WO2021255194A1 - Composition comprising a short-chain fatty acid salt and at least one long-chain fatty acid - Google Patents

Abstract

The present invention relates to a composition, notably a cosmetic composition, in particular for caring for keratin materials, in particular the skin, comprising between 0.5% and 4% by weight of short-chain fatty acid salt, at least one long-chain fatty acid, at least one polymer chosen from polyacrylamides and 2-acrylamido-2-methylpropanesulfonic acid polymers and copolymers, and at least one carboxyvinyl polymer. It also relates to a cosmetic process for caring for keratin materials, in particular the skin, comprising at least one step of applying a composition of the invention to said keratin materials.

Description

Description

Title: Composition comprising a short-chain fatty acid salt and at least one long-chain fatty acid

The present invention relates to the cosmetic field, and notably the cosmetic uses for the prevention and/or care of keratin materials, and in particular dry skin and/or aged skin, such as hyposeborrhoeic, dry skin and/or aged skin.

Technical field

Starting from 60 or 65 years old, the skin is less supple due, inter alia, to the decrease in sebum secretion.

It is known practice to introduce active agents into cosmetic and/or dermatological compositions in order to combat the signs of ageing.

The skin is a complex matrix of tissues and ensures the mediation of numerous functions for the human body. For that, the skin has specialized cells and mechanisms, many of which are unique to this organ.

Human skin is composed of two compartments, namely an upper compartment, the epidermis, and a deep compartment, the dermis. Natural human epidermis is composed mainly of four types of cells, namely keratinocytes (which constitute the vast majority), melanocytes, sebocytes and Langerhans cells.

Each of these cell types contributes, by virtue of its intrinsic functions, towards the essential role played in the body by the skin. In particular, the sebocytes present in the sebaceous glands of the skin are cells which synthesize an oily substance called sebum.

Sebum is a product excreted by the sebaceous glands of the skin in most mammals. The excretion mechanism is a holocrine mechanism by which sebum is deposited at the skin surface. One of the roles of sebum is to provide the skin with a hydrophobic coating through the sebaceous ducts. Furthermore, human sebum has unique characteristics compared to the other mammals. In particular, it contains a very small amount of cholesterol derivatives and a large amount of squalene. In particular, sebum is a mixture of triglycerides, wax esters, squalene, esters of cholesterol, cholesterol and free fatty acid.

The importance of sebum in the homeostasis of skin tissue is known: the parts of the human body that are deficient in sebum (soles of the feet and palms of the hands) reveal a morphology and aesthetics of the skin surface that are extremely different from those of the rest of the skin. Likewise, in the skin care field, it appears that certain aesthetic disorders (dry skin) and also significant dermatological disorders (premature ageing) are attributed to an absence or insufficiency of sebum at the skin surface. An example of hyposeborrhoeic dry skin, or of skin which becomes so, is observed during skin ageing. Thus, the manifestation of xerosis linked to a sebum deficiency is very frequently observed in elderly individuals, and in particular even individuals over 50 (Yamamoto, A., Serizawa, S., Ito, M. & Sato, Y. Effect of ageing on sebaceous gland activity and on the fatty acid composition of wax esters, J. Invest, Dermatol, 89, 507-512 (1987)).

Prior art

In order to overcome this problem and to afford comfortable care that has a sebum- production-stimulating effect, various solutions are currently proposed on the cosmetics market.

Moreover, in the patent application filed on 21 December 2018 in Singapore, under number 10201811547R, it is proposed to use short-chain fatty acids (SCFAs) comprising from 3 to 8 carbon atoms, in particular propionte, butyrate and valerate, in combination with long- chain fatty acids (LCFAs) with a view to increasing the synthesis of sebum lipids and also the secretion of sebum, and consequently to preventing and/or treating dry skin and/or aged skin, in particular associated with a lack of sebum secretion.

Thus, it is already known from US20090022819 that the lysate of a filamentous bacterium, Vitreoscilla filiformis , can be used for the prevention and/or treatment of dry skin.

In addition, the use of a bifidobacterium lysate for the prevention and/or treatment of dry skin is described in US20090060962.

However, in these applications, the active agent is constituted of the biomass of bacteria. One of the drawbacks of the use of this biomass is that the incorporation thereof into cosmetic compositions is capable of causing stabilization problems, and in particular a phase separation induced by sedimentation of the biomass.

None of the short-chain fatty acids (SCFAs) is known in the prior art as an active ingredient that is of use for the prevention and/or treatment of dry skin and/or aged skin. In particular, propionic acid is known from the CTFA (Personal Care Products Council) and from Shu, M. et al. [Fermentation of Propionibacterium acnes, a commensal bacterium in the human skin microbiome, as skin probiotics against methicillin-resistant Staphylococcus aureus. PloS One 8, e55380 (2013)] as an antimicrobial active agent and the salts thereof (propionate) as a pH corrector have never been described as acting on lipid production and sebum secretion.

Furthermore, among the short-chain fatty acids (SCFAs) known in cosmetics, acetate (a short-chain fatty acid comprising 2 carbon atoms) has been described as a lipid production inducer (Acne and Its Therapy, Guy F. Webster, Anthony V. Rawlings, p262). However, acetate only contributes to lipid production and not to sebum secretion. These two functions, namely lipid production and sebum secretion, are required for efficacious treatment of hyposeborrhoeic skin.

Nevertheless, the salified forms of these short-chain fatty acids, such as sodium propionate, which are water-soluble, make their galenical formulation tricky. In particular, as regards sodium propionate, since its pKa is 4.8, its salified form in cosmetic compositions for which the pH is conventionally between 6 and 7, makes its galenical formulation tricky, in particular with regard to compatibility with gelling agents conventionally used in the cosmetics industry.

In addition, it is important to maintain the pH between 6 and 7 in order to limit the risk of the formation of acid odour due to propionic acid which is given off all the more when the pH is below 5.5.

Furthermore, the presence also of a long-chain fatty acid, such as palmitic acid, implying the presence of solvents such as oils, and which can recrystallized and cause instabilities, also makes their galenical formulation tricky.

Emultions are known for formulating hydrophilic compounds and lipophilic compounds. Thus, the formulation of salified forms of short-chain fatty acids, such as sodium propionate, and of a long-chain fatty acid, such as palmitic acid, presents difficulties.

Disclosure of the invention

There therefore remains a need to have cosmetic solutions capable of stimulating sebum production by aged skin, in particular skin more than 60 years old, or even more than 65 years old, and more particularly cosmetic compositions comprising at least short-chain fatty acid salt, in particular sodium propionate, and at least one long-chain fatty acid, in particular palmitic acid, in a galenical form suitable for its application to the skin, in complete accordance with a pH conventionally used in the cosmetics industry, namely around 6 to 7. The present invention is specifically directed towards meeting this need.

Summary of the invention

Thus, according to one of its aspects, the present invention relates to a composition, notably a cosmetic composition, in particular for caring for keratin materials, in particular the skin, comprising: i)- between 0.5% and 4% by weight of short-chain fatty acid salt, comprising a linear or branched, saturated or unsaturated aliphatic chain containing 3 to 8 carbon atoms, preferably 3 to 5 carbon atoms, relative to the total weight of the composition, and ii)- at least one long-chain fatty acid salt, comprising a linear or branched, saturated or unsaturated aliphatic chain containing 10 to 24 carbon atoms, preferably 16 to 18 carbon atoms; iii)- at least one polymer chosen from polyacrylamides and 2-acrylamido-2- methylpropanesulfonic acid polymers and copolymers; and iv)- at least one carboxyvinyl polymer.

The inventors have noted, surprisingly, that in short-chain fatty acid salt, in particular sodium propionate, and a long-chain fatty acid, in particular palmitic acid, can advantageously be formulated in a composition, in the form of an emulsion, notably in the form of an oil-in water emulsion, comprising at least one polymer chosen from polyacrylamides and 2- acrylamido-2-methylpropanesulfonic acid polymers and copolymers, and at least one carboxyvinyl polymer, which is preferably unmodified.

The inventors have notably observed that, although acrylic polymers hydrophobically modified with C16-C30 alkyl chains are known to confer advantageous compatibility with salts, this property was not verified in the presence of a short-chain fatty acid salt, in particular in the presence of sodium propionate, and of a long-chain fatty acid, in particular palmitic acid, as reported in the experimental section below.

The inventors have noted, surprisingly, that the compositions according to the invention make it possible to effectively stabilize a short-chain fatty acid salt, in particular sodium propionate, in amounts that can range from 0.5% 4% by weight, relative to the total weight of the composition, in particular that can range from 1% to 3% by weight, in the presence of a long-chain fatty acid, in particular palmitic acid, optionally in combination with other additional active agents.

Indeed, as emerges from the examples featured below, the compositions according to the invention are stable, notably from a rheological viewpoint.

A composition according to the invention is in particular used for skin care.

Thus, according to another of its aspects, the invention further relates to a cosmetic process for caring for keratin materials, in particular the skin, comprising at least one step of applying a composition according to the invention to the skin.

The invention also relates to a cosmetic treatment process for preventing and/or treating dry and/or aged skin, in particular hyposeborrhoeic dry and/or aged skin, comprising at least one step of applying a composition according to the invention to the skin.

Other features, variants and advantages of the compositions according to the invention will emerge more clearly on reading the description and the examples that follow.

The term "keratin materials" notably means the skin, the lips, in particular the skin and/or the lips, and preferably the skin.

In the context of the invention, the term “skin” denotes any skin surface of the body, preferentially facial skin and the scalp. It is envisaged that the skin involved in the present application is human skin.

As used herein, the term “treating” or “treatment” refers to any action aimed at improving the comfort or the well-being of an individual. This term therefore covers the reduction, relief or elimination of the symptoms of dry skin and/or of aged skin, but is not limited to a cosmetic treatment.

For the purposes of the present invention, the term “preventing” means reducing the risk of manifestation of a phenomenon, notably, in the context of the invention, dry skin and/or aged skin.

The term “hyposeborrhoeic” means a lack of sebum secretion, notably an absence of or a decrease in sebum secretion of the sebaceous glands. Conventionally, a sebum content of less than 100 pg/cm², measured in the T zone of the face, by the method described in FR 2 368 708, can be considered as a characteristic of hyposeborrhoeic, dry skin and of aged skin. For the purposes of the present invention, the term “cosmetic composition” denotes a composition suitable for application to the skin, in particular a composition which comprises a physiologically acceptable medium.

The term “physiologically acceptable medium” means a medium which is suitable for the topical administration of a composition, that is to say which is compatible (non-toxic) with the skin of the face, of the body and of the scalp.

For the purposes of the present invention, the term “short-chain fatty acid” means a carboxylic acid with an aliphatic chain comprising 3 to 8 carbon atoms, preferably a carboxylic acid with an aliphatic chain comprising 3 to 5 carbon atoms.

For the purposes of the present invention, the term “long-chain fatty acid” means a carboxylic acid with an aliphatic chain comprising 10 to 24 carbon atoms, preferably a carboxylic acid with an aliphatic chain comprising 16 to 18 carbon atoms.

Detailed description

SALTS OF SHORT-CHAIN FATTY ACID COMPRISING FROM 3 TO 8 CARBON ATOMS

More particularly, the short-chain fatty acids according to the invention comprise a linear or branched, saturated or unsaturated aliphatic chain containing 3 to 8 carbon atoms, preferably 3 to 5 carbon atoms.

According to one embodiment of the invention, the short-chain fatty acid comprises a linear and saturated aliphatic chain comprising from 3 to 5 carbon atoms.

According to an even more particular embodiment, the short-chain fatty acid is chosen from propionic acid, butyric acid and valeric acid, and mixtures thereof.

Advantageously, the short-chain fatty acids according to the invention do not contain a hydroxylated aliphatic chain; preferably, the short-chain fatty acids are not alpha-hydroxy acids and beta-hydroxy acids, notably are not lactic acid.

The short-chain fatty acid salts according to the invention may be any salt suitable for cosmetic use. Mention may particularly be made of calcium salts, sodium salts, magnesium salts and potassium salts, the most particularly preferred being sodium salts.

Amino acid salts may also be used. For example, a carnitine salt or lysine salt of short-chain fatty acids according to the invention may be used. Those skilled in the art are capable of identifying various other amino acids that can also be used in the context of the present invention. Thus, according to one particular embodiment of the invention, the short-chain fatty acid salt is chosen from a salt of propionic acid salt, of butyric acid or of valeric acid, or of a mixture thereof, it being possible for the salt to be chosen from calcium salts, sodium salts, magnesium salts and potassium salts and more particularly sodium salts, particularly sodium propionate.

By way of examples of short-chain fatty acid salts suitable for the invention, mention may be made of the sodium butyrate (Ref. 303410) sold by Sigma, the sodium propionate (Ref. PI 880) sold by Sigma or the sodium propionate available under the trade name Sodium Propionate from Dr. Paul Lohmann.

According to one particular embodiment, the short-chain fatty acid is obtained from at least one microorganism of the species Propionibacterium acnes, preferentially from at least one microorganism of the Propionibacterium acnes ATCC 6919 strain.

In another embodiment, the short-chain fatty acids according to the invention are contained in a conditioned culture medium (or supernatant) of at least one microorganism of the species Propionibacterium acnes , preferably of at least one microorganism of the Propionibacterium acnes ATCC 6919 strain.

A “culture supernatant”, also referred to as “conditioned culture medium”, is typically obtained by culturing the microorganism involved in a medium suitable for the survival and/or growth of the microorganism, then by separating the medium and the microorganism in order to harvest the medium brought into contact with the microorganism. Preferably, the culturing is carried out for a time and under conditions capable of allowing the microorganism to release, into the medium, the active agents which have the desired seborrhoeic properties, in particular the short-chain fatty acids (SCFAs) according to the invention.

The environment suitable for the survival and/or growth of the microorganism can be constituted of any nutritive medium suitable for the survival and/or culture of the microorganism. It generally contains a source of carbon and of nitrogen, such as for example amino acids, sugars, proteins, fatty acids, phosphates, sulfates, minerals and growth factors and vitamins, in appropriate amounts. For the purposes of the present application, the terms “conditioned culture medium” or “culture supernatant” are used without distinction to denote the entire culture supernatant obtained after culture of the microorganism in question, or any fraction or by-product of the supernatant, obtained by dialysis, fractionation, phase separation, filtration chromatography, affinity chromatography, precipitation, concentration, lyophilization, etc.

In the context of the present invention, the conditioned culture medium of at least one microorganism of the species Propionibacterium acnes according to the invention can be obtained by means of the process comprising the following steps: i) culturing at least one microorganism of the species Propionibacterium acnes such as Propionibacterium acnes ATCC 6919; ii) separating, in particular by centrifugation, the culture supernatant from the biomass; iii) recovering the culture supernatant; and iv) optionally stabilizing the culture supernatant, for example by filtration.

In the context of the present invention, the term “biomass” refers to the Propionibacterium acnes cells obtained after having carried out step i).

Preferably, the filtration is carried out with a syringe filter with a pore size of 0.45 pm.

SODIUM PROPIONATE

According to one particular embodiment, the short-chain fatty acid salt is sodium propionate. Sodium propionate has the following chemical structure:

[Chem 1]

It is sometimes used as a food additive, as a preservative in particular, under the code name E281.

It is water-soluble.

LONG-CHAIN FATTY ACIDS COMPRISING FROM 10 TO 24 CARBON ATOMS

More particularly, the long-chain fatty acids according to the invention comprise a linear or branched, saturated or unsaturated aliphatic chain containing 10 to 24 carbon atoms, preferably 16 to 18 carbon atoms;

According to one embodiment of the invention, the long-chain fatty acid comprises a linear and saturated aliphatic chain comprising from 16 to 18 carbon atoms.

According to one particular embodiment of the invention, the long-chain fatty acid is chosen from lauric acid, lauroleic acid, myristic acid, myristoleic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, dihydroxystearic acid, oleic acid, ricinoleic acid, elaidic acid, linoleic acid, alpha-linolenic acid, dihomo-gamma-linolenic acid, eleostearic acid, licanic acid, arachidonic acid, arachidic acid, eicosenoic acid, eicosapentaenoic acid, behenic acid, erucic acid, docosahexaenoic acid, and mixtures thereof.

According to an even more particular embodiment, the long-chain fatty acid is chosen from stearic acid and/or palmitic acid.

The long-chain fatty acid that is particularly preferred is palmitic acid.

By way of examples of long-chain fatty acids, mention may be made of the palmitic acid sold by Cayman Chemical (Ref. 10006627), the palmitic acid available under the trade name DUB GMS/MB from Stearinerie Dubois and the linoleic acid sold by Sigma (Ref. L1376).

COSMETIC COMPOSITION

A composition according to the invention comprises between 0.5% and 4% by weight of short-chain fatty acid salt, relative to the total weight of the composition, in particular between 1% and 3% by weight, even more particularly between 1.5% and 2.5% by weight. Thus, in particular, a composition according to the invention comprises between 0.5% and 4% by weight of sodium propionate, relative to the total weight of the composition, in particular between 1% and 3% by weight, even more particularly between 1.5% and 2.5% by weight.

In a preferred embodiment, a composition according to the invention comprises between 0.8% and 4% by weight of short-chain fatty acid salt, relative to the total weight of the composition, in particular between 0,8% and 3% by weight, even more particularly between 0,8% and 2.5% by weight.

Preferably, a composition according to the invention comprises between 0.8% and 4% by weight of sodium propionate, relative to the total weight of the composition, in particular between 0,8% and 3% by weight, even more particularly between 0,8% and 2.5% by weight.

According to one particular embodiment, a composition according to the invention comprises 2% of short-chain fatty acid salt, in particular of sodium propionate.

According to a preferred embodiment, a composition according to the invention comprises 0,8% of short-chain fatty acid salt, in particular of sodium propionate.

A composition according to the invention comprises between 0.1% and 5% by weight of long-chain fatty acid, relative to the total weight of the composition, in particular between 0.1% and 3% by weight, even more particularly between 0.5% and 2% by weight.

Thus, in particular, a composition according to the invention comprises between 0.1% and 5% by weight of palmitic acid, relative to the total weight of the composition, in particular between 0.1% and 3% by weight, even more particularly between 0.5% and 2% by weight. According to one particular embodiment, a composition according to the invention comprises 1% of long-chain fatty acid, in particular of palmitic acid.

In a preferred embodiment, a composition according to the invention comprises between 0.05% and 5% by weight of long-chain fatty acid, relative to the total weight of the composition, in particular between 0.1% and 3% by weight, even more particularly between 0.1% and 2% by weight.

Preferably, a composition according to the invention comprises between 0.1% and 5% by weight of palmitic acid, relative to the total weight of the composition, in particular between 0.1% and 3% by weight, even more particularly between 0.1% and 2% by weight. According to a preferred embodiment, a composition according to the invention comprises 0,1% of long-chain fatty acid, in particular of palmitic acid.

A composition according to the invention is generally suitable for topical application to keratin materials, in particular to the skin, and thus generally comprises a physiologically acceptable medium.

It is preferably a cosmetically acceptable medium, i.e. a medium which has a pleasant colour, odour and feel and which does not cause any unacceptable discomfort, i.e. stinging, tautness or redness, liable to discourage the user from applying this composition.

The compositions according to the invention comprise a fatty phase and an aqueous phase, as defined below. A composition according to the present invention is in particular in the form of an emulsion, notably in the form of an oil-in-water or water-in-oil emulsion, preferably in the form of an oil-in-water emulsion.

A composition according to the invention may be prepared according to the techniques that are well known to those skilled in the art.

According to one particular embodiment, the pH of the cosmetic composition according to the present invention is between 5.8 and 7.2, in particular between 6 and 7.

As indicated above, the maintaining of such a pH range has, inter alia, the advantage of limiting the risk of formation of acid odour that can be given off if propionic acid is formed, in particular for a pH below 5.5.

The composition according to the invention may comprise pH adjusters (acids or bases) for the purpose of maintaining the pH in this value range. Any pH adjuster conventionally suitable for a cosmetic application can be used in the context of the present application. Typically, mention may be made of citric acid, lactic acid, tartaric acid, oxalic acid, sodium hydroxide, HEPES, sodium citrate, potassium hydroxide and triethanolamine.

When the composition comprises such a pH adjuster, it is up to those skilled in the art to adjust the acid or base content in order to adjust the pH to preferentially between 6 and 7. The pHs can also be adjusted using the various pH adjusters mentioned above, depending on the gelling agents present in the composition according to the invention.

GELLING AGENTS

As indicated previously, the composition according to the invention comprises: iii)- at least one polymer chosen from polyacrylamides and 2-acrylamido-2- methylpropanesulfonic acid polymers and copolymers; and iv)- at least one carboxyvinyl polymer.

The gelling agents used in the context of the present invention are gelling agents of the aqueous phase. In this respect, they can be more particularly described as hydrophilic gelling agents.

For the purposes of the present invention, the term "hydrophilic gelling agent" means a compound that is capable of gelling the aqueous phase of the compositions according to the invention. The gelling agent is hydrophilic and is thus present in the aqueous phase of the composition. The gelling agent may be water-soluble or water-dispersible.

According to one particular embodiment of the invention, the aqueous phase of a composition according to the invention is gelled by 0.1% to 8% by weight of at least one hydrophilic gelling agent, relative to the total weight of the aqueous phase.

Preferably, the aqueous phase of a composition according to the invention is gelled by 0.5% to 8% by weight of at least one hydrophilic gelling agent, even more particularly by 0.8% to 4% by weight, notably for example by 0.8% to 3% by weight, relative to the total weight of the aqueous phase.

One of the hydrophilic gelling agents present in the composition according to the invention is chosen from (iii) a polymer chosen from polyacrylamides and 2-acrylamido-2- methylpropanesulfonic acid polymers and copolymers.

Polyacrylamides and 2-acrylamido-2-methylpropanesulfonic acid polymers and copolymers The polymers used that are suitable as aqueous gelling agent for the invention may be crosslinked or non-crosslinked homopolymers or copolymers including at least the 2- acrylamido-2-methylpropanesulfonic acid (AMPS^®) monomer, in a form partially or totally neutralized with a mineral base other than aqueous ammonia, such as sodium hydroxide or potassium hydroxide.

AMPS^® (monomer) is a trademark registered in the name of Lubrizol.

They are preferably totally or almost totally neutralized, i.e. at least 90% neutralized.

These AMPS polymers according to the invention may be crosslinked or non-crosslinked. When the polymers are crosslinked, the crosslinking agents may be chosen from the polyolefmically unsaturated compounds commonly used for crosslinking polymers obtained by radical polymerization.

Examples of crosslinking agents that may be mentioned include divinylbenzene, diallyl ether, dipropylene glycol diallyl ether, polyglycol diallyl ethers, triethylene glycol divinyl ether, hydroquinone diallyl ether, ethylene glycol or tetraethylene glycol di(meth)acrylate, trimethylolpropane triacrylate, methylenebisacrylamide, methylenebismethacrylamide, triallylamine, triallyl cyanurate, diallyl maleate, tetraallylethylenediamine, tetraallyloxyethane, trimethylolpropane diallyl ether, allyl (meth)acrylate, allylic ethers of alcohols of the sugar series, or other allyl or vinyl ethers of polyfunctional alcohols, and also the allylic esters of phosphoric and/or vinylphosphonic acid derivatives, or mixtures of these compounds.

According to a preferred embodiment of the invention, the crosslinking agent is chosen from methylenebisacrylamide, allyl methacrylate and trimethylolpropane triacrylate (TMPTA). The degree of crosslinking generally ranges from 0.01 mol% to 10 mol% and more particularly from 0.2 mol% to 2 mol% relative to the polymer.

The AMPS polymers that are suitable for use in the invention are water-soluble or water- dispersible. In this case, they are either “homopolymers” comprising only AMPS^® monomers and, if they are crosslinked, one or more crosslinking agents such as those defined above, or copolymers obtained from AMPS^® and one or more hydrophilic or hydrophobic ethylenically unsaturated monomers and, if they are crosslinked, one or more crosslinking agents such as those defined above. When said copolymers comprise hydrophobic ethylenically unsaturated monomers, these monomers do not comprise a fatty chain and are preferably present in small amounts.

For the purposes of the present invention, the term "fatty chain" means any hydrocarbon- based chain including at least 7 carbon atoms.

The term "water-soluble or water-dispersible" means polymers which, when introduced into an aqueous phase at 25°C, at a weight concentration equal to 1%, make it possible to obtain a macroscopically homogeneous and transparent solution, i.e. a solution with a maximum light transmittance value, at a wavelength equal to 500 nm, through a sample 1 cm thick, of at least 60% and preferably of at least 70%.

The "homopolymers" according to the invention are preferably crosslinked and neutralized, and they may be obtained according to the preparation process comprising the following steps: (a) the monomer such as AMPS^® is dispersed or dissolved in free form in a solution of tert-butanol or of water and tert-butanol; (b) the monomer solution or dispersion obtained in (a) is neutralized with one or more mineral or organic bases, preferably aqueous ammonia NFP, in an amount making it possible to obtain a degree of neutralization of the sulfonic acid functions of the polymer ranging from 90% to 100%; (c) the crosslinking monomer(s) are added to the solution or dispersion obtained in (b); (d) a standard free-radical polymerization is performed in the presence of free-radical initiators at a temperature ranging from 10°C to 150°C; the polymer precipitating in the tert-butanol-based solution or dispersion. The water-soluble or water-dispersible AMPS copolymers according to the invention contain water-soluble ethylenically unsaturated monomers, hydrophobic monomers, or mixtures thereof.

The water-soluble comonomers may be ionic or non-ionic.

Among the ionic water-soluble comonomers, mention may for example be made of the following compounds and salts thereof: (meth)acrylic acid, styrenesulfonic acid, vinylsulfonic acid and (meth)allylsulfonic acid, vinylphosphonic, maleic acid, itaconic acid, crotonic acid, water-soluble vinyl monomers of formula (A) below:

[Chem 2]

in which Ri is chosen from H, -CH₃,-C₂H₅ or -C₃H₇; Xi is chosen from alkyl oxides of type -OR₂ where R₂ is a linear or branched, saturated or unsaturated hydrocarbon-based radical containing from 1 to 6 carbon atoms, substituted with at least one sulfonic (-SO³ ) and/or sulfate (-SO⁴ ) and/or phosphate (-PO₄H₂-) group.

Among the non-ionic water-soluble comonomers, mention may for example be made of (meth)acrylamide, N-vinylacetamide and N-methyl N-vinylacetamide, N-vinylformamide and N-methyl-N-vinylformamide, maleic anhydride, vinylamine, N-vinyllactames comprising a cyclic alkyl group having from 4 to 9 carbon atoms, such as N- vinylpyrrolidone, N-butyrolactam and N-vinylcaprolactam, the vinyl alcohol of formula CH2=CHOH, the water-soluble vinyl monomers of formula (B) below:

[Chem 3]

in which R3 is chosen from H, -CH3, -C2H5 or -C3H7; X2 is chosen from alkyl oxides of the type -OR₄ where R₄ is a linear or branched, saturated or unsaturated hydrocarbon-based radical containing from 1 to 6 carbon atoms, optionally substituted with a halogen (iodine, bromine, chlorine or fluorine) atom; a hydroxyl (-OH) group; ether.

Mention is made, for example, of glycidyl (meth)acrylate, hydroxyethyl methacrylate, and (meth)acrylates of ethylene glycol, of diethylene glycol or of polyalkylene glycol.

Among the hydrophobic comonomers with no fatty chain, mention may for example be made of styrene and derivatives thereof such as 4 -butyl styrene, alpha-methylstyrene and vinyltoluene; vinyl acetate of formula CH2=CH-OCOCH3; vinyl ethers of formula

CH2=CHOR in which R is a linear or branched, saturated or unsaturated, hydrocarbon-based radical having from 1 to 6 carbons; acrylonitrile; caprolactone; vinyl chloride and vinylidene chloride; silicone derivatives, resulting, after polymerization, in silicone polymers such as methacryloxypropyltris(trimethylsiloxy)silane and silicone methacrylamides; the hydrophobic vinyl monomers of formula (C) below:

[Chem 4]

in which R4 is chosen from H, -CH3, -C2H5 or -C3H7; X3 is chosen from alkyl oxides of the type -OR5 where R5 is a linear or branched, saturated or unsaturated hydrocarbon-based radical containing from 1 to 6 carbon atoms.

Mention is made, for example, of methyl methacrylate, ethyl methacrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl acrylate, isobornyl acrylate and 2- ethylhexyl acrylate.

The water-soluble or water-dispersible AMPS polymers of the invention preferably have a molar mass ranging from 50 000 g/mol to 10 000 000 g/mol, preferably from 80 000 g/mol to 8 000 000 g/mol, and even more preferably from 100 000 g/mol to 7 000 000 g/mol.

As water-soluble or water-dispersible AMPS homopolymers suitable for use in the invention, mention may be made, for example, of crosslinked or non-crosslinked polymers of sodium acrylamido-2-methylpropanesulfonate, such as that used in the commercial product Simulgel 800 (CTFA name: Sodium Polyacryloyldimethyl Taurate), crosslinked ammonium acrylamido-2-methylpropanesulfonate polymers (INCI name: Ammonium Polyacryldimethyltauramide) such as those described in patent EP 0 815 928 B1 and such as the product sold under the trade name Hostacerin AMPS^® by the company Clariant. Preferably, a composition according to the invention comprises an AMPS^® homopolymer. As water-soluble or water-dispersible AMPS copolymers in accordance with the invention, examples that may be mentioned include:

- crosslinked acrylamide/sodium acrylamido-2-methylpropanesulfonate copolymers, such as that used in the commercial product Sepigel 305® by the company SEPPIC (CTFA name: Polyacrylamide/Ci3-Ci4 Isoparaffin/ Laureth-7) or that used in the commercial product sold under the name Simulgel 600 (CTFA: Acrylamide/sodium acryloyldimethyltaurate/isohexadecane/polysorbate-80) by the company SEPPIC;

- copolymers of AMPS^® and of vinylpyrrolidone or of vinylformamide, such as that used in the commercial product sold under the name Aristoflex AVC^® by Clariant (CTFA name: Ammonium Acryloyldimethyltaurate/VP copolymer) but neutralized with sodium hydroxide or potassium hydroxide;

- copolymers of AMPS^® and of sodium acrylate, such as, for example, the AMPS^®/sodium acrylate copolymer, such as that used in the commercial product sold under the name Simulgel EG^® by Seppic or under the trade name Sepinov EM (CTFA name: Hydroxy ethyl Acrylate/Sodium Acryloyldimethyltaurate Copolymer);

- copolymers of AMPS and of hydroxy ethyl acrylate, for instance the AMPS/hydroxy ethyl acrylate copolymer, such as that used in the commercial product sold under the name Simulgel NS^® by the company SEPPIC (CTFA name: Hydroxyethyl Acrylate/Sodium Acryloyldimethyltaurate Copolymer (And) Squalane (And) Polysorbate 60), or such as the product sold under the name Sodium Acrylamido-2-Methylpropanesulfonate/Hydroxy ethyl Acrylate Copolymer, such as the commercial product Sepinov EMT 10^® from Seppic (INCI name: Hydroxyethyl Aery late/S odium Acryloyldimethyltaurate Copolymer).

Mention may be made, as preferred water-soluble or water-dispersible AMPS^® homopolymers and copolymers in accordance with the invention, of crosslinked ammonium acrylamido-2-methylpropanesulfonate homopolymers (INCI name: Ammonium Polyacryldimethyltauramide), such as those described in patent EP 0 815 928 B1 and such as the product sold under the trade name Hostacerin AMPS^® by Clariant, crosslinked acrylamide/sodium acrylamido-2-methylpropanesulfonate copolymers, such as that used in the commercial product Sepigel 305^® from Seppic (CTFA name: Polyacrylamide/Ci3-Ci4 Isoparaffm/Laureth-7), or also copolymers of AMPS^® and of hydroxyethyl acrylate, such as the product sold under the name Sodium Acrylamido-2- Methylpropanesulfonate/Hydroxyethyl Acrylate Copolymer, such as the commercial product Sepinov EMT 10^® from Seppic (INCI name: Hydroxyethyl Acrylate/Sodium Acryloyldimethyltaurate Copolymer).

According to one preferred embodiment, the hydrophilic gelling agent iii) present in the composition according to the invention is chosen from crosslinked homopolymers of ammonium acrylamido-2-methylpropanesulfonate (INCI name: Ammonium Polyacryldimethyltauramide).

A composition according to the invention comprises from 0.1% to 8% by weight as solids, preferably from 0.2% to 5% by weight and more preferentially from 0.5% to 3% by weight of polyacrylamides and of 2-acrylamido-2-methylpropanesulfonic acid polymers and copolymers, relative to the total weight of the composition.

The other hydrophilic gelling agent present in the composition according to the invention is chosen from (iv) at least one modified or unmodified, preferably unmodified, carboxyvinyl polymer.

Carboxyvinyl polymers

The modified or unmodified carboxyvinyl polymers can be copolymers resulting from the polymerization of at least one monomer (a) chosen from a,b-ethylenically unsaturated carboxylic acids or their esters, with at least one ethylenically unsaturated monomer (b) comprising a hydrophobic group.

The term "copolymers" means both copolymers obtained from two types of monomer and those obtained from more than two types of monomer, such as terpolymers obtained from three types of monomer.

Their chemical structure more particularly comprises at least one hydrophilic unit and at least one hydrophobic unit. The term “hydrophobic group” or “hydrophobic unit” is understood to mean a radical having a saturated or unsaturated and linear or branched hydrocarbon-based chain, comprising at least 8 carbon atoms, preferably from 10 to 30 carbon atoms, in particular from 12 to 30 carbon atoms and more preferentially from 18 to 30 carbon atoms.

Preferably, these copolymers are chosen from copolymers derived from the polymerization:

- of at least one monomer of formula (1) below:

[Chem 6]

in which Ri denotes H or CH₃ or C₂H₅, i.e. acrylic acid, methacrylic acid or ethacrylic acid monomers, and

- of at least one monomer corresponding to the monomer of following formula (2):

[Chem 7] C H₂ _ C — C — GR_g

F¾2 O

(2) in which R denotes H or CH or C H (that is to say, acrylate, methacrylate or ethacrylate units) and preferably H (acrylate units) or CH (methacrylate units), and R is a hydrogen atom. According to a preferred embodiment, these polymers are crosslinked.

Among the copolymers of this type, that will be used more particularly are polymers derived from the polymerization of a monomer mixture comprising:

- essentially acrylic acid,

- a compound of formula (2) described above in which R denotes H or CH₃, and R is a hydrogen atom,

- a crosslinking agent, which is a well-known copolymerizable unsaturated polyethylenic monomer, for instance diallyl phthalate, allyl (meth)acrylate, divinylbenzene, (poly)ethylene glycol dimethacrylate and methylenebisacrylamide.

According to a specific embodiment of the invention, the carboxyvinyl polymers employed in the context of the present invention are unmodified. They are in particular homopolymers. Among the carboxyvinyl polymers, mention may also be made of sodium polyacrylates such as those sold under the name Cosmedia SP^® containing 90% solids and 10% water, or Cosmedia SPL^® as an inverse emulsion containing about 60% solids, an oil (hydrogenated polydecene) and a surfactant (PPG-5 Laureth-5), both sold by the company BASF.

Mention may also be made of partially neutralized sodium polyacrylates that are in the form of an inverse emulsion comprising at least one polar oil, for example the product sold under the name Luvigel^® EM by the company BASF.

The modified or unmodified carboxyvinyl polymers may also be chosen from crosslinked (meth)acrylic acid homopolymers.

For the purposes of the present application, the term “( meth)acrylic ” is understood to mean “ acrylic or methacrylic” .

Examples that may be mentioned include the products sold by Lubrizol under the names Carbopol 910, 934, 940, 941, 934 P, 980, 981, 2984 and 5984, or by 3V-Sigma under the name Synthalen^® K, Synthalen^® L or Synthalen^® M.

According to another specific embodiment of the invention, mention may be made, among the carboxyvinyl polymers, of crosslinked acrylic acid homopolymers. Mention may in particular be made, among the carboxyvinyl polymers which can more particularly be employed in the context of the present invention, of Carbopol (CTFA name: carbomer) sold by Lubrizol. Among the homopolymers of this type, mention may be made of those crosslinked with an allyl alcohol ether of the sugar series, for instance the products sold under the names Carbopol 980, 981, 954, 2984 and 5984 by the company Lubrizol or the products sold under the names Synthalen M and Synthalen K by the company 3 V.

Such acrylic homopolymers may be present in the composition in a particulate or non-particulate form. When they are present in a particulate form, their mean size in the hydrated state is preferably less than or equal to 10 pm and even more preferentially less than or equal to 5 pm. Their mean size in the dry or non-hydrated state is preferably less than or equal to 2 pm, preferably less than or equal to 1 pm.

Preferably, the acrylic acid homopolymer is present in non-particulate form.

Preferably, use is made of an at least partially neutralized acrylic acid homopolymer. The homopolymer used according to the invention may be chosen in particular from sodium polyacrylates and potassium polyacrylates. Sodium polyacrylate is preferably used.

As regards these acrylic polymers already neutralized before use, examples that may be mentioned include:

- sodium polyacrylates such as those sold under the name Cosmedia SP® containing 90% solids and 10% water, or Cosmedia SPL® as an inverse emulsion containing about 60% dry active material, an oil (hydrogenated polydecene) and a surfactant (PPG-5 laureth-5), both sold by the company BASF;

- partially neutralized sodium polyacrylates, notably in the form of an inverse emulsion comprising at least one polar oil, for example the product sold under the name Luvigel® EM sold by the company BASF; and

- mixtures thereof.

According to one preferred embodiment, the carboxyvinyl polymers, more particularly unmodified carboxyvinyl polymers, iv) present in the composition according to the invention are chosen from sodium polyacrylates sold under the name Cosmedia SP^® contenant 90% of solids and 10% of water.

The carboxyvinyl polymers are present in a proportion of from 0.1% to 5% by weight of solids relative to the weight of the aqueous phase, in particular from 0.2% to 3% by weight and preferably between 0.3% and 1% by weight, relative to the weight of the aqueous phase.

According to one particularly preferred embodiment of the invention, the composition according to the invention comprises the hydrophilic gelling agent iii) is chosen from crosslinked polymers of ammonium acrylamido-2-methylpropanesulfonate and the hydrophilic gelling agent iv) is chosen from sodium polyacrylates.

According to one embodiment of the invention, the polymers iii) and iv) are present in a total content of from 0.5% 10% by weight relative to the total weight of the composition, in particular from 1.0% to 5% by weight, even more particularly from 1.5% to 4% by weight and, according to one embodiment of the invention, the polymers iii) and iv) are present in a polymers iii)/iv) weight ratio of between 2 and 5, more particularly between 2, 5 and 4, and is preferably 3/1.

Additional gelling agents may also be present in the composition according to the present invention. It is a matter of routine practice for those skilled in the art to adjust the nature and the amount of such additional gelling agents present in the compositions in accordance with the invention such that the desired cosmetic properties thereof are not thereby affected.

AQUEOUS PHASE

The compositions according to the invention contain at least one aqueous phase.

The aqueous phase is present in a composition according to the invention in a content ranging from 40% to 90% by weight, preferably from 50% to 80% by weight, and more preferentially from 55% to 75% by weight, relative to the total weight of said composition.

The aqueous phase comprises water and optionally a water-soluble solvent.

According to the present invention, the term “ water-soluble solvent ’ is intended to denote a compound that is liquid at ambient temperature and water-miscible (miscibility with water of greater than 50% by weight at 25°C and atmospheric pressure).

The water-soluble solvents which can be used in the composition of the invention can in addition be volatile.

Among the water-soluble solvents that may be used in the composition according to the invention, mention may be made notably of lower monoalcohols containing from 1 to 5 carbon atoms such as ethanol and isopropanol, glycols containing from 2 to 8 carbon atoms such as ethylene glycol, hexylene glycol, propylene glycol, 1,3-butylene glycol and dipropylene glycol, C3 and C4 ketones and C2-C4 aldehydes. According to an alternative embodiment, the aqueous phase of a composition according to the invention may comprise at least one C2-C32 polyol.

For the purposes of the present invention, the term “ polyoF should be understood as meaning any organic molecule including at least two free hydroxyl groups.

Preferably, a polyol in accordance with the present invention is present in liquid form at ambient temperature.

A polyol that is suitable for use in the invention may be a compound of linear, branched or cyclic, saturated or unsaturated alkyl type, bearing on the alkyl chain at least two -OH functions, in particular at least three -OH functions and more particularly at least four -OH functions.

The polyols that are suitable for formulating a composition according to the present invention are in particular those notably containing from 2 to 32 carbon atoms, preferably from 3 to 16 carbon atoms.

The polyol may be chosen, for example, from ethylene glycol, pentaerythritol, trimethylolpropane, propylene glycol, dipropylene glycol, 1,3 -propanediol, butylene glycol, isoprene glycol, pentylene glycol, hexylene glycol, caprylyl glycol, glycerol, polyglycerols, such as glycerol oligomers, for instance diglycerol, polyethylene glycols, and mixtures thereof.

According to a preferred embodiment of the invention, said polyol is chosen from ethylene glycol, pentaerythritol, trimethylolpropane, propylene glycol, dipropylene glycol, caprylyl glycol, glycerol, polyglycerols and polyethylene glycols, and mixtures thereof.

According to one preferred embodiment, the composition of the invention comprises at least glycerol.

FATTY PHASE

The compositions according to the invention contain at least one water-immiscible organic liquid phase, termed fatty phase.

Such a fatty phase is thus included in a content ranging from 10% to 40% by weight, relative to the total weight of the composition, notably from 20% to 30% by weight.

The fatty phase generally comprises one or more hydrophobic compounds which render said phase water-immiscible. This phase is liquid (in the absence of structuring agent) at ambient temperature (20-25°C). Preferentially, the water-immiscible organic liquid phase according to the invention comprises at least one volatile oil and/or one non-volatile oil and optionally at least one structuring agent.

In the context of the present invention, the term “oil” means a fatty substance that is liquid at ambient temperature (25°C) and atmospheric pressure (760 mmHg, i.e. 1.05><10⁵ Pa).

The oil can be chosen from any physiologically acceptable oil and particularly cosmetically acceptable oil, in particular mineral, animal, plant or synthetic oils; in particular, volatile or non-volatile hydrocarbons and/or silicone and/or fluorinated oils, and mixtures thereof.

As examples of oils that can be used in the invention, mention may be made of: i) hydrocarbon-based plant oils such as liquid triglycerides of fatty acids comprising 4 to 24 carbon atoms, such as caprylic/capric acid triglycerides such as those sold by the company Stearineries Dubois or those sold under the names Miglyol 810, 812 and 818 by Dynamit Nobel, and jojoba oil; ii) linear or branched hydrocarbons of mineral or synthetic origin, such as liquid paraffins and derivatives thereof, petroleum jelly, polydecenes, polybutenes, hydrogenated polyisobutene such as Parleam, squalane, branched-chain hydrocarbon-based oils comprising from 10 to 20 carbon atoms, such as isohexadecane or isododecane; iii) synthetic ethers containing from 10 to 40 carbon atoms; iv) any synthetic esters, such as isononyl isononanoate, isopropyl myristate, isopropyl palmitate, Cnto C15 alkyl benzoate, silicone oils such as non-volatile poly dimethyl siloxanes (PDMSs) which may be linear (dimethicones) or cyclic (cyclomethicones); v) lipophilic derivatives of amino acids, such as isopropyl lauroyl sarcosinate (INCI: Isopropyl Lauroyl sarcosinate) sold under the name Eldew SL 205 by the company Ajinomoto;

- fatty alcohols containing from 8 to 26 carbon atoms, for instance cetyl alcohol, stearyl alcohol, the mixture of cetyl alcohol and of stearyl alcohol (cetylstearyl alcohol), oleyl alcohol or linoleyl alcohol, and vi) mixtures thereof.

In one particular embodiment according to the invention, the oily phase of the composition comprises oils chosen from branched-chain hydrocarbon-based oils comprising from 10 to 20 carbon atoms, such as isohexadecane, fatty alcohols containing from 8 to 26 carbon atoms, such as cetyl alcohol and/or stearyl alcohol, and mixtures thereof. SURFACTANTS

The emulsions also contain at least one emulsifying surfactant chosen from amphoteric, anionic, or non-ionic emulsifiers, used alone or as a mixture, and optionally a coemulsifier. The emulsifiers are chosen in an appropriate manner according to the emulsion to be obtained (water-in-oil or oil-in-water).

By way of example as emulsifying surfactants, mention may be made of fatty acid esters of polyethylene glycol.

The fatty acid ester of polyethylene glycol present in the composition according to the invention is preferably a C16-C22 fatty acid ester comprising from 8 to 100 ethylene oxide units.

The fatty chain of the esters may be chosen especially from stearyl, behenyl, arachidyl, palmityl and cetyl units, and mixtures thereof, such as cetearyl, and preferably a stearyl chain.

The number of ethylene oxide units may range from 8 to 100, preferably from 10 to 80, better still from 10 to 50. According to a particular embodiment of the invention, this number may range from 20 to 40.

As examples of fatty acid esters of polyethylene glycol, mention may be made of stearic acid esters respectively comprising 20, 30, 40, 50 and 100 ethylene oxide units, such as the products respectively sold under the names Myrj 49 P (polyethylene glycol 20 EO stearate; CTFA name: PEG-20 stearate), Myrj 51, Myrj 52 P (polyethylene glycol 40 EO stearate; CTFA name: PEG-40 stearate), Myrj 53 and Myrj 59 P by the company Croda.

The fatty acid ester of polyethylene glycol may be present in the composition according to the invention in a content ranging from 0.1% to 10% by weight, preferably ranging from 0.1% to 5% by weight and preferentially ranging from 0.1% to 3% by weight, relative to the total weight of the composition.

By way of example as additional emulsifying surfactant mention may be made of C16-C22 fatty acid esters of sorbitol and C16-C22 fatty acid esters of glycerol.

The C16-C22 fatty acid esters of sorbitan are formed by esterification with sorbitol of at least one fatty acid comprising at least one saturated or unsaturated linear alkyl chain respectively having from 16 to 22 carbon atoms. These esters may be chosen especially from sorbitan stearates, behenates, arachidates, palmitates or oleates, and mixtures thereof. Use is preferably made of sorbitan stearates and palmitates, and preferably sorbitan stearates.

The C16-C22 fatty acid ester of sorbitan present in the composition according to the invention is advantageously solid at a temperature of less than or equal to 45°C.

As examples of sorbitan esters that may be used in the composition according to the invention, mention may be made of sorbitan monostearate (CTFA name: Sorbitan stearate), sold by the company Croda under the name Span 60, sorbitan tristearate, sold by the company Croda under the name Span 65 V, sorbitan monopalmitate (CTFA name: Sorbitan palmitate), sold by the company Croda under the name Span 40, sorbitan monooleate, sold by the company Croda under the name Span 80 V, and sorbitan trioleate, sold by the company Uniqema under the name Span 85 V. Preferably, the sorbitan ester used is sorbitan tristearate.

The C16-C22 fatty acid ester of sorbitan may be present in the composition according to the invention in a content ranging from 0.01% to 10% by weight, preferably ranging from 0.01% to 5% by weight and preferentially ranging from 0.1% to 3% by weight, relative to the total weight of the composition.

The fatty acid ester of glycerol may be obtained in particular from an acid comprising a saturated linear alkyl chain containing from 16 to 22 carbon atoms. Fatty acid esters of glycerol that may in particular be mentioned include glyceryl stearate (glyceryl mono-, di- and/or tristearate) (CTFA name: Glyceryl stearate) or glyceryl ricinoleate, and mixtures thereof. Preferably, the fatty acid ester of glycerol used is chosen from glyceryl stearates.

It may also be a mixture of glyceryl mono/di stearate (36/64)/potassium stearate having the INCI name glyceryl stearate SE sold under the name Tegin Pellets by the company Evonik Goldschmidt.

The fatty acid ester of glycerol may be present in an amount ranging from 0.1% to 10% by weight, preferably ranging from 0.1% to 5% by weight and preferentially ranging from 0.1% to 3% by weight, relative to the total weight of the composition.

The composition of the invention may in particular be a mixture of glyceryl stearate and of polyethylene glycol 100 EO monostearate and in particular that comprising a 50/50 mixture sold under the name Arlacel 165 by the company Croda. In one particular embodiment, the composition according to the invention comprises at least one surfactant chosen from a fatty acid ester of polyethylene glycol, C16-C22 fatty acid esters of sorbitan, and C16-C22 fatty acid esters of glycerol, and mixtures thereof.

ADDITIVES

A composition according to the invention may also comprise at least one additive chosen from the usual adjuvants in the cosmetics field, such as preservatives, fragrances, colorants, polar additives, chelating agents.

Needless to say, those skilled in the art will take care to select this or these optional additional compound(s), and/or the amount thereof, such that the advantageous properties of a composition according to the invention are not, or are not substantially, adversely affected by the envisioned addition.

The composition according to the invention may also comprise other active constituents, such as desquamating agents, depigmenting or propigmenting agents, anti-glycation, anti inflammatory or calmative agents, healing agents, moisturisers, humectants, anti-pollution agents, anti-ageing agents, agents which stimulate dermal or epidermal macromolecule synthesis and/or which prevent degradation thereof, agents which stimulate fibroblast and/or keratinocyte proliferation or which stimulate the keratinocyte differentiation, dermo- relaxing agents, tensioning agents, agents which act on the microcirculation, agents which act on cell energy metabolism, mattifying agents, UV-screening agents, odour absorbers, or mixtures thereof.

According to one preferred embodiment, a composition according to the invention also comprises at least one additional cosmetic active agent, in particular at least two additional cosmetic active agents and preferably at least three additional cosmetic active agents, other than the short-chain fatty acid salt and the long-chain fatty acid, in particular other than sodium propionate and palmitic acid.

As active agent, mention may in particular be made of retinol, also known as vitamin A. For the purposes of the present invention, the term “retinol” denotes any retinol isomers, in particular all-trans-retinol, 13-cis retinol, 11-cis retinol, 9-cis retinol and 3,4- didehydroretinol. In particular, all-trans-retinol may be used in the compositions according to the invention.

In particular, the additional cosmetic active agent may be at least one hydrophilic active agent.

The term “hydrophilic active agent” is intended to mean a water-soluble or water-dispersible active agent, capable of forming hydrogen bonds.

As hydrophilic active agents, examples that may be mentioned include moisturizers, depigmenting agents, desquamating agents, humectants, anti-ageing agents; mattifying agents, healing agents, antibacterial agents, and mixtures thereof.

The additional hydrophilic active agent(s) may notably be chosen from: vitamins and derivatives thereof, notably niacinamide (vitamin B3); humectants, for instance urea, hydroxyureas, glycerol, polyglycerols, glyceryl glucoside, diglyceryl glucoside, polyglyceryl glucosides and xylityl glucoside, and in particular glycerol;

- C-glycoside compounds such as, for example, the C-glycoside compounds described in document WO 02/051828, and notably a C-glycoside suitable for the invention is C-beta-D- xylopyranoside-2-hydroxypropane, the INCI name of which is Hydroxypropyl Tetrahydropyrantriol, notably sold under the name Mexoryl SBB^® or Mexoryl SCN^® by Chimex; antioxidant compounds; in addition particularly anti-ageing active agents, such as hyaluronic acid compounds, and notably sodium hyaluronate, salicylic acid compounds and in particular 5- n-octanoylsalicylic acid (capryloylsalicylic acid), adenosine, C-P-D-xylopyranoside-2- hydroxypropane and the sodium salt of (3-hydroxy-2-pentylcyclopentyl)acetic acid; and mixtures thereof.

According to another particular embodiment, the composition according to the invention, in addition to its abilities to promote sebum secretion, also allows moisturization of the skin.

INTENDED USE OF THE COMPOSITION

A composition according to the invention may be in the form of a cosmetic composition for caring for keratin materials, in particular the skin, preferably a cosmetic composition for caring for the body or the face, preferably the face. These compositions can constitute gels for protecting, treating or caring for the face, for the hands or for the body, for example gels for daytime or nighttime application, or protective or care body gels.

In particular, a composition of the invention may be in the form of an anti-ageing care composition for the skin of the body or of the face, in particular of the face.

Thus, the invention also relates to the use of a composition according to the invention for caring for keratin materials, in particular the skin, preferably for caring for in particular the skin of the body and/or of the face.

The invention also relates to a cosmetic process for caring for keratin materials, in particular the skin, comprising at least one step of applying a composition as defined previously to said keratin materials.

In particular, a composition according to the invention may be used for combating dry skin. Dry skin

Dry skin manifests itself essentially in a sensation of discomfort, such as pulling and/or tautness. Said dry skin is also rough to the touch and/or appears to be covered with squamae. When the skin is slightly dry, the squamae are abundant but barely visible to the naked eye. They become less and less numerous, but increasingly visible to the naked eye, when this disorder worsens.

The cause of this skin dryness may be of constitutional or acquired type.

In one particular embodiment, the composition according to the invention is used for treating and/or preventing non-pathological constitutional dry skin or non-pathological acquired dry skin.

In the case of acquired dry skin, the involvement of external parameters such as exposure to chemical agents, to inclement climatic conditions or the sun, or else certain therapeutic treatments (with retinoids, for example) are determining factors. Under these external influences, the skin may then become momentarily and locally dry.

Non-pathological constitutional dry skin is dry skin the severity of which may be dependent on the external factors already indicated. Included in this skin category, termed dry skin, are senile skin (characterized by a general decrease in skin metabolism with age), fragile skin (very sensitive to external factors and often accompanied by erythema and rosacea) and common xerosis (of probable genetic origin and manifesting itself mainly on the face, the limbs and the back of the hands).

The composition according to the invention thus proves to be particularly effective for preventing and/or treating dry skin, and more particularly acquired dry skin and/or constitutional dry skin.

Non-pathological acquired constitutional dry skin can be characterized by a deficiency in lipids constituting the hydro-lipid barrier and/or film, in particular an endogenous insufficiency of sebum production by the sebaceous glands.

As mentioned above, a sebum content of less than 100 pg/crrf, measured in the T zone of the face by the method described in FR 2 368 708, can be considered as characteristic of hyposeborrhoeic dry skin.

A composition according to the invention thus proves to be particularly effective for preventing and/or treating hyposeborrhoeic dry skin.

In particular, a composition according to the invention may be used for the purpose of combating the signs of skin ageing, in particular by promoting sebum production in aged skin, notably of more than 60 years old, or even more than 65 years old.

Thus, the present application also relates to the use of a composition according to the invention for combating the signs of skin ageing.

Aged skin

The composition according to the invention proves to be particularly effective for preventing and/or treating aged skin, and more particularly hyposeborrhoeic aged skin. As mentioned above, premature ageing is known to be attributed to the absence or the insufficiency of sebum at the skin surface.

The term "aged skin" is intended to mean a general aesthetic state of the skin resulting from chronological ageing and/or from photoinduced ageing.

More particularly, the present invention is directed towards preventing and/or reducing and/or treating the signs of skin ageing.

The term "signs of skin ageing" is intended to mean any modification of the external appearance of the skin due to ageing of chronological and/or photo-induced origin.

By way of example of this modification considered in the invention, mention may be made of a surface that is not very homogeneous and is less smooth, a thinned epidermis, wrinkles and fine lines, wizened skin, a lack of elasticity and/or of tone of the skin, resulting in the appearance of flaccid, wrinkled skin.

In particular, the signs of skin ageing targeted by the invention are chosen from a thinning of the skin, a loss of firmness, a loss of elasticity, a loss of density or a loss of skin tone, an alteration of the appearance of the surface of the skin, the appearance of a marked microrelief of the skin, the appearance of roughness, the formation and/or the presence of fine lines and/or wrinkles, a change in the radiance of the complexion, a wizened appearance of the skin, sagging skin or withering of the skin.

Preferably, the signs of skin ageing targeted by the invention are chosen from thinning of the skin, the appearance of a marked microrelief of the skin, the formation and/or the presence of fine lines and/or wrinkles, sagging of the skin and withering of the skin.

More preferentially, the signs of skin ageing targeted by the invention are chosen from the appearance of a marked microrelief of the skin, the formation and/or the presence of fine lines and/or wrinkles, sagging of the skin and withering of the skin.

The composition may be applied to the skin by hand or using an applicator.

Throughout the description, including the claims, the expression “comprising a” should be understood as being synonymous with “comprising at least one”, unless otherwise specified. The expressions “between... and...”, “comprises from ... to...”, “formed from ... to...” and “ranging from... to...” should be understood as being inclusive of the limits, unless otherwise specified.

The invention is illustrated in greater detail by the examples and figures presented below. Unless otherwise indicated, the amounts shown are expressed as weight percentages.

Example

Measurement and evaluation methods

Stability measurement

The stability of the compositions is evaluated at T = 2 months, at 45°C. It is verified whether phase separation, release or a change in appearance is observed.

Appearance The appearance of the composition obtained is evaluated:

- by observation of its behaviour from the viewpoint of its viscoelastic properties and its stability, and by measurement of the viscosity.

Protocol for measuring the viscosity

The viscosity of the formulas was measured using a rheometer (Rheomat RM 200, Lamy Rheology) with the spindle 4 (2 to 23 Pa.s) at a speed of 200 rpm. The measurements are expressed in Pa.s.

Production process for limiting the formation of unpleasant acid odour

Regardless of the polymeric or gelling system used, the cosmetic composition is preferably prepared in several steps:

1.Phase B is mixed in the production tank and heated to 75°C at an outer paddle speed of 20 rpm and an inner paddle speed of 120 rpm.

2. The constituents of phase A are heated to 75°C in a separate jacketed beaker, in a deflocculator.

3. The polymers are dispersed in isohexadecane at ambient temperature in a 1000 ml stainless steel beaker in a deflocculator.

4. A is emulsified in B at 75°C, tank open, at an outer paddle speed of 60 rpm, an inner paddle speed of 120 rpm and a turbine speed of 1000 rpm.

5. Phase D (phase of polymers dispersed at ambient temperature in a deflocculator) is added at a maximum of 65°C, and the mixture is homogenized until a smooth, shiny formula is obtained.

6. Phase E is added at 40°C.

7. The pH of the phase containing the sodium propionate is adjusted to a pH of between 6.3 and 6.6.

Example 1: Preparation of a composition in the form of an oil-in-water emulsion

An oil-in-water emulsion 1 according to the invention is prepared using the weight proportions as detailed in the table below. The values are expressed as weight percentages relative to the total weight of the composition.

[Table 1]

An oil-in-water emulsion 2 according to the invention is prepared using the weight proportions as detailed in the table below. The values are expressed as weight percentages relative to the total weight of the composition. [Table 2]

An oil-in-water emulsion 3 according to the invention is prepared using the weight proportions as detailed in the table below. The values are expressed as weight percentages relative to the total weight of the composition. [Table 3]

The mixture of ammonium polyacryldimethyltauramide, ammonium polyacryldimethyltauramide and sodium polyacrylate used in compositions 1, 2 and 3 to the invention makes it possible to obtain an appropriate and stable composition.

Counterexample 1

A composition is prepared with different an acrylates/Cio-C3o alkyl acrylate crosspolymer gelling agent, for instance Ultrez 20^® or Pemulen TR21^® sold by Lubrizol. [Table 4]

Although it is known to be resistant to salts, the acrylic polymer that is hydrophobically modified (with C10-C30 alkyl chains) is not compatible with the obtaining of a composition in the form of an oil-in-water emulsion comprising sodium propionate and palmitic acid, which is suitable and stable over time.

Counterexample 2

The composition is prepared with a polymer different from those according to the invention, a hydroxyethylcellulose gelling agent such as, for example, that sold under the trade name Natrosol 250 HHR CS by the company Ashland.

[Table 5]

The hydroxy ethylcellulose is not compatible with the obtaining of a composition in the form of an oil-in-water emulsion comprising sodium propionate and palmitic acid.

Claims

Claims

1. Composition, in particular cosmetic composition, in particular for caring for keratin materials, in particular the skin, comprising: i)- between 0.5% and 4% by weight of short-chain fatty acid salt, comprising a linear or branched, saturated or unsaturated aliphatic chain containing 3 to 8 carbon atoms, preferably 3 to 5 carbon atoms, relative to the total weight of the composition, and ii)- at least one long-chain fatty acid salt, comprising a linear or branched, saturated or unsaturated aliphatic chain containing 10 to 24 carbon atoms, preferably 16 to 18 carbon atoms; iii)- at least one polymer chosen from polyacrylamides and 2-acrylamido-2- methylpropanesulfonic acid polymers and copolymers; and iv)- at least one carboxyvinyl polymer.

2. Composition according to Claim 1, characterized in that the short-chain fatty acid salt is chosen from a salt of propionic acid, of butyric acid, of valeric acid or of a mixture thereof, it being possible for the salt to be chosen from calcium salts, sodium salts, magnesium salts and potassium salts, and more particularly sodium salts, in particular sodium propionate.

3. Composition according to Claim 1 or 2, characterized in that the short-chain fatty acid salt, in particular the sodium propionate, is present in a content of between 1% and 3% by weight relative to the total weight of the composition, notably between 1.5% and 2.5% by weight.

4. Composition according to any one of Claims 1 to 3, characterized in that the polymer iii) is chosen from crosslinked polymers of ammonium acrylamido-2- methylpropanesulfonate, and mixtures thereof.

5. Composition according to any one of Claims 1 to 4, characterized in that the polymer iv) is chosen from sodium polyacrylates and mixtures thereof.

6. Composition according to any one of the preceding claims, characterized in that said polymers iii) and iv) are present in a total content of from 0.5% to 10% by weight relative to the total weight of the composition, in particular from 1.0% to 5% by weight, even more particularly from 1.5% to 4% by weight.

7. Composition according to any one of the preceding claims, characterized in that the long-chain fatty acid is palmitic acid.

8. Composition according to any one of the preceding claims, characterized in that the long-chain fatty acid, in particular the palmitic acid, is present in a content of between 0.1% and 5% by weight relative to the total weight of the composition, notably between 0.1% and 3%, in particular between 0.5% and 2% by weight.

9. Composition according to the preceding claim, characterized in that the pH of the cosmetic composition according to the present invention is between 5.8 and 7.2, in particular between 6 and 7.

10. Composition according to any one of the preceding claims, characterized in that it is in the form of an emulsion, notably in the form of an oil-in-water or water-in-oil emulsion, preferably an oil-in-water emulsion.

11. Composition according to the preceding claim, characterized in that the oily phase comprises oils chosen from branched-chain hydrocarbon-based oils comprising from 10 to 20 carbon atoms, such as isohexadecane, fatty alcohols containing from 8 to 26 carbon atoms, such as cetyl alcohol and/or stearyl alcohol, and mixtures thereof.

12. Composition according to Claim 10 or 11, characterized in that it comprises at least one surfactant chosen from a fatty acid ester of polyethylene glycol, C16-C22 fatty acid esters of sorbitan, and C16-C22 fatty acid esters of glycerol, and mixtures thereof.

13. Composition according to any one of the preceding claims, characterized in that it also comprises at least one additional cosmetic active agent, in particular at least two additional cosmetic active agents and preferably at least three additional cosmetic active agents, other than the short-chain fatty acid salt and than the long-chain fatty acid, in particular other than sodium propionate and palmitic acid.

14. Composition according to any one of the preceding claims, characterized in that it is a cosmetic composition for caring for keratin materials, in particular the skin, preferably a cosmetic composition for caring for the body or the face, preferably the face.

15. Cosmetic process for caring for keratin materials, in particular the skin, comprising at least one step of applying a composition as defined according to any of the preceding claims to said keratin materials.