Cosmetic composition comprising an elastic mixture based on modified chitosan

Abstract

Cosmetic composition comprising a modified chitosan-based elastic mixture. The invention relates to a cosmetic composition comprising a mixture capable of forming an elastic film comprising: at least one chitosan-derived polysaccharide including amide and carboxylic acid groups, at least one natural or modified polysaccharide, different from the chitosan-derived polysaccharide, and at least one polyol, which provides a tightening effect and deforms elastically to follow the movements and mechanical deformations of the skin surface. The present invention also relates to a method for preparing a cosmetic composition according to the invention, as well as a skincare method comprising a step of applying a cosmetic composition according to the invention to the skin.

Description

Title of the invention: Cosmetic composition comprising an elastic mixture based on modified chitosan. Technical field

[0001] The present invention relates to the cosmetic field, and more particularly to a cosmetic composition comprising a mixture capable of forming an elastic film, which provides a tightening effect and deforms elastically to follow the movements and mechanical deformations of the skin surface. The present invention also relates to a method for preparing a cosmetic composition according to the invention, as well as a skincare method comprising a step of applying a cosmetic composition according to the invention to the skin.

[0002] Communicating anti-wrinkle effects with immediate and lasting skin smoothing is a key asset and a powerful driver of innovation and consumer satisfaction. Currently, the immediate anti-wrinkle smoothing effect is primarily achieved through the incorporation of contractile film-forming polymers, known for their tightening effect. However, the effectiveness of these polymers is very limited, either due to their durability (the polymer film cracks) and lack of comfort, or due to an ineffective smoothing effect (the comfort / tightening effect paradox is not achieved). Furthermore, to date, the smoothing effect provided by tightening polymers is insufficient compared to consumer expectations and does not last for a sufficient duration.

[0003] The Applicant has already described in application WO 2013 / 167835 a cosmetic treatment providing a tightening and smoothing effect comprising a specific elastic complex made up of at least one gelling or thickening starch, at least one polyol, and at least one polymer selected from polyvinyl alcohols, vinylpyrrolidone polymers and copolymers, and latex. However, these compositions have the disadvantage of being too sticky; they also lack adhesion to the skin (peelability problem).

[0004] The inventors have now developed a cosmetic composition comprising a mixture of specific compounds capable of forming an elastic film with an immediate, visible, and lasting smoothing effect. The film thus formed can deform reversibly, so that after deformation, for example after stretching, it returns to the state it had before the application of the mechanical stress provided, for example by deformation of the skin. The film formed by the cosmetic composition comprising said mixture has greater resistance to breakage, which makes it possible to maintain the mechanical properties of the film formed on the skin surface intact. Once incorporated into a cosmetic composition, the mixture capable of forming this The elastic film has a combined tightening and enhanced elastic effect, capable of following the skin's movements without cracking. The resulting effect is comparable to a sheathing effect, as the cosmetic composition of the invention provides elasticity to skin naturally subjected to deformations, such as changes in facial expression or contact with hands or clothing. The inventors have thus succeeded in developing a cosmetic composition capable of combining performance characteristics that are difficult to reconcile: a tightening effect combined with an elastic effect, resolving the tightening / elasticity paradox. The new cosmetic composition is capable of effectively smoothing the skin's surface, notably achieving partial or total erasure of wrinkles, including medium and deep wrinkles.

[0005] The cosmetic composition of the invention exhibits remarkable skin-tightening and elastic properties, which are linked to the combination of polymers selected for their contraction properties with elastic polymers (elastic properties optimized by association with a polyol plasticizer). These properties are achieved through the simultaneous presence of a chitosan-derived polysaccharide (α-), advantageously obtained by reacting chitosan with succinic anhydride, a natural or modified polysaccharide (β-), different from the chitosan-derived polysaccharide (α-), and a polyol (β-). The resulting cosmetic composition provides a visible and lasting smoothing of the skin surface with exceptional user comfort.

[0006] The cosmetic composition of the invention also exhibits improved stability and formability properties compared to similar cosmetic compositions based on natural chitosan. This improved formability results in compatibility with a wider range of gelling agents, and in particular with anionic gelling agents.

[0007] General description of the invention

[0008] The present invention relates first to a cosmetic composition comprising a mixture capable of forming an elastic film comprising: a- at least one chitosan-derived polysaccharide comprising amide and carboxylic acid functions, b- at least one natural or modified polysaccharide, different from the chitosan-derived polysaccharide a-, and c- at least one polyol.

[0009] In the following description, the term "cosmetic composition" refers both to the cosmetic composition according to the invention and to the cosmetic composition used in the process of the invention.

[0010] In the description, we speak interchangeably of elastic mixture or of mixture capable of forming an elastic film.

[0011] A polymer is said to be film-forming within the meaning of the invention if, after evaporation of the volatile substances present in the medium, a continuous and homogeneous film is observed to form. Intermolecular bonds, responsible for the mechanical properties, then form between the polymer chains and with other components such as plasticizers to create a film that does not penetrate the skin and provides resistance to water and sebum, non-transfer, etc.

[0012] The elastic blend of the cosmetic composition of the invention comprises a chitosan α-derived polysaccharide, also called a contractile film-forming polymer, which provides an immediate smoothing / tightening (lifting) effect. This contractile effect occurs upon drying, as hydrogen bonds form between the polymer chains to create contraction.

[0013] The chitosan-derived polysaccharide of the invention comprises amide and carboxylic acid groups. In a preferred embodiment, the amide groups of the chitosan-derived polysaccharide bear carboxylic acid groups. More particularly, it may be a chitosan in which the chitosan amine groups are replaced by amide groups bearing carboxylic acid groups. The chitosan-derived polysaccharide of the invention is advantageously obtained from chitosan having a molecular weight ranging from 10,000 g·mol⁻¹ to 30,000 g·mol⁻¹, and preferably from 15,000 g·mol⁻¹ to 25,000 g·mol⁻¹. The chitosan from which the chitosan-derived polysaccharide is obtained is obtained by partial or total deacetylation of chitin.

[0014] In an advantageous embodiment of the invention, the chitosan-derived polysaccharide is obtained by reacting chitosan with succinic anhydride.

[0015] In a particularly advantageous embodiment of the invention, the chitosan-derived polysaccharide is CHITOSAN SUCCINAMIDE (INCI name).

[0016] In one embodiment, the cosmetic composition of the invention comprises from 0.1 to 10%, preferably from 0.5 to 5%, and more preferably from 0.8 to 2%, by weight of chitosan-derived polysaccharide a- relative to the total weight of said cosmetic composition.

[0017] The elastic mixture of the cosmetic composition of the invention also comprises a natural or modified β-polysaccharide, distinct from the chitosan-derived α-polysaccharide, also called an elastic film-forming polymer, which provides an elastic (comfortable) effect to the composition. The natural or modified β-polysaccharide of the invention has the advantage of providing, in mixture with the other ingredients A dry, elastic film that is transparent and remains transparent after undergoing mechanical deformation (stretching). In particular, the film formed on the skin retains its transparency under multiple mechanical stresses, so that it does not, over time, alter the color of the cosmetic composition deposited on the skin into which the mixture has been introduced.

[0018] The natural or modified b- polysaccharide of the invention, different from the chitosan-derived a- polysaccharide, is selected from pullulan, a modified chitosan, a modified starch, and mixtures thereof.

[0019] In one embodiment, the natural or modified β- polysaccharide of the invention, distinct from the chitosan-derived α- polysaccharide, is pullulan (INCI name: PULLULAN). Pullulan is a water-soluble exopolysaccharide produced by the fungus Aureobasidium pullulans. It is a polysaccharide composed of maltotriose units, also known as α-1,4-;α,6-glucan. The three glucose units that make up the maltotriose are linked by α-1,4- glycosidic bonds, while the maltotriose units are linked together by α-1,6- glycosidic bonds.

[0020] In another embodiment, the natural or modified b- polysaccharide of the invention is a modified chitosan, different from the chitosan-derived polysaccharide a-, preferably selected from an alkylated chitosan, a hydroxyalkylated chitosan, an acetylated chitosan, a chitosan hydrolysate, a phosphated chitosan, and mixtures thereof, more preferably a hydroxyalkylated chitosan, and even more preferably a hydroxypropyl chitosan (INCI name: HYDROXYPROPYL CHITOSAN).

[0021] In another embodiment, the natural or modified β- polysaccharide of the invention, distinct from the chitosan-derived α- polysaccharide, is a modified starch. The modified starches of the invention are obtained from native starches that have been modified chemically and / or physically and / or enzymatically to improve their elastic properties. The native starches can be derived from a wide variety of sources, such as, for example, starches from maize, wheat, rice, buckwheat, barley, oats, millet, rye, sorghum, cassava, potato, sweet potato, tapioca, banana, plantain, malanga, taro, chestnut, beans, peas, and preferably native starches from maize, wheat, rice, cassava, potato, tapioca, and peas.

[0022] When the natural or modified β- polysaccharide of the invention, different from the chitosan-derived α- polysaccharide, is a modified starch, it advantageously has a weight-average molecular weight greater than 10⁶ g.mol⁻¹, and preferably from 10⁶ to 10⁹ g.mol⁻¹. The weight-average molecular weight can be determined by HPSEC-MALLS (high-performance size-exclusion chromatography). performance coupled online with multi-angle laser light scattering detection).

[0023] When the natural or modified b- polysaccharide of the invention, different from the chitosan-derived a- polysaccharide, is a modified starch, it may advantageously be selected from an alkylated starch, a hydroxyalkylated starch, an acetylated starch, a starch hydrolysate, an oxidized starch, a phosphated starch, a hydroxyalkylated, phosphated, or acetylated distarch phosphate, and mixtures thereof. Preferred modified starches are hydroxyalkylated starches, and more particularly hydroxypropyl starch (INCI name: HYDROXYPROPYL STARCH), such as the Beauté By Roquette® ST 720 and ST 730 products marketed by the ROQUETTE company.

[0024] The natural or modified b- polysaccharide preferably represents 0.1 to 10%, preferably 0.5 to 5%, and more preferably 1 to 3%, by weight relative to the total weight of the cosmetic composition.

[0025] The elastic blend of the cosmetic composition of the invention also comprises a c-polyol, which aids in the dispersion and plasticizes the polymers present in the cosmetic composition. Thus, the c-polyol acts as a plasticizer by providing mobility between the polymer chains, making them more elastic and flexible, and providing an improved smoothing effect combined with better durability.

[0026] The c-polyol of the invention may be an alcohol having from 1 to 30 carbon atoms and 2 to 12 hydroxyl groups. The c-polyol may also be a sugar such as glucose, sorbitol, or mannitol. Advantageously, the c-polyol has a weight-average molecular weight ranging from 300 to 800 g / mol.

[0027] The c- polyol is advantageously selected from among diols, polyglycerols of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 1 to 10, and their mixtures.

[0028] In one embodiment, the c- polyol is a diol selected from aliphatic or aromatic, linear or branched C2-Ci2 diols, preferably selected from propane-1,2-diol, propane-1,3-diol, butane-1,2-diol, butane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, octane-1,8-diol, and mixtures thereof, more preferably propane-1,3-diol, butane-1,2-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, octane-1,8-diol, and mixtures thereof.

[0029] In another embodiment, the c- polyol is a polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 1 to 10.

[0030] In a particularly advantageous embodiment, the c- polyol is a polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n = 1, 3, 6 or 10. More specifically, this refers to the polyglycerol with the formula H-(O-CH2-CH(OH)-CH2)n-OH, where n = 3 (INCI name: POLYGLYCERIN-3), marketed by SAKAMOTO YAKUHIN KOGYO under the reference PGL-S MB, or the polyglycerol with the formula H-(O-CH2-CH(OH)-CH2)n-OH, where n = 6 (INCI name: POLYGLYCERIN-6), marketed by SAKAMOTO YAKUHIN KOGYO under the reference POLYGLYCERIN 500 MB. Compared to other polyols, POLYGLYCERIN-3 is more advantageous because it allows for a better level of plasticization of the chitosan-derived polysaccharide α- and the natural or modified polysaccharide β- on the skin surface.

[0031] The c- polyol preferably represents 0.1 to 15%, preferably 0.5 to 10%, and more preferably 1 to 5%, by weight relative to the total weight of the cosmetic composition.

[0032] In one embodiment, the cosmetic composition of the invention comprises: a- from 0.1 to 10%, preferably from 0.5 to 5%, and more preferably from 0.8 to 2%, by weight of chitosan-derived polysaccharide a-, b- from 0.1 to 10%, preferably from 0.5 to 5%, and more preferably from 1 to 3%, by weight of natural or modified polysaccharide b-, and c- from 0.1 to 15%, preferably from 0.5 to 10%, and more preferably from 1 to 5%, by weight of c- polyol, relative to the total weight of the cosmetic composition.

[0033] The quantities of each of the constituents a-, b-, and c- are preferably chosen so that the cosmetic composition provides a pleasant feel without being too sticky, while ensuring good adhesion to the skin. Thus, the proportions of each of the constituents a-, b-, and c- are adjusted to satisfy the desired compromise between stickiness and adhesion properties. Depending on the formula, for example, if it is a foundation or a serum, a compromise will be sought between adherence to the skin and the viscoelasticity of the composition. For example, if the formula contains powders, the quantity of polyol to be introduced will be greater in order to maintain a certain plasticity and elasticity.

[0034] The mass ratio between the polyol c- and the two polysaccharides a- and b- is preferably between 20 / 80 and 80 / 20, and preferably between 30 / 70 and 70 / 30.

[0035] According to a particularly advantageous embodiment, the cosmetic composition of the invention comprises a mixture capable of forming an elastic film comprising: a- at least one polysaccharide selected from CHITOSAN SUCCINAMIDE, b- at least one modified polysaccharide selected from PULLULAN, HYDROXYPROPYL STARCH, and HYDROXYPROPYL CHITOSAN, and c- at least one polyol selected from polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n = 1, 3, 6 or 10, advantageously in the preferred % by weight indicated above.

[0036] In an advantageous embodiment, the cosmetic composition of the invention contains from 0.5 to 25%, preferably from 1 to 15%, and more preferably from 1 to 10%, by weight relative to the total weight of the cosmetic composition, of a mixture capable of forming an elastic film consisting of chitosan-derived polysaccharide a-, natural or modified polysaccharide b-, and polyol c-, as defined above.

[0037] The cosmetic composition of the invention may also include an aqueous phase, which may include water. Preferably, the composition comprises 40 to 99%, more preferably 50 to 90%, and more preferably 60 to 80%, by weight of water relative to the total weight of the cosmetic composition. In the case of an oil-in-water emulsion, the amount of water preferably varies from 50 to 80% by weight relative to the total weight of the cosmetic composition. In the case of a water-in-oil emulsion, the amount of water preferably varies from 15 to 60% by weight relative to the total weight of the cosmetic composition. In the case of an aqueous dispersion, the amount of water represents at least 60%, and preferably at least 70% by weight relative to the total weight of the cosmetic composition.

[0038] According to one embodiment of the invention, the cosmetic composition may further comprise at least one cosmetic active ingredient. The cosmetic active ingredient may, in particular, advantageously be chosen from among a moisturizing agent, an anti-wrinkle agent, an antioxidant, a free radical scavenging agent, an agent that repairs the destructive effects of ultraviolet rays, or a slimming agent such as caffeine. Preferably, the cosmetic active ingredient is chosen from among hyaluronic acids, such as sodium hyaluronate. The invention thus relates, according to one of its aspects, to a cosmetic composition containing water and at least one cosmetic active ingredient in a proportion ranging from 0.01 to 5% by weight, relative to the total weight of the cosmetic composition.

[0039] The cosmetic composition of the invention may further comprise a hydrophilic gelling agent. Advantageously, natural or synthetic polysaccharides, other than the chitosan-derived polysaccharide a- and the natural or modified polysaccharide b- of the invention, may be used as hydrophilic gelling agents, and preferably chosen from among carbomers (such as Carbopol® Ultrez), xanthan gum (such as Rhodicare® XC or T marketed by Solvay Novecare or Keltrol® CG LAXT marketed by CP Keltro), agar-agar (such as Ina Agar CS 83 marketed by Iwase Cosfa), gellan gum (such as Kelcogel® CG-LA marketed by Azelis), carrageenans (such as Satiagum™ VPC 430 marketed by Cargill Beauty), cellulose and its derivatives such as hydroxyethylcellulose (such as Klucel® GF and Natrosol® 250 HHX, marketed by Ashland) and hydroxypropylcellulose, corn starch, cellulose carboxymethyl ethers (such as Blanose™ 7H3SF, marketed by Ashland), bis-decyltetradeceth-20 ether-based copolymers (such as Adeka Nol GT-700, marketed by Adeka), Sclerotium gum (INCI name: SCLEROTIUM GUM) (such as Amigel®, marketed by Alban Muller International (Croda)), and mixtures thereof. Synthetic polymers such as ammonium acryloyldimethyltaurate / VP copolymer (Aristoflex® AVC, marketed by Clariant International Ltd.), and their derivatives, may also be advantageously mentioned.Particularly advantageously, the gelling agent is chosen from xanthan gum (such as Rhodicare® XC or T marketed by Solvay Novecare or Keltrol® CG LAXT sold by CP Keltro), gellan gum (such as Kelcogel® CG-LA marketed by Azelis), hydroxyethylcellulose (such as Klucel® GF and Natrosol® 250 HHX marketed by Ashland), Sclerotium gum (INCI name: SCLEROTIUM GUM) (such as Amigel® marketed by Alban Muller International (Croda)), ammonium acryloyldimethyltaurate / VP copolymer (Aristoflex® AVC marketed by Clariant International Ltd.), and mixtures thereof.

[0040] The cosmetic composition of the invention may further comprise at least one pH adjusting agent. This pH adjusting agent is advantageously chosen from alkali hydroxides such as sodium hydroxide or ammonium hydroxide, triethanolamine, 2-amino-2-(hydroxymethyl)-1,3-propanediol, borates, phosphates, pyrophosphates, ascorbic acid, and its salts, such as trisodium citrate dihydrate, sorbic acid and its salts, phosphoric acid and its salts, citric acid and its salts, lactic acid and its salts, boric acid and its salts, acetic acid and its salts, preferably alkali hydroxides, and more preferably an alkali hydroxide such as sodium hydroxide. The pH adjusting agent is advantageously used in an amount capable of giving the cosmetic composition a pH ranging from 4 to 7.According to one embodiment, the pH adjusting agent is present in an amount ranging from 0.01 to 1% by weight relative to the total weight of the cosmetic composition.

[0041] The cosmetic composition of the invention may further include one or more cosmetic excipients such as opacifying agents, perfumes, reflective agents, coalescing agents, preservatives such as chlorphenesin (INCI name: CHLORPHENESIN), UVA and UVB ultraviolet protection agents, in particular filters, organic pigments and nanopigments, such as zinc, iron and titanium oxides.

[0042] The cosmetic composition of the invention may be in the form of a gelled or non-gelled aqueous composition, a gelled or non-gelled emulsion, of the oil-in-water or water-in-oil type, a cream, a serum, a mask, or a foundation.

[0043] In the case of an oil-in-water emulsion, for example a skincare cream, the elastic mixture of the invention forms the continuous phase of said emulsion.

[0044] In the case of a water-in-oil emulsion, for example a foundation, the elastic mixture of the invention forms the dispersed phase of said emulsion.

[0045] Another object of the invention relates to a method for preparing a cosmetic composition according to the invention, as described above.

[0046] The process for preparing the cosmetic composition of the invention comprises the following steps: (i) preparation of a mixture capable of forming an elastic film by dissolving in water: - at least one chitosan-derived polysaccharide (a-), - at least one natural or modified polysaccharide (b-), and - at least one polyol (c-), and (ii) dispersion of the mixture obtained in step (i) in an aqueous phase possibly including cosmetic active ingredients and / or excipients.

[0047] The chitosan-derived polysaccharide components a-, natural or modified polysaccharide b-, and polyol c-, implemented in the process of preparing the cosmetic composition of the invention are as defined above.

[0048] Advantageously, step (i) is carried out, under stirring, at a temperature ranging from 50 to 120°C, and preferably from 70 to 100°C, for a period ranging from 5 minutes to 1 hour, and preferably for about 30 minutes. The mixture obtained at the end of step (i) is then cooled to room temperature (20°C).

[0049] In step (i), the elastic mixture can be prepared by first dissolving the c- polyol in water. The chitosan-derived polysaccharide a- is then dissolved or dispersed in the water-based c- polyol mixture, possibly with the addition of heat and stirring. Once the chitosan-derived polysaccharide a- has dissolved or dispersed, the natural or modified b- polysaccharide is then added, with heat added to thoroughly homogenize the different components. Advantageously, the chitosan-derived polysaccharide a- and the natural or modified b- polysaccharide are added successively, with stirring, at a temperature ranging from 50 to 120°C, and preferably from 70 to 100°C, for a period ranging from 5 minutes to 1 hour, and preferably for about 30 minutes. The mixture obtained at the end of step (i) is then cooled to room temperature (20°C).

[0050] During step (ü), the mixture prepared during step (i) is added to an aqueous phase comprising cosmetic actives and / or other cosmetic excipients.

[0051] In another embodiment, the cosmetic composition of the invention is prepared by successively adding each of the components chitosan-derived polysaccharide a-, natural or modified polysaccharide b-, and polyol c-, directly into the aqueous phase of the cosmetic composition, without prior mixing. Advantageously, the components chitosan-derived polysaccharide a-, natural or modified polysaccharide b-, and polyol c- are added successively, with stirring, at a temperature ranging from 50 to 120°C, and preferably from 70 to 100°C, for a period ranging from 5 minutes to 1 hour, and preferably for approximately 30 minutes. The mixture obtained at the end of step (i) is then cooled to room temperature (20°C).

[0052] In the particular case of an emulsion, the components chitosan-derived polysaccharide a-, natural or modified polysaccharide b-, and polyol c-, are added to the aqueous dispersing phase before dispersion in the oily phase.

[0053] Finally, a last object of the invention relates to a skin care process comprising a step of applying a cosmetic composition as defined according to the invention, on at least one part of the body and / or face, for a firming and smoothing effect.

[0054] In one embodiment, the application step on at least one part of the body and / or face is carried out on at least one area of ​​skin, in particular of the face and / or décolleté, showing signs of aging or fatigue, such as loss of firmness, loss of elasticity, or sagging skin, to obtain an effect chosen from a smoothing effect, a tightening effect, a skin bouncing effect, or a combination of one of these effects.

[0055] The cosmetic composition, when applied directly to the skin, forms a film after application and gradual evaporation of the water in the composition. This film exhibits elastic mechanical properties and a texture particularly well-suited to makeup application. Furthermore, this type of texture possesses properties that are useful both aesthetically and in terms of user comfort, especially near highly mobile areas such as the eyes and lips. The elastic properties of the cosmetic composition of the invention are particularly useful for application to areas of the body subject to significant movement, such as the skin of the face.

[0056] The skin care process may include the topical application to the affected areas of skin of an effective amount of a cosmetic composition according to the invention as defined above, to obtain a second-skin sensation.

[0057] In addition to the foregoing provisions, the invention also includes other provisions which will become apparent from the following supplementary description, which relates to the preparation of cosmetic compositions according to the invention and comparative cosmetic compositions.

[0058] Examples:

[0059] In the following examples, and unless otherwise indicated, all percentages are given as mass percentages, ingredients are designated by their INCI name, and the temperature is given in degrees Celsius.

[0060] Method for characterizing the smoothing effect in vivo at 1 hour and 4 hours:

[0061] The test consists of evaluating and comparing the smoothing and tightening effect on the corner area of the eye, known as "crow's feet," after 1 hour and 4 hours, on a panel of 3 volunteers. The compositions were applied to the "crow's feet" at the corner of the eye and then left to dry for 15 minutes. Visual observations were made immediately after drying and after 4 hours. All measurements were taken at a temperature of 22°C and 50% relative humidity.

[0062] Evaluation criteria:

[0063] +++ means that the composition has a very significant smoothing / tightening effect on the leg goose,

[0064] ++ means that the composition has a significant smoothing / tightening effect on crow's feet,

[0065] + means that the composition has a moderate smoothing effect, slightly visible on the paw of goose, and

[0066] 0 means that the composition has no smoothing effect.

[0067] Example 1:

[0068] Three compositions according to the invention (compositions 1, 2, 3 and 4) were prepared and compared to a comparative composition free of natural or modified b- polysaccharide (comparative composition 5) corresponding to the following formulas:

[0069] [Tables 1] Ingredients (chemical names or INCI) Phases Quantity (% by weight) Composition 1 according to the invention Composition 2 according to the invention Composition 3 according to the invention Comparative composition 4 Comparative composition 5 PURIFIED WATER EA QSP 100 CHLORPHEN ESIN A 0.3 SODIUM HYD ROXIDE A 0.05 POLYGLYCE RIN-3 (PGL-S) A 10 CHITOSAN S UCCINAMIDE B 4 4 4 - 4 CARBOXYM THYL CHITO SAN B 4 PULLULAN C 6 - - 6 - HYDROXYPR OPYL CHITO SAN C - 6 - - - HYDROXYPR OPYL ST ARC HC - - 6 - -

[0070] The ingredients of phase A were weighed into a beaker and then mixed using a deflocculating turbine in a water bath at 85°C. Phase B was weighed, added to phase A, and mixed for 30 minutes at 600 rpm. Phase C was weighed, added to phase A, and mixed at 600 rpm for 30 minutes. The mixture was removed from the water bath and blended until it reached room temperature.

[0071] The smoothing effect of these four compositions has been characterized. The results obtained are summarized in the following Table 2:

[0072] [Tables2] Immediate smoothing effect (at 15 min) Smoothing effect at 4h Composition 1 of the invention ++ ++ Composition 2 of the invention +++ +++ Composition 3 of the invention +++ +++ Comparative composition 4 + 0 Comparative composition 5 ++ 0

[0073] Compositions 1, 2 and 3 of the invention comprising CHITOSAN SUCCINAMIDE (a chitosan-derived polysaccharide) in combination with a natural or modified polysaccharide and a polyol exhibit a very good smoothing effect immediate and long-term (4 hours). In contrast, comparative composition 4 based on CARBOXYMETHYL CHITOSAN and comparative composition 5, free from natural or modified b- polysaccharide, present an immediate smoothing effect but one that does not last over time.

[0074] Example 2:

[0075] A composition according to the invention (composition A) was prepared and compared to a comparative composition in which the CHITOSAN SUCCINAMIDE was replaced by unmodified chitosan (INCI name: CHITOSAN). These compositions correspond to the following formulas:

[0076] [Tables3] Ingredients (chemical names or INCI) Phases Composition A (in vention) Composition B (comparative) PURIFIED WATER Al QSP 100 POLYGLYCERIN-3 (PGL-S) Al 2 CHLORPHENESIN Al 0.3 SCLEROTIUM GUM A2 0.5 CHITOSAN SUCCINAMIDE A3 0.8 - CHITOSAN A3 - 0.8 PULLULAN A3 1.2 SODIUM HYDROXIDE A4 0.05 PURIFIED WATER A4 0.5 CETEARYL ALCOHOL B 4 STEARETH-21 B 1 GLYCERYL STEARATE B 2 CAPRYLIC / CAPRIC / MYRISTIC / STEA RIC TRIGLYCERIDE B 2 DIMETHICONE B 1 LIMNANTHES ALBA B 3 TRIDECANE B 5 C10-18 TRIGLYCERIDES B 2

[0077] The ingredients of phase A1 were weighed into a beaker and then heated to 75°C. The ingredients of phase A2 were dispersed in phase A1. The ingredients of phase A3 were also added and then homogenized. The ingredients of the Phase B was weighed in a beaker and then heated to 75°C. Phase B was then slowly emulsified in phase A, at 75°C, using an emulsifier at a speed of 800 rpm for 5 minutes, then passed through a deflocculator, and finally cooled to 35°C.

[0078] The stability of compositions A and B was evaluated at T = 0 minutes, then after one month in an oven at 50°C. The results obtained are summarized in the following Table 4:

[0079] [Tables 4] Appearance of the composition at T = 0 minutes. Stability of the formula after 1 month at 50°C. Composition A of the invention: Smooth and glossy formula, fine emulsion. Smooth and glossy formula, fine emulsion. Comparative Composition B: Smooth and glossy formula, no phase separation. Loss of structure, phase separation.

[0080] Example 3:

[0081] An oil-in-water skincare cream according to the invention corresponding to the composition of Table 5 below has been prepared.

[0082] [Tables5] Ingredients (chemical names or INCI) Phases Quantities (% by weight) PURIFIED WATER Al QSP 100 POLYGLYCERIN-3 (PGL-S) Al 2 CHLORPHENESIN Al 0.2 SCLEROTIUM GUM A2 0.5 CHITOSAN SUCCINAMIDE A3 0.8 HYDROXYPROPYL STARCH A3 1.2 CETEARYL ALCOHOL B 4 STEARETH-21 B 1 GLYCERYL STEARATE B 2 CAPRYLIC / CAPRIC / MYRISTIC / STEAR IC TRIGLYCERIDE B 2 DIMETHICONE B 1 LIMNANTHES ALBA B 3 TRIDECANE B 5 C10-18 TRIGLYCERIDES B 2

[0083] The ingredients of phase A1 were weighed into a beaker and then heated to 75°C. The ingredients of phase A2 were dispersed in phase A1. The ingredients of phase A3 were also added and then homogenized. The ingredients of phase B were weighed into a beaker and then heated to 75°C. Phase B was then slowly emulsified in phase A at 75°C using an emulsifier at a speed of 800 rpm for 5 minutes, then passed through a deflocculator, and finally cooled to 35°C.

[0084] The resulting cosmetic composition exhibits an immediate and very significant smoothing / tightening effect at 4 hours.

[0085] Example 4:

[0086] An oil-in-water skincare cream according to the invention corresponding to the composition of Table 6 below has been prepared.

[0087] [Tableauxô] Ingredients (chemical names or INCI) Phases Quantities (% by weight) PURIFIED WATER Al QSP 100 POLYGLYCERIN-3 (PGL-S) Al 2 CHLORPHENESIN Al 0.2 SCLEROTIUM GUM A2 0.5 CHITOSAN SUCCINAMIDE A3 0.8 PULLULAN A3 1.2 CETEARYL ALCOHOL B 4 STEARETH-21 B 1 GLYCERYL STEARATE B 2 CAPRYLIC / CAPRIC / MYRISTIC / STEARIC TRIGLYCERIDE B 2 DIMETHICONE B 1 LIMNANTHES ALBA B 3 TRIDECANE B 5 C10-18 TRIGLYCERIDES B 2

[0088] The ingredients of phase A1 were weighed into a beaker and then heated to 75°C. The ingredients of phase A2 were dispersed in phase A1. The ingredients of phase A3 were also added and then homogenized. The ingredients of phase B were weighed into a beaker and then heated to 75°C. Phase B was then slowly emulsified in phase A, at 75°C, using an emulsifier at a speed of 800 rpm for 5 minutes, then passed through a deflocculator, and finally cooled to 35°C.

[0089] The resulting cosmetic composition exhibits an immediate and very significant smoothing / tightening effect at 4 hours.

[0090] Example 5:

[0091] An oil-in-water skincare cream according to the invention corresponding to the composition of Table 7 below has been prepared.

[0092] [Tables7] Ingredients (chemical names or INCI) Phases Quantities (% by weight) PURIFIED WATER Al QSP 100 POLYGLYCERIN-3 (PGL-S) Al 2 CHLORPHENESIN Al 0.2 SCLEROTIUM GUM A2 0.5 CHITOSAN SUCCINAMIDE A3 0.8 HYDROXYPROPYL CHITOSAN A3 1.2 CETEARYL ALCOHOL B 4 STEARETH-21 B 1 GLYCERYL STEARATE B 2 CAPRYLIC / CAPRIC / MYRISTIC / STEARI C TRIGLYCERIDE B 2 DIMETHICONE B 1 LIMNANTHES ALBA B 3 TRIDECANE B 5 C10-18 TRIGLYCERIDES B 2

[0093] The ingredients of phase A1 were weighed into a beaker and then heated to 75°C. The ingredients of phase A2 were dispersed in phase A1. The ingredients of phase A3 were also added and then homogenized. The ingredients of phase B were weighed into a beaker and then heated to 75°C. Phase B was then slowly emulsified in phase A at 75°C using an emulsifier at a speed of 800 rpm for 5 minutes, then passed through a deflocculator, and finally cooled to 35°C.

[0094] The resulting cosmetic composition exhibits an immediate and very significant smoothing / tightening effect at 4 hours.

Claims

Demands

1. Cosmetic composition characterized in that it comprises a mixture capable of forming an elastic film comprising: a- at least one chitosan-derived polysaccharide comprising amide and carboxylic acid functions, b- at least one natural or modified polysaccharide, different from the chitosan-derived polysaccharide a-, and c- at least one polyol.

2. Cosmetic composition according to claim 1, wherein the amide functions of the chitosan-derived polysaccharide a- bear carboxylic acid functions.

3. A cosmetic composition according to claim 1 or claim 2, wherein the chitosan-derived polysaccharide is obtained from chitosan having a molecular weight ranging from 10,000 g.mof1 to 30,000 g.mof1, and preferably from 15,000 g.mof1 to 25,000 g.mof1

4. Cosmetic composition according to any one of claims 1 to 3, wherein the chitosan-derived polysaccharide α- is obtained by reaction of chitosan with succinic anhydride.

5. Cosmetic composition according to any one of claims 1 to 4, wherein the chitosan-derived polysaccharide α- is CHITOSAN SUCCINAMIDE.

6. Cosmetic composition according to any one of claims 1 to 5, wherein the b- polysaccharide is selected from pullulan, a modified chitosan, a modified starch, and mixtures thereof.

7. Cosmetic composition according to claim 6, wherein the polysaccharide b- is pullulan.

8. Cosmetic composition according to claim 6, wherein the polysaccharide b- is a modified chitosan different from the polysaccharide derived from chitosan a-, said polysaccharide b- being preferably selected from an alkylated chitosan, a hydroxyalkylated chitosan, an acetylated chitosan, a chitosan hydrolysate, a phosphated chitosan, and mixtures thereof, more preferably a hydroxyalkylated chitosan, and even more preferably a hydroxypropyl chitosan (HYDROXYPROPYL CHITOSAN).

9. A cosmetic composition according to claim 6, wherein the polysaccharide b- is a modified starch, preferably selected among an alkylated starch, a hydroxyalkylated starch, an acetylated starch, a starch hydrolysate, an oxidized starch, a phosphated starch, a hydroxyalkylated, phosphated or acetylated distarch phosphate, and mixtures thereof, more preferably a hydroxyalkylated starch, and even more preferably hydroxypropyl starch (HYDROXYPROPYL STARCH).

10. Cosmetic composition according to any one of claims 1 to 9, wherein the c- polyol is selected from diols, polyglycerols of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 1 to 10, and mixtures thereof.

11. Composition according to any one of claims 1 to 10, wherein the c- polyol is a linear or branched aliphatic or aromatic C2-Cl2 diol, preferably selected from propane-1,2-diol, propane-1,3-diol, butane-1,2-diol, butane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, octane-1,8-diol, and mixtures thereof, more preferably propane-1,3-diol, butane-1,2-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, octane-1,8-diol, and mixtures thereof.

12. Cosmetic composition according to any one of claims 1 to 11, wherein the polyol c- is a polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 1 to 10, said polyol c- preferably being a polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n = 1, 3, 6 or 10.

13. Cosmetic composition according to any one of claims 1 to 12, characterized in that it comprises from 0.1 to 10%, preferably from 0.5 to 5%, and more preferably from 0.8 to 2%, by weight of chitosan-derived polysaccharide α- relative to the total weight of the cosmetic composition.

14. Cosmetic composition according to any one of claims 1 to 13, characterized in that it comprises from 0.1 to 10%, preferably from 0.5 to 5%, and more preferably from 1 to 3%, by weight of natural or modified b- polysaccharide relative to the total weight of the cosmetic composition.

15. Cosmetic composition according to any one of claims 1 to 14, characterized in that it comprises from 0.1 to 15%, preferably from 0.5 to 10%, and more preferably from 1 to 5%, by weight of c-polyol relative to the total weight of the cosmetic composition.

16. Composition according to any one of claims 1 to 15, wherein the weight ratio of polyol c- / (chitosan-derived polysaccharide a- + natural or modified polysaccharide b-) varies from 20 / 80 to 80 / 20, and preferably from 30 / 70 to 70 / 30.

17. Composition according to any one of claims 1 to 16, wherein the mixture of chitosan-derived polysaccharide a-, natural or modified polysaccharide b-, and polyol c-, represents from 0.5 to 25%, preferably from 1 to 15%, and more preferably from 1 to 10%, by weight relative to the total weight of the cosmetic composition.

18. Composition according to any one of claims 1 to 17, characterized in that it further comprises at least one cosmetic active ingredient, preferably selected from a moisturizing agent, an anti-wrinkle agent, an antioxidant agent, an anti-radical agent, an agent for repairing the destructive effects of ultraviolet rays, or a slimming agent, and more preferably a cosmetic active ingredient selected from hyaluronic acids.

19. Composition according to any one of claims 1 to 18, characterized in that it is in the form of a gelled or non-gelled aqueous composition, a gelled or non-gelled emulsion, of the oil-in-water or water-in-oil type, a cream, a serum, a mask, or a foundation.

20. A method for preparing a cosmetic composition according to any one of claims 1 to 19, characterized in that it comprises the following steps: (i) preparation of a mixture capable of forming a film by dissolving in water: - at least one chitosan-derived polysaccharide a-, - at least one natural or modified polysaccharide b-, and - at least one polyol c-, and (ii) dispersion of the mixture obtained in step (i) in an aqueous phase optionally comprising cosmetic actives and / or excipients.

21. A skin care method, characterized in that it comprises a step of applying a composition as defined according to any one of claims 1 to 19, to at least one part of the body and / or face.

22. A method according to claim 21, wherein the application step on at least one part of the body and / or face is carried out on less an area of ​​skin, particularly on the face and / or décolleté, showing signs of aging or fatigue, such as loss of firmness, loss of elasticity, or sagging skin, to obtain an effect chosen from a smoothing effect, a tightening effect, a skin-bouncing effect, or a combination of these effects.