Fine dispersion of melanin pigments, its preparation and its use in cosmetics

Claim 2

Dispersion of melanin pigments, characterized in that it contains, in a medium chosen from: a) liquids chosen from: linear or branched monoalcohols containing at least 3 carbon atoms; linear or branched polyols containing at least 2 carbon atoms; saturated or unsaturated cycloaliphatic alcohols containing at least 6 carbon atoms; aromatic alcohols containing at least 6 carbon atoms; esters of C 8 -C 22 fatty acids and C 1 -C 6 alcohols or C 2 -C 6 polyols; esters of C 1 -C 6 aliphatic acids or aromatic acids and C 8 -C 22 fatty alcohols; esters of C 8 -C 22 fatty acids and C 8 -C 22 fatty alcohols, esters of C 6 -C 22 alcohols and polyacids, and diesters of hydroxylated fatty acids; linear or branched paraffins containing at least 8 carbon atoms; silicone oils; and the mixture of these various compounds, or b) an emulsion consisting of a water-immiscible liquid defined above, water and an emulsifying agent, a melanin pigment in the form of particles, for which at least 75% of the particles have a particle size lower than 10 microns.

Claim 3

Dispersion according to claim 1, characterized in that at least 85% of the particles have a particle size lower than 5 microns.

Claim 4

Dispersion according to claim 1 characterized in that the concentration of melanin pigments in the dispersion is between 5 and 50% by weight relative to the total weight of the composition.

Claim 5

Process for the preparation of a dispersion according to claim 1 characterized in that, into a liquid medium chosen from: a) a liquid chosen from: a linear or branched monoalcohol containing at least 3 carbon atoms; a linear or branched polyol containing at least 2 carbon atoms; a saturated or unsaturated cycloaliphatic alcohol containing at least 6 carbon atoms; an aromatic alcohol containing at least 6 carbon atoms; an ester of a C 8 -C 22 fatty acid and a C 1 -C 6 alcohol or a C 2 -C 6 polyol, an ester of a C 1 -C 6 aliphatic acid or an aromatic acid and a C 8 -C 22 fatty alcohol, an ester of a C 8 -C 22 fatty acid and a C 8 -C 22 fatty alcohol, an ester of a polyacid and a C 6 -C 22 alcohol, a diester of a hydroxylated fatty acid; a linear or branched paraffin containing at least 8 carbon atoms; a silicone oil; and the mixture of these various compounds, or b) an emulsion consisting of a water-immiscible liquid defined above, water and an emulsifying agent, there is introduced a melanin pigment of natural or synthetic origin and in that grinding is performed in a liquid medium until at least 75% of the particles have a particle size lower than 10 microns.

Claim 6

Process according to claim 4, characterized in that the melanin pigment introduced into the grinding medium has a particle size between 15 and 25 microns.

Claim 7

Process according to claim 4, characterized in that a melanin pigment of natural or synthetic origin is used.

Claim 8

Process according to claim 6, characterized in that the melanin pigment used is a pigment prepared by oxidative polymerization of an indole compound corresponding to the formula (I): ##STR2## in which: R 1 and R 3 represent, independently of each other, a hydrogen atom or a C 1 -C 4 alkyl group; R 2 represents a hydrogen atom, a C 1 -C 4 alkyl group, a carboxyl group or a (C 1 -C 4 alkoxy)carbonyl group; R 4 and R 7 represent, independently of each other, a hydrogen atom, a hydroxyl group, a C 1 -C 4 alkyl group, an amino group, a C 1 -C 4 alkoxy group, a (C 2 -C 4 acyl)oxy group or a (C 2 -C 4 acyl)amino group; R 5 represents a hydrogen atom, a hydroxyl group, a C 1 -C 4 alkoxy group, a C 1 -C 4 alkyl group, a halogen atom, an amino group, a (C 2 -C 14 acyl)oxy group, a (C 2 -C 4 acyl)amino group or a trimethylsilyloxy group; R 6 represents a hydrogen atom, a hydroxyl group, a C 1 -C 4 alkoxy group, an amino group, a (C 2 -C 4 acyl)oxy group, a (C 2 -C 4 acyl)amino group, a trimethylsilyloxy group or a (C 2 -C 4 hydroxyalkyl)amino group; it is also possible for R 5 and R 6 to form, together with the carbon atoms to which they are attached, a carbonyldioxy ring; at least one of the radicals R 4 to R 7 represents a group OZ or NHR 8 , no more than one of the radicals R 4 to R 7 representing NHR 8 and no more than two of the radicals R 4 to R 7 representing OZ and, in the case where Z represents a hydrogen atom, the two OH groups are in positions 5 and 6; and at least one of the radicals R 4 to R 7 represents a hydrogen atom, and in the case where only one of these radicals R 4 to R 7 represents a hydrogen atom, then only one radical among R 4 to R 7 represents NHR 8 or OZ, the other radicals representing a C 1 -C 4 alkyl group; the radical R 8 of the group NHR 8 denoting a hydrogen atom, a C 2 -C 4 acyl or C 2 -C 4 hydroxyalkyl group, and the radical Z of the group OZ denoting a hydrogen atom, a C 2 -C 4 acyl group, a C 1 -C 4 alkyl group or a trimethylsilyl group, and their salts with alkali metals, alkaline-earth metals, ammonium or amines.

Claim 9

Process according to claim 7, characterized in that the indole compounds of formula (I) are chosen from: 4-hydroxyindole, 5-hydroxyindole, 6-hydroxyindole, 7-hydroxyindole, 4-hydroxy-5-methoxyindole, 4-hydroxy-5-ethoxyindole, 2-carboxy-5-hydroxyindole, 5-hydroxy-6-methoxyindole, 6-hydroxy-7-methoxyindole, 5-methoxy-6-hydroxyindole, 5,6-dihydroxyindole, N-methyl-5,6-dihydroxyindole, 2-methyl-5,6-dihydroxyindole, 3-methyl-5,6-dihydroxyindole, 2,3-dimethyl-5,6-dihydroxyindole, 2-carboxy-5,6-dihydroxyindole, 4-hydroxy-5-methylindole, 2-carboxy-6-hydroxyindole, 6-hydroxy-N-methylindole, 2-ethoxycarbonyl-5,6-dihydroxyindole, 4-hydroxy-7-methoxy-2,3-dimethylindole, 4-hydroxy-5-ethoxy-N-methylindole, 6-hydroxy-5-methoxy-2-methylindole, 6-hydroxy-5-methoxy-2,3-dimethylindole, 6-hydroxy-2-ethoxycarbonylindole, 7-hydroxy-3-methylindole, 5-hydroxy-6-ethoxy-2,3-dimethylindole, 5-hydroxy-3-methylindole, 5-acetoxy-6-hydroxyindole, 5-hydroxy-2-ethoxycarbonylindole, 6-hydroxy-2-carboxy-5-methylindole, 6-hydroxy-2-ethoxycarbonyl-5-methoxyindole, 6-β-hydroxyethylaminoindole, 4-aminoindole, 5-aminoindole, 6-aminoindole, 7-aminoindole, N-methyl-6-β-hydroxyethylaminoindole, 6-amino-2,3-dimethylindole, 6-aminoindole-2,3,4,5-tetramethylindole, 6-amino-2,3,4-trimethylindole, 6-amino-2,3,5-trimethylindole, 6-amino-2,3,6-trimethylindole, 5,6-diacetoxyindole, 5-methoxy-6-acetoxyindole, 5,6-bis(trimethylsilyloxy)indole, the phosphoric ester of 5,6-dihydroxyindole, 5,6-dibenzyloxyindole, and the addition salts of these compounds.

Claim 10

Process according to claim 4, characterized in that the dispersion containing the melanin pigment to be ground is introduced into a grinder containing beads.

Claim 11

Process according to claim 4, characterized in that a grinder containing beads using zirconium oxide beads, glass beads or sand is used.

Claim 12

Process according to claim 4, characterized in that the composition subjected to the grinding contains 5 to 50% by weight of melanin pigments relative to the total weight of the composition.

Claim 13

Process according to claim 4, characterized in that the grinding temperature is between room temperature and 110° C. depending on whether the medium used for the grinding is solid or otherwise at room temperature.

Claim 14

Process according to claim 4, characterized in that the linear or branched monoalcohols are chosen from dodecanol and oleyl alcohol; the linear or branched polyols are chosen from propylene glycol or glycerine; the cycloaliphatic alcohol is cyclohexanol; the aromatic alcohols are chosen from benzyl alcohol or phenylethyl alcohol; the esters are chosen from isopropyl myristate and palmitate, C 8 -C 12 fatty acid triglycerides, triolein, octyl stearate, fatty alcohol benzoates, pentaerythritol caprylate/caprate or pentaerythritol tetraisostearate; the silicones are polyorganosiloxanes in oil form.

Claim 15

Process according to claim 13, characterized in that the silicones are polyalkylsiloxanes, polyarylsiloxanes, polyalkylarylsiloxanes, silicone gums and resins mixed with volatile silicones, polyorganosiloxanes modified by oxyethylenated and/or oxypropylenated groups.

Claim 16

Dispersion obtained by the implementation of the process as defined in claim 4.

Claim 17

A make-up, sun care or hair coloring composition comprising the dispersion of claim 1.

Claim 18

Cosmetic composition, characterized in that it comprises, at least in part, a dispersion as defined in claim 1 in a cosmetically acceptable medium.

Claim 19

Composition according to claim 17, characterized in that it comprises melanin pigments in the form of particles, for which at least 75% of the particles have a particle size lower than 10 microns, in proportions between 0.001 and 20% by weight relative to the total weight of the composition.

Claim 20

Composition according to claim 17, intended to be used for making up skin, eyelashes and eyebrows, characterized in that it is present in solid or pasty, anhydrous or aqueous form.

Claim 21

Composition according to claim 17, intended for protecting human skin against UV rays, characterized in that it takes the form of a suspension in solvents or fatty substances, or takes the form of emulsions, ointments, gels, small solid sticks or aerosol foams.

Claim 22

Composition according to claim 17, characterized in that it contains contain fatty substances, organic solvents, silicones, thickeners, emollients, sun filters, antifoaming agents, moisturizing agents, perfumes, preservatives, antioxidizing agents, fillers, sequestering agents, treating agents, propellants and basifying or acidifying agents, or other pigments.

Claim 23

Composition according to claim 20, characterized in that it contains a nanopigment of metallic oxide chosen from the oxides of titanium, zinc, cerium or zirconium, these nanopigments having a mean diameter lower than 100 nm and being coated or non-coated.