WO2013076673A1

WO2013076673A1 - Composition of pickering emulsion type based on hydrophobic silica particles

Info

Publication number: WO2013076673A1
Application number: PCT/IB2012/056615
Authority: WO
Inventors: Isabelle Bara
Original assignee: L'oreal
Priority date: 2011-11-25
Filing date: 2012-11-22
Publication date: 2013-05-30

Abstract

The present invention relates to composition in the form of an oil-in-water emulsion, comprising, in a cosmetically acceptable medium: (i) a dispersed oily phase comprising at least one apolar hydrocarbon-based oil; (ii) a continuous aqueous-alcoholic phase comprising at least one C₁-C₄ monoalcohol; and (iii) hydrophobic silica aerogel particles.

Description

COMPOSITION OF PICKERING EMULSION TYPE BASED ON

HYDROPHOBIC SILICA PARTICLES

The present invention relates to the field of cosmetics, and especially to the field of compositions in the form of droplets in suspension in a liquid, which are used after shaking.

The invention relates more particularly to a liquid composition in the form of an oil-in-water emulsion, comprising, in a cosmetically acceptable medium:

(i) a dispersed oily phase comprising at least one apolar hydrocarbon-based oil;

(ii) a continuous aqueous phase comprising at least one C1 -C4 monoalcohol; and

(iii) hydrophobic silica aerogel particles.

Two-phase compositions which appeal to consumers on account of their esthetic nature exist currently on the market. These compositions consist of two mutually immiscible phases, which are mixed together extemporaneously by shaking before use.

Unlike the compositions of the present invention, the two phases of these compositions are two separate superposed layers of different color, not forming any particular pattern, and separated by a quite distinct interface.

Patent application FR 2 208 642 teaches the use and preparation, in general, of two-phase liquid cosmetic compositions, of Pickering emulsion type, which are appealing due to the fact that the oily phase is dispersed in the form of droplets in a homogeneous mixture between an organic liquid and water.

Finely divided solid particles are adsorbed at the interface between the oil and the homogeneous mixture, and serve to stabilize the oil droplets.

However, it is never a question in said document of compositions comprising hydrophobic particles of an aerogel material.

Patent EP 1 005 849 for its part discloses compositions of Pickering emulsion type for treating the hair or the scalp.

In general, the standard emulsions are stabilized by means of surfactants which, by virtue of their amphiphilic structure, position themselves at the interface between the lipophilic phase and the hydrophilic continuous phase, thus stabilizing the dispersed oil droplets. However, the presence of surfactants presents various drawbacks, in particular that of sometimes being poorly tolerated by certain users.

FR 2 208 642 proposes to stabilize emulsions with small, finely divided solid particles, for instance talc.

However, these emulsions have a tendency to become destabilized on storage over time. The reason for this is that sedimentation of the solid particles or even phase separation is observed, leading to an appearance that consumers find unappealing.

There is thus a need for a composition of Pickering emulsion type that has better long-term stability.

The object of the present invention is to satisfy this need.

The inventors have demonstrated, unexpectedly, in the context of the present application, that the use of particles of a hydrophobic aerogel material solves the sedimentation problem observed with solid particles.

Thus, a subject of the present invention is firstly a liquid composition in the form of an oil- in- water emulsion, comprising, in a cosmetically acceptable medium:

(ii) a continuous aqueous-alcoholic phase comprising at least one C1 -C4 monoalcohol; and

(iii) hydrophobic silica aerogel particles.

The term "cosmetically acceptable medium" means a medium that is compatible with the skin and/or its integuments or mucous membranes, that has a pleasant color, odor and feel and that does not cause any unacceptable discomfort (stinging, tautness or redness) liable to dissuade the consumer from using this composition.

The term "aqueous-alcoholic phase" means a phase comprising at least water and an organic compound comprising at least one OH function.

To the inventors' knowledge, it has never been proposed, for the purpose of solving the sedimentation problems of solid particles used in Pickering emulsions, to replace these solid particles with particles of a hydrophobic aerogel material.

Such a modification of the nature of the particles used in Pickering emulsions thus gives these emulsions improved long-term stability.

For the purposes of the present invention, the term "composition with long- term stability" means a composition that does not undergo any significant change in its structure or properties for at least one month after its manufacture and especially for at least two months after its manufacture.

Preferentially, a composition according to the invention may be chosen from a deodorant composition, a haircare composition and a fragrancing composition.

In addition, the use of particles of a hydrophobic aerogel material makes it possible to obtain transparent droplets of lipophilic dispersed phase, which may be termed as crystalline. They thus have a particular esthetic appearance, which makes them highly appealing to consumers, especially when compared with compositions of Pickering emulsion type using solid particles such as talc particles, which render the droplets opaque.

As stated previously, a composition in accordance with the invention also has the advantage of not requiring the presence of surfactants and thus of overcoming a certain number of drawbacks, such as those stated in patent application FR 2 208 642.

In certain embodiments, a composition in accordance with the invention may also be colored. In this embodiment, a composition according to the invention may comprise, either in the lipophilic dispersed phase or in the hydrophilic continuous phase, or in each of the two phases, at least one coloring agent.

In the rest of the description, (i) a colorant present in the dispersed lipophilic phase is denoted as a "first colorant" and (ii) a colorant present in the continuous hydrophilic phase is denoted as a "second colorant", including when only one from among the dispersed and continuous phases comprises a colorant.

In other embodiments, a composition according to the invention comprises at least one liposoluble first colorant in the dispersed oily phase (i) and at least one water- soluble second colorant in the continuous aqueous-alcoholic phase (ii).

Advantageously, said first and second colorants give the dispersed and continuous phases of a composition according to the invention shades that differ from each other.

Specifically, the addition of at least one colorant to each of the phases of a composition of Pickering type according to the invention so as advantageously to give these phases different shades makes it possible, after correct shaking, to obtain a third shade that is different from the two preceding ones.

The colorant(s) present, respectively, (i) in the dispersed oily phase and (ii) in the continuous aqueous-alcoholic phase thus constitute homogeneity markers that enable the user to determine simply and directly if the composition according to the invention is sufficiently homogenized to be able to be used.

For the purposes of the invention, two shades are considered as being different from each other when the difference between their respective colors can be distinguished by the user with the naked eye.

In particular, the difference between shades (ΔΕ) can be measured in the L to b colorimetric measuring system as defined according to the CIE 1976 standard.

The value of ΔΕ is calculated according to formula (I) below:

ΔΕ = V (Li-L₂)²+(ai-a₂)²+(bi-b₂)², in which:

Li, ai, bi are the CIE Lab colorimetric space coordinates of the first color to be compared, and

L₂, a₂, b₂ are the CIE Lab colorimetric space coordinates of the second color to be compared.

The compositions in accordance with the invention afford, when compared with the usual galenical forms, especially aqueous-alcoholic solutions, a substantial moisturizing effect and also better sensory effects such as a more silky and less dry feel on the skin.

The cosmetic agent(s) contained in the cosmetic compositions according to the invention may be varied.

Thus, the cosmetic agents that may be used in the compositions of the present invention may be chosen especially from fragrances, skincare and/or skin-treating active agents and haircare and/or hair-treating active agents.

The present invention is also directed toward a process for fragrancing human keratin materials and/or clothing that is in contact with said keratin materials, comprising the application to said keratin materials and/or said clothing of a composition in accordance with the invention.

The present invention is also directed toward a cosmetic process for treating and/or caring for human keratin materials, comprising the application to said keratin materials of a composition in accordance with the invention.

The term "human keratin materials" means the skin (of the body, face and around the eyes), hair, eyelashes, eyebrows, bodily hair, nails, lips or mucous membranes. The compositions in accordance with the invention may thus be readily prepared without heating or at room temperature, in contrast with the known techniques for manufacturing emulsions, which are generally prepared with heating. Mention may be made especially of the production of emulsions by simple stirring, for example using a paddle blender.

Preferentially, the composition of the invention will be in liquid form.

For the purposes of the invention, the term "liquid composition" means a composition that is not in solid form and whose viscosity, measured using a Rheomat 180 viscometer at 25°C at a spin speed of 200 rpm after 10 minutes of rotation, is less than or equal to 2 Pa.s and more preferentially ranges from 0.01 Pa.s to 0.5 Pa.s.

For the purposes of the present invention, the term "surfactant" means an amphiphilic molecule, i.e. a molecule that has two parts of different polarity, one being lipophilic (which retains fatty substances) and apolar, and the other hydrophilic (water- miscible) and polar. Thus, the solid particles in accordance with the invention are not considered as surfactants for the purposes of the present invention.

Dispersed oily phase

As indicated previously, a composition in accordance with the invention comprises a dispersed oily phase comprising at least one apolar hydrocarbon-based oil.

For the purposes of the present invention, the term "apolar oil" means an oil whose solubility parameter at 25°C, 5a, is equal to 0 (J/cm³)^1/2.

The definition and calculation of the solubility parameters in the Hansen three- dimensional solubility space are described in the article by CM. Hansen: "The three dimensional solubility parameters", J. Paint Technol. 39, 105 (1967).

According to this Hansen space:

- 5D characterizes the London dispersion forces derived from the formation of dipoles induced during molecular impacts;

- δρ characterizes the Debye interaction forces between permanent dipoles and also the Keesom interaction forces between induced dipoles and permanent dipoles;

- 5h characterizes the specific interaction forces (such as hydrogen bonding, acid/base, donor/acceptor, etc.); and

- 5a is determined by the equation: 5a = (δρ² + 5h²)½. The parameters δρ, 5h, 5D and 5a are expressed in (J/cm³)½.

An apolar oil in accordance with the invention is hydrocarbon-based.

The term "hydrocarbon-based oil" means an oil formed essentially from, or even constituted by, carbon and hydrogen atoms, and optionally oxygen and nitrogen atoms, and not containing any silicon or fluorine atoms. It may contain alcohol, ester, ether, carboxylic acid, amine and/or amide groups.

According to one embodiment, the apolar hydrocarbon-based oil according to the invention is free of heteroatoms. The term "heteroatom" means an atom other than carbon or hydrogen.

The apolar oil according to the invention may be nonvolatile.

The term "nonvolatile oil" means any oil whose vapor pressure at room temperature and atmospheric pressure is nonzero and less than 0.02 mmHg and better still less than 10^"3 mmHg.

An apolar hydrocarbon-based oil in accordance with the invention advantageously represents from 5% to 40% by weight relative to the total weight of the composition, preferably from 5% to 30% by weight and preferentially from 10% to 30% by weight relative to the total weight of the composition containing it.

According to one preferred embodiment, the apolar hydrocarbon-based oil used in the present invention is nonvolatile and may be chosen advantageously from linear or branched saturated alkanes.

An apolar hydrocarbon-based oil according to the invention may be chosen from oils whose molecular mass is between 300 and 900 g/mol and preferably between 350 and 800 g/mol.

According to one preferred embodiment, the apolar hydrocarbon-based oil is chosen from linear or branched hydrocarbons of mineral or synthetic origin, preferably from a volatile or nonvolatile liquid paraffin oil, hydrogenated isoparaffin, naphthalene oil, a totally or partially hydrogenated liquid polydecene, isoeicosane, a decene/butene copolymer, or a polybutene/polyisobutene copolymer, and mixtures thereof.

The term "hydrocarbon" means a compound consisting of carbon and hydrogen.

According to one particular embodiment, the following will preferably be used among the apolar hydrocarbon-based oils: - hydrogenated isoparaffms, for instance the hydrogenated polyisobutene sold under the name Parleam by the company Rossow, or under the name Polysynlane by Nippon Oil & Fat or Polyester Corp.;

- the C8-C9 isoparaffin sold under the name Isopar E by ExxonMobil Chemical;

- the C11-C13 isoparaffin from Exxon sold under the name Isopar L; or

- the C13-C14 isoparaffin sold under the name Isopar M by the company ExxonMobil Chemical;

- the liquid paraffins from Petro Canada: Puretol 9, or Blandol from Sonneborn, or Marcol 82 sold by ExxonMobil Chemical, and

- the plant perhydrosqualenes sold under the name Olive Squalane by SOS Corporation Alimentaria, or Vegetable Squalane by Lake Oil, or Exolive by Caroi Line Cosmetica.

The dispersed oily phase according to the invention is in the form of spheres of more or less homogeneous size, which may range between 0.5 and 20 mm, preferably between 0.5 and 10 mm and preferentially between 1 and 5 mm.

The number of oil spheres will vary as a function of the percentage of fragrance and of oil. From 1 to several million per liter of formulation may be counted as a function of their size. These spheres may be present in the upper or lower part of the composition comprising them or in both parts of the composition.

As indicated previously, a dispersed oily phase according to the invention may also comprise at least one first liposoluble coloring agent.

Such a colorant may be of natural or synthetic origin.

For the purposes of the invention, the term "liposoluble colorant" means any generally organic, natural or synthetic compound, which is soluble in an oily phase.

Examples of liposoluble colorants in accordance with the invention that may be mentioned include:

- a violet organic colorant, D&C Violet No. 2 K7014 Chemical name: Alizurol purple SS;

- a green organic colorant, D&C Green No. 6 K7016 / 90097 D&C Green 6 Chemical name: quinizarin green E SS;

- a pink organic colorant, D&C Red No. 21 K7061 / Suncroma D&C Red 21 C 14-032 Chemical name: Eosin; and - an orange vegetable colorant, Betatene 30% OLV Chemical name: Carotenoids (CI. 75130-E160 A) at 30% in olive oil.

The liposoluble colorants in accordance with the invention may also be chosen from Sudan Red, D&C Red 17, β-carotene, Sudan Brown, D&C Yellow 11, D&C Orange 5, quinoline yellow and annatto.

The dispersed oily phase according to the invention may also comprise other oils, such as silicone oils or plant oils, provided that they do not impair the stability of the composition according to the invention.

Continuous aqueous-alcoholic phase

As indicated previously, a composition in accordance with the invention comprises, in addition to a dispersed oily phase, a continuous aqueous phase comprising at least one C1-C4 monoalcohol.

A monoalcohol in accordance with the invention may preferably be chosen from linear C1-C4 hydroxyalkyls. Ethanol will be used more particularly.

Such a monoalcohol may be present in a content ranging from 50% to 90% by weight and preferably from 53% to 70% by weight relative to the total weight of the composition.

This continuous aqueous phase comprises at least water. This water is then preferably present in a content ranging from 0.5% to 10% by weight and more preferentially from 1% to 5% by weight relative to the total weight of the composition according to the invention.

As indicated previously, the continuous aqueous-alcoholic phase in accordance with the invention may also comprise at least a second liposoluble colorant. This colorant may be of synthetic or plant origin.

For the purposes of the invention, the term "water-soluble colorant" means any natural or synthetic, generally organic compound, which is soluble in an aqueous phase or in water-miscible solvents such as C1-C4 monoalcohols and which is capable of coloring.

Mention may in particular be made, as water-soluble dyes suitable for the invention, of synthetic or natural water-soluble dyes, such as, for example, FDC Red 4, DC Red 6, DC Red 22, DC Red 28, DC Red 30, DC Red 33, DC Orange 4, DC Yellow 5, DC Yellow 6, DC Yellow 8, FDC Green 3, DC Green 5, FDC Blue 1, betanin (beetroot), carmine, copper chlorophyllin, methylene blue, anthocyanins (oenocyanin, black carrot, hibiscus, elder), caramel and riboflavin.

According to one particularly preferred form of the invention, the dispersed oily phase and the continuous aqueous phase are adjusted such that the absolute value of the difference in density (Ad) between the dispersed oily phase and the continuous aqueous phase is not more than 0.05 and advantageously not more than 0.01.

Hydrophobic silica aerogel particles

A composition according to the invention also comprises hydrophobic silica aerogel particles, which are intended to stabilize the composition according to the invention by positioning themselves at the dispersed phase/continuous phase interface.

Aerogels are ultralight porous materials which were first produced by Kristler in 1932.

They are generally synthesized by a sol-gel process in a liquid medium and then dried by extraction with a supercritical fluid. The supercritical fluid most commonly used is supercritical C0₂. This type of drying makes it possible to avoid shrinkage of the pores and of the material.

Other types of drying also make it possible to obtain porous materials starting from gel, namely (i) drying by freeze drying, which consists in solidifying the gel at low temperature and in then subliming the solvent, and (ii) drying by evaporation. The materials thus obtained are referred to respectively as cryogels and xerogels. The sol-gel process and the various drying operations are described in detail in Brinker C.J. and Scherer G.W., Sol-Gel Science, New York, Academic Press, 1990.

The term "hydrophobic silica" means any silica whose surface is treated with silylating agents, for example halogenated silanes such as alkylchlorosilanes, siloxanes, in particular dimethylsiloxanes such as hexamethyldisiloxane, or silazanes, so as to functionalize the OH groups with silyl groups Si-Rn, for example trimethylsilyl groups.

Preferably, the hydrophobic aerogel particles that may be used in the present invention advantageously have a specific surface area per unit of mass (SM) ranging from 500 to 1500 m²/g, preferably from 600 to 1200 m²/g and better still from 600 to 800 m²/g and/or have an oil-absorbing capacity measured at the Wet Point ranging from 5 to 18 ml/g of particles, preferably from 6 to 15 ml/g and better still from 8 to 12 ml/g.

The oil-absorbing capacity measured at the wet point, noted Wp, corresponds to the amount of water that needs to be added to 100 g of particle in order to obtain a homogeneous paste.

It is measured according to the Wet Point method or the method for determining the oil uptake of a powder according to the principle described in standard NF T 30-022. It corresponds to the amount of oil adsorbed onto the available surface of the powder and/or absorbed by the powder by measurement of the wet point, described below:

An amount m = 2 g of powder is placed on a glass plate, and the oil (isononyl isononanoate) is then added dropwise. After addition of 4 to 5 drops of oil to the powder, mixing is carried out using a spatula, and addition of oil is continued until conglomerates of oil and powder have formed. From this point, the oil is added at the rate of one drop at a time and the mixture is subsequently triturated with the spatula. The addition of oil is stopped when a firm, smooth paste is obtained. This paste must be able to be spread over the glass plate without cracks or the formation of lumps. The volume Vs (expressed in ml) of oil used is then noted.

The oil uptake corresponds to the ratio Vs/w.

The aerogel particles of hydrophobic silica used according to the present invention are preferably aerogel particles of silylated silica (INCI name: silica silylate).

The preparation of aerogel particles of hydrophobic silica modified at the surface by silylation is further described in the document US 7 470 725.

Use will be made in particular of hydrophobic silica aerogel particles surface- modified with trimethylsilyl groups, namely trimethylsiloxyl silica particles.

The hydrophobic aerogel particles which can be used in the present invention advantageously exhibit a size, expressed as average diameter (D[0.5]), of less than 1500 μιη and preferably ranging from 1 to 30 μιη, preferably from 5 to 25 μιη, better still from 5 to 20 μιη and even better still from 5 to 15 μιη.

The specific surface per unit of weight can be determined by the nitrogen absorption method, known as the BET (Brunauer-Emmett-Teller) method, described in The Journal of the American Chemical Society, Vol. 60, page 309, February 1938 and corresponding to the international standard ISO 5794/1 (appendix D). The BET specific surface corresponds to the total specific surface of the particles under consideration.

The sizes of the aerogel particles according to the invention can be measured by static light scattering using a commercial particle size analyzer of MasterSizer 2000 type from Malvern. The data are processed on the basis of the Mie scattering theory. This theory, which is exact for isotropic particles, makes it possible to determine, in the case of non-spherical particles, an "effective" particle diameter. This theory is described in particular in the publication by Van de Hulst, H.C., "Light Scattering by Small Particles",

Chapters 9 and 10, Wiley, New York, 1957.

According to one advantageous embodiment, the hydrophobic aerogel particles used in the present invention have a specific surface area per unit of mass (SM) ranging from 600 to 800 m²/g and a size, expressed as the volume mean diameter (D[0.5]), ranging from 5 to 20 μιη and better still from 5 to 15 μιη.

According to one preferred embodiment, VM-2270 will more particularly be used, the particles of which have a mean size ranging from 5 to 15 microns and a specific surface area per unit of the mass ranging from 600 to 800 m²/g.

The hydrophobic aerogel particles used in the present invention may advantageously have a tamped density p ranging from 0.04 g/cm³ to 0.10 g/cm³ and preferably from 0.05 g/cm³ to 0.08 g/cm³.

In the context of the present invention, this density can be assessed according to the following protocol, known as packed density protocol:

40 g of powder are poured into a graduated measuring cylinder and then the measuring cylinder is placed on a Stav 2003 device from Stampf Volumeter. The measuring cylinder is subsequently subjected to a series of 2500 packing actions (this operation is repeated until the difference in volume between two consecutive tests is less than 2%) and then the final volume Vf of packed powder is measured directly on the measuring cylinder.

The tamped density is determined by the ratio: mass m/Vf, in this instance 40/Vf (Vf being expressed in cm³ and m in g).

According to one embodiment, the hydrophobic aerogel particles used in the present invention have a specific surface area per unit of volume SV ranging from 5 to 60 m 2 /cm 3 , preferably from 10 to 50 m 2 /cm 3 and better still from 15 to 40 m 2 /cm 3. The specific surface per unit of volume is given by the relationship:

SV = SM*p where p is the tamped density expressed in g/cm³ and SM is the specific surface area per unit of mass expressed in m²/g, as defined above. According to one preferred embodiment, the hydrophobic aerogel particles according to the invention have a specific surface area per unit of mass (SM) ranging from 500 to 1500 m²/g, preferably from 600 to 1200 m²/g and better still from 600 to 800 m²/g, a size expressed as the mean diameter (D[0,5]) ranging from 1 to 30 μιη and/or an oil- absorbing capacity measured at the Wet Point ranging from 5 to 18 ml/g of particles, preferably from 6 to 15 ml/g and better still from 8 to 12 ml/g.

As hydrophobic silica aerogels that may be used in the invention, examples that may be mentioned include the aerogel sold under the name VM-2260 (INCI name: Silica silylate), by the company Dow Corning, the particles of which have an average size of about 1000 microns and a specific surface area per unit of mass ranging from 600 to 800 m²/g.

Mention may also be made of the aerogels sold by Cabot under the references Aerogel TLD 201, Aerogel OGD 201 and Aerogel TLD 203, Enova Aerogel MT 1 100 and Enova Aerogel MT 1200.

Use will be made more particularly of the aerogel sold under the name VM- 2270 (INCI name: Silica silylate), by the company Dow Corning, the particles of which have an average size ranging from 5 to 15 microns and a specific surface area per unit of mass ranging from 600 to 800 m²/g.

The hydrophobic silica aerogel particles may be used in a content preferably of between 0.05% and 5% by weight, more preferentially between 0.1% and 2% by weight and even more preferentially between 0.1% and 1% by weight relative to the total weight of the composition containing them.

Cosmetic agents

The composition may comprise at least one or more additional cosmetic agent(s). The additional cosmetic agent(s) contained in the cosmetic compositions according to the invention are varied.

Said cosmetic agents especially include fragrances, skincare and/or skin- treating active agents and haircare and/or hair-treating active agents.

The cosmetic active agent(s) according to the invention may be chosen from:

- antiwrinkle agents,

- moisturizers,

- free-radical scavengers,

- agents acting on the capillary circulation,

- muscle relaxants,

- calmatives such as a-bisabolol, allantoin and Aloe vera, and

- mixtures thereof.

Mention may also be made of emollients or softeners such as sweet almond oil, apricot kernel oil, vitamins, essential fatty acids, insect repellents, propellants, peptizers, UV-screening agents, stabilizers or preserving agents, gellants or thickeners, nacres or glitter flakes, and mixtures thereof.

Obviously, the additional cosmetic agents that may be present in a composition in accordance with the invention must not impair the advantageous properties indicated previously.

These cosmetic agents may be present either in the dispersed phase or in the continuous phase of a composition in accordance with the invention. Thus, the hydrophilic or water-soluble agents will be present in the continuous phase, while the lipophilic or liposoluble agents will be present in the dispersed phase.

1. Fragrancing substances

A composition in accordance with the invention may also comprise at least one fragrancing substance, or perfume.

The term "fragrancing substance" means any perfume or aroma capable of giving off a pleasant odor.

Perfumes are compositions especially containing the starting materials described in S. Arctander, Perfume and Flavor Chemicals (Montclair, N.J., 1969), in S. Arctander, Perfume and Flavor Materials of Natural Origin (Elizabeth, N.J., 1960) and in Flavor and Fragrance Materials - 1991, Allured Publishing Co., Wheaton, III.

They may also be natural products, for instance essential oils, absolutes, resinoids, resins, concretes, and/or synthetic products (terpene or sesquiterpene hydrocarbons, alcohols, phenols, aldehydes, ketones, ethers, acids, esters, nitriles or peroxides, which may be saturated or unsaturated, and aliphatic or cyclic).

According to the definition given in international standard ISO 9235 and adopted by the Commission of the European Pharmacopoeia, an essential oil is an odorous product generally of complex composition, obtained from a botanically defined plant raw material, either by steam entrainment, or by dry distillation, or via an appropriate mechanical process without heating (cold pressing). The essential oil is usually separated from the aqueous phase via a physical process that does not result in any significant change in the composition. Physicochemical characteristics

Essential oils are generally volatile and liquid at room temperature, which distinguishes them from "set" oils. They are more or less colored and their density is generally less than that of water.

They have a high refractive index and most of them deflect polarized light. They are liposoluble and soluble in the usual organic solvents, entrainable with steam, and very sparingly soluble in water.

Among the essential oils that may be used according to the invention, mention may be made of those obtained from plants belonging to the following botanical families:

Abietaceae or Pinaceae: conifers; Amaryllidaceae; Anacardaceae; Anonaceae: ylang ylang; Apiaceae (for example Umbelliferae): dill, angelica, coriander, sea fennel, carrot, parsley; Araceae; Aristolochiaceae; Asteraceae: yarrow, artemisia, camomile, helichrysum; Betulaceae; Brassicaceae; Burseraceae: frankincense; Carophyllaceae; Canellaceae; Cesalpiniaceae: copaifera (copaiba balsam); Chenopodaceae; Cistaceae: rock rose; Cyperaceae; Dipterocarpaceae; Ericaceae: gaultheria (wintergreen); Euphorbiaceae; Fabaceae; Geraniaceae: geranium; Guttiferae; Hamamelidaceae; Hernandiaceae; Hypericaceae: St-John's wort; Iridaceae; Juglandaceae; Lamiaceae: thyme, oregano, monarda, savory, basil, marjorams, mints, patchouli, lavenders, sages, catnip, rosemary, hyssop, balm; Lauraceae: ravensara, sweet bay, rosewood, cinnamon, litsea; Liliaceae: garlic; Magnoliaceae: magnolia; Malvaceae; Meliaceae; Monimiaceae; Moraceae: hemp, hop; Myricaceae; Myristicaceae: nutmeg; Myrtaceae: eucalyptus, tea tree, paperbark tree, cajuput, backhousia, clove, myrtle; Oleaceae; Piperaceae: pepper; Pittosporaceae; Poaceae: lemon balm, lemongrass, vetiver; Polygonaceae; Renonculaceae; Rosaceae: roses; Rubiaceae; Rutaceae: all citrus plants; Salicaceae; Santalaceae: sandalwood; Saxifragaceae; Schisandraceae; Styracaceae: benjoin; Thymelaceae: agar wood; Tilliaceae; Valerianaceae: valerian, spikenard; Verbenaceae: lantana, verbena; Violaceae; Zingiberaceae: galangal, turmeric, cardamom, ginger; Zygophyllaceae.

Mention may also be made of the essential oils extracted from flowers (lily, lavender, rose, jasmine, ylang ylang, neroli), from stems and leaves (patchouli, geranium, petitgrain), from fruit (coriander, aniseed, cumin, juniper), from fruit peel (bergamot, lemon, orange), from roots (angelica, celery, cardamom, iris, rattan palm, ginger), from wood (pinewood, sandalwood, gaiac wood, rose of cedar, camphor), from grasses and gramineae (tarragon, rosemary, basil, lemongrass, sage, thyme), from needles and branches (spruce, fir, pine, dwarf pine) and from resins and balms (galbanum, elemi, benjoin, myrrh, olibanum, opopanax).

Examples of fragrancing substances are especially: geraniol, geranyl acetate, farnesol, borneol, bornyl acetate, linolool, linalyl acetate, linalyl propionate, linalyl butyrate, tetrahydrolinolool, citronellol, citronellyl acetate, citronellyl formate, citronellyl propionate, dihydromyrcenol, dihydromyrcenyl acetate, tetrahydromyrcenol, terpineol, terpinyl acetate, nopol, nopyl acetate, nerol, neryl acetate, 2-phenylethanol, 2-phenylethyl acetate, benzyl alcohol, benzyl acetate, benzyl salicylate, styrallyl acetate, benzyl benzoate, amyl salicylate, dimethylbenzylcarbinol, trichloromethylphenylcarbinyl acetate, p-tert- butylcyclohexyl acetate, isononyl acetate, vetiveryl acetate, vetiverol, a- hexylcinnamaldehyde, 2-methyl-3 -(p-tert-butylphenyl)propanal, 2-methyl-3 -(p- isopropylphenyl)propanal, 3-(p-tert-butylphenyl)propanal, 2,4-dimethylcyclohex-3- enylcarboxaldehyde, tricyclodecenyl acetate, tricyclodecenyl propionate, 4-(4-hydroxy-4- methylpentyl)-3 -cyclohexenecarboxaldehyde, 4-(4-methyl-3 -pentenyl)-3 - cyclohexenecarboxaldehyde, 4-acetoxy-3-pentyltetrahydropyran, 3-carboxymethyl-2- pentylcyclopentane, 2-n-4-heptylcyclopentanone, 3-methyl-2-pentyl-2-cyclopentenone, menthone, carvone, tagetone, geranylacetone, n-decanal, n-dodecanal, 9-decen-l-ol, phenoxy ethyl isobutyrate, phenylacetaldehyde dimethyl acetal, phenylacetaldehyde diethyl acetal, geranonitrile, citronellonitrile, cedryl acetate, 3-isocamphylcyclohexanol, cedryl methyl ether, isolongifolanone, aubepinonitrile, aubepine, heliotropin, coumarin, eugenol, vanillin, diphenyl ether, citral, citronellal, hydroxycitronellal, damascone, ionones, methylionones, isomethylionones, solanone, irones, cis-3-hexenol and esters thereof, musk-indans, musk-tetralins, musk-isochromans, macrocyclic ketones, musk- macro lactones, aliphatic musks, ethylene brassylate and rose essence, and mixtures thereof.

According to one preferred embodiment of the invention, a mixture of different fragrancing substances that generate in common a note that is pleasant to the user is used.

The fragrancing substances will preferably be chosen such that they produce notes (head, heart and base) in the following families: citrine, aromatic, floral, spicy, woody, gourmand, chypre, fougere, leathery, musk.

The compositions of the invention may thus contain a concentration of less than or equal to 30% by weight, in particular from 1% to 25% by weight and preferably from 3% to 15% by weight of fragrancing substance(s) relative to the total weight of the composition comprising them.

According to one particular embodiment, when a composition according to the invention comprises at least 1% by weight of fragrancing substance(s) relative to the total weight of the composition, then the composition preferably also comprises at least one polyalkylene glycol, especially as defined below.

2. Polyalkylene glycol

A composition in accordance with the invention may also comprise at least one polyalkylene glycol.

The presence of such a compound in the fragrancing compositions in accordance with the invention advantageously makes it possible to incorporate an amount of greater than or equal to 1% by weight of fragrancing substances into a composition of Pickering type in accordance with the invention, without observing any sedimentation and/or phase separation generally observed when the content of fragrancing substances reaches such proportions in such compositions.

According to one particular embodiment, a polyalkylene glycol in accordance with the invention may be of formula (I) below: H-[0-R-]_n-OH (I),

in which

- R represents a linear or branched alkyl group containing from 1 to 4 carbon atoms, and

- n is an integer ranging from 4 to 200 and advantageously from 4 to 40.

According to one particular embodiment, n is an integer ranging from 4 to 20 and advantageously from 6 to 10.

According to one particular embodiment, a polyalkylene glycol in accordance with the invention is a polyethylene glycol.

Thus, according to one preferred embodiment, a polyalkylene glycol in accordance with the invention is a polyethylene glycol with n being an integer ranging from 4 to 20 and advantageously from 6 to 10.

According to one preferred embodiment, a polyalkylene glycol in accordance with the invention may be chosen from PEG-80E such as the product sold under the trade name Polyethylene Glycol 400 DUB PEG-8 from the company Stearineries Dubois or under the trade name Polyglycol 400 from the company Clariant, or alternatively PEG 60E sold under the trade name Carbowax PEG-300 from the company Dow chemical.

The polyalkylene glycol(s) are preferably present in the composition in concentrations ranging from 0.1% to 3% and more preferentially from 0.5% to 2% by weight relative to the total weight of the composition.

According to one preferred embodiment, a composition according to the invention comprises at least 1% by weight, relative to the total weight of the composition, of at least one fragrancing substance and at least one polyalkylene glycol, preferably of formula (I) below:

H-[0-R-]_n-OH (I),

in which

- n is an integer ranging from 4 to 200, advantageously from 4 to 40, preferably from 4 to 20 and preferentially from 6 to 10,

3. Deodorant

A composition in accordance with the invention may also comprise at least one deodorant. Thus, according to one embodiment, a composition according to the invention may be a deodorant composition.

The deodorants in accordance with the invention may be bacteriostatic agents or bactericidal agents that act on the armpit odor microorganisms, such as 2,4,4'-trichloro- 2'-hydroxydiphenyl ether (©Triclosan), 2,4-dichloro-2'-hydroxydiphenyl ether, 3',4',5'- trichlorosalicylanilide, l-(3',4'-dichlorophenyl)-3-(4'-chlorophenyl)urea (©Triclocarban) or 3,7,1 l-trimethyldodeca-2,5,10-trienol (©Farnesol).

They may also be chosen from quaternary ammonium salts such as cetyltrimethylammonium salts, cetylpyridinium salts, DPTA (1,3- diaminopropanetetraacetic acid), 1,2-decanediol (Symclariol from the company Symrise), glycerol derivatives, for instance caprylic/capric glycerides (Capmul MCM from Abitec), glyceryl caprylate or caprate (Dermosoft GMCY and Dermosoft GMC, respectively from Straetmans), Polyglyceryl-2 caprate (Dermosoft DGMC from Straetmans), and biguanide derivatives, for instance polyhexamethylene biguanide salts, chlorhexidine and salts thereof, and 4-phenyl-4,4-dimethyl-2-butanol (Symdeo MPP from Symrise).

Among the deodorants in accordance with the invention, mention may also be made of zinc salts, for instance zinc salicylate, zinc gluconate, zinc pidolate; zinc sulfate, zinc chloride, zinc lactate, zinc phenolsulfonate; salicylic acid and derivatives thereof such as 5-n-octanoylsalicylic acid.

The deodorants according to the invention may be odor absorbers such as zinc ricinoleate, sodium bicarbonate; metallic or non-metallic zeolites, cyclodextrins and alum.

They may also be a chelating agent such as Dissolvine GL-47-S from Akzo Nobel, EDTA; DPTA.

It may also be a polyol such as glycerol or propane- 1,3-diol (Zemea Propanediol sold by Dupont Tate and Lyle BioProducts), or an enzyme inhibitor such as triethyl citrate.

In the event of incompatibility or to stabilize them, some of the agents mentioned above may be incorporated into spherules, especially ionic or nonionic vesicles, and/or particles (capsules and/or spheres).

The deodorants may preferably be present in the compositions according to the invention in weight concentrations ranging from 0.01% to 15% by weight relative to the total weight of the composition. Obviously, the deodorants that may be present in a composition in accordance with the invention must not impair the advantageous properties of the composition indicated previously.

Thus, despite the presence of deodorants, a composition according to the invention has a dispersed phase and a continuous phase as defined previously, each advantageously possibly having a different shade.

In addition, when the composition is shaken, it then takes on a new shade, which is different from those of the dispersed and continuous phases at rest, when the agitation has been efficient enough for the composition to be able to be used.

4. Haircare agent

According to one embodiment, a composition according to the invention may be a haircare composition, more particularly intended for caring for the hair and/or the scalp.

Thus, an emulsion in accordance with the invention may comprise at least one haircare active agent chosen from:

- antiseborrhoeic agents;

- agents for combating desquamative states of the scalp;

- active agents for stimulating hair growth and/or for promoting the slowing- down of hair loss;

- antibacterial agents;

- calcium antagonists;

- antiandrogenic agents;

- steroidal or nonsteroidal 5-a-reductase inhibitors;

- ATP-dependent potassium channel agonists;

- plant extracts with propigmenting activity.

Obviously, the haircare agents that may be present in a composition in accordance with the invention must not impair the advantageous properties indicated previously in the present text. 5. Water-soluble metal salt

A composition in accordance with the invention may also comprise at least one water-soluble metal salt.

The term "water-soluble metal salt" means any cosmetic or dermatological metal salt that can be completely dissolved in molecular form in a liquid aqueous phase comprising water or a mixture of water/Ci-C4 monoalcohol.

According to the present invention, the term "metal salt" means a salt of a metal, i.e. of a simple substance that is capable of releasing simple cations (Dictionnaire de la Chimie et de ses Applications, Duval & Duval, 3rd Edition, 1978, Technique et Documentation) .

The water-soluble metal salts are more particularly chosen from water-soluble salts of alkali metals or of alkaline-earth metals.

As water-soluble salts of alkali metals that are useful according to the invention, mention may be made in particular of sodium or potassium salts.

As water-soluble salts of alkaline-earth metals that are useful according to the invention, mention may be made in particular of magnesium or calcium salts.

These salts may be, for example, carbonates, bicarbonates, sulfates, chlorides, nitrates, acetates or hydroxides, and also salts of a-hydroxy acids or salts of fruit acids (citrate, tartrate, lactate or malate), or alternatively salts of amino acids (aspartate, arginate, glucocholate or fumarate).

Preferably, a salt according to the invention is chosen from calcium chloride and sodium chloride. It is preferably calcium chloride.

The water-soluble metal salts in accordance with the invention may be present in a content of between 0% and 5% by weight and preferably between 0.2% and 1% by weight relative to the total weight of the composition.

Conditioning

A composition according to the invention may constitute a fragrancing composition, a deodorant composition, a composition for caring for and/or treating keratin materials and may especially be in the form of a deodorant product in spray or aerosol form (body mist or body splash), an eau fraiche, an eau de toilette, an eau de parfum or an aftershave lotion.

Preferably, it constitutes a deodorant composition, a haircare composition or a fragrancing composition. A composition in accordance with the invention may, for example, be conditioned in a bottle.

A composition of the invention may be dispensed by means of various systems that are well known to those skilled in the art, such as sprayers with or without pressurized gas, or alternatively roll-on applicators.

A composition according to the invention may be manufactured via the known processes generally used in the field of deodorant, haircare or fragrancing formulations.

The compositions according to the invention may also be applied in the form of fine particles by means of pressurization devices. The devices in accordance with the invention are well known to those skilled in the art and comprise non-aerosol pumps or "atomizers", piezoelectric devices, aerosol containers comprising a propellant and also aerosol pumps using compressed air as propellant. These devices are especially described in patents US 4 077 441 and US 4 850 517 (which form an integral part of the content of the description), more particularly relating to fragrancing compositions.

The compositions conditioned as aerosols in accordance with the invention generally contain conventional propellants, for instance dimethyl ether, isobutane, n- butane, propane or trichlorof uoromethane.

As indicated previously, a composition of Pickering emulsion type in accordance with the invention must be shaken before use so as to make the composition perfectly homogeneous, this being demonstrated by the appearance of a new shade, which is different from those of the dispersed and continuous phases, throughout the composition.

In the description and the examples that follow, unless otherwise mentioned, the percentages are weight percentages and the ranges of values written in the form "between ... and ..." include the stated lower and upper limits. The ingredients are mixed, before being formed, in the order and under conditions that may readily be determined by a person skilled in the art.

The examples below are presented as non-limiting illustrations of the field the invention. EXAMPLES Example 1: Stable composition containing 1% fragrance

* the fragrance used comprises 40% hedione, 15% geraniol, 22%> linalyl acetate, 2%> ethylvanillin, 1%> Ambrox DL, 10%o rose essence, 5%> citral and 5%> patchoulol.

** VM 2270 Aerogel sold by the company Dow Corning.

The difference in density between the two phases of the composition is 0.00635.

The composition thus obtained consists of a two-phase solution containing orange-colored transparent droplets of crystalline appearance suspended in a perfectly clear pink-colored liquid.

The droplets are distributed at the bottom of the bottle comprising the composition, their size being from 1 to 5 mm.

After moderate manual shaking for 5 seconds, the orange/pink two-colored composition becomes readily homogenized as a pinkish apricot solution, and may be vaporized uniformly, for example using a standard pump-action bottle. The result on the skin is a fragranced fluid deposit, which feels fresh on application, and after drying has a silky feel on the skin.

Once the bottle has been left to stand, the original two-phase distribution of the composition is regained after 5 minutes.

After two months, the appearance and the organoleptic qualities of the product are unchanged, both at room temperature and at 37°C. A total absence of deposit of particles at the bottom of the container after two months is also noted, both at room temperature and at 45 °C.

Example 2: Stable composition containing 2% fragrance

* the fragrance used comprises 40% hedione, 15% geraniol, 22% linalyl acetate, 2% ethylvanillin, 1% Ambrox DL, 10% rose essence, 5%> citral and 5%> patchoulol.

** VM 2270 Aerogel sold by the company Dow Corning. The difference in density between the two phases of the composition is

0.00033.

The composition thus obtained consists of a two-phase solution containing perfectly transparent colorless droplets suspended in a perfectly clear pink-colored liquid.

The droplets are distributed at the bottom and top of the bottle comprising the composition, their heterogeneous size being from 0.5 to 10 mm. After moderate manual shaking for 5 seconds, the composition becomes readily homogenized as a uniform solution, and may be vaporized, for example, using a standard pump-action bottle.

The result on the skin is a fragranced fluid deposit, which feels fresh on application, and after drying has a silky feel on the skin.

After two months, the appearance and the organoleptic qualities of the product are unchanged, both at room temperature and at 37°C.

Claims

1. A liquid composition in the form of an oil-in-water emulsion comprising, in a cosmetically acceptable medium:

(ii) a continuous aqueous phase comprising at least one C₁-C4 monoalcohol; and

(iii) hydrophobic silica aerogel particles.

2. The composition as claimed in claim 1, in which the hydrophobic aerogel particles according to the invention have a specific surface area per unit of mass (SM) ranging from

500 to 1500 m²/g, preferably from 600 to 1200 m²/g and better still from 600 to 800 m²/g, and a size expressed as the mean diameter (D[0.5]) ranging from 1 to 30 μιη and/or an oil- absorbing capacity measured at the Wet Point ranging from 5 to 18 ml/g of particles, preferably from 6 to 15 ml/g and better still from 8 to 12 ml/g.

3. The composition as claimed in claim 1 or 2, characterized in that the hydrophobic silica aerogel particles have a size, expressed as the volume mean diameter, ranging from 5 to 25 μιη, better still from 5 to 20 μιη and even better still from 5 to 15 μιη.

4. The composition as claimed in one of claims 1 to 3, characterized in that the hydrophobic silica aerogel particles are trimethylsiloxyl silica particles.

5. The composition as claimed in any one of claims 1 to 4, characterized in that the hydrophobic silica aerogel particles have a tamped density p ranging from 0.04 g/cm³ to 0.10 g/cm³ and preferably from 0.05 g/cm³ to 0.08 g/cm³.

6. The composition as claimed in any one of claims 1 to 5, characterized in that the hydrophobic silica aerogel particles have a specific surface area per unit volume SV ranging from 5 to 60 m²/cm³, preferably from 10 to 50 m²/cm³ and better still from 15 to 40 m²/cm³.

7. The composition as claimed in any one of the preceding claims, characterized in that it comprises at least one cosmetic agent chosen from fragrances, skincare and/or skin-treating active agents and hair care and/or hair-treating active agents.

8. The composition as claimed in any one of the preceding claims, characterized in that it also comprises at least 1% by weight, relative to the total weight of the composition, of at least one fragrancing substance and at least one polyalkylene glycol, preferably of formula (I) below:

H-[0-R-]_n-OH (I),

in which

9. The composition as claimed in any one of the preceding claims, in which the polyalkylene glycol(s) are preferably present in the composition in concentrations ranging from 0.1% to 3% and more preferentially from 0.5% to 2% by weight relative to the total weight of the composition.

10. The composition as claimed in any one of the preceding claims, characterized in that the apolar hydrocarbon-based oil is chosen from linear or branched hydrocarbons of mineral or synthetic origin, in particular chosen from a volatile or nonvolatile liquid paraffin oil, hydrogenated isoparaffin, naphthalene oil, a totally or partially hydrogenated liquid polydecene, isoeicosane, a decene/butene copolymer, or a polybutene/polyisobutene copolymer, and mixtures thereof.

11. The composition as claimed in any one of the preceding claims, characterized in that said C1-C4 monoalcohol is chosen from linear C1-C4 hydroxyalkyls, advantageously ethanol.

12. The composition as claimed in any one of the preceding claims, characterized in that it comprises a water-soluble metal salt.

13. The composition as claimed in any one of the preceding claims, characterized in that the absolute value of the difference in density (Ad) between the dispersed oily phase and the continuous aqueous phase is not more than 0.05 and advantageously not more than 0.01.

14. The composition as claimed in any one of the preceding claims, characterized in that it comprises at least one liposoluble first colorant in the dispersed oily phase (i) and at least one water-soluble second colorant in the continuous aqueous-alcoholic phase (ii).

15. The composition as claimed in claim 14, characterized in that said first and second colorants give the dispersed and continuous phases of said compositions different shades.

16. A process for fragrancing human keratin materials and/or clothing that is in contact with said keratin materials, comprising the application to said keratin materials and/or said clothing of a composition according to any one of the preceding claims.

17. A cosmetic process for treating and/or caring for human keratin materials, comprising the application to said keratin materials of a composition as claimed in any one of claims 1 to 15.