for example nails, skin or lips, in which an electrochromic device according to the invention is applied to these materials. The keratinous materials receiving the device may be made up before the device is placed. Alternatively, the device as well as the keratin materials are covered with a makeup product after the application of the. device on keratin materials. The invention will be better understood on reading the detailed description which will follow, of examples of non-limiting implementation thereof, on examining the appended drawing, in which: FIGS. 1A and 1B are schematically two examples of electrochromic multilayer structures made in accordance with certain aspects of the invention with external power supply; FIG. 2 shows another example of an integrated power electrochromic multilayer structure; FIGS. 3A and 3B illustrate schematically, examples of attachment to the nail of an electrochromic multilayer structure, - Figure 4 illustrates the possibility of protecting the electrochromic multilayer structure with a protective layer, - Figures 5A to 5L illustrate different arrangements. possible, among others, within an electrochromic multilayer structure, FIGS. 6A to 6E show from very examples of electrochromic multilayer structures, FIGS. 7A-7J illustrate various examples of effects obtainable. FIG. 8 represents an example of a power supply device for electrically exciting an electrochromic multilayer structure and / or transmitting information to it. FIGS. 9A and 9B illustrate the use of the device of FIG. 8, FIG. in order to expose consumers to various multilayer electrochromic structures, FIG. 11 represents an example of a feed device according to an alternative embodiment of the invention; FIG. 1.2 represents a detail of FIG. 11, and FIG. a range of electrochromic multilayer structures, of different sizes. In the drawing, different layers in contact have sometimes been shown spaced apart for the sake of clarity. The constituent elements of the various illustrated devices have not always been represented with respect for the actual relative proportions, also for the sake of clarity of the drawing.

An electrochromic device 1 according to the invention may comprise, as illustrated in FIGS. 1A and 1B in particular, first 10 and second 20 active electrochromic layers, separated by an electrolyte layer 30, with which they come into contact. The device 1 may also comprise, as illustrated in FIGS. 1A and 1B in particular, first and second electrode layers 40 and 50, arranged on either side of the stack formed by the electrochromic active layers and the electrolyte layer and coming from in contact respectively with the first and second electrochromic active layers, on their side opposite to the electrolyte layer 30. The electrode layers 40 and 50 are for example coatings of a. transparent electrical conductive material, for example ITO, these coatings being supported by respective support layers 60 and 70, made for example in a transparent thermoplastic material, colored or otherwise, for example PET. The support layers 60 and 70 may each consist of a single flexible film or alternatively by assembling several films. soft rolled together. The flexible films may advantageously have a flexibility allowing them to be folded in half without breaking. The support layers 60 and 70 preferably have a thickness of less than 100 m, preferably less than 70 m. Thus, the electrochromic device may be capable, during application, of following the contours of the application zone, for example nails or lips. Thus, the electrochromic multilayer structure may be flexible enough to accommodate the curvature of the nail.

The thickness of the electrode layers, for example of the ITO coating mentioned above, may be between 50 and 1000 nm. The transparent electrically conductive material covers for example uniformly the support layers 60 and 70, but it may be different, for example to create patterns or allow selective excitation of certain areas of the structure. as will be explained below. Electrode layers can be made of other materials than ITO, for example gold and silver. Gold is the most efficient metal and also has many advantages (elasticity, electrochemical stability, ...).

It is possible to use, for the support layers, other materials than PET, for example polymethyl methacrylate (PMMA). The thickness of an electrochromic active layer 10 or 20 can be between 50 and 1000 nm. The thickness of the electrolyte layer 30 may be between 50 and 1000 nm.

The electrochromic multilayer structure 1 may be carried by a nail O, as illustrated. It can be fixed in various ways on the nail, as will be detailed later. The invention is however not limited to nail makeup. The stack of electrode layers, active electrochromic and electrolyte, is an electrosensitive stack, capable of changing appearance in response to electrical excitation. The electrical excitation of the multilayer electrochromic structure can be carried out temporarily, only to change the appearance of the multilayer electrochromic structure, or permanent, that is to say throughout the duration of use of the device, according to the multilayer structures used.

The electrochromic multilayer structure may retain its appearance once the electrical excitation ceases or may change in appearance once the electrical excitation ceases. One of the means for preserving this effect after electrical excitation is based on the use of electrolytic polymers of low conductivity thus slowing down the relaxation phenomenon of the electrochromic layers. It is thus possible to use conventional solid electrolytes based on polyethylene oxide (PEO) or on polypropylene. oxide (PPO) which have a relatively low conductivity (10 -5%). With this kind of material, only the amorphous phase provides conduction. If the glass transition temperature is changed by reducing the crystallinity index of the material, and also by using lower molecular weights. then in this case the conductivity of the solid electrolyte is increased (but with a loss of mechanical properties).

Different articles teach how to modulate the conductivity of solid electrolytes by incorporating plasticizers. In the article by P.M. Blonsky and DE Shriver. J. Am. Cheng. Soc. 1984.106, pages 6854-55, there is described a polymer of poly (bis (methoxyethoxy) phosphazene) which incorporates short PEO chains whose ionic conductivity at 25 ° C exceeds 1.0 5 S / cm. Bauer et al describe in US-A-4,654,279 a solid polymer electrolyte consisting of two interpenetrated phases: a crosslinked inert solid phase and a polymer liquid phase (low mass polyether) of good ionic conductivity (> 10-4 S1em). ). The relative proportions of the crosslinked phase and the liquid are chosen so as to combine the good mechanical and electrochemical properties. The ionic conductivity of this electrolyte is of the order of 10 -4 S / cm at room temperature. In U.S. Patent 4,792,504 to G. Schwab and M.T. Lee is disclosed a solid electrolyte whose matrix supporting the liquid phase is composed of PEO cross-linked by a polyacrylate compound. The liquid in which a metal salt is dissolved is a low molecular weight polyether or an aprotic solvent. The exemplary embodiments of FIGS. 1A and 1B are suitable for temporary electrical excitation, which can be done using electrical conductors 81 and 82, respectively connected to the electrode layers 50 and 40. The source of electrical energy is external to the device .

The electrical conductors 81 and 82 may pass through the different layers of the stack by being electrically isolated, when necessary, by respective insulating layers 84 and 85, for example in the form of an insulating sheath. In the example of FIG. 1A, the electrical conductors 81 and 82 are intended to contact a power supply by their lower ends, which lie in front of the nail O, on the lower face of the electrochromic multilayer structure 1. , the lower ends of the electrical conductors serving as contacts are little or not visible by the entourage of the person wearing the device, in many situations. The electrical conductors 81 and 82 may be made using metal conductor wires or strips, deposits of a metal, a polymer or an electroconductive ink, or, for example, by extensions of the electrode layers. The variant of the embodiment of FIG. 113 differs from that of FIG. 1A in that the electrical conductors 81 and 82 are formed, the conductor 81 being for example devoid of an insulating electrical sheath while the conductor 82 has an electrically insulating sheath. electrical insulator 84 which extends for example only on the side of the electrode layer 50, which offers the possibility of supplying the conductor 82 not only through the underside of the electrochromic device 1, but also by its distal end portion 88. In a variant, the conductor 82 has an electrically insulated lower end and can only be powered by its face opening on the wafer. distal end 88. FIG. 1B illustrates the possibility for the electrical conductors 81 and 82 to be made of conducting materials which extend to the respective electrochromic active layers 20 and 10. As mentioned above, the Electrochromic multilayer structure 1 may also include an integrated energy source, which may for example make it possible to subject it to a constant electrical voltage or to evolve in a predefined manner while it is being carried by the user, the voltage changing for example according to a program stored in a processor embedded by the multilayer electrochromic structure or depending on the state of an oscillating circuit, digital or analog, for example of multivibrator type, for example reference NE555D. The presence of an integrated power source also makes it possible to use an electrosensitive stack whose appearance change in response to an electrical excitation only exists as long as the electrical excitation lasts. In the example of FIG. 2, an integrated energy source 90 is connected to the electrode layers by electrical conductors, with the possible use of an electronic circuit 95, which may comprise or be constituted by a control member and / or setting, for example a potentiometer and / or a switch, which can be actuated by the user to modify at least one operating characteristic of the device, for example the starting or stopping of the device or an operating parameter such as for example a frequency of change of appearance and / or the amplitude of the excitation voltage of the multilayer structure. The switch and / or potentiometer can be accessible from the underside of the device, in front of the nail, or at its distal end.

Optionally, the device may be provided with an accessory for operating the control or adjustment member, within a single packaging device. The electrical circuit 95 may optionally integrate one or more sensors sensitive to an external stimulus, for example sensitive to light, moisture and / or temperature. For example, the color of the electrochromic multilayer structure may vary depending on the humidity of the temperature or the ambient light by means of an electronic circuit which modifies the excitation voltage of the electrochromic multilayer structure as a function of the output of a sensor of humidity, temperature or light. The energy source 90 is for example of the battery or capacitor type, and can be made by printing, if necessary. It is possible to use an electric power source of the paper stack type, for example a SOFT BATTERY reference, which makes it possible to generate a voltage of approximately 2.5 to 3 volts as a function of the surface, for a thickness of approximately 400 micrometers for example. Such a battery can use a paper-based electrolyte between an anode and a cathode, which are for example respectively aluminum or zinc on the one hand and magnesium oxide on the other hand. The on-board power source can still be of the type described in the articles Suga, T .; Konishi, H .; Nishide, H. "Photo-Crosslinked Nitroxide Polymer Cathode Leading Organic-Based Paper Battery", Chem. Commun., 2007, 1730-1732. or Suga, T .; Pu, Y.-J .; Kasatori, S .; Nishide, H. "Cathode- and Anode-Active Poly (Nitroxylstyrene) for Rechargeable Batteries: P- and N-Type Redox Switching via Substituent Effects", Macromolecules, 2007, 40, 3167-3173. Such a cell operates on a redox principle and may be in the form of a 200 nm thick rope. When the device comprises an on-board power source, the excitation voltage of the electrochromic multilayer structure may be constant or may vary in multiple ways in time, for example in square or in one or more ramps, for example triangular or sinusoidally. The excitation voltage can be substantially constant when the device is powered and decrease with the gradual depletion of the energy source. The on-board power source can also include a photovoltaic cell or a mechanism that draws energy from the user's movements.

The voltage applied to the electrosensitive stack may depend on a delay, intended for example to turn off the operation of the device after a predefined time, or may depend on at least one signal. from a stimulus-sensitive sensor, for example a light sensor, as mentioned above. Where appropriate, the device may comprise an electronic circuit configured to read information remotely, for example by means of one or more electrical contacts, or without contact, for example by means of an optical or radiofrequency link. This information makes it possible, for example, to program the operation of the device, for example the excitation level of the electrochromic multilayer structure and / or its variation over time.

The device may include an antenna capable of receiving electrical energy when subjected to a remote excitation field and / or receiving information, for example relating to an operating mode of the electrochromic multilayer structure. This antenna can be wound, printed or embedded in a chip integrated in the device. Such a chip may comprise, if necessary, an onboard battery or accumulator. In the example of Figure 2, the energy source is superimposed on the nail. In a variant not shown, the energy source is located in front of the nail, for example on the lower side of the device. This can reduce the thickness of the structure in its part superimposed on the nail. This may also make it possible, if necessary, to replace more easily the energy source when it is a miniature battery, for example of the button cell type. In the figures described below, the power supply conductors and / or the integrated energy source are no longer shown for the sake of clarity of the drawing. The electrochromic multilayer structure can be excited with electrode layers each at a substantially constant potential, with ohmic losses. This is particularly the case when the electrode layers are layers extending over the entire extent of the stack.

In a variant, the electrochromic multilayer structure comprises an electrode layer comprising at least two regions that can be selectively powered, for example at different potentials. This may allow for example to show or not a pattern according to the region or regions that are fed. For example, one of the electrode layers has two regions extending in a disjoint manner and respectively connected to two outputs of an electronic component for selectively powering them. Regardless of the arrangement of the electrosensitive stack, the attachment of the electrochromic multilayer structure to the keratin materials, for example nails, can be carried out in various ways. and preferably using a system allowing removal of the device without risk of damage. of it. The electrochromic device may comprise an adhesive covering the lower support layer, allowing the device to adhere when it is brought into contact with the application zone, for example the nails or the lips.

There is shown in Figure 3A, an adhesive layer 100, the adhesive is preferably hypoallergenic. When a repositionable adhesive is used to fix the electrochromic device on the keratin materials, this adhesive may comprise a block copolymer such as styrenic block copolymers available from the Kraton company, or an acrylic polymer with a molecular mass greater than 30000, better greater than 100000, preferably greater than 200000. This block copolymer or acrylic polymer may be present in the adhesive layer at a mass ratio greater than 20%, preferably greater than 30%, which may make it easier to obtain an adhesive layer. cohesive able to keep its integrity during the detachment.

The electrochromic device may comprise an adhesive layer crosslinkable to the application, with the advantage of promoting adhesion of the adhesive layer to the application area, especially the nails or the lips. Indeed, before crosslinking, the adhesive layer can develop good wettability on the application zone. After crosslinking, the adhesive layer has a greater hardness. and greater shear strength. When the electrochromic device comprises a crosslinkable adhesive, the electrochromic device may be provided in a sealed package, to prevent the crosslinking is initiated before use of the device. Preferably, the crosslinkable adhesive comprises a cyanoacrylate. The crosslinkable adhesive may comprise a mixture of ethyl cyanoacrylate, polymethyl methacrylate, and hydroquinone (adhesive available from Francenails).

The electrochromic device may comprise an adhesive layer comprising at least 5%, preferably at least 10% of at least one residual solvent. This feature has the advantage of promoting the adhesion of the adhesive layer on the application area, including nails or lips. Indeed, before total drying, the presence of residual solvent promotes the wettability of the adhesive layer on the application zone. After total drying, the adhesive layer has a greater hardness. and greater shear strength. The adhesive may comprise either a block copolymer such as styrenic block copolymers available from Kraton, or an acrylic polymer, or a BIO-PSA type silicone adhesive. For example, the adhesive is a solvent-phase acrylic adhesive, such as, for example, Duro-Tak adhesives available from National Adhesives, and having more than 10% residual solvent. The adhesive is preferably present on the multilayer structure before its installation, but alternatively it can be applied to the nail and the multilayer structure is brought into contact with it.

FIG. 3B shows a mechanical fastening system 110. When a mechanical fastening system 110 is used, it acts, for example, in the manner of a gripper, while being applied under the end of the nail, the latter then being pinched, for example, between the support layer 70 and a lug 111 of the fastening system 110. The attachment of the electrochromic multilayer structure can still be done differently, for example both by adhesion and pinching, by magnetization or electrostatic adhesion. In the following figures, the means used, for example an adhesive or a mechanical nail-tip fastening as described above, for fixing the electrochromic device on the lceratinic materials are no longer shown, for the sake of clarity of the drawing. .

The electrochromic multilayer structure I. may be externally coated, as illustrated in FIG. 4, with one or more external protective layers 120, which may or may not be peelable. At least one outer protective layer 120 may adhere due to electrostatic forces or through the use of an adhesive. If necessary, the device 1 comprises several peelable protective layers that can be successively removed, as soon as defects (scratches, wear) are observed. The presence of several peelable layers on the surface of the device allows, when. for example, there is a scratch on the surface of the device, to remove one of the layers on the surface. In addition, electrochromic devices are relatively expensive technological objects that need to be preserved, so that they can be reused several times if possible. Preferably, the peelable layers alternate layers of different chemistries, so that the layers have the characteristic of not adhering to each other. In other exemplary embodiments, a crosslinked topcoat is coated on the surface of the electrochromic device to improve its resistance. The crosslinking can be carried out either by reaction of an epoxide with an amine, or with cyanoacrylates, or by UV exposure of ethylenic double bonds. Preferably, the thickness of the top-coat layer is less than 50 m, preferably less than 20 m, better than 101.tm, so as to limit the impact of the top-coat on the flexibility of the device. Examples of crosslinked topcoats are given in US 2008/0031836. Various arrangements will now be described for obtaining various optical effects, allowing, for example, the production of patterns or gradients. It is possible, as illustrated in FIGS. 5A or 5B, to produce the first and / or second electrochromic active layers 10 or 20 with a non-uniform thickness, for example a thickness varying discontinuously, so that the appearance produced by the electrochromic structure depends on the presence or absence, at the level of the electrochromic active layer, of the material of this layer. For example, gaps 10a and / or 20a are made in the respective layers 10 and / or 20. The material of the layer 10 or 20 may be deposited in a pattern, by printing or transfer. As a variant, gaps 10a and / or 20a are produced by a material removal technique, for example by laser machining, etching or cutting. It is possible to use a deposited layer in the form of a pattern, for example in the form of a core, which, without electrical excitation, is not colored, and which, under electrical excitation, changes in color, for example to blue, which can show a violet heart pattern if the colored background is red. It can be seen in FIGS. 5A and 5E that the electrode layers may be present above the gaps 10A or 20A. It is also possible, as illustrated in FIG. 5C, to make both the first active layer 10 and the second active layer 20 each in a discontinuous manner, with, for example, the gaps I Oa and 20a of these active layers arranged vertically above them. each other.

The presence of the gaps IOa and / or 20a can make it possible to form one or more patterns that are visible only under certain conditions of electrical excitation of the electrochromic structure. For example, in the absence of electrical excitation of the electrochromic structure, the nail appears in a uniform color, as shown in FIG. 7A. This uniform color may be that of eg the nail or may result from the intrinsic coloration of one of the layers of the structure. It can also, as illustrated below, result from the present optically active layer within the electrosensitive stack or under it, for example as a colored background. In the presence of electrical excitation, a pattern M may appear on the dongle, for example in the form of a core, as illustrated in FIG. 7B, because of the change of appearance of the electrosensitive stack. Whether the electrode, active electrochromic and / or electrolyte layers are uniform or not, in particular of constant or non-constant thickness and / or of homogeneous or non-homogeneous composition, it is possible to interpose between one of the electrochromic active layers 10 or 20 and the electrolyte layer 30, a screen 160, for example an electrical insulator, for locally moving the electrolyte layer away from an adjacent electrochromic active layer, as illustrated in FIGS. 5D or 5E, or otherwise modifying the interaction between the electrolyte layers 30, layers located on either side of the screen 160 and to its contact. The shape given to the screen 160 depends on that of the pattern that is to be reproduced. The screen 160 is for example deposited by printing or transfer with the desired pattern 30. Screen 1.60 can be further machined, cut or engraved to form the desired pattern (s). The screen 160 may or may not be colored, reflecting or not, may be composed of polymethyl methacrylate (PMMA) or polyethylene terephthalate (PET).

The thickness of the screen 160 is for example between 1 and 100 microns, preferably between 5 and 30 microns. At least one of the layers of the stack of the multilayer structure may have inhomogeneous properties due to the use, within this layer, of materials having different electrical and / or optical properties. It is possible, as illustrated in FIG. 5F, to use for the electrolyte layer 30 different materials located in respective regions, which can be disjointed or not. For example, the small electrolyte layer 30 may comprise one or more first regions 30a having a first electrolyte and one or more second regions 30b having a second electrolyte, different from the first. The regions 30a and 30b are for example deposited by printing, or one of the regions is made by selectively treating the material of the other region, so as to transform this material and modify its properties. One of the regions 30a and 30b may have a shape corresponding to that of the pattern to be made. One of the regions 30a or 30b may be electrochemically inert and serve only to compensate for the thickness of the other region (s) acting as the electrolyte layer. At least one of the electrochromic active layers 10 or 20 can be made with a non-constant but non-zero thickness, as illustrated in FIGS. 5G, 5H and 51. The electrolyte layer 30 can also be made with a variation in thickness. , as in Figure 5.1. Such variation in thickness may for example be carried out gradually, with a constant decrease or not, to produce a gradient. The variation can be in one of the directions of a plane or alternatively in both directions. To obtain a variation in a first direction X of a plane, it is possible, for example, to use a spreader which moves in a second direction Y perpendicular to the first and whose slope in the first direction gives the variation of the thickness in this direction. direction. The thickness may also pass along at least one direction of the plane by an extremum, which may be a maximum. or a minimum. To compensate for the variation in thickness of one of the layers of the stack, at least one other layer of the structure may have a thickness that varies in the opposite direction. This other layer may be an adjacent layer. This other layer may be electrically active or not, and be optically active or not. In order to create an optical effect with the electrochromic active layer 10 and / or 20, several materials having different conductivities and / or electrochromic properties can be used, as illustrated in FIGS. 5L and 5K. FIG. 5L illustrates the possibility of producing the layer 20 with regions 20a and 20b formed by different materials. It is the same for the layer 10 of Figure 5K, formed of regions 10a and 10b of different materials. These different materials can be electrochromic but active. alternatively, only one of the materials plays this role, the other may be inert from the electrochromic point of view. The materials of the regions 20a and 20b can contact each other or not. The regions made with the electrochromic inert material can be used to compensate for the thickness of the other electrochromic active regions. In the case of a mixture of polymers, for example at one of the electrochromic active layers, two polymers can be used, being juxtaposed or mixed homogeneously or without the mixture leading to a homogeneous assembly. which makes it possible to form one or more patterns that will only be visible, for example, when the device is activated and / or to create other colors. When several polymers are juxtaposed, one can use polymers having different electrical conductivities, which can generate contrasts between the different regions. The electrochromic conductive polymer layer may comprise, for example, a material selected from polyaniline. polythiophene, and polypyrrole and a dopant. Preferably. the electrochromic conductive polymer layer comprises a material selected from polydiphenylamine, poly (4-amino biphenyl), poly (3-alkyl (C 1 -C 8) thiophenes), polydiphenyl benzidine), polyphenylene, polyphenylene vinylene ), a poly (allylene vinylene), a poly (aminoquinoline), poly (3,4-ethylenedioxythiophene) and its derivatives, or derivatives or copolymers thereof and a dopant.

All the examples of structures illustrated in FIGS. 5A to 5C can be combined with each other, in variants that are not illustrated.

The device 1 may be provided with at least one optically active layer 200. non-electrochromic, for example acting as a mask and / or filter vis-à-vis incident and / or reflected light, as illustrated in Figures 6A and 6B. or as a background; especially colored, as shown in Figure 6C. This layer 200 may be continuous, as shown in Figures 6f) and 6E, or discontinuous, as shown in Figures 6A and 6B. The layer 200 may in particular form a pattern. The electrochromic device may comprise at least one such optically active layer comprising an interference pigment. for example a nacre or a goniochromatic pigment, arranged in a uniform layer or not. for example in a pattern. As an illustration of nacres that can be introduced as interference pigment, mention may be made of gold-colored pearlescent agents marketed by Engelhard under the name Brillant Gold 212E (Timica), Gold 222C (Cloisonne), Sparkle gold (Timica) , Gold 4504 (Chromalite) and Monarch gold 233X (Cloisonne); bronze nacres sold especially by the company Merck under the name Bronze Fine (1.7384) (Colorona) and Bronze (17353) (Colorona) and by Engelhard under the name Super Bronze (Cloisonne); orange nacres sold especially by ENGELHAR.D under the name Orange 363C (Cloisonne) and Orange MCR 101 (Cosmica) and by MERCK under the name Passion orange (Colorona.) and Matte orange (17449) (Microna); brown-colored pearlescent agents marketed by Engelhard under the name Nu-antique copper 340XB (Cloisonne) and Brown CL4509 (Chromalite); nacres with a copper sheen sold especially by Engelhard under the name Copper 340A (Timica); the nacres with a red glint sold especially by MERCK under the name Sienna fine (17386) (Colorona); yellow-colored pearlescent agents marketed by ENGELHARD under the name Yellow (4502) (Chromalite); the red-colored pearlescent agents with a gold glint sold especially by ENGELHARD under the name Sunstone G012 (Gemtone); pink nacres sold especially by Engelhard under the name Tan opal G005 (Gemtone); black nacres with gold glare sold by the company ENGELHARD under the name Nu antique bronze 240 AB (Timica). blue nacres sold especially by the company MERCK under the name Matte Blue (17433) (Microna), silver-white mother-of-pearl sold in particular by the company Merck under the name Xirona Silver and gold-colored rosé orange nacres sold by the company MERCK under the name Indian sommer (Xirona) and mixtures thereof.

The electrochromic device may be arranged to change color when electrically excited, to filter at least one wavelength and thus to modify the color resulting from the superposition of the optically active layer comprising the interference pigment and at least one layer of stacking éleetrosensi.ble.

For example, the electrochromic device may be used to extinguish one or more colored components of at least one interference pigment exhibiting a color change as a function of the angle of observation and / or the curvature of the support. . .In that case. the electrically sensitive stack of the electrochromic device may have a color that filters one of the components of the color path of an underlying goniochromatic interference pigment. For example, if one considers a red-gold path, the electrochromic device can be arranged to have a blue color that will absorb the gold color. In this way, when the electrochromic device is activated, the perceived color will only be. red and when the electrosensitive stack becomes transparent, then the effect develops and the perceived color follows a red-gold path. The electrochromic device may also comprise a layer containing at least one diffractive pigment. The diffractive pigment used may in particular be chosen from those described in US patent application US 2003/0031870 published on February 13, 2003. A diffractive pigment may comprise, for example, the following structure: MgF 2 / Al / MgF 2, a diffractive pigment having this structure being marketed under the name SPECTRAFLAIR 1400 Pigment Silver by the company FLEX PRODUCTS, or SPECTRAFLAIR 1400 Pigment Silver FG. The proportion by weight of the MgF 2 can be between 80 and 95% of the total weight of the pigment. Other diffracting pigments are marketed under the names Metalure Prismatic by the company ECKART.

The electrosensitive stack can be used to filter on demand at least one wavelength of the light reflected by the underlying diffractive pigment. . The latter may have a goniochromatic effect, in particular a rainbow effect, which may be complete without activation of the electrochromic device and limited to a part of the visible spectrum when the electrochromic device is activated, by filtering one or more lengths of the electrochromic device. wave reflected by the diffractive pigment. An effect which is impossible to obtain in the prior art by a simple combination of interferential pigments is then obtained. The electrochromic device may comprise at least one luminescent compound 1.0, sensitive to at least one wavelength causing its luminescence. The electrosensitive stack of the electrochromic device can be used to filter the excitation wavelength (s) of the underlying phosphor, which is for example a fluorescent or phosphorescent compound. Thus, the electrochromic device can be used to allow or not the luminescence of the luminescent compound. For example, the electrochromic device may be used to filter the infrared or ultraviolet and the luminescent compound may be fluorescent in the infrared or ultraviolet. By more or less inhibiting the fluorescence depending on the state of excitation of the electrosensitive stack, the appearance of the luminescent compound can be modified. The device may comprise a fluorescent compound whose color is intensified by a light excitation, for example a red color. The electrosensitive stack can be used to filter locally or not the light activation of the fluorescent compound. Local inhibition of fluorescence may result in a difference in appearance between the areas of the compound whose fluorescence is inhibited and those in which it is not. For example, it is possible to obtain intense colored areas juxtaposed with paler colored areas, for example areas of intense red alternating with areas of a lighter red. The luminescent compound may be chosen from commercially available photoluminescent agents that may be suitable, for example the photoluminescent agent Luminux ™ marketed by HONEYWELL, in particular Luminux Effect Blue A, Luminux Effect Green A and Luminux Effect Red A. or the photoluminescent agent Netoje containing a high proportion of rare earths and marketed by Necitokin. In another example of implementation of the invention, at least one photoluminescent agent may comprise a semiconductor, in particular in partial form, for example Si, ZnO, CdSe, ... In an embodiment of According to the invention, at least one photoluminescent agent may comprise particles of average size ranging from about 10 nm to about 10 nm, for example in the form of CdSe crystals. CdSeIZnS or CdTe / CdS. Particles of PMMA, PE, PS or PC powder encapsulating CdSe nanoparticles are marketed by the company EVIDENT TECHNOLOGIES under the name EVI COMPOSITETM. The electrochromic device may comprise at least one metallic pigment. including a pigment to create highlight points on the makeup area. The color of the metal particles can be modulated by the electrosensitive stack, when the latter varies from transparent to colored or from one color to another, depending on its electrical excitation. The metal particles may be reflective, silvered, gold-plated or copper-plated and may be located, for example, in an optically active layer within the electrosensitive stack thereon or beneath it. The metal particles may be selected from. the reflective particles comprising a mineral substrate coated with a metal layer; mention may also be made of particles comprising a borosilicate substrate coated with silver. Particles with a platelet-shaped silver-coated glass substrate are sold under the name MI: CROGLASS METASHINE REFSX 2025 PS by the company TOYAL. Particles with a glass substrate coated with a nickel / chromium / molybdenum alloy are sold under the name CRYSTAL STAR GF 550, GF 2525 by the same company. The reflective particles with metallic reflection, whatever their shape, may also be chosen from particles with a synthetic substrate at least partially coated with at least one layer of at least one metal oxide, chosen for example from titanium oxides, in particular TiO2, iron including Fe2O3, tin, chromium, barium sulfate and the following materials: MgF2, CrF3, ZnS, ZnSe, SiO2, Al2O3, MgO, Y2O3, SeO3, SiO, HfO2, ZrO2, CeO2, Nb2O5, Ta2O5, MoS2 and mixtures thereof. By way of example of reflective particles, mention may be made, for example, of particles comprising a synthetic mica substrate coated with titanium dioxide, or particles of coated glass of brown iron oxide, of titanium oxide, of oxide tin or one of their mixtures such as those sold under the trademark REFLECKS by the company ENGELHARD. As other examples of reflective particles with a metallic sheen having on the surface a metal compound or including at least one coated metal compound, mention may be made of the particles proposed under the names METASHINE ME 2040 PS, METASHINE MCS090 PS or METASHINE MC280GP (2523) by the company NIPPON SHEET GLASS, SPHERICAL SILVER POWDER DC 100. SILVER FLAKE SV 6 or GOLD POWDER A1570 by ENGELHARD, STARLIGHT REFLECTIONS FXM by ENERGY STRATEGY ASSOCIATES 1NC, SILVERe SILVERe IE 0.008) (0.008 by MEADOWBROOK INVENTIONS, ULTRAMIN (ALUMINUM POWDER FINE LIVING), and COSMETIC METALLIC POWDER VISIONARY BRIGHT SILVER SEA, COSMETIC METALLIC POWDER VISIONAIRE NATURAL GOLD (60314) or COSMETIC METALLIC POWDER VISIONAIRE HONEY (60316) by ECKART The electrochromic device can be made to vary the contrast between at least one first colored region and a second surrounding region, whose color is for example a function of the activation state of the electrochromic device. Thus, by changing the color of the second region surrounding the first region, it is possible to increase or decrease the color contrast between the two, and for example to make the drawn pattern more or less visible, as illustrated in FIGS. 7C and 7D. In FIG. 7C, there is shown at least a first region R 1 whose color is predefined and at least one second region R 2 adjacent to the first region R 1, the color of which can change according to the activation state of the electro-bromic device. Thus, the color of the region R2 can pass from a color where the region Ri is clearly visible. as in FIG. 7C, to a state where the color of the region R 2 is close to the region R 1 and the region R 1 is hardly discernible due to lack of contrast. The region R2 corresponds for example, in the case of FIGS. 7C and 7D, to a background of uniform color, under the electrosensitive stack. Alternatively, the R2 region is defined as the surface layer.

In another variant. the region R2 is defined by a layer present in the electrosensitive stack.

The electrochromic device may comprise at least one so-called xchrome colonel agent, sensitive to an external stimulus, for example a photochromic, solvatochromic or tribochromic agent. In this case, a region comprising such a colonel agent may be of changing appearance depending on the environment of the masked zone but also on the state of the electrochromic device, which may be used to filter a color of the xchrome pigment and / or or as colonel environment of this colonel agent. When using at least one photochromic agent, the electrochromic device can be used to allow or not the excitation of the photochromic agent by the surrounding light. For example, if the photochromic agent changes appearance. following exposure to light of wavelength 500 nm, in particular its modified color, the electrosensitive stack may be arranged to filter at least one excitation wavelength of the photochromic agent. Thus, depending on the state of excitation of the electrochromic device, the photochromic agent may or may not react to the surrounding light. FIGS. 7E to 7H illustrate different cases of figures that can be obtained.

Figure 7E shows the appearance of masked areas without electrical excitation and Figure 7F with electrical excitation. Figure 7G illustrates the appearance of the masked area without light activation but electrical excitation and Figure 7H with light excitation and electrical activation. According to another aspect of the invention, the electrochromic device can be used to improve the visibility of a pearlscent or interference effect. For example, depending on a color of the electrosensitive stack of the electrochromic device and that of the interferential pigment or pigments, it is possible to amplify the perception of intensity of the color. For example, if the electrochromic device contains at least one nacre, for example in one of the layers of the stack or on its surface, for example a nacre of red color, and that the electrochromic device allows a change in color from the electrosensitive stack of blue to green, the intensity of the color of the mother-of-pearl will be perceived as more intense with the electrosensitive stack of green color. When stacking. Electrosensitive electrochromic device is made to be able to take a color that is close to that of an area present on its surface or within the stack, the visibility of this area can be decreased. If said zone has a goniochromatic effect according to a color path and if the electrochromic device can present, by activation, one of the colors included in the color path, it is possible then to mask the presence of this zone or not according to the angle of observation, illumination and / or curvature of the object. For example, one can more or less reveal the color path of a goniochromatic pigment on demand, for example to increase or not a volume effect. The electrochromic device can be used to selectively enhance the color effect of a pearlescent pigment, for example a mother-of-pearl. Depending on the color of the electrochromic device, it is possible for example to amplify or not the intensity of highlight points made with such a nacre.

The electrosensitive stack may be used to absorb or reflect the light transmitted by an optically active layer deposited on the surface of the electro-ochroanic device, this layer containing an interference pigment, for example a mother-of-pearl giving an iridescent effect, or a liquid crystal, the gold-colored mother-of-pearls sold by ENGELHARD under the name Brillant gold 20 212G (Timica), Gold 222C (Cloisonne), Sparkle gold (Timica), Gold 4504 (Chromalite) and Monarch gold 233X (Cloisonne); bronze nacres sold especially by the company Merck under the name Bronze Fine (17384) (Colorona) and Bronze (17353) (Colorona) and by Engelhard under the name Super Bronze (Cloisonne); orange nacres sold especially by the company Engelhard under the name Orange 363C (Cloisonne) and Orange MCR 101 (Cosmica) and by the company Merck under the name Passion Orange (Colorona) and Matte Orange (17449) (Microna); the nacres of brown hue sold especially by Engelhard under the name Nu-antique copper 340XB (Cloisonne) and Brown C1.14509 (Chromalite); nacres with a copper sheen sold especially by Engelhard under the name Copper 340A (Timica); the nacres with a red glint sold especially by MERCK under the name Sienna fine (17386) (Colorona); yellow-colored pearlescent agents marketed by ENGELHARD under the name Yellow (4502) (Chromalite); the red-colored pearlescent agents with a gold glint sold especially by ENGELHARD under the name Sunstone G012 (Gemtone); pink nacres sold especially by Engelhard under the name Tan opal G005 (Gemtone); the black nacres with gold reflection sold by the company ENGELHARD under the name Nu antique bronze 240 AB (Timica), the blue nacres sold especially by MERCK under the name Mate blue (17433) (Microna), the white nacres with reflection silver sold in particular by the company Merck under the name Xirona Silver and the golden-green orange-colored mother-of-pearl marketed by Merck under the name Indian summer (Xirona) and their mixtures. Interferential pigments having magnetic properties are for example those marketed under the trade names COLORONA BLACKSTAR BLUE. COLORONA BLACKSTAR GREEN_ COLORONA BI .., ACKSTAR GOLD, COLORONA BLACKSTAR RED, CLOISONNE NU ANTIQUE SUPER GREEN, MICRONA MATTE BLACK (17437), MICA BLACK (17260), COLORONA PATINA SILVER (17289) and COLORONA PATINA GOLD (117288) of the company MERCK or even FLAMENCO TWILIGHT RED, FLAMENCO 25 TWILIGHT GREEN. FLAMENCO TWILIGHT GOLF. FLAMENCO TWILIGHT BLUE, TIMICA NU ANTIQUE SILVER 110 AB, TIMICA NU ANTIQUE GOLD 212 GB, TIMICA NU-ANTIQUE COPPER 340 AB, TIMICA NU ANTIQUE BRONZE 240 AB, CLOISONNE NU ANTIQUE GREEN 828 CB, CLOISONNE NU ANTIQUE BLUE 626 CB, GEMTONE MOONSTONE G 004, CLOISONNE NU ANTIQUE RED 424 CB, CHROMA-LITE BLACK (4498), CLOISONNE NU ANTIQUE RED FLAMBE (code 440 XB). CLOISONNE NU ANTIQUE BRONZE (240 XB), CLOISONNE NU ANTIQUE GOLD (222 CB) and CLOISONNE NU ANTIQUE COPPER (340 XB) of the company ENGELHARD. The electrosensitive stack may, for example, exhibit a light-dark variation as a function of the electrical excitation. Thus, when the electrosensitive stack gives a light color, the interference pigment located above this electrosensitive stack is not very visible. On the other hand. when the electrosensitive stack or the liquid crystal is dark, the interference pigment or the liquid crystal becomes clearly visible. Figures 71 and 7J illustrate the case where an interference pigment is more or less apparent depending on the color of the background. FIG. 71 shows the case where the background color is dark, for example when the electrochromic device is not activated and FIG. 7J the case where the background color is clear, for example when the electrochromic device is activated.

FIG. 8 shows a device 300 that can be used to electrically power an example of an electrochromic device 1 according to the invention, when the latter does not comprise an integrated energy source or when the latter requires recharging and / or the programmed device.

The device 300 may comprise a housing 301 for receiving at least one finger, this housing 301 being able to be provided with electrical contacts 302 and 303 intended for example to electrically power the electrochromic device. The electrical contacts 302 and 303 can be fixed or spring-mounted so as to adapt more easily to the finger.

In a variant not shown, the device 300 comprises a radio frequency device for transmitting by induction of energy and / or information to an antenna integrated in the electrochromic device. To use the device 300 of Figure 8, the user can engage his finger in the housing 301, as shown in Figures 9A and 9B, and bring the electrical contacts of the electrochromic device, for example formed by the electrical conductors 81 and 82 shown FIGS. 1A and 1B, resting on the supply terminals 303 and 302. A supply device such as, for example, the device 300, can be offered for sale with the electrochromic devices in the same package. The sale of articles having a result evolution following a stimulus, as is the case of an electrochromic device produced according to the invention, may have the disadvantage that during the act of purchase the consumer is not able to visualize the result, which can be a reluctance to purchase. To remedy this, a display can be present at the point of sale with at least one tester allowing the consumer himself to apply the electrical stimulation and thus control the color change. This display can include different means of electrical excitation. FIG. 10 shows an exemplary display 400 that can be used to present consumers with one or more electrochromic multilayer structures according to the invention.

This display can include means for selectively supplying one or more electrochromic structures, in order to allow an observer to perceive a change induced by a modification of the electrical excitation of at least one of the electrochromic structures. This supply means is for example in the form of a stylet 410 or other handpiece, that the user can use to electrically power the multilayer electrochromic structure of his choice. The display can include, if necessary, several feeding means 410, to allow its use by several people simultaneously. The electrochromic structures present on the display can be associated with identifiers allowing the consumer to obtain, subsequently, a package containing the corresponding electrochromic structure. The display can also include an electrochromic multilayer structure excited automatically or when an observer acts on a control member, to observe the effect of change of appearance. The electrochromic multilayer structure may be a structure identical to those proposed for sale or a larger size structure, more easily visible from a distance. The user can, if appropriate, offer a range of electrochromic multilayer structures, as shown in Figure 13, for example of different sizes, in order to adapt to different fingers. A sizing help system can be made available to users. This help system of choice may include a panel showing drawings, diagrams or photographs of fingers. Simply place your finger on the panel, and visualize the drawing, the diagram, or the photograph of finger or nail corresponding best to your own finger or nail. A reference corresponding to the selected finger or nail size makes it possible to choose the size of the most appropriate electrochromic device. Preferably, at least eight or ten different electrochromic nail sizes are available to users.

The electrochromic devices can be in the form of false nails, which can be offered to users by packets of electrochromic false nails (for both hands), with for example among these false nails 2 copies of width between 1.1cm and 1.3cm , preferably 2 copies 1.2cm wide (for inches). 2 copies of width between 0.6cm and 0.8cm, preferably 2 copies of width 0.7cm (for the ears), and 6 copies of width between 0.8cm and 1.0cm, preferably 6 copies of width 0.9cm (for the other fingers ). False nails can also be offered to individual users.

The electrochromic device (s) may be sold in at least one at least partially transparent package for displaying a change of appearance of the electrochromic device related to a change in the excitation thereof. The electrical contacts of the electrochromic device (s) can be connected to a battery contained in the package with an electrical circuit comprising a switch accessible by the user without opening the package. The switch can allow to pass the electric current for example under the effect of a pressure exerted by the user at a predefined location of the package. The supply of the electrochromic multilayer structure, to recharge an integrated power source or to excite the electrosensitive stack in order to change its appearance at least temporarily, can be done using a feed device such as the one shown FIGS. 11 and 12. This device comprises, for example, a handpiece that can be manipulated by the user, provided at the end of two electrical terminals 420 and 421, making it possible to electrically contact two corresponding contacts of the electrochromic multilayer structure, for example located at the distal end thereof or on a lower face thereof. The device 415 can accommodate, if necessary, an electrical power source 423. The device 415 may comprise an activation button 424 and a switch 426 for connecting or not at least one of the terminals 420 or 421 at the source of energy 423. Thus. the user can use the device 415 by bringing it into contact with the electrochromic multilayer structure to be excited, and then use the activation button 424 to precisely control the duration during which a voltage is applied. When the change of appearance is progressive, the user can stop applying the voltage when the desired appearance is reached. The invention is not limited to an electrochromic device intended to be applied to the nail and the electrochromic device may for example be applied to the lips or the skin, for example by the use of a hypoallergenic adhesive. The particularities of embodiment of the various examples illustrated can be combined within variations not shown. For example, the electrical lead arrangements shown in Figs. 1A and 1B are for the electrochromic multilayer structures shown in Figs. 3A through 6E, among others. It is the same for the arrangement shown in Figure 2 and for the fixing means on the keratin materials described with reference to Figures 3A and 3B. The peelable protective film illustrated in Figure 4 may be added to any of the stacks described in Figures 5A to 51 and bA to 6E, among other embodiments. The patterns made with the electrochromic multilayer structure may be various, especially correspond to any alphanumeric and / or degraded character, especially any drawing incorporating a gradient. The pattern may optionally be personalized, the person intended to receive the device providing an image of the pattern of his choice and the electrochromic multilayer structure being made accordingly. The invention is not limited to electrochromic multilayer structures in which the electrochromic layers and electrochromic active layers are distinct and these layers can be confused, if appropriate, as illustrated in the publication WO 2005/015301.

The pattern (s) may be visible only upon excitation of the electrochromic device or, alternatively, cease to be visible only upon excitation of the electrochromic device, depending on the materials used. The electrochromic active layers may comprise one or more polymers chosen, for example, from the following list, alone, or mixed or juxtaposed: poly (3-methyl-thiofen): poly (3,3-dimethyl-3,4) 2-dihydro-2H-thieno- [3,4-b] dioxepine: poly (3,4-ethylenedioxypyrrole) (a) and poly (3,4-propylenedioxypyrrole) (Pprodop) (b) [representative of PXDOT (poly ( 3,4-alkylenedioxypyrrole): (a) poly (N-sulfonatopropoxy-ProDOP): (b) [poly (bis-ethylendi.oxypyrrole-N-methylcarbazole)]: Poly (bis-ethylend.ioxypyrrole-pyridine): Poly (Bis-ethylendioxypyrrole-pyridopyrazine): Poly (benzo [c] thiophene-N-2-ethylhexyl-4,5-dicarboxylic imide): Poly (2,2 '- [10-methyl-3,7-phenothiazene] -6 , 6'-bis [4-phenylquinoline): The electrolyte layer may comprise one or more polymers selected, for example, from the following list: alone, in a mixture, or in a juxtaposed way: According to the invention, the polymer layer electrochromic driver can understand by exe A material selected from polyaniline, polythiophene, and polypyrrole and a dopant. Preferably, the electrochromic conductive polymer layer comprises a material selected from polydiphenylamine, poly (4-aminobiphenyl), poly ( 3-alkyl (C 1 -C 8) thiophenes), polydiphenyl benzidine), polyphenylene, poly (phenylene vinylene), poly (allylene vinylene), poly (aminoquinoline), poly (3,4-ethylenedioxythiophene) and its derivatives, or derivatives or copolymers thereof and a dopant. EXAMPLES EXAMPLES Example 1 On a support and electrode layer available from Shieldal (USA), formed of polyethylene terephthalate (PET) coated with transparent conductive oxide ITO (indium Tin Oxide), for example 3 cm. A polyethylene dioxythiophene solution (commercially available under the name Baytron and available from Bayer) is deposited and then dried to form a first electrochromic active layer.

A polypyrrole film is then deposited by electrophoresis on a second layer of polyethylene terephthalate coated with transparent oxide electrically conductive. Electropolymerization is performed with an aqueous solution containing lithium perchlorate using a constant potential of 0.7V. A second electrode support layer coated with a second electrochromic active layer is obtained. The electrolyte is produced by dissolving 0.015 g of lithium perchlorate in a mixture of 0.7 g of oxyethylene and epichloridin copolymer (available from DAISO). Co. under the reference EM-2), and 5mL of tetrahydrofuran. This mixture is then coated on the Baytron coated electrode. After 2 hours of drying at room temperature, the counter-electrode coated with polypyrrole is added, exerting pressure to obtain the electrosensitive stack. The latter shows a color change between yellow and dark blue, when the applied potential varies between -1.5V and + 1.5V. This color change is produced in less than 10 seconds. The maximum change in transmittance of the stack obtained is between 45% and 70%. The multilayer structure is applied to a false nail. The layers of Baytron and polypyrrole are connected to. electrical conductors located on the underside of the false nail and the end of the false nail, so as to remain accessible, without, after application, degrade the aesthetics of the device. The electrical conductors are copper plates with a surface area of 1 mm 2 each. Example 2 This example differs from Example 1 in that the first electrochromic active layer is coated so as to form a pattern, for example in the form of a heart. The electrical excitation of the device makes it possible to modify its color, as illustrated in FIGS. 7A and 7B. EXAMPLE 3 This example differs from Example 1 in that an opaque film forming a cover, for example of red color, is cut off on the surface of the electrosensitive stack, so that it leads to the visualization of the electrosensitive stack. a pattern, for example a star. The electrical excitation makes it possible to modify the color of the pattern delimited by the cutting of the cache. Example 4 This example differs from Example 1 in that the Baytron layer is non-uniformly deposited. The spreader is set to have two sides at different heights. You can get a color gradient, which shows a color change between a yellow gradient and a blue gradient, by changing the potential between -1.5 V and 1.5 V.

Example 5 This example differs from Example 1 in that the electrosensitive stack covers an optically active layer consisting of a red color film. A color change of the device between orange-brown and blue-violet can be observed, changing the potential between -1.5 V and -F. 1.5 V.

EXAMPLE 6 This embodiment differs from Example 1 in that it comprises five alternating layers of 5 μm thick cellulose acetate butyrate and 511 μm thick polyethylene deposited on the surface of the upper support layer. to form peelable protective films. To facilitate the separation of each layer, a portion of the cellulose acetobutyrate coating slightly exceeds the application area, so that the upper layer has a tab to easily apprehend the film to peel, without to remove all the layers.

Example 7 The electrochromic device has in this example, on its surface, a protective layer that can be removed by removing make-up. The rest of the device is resistant to make-up removal.

The device according to Example 1 is topcoated with a layer of ethanol-based varnish (20% shellac gum, 80% ethanol). PET being ethanol resistant, it is possible to remove the protective layer with an ethanol-based makeup remover without damaging the device. It is then possible, if necessary, to reapply a protective layer using the varnish.

Example 8 An adhesive coated with a 50 μm layer of Dispofix 645 E (available from National Adhesives) is brought into contact with the underside of the electrochromic device of Example 1. Pressure is exerted to promote the accession. A protective film of the adhesive is removed at the time of application.

EXAMPLE 9 To the optically active layer of Example 1 was added 3% of the Xirona Kiwi-pink goniochromatic pigment (Merck). In this way, the increased electrochromic effect of the optical effect of the goniochromatic pigment will be more or less visible depending on the state of excitation of the electrochromic device.

EXAMPLE 10 To the optically active layer provided by Example 1 is added 3% of Metashine Silver pigment (Nippon Sheet Glass Company). In this way, the increased electrochromic effect of the optical effect of the metallic pigment will be more or less colored depending on the state of excitation of the electrochromic device.

The invention is not limited to the illustrated examples. The electrochromic device may be non-emissive or emissive. The expression "having a" shall be understood as being synonymous with "having at least one" unless the contrary is specified.

Claims (11)

REVENDICATIONS1. Electrochromic device (1) to be applied to the nail, comprising an electrochromic multilayer structure and electrical contacts, at least one (81) of said contacts being disposed on a distal portion of the device, extending in front of the nail . 2. Device according to claim 1, at least one of said contacts (81) being disposed on a lower face of the device. 3. Device according to claim 1 or 2, at least one (88) of the contacts 10 being disposed on a slice of the device, at its distal end. 4. Device according to any one of claims 1 to 3. at least one (88) contacts extending over a height greater than the thickness of an electrode layer of the electrochromic multilayer structure. 5. Device according to any one of claims 1 to 4, one (81) of the 15 contacts being disposed on a lower face of the device and the other (88) on its edge, at its distal end. 6. Device according to any one of claims 1 to 5, comprising an electrosensitive stack comprising electrochromic active layers (10, 20), electrode layers (40. 50) and an electrolyte layer (30). 20 7. Device according to any one of claims 1 to 6, comprising at least one electrical component (95) electrically connected to at least one of said contacts. 8. Device according to claim 6, said contacts being connected to the respective electrode layers. Apparatus according to any one of the preceding claims, having an integrated power source. 10. An assembly comprising an electrochemical device as defined in any one of the preceding claims and a supply device comprising two terminals intended to electrically contact said contacts. 11. The assembly of claim 10, the terminals being disposed in a housing for receiving a finger.