Cosmetic composition comprising an elastic mixture on the basis of chitosan, pullulan and polyglycerol

Abstract

The invention relates to an elastic mixture which comprises a chitosan or one of the salts thereof, a pullulan or one of the salts thereof, and a polyglycerol, and which has a tightening effect and deforms elastically in order to follow the movements and mechanical deformations of the surface of the skin. The present invention also relates to a cosmetic composition containing an elastic mixture according to the invention, a method of preparing a cosmetic composition according to the invention, and a skin care method comprising a step of applying a cosmetic composition according to the invention to the skin.

Description

[0001] Description

[0002] Title of the invention: Cosmetic composition comprising an elastic mixture based on chitosan, pullulan and polyglycerol

[0003] Technical Field

[0004] The present invention relates to the cosmetic field, and more particularly to an elastic mixture and a cosmetic composition comprising an elastic mixture according to the invention, which provide a tightening effect and deform elastically to follow the movements and mechanical deformations of the surface of the skin. The present invention also relates to a process for preparing an elastic mixture and a cosmetic composition according to the invention, as well as a skin care process comprising a step of applying a cosmetic composition according to the invention to the skin.

[0005] Communication on anti-wrinkle effects with immediate and lasting skin smoothing is a key asset and a strong driver of innovation and satisfaction for consumers. Currently, the immediate anti-wrinkle smoothing effect is supported, essentially, by the incorporation of contractile film-forming polymers, known for their tightening effect. However, the effectiveness of these polymers is very limited, either by their durability over time (the polymer film cracks) and lack of comfort, or by a smoothing effect that is not very effective (comfort paradox / tightening effect not achieved). On the other hand, to date, the smoothing effect provided by tightening polymers is insufficient compared to consumer expectations and is not sustainable at sensory-acceptable doses.

[0006] The Applicant has already described in application WO 2013 / 167835 a cosmetic treatment providing a tightening and smoothing effect comprising a specific elastic complex consisting of at least one gelling or thickening starch, at least one polyol and at least one polymer chosen from polyvinyl alcohols, vinylpyrrolidone polymers and copolymers and latexes. These compositions, however, have the disadvantage of being too sticky; they also lack adhesion to the skin (peelability problem). The inventors have now developed a mixture of specific compounds capable of forming an elastic film having an immediate, visible and lasting smoothing effect. The solution proposed by the inventors consists of combining a tightening polymer (highly contractile but rigid) with a polymer having good elastic properties obtained through optimized plasticization (selection of glycols).The film thus formed can deform reversibly, so that it resumes after deformation, for example after stretching, the state it had before the application of the mechanical stress provided, for example by a deformation of the skin. The film formed by said mixture has a greater resistance to breakage, which makes it possible to maintain intact the mechanical properties of the film formed on the surface of the skin. Once incorporated into a cosmetic composition, the elastic mixture of the invention has an improved combined tensing and elastic effect, capable of following the movements of the skin without cracking. The effect obtained is comparable to a sheathing effect, the elastic mixture of the invention providing elasticity to the skin naturally stressed by deformations, such as changes in facial expression or contact with the hands or clothing.The inventors have thus succeeded in cracking the paradox of tensor (wrinkle smoothing by contraction of the polymer film on the skin surface) / elasticity (for comfort and durability of the effect), and in developing a cosmetic mixture capable of combining performances that are difficult to combine, namely a tensor effect combined with an elastic effect, which resolves the tensor / elasticity paradox. The cosmetic compositions comprising the elastic mixture of the invention are capable of acting effectively to achieve smoothing of the skin surface, in particular obtaining a partial or total erasure of wrinkles, including medium and deep wrinkles.

[0007] The elastic mixture of the invention has remarkable properties of tensor and elastic effect on the skin, properties which are linked to the combination of polymers selected for their contraction properties with elastic polymers (elastic properties optimized by the association with a selection of glycol-type plasticizers). The cosmetic compositions comprising the elastic mixture of the invention allow visible and lasting smoothing of the skin surface with very high comfort of use. General description of the invention

[0008] The present invention relates firstly to an elastic or skin-tightening mixture comprising: a- at least one polysaccharide selected from chitosan, its salts, and mixtures thereof, b- at least one polysaccharide, different from polysaccharide a-, selected from pullulan, its salts, and mixtures thereof, and c- at least one polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 2 to 10, and d- water.

[0009] In the following description, we refer indifferently to “elastic mixture” or “mixture capable of forming an elastic film” or “mixture with a skin-tightening effect”.

[0010] A polymer is said to be film-forming within the meaning of the invention if, after evaporation of the volatile materials present in the medium, the formation of a continuous and homogeneous film is observed. Intermolecular bonds, responsible for the mechanical properties, are then formed 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.

[0011] The elastic blend of the invention comprises an α-polysaccharide, also called a contractile film-forming polymer, which provides an immediate smoothing / tightening (lifting) effect. This contractile effect occurs upon drying, with hydrogen bonds forming between the polymer chains to create a contraction.

[0012] The polysaccharide a- of the invention is advantageously an unmodified chitosan. The chitosans that can be used in the context of the invention may be fully or partially deacetylated chitins. The molecular mass of the chitosan used may vary from 20,000 to approximately 5,000,000 g. mol 1 , preferably from 100,000 to 700,000 g. mol 1 . The degree of deacetylation of the chitosan may preferably vary from 50 to 99%. The unmodified chitosan of the invention is advantageously selected from chitosan of natural origin, in particular of fungal or crustacean origin, for example from crabs, lobsters, squid or shrimp. In a particularly preferred embodiment, the polysaccharide a- is fungal chitosan. The fungal chitosan may be marketed, for example, under the name CHITOSAN FUNGAL.

[0013] The elastic mixture of the invention also comprises a b- polysaccharide selected from pullulan, its salts, and mixtures thereof, also called elastic film-forming polymer, which provides an elastic effect (comfort) to the mixture. The b- polysaccharide of the invention has the advantage of providing, when mixed with the other ingredients of the elastic mixture, an elastic dry film which is transparent, and which remains transparent after having undergone mechanical deformations (stretching). In particular, the film formed on the skin retains its transparency under the effect of multiple mechanical stresses, so that it does not disturb over time the color of the deposit on the skin of the cosmetic composition into which the elastic mixture of the invention has been introduced.

[0014] Pullulan is a water-soluble exopolysaccharide produced by the fungus Aureobasidium pullulans. It is a polysaccharide composed of maltotriose units, also known as ol,4-; ol,6-glucan. The three glucose units that make up maltotriose are linked by an ol,4- type sugar bond, while the maltotrioses are connected to each other by o- 1,6- type sugar bonds.

[0015] The elastic mixture of the invention also comprises a c-polyglycerol, which aids in the dispersion and plasticizes the polymers present in the elastic mixture. Thus, the c-polyglycerol 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.

[0016] Polyglycerol c- is a polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 2 to 10, and preferably from 2 to 6. According to a particularly advantageous embodiment, polyglycerol c- is a polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n = 3 and / or 6 (POLYGLYCERIN-3 (PGL-S) and / or POLYGLYCERIN-6 (POLYGLYCERIN 500), marketed for example by the company SAKAMOTO YAKUHIN KOGYO. More particularly, it is the polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n = 3 (POLYGLYCERIN-3), marketed by the company SAKAMOTO YAKUHIN KOGYO under the reference PGL-S. Compared to other polyols, POLYGLYCERIN-3 and / or POLYGLYCERIN-6 allow a better level of plasticization of a- and b- polysaccharides on the surface of the skin.

[0017] According to one embodiment, the elastic mixture of the invention comprises from 0.1 to 15%, preferably from 0.2 to 10%, and more preferably from 0.5 to 7%, by weight of polysaccharide a- relative to the total weight of said elastic mixture.

[0018] According to one embodiment, the elastic mixture of the invention comprises from 0.1 to 10%, preferably from 0.5 to 8%, and more preferably from 1 to 5%, by weight of polysaccharide b- relative to the total weight of said elastic mixture.

[0019] According to one embodiment, the elastic mixture of the invention comprises from 0.1 to 20%, preferably from 0.5 to 15%, and more preferably from 1 to 10%, by weight of polyglycerol c- relative to the total weight of said elastic mixture.

[0020] According to one embodiment, the elastic mixture of the invention comprises from 60 to 99%, preferably from 65 to 98%, and more preferably from 70 to 95%, by weight of water d- relative to the total weight of said elastic mixture.

[0021] According to a particularly advantageous embodiment, the elastic mixture of the invention comprises: a- at least one polysaccharide selected from chitosan (CHITOSAN), b- at least one polysaccharide selected from pullulan (PULLULAN), c- at least one polyglycerol selected from the polyglycerol of formula H-(O-CH2- CH(OH)-CH2) n -OH in which n = 3 and / or 6 (POLYGLYCERIN-3 and / or POLYGLYCERIN-6), and d- water, advantageously in the weight % indicated above. The weight ratio [polysaccharide a- / polysaccharide b-] within the elastic mixture advantageously varies from 1 / 4 to 4 / 1, and more advantageously from 1 / 3 to 2 / 1.

[0022] The weight ratio [(polysaccharide a- + polysaccharide b-) / polyglycerol c-] within the elastic mixture advantageously varies from 1 / 3 to 3 / 1, and more advantageously from 1 / 2 to 2 / 1.

[0023] According to one embodiment, the elastic mixture of the invention may further comprise one or more cosmetic excipients such as preservatives such as chlorphenesin and glycols of the pentylene glycol type, or pH adjusting agents such as alkali hydroxides (sodium hydroxide or ammonium hydroxide, for example). When present, the pH adjusting agent is advantageously used in an amount giving the cosmetic composition a pH ranging from 4.0 to 6.0, and preferably from 5.0 to 6.0.

[0024] A second subject of the invention relates to a cosmetic composition comprising an elastic mixture as defined according to the invention. Thus, the elastic mixture of the invention can be used as such, as an ingredient of a cosmetic composition.

[0025] The quantity of elastic mixture introduced into the cosmetic composition of the invention is advantageously chosen according to the desired cosmetic effect and the desired viscosity. Indeed, the viscosity of the product must be compatible with regular, pleasant and sufficient application to the skin. The quantity of elastic mixture to be integrated into the cosmetic composition is chosen in particular to allow the formation of an elastic film at the time of application of the cosmetic composition to the skin.

[0026] In an advantageous embodiment, the cosmetic composition of the invention contains from 10 to 100%, preferably from 15 to 95%, and more preferably from 15 to 90%, by weight relative to the total weight of the cosmetic composition, of the elastic mixture of the invention consisting of polysaccharide a-, polysaccharide b-, polyglycerol c-, and water d-, ​​as defined above. In an advantageous embodiment, the cosmetic composition of the invention contains from 0.5 to 30%, preferably from 1 to 25%, and more preferably from 2 to 25%, by weight of polysaccharide a-, polysaccharide b- and polyglycerol c-, as defined above, relative to the total weight of the cosmetic composition. The mixture of polysaccharide a-, polysaccharide b- and polyglycerol c-, as defined above, is also called a mixture of active ingredients.

[0027] According to one embodiment, the cosmetic composition of the invention comprises from 0.1 to 15%, preferably from 0.2 to 10%, and more preferably from 0.5 to 5%, by weight of polysaccharide a- relative to the total weight of said cosmetic composition.

[0028] According to one embodiment, the cosmetic composition of the invention comprises

[0029] 0.1 to 10%, preferably 0.5 to 5%, and more preferably 1 to 5%, by weight of polysaccharide b- relative to the total weight of the cosmetic composition.

[0030] According to one embodiment, the cosmetic composition of the invention comprises

[0031] 0.1 to 20%, preferably 0.5 to 15%, and more preferably 1 to 5%, by weight of polyglycerol c- relative to the total weight of the cosmetic composition.

[0032] According to one embodiment, the cosmetic composition of the invention comprises from 15 to 99%, preferably from 15 to 90%, and more preferably from 15 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 40 to 60% 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.

[0033] In one embodiment, the cosmetic composition of the invention comprises: a- from 0.1 to 15%, preferably from 0.2 to 10%, and more preferably from 0.5 to 5%, by weight of polysaccharide a- selected from chitosan, its salts, and mixtures thereof, b- from 0.1 to 10%, preferably from 0.5 to 5%, and more preferably from 1 to 5%, by weight of polysaccharide b- selected from pullulan, its salts, and mixtures thereof, and c- from 0.1 to 20%, preferably from 0.5 to 15%, and more preferably from 1 to 5%, by weight of polyglycerol c- of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 2 to 10, relative to the total weight of the cosmetic composition.

[0034] The quantities of each of the components a-, b- and c- are preferably chosen so that the cosmetic composition provides a pleasant sensation to the touch, without being too sticky, while ensuring good adhesion to the skin. Thus, the proportions of each of the components a-, b- and c- are adjusted to satisfy the desired compromise between stickiness and adhesion properties. Depending on the formulas, for example if it is a makeup composition, such as a foundation, or a skincare composition, such as a cream or a serum, a compromise will be sought between adhesion to the skin and the viscoelasticity of the composition. For example, if the formula contains powders, the quantity of polyglycerol c- to be introduced will be greater in order to maintain a certain plasticity and elasticity of the formula.

[0035] According to a particularly advantageous embodiment, the cosmetic composition of the invention comprises an elastic mixture according to the invention based on: a- at least one polysaccharide selected from chitosan (CHITOSAN), b- at least one polysaccharide selected from pullulan (PULLULAN), c- at least one polyglycerol selected from the polyglycerol of formula H-(O-CH2- CH(OH)-CH2) n -OH in which n = 3 and / or 6 (POLYGLYCERIN-3 and / or POLYGLYCERIN-6), d- water, advantageously in the % by weight indicated previously.

[0036] According to one embodiment, the cosmetic composition of the invention may further comprise at least one cosmetic active ingredient. The cosmetic active ingredient may in particular be advantageously chosen from a moisturizing agent, an anti-wrinkle agent, an antioxidant agent, an anti-free radical agent, an agent for repairing the destructive effects of ultraviolet rays, or a slimming agent such as caffeine. Preferably, the cosmetic active ingredient is chosen from hyaluronic acids, such as sodium hyaluronate. In one of its aspects, the cosmetic composition of the invention may contain 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.

[0037] According to one embodiment, the cosmetic composition of the invention may further comprise at least one gelling agent for the aqueous phase of the composition, preferably chosen from hydrophilic gelling agents capable of gelling the aqueous phase. In the case where the cosmetic composition of the invention also comprises a fatty phase, for example an oily phase, the cosmetic composition of the invention may also comprise at least one gelling agent for the fatty phase of the composition, preferably chosen from lipophilic gelling agents capable of gelling the fatty phase.

[0038] According to one embodiment, 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. When present, the pH adjusting agent is advantageously used in an amount giving the cosmetic composition a pH ranging from 4.0 to 7.0, and preferably from 4.0 to 6.5.

[0039] According to one embodiment, the cosmetic composition of the invention may further comprise one or more cosmetic excipients such as opacifying agents, perfumes, reflective agents, coalescing agents, preservatives such as chlorphenesin (INCI name: CHLORPHENESIN) and glycols of the pentylene glycol type, protective agents against UVA and UVB ultraviolet rays, in particular filters, organic and / or inorganic pigments, such as zinc, iron and titanium oxides.

[0040] 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.

[0041] In the case of an oil-in-water emulsion, for example a care cream, the elastic mixture of the invention forms the continuous phase of said emulsion.

[0042] 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.

[0043] Another object of the invention relates to a process for preparing an elastic mixture according to the invention, as described previously, said process comprising a step of dissolving at least one polysaccharide a-, at least one polysaccharide b-, and at least one polyglycerol c-, in water d-.

[0044] Advantageously, the dissolution step is carried out, with stirring, at a temperature ranging from 50 to 90°C, and preferably from 70 to 90°C, for a period ranging from 5 minutes to 1 hour, and preferably for approximately 30 minutes. The mixture obtained at the end of the dissolution step is then cooled to room temperature (20°C).

[0045] During the dissolution step, the elastic mixture can be prepared by first dissolving the polyglycerol c- in water. The polysaccharide a- is then dissolved or dispersed in the mixture based on water and polyglycerol c-, with the optional addition of heat and stirring. Once the polysaccharide a- is dissolved or dispersed, the polysaccharide b- is then added, with the addition of heat to thoroughly homogenize the different components. Advantageously, the polysaccharide a- and the polysaccharide b- are added successively, with stirring, at a temperature ranging from 50 to 90°C, and preferably from 70 to 90°C, for a period ranging from 5 minutes to 1 hour, and preferably for approximately 30 minutes. The mixture obtained at the end of the dissolution step is then cooled to room temperature (20°C).The invention also relates to a process for preparing a cosmetic composition according to the invention, as described previously, said process comprising the following steps:

[0046] (i) preparation of an elastic mixture according to the invention by dissolving in water:

[0047] - at least one polysaccharide a- selected from chitosan, its salts, and their mixtures,

[0048] - at least one polysaccharide b- selected from pullulan, its salts, and their mixtures, and

[0049] - at least one polyglycerol c- of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 2 to 10, and

[0050] (ii) dispersion of the elastic mixture obtained in step (i) in an aqueous phase optionally comprising cosmetic active ingredients and / or excipients.

[0051] Advantageously, step (i) is carried out, with stirring, at a temperature ranging from 50 to 90°C, and preferably from 70 to 90°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 step (i), the elastic mixture can be prepared by first dissolving the polyglycerol c- in water. The polysaccharide a- is then dissolved or dispersed in the mixture based on water and polyglycerol c-, with the optional addition of heat and stirring. Once the polysaccharide a- is dissolved or dispersed, the polysaccharide b- is then added, with the addition of heat to thoroughly homogenize the different components. Advantageously, the polysaccharide a- and the polysaccharide b- are added successively, with stirring, at a temperature ranging from 50 to 90°C, and preferably from 70 to 90°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).

[0053] In step (ii), the mixture prepared in step (i) can be added to an aqueous phase comprising cosmetic active ingredients and / or other cosmetic excipients. According to another embodiment, the cosmetic composition of the invention is prepared by successively adding each of the components polysaccharide a-, polysaccharide b-, and polyglycerol c-, as defined according to the invention, directly into the aqueous phase of the cosmetic composition, without prior mixing. Advantageously, the components polysaccharide a-, polysaccharide b-, and polyglycerol c- are added successively, with stirring, at a temperature ranging from 50 to 90°C, and preferably from 70 to 90°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).

[0054] In the particular case of an emulsion, the fatty phase can be added to the aqueous phase comprising the elastic mixture.

[0055] Another subject of the invention relates to the use of an elastic mixture as defined according to the invention in a cosmetic composition as defined according to the invention intended to be applied to the skin, to form an elastic film providing a smoothing and / or sheathing effect on the skin.

[0056] Finally, a final object of the invention relates to a skin care method comprising a step of applying a cosmetic composition as defined according to the invention, to at least one part of the body and / or the face, for a smoothing and firming (firming) effect.

[0057] In one embodiment, the step of application to at least one part of the body and / or face is carried out on at least one area of ​​skin, in particular the face and / or décolleté, showing signs of aging or fatigue such as a loss of firmness, a loss of elasticity, or sagging skin, to obtain an effect chosen from a smoothing effect, a tightening effect, a skin plumping effect, or a combination of one of these effects.

[0058] The cosmetic composition directly applied to the skin forms, after application and gradual evaporation of the water in the composition, a film which has elastic-type mechanical properties with a texture which is particularly well suited to makeup. In addition, this type of texture has useful properties both in terms of aesthetics and comfort of use, particularly 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.

[0059] The skin care method may comprise the topical application to the areas of the skin concerned of an effective amount of a cosmetic composition according to the invention as defined above, to obtain a second skin sensation.

[0060] In addition to the preceding provisions, the invention also comprises other provisions which will emerge from the additional description which follows, which relates to the preparation and evaluation of elastic mixtures compared to elastic mixtures representative of the state of the art, as well as to the preparation of cosmetic compositions according to the invention.

[0061] Examples:

[0062] In the following examples, and unless otherwise indicated, all percentages are by weight, the ingredients are designated by their INCI name, and the temperature is indicated in degrees Celsius.

[0063] Example 1: Selection of plasticizer (polyglycerol c-') for the preparation of an elastic mixture with a smoothing effect according to the invention

[0064] This example aims to select a plasticizer (polyglycerol c-) allowing the preparation of a film obtained from an elastic mixture comprising a first polymer selected for its contraction properties and a second polymer selected for its elastic properties. The plasticizers tested are PROPYLENE GLYCOL (Control 1), VEGETABLE GLYCEROL (Control 2), POLYGLYCERIN-3 (Invention 1) and a POLYGLYCERIN-3 + POLYGLYCERIN-6 mixture (Invention 2). Table 1:

[0065] The elastic mixtures were prepared according to the following process:

[0066] The ingredients of phase A were mixed in a deflocculator at 85°C. Phase B was added to the previously prepared phase A.

[0067] The mixture was mixed at 400 rpm for 30 minutes at 85°C.

[0068] The resulting mixture was cooled to room temperature (20°C).

[0069] Phase C was added to the mixture at room temperature (20°C), and the resulting dispersion was mixed for 15 minutes. In vivo smoothing effect characterization test 4 hours:

[0070] The test consists of evaluating and comparing the smoothing and tightening effect on the area of ​​the corner of the eye called "crow's feet" after 4 hours on a panel of four volunteers.

[0071] The elastic mixture was applied to the crow's feet and then allowed to dry for 15 minutes. Visual observations were made immediately after drying and after 4 hours. Evaluation criteria:

[0072] +++ means that the product has a very significant smoothing / tightening effect on crow's feet,

[0073] ++ means the product has a significant smoothing / tightening effect on crow's feet, + means the product has a slightly visible smoothing effect on crow's feet, and

[0074] X means the product has no smoothing effect.

[0075] The results obtained for the four elastic mixtures tested are presented in Table 2 below:

[0076] Table 2:

[0077] Example 2: Effect of contractile polymer (polysaccharide a- 1 ) on the smoothing properties of the composition

[0078] This example aims to compare an elastic mixture according to the invention with a comparative elastic mixture free of contractile polymer (polysaccharide a).

[0079] Table 3:

[0080] The elastic mixtures were prepared according to the following process:

[0081] The ingredients of the Al phase were mixed in a deflocculator at 75°C.

[0082] Phases A2 and A3 were weighed and added to the previously prepared phase Al.

[0083] The mixture was mixed at 600 rpm for 30 minutes at 75°C.

[0084] The elastic mixtures obtained were cooled to room temperature (20°C).

[0085] In vivo smoothing effect characterization test 4 hours:

[0086] The same smoothing effect characterization test as described in Example 1 was carried out on the elastic mixtures in Table 3. The results obtained for the two mixtures tested are presented in Table 4 below:

[0087] Table 4:

[0088] Example 3: Care cream according to the invention

[0089] A care cream in the form of an oil-in-water emulsion corresponding to the composition of Table 5 below was prepared from an elastic mixture according to the invention. Table 5:

[0090] The composition was prepared according to the following process:

[0091] Phase A was dissolved in a Rayneri mixer at 80°C. Phases B1 and B2 were heated in a water bath at 80°C in a Rayneri mixer. Phase B3 was dispersed in the previously prepared phase and then mixed at 300 rpm for 30 minutes. Phase B4 was then added.

[0092] Phase A was dispersed into Phase B and then stirred for 10 minutes. Phase C was added to the previously prepared mixture and then dispersed for 2 minutes in an Ultra-Turrax™ mixer. The resulting mixture was heated to 45°C and then Phase D was added.

[0093] Once the composition had returned to room temperature, water was added to compensate for the water loss. Example 4: Care cream according to the invention

[0094] A care cream in the form of an oil-in-water emulsion corresponding to the composition of Table 6 below was prepared from an elastic mixture according to the invention.

[0095] Table 6:

[0096]

[0097] The composition was prepared according to the following process:

[0098] Phase A was solubilized in a Rayneri mixer at 80°C.

[0099] Phases B1 and B2 were heated in a water bath at 80°C in a Rayneri mixer. Phase B3 was dispersed in the previously prepared phase and then mixed at 300 rpm for 30 minutes. Phase B4 was then added.

[0100] Phase A was dispersed in phase B and then stirred for 10 minutes.

[0101] Phase C was added to the previously prepared mixture and then dispersed for 2 minutes in an Ultra-Turrax™ mixer.

[0102] The resulting mixture was heated to 45°C, then phase D was added.

[0103] Once the composition returned to room temperature, water was added to compensate for the water loss.

[0104] Example 5: Foundation according to the invention

[0105] A foundation in the form of an oil-in-water emulsion corresponding to the composition of Table 7 below was prepared from an elastic mixture according to the invention. Table 7:

[0106] The composition was prepared according to the following process:

[0107] The ingredients of phase A3 were mixed in a three-roll mill to disperse the pigments and form a pigment paste.

[0108] Phases Al and A2 were stirred in a Rayneri mixer at 200 rpm.

[0109] Phase A3 was added to the previously prepared phase in an Ultra-Turrax™ mixer, to obtain phase A.

[0110] Phase B1 was stirred at 500 rpm at 80°C. Phase B2 was added to phase B1, dispersed for 30 minutes (until completely dispersed), then cooled to room temperature (20°C).

[0111] Phase B3 has been added to Phase B.

[0112] Phase B4 was added to phase B. The emulsion was prepared by dispersing phase A into phase B at 1200 rpm for 3 minutes.

Claims

Claims 1. Elastic mixture characterized in that it comprises: a- at least one polysaccharide selected from chitosan, its salts, and their mixtures, b- at least one polysaccharide selected from pullulan, its salts, and their mixtures, and c- at least one polyglycerol of formula H-(O-CH2-CH(OH)-CH2)n-OH in which n varies from 2 to 10, and d- water.

2. Elastic mixture according to claim 1, characterized in that the polyglycerol c- is a polyglycerol of formula H-(O-CH2-CH(OH)-CH2) n - OH in which n varies from 2 to 6.

3. Elastic mixture according to claim 1 or claim 2, characterized in that the polyglycerol c- is a polyglycerol of formula H- (O-CH2-CH(OH)-CH2) n -OH in which n = 3 and / or 6 (POLYGLYCERIN-3 and / or POLYGLYCERIN-6).

4. Elastic mixture according to one of claims 1 to 3, characterized in that it comprises from 0.1 to 15%, preferably from 0.2 to 10%, and more preferably from 0.5 to 7%, by weight of polysaccharide a- relative to the total weight of said mixture.

5. Elastic mixture according to one of claims 1 to 4, characterized in that it comprises from 0.1 to 10%, preferably from 0.5 to 8%, and more preferably from 1 to 5%, by weight of polysaccharide b- relative to the total weight of said mixture.

6. Elastic mixture according to one of claims 1 to 5, characterized in that it comprises from 0.1 to 20%, preferably from 0.5 to 15%, and more preferably from 1 to 10%, by weight of polyglycerol c- relative to the total weight of said mixture.

7. Elastic mixture according to one of claims 1 to 6, characterized in that it comprises from 60 to 99%, preferably from 65 to 98%, and more preferably from 70 to 95%, by weight of water relative to the total weight of said mixture.

8. Cosmetic composition characterized in that it comprises an elastic mixture as defined according to one of claims 1 to 7.

9. Composition according to claim 8, characterized in that the elastic mixture represents from 10 to 100%, preferably from 15 to 95%, and more preferably from 15 to 90%, by weight relative to the total weight of the cosmetic composition.

10. Composition according to claim 8 or claim 9, characterized in that it comprises from 0.1 to 15%, preferably from 0.2 to 10%, and more preferably from 0.5 to 5%, by weight of polysaccharide a- relative to the total weight of said cosmetic composition.

11. Composition according to one of claims 8 to 10, characterized in that it comprises from 0.1 to 10%, preferably from 0.5 to 5%, and more preferably from 1 to 5%, by weight of polysaccharide b- relative to the total weight of the cosmetic composition.

12. Composition according to one of claims 8 to 11, characterized in that it comprises from 0.1 to 20%, preferably from 0.5 to 15%, and more preferably from 1 to 5%, by weight of polyglycerol c- relative to the total weight of the cosmetic composition.

13. Composition according to one of claims 8 to 12, characterized in that the mixture of polysaccharide a-, polysaccharide b- and polyglycerol c- (mixture of active ingredients) represents from 0.5 to 30%, preferably from 1 to 25%, and more preferably from 2 to 25%, by weight relative to the total weight of the cosmetic composition.

14. Composition according to one of claims 8 to 13, characterized in that it further comprises at least one cosmetic active ingredient, preferably chosen from a moisturizing agent, an anti-wrinkle agent, an antioxidant agent, an anti-free radical agent, an agent for repairing the effects destroyers of ultraviolet rays, or a slimming agent, and more preferably a cosmetic active ingredient chosen from hyaluronic acids.

15. Composition according to one of claims 8 to 14, characterized in that it is in the form of a gelled or non-gelled aqueous composition, a gelled or non-gelled emulsion, a cream, a serum, a mask, or a foundation.

16. Process for preparing an elastic mixture according to one of claims 1 to 7, characterized in that it comprises a step of dissolving at least one polysaccharide a-, at least one polysaccharide b-, and at least one polyglycerol c-, in water d-.

17. Process for preparing a cosmetic composition according to one of claims 8 to 15, characterized in that it comprises the following steps: (i) preparing an elastic mixture by dissolving at least one a-polysaccharide, at least one b-polysaccharide, and at least one c-polyglycerol, in d-water, and (ii) dispersion of the elastic mixture obtained in step (i) in an aqueous phase optionally comprising cosmetic active ingredients and / or excipients.

18. Use of an elastic mixture according to one of claims 1 to 7 in a cosmetic composition intended to be applied to the skin, to form an elastic film providing a smoothing and / or sheathing effect on the skin.

19. Skin care method characterized in that it comprises a step of applying a cosmetic composition as defined according to one of claims 8 to 15, to at least one part of the body and / or the face.

20. Method according to claim 19, characterized in that the step of application to at least one part of the body and / or the face is carried out on at least one area of skin, in particular of the face and / or of the décolleté, showing signs of aging or fatigue such as a loss of firmness, a loss of elasticity, or sagging skin, to obtain an effect chosen from a smoothing effect, a tightening effect, a skin plumping effect, or a combination of one of these effects.

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