EP1480596A1

EP1480596A1 - Cosmetic formulation comprising at least two active substances in a multiple emulsion optionally mixed with a single emulsion

Info

Publication number: EP1480596A1
Application number: EP02714272A
Authority: EP
Inventors: Hélène LANNIBOIS-DREAN; Jean-Marc Ricca
Original assignee: Rhodia Chimie SAS
Current assignee: Rhodia Chimie SAS
Priority date: 2002-03-04
Filing date: 2002-03-04
Publication date: 2004-12-01
Also published as: WO2003074010A1; US20050169946A1; AU2002246190A1; JP2005525359A

Abstract

The invention concerns a cosmetic and/or dermatological composition comprising at least two active substances in a multiple emulsion consisting of an internal aqueous phase dispersed in an internal oily phase, the whole being dispersed in an external aqueous phase, the multiple emulsion being optionally mixed with a single emulsion consisting of an external oily phase dispersed in an external aqueous phase: the internal oily phase comprising at least one nonionic surfactant and/or at least one amphiphilic polymer and optionally at least one hydrophobic active substance; the external aqueous phase comprising at least one nonionic surfactant and/or at least one nonionic amphiphilic polymer optionally associated with at least one anionic amphiphilic polymer or comprising at least one anionic amphiphilic polymer optionally associated with at least one anionic surfactant; at least one hydrophilic active substance being present in the internal aqueous phase; and at least one active substance being present in soluble form, solubilized or in the form of a solid dispersed in the external aqueous phase, or being present in the external oily phase.

Description

COSMETIC FORMULATION COMPRISING AT LEAST TWO MATERIALS

ACTIVE IN A MULTIPLE EMULSION POSSIBLY

MIXED WITH A SINGLE EMULSION

The present invention relates to cosmetic and / or dermatological formulations comprising at least two active materials in a multiple emulsion of water in oil in water type, optionally mixed with a simple emulsion of oil in water type.

It is increasingly proposed to consumers, to have with a same formulation, a plurality of simultaneous and / or successive effects. Such performances are obtained by combining in the formulation several active substances.

This does not pose any major difficulty if the active materials are compatible with each other as well as with the medium of the formulation in which they are introduced.

In the event of incompatibility, it was then envisaged to encapsulate one of the active materials in order to isolate it from the medium and / or from the other active materials, or else to delay the effect of said encapsulated active material; the encapsulated material is then dispersed in the medium. As an example of a solution of this type, perfumes have been encapsulated in polymeric latexes. However, even if these methods bring real advantages, they are nevertheless limited to particular active ingredients. Indeed, these methods are difficult to apply to the encapsulation of hydrophilic active materials. In addition, if the active material is solid, it is necessary to find a diluent which is a swelling compound of said latex without dissolving it. Needless to say, with applications in the field of cosmetics, this choice is made all the more difficult since the diluent likely to be retained must be approved in this field. As can be seen, there is at present no satisfactory, simple and effective means for using at least two active materials which it is desired to isolate from each other and / or from the medium in which they are introduced.

These and other objects are achieved by the present invention which therefore consists of a cosmetic and / or dermatological formulation comprising at least two active materials in a multiple emulsion consisting of an internal aqueous phase dispersed in an internal oily phase, all being dispersed in an external aqueous phase; the multiple emulsion being optionally mixed with a simple emulsion consisting of an external oily phase dispersed in an external aqueous phase: α the internal oily phase comprising at least one nonionic surfactant and / or at least one amphiphilic polymer and optionally at least one hydrophobic active ingredient; ^π the external aqueous phase comprising at least one nonionic surfactant and / or at least one nonionic amphiphilic polymer optionally associated with at least one anionic amphiphilic polymer or comprising at least one anionic amphiphilic polymer optionally associated with at least one anionic surfactant; π at least one hydrophilic active material found in the internal aqueous phase; and Q at least one active ingredient which is in soluble, solubilized form or in the form of a solid dispersed in the external aqueous phase, or which is in the external oily phase.

It is indicated that in the description which follows, the term mixed emulsion will denote either the multiple emulsion or the multiple emulsion mixed with the single emulsion. Thus, the mixed emulsion used in the composition of cosmetic and / or dermatological formulations has the advantage of being easy to prepare and to implement, without requiring significant investment.

It also makes it possible to isolate any type of active material, liquid or solid, hydrophobic or hydrophilic.

The mixed emulsion is very particularly suitable when using two active materials, advantageously incompatible, one hydrophilic, the other hydrophobic; the first being introduced into the internal aqueous phase and the second into the external oily phase. In this way, the two active materials are isolated from one another in the mixed emulsion.

In addition, a delay effect can be observed, during the application of the formulation, of the least available active material, for example that present in the internal aqueous phase of the mixed emulsion.

However, other objects and advantages will appear more clearly on reading the description and the example which will follow.

In the description, the term polymer designates both homopolymers and copolymers. For reasons of convenience in the description of the invention, the inverse emulsion of the multiple emulsion, and its method of preparation will first be detailed.

The reverse emulsion therefore consists of a water-in-oil emulsion, consisting of an internal aqueous phase and an internal oily phase.

The internal oily phase comprises at least one organic oil, of animal or vegetable, or mineral origin, as well as waxes from the same origins, or their mixtures.

Preferably, an oily phase is used which is fluid under the conditions for preparing the reverse emulsion. The compound used as the oily phase is preferably chosen from the compounds whose solubility in water does not exceed 10% by weight at 25 ° C.

As organic oils of animal origin, mention may be made, among others, of sperm whale oil, whale oil, seal oil, sardine oil, herring oil, shark oil, Cod liver oil ; pork and mutton fats (tallow).

As waxes of animal origin, mention may be made of beeswax.

As examples of organic oils of vegetable origin, there may be mentioned, among others, rapeseed oil, sunflower oil, peanut oil, olive oil, oil nuts, corn oil, soybean oil, linseed oil, hemp oil, grape seed oil, coconut oil, palm oil, oil cottonseed, babassu oil, jojoba oil, sesame oil, castor oil.

As waxes of vegetable origin, mention may be made of carnauba wax.

With regard to mineral oils, mention may be made, inter alia, of naphthenic and paraffinic oils (petrolatum). Paraffinic waxes can likewise be suitable for the preparation of the emulsion.

The products derived from the alcoholysis of the abovementioned oils can also be used.

It would not go beyond the scope of the present invention to use, as internal oily phase, at least one fatty acid, saturated or not, at least one fatty acid ester, saturated or not, at least one fatty alcohol, saturated or not, or mixtures thereof. More particularly, said acids, esters or alcohols comprise at least one hydrocarbon radical having from 10 to 40 carbon atoms, more particularly 18 to 40 carbon atoms, and can comprise one or more carbon-carbon double bonds, conjugated or not. Furthermore, the acids, esters or alcohols can comprise one or more hydroxyl groups. As examples of saturated fatty acids, mention may be made of palmitic, stearic and behenic acids.

As examples of unsaturated fatty acids, there may be mentioned myristoleic, palmitoleic, oleic, erucic, linoleic, linolenic, arachidonic, ricinoleic acids, as well as their mixtures. As fatty acid esters, there may be mentioned the esters of the acids previously listed, for which the part deriving from the alcohol comprises 1 to 6 carbon atoms, such as the methyl, ethyl, propyl and isopropyl esters. , etc.

As an example of alcohols, mention may be made of those corresponding to the abovementioned acids.

It is likewise conceivable to use the esters of the abovementioned acids and of polyols, such as for example glycerol, polyglycerol (such as for example polyricinoleate of polyglycerol), glycol, propylene glycol, ethylene glycol, polyethylene glycol, polypropylene glycol, neopentylglycol (such as neopentylglycol hydroxypivalate), pentaerythritol, dipentaerythritol, trimethylolpropane, sorbitol, mannitol, xylitol, mesoerythritol.

The internal oily phase can likewise be chosen from essential oils, mono-, di- and tri-glycerides, as well as silicone oils. It can comprise at least one hydrophobic active material, as soon as it is compatible with the hydrophilic active material present in the internal aqueous phase and, if it is present, in the external aqueous phase; phases which will be described later.

Said hydrophobic active materials are in liquid form, dissolved in an organic solvent, or also in the form of a divided solid dispersed in said phase.

More particularly, the active ingredients are such that their solubility in water does not exceed 10% by weight, at 25 ° C.

Active materials whose melting point is less than or equal to 100 ° C., more particularly less than or equal to 80 ° C., can likewise be used.

By way of examples of active materials which can be used in the field of cosmetics, mention may be made of silicone oils belonging for example to the family of dimethicones; lipophilic vitamins, such as vitamin A and its derivatives, in particular its esters such as acetate, palmitate, propionate, vitamin B2, pantothenic acid, vitamin D and vitamin E; mono-, di- and triglycerides; bactericides; UV absorbing agents, such as aminobenzoate derivatives of the PABA and PARA type, salicylates, cinnamates, anthranilates, dibenzoylmethanes, camphor derivatives and their mixtures.

Anti-aging agents can also be used. As examples of such agents, mention may be made in particular of retinoids, fat-soluble vitamins, derivatives of vitamin C such as esters, in particular acetate, propionate, palmitate; ceramides, pseudoceramides, phospholipids, fatty acids, fatty alcohols, cholesterol, sterols and their mixtures. As preferred fatty acids and alcohols, mention may more particularly be made of those having linear or branched alkyl chains containing from 12 to 20 carbon atoms. It can in particular be linoleic acid.

It is likewise possible to use anti-cellulite agents, such as in particular isobutylmethylxanthine and theophyline; as well as anti-acne agents, such as, for example, resorcinol, resorcinol acetate, benzoyl peroxide and many natural compounds.

Aromas, perfumes, essential oils, essences, can also be used as a hydrophobic active material. By way of example, mention may be made of oils and / or essences of mint, spearmint, peppermint, menthol, vanilla, cinnamon, bay leaf, anise, eucalyptus, thyme, sage, cedar leaf, nutmeg, citrus (lemon, lime, grapefruit, orange), fruit (apple, pear, peach , cherry, plum, strawberry, raspberry, apricot, pineapple, grape, etc.), alone or in mixtures. It is also possible to use compounds such as benzaldehyde, isoamyl acetate, ethyl butyrate, etc.

The antimicrobial agents can be chosen from thymol, menthol, triclosan, 4-hexylresorcinol, phenol, eucalyptol, benzoic acid, benzoic peroxide, butyl paraben, and their mixtures.

It should be noted that it is not impossible that the oily phase itself is considered as a hydrophobic active material.

In the case where the internal oily phase comprises one or more hydrophobic active materials different from the oily phase, their content represents more particularly 10 to 50% by weight of said internal oily phase.

The reverse emulsion further comprises at least one nonionic surfactant and / or at least one amphiphilic polymer, preferably with blocks.

It should be noted that the Bancroft rule can be applied to the nonionic surfactant and to the amphiphilic polymer, preferably to blocks, used (2 ^nd World Congress of Emulsion, 1997, Bordeaux, France). In other words, the fraction soluble in the continuous phase is greater than the fraction soluble in the dispersed phase. Thus, the surfactant and the polymer are preferably chosen from those which satisfy both of the two conditions below:

- when mixed with the internal oily phase, at a concentration of between 0.1 and 10% by weight of said phase at 25 ° C, are in the form of a solution in all or part of the range of indicated concentration. - when mixed with the internal aqueous phase, at a concentration between 0.1 and 10% by weight of said phase and at 25 ° C, are in the form of a dispersion in all or part of the range of indicated concentration. More particularly, the nonionic surfactant is chosen from compounds having an HLB (hydrophilic / lipophilic balance) value less than or equal to 8.

As examples of surfactants capable of entering into the composition of the reverse emulsion, mention may be made of surfactants, alone or as a mixture, chosen from:

- alkoxylated fatty alcohols

- alkoxylated triglycerides - alkoxylated fatty acids

- optionally alkoxylated sorbitan esters

- alkoxylated fatty amines

- alkoxylated di (phenyl-1 ethyl) phenols - alkoxylated tri (1-phenylethyl) phenols

- alkoxylated alkyl phenols the number of alkoxylated units (ethoxylated, propoxylated, butoxylated) is such that the value of HLB is less than or equal to 8. The alkoxylated fatty alcohols generally comprise from 6 to 22 carbon atoms, the alkoxylated units being excluded of these numbers.

The alkoxylated triglycerides can be triglycerides of plant or animal origin.

The optionally alkoxylated sorbitan esters are cyclized fatty acid sorbitol esters comprising from 10 to 20 carbon atoms such as lauric acid, stearic acid or oleic acid.

Alkoxylated fatty amines generally have from 10 to 22 carbon atoms, the alkoxylated units being excluded from these numbers.

Alkoxylated alkylphenols generally have one or two alkyl groups, linear or branched, having 4 to 12 carbon atoms. By way of example, mention may in particular be made of octyl, nonyl or dodecyl groups.

As for the amphiphilic polymer, this advantageously comprises at least two blocks.

These amphiphilic polymers, verifying the Bancroft rule and the two conditions stated above, more particularly comprise at least one hydrophobic block and at least one neutral or anionic hydrophilic block.

In the case where the amphiphilic polymer comprises at least three blocks, and more particularly three blocks, the polymer is preferably linear. In addition, the hydrophobic blocks are more particularly at the ends. If the polymers comprise more than three blocks, the latter are preferably in the form of grafted or combed polymers.

In what follows, even if this constitutes an abuse of language, the term amphiphilic block polymer will be used interchangeably for linear block polymers and grafted or combed polymers. Said amphiphilic polymers can advantageously be obtained by so-called living or controlled radical polymerization. By way of nonlimiting examples of so-called living or controlled polymerization processes, reference may in particular be made to applications WO 98/58974 (xanthate), WO 98/01478 (dithioesters), WO 99/03894 (nitroxides); WO 99/31144 (dithiocarbamates). Amphiphilic polymers can also be obtained by anionic polymerization. They can likewise be prepared by bringing into play polymerizations by ring opening (in particular anionic or cationic), or by chemical modification of the polymer.

The grafted or combed polymers can also be obtained by methods known as direct grafting and copolymerization.

Direct grafting consists in polymerizing the monomer (s) chosen by radical, in the presence of the selected polymer to form the backbone of the final product. If the monomer / skeleton couple as well as the operating conditions are judiciously chosen, then there may be a transfer reaction between the growing macroradical and the skeleton. This reaction generates a radical on the skeleton and it is from this radical that the graft grows. The primary radical originating from the initiator can also contribute to the transfer reactions.

As regards the copolymerization, it first implements the grafting at the end of the future pendant segment, of a function which can be polymerized by the radical route. This grafting can be carried out by usual methods of organic chemistry. Then, in a second step, the macromonomer thus obtained is polymerized with the monomer chosen to form the skeleton and a so-called "comb" polymer is obtained. Among the hydrophobic monomers from which the hydrophobic block (s) of the amphiphilic polymer can be prepared, there may be mentioned in particular: - the esters of mono- or polycarboxylic acids, linear, branched, cyclic or aromatic, comprising at least one ethylenic unsaturation , esters of saturated carboxylic acids preferably comprising 8 to 30 carbon atoms, optionally carrying a hydroxyl group; - αβ-ethylenically unsaturated nitriles, vinyl ethers, vinyl esters, vinyl aromatic monomers, vinyl or vinylidene halides, hydrocarbon monomers, linear or branched, aromatic or not, comprising at least one ethylenic unsaturation, monomers of cyclic or non-cyclic siloxane type, chlorosilanes; propylene oxide, butylene oxide; alone or in mixtures, as well as the macromonomers derived from such monomers.

As specific examples of hydrophobic monomers capable of entering into the preparation of the hydrophobic block (s) of the amphiphilic block polymer, mention may be made of: (meth) acrylic acid esters with an alcohol comprising 1 to 12 carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate,

propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl acrylate; vinyl acetate, vinyl Versatate®, vinyl propionate, vinyl chloride, vinylidene chloride, methyl vinyl ether, ethyl vinyl ether; vinyl nitriles more particularly include those having 3 to 12 carbon atoms, such as in particular acrylonitrile and methacrylonitrile; - styrene, α-methylstyrene, vinyltoluene, butadiene, isoprene, chloroprene; alone or in mixtures, as well as the macromonomers derived from such monomers.

The preferred monomers are the esters of acrylic acid with linear or branched C1-C4 alcohols such as methyl, ethyl, propyl and butyl acrylate, vinyl esters such as vinyl acetate, styrene, α-methylstyrene.

As regards the nonionic hydrophilic monomers from which the amphiphilic block polymers can be obtained, there may be mentioned, without intending to be limited thereto, ethylene oxide, the amides of mono- or polycarboxylic acids , linear, branched, cyclic or aromatic, comprising at least one ethylenic unsaturation or derivatives, such as (meth) acrylamide, N-methyloI (meth) acrylamide; hydrophilic esters derived from (meth) acrylic acid such as for example 2-hydroxyethyl (meth) acrylate; vinyl esters making it possible to obtain polyvinyl alcohol blocks after hydrolysis, such as vinyl acetate, vinyl Versatate®, vinyl propionate, alone, in combination, as well as the macromonomers derived from such monomers. It is recalled that the term macromonomer designates a macromolecule carrying one or more polymerizable functions.

However, the preferred hydrophilic monomers are acrylamide and methacrylamide, alone or as a mixture, or in the form of macromonomers. As regards the anionic hydrophilic monomers from which the amphiphilic block polymers can be obtained, mention may be made, for example, of the monomers comprising at least one carboxylic, sulfonic, sulfuric, phosphonic, phosphoric, sulfosuccinic function, or the corresponding salts.

It is specified that under the pH conditions of use of the amphiphilic block polymer, the functions of the anionic block or blocks of the polymer are in an at least partially ionized (dissociated) form. More particularly, at least 10 mol% of the functions of the block or blocks are in ionized form. The determination of this value poses no problem to those skilled in the art; it is in particular a function of the pKa of the ionizable functions of the units of the polymer and of the number of these functions (ie the number of moles of monomer carrying ionizable functions used during the preparation of the polymer).

More particularly, the monomers are chosen from: - linear, branched, cyclic or aromatic mono- or polycarboxylic acids, N-substituted derivatives of such acids; monoesters of polycarboxylic acids, comprising at least one ethylenic unsaturation;

- linear, branched, cyclic or aromatic vinyl carboxylic acids; - amino acids comprising one or more ethylenic unsaturations; alone or as mixtures, their precursors, their sulfonic or phosphonic counterparts, as well as the macromonomers derived from such monomers; the monomers or macromonomers which may be in the form of salts.

As examples of anionic monomers, there may be mentioned without intending to be limited thereto:

- acrylic acid, methacrylic acid, fumaric acid, itaconic acid, citraconic acid, maleic acid, acrylamido glycolic acid, 2-propene 1- sulfonic acid, acid methallyl sulfonic, styrene sulfonic acid, α-acrylamido methylpropane sulfonic acid, 2-sulfoethylene methacylate, sulfopropyl acrylic acid, bis-sulfopropyl acrylic acid, bis-sulfopropyl methacrylic acid, sulfatoethyl acid methacrylic, hydroxyethyl methacrylic acid phosphate ester, as well as alkali metal salts, such as sodium, potassium, or ammonium;

- vinyl sulfonic acid, vinylbenzene sulfonic acid, vinyl phosphonic acid, vinylidene phosphoric acid, vinyl benzoic acid, as well as alkali metal salts, such as sodium, potassium, or ammonium ;

- N-methacryloyl alanine, N-acryloyl-hydroxy-glycine; alone or in mixtures, as well as the macromonomers derived from such monomers.

It would not be departing from the scope of the present invention to use monomers which are precursors of those which have just been mentioned. In other words, these monomers have units which, once incorporated in the polymer chain, can be transformed, in particular by a chemical treatment such as hydrolysis, to restore the aforementioned anionic species. For example, the fully or partially esterified monomers of the aforementioned monomers can be used to be, subsequently, completely or partially hydrolyzed.

Preferably, the amphiphilic block polymers have a molar mass by weight less than or equal to 100,000 g / mol, more particularly between 1,000 and 50,000 g / mol, preferably between 1,000 and 20,000 g / mol. It is specified that the molar masses by weight indicated above are theoretical molar masses, evaluated as a function of the respective amounts of the monomers introduced during the preparation of said polymers.

Preferably, an amphiphilic polymer with nonionic type blocks is used. By way of example of an amphiphilic block polymer suitable for implementing the invention, mention may be made of polyhydroxystearate - polyethylene glycol - polyhydroxystearate triblock polymers (the products of the Arlacel range from ICI are an example), polymers with polydimethylsiloxane blocks grafted polyalkyl polyether (like the products of the brand Tegopren marketed by Goldschmidt).

Preferably, at least one surfactant, at least one nonionic amphiphilic polymer, or mixtures thereof, is used.

According to a particularly advantageous embodiment, the reverse emulsion comprises an amphiphilic polymer, preferably block and nonionic, or a mixture of several of them.

The total amount of surfactant and / or amphiphilic polymer preferably represents from 2 to 10% by weight of the internal oily phase.

The internal aqueous phase comprises at least one hydrophilic active material, which is in a form soluble in the internal aqueous phase; in a form dissolved in a water-miscible solvent such as methanol, ethanol, propylene glycol, glycerol; in the form of a divided solid dispersed in said phase.

The content of hydrophilic active material is more particularly between 0.1 and 50% by weight of the internal aqueous phase, and preferably between 0.1 and 20% by weight of the internal aqueous phase. As examples of active materials which can be used in the field of cosmetics, mention may be made of substances which have a cosmetic effect, a therapeutic effect or any other substance which can be used for the treatment of skin and hair.

Thus, it is possible to use, as active material, skin and hair conditioning agents, such as in particular polymers comprising quaternary ammoniums which can optionally be used in heterocycles (compounds of the quaternium, polyquaternium type, etc.). , humectants; fixing agents (styling) which are more particularly chosen from polymers (homo-, co- or ter-polymers, for example acrylamide, acrylamide / sodium acrylate, polystyrene sulfonate, etc.), cationic polymers, polyvinylpyrrolidone, polyvinyl acetate, etc.

It is likewise possible to use coloring agents; astringent agents, which can be used in deodorants and which are more particularly aluminum, zirconium salts; antibacterial agents; anti-inflammatory agents, anesthetic agents, sunscreens, etc.

Mention may also be made of - and β-hydroxy acids, such as citric, lactic, glycolic and salicylic acids; dicarboxylic acids, preferably unsaturated and comprising 9 to 16 carbon atoms such as azelaic acid; vitamin C and its derivatives, in particular glycosylated and phosphate derivatives; biocides, in particular cationic biocides, as suitable active materials in cosmetic and / or dermatological formulations.

In accordance with a particularly advantageous embodiment of the present invention, the internal aqueous phase may comprise at least one additive chosen from salts such as the halides of alkali or alkaline earth metals (such as sodium chloride, calcium chloride) , or alkali or alkaline earth metal sulfates (such as magnesium sulfate), or mixtures thereof. The internal aqueous phase can also comprise, as an additive, at least one sugar, such as glucose for example, or also at least one polysaccharide, such as in particular dextran, or mixtures thereof. We can obviously have a combination of these various types of additives.

The salt concentration in the internal aqueous phase, when the latter is present, is more particularly between 0.05 and 1 mol / l, preferably 0.1 to 0.4 mol / l.

The sugar and / or polysaccharide concentration, if it is used, is such that the osmotic pressure of the internal aqueous phase comprising the sugar and / or polysaccharide corresponds to the osmotic pressure of a internal aqueous phase comprising 0.05 to 1 mol / l of salt. In addition, the inverse emulsion of the multiple emulsion more particularly has a weight proportion aqueous phase / oily phase of between 10/90 and 90/10. Preferably, the weight proportion of aqueous phase / oily phase is between 30/70 and 80/20.

The reverse emulsion is prepared by implementing the conventional methods. Thus, to cite only one example, a first mixture is prepared, comprising water, the hydrophilic active material and optionally the additive (salt, sugar, polysaccharide), and on the other hand, a second mixture comprising the oil, optionally the hydrophobic active material and the surfactant and / or the amphiphilic polymer. The first mixture is then added to the second, with stirring. In the case where the oily phase is not very viscous (viscosity less than 1 Pa.s) the stirring is preferably strong and can be, advantageously, provided by the use of an apparatus of the Ultra-Turrax® type, Microfluidizer, or any high pressure homogenizer.

In the case where the oily phase is viscous (viscosity greater than or equal to 1 Pa.s, preferably greater than or equal to 5 Pa.s), the stirring can advantageously be carried out by means of a frame blade. The preparation of the reverse emulsion is generally carried out at a temperature above the melting temperature of the oily phase. Usually, the temperature for preparing the reverse emulsion is between 20 and 80 ° C.

The duration of the agitation can be determined without difficulty by a person skilled in the art and depends on the type of apparatus used. It is preferably sufficient to obtain an average droplet size of between 0.1 and 10 μm, preferably between 0.1 and 5 μm (measured using a Horiba granulometer)

The external aqueous phase of the multiple emulsion will now be described.

As indicated previously, the external aqueous phase can comprise at least one active material which is dissolved in the external aqueous phase, either in a form dissolved in a solvent miscible with the external aqueous phase, such as methanol, ethanol , propylene glycol, glycerol, either in the form of a divided solid dispersed in said external aqueous phase.

The content of active material, if it is present, is more particularly between 0.1 and 50% by weight of the external aqueous phase, and preferably between 0.1 and 20% by weight of the external aqueous phase.

According to a first possibility, the external aqueous phase additionally comprises at least nonionic surfactant and / or at least one nonionic amphiphilic polymer optionally associated with at least one anionic amphiphilic polymer. According to a second possibility, the external aqueous phase comprises at least one anionic amphiphilic polymer optionally combined with at least one anionic surfactant. It should be noted that the Bancroft rule can be applied to the surfactants and polymers used (fraction soluble in the continuous phase is greater than the fraction soluble in the dispersed phase). Thus, the surfactant and the polymer are preferably chosen from those which satisfy both of the two conditions below:

- when mixed with the external aqueous phase, at a concentration of between 0.1 and 10% by weight of said phase at 25 ° C, are in the form of a solution in all or part of the range of indicated concentration. - when mixed with the internal oily phase, at a concentration between 0.1 and 10% by weight of said phase and at 25 ° C, are in the form of a dispersion in all or part of the range of indicated concentration. More particularly, the external aqueous phase comprises: - at least one nonionic surfactant and / or at least one nonionic amphiphilic polymer optionally combined with at least one anionic surfactant and / or at least one anionic amphiphilic polymer; the total content of nonionic and anionic amphiphilic surfactant (s) / polymer (s) is between 0.5 and 10% by weight, preferably between 1 and 5% by weight, relative to the oily phase or to the reverse emulsion if it is present; the amount of anionic amphiphilic surfactant and / or polymer represents 0.5 to 5% by weight, preferably 0.5 to 2% by weight, relative to the weight of nonionic amphiphilic surfactant / polymer; or

- At least one anionic amphiphilic polymer optionally combined with at least one anionic surfactant; the total content of amphiphilic polymer / anionic surfactant is between 0.5 and 10% by weight, preferably between 1 and 5% by weight, relative to the oily phase or to the reverse emulsion if it is present.

Advantageously, the surfactants and polymers chosen do not give a liquid crystal phase in the aqueous phase.

As regards nonionic surfactants, polyalkoxylated nonionic surfactants are preferably used. Advantageously, said nonionic surfactant is chosen from the following surfactants, alone or as a mixture:

- alkoxylated fatty alcohols

- alkoxylated triglycerides

- alkoxylated fatty acids - alkoxylated sorbitan esters

- alkoxylated fatty amines

- alkoxylated di (phenyl-1 ethyl) phenols

- alkoxylated tri (1-phenylethyl) phenols

the alkoxylated alkylphenols the number of alkoxylated units, more particularly ethoxylated and / or propoxylated, is such that the value of HLB is greater than or equal to 10.

As regards the nonionic amphiphilic polymer, a polymer comprising at least two blocks is used, one of them being hydrophilic, the other hydrophobic. What has been indicated previously in the context of the description of the nonionic hydrophilic monomers and of the hydrophobic monomers which can be used for the preparation of amphiphilic block polymers entering into the composition of the reverse emulsion, remains valid and will not be repeated here; The proportion and the nature of said monomers being such that the resulting polymer satisfies the conditions set out previously (Bancroft rule - two conditions).

According to a particular embodiment, the polymer is obtained from hydrophilic monomers chosen from acrylamide and methacrylamide, alone or as a mixture, or in the form of macromonomers; hydrophobic monomers preferred are acrylic acid esters with linear or branched C1-C4 alcohols such as methyl, ethyl, propyl and butyl acrylate, vinyl esters such as vinyl acetate, styrene, the α-methylstyrene.

In the case where said polymer comprises at least three blocks, and more particularly three blocks, the polymer is advantageously linear. In addition, the hydrophilic blocks are more particularly at the ends.

If the polymers comprise more than three blocks, the latter are preferably in the form of grafted or combed polymers.

According to another advantageous embodiment, the amphiphilic polymer comprises polyalkoxy blocks, and preferably only comprises polyalkoxy blocks, at least one of which is hydrophobic, the other hydrophilic.

For purely indicative purposes, these polymers are obtained by bringing into play ring-opening polymerizations, in particular anionic.

More particularly, said nonionic polyalkoxy amphiphilic polymers are chosen from polymers whose molar mass by weight is less than or equal to 100,000 g / mol (measured by GPC, polyethylene glycol standard), preferably between 1,000 and 50,000 g / mol, preferably between 1000 and 20000 g / mol.

Examples of polymers of this type that may be mentioned, inter alia, are polyethylene glycol / polypropylene glycol / polyethylene glycol triblock polymers. Such polymers are well known and are in particular marketed under the brands Pluronic (marketed by BASF), Arlatone (marketed by ICI).

Among the suitable anionic surfactants, there may be mentioned, among others, alone or in mixtures:

- the alkyl esters sulfonates, for example of formula R-CH (SO ₃ M) -COOR ', where R represents an alkyl radical in C ₈ -C ₂ o, preferably in C ₁₀ -C ₁₆ , R' an alkyl radical in Ci-Ce, preferably in C Ca and M an alkali cation (sodium, potassium, lithium), substituted or unsubstituted ammonium (methyl-, dimethyl-, trimethyl-, tetramethylammonium, dimethylpiperidinium ...) or derived from an alkanolamine (monoethanolamine, diethanolamine, triethanolamine ...). Mention may very particularly be made of methyl ester sulfonates whose radical R is in

C ₁₄ -C ₁₆ ; alkylbenzenesulfonar.es, more particularly in C ₉ -C ₂ o, primary or secondary alkylsulfonates, in particular in Cβ-Ca., alkylglycerol sulfonates, sulfonated polycarboxylic acids, such as for example those described in GB 1082179, paraffin sulfonates ; the alkyl sulphates, for example of formula ROSO ₃ M, where R represents a C ₁₀ -C ₂₄ , preferably C ₁₂ -C ₂ o, alkyl or hydroxyalkyl radical; M representing a hydrogen atom or a cation of the same definition as above, thus as their polyalkoxylated derivatives (ethoxylated (OE), propoxylated (OP), or their combinations), such as for example sodium dodecylsulfate;

the alkyl ether sulphates, for example of formula RO (CH ₂ CH ₂ O) _n SO ₃ M where R represents a C ₁₀ -C ₂₄ , preferably C ₁₂ -C ₂₀ , alkyl or hydroxyalkyl radical; M representing a hydrogen atom or a cation of the same definition as above, n generally varying from 1 to 4, as well as their polyalkoxy derivatives (ethoxylates (OE), propoxyls (OP), or their combinations), such as for example laurylethersulfate with n = 2.

the sulphated alkylamides, for example of formula RCONHR'OSO ₃ M where R represents a C ₂ -C ₂₂ , preferably C ₆ -C ₂₀ , alkyl radical, R ′ a C ₂ -C ₃ alkyl radical, M representing a hydrogen atom or a cation of the same definition as above, as well as their polyalkoxy derivatives (ethoxylates (OE), propoxyls (OP), or their combinations);

the salts of saturated or unsaturated fatty acids, for example such as those in C ₈ - C ₂₄ , preferably in C ₁₄ -C ₂₀ , N-acyl N-alkyltaurates, alkylisethionates, alkylsuccinamates and alkylsulfosuccinates, monoesters or sulfosuccinate diesters, N-acyl sarcosinates, polyethoxycarboxylates; and

- the alkyl and / or alkyl ether and / or alkylaryl ether ester phosphates.

Among the anionic polymers capable of being used, mention may be made most particularly of block polymers, preferably diblocks or triblocks, obtained by polymerization of at least one anionic hydrophilic monomer, optionally of at least one nonionic hydrophilic monomer, and at least one hydrophobic monomer.

Here again, the choice of monomers and their respective proportions are such that the resulting polymer satisfies the two conditions previously stated (Bancroft rule).

Non-ionic, anionic hydrophilic monomers, hydrophobic monomers as well as the methods of synthesis mentioned in the context of the description of the amphiphilic polymers entering into the composition of emulsions for which the continuous phase is an oil phase, can be used for obtaining polymers according to this variant. We can therefore refer to it.

Note that it would not be departing from the scope of the present invention to combine one or more surfactants with one or more amphiphilic polymers.

However, according to a preferred embodiment of the invention, the external aqueous phase comprises one or more amphiphilic polymers. Furthermore, it would not be departing from the scope of the present invention to use a cationic amphiphilic polymer, in combination with the nonionic surfactant and / or the aforementioned nonionic amphiphilic polymer. Among the cationic polymers capable of being used in the context of the present invention, mention may very particularly be made of cationic derivatives of polysaccharides, such as guar or cellulose derivatives.

It is likewise possible to use cationic polymers functionalized by hydrophobic groups such as C1-C14, preferably C2-C8 alkyl chains, optionally having a hydroxyl group. These hydrophobic groups are attached to the main polymer chain via ether bonds.

Furthermore, and in the case of cationic guars modified hydrophobic or not, the cationic group is a quaternary ammonium group carrying three radicals, identical or not, chosen from hydrogen, an alkyl radical comprising 1 to

22 carbon atoms, more particularly 1 to 14, advantageously 1 to 3 carbon atoms. The counter ion is a halogen, preferably chlorine.

In the case of cationic celluloses modified hydrophobic or not, the cationic group is a quaternary ammonium group carrying three radicals, identical or not, chosen from hydrogen, an alkyl radical comprising 1 to

10 carbon atoms, more particularly 1 to 6, advantageously 1 to 3 carbon atoms. The counter ion is a halogen, preferably chlorine.

In addition, the weight ratio of inverse emulsion relative to the external aqueous phase in the multiple emulsion is usually between 30/70 and 90/10, preferably between 50/50 and 90/10.

In order to balance the osmotic pressures of the external aqueous phase and of the internal aqueous phase, it is possible to add to the external aqueous phase at least one additive chosen from salts such as the halides of alkali or alkaline earth metals (such as chloride sodium, calcium chloride), among alkali or alkaline earth metal sulfates (such as magnesium sulfate), among sugars (glucose for example), or among polysaccharides (especially dextran) or their mixtures.

The additive (salt, sugar and / or polysaccharide) concentrations are such that the osmotic pressures of the external and internal aqueous phases are balanced. In addition, depending on the application for which the emulsion according to the invention is intended, or depending on the nature of the active material, it may be advantageous to adjust the pH of the external aqueous phase by adding base. (soda, potash) or acid (hydrochloric). By way of illustration, the usual range of pH of the external aqueous phase is between 3 and 8, preferably between 5 and 8.

It should be noted that if the internal oily phase has a relatively high viscosity, for example greater than or equal to 1 Pa.s, more particularly greater or equal to 5 Pa.s, it may be advantageous to add to the external aqueous phase, at least one heat-thickening polymer.

It is recalled that this type of polymer has the particularity of giving aqueous solutions whose viscosity increases when the temperature exceeds a certain threshold temperature. More particularly, these polymers are soluble in water at ambient temperature, and beyond the threshold temperature, part of the polymer becomes hydrophobic (thermosensitive part): the polymer thus forms a physical network on a microscopic scale, this which results at the macroscopic scale by an increase in viscosity. According to an advantageous embodiment of the present invention, the heat-thickening polymer used is chosen from polymers having a viscosity jump between 25 and 80 ° C such that the value of the logio ratio (viscosity at 80 ° C) / logio ( viscosity at 25 ° C) is at least equal to at least 1. The ratio is measured under the following conditions: * The polymer is first dissolved in water (dry extract of 4%).

* The rheological profile is then measured in flow mode with imposed stress, by performing a temperature sweep between 20 ° C and 80 ° C. The configuration used is the 4cm / 1 degree cone-plane geometry. The constraint introduced in the program is chosen (in manual mode) so that the gradient at 25 ° C is 10 s ¹ .

* The quantity that was used to characterize the thermo-thickening power of the polymer, namely the ratio logio (viscosity at 80 ° C) / logio (viscosity at 25 ° C), represents the jump in viscosity, expressed in decades, from 25 to 80 ° C. This quantity expressed in other words that the viscosity of the medium at 80 ° C is 10 times ⁿ the middle of the viscosity at 25 ° C; with n integer between 0 and 5.

In addition to this characteristic, the heat-thickening polymer is chosen so that the variation in viscosity is reversible.

Among the heat-thickening polymers which can be used, mention may be made of hydrophobic modified polysaccharides such as carboxymethyl celluloses, methyl celluloses, hydroxyethyl celluloses, hydroxypropyl celluloses.

In the case of this type of polymers, it may be advantageous to use them associated with at least one additional surfactant, chosen from nonionic or even anionic surfactants.

Synthetic polymers such as polymers based on N-isopropyl acrylamide, polymers based on N, N-dimethyl aminoethyl methacrylate are also suitable.

Comb structure polymers consisting of a polymer backbone segment on which are grafted at least two polymer side segments, identical or not, for which either the polymer backbone segment or the side segments polymers have a lower critical solubility temperature, LCST, between 25 and 80 ° C. Preferably, the polymeric lateral segments are heat-sensitive and are derived from polyoxyalkylenated polymers.

As examples of polymers of this type, mention may be made in particular of polymers prepared from tri-block polymer POE-POP-POE and acrylic acid (respective molar percentages: 2.3%, 97.7% , direct grafting), polymers prepared from macromonomer of POE-POP-POE tri-blocks and acrylic acid (respective molar%: 1.6%, 98.4%, copolymerization), polymers prepared from POE-POP-POE tri-block macromonomer and acrylic acid (respective mol%: 3%, 97%, copolymerization), polymers prepared from POE-POP-POE tri-block macromonomer and acrylic acid (respective molar%: 2%, 98%, copolymerization).

These polymers were the subject of a French patent application FR 2 180 422, to which reference may be made for more information on the polymers and their obtaining.

The content of heat-thickening polymer more particularly represents, when it is present, 0.2 to 10% by weight of the external aqueous phase. Preferably, the content of this polymer represents 1 to 5% by weight of the external aqueous phase.

According to an advantageous variant of the present invention, the external aqueous phase of the multiple emulsion can comprise at least one thickening polymer. This polymer has the particular effect of avoiding creaming and / or sedimentation of the final emulsion.

By way of illustration, it is possible to use thickening polymers extracted from plants and optionally modified, such as carrageenans, alginates, carboxymethyl celluloses, methylcelluloses, hydroxypropyl celluloses, hydroxyethyl celluloses.

It is likewise possible to use thickening polymers of the type of polysaccharides of animal, vegetable or bacterial origin, there may be mentioned by way of nonlimiting example, xanthan gum, guar and derivatives (such as hydroxypropyl guar for example) , polydextroses, or combinations thereof.

When present, the thickening polymer content is more particularly between 0.1 and 2% by weight relative to the external aqueous phase, preferably between 0.1 and 0.5% by weight relative to the phase external aqueous.

Note that in this concentration range, the thickening polymer is soluble in the aqueous phase.

According to another variant of the invention, the external aqueous phase comprises a dispersed external oily phase. Optionally, said external aqueous phase may also comprise at least one dispersed divided solid. The external oily phase can also comprise at least one hydrophobic active material.

In the case where the external oily phase comprises one or more hydrophobic active materials different from the oily phase, their content represents more particularly less than or equal to 50% by weight of said external oily phase, preferably from 0.5 to 50% by weight , advantageously between 0.5 and 20% by weight.

More particularly, if the external aqueous phase does not comprise a soluble active material, solubilized or dispersed in the form of a divided solid, the external oily phase then comprises at least one hydrophobic active material. Note that it is not excluded that both the external aqueous and oily phases each comprise at least one active ingredient.

All that has been indicated previously concerning the hydrophobic active material possibly present in the internal oily phase, remains valid and will not be detailed again now. Similarly, it is recalled that said external oily phase can in itself constitute an active material.

It should be noted that these active materials can be used in the presence of conventional additives in the field of application concerned.

More particularly, and still according to this variant, the external oily phase represents from 1 to 50% by weight of the external aqueous phase, preferably 5 to 25% by weight of the external aqueous phase.

In addition, it is preferable that the size of the droplets of the external oily phase is at most of the same order of magnitude as that of the reverse emulsion dispersed in the external aqueous phase.

As for the possibility of using a solid dispersed in the external aqueous phase, all the solids used in the various types of cosmetic and / or dermatological formulations may be suitable. Preferably, the size of this or these dispersed solids is close to or smaller than that of the droplets of the reverse emulsion.

If the dispersed solid is present, its content is more ^{'particularly} 1 to 50% by weight of the external aqueous phase, preferably 5 to 25% by weight.

The preparation of the multiple emulsion can be carried out according to any known method.

As an example, we can proceed as follows. Firstly, the external aqueous phase is prepared by mixing the surfactant and / or the amphiphilic polymer, optionally the active material if the latter is present in a form soluble in the aqueous phase or dissolved in a solvent miscible with this phase, optionally the heat-thickening polymer, and water. Preferably, the water and the surfactant and / or the amphiphilic polymer are firstly mixed, with stirring, then optionally the active material and the heat-thickening polymer, and optionally the additive (salt / sugar / polysaccharide).

This operation usually takes place between 20 and 80 ° C. The external aqueous phase can optionally be left to stand for 1 to

12 hours at room temperature.

Next, the actual multiple emulsion is prepared by adding the reverse emulsion to the external aqueous phase. It should be noted that advantageously, part of the external aqueous phase is discarded, in order to be used for the preparation of the simple emulsion comprising the external oily phase dispersed in the external aqueous phase, in the event that such an emulsion is present.

The preparation of the multiple emulsion preferably takes place with stirring, adding the reverse emulsion slowly at the start.

Agitation can be done by means of a paddle frame. Typically, the stirring speed is relatively slow, of the order of 400 rpm.

According to the variant where the multiple emulsion is mixed with a simple oil-in-water emulsion, said emulsion composed of the external oily phase is advantageously dispersed in the same external aqueous phase as that used for the multiple emulsion. It should however be noted that it is not excluded to use different external aqueous phases, insofar as there is no destabilization of the mixed emulsion. Obviously, the quantities of external aqueous phase introduced with the inverse and simple emulsions are such that the weight proportions of each of the phases satisfy the conditions explained above for the mixed emulsion. Obtaining the direct emulsion is carried out according to any known method, by mixing with stirring of the two phases: the external oily phase, where appropriate the hydrophobic active material and the external aqueous phase comprising the surfactant and / or the amphiphilic polymer, optionally the soluble or solubilized active material and optionally the heat-thickening polymer. In the case where the external aqueous phase comprises a dispersed solid, the obtaining of the multiple emulsion can be carried out as indicated in the first case, then said solid dispersed in the external aqueous phase is added.

The average size of the droplets of the multiple emulsion advantageously varies between 5 and 15 μm (Horiba). Finally, if the multiple emulsion comprises a thickening agent, the latter is very advantageously incorporated once the mixed emulsion has been obtained, that is to say once all the other ingredients have been added. The mixed emulsion which has just been detailed can be used as a constituent element of cosmetic and / or dermatological formulations.

The content of mixed emulsion is preferably such that the total content of active material (s) present in the aqueous and oily phases, in the cosmetic and / or dermatological formulation is between 0.01 and 10% by weight of said formulation.

The cosmetic and / or dermatological formulations which are the subject of the invention can be formulated in a large number of types of products for the skin, the hair, the eyelashes and / or the nails, the conditioners, the formulations for styling or to facilitate combing of the hair, hand and body lotions, products regulating the hydration of the skin, toilet milks, makeup-removing compositions, depilatory products, sun protection creams or lotions and ultraviolet radiation, skincare creams, anti-acne preparations, make-up formulations such as mascaras, foundations, nail polish, products intended to be applied to the lips, etc.

Cosmetic and / or dermatological formulations, in addition to mixed emulsions, include conventional additives in the field.

It is thus possible to incorporate into the cosmetic and / or dermatological formulation, in the form of dispersions or solutions, bactericidal or fungicidal agents in order to improve the disinfection of the skin, such as for example triclosan; anti-dandruff agents, such as in particular zinc pyrithione or octopyrox; insecticidal agents such as natural or synthetic pyrethroids.

Cosmetic and / or dermatological formulations can also contain agents for protecting the skin and / or hair against the aggressions of the sun and UV rays. Thus, the compositions may include sunscreens which are chemical compounds which strongly absorb UV radiation, such as the compounds authorized in European directive N ° 76/768 / EEC, its annexes and subsequent modifications to this directive, in particular mineral particles. such as zinc oxide, titanium dioxide or cerium oxides in the form of powder or colloidal particles, alone or as a mixture. These powders can optionally be surface-treated to increase the effectiveness of their anti-UV action or to facilitate their incorporation into cosmetic formulations or to inhibit surface photoreactivity.

Said formulations may also contain fixative resins. These fixative resins, when they are present, are generally present at concentrations of between 0.01 and 10%, preferably between 0.5 and 5%.

The fixing resins used in the cosmetic compositions are more particularly chosen from the following resins: • methyl acrylate / acrylamide copolymers, polyvinylmethylether / maleic anhydride copolymers, vinyl acetate / crotonic acid copolymers, octylacrylamide / methyl acrylate / butylaminoethylmethacrylate, polyvinylpyrrolidones, polyvinylpyrrolidone copolymers, polyvinyl acrylate, , polyvinyl alcohol / crotonic acid copolymers, polyvinyl alcohol / maleic anhydride copolymers, hydroxypropyl celluloses, hydroxypropyl guars, sodium polystyrene sulfonates, polyvinylpyrrolidone / ethyl methacrylate / methacrylic acid, monomethyl ethers of poly (methylvinyl ether / polyvinyl acid) polyoxyethylene trunks (EP-A-219 048),

• copolyesters derived from acid, anhydride or a terephthalic and / or isophthalic and / or sulfoisophthalic diester and a diol, such as:

- polyester copolymers based on ethylene terephthalate and / or propylene terephthalate and polyoxyethylene terephthalate units, (US-A-3,959,230, US-A-3,893,929, US-A-4,116,896, US-A-4,702,857 , US-A-4,770,666);

- the sulfonated polyester oligomers obtained by sulfonation of an oligomer derived from ethoxylated allyl alcohol, dimethyl terephthalate and 1,2 propylene diol (US-A-4,968,451);

- polyester copolymers derived from dimethyl terephthalate, isophthalic acid, dimethyl sulfoisophthalate and ethylene glycol (EP-A-540374) copolymers comprising polyester units derived from dimethyl terephthalate, isophthalic acid, dimethyl sulfoisophthalate and d ethylene glycol and polyorganosiloxane units (FR-A-2,728,915).

- the sulfonated polyester oligomers obtained by condensation of isophthalic acid, of dimethyl sulfosuccinate and of diethylene glycol (FR-A-2 236 926)

- polyester copolymers based on propylene terephthalate and polyoxyethylene terephthalate units and terminated by ethyl, methyl units (US-A-4,711,730) or polyester oligomers terminated by alkylpolyethoxy groups (US-A-4,702,857) or anionic sulfopolyethoxy groups (US-A-4,721,580), sulfoaroyl groups (US-A-4,877,896);

- the polyesters - polyurethanes obtained by reaction of a polyester obtained from adipic acid and / or terephthalic acid and / or sulfoisophthalic acid and a diol, on a prepolymer with terminal isocyanate groups obtained from 'a polyoxyethylene glycol and a diisocyanate (FR-A-2 334 698); • ethoxylated monoamines or polyamines, polymers of ethoxylated amines (US-A-4,597,898, EP-A-11,984).

Preferably, the fixing resins are chosen from polyvinylpyrrolidone (PVP), copolymers of polyvinylpyrrolidone and of methyl methacrylate, copolymer of polyvinylpyrrolidone and vinyl acetate (VA), polyterephthalene ethylene glycol / polyethylene glycol copolymers, polyethylene glycol terephthalate / polyethylene glycol / polyisophthalate sulfonate copolymers, and mixtures thereof. These fixative resins are preferably dispersed or dissolved in the chosen vehicle.

Cosmetic and / or dermatological formulations can also contain polymeric derivatives exercising a protective function.

These polymer derivatives can be present in amounts of the order of 0.01-10% by weight of the cosmetic and / or dermatological formulation, preferably about 0.1-5% by weight, and very particularly of the order of 0.2-3% by weight.

These agents can in particular be chosen from:. non-ionic cellulose derivatives such as cellulose hydroxyethers, methylcellulose, ethylcellulose, hydroxypropyl methylcellulose, hydroxybutyl methylcellulose;

. polyvinyl esters grafted on polyalkylenated trunks such as polyvinylacetates grafted on polyoxyethylene trunks (EP-A-219048); . polyvinyl alcohols.

Cosmetic and / or dermatological formulations can also include plasticizing agents.

Said agents, if present, can represent between 0.1 to 20% by weight of the formulation, preferably from 1 to 15% by weight.

Among the particularly useful plasticizers, there may be mentioned adipates, phthalates, isophthalates, azelates, stearates, silicone copolyols, glycols, castor oil, or mixtures thereof.

It is also possible to incorporate into said cosmetic and / or dermatological formulations humectants, which include, among others, glycerol, sorbitol, urea, collagen, gelatin, aloe vera, hyaluronic acid or solvents water-soluble volatiles such as ethanol or propylene glycol, the contents of which can reach up to 60% by weight of the composition.

To further reduce irritation or aggression on the scalp, it is also possible to add water-soluble or water-dispersible polymers such as collagen or certain non-allergenic derivatives of animal or vegetable proteins (wheat protein hydrolysates for example), natural hydrocolloids ( guar, carob, tara gum, etc.) or derived from fermentation processes, and derivatives of these polycarbohydrates such as non-ionic modified celluloses such as hydroxyethylcellulose, or anionics such as carboxymethylcellulose; guar or carob derivatives such as their nonionic derivatives (for example hydroxypropylguar) or anionic derivatives (carboxymethylguar and carboxymethylhydroxypropylguar).

To these compounds, it is possible to add in combination, powders or mineral particles such as calcium carbonate, sodium bicarbonate, calcium dihydrogen phosphate, mineral oxides in powder form or in colloidal form (particles of smaller size or on the order of a micrometer, sometimes a few tens of nanometers) such as titanium dioxide, silica, aluminum salts generally used as antiperspirants, kaolin, talc, clays and their derivatives, etc. Preservatives such as methyl, ethyl, propyl and butyl esters of p-hydroxybenzoic acid, sodium benzoate, GERMABEN ^® or any chemical agent preventing the proliferation of bacteria or molds and traditionally used in cosmetic formulations and / or dermatological, can also be introduced into the present formulations, generally up to 0.01 to 3% by weight of the formulation.

The amount of these products is usually adjusted to avoid any proliferation of bacteria, molds or yeasts in cosmetic compositions.

To these ingredients can be added, if necessary, and in order to increase comfort during the use of the formulation by the consumer, one or more perfumes, coloring agents among which mention may be made of the products described in Annex IV ("List of coloring agents allowed for use in cosmetic products") of European Directive No. 76/768 / EEC of July 27, 1976, called the Cosmetic Directive, and / or opacifying agents such as pigments.

Although not compulsory, the formulation may also contain viscous or gelling polymers so as to adjust the texture of the formulation, such as crosslinked polyacrylates (Carbopol sold by Goodrich), non-cationic cellulose derivatives such as hydroxypropylcellulose. , carboxymethylcellulose, guars and their nonionic derivatives, xanthan gum and its derivatives, used alone or in combination, or the same compounds, generally in the form of water-soluble polymers modified by hydrophobic groups covalently linked to the polymer backbone such as described in patent WO 92/16187.

Cosmetic and / or dermatological formulations can also contain polymeric dispersing agents in an amount of the order of 0.1-7% by weight, to control the hardness of calcium and magnesium, agents such as:

. the water-soluble salts of polycarboxylic acids with a molecular weight by weight of the order of 2000 to 100,000 g / mol, obtained by polymerization or copolymerization of ethylenically unsaturated carboxylic acids such as acrylic acid, acid or maleic anhydride, fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, methylenemalonic acid, and very particularly polyacrylates of molecular weight by weight of the order of 2,000 to 10,000 g / mol (US-A-3,308,067), copolymers of acrylic acid and maleic anhydride with a molecular weight of about 5,000 to 75,000 g / mol (EP-A- 66915);

. polyethylene glycols of molecular weight by weight of the order of 1000 to 50,000 g / mol.

One can also advantageously add to these formulations metal sequestering agents, more particularly those sequestering calcium such as citrate ions.

A concrete but nonlimiting example of the invention will now be presented.

EXAMPLE

1 / Reverse emulsion

Composition of the reverse emulsion:

* 30% aqueous phase:

- 14% lactic acid (% by weight of 0.1 M solution expressed relative to the weight of aqueous phase)

- 86% NaCl (% by weight of 0.1 M solution expressed relative to the weight of aqueous phase)

* 70% oil phase (soybean oil and surfactant) comprising 5% surfactant (Arlacel P135; ICI - Uniquema (*);% expressed by weight relative to the weight of aqueous phase).

(*) Arlacel P 135: Polyhydroxystearate - PEG - Polyhydroxystearate; HLB = 5-6; Mw≈ 5000 g / mol)

Preparation of the reverse emulsion:

100 g of reverse emulsion are prepared, comprising 70 g of internal oily phase and 30 g of internal aqueous phase.

On the one hand, 4.2 g of 0.1 M lactic acid solution are mixed with 25.8 g of 0.1 M NaCl solution. On the other hand, 1.5 g of Arlacel P135 with 68.5 g of soybean oil.

Before mixing, the soybean oil and Arlacel were placed in an oven at 75 ° C.

The internal aqueous phase is then added to the internal oily phase, with stirring with Ultraturrax at 9500 rpm. The mixing is carried out at 75 ° C. 2 / Multiple emulsion

Composition of the multiple emulsion: * 50% reverse emulsion

* 50% dry extract in external aqueous phase containing:

- 2% of Arlatone F127G (*) (HERE - Uniquema;% by weight expressed relative to the weight of the inverse emulsion);

- 3.6% glucose (% by weight expressed relative to the weight of external aqueous phase);

- 1% of Rhodopol 23 (**) (Rhodia Chimie;% by weight expressed relative to the weight of external aqueous phase).

(*) Arlatone F127G: HO (CH2CH ₂ O) χ (OCH (CH3) CH2θ) _y (CH2CH ₂ O) _z H with verification of the following inequality: 82 <x + z <90 and the polymer comprises 7 OP units for 1 mole of product). (**) Rhodopol 23: xanthan gum.

Preparation of the multiple emulsion: Preparation of the external aqueous phase:

40 g of external aqueous phase are prepared by weighing 20 g of 2% Rhodopol 23 solution and 20 g of 4% Arlatone F F127G solution and 7.2% glucose are added.

The whole is mixed with the pale frame at 200 rpm for 5 minutes.

Preparation of the multiple emulsion:

The 50 g of the reverse emulsion obtained in point 1 / are introduced, with stirring with a frame paddle at 400 rpm, drop by drop into the external aqueous phase, at ambient temperature. Stirring is continued for another 10 minutes.

0.5 g of formaldehyde is then added and then homogenized for 5 minutes at 400 revolutions / minute.

3 / Direct retinol emulsion

Composition of the direct emulsion:

* 32.5% of oily phase comprising 4.8% by weight of retinol (*) (BASF;% by weight expressed relative to the weight aqueous phase); * 67.5% of external aqueous phase containing:

- 2% of Arlatone F127G (% by weight expressed relative to the weight of the aqueous phase);

- 5.3% glucose (% by weight expressed relative to the weight of aqueous phase);

- 1.48% of Rhodopol 23 (% by weight expressed relative to the weight of aqueous phase);

- 10% of Alkamuls T85 (**) (Rhodia Chimie;% by weight expressed relative to the weight of oily phase).

(*) retinol: 10% solution in miglyol. (**) Alkamuls T85: sorbitan ester comprising 20 ethoxylated units.

Preparation of the direct emulsion:

30 g of direct emulsion comprising 9.75 g of retinol solution and 20.25 g of aqueous phase comprising 1 g of Alkamuls T85, 12 g of 2.5% Rhodopol solution, 3.75 g of solution are prepared Arlatone 15.6%, 3.5 g of a 30% glucose solution.

The emulsion is obtained in the following manner:

9.75 g of retinol solution are mixed with 1 g of Alkamuls T85 with stirring with a paddle blade at 500 revolutions / minute. Introduced drop by drop, with stirring with a paddle frame at 500 revolutions / minute,

3.75 g of Arlatone F127G solution. At the end of the addition, stirring is continued for 10 minutes.

Agitation is then carried out with Ultra-turrax at 9500 rpm (5 minutes) and then at 20500 rpm (2 minutes). During this stirring, the emulsion is cooled. The glucose solution is then introduced into the retinol emulsion with stirring with a frame paddle at 500 rpm, then the Rhodopol 23 solution in one go, mixing with a spatula.

Finally, homogenization is carried out with Ultra-turrax at 9500 rpm.

4 / mixed emulsion

10 g of retinol emulsion are introduced all at once in 90 g of multiple emulsion.

Gently mix with a spatula and then homogenize with the paddle frame at 200 rpm for 3 minutes.

A stable mixed emulsion is obtained comprising 0.5% by weight of retinol relative to the total water.

Claims

Cosmetic and / or dermatological formulation comprising at least two active materials in a multiple emulsion consisting of an internal aqueous phase dispersed in an internal oily phase, the whole being dispersed in an external aqueous phase; the multiple emulsion being optionally mixed with a simple emulsion consisting of an external oily phase dispersed in an external aqueous phase: π the internal oily phase comprising at least one nonionic surfactant and / or at least one amphiphilic polymer and optionally at least one hydrophobic active ingredient; π the external aqueous phase comprising at least one nonionic surfactant and / or at least one nonionic amphiphilic polymer optionally associated with at least one anionic amphiphilic polymer or comprising at least one anionic amphiphilic polymer possibly associated with at least one anionic surfactant;

° at least one hydrophilic active material present in the internal aqueous phase; and π at least one active material being in soluble, solubilized form or in the form of a solid dispersed in the external aqueous phase, or being in the external oily phase.

Formulation according to Claim 1, characterized in that the surfactant and / or the polymer present in the internal oily phase are chosen from those which satisfy both of the two conditions below:

- when mixed with the internal oily phase, at a concentration of between 0.1 and 10% by weight of said phase at 25 ° C, are in the form of a solution in all or part of the range of indicated concentration. - when mixed with the internal aqueous phase, at a concentration between 0.1 and 10% by weight of said phase and at 25 ° C, are in the form of a dispersion in all or part of the range of indicated concentration.

Formulation according to one of the preceding claims, characterized in that the quantity of nonionic surfactant and / or nonionic amphiphilic polymer represents 2 to 10% by weight of the internal aqueous phase.

4. Formulation according to one of the preceding claims, characterized in that the content of hydrophilic active material present in the internal aqueous phase is between 0.1 and 50% by weight of the internal aqueous phase, and preferably between 0 , 1 and 20% by weight of the internal aqueous phase.

5. Formulation according to one of the preceding claims, characterized in that the inverse emulsion has a weight proportion aqueous phase / oily phase between 10/90 and 90/10, preferably between 30/70 and 80/20.

6. Formulation according to one of the preceding claims, characterized in that the internal aqueous phase comprises at least one additive chosen from salts such as the halides of alkali or alkaline earth metals, or the sulfates of alkali or alkaline earth metals , among sugars, or polysaccharides, or mixtures thereof.

7. Formulation according to the preceding claim, characterized in that the salt concentration in the internal aqueous phase is between 0.05 and 1 mol / l, preferably 0.1 to 0.4 mol / l and / or the concentration in sugar and / or polysaccharide is such that the osmotic pressure of the internal aqueous phase comprising the sugar and / or the polysaccharide corresponds to the osmotic pressure of an internal aqueous phase comprising 0.05 to 1 mol / l of salt.

8. Formulation according to one of the preceding claims, characterized in that the surfactant and / or the polymer present in the external aqueous phase are chosen from those which satisfy both of the two conditions below:

- when mixed with the external aqueous phase, at a concentration of between 0.1 and 10% by weight of said phase at 25 ° C, are in the form of a solution in all or part of the range of indicated concentration. - when mixed with the internal oily phase, at a concentration between 0.1 and 10% by weight of said phase and at 25 ° C, are in the form of a dispersion in all or part of the range of indicated concentration.

9. Formulation according to one of the preceding claims, characterized in that the external aqueous phase comprises at least one heat-thickening polymer.

10. Formulation according to one of the preceding claims, characterized in that the heat-thickening polymer is chosen from polymers having a viscosity jump between 25 and 80 ° C such that the value of the logio ratio (viscosity at 80 ° C) / logio (viscosity at 25 ° C) is at least equal to at least 1.

11. Formulation according to one of claims 9 or 10, characterized in that the content of heat-thickening polymer is between 0.2 and 10% by weight of the external aqueous phase, preferably between 1 and 5% by weight of the external aqueous phase.

12. Formulation according to one of the preceding claims, characterized in that the external aqueous phase comprises at least one thickening polymer.

13. Formulation according to the preceding claim, characterized in that the content of thickening polymer is between 0.1 and 2% by weight relative to the external aqueous phase, preferably between 0.1 and 0.5% by weight. compared to the external aqueous phase.

14. Formulation according to one of the preceding claims, characterized in that the weight ratio of inverse emulsion relative to the external aqueous phase in the multiple emulsion is between 30/70 and 90/10, preferably between 50 / 50 and 90/10.

15. Formulation according to one of the preceding claims, characterized in that the osmotic pressures of the external aqueous phase and of the internal aqueous phase are balanced by adding to the external aqueous phase, at least one additive chosen from salts such as the alkali or alkaline earth metal halides, the alkali or alkaline earth metal sulfates, or chosen from sugars or also from polysaccharides, or mixtures thereof.

16. Formulation according to the preceding claim, characterized in that the dispersed external oily phase represents 1 to 50% by weight of the external aqueous phase, preferably 5 to 25% by weight of the external aqueous phase.

17. Formulation according to one of the preceding claims, characterized in that the external aqueous phase comprises at least one dispersed solid. Formulation according to the preceding claim, characterized in that the dispersed solid represents 1 to 50% by weight of the external aqueous phase, preferably 5 to 25% by weight of the external aqueous phase.