FR2947430A1 - Cosmetic device i.e. finger nail polish, for nails, has electrochromic multi-layer structure located below active layer, where structure includes electrosensitive stack formed of electrode layers, electrochrome layers and electrolyte layer - Google Patents

Abstract

The device has an optically active layer (200) including an interferential pigment or a liquid crystal, and an electrochromic multilayer structure (1) located below the optically active layer. The electrochromic structure occupies a dark state and clear or transparent states according to electric excitation. The optically active layer entirely covers the electrochromic structure. The electrochromic structure includes an electrosensitive stack formed of electrode layers (40, 50), active electrochrome layers (10, 20), and an electrolyte layer (30). An independent claim is also included for a method for make-up of human keratinous materials.

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 to remake 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. it is necessary to remove all makeup then to make up again with another makeup product. It is known from application FR 2 811 206 to apply to 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. In particular, there is a need to benefit from production and cost devices compatible with large-scale marketing, easy to use and to set up, capable of changing in situ appearance and / or of being brought into the 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 Electrochr omism in Polymers: Structures and Devices and Combined Electrochromic and Plasmonic Opticai Responses in Conducting Polymer / Metai Nanoparticle Films, New Materials Departrnent, CIDETEC-Center for Electrochemical Technologies, San Sebastian Technological Park , Paseo Miramon 196, E-20009 Donastia-San Sebastian, Spain, disclose other possible arrangements of electrochromic structures. The invention aims to propose new makeup devices for producing new makeup effects. The object of the invention is, according to one of its aspects, a cosmetic device to be applied to human keratin materials, comprising: an optically active layer comprising an interference pigment or a liquid crystal, an electrochromic multilayer structure located under the layer optically active. The electrochromic multilayer structure may comprise an electrosensitive stack, homogeneous or not, of at least: first and second electrode layers, first and second active electrochromic layers, an electrolyte layer between the electrochromic active layers. In general, the electrode layers may or may not be electrochromic active layers. The electrochromic multilayer structure can act as a background of variable color or opacity, making it possible to make the optically active layer covering it more or less visible. The electrochromic multilayer structure may, 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, while 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. The device can be configured to attach to a fingernail, and apply to a nail already made up or not, or even on a false nail.

Non-homogeneous multilayer structure The electrochromic multilayer structure may comprise a non-homogeneous electrosensitive stack of at least: the first and second electrode layers. the first and second active electrochromic layers, the electrolyte layer between the electrochromic active layers. By "non-homogeneous" it should be understood that in at least two locations of the electrosensitive stack, while it 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 being able to vary in a continuous manner. or discrete, and can be locally zero. 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 that are interesting in cosmetics, for example at least one gradient or a decorative pattern, especially 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, which is not zero, and a region having a 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 stacking. The thickness is measured according to a dimension Z, locally perpendicular to X and Y. The thickness of at least one layer may vary progressively 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, may have both regions having a non-zero thickness and regions having a zero thickness. 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. At the same time, 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. 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 may 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 structure can include at least one cache allowing the formation of at least one pattern 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 may form at least one pattern, the visibility of which may depend on the state of excitation 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 color close. 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 cache 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. If necessary, the printing of the cache is performed on a removable film, to remove the cache to replace 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 metal layer, a polymer film, and may optionally include a microrelief intended for example to create optical effects.

The thickness of the cover is for example between 1 and 100 microns, preferably between S and 30 microns. When the cache is not completely opaque, the cache can act as an optical filter, for example to control the light reaching underlying layers. Electrical contacts The device may comprise electrical contacts, at least one of said contacts being disposed on a distal portion 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. The multilayer structure may comprise an electrosensitive stack as defined above, homogeneous or not, and may or may not be provided with a cache as defined above. 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 electrochromic active 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. electrosensitive stack.

Electrochromic device with other optically active layer The device may comprise another optically active layer superimposed at least partially on the electrosensitive stack. This other optically active layer is for example located above the electrosensitive stack. It may, alternatively, be located between two layers of the electrosensitive stack or be located under the electrosensitive stack. The additional optically active layer can be formed of a cache as defined above, it can be colored or not, and be useful to change the appearance of the device. The additional 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 additional optically active layer may extend over the whole extent of the electrosensitive stack or be discontinuous, and for example form at least one unit. The thickness of the additional optically active layer is, for example, between 1 and 100 microns. preferably between 5 and 30 microns.

It may, if necessary, be deposited by the user on the surface of the multilayer structure, or be deposited by printing with a particular pattern if necessary. The optically active layer may be deposited, for example, on a removable protective layer of the multilayer structure.

The additional 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 comprising the interference pigment or the liquid crystal or the other optically active layer mentioned above 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. The optically active layer may be located above the electrosensitive stack and 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. In exemplary embodiments, the electrosensitive stack may take, depending on its electrical excitation, substantially the same color as the optically active layer. This may 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.

Built-in power source The device can have an integrated power source. The energy source may comprise a battery, an electric accumulator. a capacitor and / or a coil. The energy source can be flexible or rigid. 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 may comprise at least first and second materials, in particular polymers. These polymers may be chosen from electrochromic polymers. The first and second materials can 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 can 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 1.1em, and preferably between 0.8 and 1.0 cm. The width of the false nail ranges from 0.7 cm to 1.3 cm. Protection The device may comprise a peelable protective layer, or even several peelable layers. The device can still wear a non-peelable protective layer. The invention further relates to a process for making up human keratin materials, for example the nails, the skin or the lips, in which an electrochromic device is applied to these materials, produced according to at least one of the aspects of the invention. invention defined above. The keratinous materials receiving the device may be made up before the device is placed. In a variant, the device as well as the keratin materials are covered with a makeup product after the device has been placed on the keratin materials.

The invention will be better understood on reading the following detailed description of examples of non-limiting implementation thereof, on examining the appended drawing, in which: FIGS. 1A and 1B show, schematically, two examples of electrochromic multilayer structures made in accordance with certain aspects of the invention, with an external power supply; FIG. 2 represents 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, FIG. 4 illustrates the possibility of protecting the electrochromic multilayer structure with a protective layer; FIGS. 5A to SL illustrate various possible arrangements, among others, within an electrochromic multilayer structure, FIGS. 6A to 6E show other examples of electrochromic multilayer structures, FIGS. 7A to 7J illustrate various examples of effects that can be obtained, FIG. 8 represents an example of a supply device for electrically exciting and / or transmitting information to an electrochromic multilayer structure, FIGS. 9A and 9B illustrate the use of the device of FIG. 8, FIG. 10 represents an example of a display for exposing consumers to different multilayer electrochromic structures; FIG. 11 represents an example of a feed device according to a variant of FIG. FIG. 12 shows a detail of FIG. 11, and FIG. 13 represents 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. 1.A and IB 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. disposed on either side of the stack formed by the electrochromic active layers and the electrolyte layer and contacting respectively the first and second active electrochromic layers, on their face opposite to the electrolyte layer 30. The electrode layers 40 and 50 are, for example, coatings of a transparent electrically 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 not, for example PET. The support layers 60 and 70 may each consist of a single flexible film or alternatively by assembling a plurality of flexible films laminated 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 μm, preferably less than 70 μm. 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 multilayer structure also comprises an optically active layer 200, situated above the electrosensitive stack, as will be explained later in the description of FIGS. 6A. at 6E. In Figs. 1A-5L, the optically active layer 200 has been shown with a particular positioning example, but this positioning may be modified to any of those of Figs. 6A-6E. The optically active layer has sometimes been shown with openings, other times without openings. An example with openings can be replaced by an example without openings. The optically active layer 200 contains an interference pigment or a liquid crystal, as will be explained below. 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, e ..). Other materials may be used to make the support layers, such as PET, for example polymethyl methacrylate (PMMA). The thickness of an electrochromic active layer 10 or 20 may be between 50 and 1000 nm. the electrolyte layer 30 may be between 50 and 1000 nm. The electrochromic multilayer structure 1 may be carried by a nail 0, 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 electrochromic multilayer structure can be carried out temporarily, only to change the appearance of the multilayer electrochromic structure, or permanent, that is to say during the entire duration of use of the device, according to the multilayer structures used. The electrochromic multilayer structure may retain its appearance once electrical excitation ceases or may change in appearance once electrical excitation ceases. One of the means for preserving this effect after electrical excitation is based on the use of electrolyte 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 else polypropylene oxide (PPO) which have a relatively low conductivity (10 -5 S / cm). 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 admittedly 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. Blonslky and Dl. Shriver, J. Am. Chem. Soc. 1984A06, pages 6854-55, there is disclosed a poly (bis (methoxyethoxy) phosphazene) polymer which incorporates short chains of PRO whose ionic conductivity at 25 ° C exceeds 10 "1cm.

Bauer et al describe in US Pat. No. 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 S / raw). 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 Scm at room temperature. In U.S. Patent 4,792,504 to O. Schwab and Mi. Lee is disclosed a solid electrolyte whose matrix supporting the liquid phase consists of PEO crosslinked with a polyacrylate type 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. Thus, 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 can be made using metal conductor wires or strips, deposits of a metal, a polymer or an electroconductive ink, or otherwise, for example by extensions of the layers. electrodes out of the electrosensitive stack. The variant of the embodiment of FIG. 1B differs from that of FIG. 1A in that the electrical conductors 81 and 82 are formed, the conductor 81 being for example devoid of insulating electrical sheath while the conductor 82 comprises an electrical insulator 84 which is extends for example only on the side of the electrode layer 50, which offers the possibility of supplying the conductor 82 not only by the lower face of the electrochromic device 1, but also by its distal end portion 88. In a variant, the S conductor 82 has an electrically insulated lower end and can be powered only by its face opening on the distal end portion 88. FIG. 1B illustrates the possibility for electrical conductors 81 and 82 to be made with conductive materials extending to the respective electrochromic active layers 20 and 10. As discussed above, the electrochemical multilayer structure romique 1 may also include an integrated power source, which may allow for example to subject it to a constant voltage or evolving in a predefined manner while it is worn by the user, the voltage evolving for example according to a program stored in an embedded processor by the electrochromic or state-dependent multilayer structure of an oscillating circuit, digital or analog, for example of the multivibrator type, for example of reference N, 555D. 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 power source 90 is connected to the electrode layers 40 and 50 by electrical conductors 91 and 92, with possibly. as illustrated, use of an electronic circuit 95, which may comprise or be constituted by a control member and / or setting 97, for example a potentiometer and / or a switch, which can be actuated by the user to modify at least one The 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 structure multilayer. The switch and / or potentiometer can be accessible from the bottom face 30 of the device; in front of the nail. or at its distal end.

Spain, disclose other possible arrangements of electrochromic structures. The invention aims to propose new makeup devices for producing new makeup effects. The object of the invention is, according to one of its aspects, a cosmetic device to be applied to human keratin materials, comprising: an optically active layer comprising an interference pigment or a liquid crystal, an electrochromic multilayer structure located under the layer optically active. The electrochromic multilayer structure may comprise an electrosensitive stack, homogeneous or not, of at least: first and second electrode layers, first and second active electrochromic layers, an electrolyte layer between the electrochromic active layers. In general, the electrode layers may or may not be electrochromic active layers. The electrochromic multilayer structure can act as a background of variable color or opacity, making it possible to make the optically active layer covering it more or less visible. The electrochromic multilayer structure may, 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, while 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. The device can be configured to attach to a fingernail, and apply to a nail already made up or not, or even on a false nail.

The voltage applied to the electrosensitive stack may depend on a delay, intended for example to extinguish the operation of the device after a predefined period of time, or may depend on at least one signal coming 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 an electronic chip integrated in the device. Such a chip may comprise, if necessary, a battery or an accumulator embedded 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 overlapping portion of 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 may be excited with electrode layers each at a substantially constant potential, with near 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 ceratinic materials, for example the nails, can be carried out in a variety of ways, and preferably by means of a system allowing the removal of the device without risk of damaging 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. FIGS. 2 and 3A show an adhesive layer 100, the adhesive preferably being hypoallergenic. When a repositionable adhesive is used to fix the electrochromic device on the keratinous 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, in particular 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 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 cyanoacryate. 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 copopolymer such as the styrenic block copolymers available from Kraton, or an acrylic polymer, or a BI0.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 attachment at the end of the nail as described above, for fixing the electrochromic device on the keratin materials are no longer shown, for the sake of clarity of the drawing. . The electrochromic multilayer structure 1 may be coated externally, as illustrated in FIG. 4, with one or more external protective layers 120, which may or may not be peelable.

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 humidity, temperature or light sensor. 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 cell may use a paper-based electrolyte between an anode and a cathode, which for example are 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 to an 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 battery operates on a redox principle and can be in the form of a film of 200 nm thick. When the device comprises an onboard 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 still sinusoidally. The excitation voltage may still be substantially constant when the device is energized and decrease with the gradual depletion of the power source. The on-board power source can also include a photovoltaic cell or a mechanism that draws energy from the user's movements.

FIGS. 5A and 5B show that the electrode layers may be present above the gaps 10A or 20A. It is also possible, as illustrated in FIG. SC, to carry out both the first active layer 10 and the second active layer 20 each in a discontinuous manner, with, for example, the gaps 10a and 20a of these active layers arranged one above the other. others. The presence of the gaps 10a and / or 20a can make it possible to form one or more patterns which 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 of uniform color as shown in FIG. 7A. This uniform color may be that of the nail, for example, or may result from the intrinsic coloration of one of the layers of the structure. It may further, as illustrated below, result from the presence of an 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 nail, for example in the form of a heart, 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 shown 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 on 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. The screen 160 can still be machined, cut or etched to form the desired pattern or patterns. 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. As can be seen in FIG. 5F, use for the electrolyte layer 30 S different materials located in respective regions, which can be disjointed or not. For example, the electrolyte layer 30 may comprise one or more first regions 30a comprising a first electrolyte and one or more second regions 30b comprising 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 produced. One of regions 30a or 30b may be electrochemically inert and serve only to compensate for the thickness of the other region or regions acting as an electrolyte layer. At least one of the electrochromic active layers 10 or 20 can be made with a non-constant thickness. but not zero, as illustrated in FIGS. 5G, 51-1 and 51. The electrolyte layer 30 can. The variation in thickness can, for example, be carried out progressively, with a constant decrease or not, in order to produce a gradient. The variation can be made 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. The thickness can also pass, along at least one direction of the plane, by an extremum, which can be a maximum or a minimum. To compensate for the variation in thickness of one of the layers of the stack, another layer at. less than 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 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 in different materials. These different materials may be electrochromic active but, alternatively, only one of the materials plays this role, the other may be electrochromically inert. The materials of the regions 20a and 201 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 polymer mixture, 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 which will only be visible for example when the device is activated and / or 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 chosen from polyaniline, polythiophene and polypyrrole and a dopant. Preferably, the electrochromic conductive polymer layer comprises a material chosen from polydiphenylamine, poly (4-amino biphenyl), poly (3-alkyl (Ci-a) 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. All the examples of structures illustrated in FIGS. 5A to 5C can be combined with each other, in variants that are not illustrated.

The electrochromic structure may comprise another optically active layer 308 which may serve as a background, especially colored, as illustrated in FIG. 6C.

The layer 200 may be continuous, as shown in Figures 6D and 6E, or discontinuous, as shown in Figures 6A and 6B. The layer 200 may in particular form a pattern. When the optically active layer comprises an interference pigment, the latter is for example a nacre or a goniochromatic pigment, arranged in a uniform or non-uniform layer, for example in a pattern. As an illustration of nacres that can be introduced as interference pigment, mention may be made of gold-colored mother-of-pearl sold by ENGELHARD under the name Brillant gold 212G (Timica), Gold 222C (CloisonneSparkle gold (Timica), Gold 4504). (Chromalite) and Monarch gold 233X (Cloisonne), the 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), the orange nacres especially marketed by ENGELHARD 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 ) the nacres of brown hue sold especially by Engelhard under the name Nu-antique copper 340XB (Cloisonne) and Brown CL4509 (Chromalite); nacres; copper-lightened especially marketed 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 the company Merck under the name Matte Blue (17433) (Microna), the white nacres with reflection silvered especially marketed by the company MERCK. under the name Xirona Silver and the golden greenish orange nacres sold especially by MERCK under the name Indian summer (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 the electrosensitive stack. 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 this case, the electrically sensitive stack of the electrochromic device may have a color which 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 be only 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 / A.1 / MgF 2, a diffractive pigment having this structure being marketed under the name SPECTRAFLAIR 1400 Pigment Siiver 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 electrochromic device may comprise at least one luminescent compound, sensitive to at least one wavelength causing its luminescence. 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 which may be suitable; mention may be made, inter alia, of the Luminux photoluminescent agent a) marketed by HONEYWELL, in particular Lurinux e Effect Blue A, Luminuxe Effect Green A and Lu.minux e Effect Red A. or the photoluminescent agent Netoje containing a high proportion of rare earths and marketed by NECITOKIN. In another exemplary embodiment of the invention, at least one photoluminescent agent may comprise a semiconductor, in particular in particulate form, for example Si, ZnO, CdSe, ... In an embodiment of the invention. at least one photoluminescent agent may comprise particles of average size ranging from about 1 nm to about 10 nm, for example in the form of CdSe, CdSe / ZnS or CdTe / CdS crystals. 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 metal pigment, especially a pigment for creating highlight points on the masked 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 for example be located in an optically active layer within the electrosensitive stack thereon or thereupon. The metal particles may be chosen from 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 silver-coated glass substrate, in the form of platelets, are sold under the name MICROGLASS METASHINE REFSX 2025 PS by the company TOYAL. Glass substrate particles coated with nickel / ehromelmolybdenum 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. especially TiO 2, iron including Fe 2 O 3, tin, chromium, barium sulfate and the following materials: MgF 2, CrF 3, ZnS. ZnSe, SiO2. Al 2 O 3, MgO, Y 2 O 3, SeO 3, SiO, HfO 2, ZrO 2, CeO 2, Nb 2 O 5, Ta 2 O 5, MoS 2 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 e by the company ENGELHARD. Other examples of reflective particles having 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 MC5090 PS or METASIIINE e MC280GP (2523) by the NIPPON SHEET GLASS, SPHERICAL SULVER POWDI.R DC 100, SILVER FLAKE JV 6 or GOLD POWDER A1570 by ENGELHARD, STARLIGHT REFLECTIONS FXM by ENERGY STRATEGY ASSOCIATES INC, BRIGHT SILVER @ 1 E 0.008X0.008 by MEADOWBROOK INVENTIONS, ULTRAMIN O (ALUMINUM POWDER FINE LIVING), and COSMETIC METALLIC POWDER VISIONARY BRIGHT SILVER BUCKET. COSMETIC METALLIC POWDER VISIONAIRE NATURAL GOLD 12 (60314) or COSMETIC METALLIC POWDER VISIONAIRE HONEY (60316) by the company ECKART. The electrochromic device can be made to vary the visual contrast between at least a first colored region and a second surrounding region, the color of which 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 one first region Ra whose color is predefined and at least one second region R2 adjacent to the first region. Ra, and whose color may change depending on the activation state of the electrochromic device. So. the color of the region R2 can be changed from a color in which the region Ra is clearly visible, as in FIG. 7C, to a state where the color of the region R2 is close to the region R.1 and where the region R, is difficult to discern, for 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 electro-sensitive stack. When the optically active layer comprises a liquid crystal, the latter may be chosen from the liquid crystal polymers present in the composition according to the invention is a polymer obtainable by polymerization of a monomer mixture comprising: ) at least one first monomer A of formula (I) Y1-A1-M1-A2-Y2 in which - i) Y1 and Y2, which may be identical or different, represent a polymerizable group chosen from acrylate or methacrylate groups, an epoxy group, an isocyanate group, hydroxy, vinylether (-O-CH = CH2) or vinylester (-CO-O-CH = CH2), and - ii) Al and A2, identical or different, represent a group of formula -CnH2n-, in where n is an integer from 0 to 20 and one or more methylene groups of said -CnH2n- group may be replaced by one or more oxygen atoms, and - iii) M1 denotes a group of general formula (I ') - R1-X1-R2-X2-R3-X3-R4-, wherein R1, R2, R3 and R4, which may be identical or different, denote a divalent group chosen from -O-, -COO-, -CONH: -, -CO-, -5-, -CEC-, -CH = CH-, - N = N- , -N = N (O) -, and -R2-X2-R3- or -R2-X2- or -R2-X2-R3-X3- may also be a simple covalent bond, and X1, X2, X3 being groups, which may be identical or different, chosen from 1,4-phenylene and 1,4-cyclohexylene groups. arylenes or heteroarylenes having an aryl ring comprising from 6 to 10 atoms optionally substituted by BI and / or B2 and / or B3, said heteroarylene containing from 1 to 3 heteroatoms chosen from O, N and S. The cycloalkylene groups having from 3 to 10 carbon atoms optionally substituted with -B 1 and / or -B 2 and / or -B 3, -B 1, -B 2, and -B 3, which may be identical or different, being chosen from C 1 -C 20 alkyl groups, C1-C20 alkoxy, C1-C20 alkylthio, (C1-C20) alkylcarbonyl, (C1-C20) alkoxycarbonyl, (C1-C20) alkylthiocarbonyl, -OH, -p, -Cl. -Br, -1, -CN, -NO2, formyl, acetyl, and alkyl, alkoxy or alkylthio groups having from 1 to 20 carbon atoms, interrupted by one or more oxygen atom (s) or one or more atoms of sulfur or one or more ester groups, and - b) at least one second chiral monomer B of formula (II) V 1 -A '1 -W 1 -Z-W 2 -A'2-V 2, wherein i) V1 and V2. identical or different, denote a group chosen from an acrylate or methacrylate group, an epoxy group, a vinyl ether or vinyl ester group, an isocyanate group, a C 1 -C 20 alkyl, a C 1 -C 20 alkoxy or a C 1 -C 20 alkylthio group. , (C 1 -C 20) alkoxycarbonyl, (C 1 -C 20) alkylthiocarbonyl, -OH, -F, -Cl. -Br, -I, -CN, -NO2, formyl, acetyl and alkyl, alkoxy or alkylthio groups, having from 1 to 20 carbon atoms, and interrupted by one or more oxygen atom (s) or one or more sulfur atom (s) or one or more ester groups (-CO-O-), and at least V1 or. V 2 denotes a polymerizable group chosen from acrylate or methacrylate groups, an epoxy group, an isocyanate group, hydroxy, vinyl ether (-O-CH = CH 2) or vinylester (-CO-O-CH-Cl 2), ii) A ' l and A ', which may be identical or different, represent a group of formula -CnH2n-, in which n is an integer ranging from 0 to 20 and one or more methylene groups of said CnH2n group may be replaced by one or more oxygen atoms; and iii) W1 and W2 denoting a divalent group of general formula R'1-X'1-R'2-X "2-R'3- in which R'l, R'2 and R'3 are identical or different, denote a divalent group chosen from -O-, -COO-, -CONH-, -CO-, -S-, -C = C-, -CH = CH-, -N = N-, -N = N (O) -, and R'l, R'2, R'3 or R'2-X'2 may also be a single covalent bond, and X '1 and X'2 are identical or different groups, selected from 1,4-phenylene, 1,4-cyclohexylene groups, arylenes or heteroaryl groups having an aryl ring comprising from 6 to 10 atoms optionally substituted with B'1 and / or B'2 and / or B'3, said heteroarylene containing from 1 to 3 heteroatoms selected from O, N and S. The groups cycloalkylenes having 3 to 10 carbon atoms optionally substituted with ùB '1 and / or ùB'2 and / or ùB' 3, -13'1, -'2, and ùB'3, identical or different, being selected from C 1 -C 20 alkyl, C 1 -C 20 alkoxy, C 1 -C 20 alkylthio, C 1 -C 20 alkylcarbonyl, C 1 -C 20 alkoxycarbonyl, C 1 -C 20 alkylthiocarbonyl, OH, -1-, -Cl, -Br, -I, -CN, -NO2, formyl. acetyl, and alkyl groups. alkoxy or alkylthio having from 1 to 20 carbon atoms, interrupted by one or more oxygen atom (s) or one or more sulfur atom (s) or one or more ester group (s), and Z denotes a chiral group divalent compound comprising at least 4 carbon atoms, in particular from 4 to 20 carbon atoms, and better still from 4 to 10 carbon atoms, (the divalent chiral group comprising at least one asymmetric carbon, in particular one or two asymmetric carbons, and particularly two asymmetric carbons) and in particular a divalent chiral group derived from the group of dianhydrohexites, hexoses, pentoses, binaphthyl derivatives (binaphthyl groups), biphenyl derivatives (biphenyl groups), tartaric acid derivatives or optically active glycols . Preferably, the liquid crystal polymer is obtained by polymerization of a mixture of monomers comprising: a) at least one first monomer A of formula (1) Y1-Al-Mt-A2-Y2 in which -i) Y1 and Y2, which may be identical or different, represent an acrylate or methacrylate group, preferably an acrylate group; ii) Al and A2, identical or different. represent a group of formula -CnH2n-, in which n is an integer ranging from 1 to 20, preferably ranging from 2 to 6, and more preferably equal to 4; Iii) M1 denotes a group of general formula (1 ') -R1-X1-R2-X2-R3-X3-R4-, in which R1 and R4 denote -O-, R2 and R3 denote -COO-. and X1, X2, X3 being a 1,4-phenylene group, the carbonyl group -CO- respectively of R2 and R3 being respectively attached to the group XI, X3, and. b) at least one second chiral monomer B of formula (II) V1-W1-Z-W2-V2, in which - i) VI denotes an acrylate or methacrylate group, and preferably an acrylate group, and V2 denotes a C1-C20 alkyl group, C1-C20 alkoxy, alkoxy (C1-C20) carbonyl, -OH, and preferably refers to a C1-C20 alkoxy group. especially C 1 -C 4, and in particular a methoxy group; ii) W i represents a divalent group of the formula X 'I -CO-O-, W2 represents a divalent group of the formula ûO-CO-X' 1, in which X '1 denotes a 1,4-phenylene group, and Z denotes a chiral group with two bonds. from the dianhydrohexite group. in particular a divalent radical of formula: In the definitions of the first monomer A described above, it is clear that the presence of groups of two or more oxygen atoms bonded to each other is excluded. Preferably, the monomer mixture comprises from 70 to 99% by weight of monomer A and from 1 to 30% by weight of monomer B, based on the total weight of monomer A and monomer B, and better comprises from 90 to 95% by weight. % by weight of monomer A and 5 to 10% by weight of monomer B. Preferably, the concentration of the polymerizable groups present in the mixture of monomer A and monomer B (polymerizable groups Y 1, Y 2 of monomer A and groups polymerizable Y 1, V 2 of monomer B) ranges from 3.2 to 15 mmol / g. The liquid crystal polymer defined above can be prepared according to the methods known in the art, such as those described in US 5362315, US 5807497, from the monomer mixture described above. For example, a mixture of monomers A and B defined above is applied to a smooth bottom and which is oriented, cross-linked three-dimensionally by polymerization of the monomer mixture and the bottom is separated. The film obtained after the polymerization is then milled into particles, in particular in the form of platelets. Preferably, the liquid crystal polymer particles have a larger size ranging from 1m to 3mm, and preferably from 30μm to 500μm. These particles are advantageously in the form of platelets. The particles can be separated (sorted) by a grain size selective process. -C) Such polymers and their particles are described in application EP-A-1046692. As liquid crystal polymer particles, those known as CTFA Polyacrylate-4 and sold under the names HELICONEIHC Sapphire, HELICONEIHC Scarabeus, HELICONE1HC Jade. FIELICONElIEC Maple, FIELICONEIHC XL Sapphire, HELICONE1HC XL Scarabeus, HELICONEIHC XL Jade, HELICONEIFIC XL Maple by WACKER. The electrochromic device may comprise at least one 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 at least one photochromic agent is used, the electrochromic device may be used to enable or not to excite the photochromic agent by the surrounding light. For example, if the photochromic agent changes its appearance due to exposure to light having a wavelength of 500 nm, in particular its modified color, the electrosensitive stack can be arranged to filter at least one wavelength. of excitation 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 electro-chromatic device can be used to improve the visibility of a beading or interference effect. For example, depending on a color of the electrosensitive stack of the electro-chromatic device and that of the interferential pigment (s), it is possible to amplify the perception of intensity of the color. For example, if the electrochromic device contains at least one mother-of-pearl, for example in one of the layers of the stack or on its surface, for example a red mother-of-pearl, and if the electrochromic device makes it possible to modify the 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 the electrosensitive stack of the 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 zone can be reduced. 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. the color path of a goniochromatic pigment can be more or less revealed on demand, for example to increase or not a volume effect. The electrochromic device can be used to selectively enhance the colonel 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 electrochromic device, this layer containing an interference pigment, for example a mother-of-pearl giving an iridescent effect, or a liquid crystal, the nacres of gold color 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); 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); 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 the company Merck under the name Matte 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 BLACKSTAR 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) from MERCK or even FLAMENCO TWILIGHT RED, FLAMENCO 25 TWILIGHT GREEN, FLAMENCO TWILIGHT GOLD, 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), NARROW ANTIQUE CLOISONNE RED FLAMBE (code 440 XB), ANCIENT BRONZE NARROW CLOISONNE (240 XB), ANTIQUE GOLDEN CLOISONNE (222 CB) and ANTIQUE CLOISONNE COPPER (340 XB) from 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. FIGS. 7I 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 include an integrated power 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 may be fixed or spring-mounted. to fit the finger more easily. 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 in FIGS. 1A and 1B, bearing 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 may include, where appropriate, 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. All you have to do is place your finger on the panel and visualize the drawing, the diagram, or the photograph of your finger or nail that corresponds 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 in packets of electrochromic false nails (for both hands), with for example among these false nails 2 copies of width between 1.1 cm and 1, 3em, preferably 2 copies width 1.2cm (for inches), 2 copies width between 0.6cm and 0.8cm, preferably 2 copies width 0.7cm (for earphones), and 6 copies width between 0.8cm and 1.0cm, preferably 6 copies 0.9cm wide (for 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 energy source 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 reached. 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 through 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 shown in Figure 4 can be added to one. any of the stacks described in Figures 5A to 51 and 6A 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 of. result.

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 as a mixture or juxtaposed: poly (3-methyl-thiofen): poly (3,3-dimethyl-3, 4-dihydro-2H-methyl-3,4-b] dioxepine: poly (3,4-ethylenedioxypyrrole) (a) and poly (3,4-propylenedioxypyrrole) (Pprodop) (b) [representative of PXDOT derivatives (poly (3,4 -alkylenedioxypyrrole): (a) poly (N-sulfonatopropoxy-ProDOP): [poly (bis-ethylpentoxypyrrole-N-methylcarbazol)] Poly (bis-ethylendioxypyrrole-pyridine): 15-Poly (bis-ethylene dioxypyrrole-pyridopyrazine) Poly- (benzo [c] thiophene-N-2-ethylhexyl-4,5-dicarboxylic imide): Poly (2,2 '- [10-methyl-3,7-phenothiazylene] -6,6'-bis [ 4-phenylquinoline): The electrolyte layer may comprise one or more polymers chosen, for example, from the following list: alone, as a mixture, or in a juxtaposed way: According to the invention, the electrochromic conductive polymer layer may comprise, for example, a mast riau selected from polyaniline, polythiophene, and polypyrrole and a dopant. Preferably, the electrochromic conductive polymer layer comprises a material chosen from polydiphenylamine, poly (4-amino biphenyl), poly (3-alkyl (Ci-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 PROPOSED (The proportions are by weight) EXAMPLE 1 On a support and electrode layer available from the company Shieldal (USA), formed of polyethylene terephthalate (PET) coated with transparent oxide electrically conductive ITO (Indium Tin Oxide), by For example, a 3 cm 3 stretch, a polyethylene dioxythiophene solution (sold under the reference Baytron and available from Bayer) to which 3% of Xirona Kiwi-pink goniochromatic pigment (Merck company) was added. 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 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%. 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 Baytrone layer is non-uniformly deposited. The spreader is set to have two sides at different heights. It is possible to obtain a color gradient, which exhibits a color change by changing the potential between -1.5 V and 1.5 V. EXAMPLE 5 The multilayer structure of Example 1 is applied to a false nail. The layers of Baytrone and polypyrrole are connected to electrical conductors located on the underside of the false nail and the tip 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 6 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 can be observed by changing the potential between -1.5 V and + 1.5 V. EXAMPLE 7 In this example, we take up the multilayer structure of Example 1, which IO connects to a battery SR 416 button, placed under the multilayer structure. An insulating sheet such as a polyethylene film, which acts as a switch, is introduced into the electrical circuit. In the case of nail makeup, the insulating sheet may initially be in contact with one of the terminals of the battery under the device; at the end of the nail. Example 8 This example differs from Example 7 in that the device is provided with a touch switch, for example of the type Pf1AP 3391, available from the company APEM. The switch can be placed under the multilayer structure at the end of the nail. Example 9 This example differs from Example 7 in that an adjustable potentiometer, for example CERMET CMS, is introduced into the electrical circuit in order to vary the intensity of the excitation current. EXAMPLE 10 This embodiment differs from Example 1 in that it comprises five alternating layers of cellulose acetate butyrate 5 m thick and polyethylene 51 of thickness 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 11 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 12 An adhesive coated with a layer of 50 gm of Dispofix 645 E (available from National Adhesives) is brought into contact with the underside of the electrochromic device of Example I. Pressure is exerted to promote adhesion . A protective film of the adhesive is removed at the time of application.

EXAMPLE 13 3% of Metashine Silver pigment (Nippon Sheet Glass Company) is added to the optically active layer proposed by Example 1 instead of 3% of goniochromatic pigment. 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. EXAMPLE 14 13% of Heiicone ™ Scarabeus pigment (Wacker company) is added to the optically active layer proposed by the example instead of 3% of goniochromatic pigment. In this way, the increased electrochromatic effect of the optical effect of the liquid crystal 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 "comprising a" shall be understood as being synonymous with "comprising at least one" unless the contrary is specified.

Claims (10)

REVENDICATIONS1. Cosmetic device (1) to be applied to human keratin materials, comprising: - an optically active layer (200) comprising an interference pigment. or a liquid crystal, an electrochromic multilayer structure located under the optically active layer. 2. Device according to claim 1, the optically active layer comprising a mother-of-pearl. 3. Device according to claim 1, the optically layer comprising a goniochromatic pigment. 4. Device according to claim 1, the optically active layer comprising a liquid crystal. 5. Device according to any one of claims 1 to 4,. the electrochromic structure can take a dark state on the one hand and a clear or transparent state on the other hand, depending on its electrical excitation. 6. Device according to any one of claims 1 to 5, the optically active layer completely covering the electrochromic structure. 7. Device according to any one of claims 1 to 6, the electrochromic structure comprising an electrosensitive stack comprising: - electrode layers (40, 50), active electrochromic layers (10, 20), an electrolyte layer (30). 8. Device according to any one of claims 1 to 7, being configured to attach to a fingernail. 9. Device according to any one of claims 1 to 8, the optically active layer (200) defining a pattern. 10. A process for making up human keratin materials, wherein a device as defined in any one of claims 1 to 9 is fixed thereto.