FR2846861A1 - Artificial finger nail comprises organic resin and reinforcing fibres pre-impregnated with organic photopolymerisable matrix - Google Patents

Abstract

The flexible artificial fingernail, designed to cover at least part of a natural nail and made from reinforcing fibres, e.g. of glass, ceramic or polymer material, and an organic resin finishing layer, has the fibres pre-impregnated with an organic photopolymerisable matrix that is made to be completely photopolymerised when placed on the natural nail to form a hard, non-porous material. The organic matrix is partially polymerised before the artificial nail is applied to the natural one, and the fibres can be woven or non-woven, parallel or laid at random. The fibres can be mineral, organic or optical fibres, and the resin has a refraction index just below that of the optical fibres.

Description

Deformable artificial nail and method for strengthening a natural nail

implementing it.

  TECHNICAL FIELD OF THE INVENTION The invention relates to a deformable artificial nail intended to be placed on at least part of a natural nail and comprising a reinforcement of fibers and

  a top coat of organic resin.

   State of the art The most common techniques for the construction and installation of artificial nails consist either of making the artificial nail by applying a resin directly on the natural nail, or of sticking on a part of the natural nail. a

  artificial nail preformed with a glue generally of cyanoacrylate type.

  Thus there are artificial nails in the form of a rigid capsule, made of plastic and glued to the natural nail. These nails, often too rigid, do not always adapt to the shape of the natural nail, forcing the manicures to exert pressure on the nail until the glue sets. This can result in the presence of air bubbles causing polymerization defects, yeast infections or accidental detachments. In addition, when the natural nail grows, an unsightly demarcation can be created between the natural nail and

the artificial nail.

  Document FR-Ai2584280 describes an artificial nail tip intended to form a longitudinal extension of a natural nail and comprising a molded synthetic sheet constituting a piece of fabric. The piece of fabric is fixed to the natural nail using a cyanoacrylate type glue. The artificial nails to be glued, however, require great precision, the positioning errors not being rectifiable with this glue. In addition, cyanoacrylate type adhesives are very toxic and often a source of allergy. These nails, generally made of organic resin, are also fragile and have

  low mechanical and impact resistance.

  Some have attempted to improve the mechanical properties of artificial nails, using reinforcing elements such as fibers. In most cases, the reinforcement, for example a fiber fabric, must be impregnated with a resin when applying the artificial nail to the natural nail. Document US4860774 describes a material and a method for strengthening natural nails. The material comprises a glass fiber cloth, soaked in an aqueous suspension comprising a monomer and a polymer. The fiber fabric, once dried, is porous. One of the surfaces of the fabric is coated with an adhesive intended to stick the fiber fabric to a natural nail, while the other surface is coated with a gummed paper, then with a self-curing varnish. However, this type of material requires a large number of operations before the artificial nail can be placed on the natural nail, in particular the manual impregnation of a resin, which makes the implementation of artificial nails

  long and tedious for manicures.

  OBJECT OF THE INVENTION The object of the invention is to provide a deformable artificial nail which is easy to use.

  on a natural, impact-resistant and natural-looking nail.

  According to the invention, this object is achieved by the fact that the fiber reinforcement is prepreg with a photopolymerizable organic matrix intended to be fully photopolymerized when the prepreg fiber reinforcement is

  laid on the natural nail, so as to form a hardened, non-porous material.

  According to a development of the invention, the organic matrix comprises

photo-initiating agents.

  According to a preferred embodiment, the organic matrix prepreg 10 the fiber reinforcement is partially polymerized, before laying the nail

artificial on the natural nail.

  Another object of the invention is a method for strengthening a natural nail

  using a deformable artificial nail.

  According to the invention, this object is achieved by the fact that: the fiber reinforcement preimpregnated with photopolymerizable organic matrix is placed on the natural nail previously cleaned and degreased and takes the form of the natural nail, the organic matrix allowing relative adhesion of the fiber reinforcement to the natural nail, - the pre-impregnated fiber reinforcement is then subjected to radiation

  luminous completely polymerizing the organic matrix, so that the organic matrix is fully polymerized and forms with the fiber reinforcement 25 a hardened composite material, adhering perfectly to the natural nail.

  According to a development of the invention, a top layer of photopolymerizable organic resin is deposited on the fiber reinforcement

  prepreg before it is subjected to light radiation.

  According to another characteristic of the invention, the reinforcement of prepreg fibers is deposited on a sublayer of photopolymerizable organic resin, it

  even deposited on the natural nail.

  Description of particular embodiments.

  A deformable artificial nail comprising a fiber reinforcement impregnated with a light-curing organic matrix is intended to be placed on at least part of a natural nail. It can be used to strengthen part of the natural nail, if it is broken for example, or be placed on the whole of the natural nail for aesthetic reasons. After laying on the natural nail,

  the artificial nail is covered with a top coat of organic resin.

  The fibers constituting the fiber reinforcement can be organic or mineral.

  By way of example, the fibers can be chosen from fibers of glass, ceramic, silica, aramid, carbon or boron, natural silk, polyester or polyamide. The fibers may also be optical fibers, the refractive index of the resin then being close to but less than that of the fibers. The arrangement of the fibers within the reinforcement can be

  variable. Thus the fiber reinforcement can be woven nonwoven and can include fibers arranged parallel or randomly with respect to each other. Depending on the use, the fibers can be transparent, translucent, textured, invisible to the eye or, on the contrary, visible or comprising a pattern.

  The fiber reinforcement is pre-impregnated by a light-curing organic matrix coating all of the fibers and filling all the free spaces arranged between the fibers, so as to form a non-porous artificial nail and to obtain a high quality final material. For example, the volume ratio of organic matrix pre-impregnating the fiber reinforcement can vary from 40% to 80%, or more depending on the properties sought. Pre-impregnation of the fiber reinforcement makes it possible to obtain an artificial nail ready for use and it avoids, during the laying of the artificial nail, possible contamination. The prepreg fiber reinforcement is initially flat and flexible, which allows it to adapt to any form of natural nail or

  portion of natural nail, by simple manual pressure.

  By photopolymerizable organic matrix is meant an organic matrix capable of being polymerized by light radiation, without adding or removing material. The light radiation can be, for example, ultraviolet or visible radiation. The organic matrix is intended to be completely photopolymerized when the prepreg fiber reinforcement is placed on the natural nail, so as to form a hard, dense and non-porous material. The organic matrix can be of any type, provided that it is biocompatible and has a perfect bond with the type of fibers used for the reinforcement of fibers. As an example, it is possible to use an organic matrix

  constituted by a resin chosen from the group consisting of acrylate, methacrylate, aromatic or aliphatic resins. Among the methacrylate resins, use may in particular be made of mono-, di-, tri- or tetramethacrylate resins.

  The organic matrix can thus be chosen from Bisphenol A derivatives, such as BIS-Gma (BIS-phenol A-glycidyl dimetacrylate), from methacrylated Bisphenol A epoxy resins or aliphatic or aromatic methacrylate urethane resins. Among the acrylate resins, the organic matrix can be chosen from mono-, di, tri- or tetra-acrylate resins. The organic matrix may, for example, be chosen from epoxy acrylate resins, such as acrylated Bisphenol A resins, aromatic or aliphatic acrylate urethane resins, polyester arcrylate resins. The organic matrix can also be a mixture of resins hardening by

radical polymerization.

  The organic matrix can comprise mineral or organic fillers intended to vary the tack, the viscosity and the rheology of the deformable artificial nail 10, according to the conditions of use. For example,

  mineral fillers can be beads or hollow glass spheres, crushed glass particles, glass, carbon or ceramic microfibers, talc, calcium carbonate, thixotropic agents such as collodal or pyrogenic silica. The organic fillers can, for example, be polyethylene or polypropylene powders.

  The organic matrix also comprises photo-initiating agents intended to initiate the polymerization of the organic matrix as soon as it is subjected to light radiation. The photoinitiators can be of any known type. These are, for example, oxides of acyl phosphine,

  ketones, thioxanthones, benzylic ketals or camphroquinone ...

  The integration of the photoinitiators into the organic matrix prevents the manicure from making the mixture and makes it possible to obtain a controlled polymerization, in contrast to the inhomogeneous mixtures of paste and catalysts carried out manually by the manicure.

  The organic matrix can be partially polymerized, before laying the artificial nail on the natural nail, according to the flexibility of the desired artificial nail.

  Thus, if it is desired to give a specific shape to an artificial nail, or for applications of small surfaces such as the nail dressing, use will be made of a prepreg fiber reinforcement whose organic matrix is little or not crosslinked. In the case of application of artificial nails of standard shape, very good flexibility is not necessary. Partial polymerization of the organic matrix is then possible, thus making the handling of the prepreg fiber reinforcement easier. However, it is necessary that the total polymerization of the organic matrix takes place after the laying of the prepreg of fiber reinforcement on the natural nail, so as to obtain a deformable, flexible and memory foam artificial nail, before laying on the nail

  natural, and to ensure good adhesion to the nail.

  The assembly formed by the fibers and the organic matrix can be translucent,

  letting through the light rays activating the polymerization of the organic matrix. The tack, viscosity and rheology properties can also be adjusted and controlled according to the desired use and handling, by varying the nature, the amount of the organic matrix and the charges doping it.

  For example, an organic matrix based on Bis GMA resin has a viscosity of 10 to 30 Pa.s at 250C. If the resin is doped with 1 to 2% of collodal silica, its viscosity varies between 40 and 60 Pa.s at 250C. On the contrary, the addition of 25 hydrophilic glass microbeads in the initial formulation has a slightly fluidizing effect and the formulation comprising microbeads has a viscosity of between 8 and 20 Pa.s at 250C. A formulation based on urethane acrylate has a viscosity of 8 to 15 Pa.s at 250C while the same formulation doped with

  2 to 3% of pyrogenic silica has a viscosity between 40 and 50 Pa.s.

  Reinforcement of at least part of a natural nail using a deformable artificial nail can be carried out as follows: The natural nail intended to be reinforced is prepared according to the usual techniques (elimination of the skins, cuticle treatment, light polishing ...). - We select a flat pre-impregnated fiber reinforcement of adequate size.

  - The preimpregnated fiber reinforcement is placed directly on the previously dusted and degreased nail and takes the form of the natural nail by simple manual pressure.

  The rheology and the tackiness of the organic matrix as well as the flexibility of the artificial nail, allow good wetting of the surface of the natural nail and relative adhesion of the fiber reinforcement to the natural nail. By relative adhesion is meant that the artificial nail can still be moved relative to the natural nail, its positioning thus being able to be adjusted as long as the polymerization of the organic matrix is not complete. However, the entire surface of the deformable artificial nail adheres to the natural nail, so

  that no bubble or detachment can take place.

  - The artificial nail is then exposed to light radiation, for example ultraviolet. The organic matrix completely polymerizes, causing both the hardening of the artificial nail and the perfect adhesion of the artificial nail to the natural nail. The organic matrix then forms with the fiber reinforcement a cured composite material.

  - A top coat of organic resin is deposited on the artificial nail, to shape and give the final shape to the finished artificial nail, according to

usual techniques.

  The topcoat is preferably light-curing and subjected to a

  light radiation allowing it to fully polymerize and harden.

  It preferably comprises at least one constituent of the same kind as one of the constituents of the organic matrix, so as to obtain a perfect bond between the finishing layer and the fiber reinforcement preimpregnated with organic matrix. By way of example, the finishing layer can be constituted by a mixture of a diacryalate resin based on Bisphenol A to guarantee a shiny appearance and good hardness, and of an aliphatic urethane diacrylate resin intended to increase resistance to solvents and adhesion with the prepreg fiber reinforcement. The mixture can be primed with an aromatic ca-amino ketone. It is also possible to add a reactive diluent of

  polyetherpolyoltriacrylate type to adjust the final viscosity.

  According to an alternative embodiment, the finishing layer can be deposited on the pre-impregnated fiber reinforcement before this is subjected to light radiation, the pre-impregnated fiber reinforcement and the protective layer.

  finish then being polymerized simultaneously.

  According to another embodiment, a sublayer of photopolymerizable organic resin is deposited on the natural nail, the reinforcement of prepreg fibers 25 being then deposited and adhering to the sublayer. The organic matrix is transparent to light radiation, so as to allow the polymerization of the undercoat at the same time as the polymerization of the

organic matrix.

  The sublayer preferably comprises at least one constituent of the same nature as one of the constituents of the organic matrix, so as to obtain a perfect bond between the sublayer and the reinforcement of fibers prepreg of organic matrix. For example, the organic resin underlay may be a mixture of modified vinylester resin selected for its high reactivity and a urethane diacrylate chosen for its flexibility, its low shrinkage and its adhesion to the nail. The transparency of the assembly constituted by the pre-impregnated fiber reinforcement and the sub-layer makes it possible to control a positioning error and to expel any air bubbles present. The assembly is then subjected to light radiation, for example ultraviolet, so as to completely polymerize the organic matrix of the prepreg fiber reinforcement and the undercoat in organic resin. The finishing layer is then deposited on the assembly to form the final artificial nail according to the usual techniques. The organic matrix can be partially polymerized, before laying the prepreg fiber reinforcement on the natural nail or on the organic resin underlay. However, it is completely polymerized by the light radiation used once the pre-impregnated fiber reinforcement 20 is placed on the natural nail or on the organic resin undercoat. The polymerization not only allows the hardening of the prepreg fiber reinforcement and the undercoat, if it is deposited on the natural nail, but also the adhesion of the prepreg fiber reinforcement.

  or the whole formed by it and the undercoat on the natural nail.

  The artificial nail with a prepreg fiber reinforcement has many advantages. Indeed, it makes it possible not to use glue of cyanoacrylate type since the organic matrix and possibly the undercoat in organic resin serve as adhesive by polymerizing directly on the nail

  natural. In addition, the pre-impregnated fiber reinforcement being flexible and deformable, it adheres to any form of natural nail and remains spontaneously attached to it.

  This prevents the formation of bubbles which are often the cause of

  polymerization, yeast or accidental detachment.

  The fiber reinforcement allows the artificial nail to have higher mechanical properties than an artificial nail comprising only an organic resin, which allows either to make more resistant artificial nails or, to

  equivalent mechanical properties, to make finer artificial nails.

  For example, ABS (acrylonytrile-Butadiene-Styrene), commonly used for the manufacture of nail capsules, exhibits a flexural breaking stress of 50 to 70 MPa, a flexural modulus of 1.8 to 2.8 GPa, a tensile strength of 25 to 40 MPa and a Young's modulus of 1.6 to 2.6 MPa. 15 A modified, unreinforced vinyl ester resin has resistance to

  tensile failure from 70 to 80 MPa and a Young's modulus from 3.1 to 3.5 GPa.

  This same resin reinforced by 20 to 30% by mass with a glass fiber fabric then has a tensile breaking strength of 200 MPa in the direction of the fibers, with a Young's modulus of 8 to 12 GPa. For a rate of 40 to 20 60% by mass of glass fiber fabric, the breaking strength in the

  fiber direction is then 400 MPa, with a Young's modulus of 20 GPa.

  Thus a nail made of an organic matrix reinforced to 30% by mass with a glass fiber fabric has a tensile strength 2.5 to 3 times greater than that of a nail made only of an organic matrix and 5 25 to 8 times greater than that of an ABS nail.

  In addition, a nail made of unreinforced organic matrix, of rectangular section of 0.4 mm × 10 mm has a tensile breaking strength of 280N. For the same tensile breaking strength, an artificial nail made of an organic matrix reinforced with 30% by mass of glass fibers will have a section of 10mm x 0.15mm, ie a thickness 2.6 times thinner. An artificial nail made of an organic matrix reinforced to 30% by mass of a glass fiber fabric twice as thick as an ABS nail has a breaking strength 3 times greater than the latter. The use of the same organic matrix to impregnate the fibers and to participate in the adhesion of the artificial nail as well as in its formation avoids any light diffraction, which gives the artificial nail a more natural and 10 more homogeneous behavior. It also allows the manicure to save time when applying the artificial nail. In addition, the manicure does not need to sand the upper edge of the prepreg fiber reinforcement,

  this disappearing under the top coat.

Claims (19)

claims   1. Deformable artificial nail intended to be placed on at least part of a natural nail and comprising a fiber reinforcement and a finishing layer in   organic resin, artificial nail characterized in that the fiber reinforcement is pre-impregnated with a light-curing organic matrix intended to be fully light-cured when the pre-impregnated fiber reinforcement is placed on the natural nail, so as to form a hardened material and not porous.   2. Artificial nail according to claim 1, characterized in that the matrix   organic contains organic or mineral fillers.   3. Artificial nail according to one of claims 1 and 2, characterized in that the organic matrix comprises photo-initiating agents.   4. Artificial nail according to any one of claims 1 to 3, characterized in   what the organic matrix preimpregnating the fiber reinforcement is   partially polymerized, before laying the artificial nail on the natural nail.   5. Artificial nail according to any one of claims 1 to 4, characterized in   that the fiber reinforcement is non-woven.   6. Artificial nail according to any one of claims 1 to 5, characterized in that the fibers are arranged in parallel.   7. artificial nail according to any one of claims 1 to 5, characterized in   that the fibers are arranged randomly in the fiber reinforcement.   8. An artificial nail according to any one of claims 1 to 4, characterized in   what the fiber reinforcement is woven.   9. Artificial nail according to any one of claims 1 to 8, characterized in   what fibers are mineral or organic fibers.   10.Artificial nail according to any one of claims 1 to 8, characterized in   that the fibers are optical fibers, the refractive index of the resin being close to but lower than that of optical fibers. 10 11. Method for strengthening a natural nail using an artificial nail   deformable according to any one of claims 1 to 10, characterized in   that: - the fiber reinforcement pre-impregnated with light-curing organic matrix 15 is placed on the natural nail previously cleaned and degreased and takes the form of the natural nail, the organic matrix allowing relative adhesion of the fiber reinforcement to the natural nail, the pre-impregnated fiber reinforcement is then subjected to a light radiation completely polymerizing the organic matrix, so that the organic matrix is fully polymerized and forms with the reinforcement of   fiber a hardened composite material, adhere perfectly to the natural nail.   12. A method for reinforcing a natural nail according to claim 11, characterized in that a finishing layer of photopolymerizable organic resin is deposited on the reinforcement of prepreg fibers before   that it is not subjected to light radiation.   13. A method for reinforcing a natural nail according to claim 11, characterized in that a finishing layer of photopolymerizable organic resin is deposited on the cured composite material and is subjected to light radiation.   14. A method for strengthening a natural nail according to one of claims 12 5 and 13, characterized in that the organic resin layer comprises at least   a constituent of the same nature as one of the constituents of the organic matrix.   15. A method for strengthening a natural nail according to any one of the   Claims 11 to 14, characterized in that the pre-impregnated fiber reinforcement 10 is deposited on an organic resin underlay   light-curing, itself deposited on the natural nail.   16. A method for strengthening a natural nail according to claim 15,   characterized in that the organic resin sublayer comprises at least one constituent of the same nature as one of the constituents of the organic matrix.   17. Method for strengthening a natural nail according to one of claims 15   and 16, characterized in that the organic matrix is transparent to light radiation, the sublayer and the organic matrix being polymerized simultaneously by light radiation.   18. A method of strengthening a natural nail according to any one of   claims 11 to 17, characterized in that the light radiation is   in the ultraviolet or visible range.   19. A method of strengthening a natural nail according to any one of   claims 11 to 18, characterized in that the organic matrix is   partially polymerized before installation of the prepreg fiber reinforcement.