Drug – bio-affecting and body treating compositions – Manicure or pedicure compositions
Reexamination Certificate
1997-03-28
2001-08-28
Travers, Russell (Department: 1617)
Drug, bio-affecting and body treating compositions
Manicure or pedicure compositions
C424S401000, C526S319000, C526S320000, C526S321000, C526S327000, C526S329000, C526S340200, C526S346000
Reexamination Certificate
active
06280713
ABSTRACT:
The invention related to novel nail varnishes containing microgels as well as to the use of these microgels for modifying the physical properties of said vanishes and/or film obtained.
The present invention is situated most particularly in the field of nail varnishes comprising an essentially non-aqueous organic solvent medium. In such nail varnishes, the solvent or the mixture of solvents conventionally represents between 50 and 80% by weight of the total weight of the nail varnish. The organic solvents which are conventionally used are low molecular weight esters, particularly ethyl, propyl or butyl acetates. The organic solvent medium may also contain low molecular with alcohols, particularly ethanol, isopropanol or butanol, or ketones, particularly acetone or methyl or methyl ketone.
In the sense of the invention, <nail varnish comprising an essentially non-aqueous organic solvent> or more simply <organic solvent nail varnish> will refer to nail varnishes in which the solvent comprises at most 1% water and is composed of at least one of the solvents defined above.
Generally, organophilic clays are used in the organic solvent nail varnishes for preventing the sedimentation of pigments. Smectites, hectorites, bentonites and quaternised montmorillonites will be cited as examples of organophilic clays commonly used to this end. The use of these products has disadvantages which are well-known to nail varnish formulators: in fact, they strongly lower the adhesion of the varnish, furthermore they also lower its brightness and, the other disadvantage is that they generally necessitate the presence of toluene in the formulation.
Generally, in nail varnishes comprising an organic solvent, the main part of the dry extract is due to the presence of nitrocellulose.
The applicant has now discovered that a part or even the whole of the nitrocellulose contained in the organic solvent nail varnishes could be replaced by microgels and that furthermore, in a totally surprising way, the presence of microgels in the nail varnish compositions enabled improving the rheological properties of the varnish and/or film, particularly enabling preventing the precipitation of the pigments. This remarkable property enables appreciably lowering, even doing away with the amount of organophilic clays generally used to this end in nail varnishes, but whose disadvantages are well-known, as it has been revealed above.
Furthermore, nail varnish formulation specialists know that, amongst the other problems to be solved, it is notably essential to find a good compromise which enables having a high dry extract without however increasing the viscosity of the product in too significant a way. This is particularly sharp when the preparation of a varnish enabling obtaining a beautiful aspect of the nail surface with one sole varnish layer is sought-after. Such a varnish is commonly referred to as <one coat> by the person skilled in the art.
In fact, in order for a varnish of this type may, in one sole layer, form a film that covers sufficiently, it is generally necessary to increase the amount of pigments. However, it is necessary to watch so as not to exceed a certain pigment concentration, since it would be possible for this to be detrimental to the brightness of the film obtained. It could be possible to consider increasing the thickness of the film by increasing the quantity of nitrocellulose and/or resin, but in this case, a problem of application of the varnish is come up against due to too high a viscosity. In order to attempt to solve this problem, it has been proposed to lower the grade of the nitrocellulose used, but then the quality of the film is decreased and it becomes more fragile and chips.
Now, the applicant has demonstrated that the incorporation of a microgel in a nail varnish formula enabled increasing the dry extract of the varnish in a surprising way without meaning appreciably increasing its viscosity.
Thus, the present invention enables in particular providing a solution to the problem of the formulation of <one coat> nail varnishes such as defined above.
According to one of its essential characteristics, the invention relates to nail varnishes comprising an essentially non-aqueous organic solvent medium containing, as well as the usual constituents of nail varnishes, at least one microgel, said microgel not being obtained from an acrylic polymer microdispersion prepared by radical polymerisation of at least one acrylic monomer in the presence of a poly(methyl methacrylate) (PMMA). (PMMA) or a poly(tert-butyl acrylate) (PtBuA)-based block copolymer.
The microgel which can be used for preparing the nail varnishes according to the invention may be any microgel, in particular the microgels such as have been defined by W. FUNKE et al., <Intramolecularly Crosslinked Macromolecules. Formation and structure. Characterization and Particules Properties>, Polym. Internat., 30, 519, (1993). In this publication, FUNKE et al. give a complete definition of the microgels in insisting on the following points: the solubility being a characteristic common to microgels and linear polymers, the microgels differ from the linear or branched polymers by a three-dimensional cross-linked network. The diameters of their particles is lower than 100 nm and their molecular mass is in general greater than 10
6
g/mol. From this fact, it is possible for the microgels to be dispersed in order to form transparent or slightly opalescent colloidal solutions.
The microgels obtained from an acrylic polymer microdispersion prepared by radical polymerisation of at least one acrylic monomer in the presence of a poly(methyl methacrylate) (PMMA)- and tert-butyl polyacrylate(PAtBu)-based block copolymer have intentionally been excluded from the list of usable microgels according to the invention in order to take into account U.S. Pat. No. 5,711,940 which provides stable microdispersions and microgels based on acrylic polymers, as well as the method of obtaining them, and compositions, notably cosmetic compositions composing them.
According to a particularly advantageous variant of the invention, the microgel comprises a cross-linked polymer based on a monofunctional monomer known as principal monomer, and a difunctional monomer acting as cross-linking agent.
The principal monomer will advantageously be selected from the acrylic, methacrylic, styrenic or vinylic ester monomers. Preferably said vinyl ester has a C1 to C18 alkyl group.
More specifically, these monomers will be selected from the family comprising:
the alkylacrylates and alkylmethacrylates having linear or branched C1 to C6 alkyl groups, or a mixture thereof,
styrenic monomers,
vinylic esters having C1 to C8 alkyl groups, for example vinyl acetate.
The difunctional monomers of cross-linking agent function will advantageously be selected from the following, for example butandiol dimethacrylate, diethyleneglycol dimethacrylate, diethyleneglycol dimethacrylate, tetraethyleneglycol dimethacrylate,
the difunctional aromatic monomers, for example divinylbezene.
The various monomers in the family of monomers of the acrylic or methacrylic type will be preferentially selected. The proportion of cross-linking of the microgels represented by the proportion of difunctional monomer with respect to the monofunctional monomer is advantageously between 0.5 and 40% by weight, preferably between 0.5 and 15%.
Such microgels are, for certain ones, commercially available. The microgels marketed by Nippon Paint will particularly be cited.
It is also possible for these microgels to be obtained by swelling a microlatex prepared by radical polymerisation of a monofunctional monomer such as defined above, in a solvent and in the presence of a cross-linking monomer and a surfactant, preferably an anionic surfactant.
In order to prepare these microgels, micellar solutions of surfactants will be particularly prepared in the presence of which the microlatexes will be prepared by any polymerisation method in the presence of an organosoluble or hydrosoluble initiator as descr
Meybeck Alain
Riess Henri-Gerard
Tranchant Jean-Francois
Bierman, Muserlian and Lucas
LVMH Recherche
Travers Russell
Wang Shengjun
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