Cosmetic composition in the form of aqueous core-shell spheroids based on chitosan

Abstract

The present invention relates to a cosmetic composition in the form of aqueous core-shell spheroids, comprising: a) an anionic polymer chosen from polyglutamic acid salts, and mixtures thereof, b) a cationic polymer which is CHITOSAN, and c) at least one hydrophilic gelling agent. The present invention also relates to a cosmetic composition in which the aqueous core-shell spheroids are suspended in a continuous gelled aqueous phase. The invention also relates to a method for preparing a cosmetic composition according to the invention, and also to a method for caring for the skin and / or the hair, comprising a step of applying a cosmetic composition according to the invention to at least one part of the body and / or of the face and / or of the hair.

Description

Description Title of the invention: Cosmetic composition in the form of aqueous core-bark type spheroids based on chitosan Technical Field The present invention relates to the cosmetic field, and more particularly to a cosmetic composition in the form of aqueous core-shell spheroids comprising a combination of a specific anionic polymer and a specific cationic polymer. The present invention also relates to a method for preparing a cosmetic composition according to the invention, as well as a method for skin and / or hair care comprising a step of applying a cosmetic composition according to the invention to at least one part of the body and / or face and / or hair.

[0002] Mixing an anionic polymer and a cationic polymer in aqueous solution generally results in segregative phase separation, leading to the formation of two distinct phases, each enriched in one of the polymers. This phase separation arises from the incompatibility between the two polymers and becomes more pronounced as the concentrations or molar masses of the polymers increase.

[0003] The inventors have surprisingly observed that combining an anionic polymer based on a salt of polyglutamic acid and a cationic polymer based on chitosan, normally incompatible due to their thermodynamic instability, allows for the production of macroscopic aqueous spheroids visible to the naked eye with a homogeneous spherical shape. The inventors have also observed that chitosan, usually difficult to work with due to its high stickiness and cationic nature, exhibits very low (or even no) stickiness when formulated as an aqueous gel within core-shell-type aqueous spheroids. This gelled spheroidal structure further enhances the contractile properties (smoothing / tightening effect) of chitosan. Thus, the cosmetic composition of the invention based on aqueous chitosan spheroids exhibits improved efficacy in terms of The cosmetic composition of the invention provides a skin-smoothing / tightening effect and is non-sticky. Furthermore, it allows for rapid penetration of the chitosan and its constituent cosmetic actives, providing a cooling effect and a sensory experience distinct from conventional products, with a soft and luminous finish, as well as a "second skin" effect when applied to the skin. The cosmetic composition of the invention also exhibits improved hydration efficacy. It also leads to a reduction in transepidermal water loss (TEWL), which corresponds to the amount of water vapor that naturally escapes through the skin barrier. Thus, transepidermal water loss is an indicator of the skin's ability to retain moisture and, therefore, its capacity to maintain good skin hydration. Brief description of the drawings

[0004] The attached drawings are schematic and are primarily intended to illustrate the principles of the invention.

[0005] [Fig. 1] and [Fig. 2] Figures 1 and 2 represent aqueous core-bark type spheroids according to the invention. Description of the invention

[0006] The present invention relates to a cosmetic composition in the form of aqueous core-shell type spheroids, comprising: a) an anionic polymer selected from the salts of polyglutamic acid, and their mixtures, and preferably SODIUM POLYGLUTAMATE, b) a cationic polymer which is CHITOSAN, and c) at least one hydrophilic gelling agent.

[0007] For the purposes of this invention, the term "spheroid" refers to a spherically shaped ball having the same composition throughout. The spheroids of this invention preferably have a regular appearance, a smooth surface, and a uniform volume. The diameter of the spheroids can vary from 0.05 to 20 mm, preferably from 0.1 to 10 mm. mm, and more preferably from 0.2 to 5 mm, this diameter being an average diameter measured over ten measurements using a conventional method, for example with a graduated ruler. The spheroids of the invention are of the core-shell type, the shell of which can break under slight shear.

[0008] The hardness of the spheroids of the invention can be measured at 20°C using a TAXTPIus texture analyzer from Stable Micro Systems. The hardness of the spheroids of the invention is expressed in Newtons (N) and is advantageously greater than 0.05 N. According to a particular and preferred method, the hardness of the spheroids according to the invention varies from 0.05 to 2 N.

[0009] In one embodiment, the cationic polymer b) can be used in a mixture with an additional cationic polymer, preferably selected from the Ci-Ce hydroxyalky quaternary ammonium salts of guar gum, the polyquaterniums, and mixtures thereof.

[0010] In this embodiment, the quaternary hydroxyalkyl ammonium salt in C1-CO of guar gum is preferably GUAR HYDROXYPROPYLTRIMONIUM CHLORIDE.

[0011] In this embodiment, the polyquaternium is preferably selected from polyquaternium-6, polyquaternium-7, polyquaternium-22, polyquaternium-47, polyquaternium-67, and mixtures thereof, and more preferably from polyquaternium-6. For the purposes of this invention, "polyquaternium" means a polymer or copolymer comprising one or more quaternary ammonium groups. It is a category of cationic polymers used in skincare, makeup, and haircare products.

[0012] In a preferred embodiment, the gelling agent (c) is a nonionic gelling agent, preferably selected from natural or synthetic polysaccharides, hydrophilic urethane polymers modified by a hydrophobic group, and mixtures thereof. More preferably, the gelling agent (c) is selected from SCLEROTIUM GUM, HYDROXYPROPYL STARCH PHOSPHATE, SPHINGOMONAS FERMENT EXTRACT, PEG-240 / HDI COPOLYMER BIS- DECYLTETRADECETH-20 ETHER, HYDROXYETHYL CELLULOSE, CELLULOSE GUM, AGAR, TAMARINDUS INDICA SEED GUM, and mixtures thereof.

[0013] The anionic polymer a) may represent from 0.05 to 5% by weight, preferably from 0.1 to 3% by weight, and more preferably from 0.2 to 2% by weight, relative to the total weight of the cosmetic composition.

[0014] The cationic polymer b) can represent from 0.1 to 15% by weight, preferably from 0.2 to 10% by weight, and more preferably from 0.5 to 8% by weight, relative to the total weight of the cosmetic composition.

[0015] The total of anionic polymer a) and cationic polymer b) may represent at least 0.2% by weight, preferably from 0.5 to 20% by weight, and more preferably from 1 to 15% by weight, relative to the total weight of the cosmetic composition.

[0016] The ratio of anionic polymer a) to cationic polymer b) advantageously varies from 1 / 1 to 1 / 8, and preferably from 1 / 2 to 1 / 5. In a preferred embodiment, the ratio of anionic polymer a) to cationic polymer b) is 1 / 4.

[0017] In a preferred embodiment of the cosmetic composition of the invention: - the core of the spheroids consists of the cationic polymer b) CHITOSAN and at least one hydrophilic gelling agent c), and - the spheroid's bark is made up of the anionic polymer a) chosen from the salts of polyglutamic acid, and their mixtures, and the cationic polymer b) CHITOSAN.

[0018] In one embodiment, the spheroid shell is made of the anionic polymer a) selected from the salts of polyglutamic acid, and their mixtures, and the cationic polymer b) CHITOSAN, and is made of a single layer.

[0019] The aqueous core-bark type spheroids of the invention can be used as such in a cosmetic composition, or alternatively be suspended in a continuous phase, said continuous phase being a continuous aqueous phase, a continuous oily phase, an oil-in-water emulsion, or a water-in-oil emulsion.

[0020] Thus, in a particular embodiment of the invention, the cosmetic composition of the invention consists of aqueous spheroids suspended in a continuous phase. Therefore, the aqueous spheroids of the invention can be incorporated: - either in a continuous aqueous gelled phase or in the continuous aqueous phase of a water-in-oil emulsion or an oil-in-water emulsion, - either in a continuous gelled oily phase or in the continuous gelled oily phase of an oil-in-water emulsion (to obtain a water-in-oil-in-water emulsion) or of a water-in-oil emulsion (to obtain a water-in-water-in-oil emulsion).

[0021] In this embodiment, the continuous phase is an aqueous continuous phase advantageously comprising at least one hydrophilic gelling agent, preferably a translucent hydrophilic gelling agent having a suspending power.

[0022] The term "translucent" refers to a gelling agent that allows light to pass through but is not transparent. Thus, a "translucent" gelling agent allows light rays to pass through but does not allow the outlines of the core-shell aqueous spheroids suspended within it to be clearly distinguished. "Suspensive power" refers to a gelling agent capable of increasing the viscosity of the continuous gelled aqueous phase in order to improve the suspensive character (or power) of said continuous gelled aqueous phase, particularly with respect to the core-shell aqueous spheroids. This translucent hydrophilic gelling agent with "suspensive power" stabilizes the core-shell aqueous spheroids within the continuous gelled aqueous phase, and in particular prevents and / or avoids the coalescence of the aqueous spheroids with each other and / or their creaming or sedimentation in the continuous gelled aqueous phase. [0023JA As examples of hydrophilic gelling agents, we can mention: - acrylic and methacrylic acid polymers and copolymers, - carboxyvinyl polymers, - polysaccharide gelling agents, - mineral gelling agents, and their mixtures.

[0024] In a preferred embodiment, the hydrophilic gelling agent of said aqueous continuous phase is a polysaccharide gelling agent, preferably selected from alginates, natural or modified gums such as agar gums, guar gums, gellan gums, mannans, cellulose derivatives, gelatin, pectins, and mixtures thereof.

[0025] In a more preferred embodiment, the hydrophilic gelling agent of said aqueous continuous phase is selected from SCLEROTIUM GUM, SPHINGOMONAS FERMENT EXTRACT, HYDROXYETHYL CELLULOSE, AGAR, XANTHAN GUM, CELLULOSE GUM, CARBOMER, HYDROXYPROPYL STARCH PHOSPHATE, GLUCOMANNAN, and mixtures thereof.

[0026] In another embodiment, the continuous phase is an oily continuous phase advantageously comprising at least one oil-phase texturizing agent.

[0027] An "oil-phase texturizing agent" is a compound capable of thickening the oils contained in the composition. These oil-phase texturizing agents can be chosen from among synthetic or natural waxes, mineral or organic oil-phase gelling agents, and pasty fats.

[0028] When the cosmetic composition of the invention consists of aqueous spheroids suspended in a continuous phase, the ratio between the aqueous spheroids and the continuous phase varies preferably from 90 / 10 to 1 / 99, and more preferably from 80 / 20 to 60 / 40.

[0029] In one embodiment, the cosmetic composition of the invention may comprise at least one cosmetic active ingredient, preferably selected from glycolic acid, zinc PCA (marketed under the name Zincidone®), citric acid, trisodium citrate, and mixtures thereof. Said cosmetic active ingredient may be present in the aqueous spheroids of core-bark type and / or in the continuous phase when the aqueous core-bark type spheroids are suspended in such a phase.

[0030] In one embodiment, the cosmetic composition of the invention may comprise at least one pearlescent pigment, preferably within aqueous core-shell spheroids. The pearlescent pigments may advantageously be selected from alumina, silica, calcium sodium borosilicate, calcium aluminum borosilicate, aluminum, and mixtures thereof. For example, the product SilikMira Sleek VRO, marketed by Sandream Specialties, which is a mixture of silica, titanium dioxide, and calcium sodium borosilicate, or the product Timiron® Halo White (SYNTHETIC FLUORPHLOGOPITE and TIN OXIDE), marketed by Merck KGaA, may be used.

[0031] Another object of the invention relates to a method for preparing a cosmetic composition according to the invention, as described above.

[0032] The process for preparing the cosmetic composition according to the invention comprises the following steps: (i) under stirring, preparation of an aqueous gel of anionic polymer a) by mixing water with an anionic polymer a) selected from the salts of polyglutamic acid, and mixtures thereof, advantageously at a pH between 8 and 12.5, and preferably at a temperature from 60 to 100°C, (ii) under stirring, preparation of an aqueous cationic polymer gel b) by mixing water with a cationic polymer b), which is chitosan, and a hydrophilic gelling agent c), (iii) under stirring, incorporation of the aqueous anionic polymer gel a) formed in step (i), drop by drop, preferably using a syringe, into the aqueous cationic polymer gel b) formed in step (ii), to form aqueous spheroids preferably having a size of 0.05 to 20 mm, suspended in the aqueous cationic polymer gel b), (iv) under agitation, maintaining the aqueous spheroids formed in step (iii) in suspension in the aqueous cationic polymer gel (b), for a period of at least 10 minutes, and preferably for a period of 10 to 45 minutes, until a bark forms around the aqueous spheroids, (v) filtration and washing of aqueous spheroids, (vi) Optionally, incorporation of the aqueous spheroids obtained in step (v) into a continuous phase preferably comprising at least one gelling agent, the weight ratio between the aqueous spheroids and the continuous phase preferably ranging from 90 / 10 to 1 / 99, and more preferably from 60 / 40 to 80 / 20.

[0033] In a preferred embodiment, a base is added during step (i) of preparation of the aqueous gel of anionic polymer a). This base is preferably a strong base, and more preferably sodium hydroxide (NaOH).

[0034] The inventors observed that the preparation of an aqueous gel of anionic polymer a) at a pH between 8 and 12.5 and / or in the presence of a base such as NaOH, during step (i), improves the stability over time of the cosmetic composition of the invention in the form of aqueous core-bark type spheroids.

[0035] The aqueous anionic polymer gel a) prepared in step (i) preferably has a viscosity of 0 to 300 mPa.s at 20°C, and more preferably of 0 to 70 mPa.s at 20°C.

[0036] The aqueous cationic polymer gel b) prepared in step (i) has a viscosity ranging from 60 to 3,600 mPa.s at 20°C, and preferably from 100 to 1,500 mPa.s at 20°C.

[0037] In one embodiment, the incorporation by drop of the aqueous anionic polymer gel a) formed in step (i) into the aqueous cationic polymer gel b) formed in step (ii) is carried out by placing the drop at a height of at least 3 cm, and preferably at a height of 5 to 30 cm, above the aqueous cationic polymer gel b).

[0038] In the optional step (vi), the resulting aqueous spheroids can be incorporated: - either in a continuous aqueous gelled phase or in the continuous aqueous phase of a water-in-oil emulsion or an oil-in-water emulsion, - either in a continuous gelled oil phase or in the continuous gelled oil phase of an oil-in-water emulsion (to obtain a water- in-oil-in-water) or a water-in-oil emulsion (to obtain a water-in-water-in-oil emulsion).

[0039] Finally, a last object of the invention relates to a skin and / or hair care process comprising a step of applying a cosmetic composition as defined according to the invention, to at least one part of the body and / or face and / or hair.

[0040] In addition to the foregoing provisions, the invention includes further 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. Examples:

[0041] In the examples that follow, 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.

[0042] The characterization methods used in the examples are as follows:

[0043] Viscosity measurement: Viscosity was measured using a Rhéolab® rotational rheometer with a CC27 coaxial cylindrical spindle.

[0044] Analysis by optical microscopy: The compositions of the specimens were observed under an optical microscope, and their spherical or non-spherical shape was determined visually. Spheroids have a spherical shape when their outer layer is sufficiently rigid to maintain this shape over time. Spheroids that lack sufficient hardness (are too soft) do not maintain their spherical shape over time. The optical microscopy analysis method made it possible to highlight the shape of the spheroids and to observe their size and shape. ++: perfectly spherical shape, and x: non-spherical shape.

[0045] Evaluation of the stability of the compositions: The stability of the compositions was evaluated after oven curing at temperatures of 4°C, 45°C and 50°C, after one week. The overall stability of each composition was categorized as follows: ++: very good stability (homogeneous formula), +: good stability (slight reversible phase shift), x: not stable (irreversible phase shift).

[0046] Measurement of spheroid hardness: The hardness of the spheroids was measured at 20°C using a TAXTPIus texture analyzer from Stable Micro Systems, equipped with a 500 g sensor. The instrument used was a 20 mm diameter stainless steel cylinder. The measurement consisted of measuring the force as a function of the spheroid's crushing distance, at a speed of 1 mm / s, up to 80% of its size, a value sufficient to exceed the distance required for bursting / fracture. The results extracted at the point of bursting / fracture of the spheroid are expressed in Gram-force (Gf) and converted to Newtons (N).

[0047] Hydration level measurement: Hydration levels were measured by corneometry using a Corneometer® CM825 device provided by Courage & Khazaka. The method for measuring stratum corneum hydration relies on creating an electric field at the skin surface and detecting, using electrodes, the variations in the dielectric constant induced by the hydration status of the uppermost layer of the epidermis. The composition was applied to the forearm of a volunteer. The quantity applied corresponds to 2 pL. 2 of composition on the skin. The test was carried out on a panel of 11 subjects. The application area was then protected from friction by placing a metal ring around the area application, fixed to the forearm using adhesive tape. Hydration levels were measured on the application area before (TO) application of the cosmetic composition, and then again 6 hours after application (T6h), with a 15-minute stabilization period following removal of the anti-friction protection before each measurement. The change in hydration between the TO and T6h measurements was calculated as a percentage.

[0048] Measurement of Insensible Water Loss (IWL): The skin barrier strengthening properties were assessed by measuring Insensible Water Loss (IWL) using a vaporometer. The composition was applied to the forearm of a volunteer. The quantity applied corresponded to 2 pL.cnr 2of composition on the skin. The test was carried out on a panel of 11 subjects. The application area was then protected from friction by placing a metal ring around the application area, fixed to the forearm with adhesive tape. A PIE measurement was taken on the application area before (TO) application of the cosmetic composition, and then 6 hours after application (T6h), allowing a 15-minute stabilization period after removal of the anti-friction protection before taking the measurement. The change in PIE between the measurements at TO and T6h was calculated as a percentage.

[0049] Characterization of the smoothing / tightening effect in vivo after 4 hours: The test consists of evaluating and comparing the smoothing and tightening effect on the area at the corner of the eye called "crow's feet" after 4 hours on a panel of three volunteers. The cosmetic composition was applied to the crow's feet and then left to dry. Visual observations were made after 4 hours. Evaluation criteria: +++ means that the cosmetic composition has a very strong smoothing / tightening effect significant on the crow's foot, ++ means that the cosmetic composition has a significant smoothing / tightening effect on crow's feet. + means that the cosmetic composition has a slightly visible smoothing effect on crow's feet, and x means that the cosmetic composition has no smoothing effect. Example 1: Preparation of cosmetic compositions in the form of aqueous core-shell type spheroids

[0050] Chitosan-based spheroids according to the invention, comprising various hydrophilic gelling agents, and comparative spheroids, were prepared and evaluated. The values ​​shown in the table are percentages by weight.

[0051] [Table 1]

[0052] The protocol for preparing cosmetic compositions in the form of aqueous core-bark type spheroids was as follows:

[0053] Preparation of the cationic polymer gel b): The phase containing water and the preservative was heated to 80°C. Once the mixture was homogenized, the hydrophilic gelling agent (SPHINGOMONAS FERMENT EXTRACT) was added. The mixture was then stirred using a Rayneri deflocculator at 500 rpm for 20 minutes. The cationic polymer b) was then added, and the mixture was stirred for 10 minutes. The resulting cationic polymer b) gel was cooled to 35°C, then compensated by adding water, and finally packaged in a transparent bottle.

[0054] Preparation of the anionic polymer bath a): The phase containing water and preservative was heated to 80°C. Once the mixture was homogenized, the anionic polymer a) was added and the mixture was stirred using a Rayneri deflocculator at 500 rpm for 20 minutes. The anionic polymer a) bath was cooled to 35°C, then topped up with water, and finally packaged in a transparent bottle.

[0055] Production of aqueous core-bark type spheroids: The previously prepared cationic polymer gel (b) was added dropwise using an automatic syringe to the previously prepared anionic polymer bath (a), while stirring. The height between the tip of the syringe needle and the surface of the aqueous anionic polymer gel bath (a) was set at 15 cm. The formation of aqueous spheroids within the anionic polymer bath (a) was observed, along with the formation of a bark. The solution was white, with the spheroids remaining in the bath for 15 minutes under agitation. The resulting spheroids were filtered through a sieve and then rinsed with distilled water for 10 minutes under agitation. This rinsing step was repeated three times. The aqueous spheroids were again filtered through a sieve and then stored in a transparent bottle. Results :

[0056] The prepared spheroids were visually inspected to confirm their formation and verify their sphericity. The results are shown in the following table:

[0057] [Table 2]

[0058] For the spheroids of the Control 1 formula, the cationic polymer gel did not allow the formation of spherical spheroids at the time of the drop-by-drop introduction of the cationic gel into the bath comprising the anionic polymer, unlike the spheroids of Inventions 1, 2 and 3.

[0059] The spheroids of invention 3 have an average diameter of 3 mm and a homogeneous spherical shape as shown in Figure 1. The hardness of the spheroids of invention 3 measured according to the method described above is 0.12 N. Example 2: Methods for preparing spheroids according to the invention

[0060] Two methods for preparing spheroids according to the invention were implemented. The values ​​shown in the table are percentages by weight.

[0061] [Table 3]

[0062] Aqueous core-bark type spheroids were prepared according to the following protocol:

[0063] Preparation of the cationic polymer gel b): The preparation of the cationic polymer gel b) was identical to that described in example 1, substituting the gelling agent SPHINGOMONAS FERMENT EXTRACT with SCLEROTIUM GUM.

[0064] Preparation of the anionic polymer bath a): The phase containing water and preservative was heated to a temperature of 80°C. Once the mixture was homogenized, the anionic polymer a) was added and the mixture was stirred using a Rayneri deflocculator at 500 rpm for 20 minutes. Tri-sodium citrate or sodium hydroxide was added to reach the pH of 12.3. The anionic polymer bath a) was cooled to a temperature of 35°C, then compensated by adding water, and finally packaged in a transparent bottle.

[0065] Preparation of aqueous core-bark spheroids: Aqueous core-bark spheroids were prepared using the drop-by-drop method described in Example 1. The formation of aqueous spheroids within the anionic polymer bath (a) was observed, with the formation of a white bark. The contact time of the spheroids in the bath was set at 15 minutes, with stirring. The spheroids thus obtained were filtered through a sieve and then rinsed with distilled water for 10 minutes with stirring. This rinsing step was repeated three times. The aqueous spheroids were again filtered through a sieve and then stored in a transparent bottle. Results :

[0066] The spheroids formed from the formulas of Inventions 4 and 5 were visually inspected to verify their sphericity. The stability results for these spheroids are shown in the following table:

[0067] [Table 4]

[0068] Increasing the pH of the anionic polymer bath, into which the cationic polymer gel was dropwise added, facilitated easier recovery (rinsing and conditioning) of the spheroids and also led to improved spheroid stability after one week in the oven. Adding a base to the anionic polymer bath rendered the chitosan-based cationic polymer gel insoluble at the cationic gel / anionic bath interface, resulting in the formation of spherical beads with improved stability that did not stick together. Example 3: Preparation of a cosmetic composition of aqueous spheroids suspended in a continuous gelled aqueous phase according to the invention

[0069] A cosmetic composition according to the invention, comprising spheroids based on chitosan and sodium polyglutamate, suspended in a continuous gelled aqueous phase, was prepared and evaluated. The values ​​shown in the table are percentages by weight.

[0070] [Table 5]

[0071] Aqueous core-bark type spheroids according to the formula of invention 6 were prepared according to the following protocol:

[0072] Preparation of the cationic polymer gel b): The cationic polymer gel b) was prepared according to the same protocol as described in example 2.

[0073] Preparation of the anionic polymer bath a): The anionic polymer bath (a) was prepared according to the same protocol as described in Example 2. The pH of the anionic polymer bath (a) was maintained at approximately 12 by adding a strong base. Nacres were added to the cationic polymer gel after the addition and homogenization of the cationic polymer. The mixture was then stirred using a Rayneri deflocculator at 300 rpm, cooled to 35°C, compensated by adding water, and finally packaged in a transparent bottle.

[0074] Production of aqueous core-bark type spheroids: The aqueous core-bark type spheroids were prepared using the same drop-by-drop method described in Example 1, and then stored in a transparent bottle.

[0075] Incorporation of aqueous core-bark type spheroids into a continuous gelled aqueous phase: an aqueous gel corresponding to the formula in Table 6 below was prepared to disperse the spheroids of the invention 6 previously prepared.

[0076] [Table 6]

[0077] The aqueous phase was heated to 80°C, then the hydrophilic gelling agent was added and the mixture was stirred using a Rayneri deflocculator at 500 rpm for 20 minutes. Sodium hydroxide and lactic acid were added to neutralize the hydrophilic gelling agent and adjust the pH at 6. The resulting gelled aqueous phase was cooled to a temperature of 35°C, then compensated by adding water, and finally packaged in a transparent bottle.

[0078] The previously prepared aqueous core-bark spheroids of invention 6 were suspended in the continuous aqueous gel phase. The cosmetic composition, consisting of the continuous aqueous gel phase in which the spheroids were dispersed, was packaged in a container and photographed in Figure 2.

[0079] Applying the prepared cosmetic composition to the skin produces a pleasant sensation, notably an absence of stickiness despite the presence of chitosan, which is usually known for its adhesive properties. This is due to the chitosan's encapsulation within the spheroids. The application of the cosmetic composition also produces a noticeably improved tightening effect. Example 4: Preparation of a comparative cosmetic composition based on SUCCINYL CHITOSAN

[0080] A comparative cosmetic composition was prepared according to the same protocol as that described in Example 3, but replacing CHITOSAN with SUCCINYL CHITOSAN (INCI name: CHITOSAN SUCCINAMIDE). This comparative composition corresponds to the following formula (the values ​​indicated in the table are % by weight):

[0081] [Table 7]

[0082] This composition did not allow the formation of aqueous core-bark spheroids as defined by the invention. The use of SUCCINYL CHITOSAN instead of CHITOSAN resulted in a monophasic composition. Due to the anionic nature of SUCCINYL CHITOSAN, it does not allow the formation of aqueous core-bark spheroids with a homogeneous spherical shape, visible to the naked eye. Example 5: Preparation of a cosmetic composition of aqueous spheroids suspended in a continuous gelled aqueous phase according to the invention

[0083] A cosmetic composition according to the invention comprising spheroids based on CHITOSAN and SODIUM POLYGLUTAMATE, corresponding to the following formula, was prepared according to the protocol described in Example 3. The values ​​indicated in the table are % by weight.

[0084] [Table 8]

[0085] Incorporation of aqueous core-shell spheroids into a continuous aqueous gel phase: an aqueous gel conforming to the following formula was prepared for dispersing the spheroids of the invention 7 previously prepared. The aqueous gel phase was prepared according to the protocol described in Example 3. The values ​​indicated in the table are weight percentages.

[0086] [Table 9]

[0087] The resulting cosmetic composition (gelled aqueous phase into which the aqueous spheroids are incorporated) has the following characteristics:

[0088] [Table 10] Example 6: Preparation of a cosmetic composition of aqueous spheroids suspended in a continuous gelled aqueous phase according to the invention

[0089] A cosmetic composition according to the invention comprising spheroids based on CHITOSAN and SODIUM POLYGLUTAMATE, corresponding to the following formula, was prepared according to the protocol described in Example 3. The values ​​indicated in the table are % by weight.

[0090] [Table 11]

[0091] Incorporation of aqueous core-bark spheroids into a continuous aqueous gel phase: an aqueous gel conforming to the following formula was prepared for dispersing the previously prepared spheroids. The aqueous gel phase was prepared according to the protocol described in Example 3. The values ​​shown in the table are weight percentages.

[0092] [Table 12]

[0093] The resulting cosmetic composition is in the form of aqueous spheroids suspended in a continuous gelled aqueous phase. Example 7: Preparation of a cosmetic composition of aqueous spheroids suspended in a continuous gelled aqueous phase according to the invention

[0094] A cosmetic composition according to the invention comprising spheroids based on CHITOSAN and SODIUM POLYGLUTAMATE, corresponding to the following formula, was prepared according to the protocol described in Example 3. The values ​​indicated in the table are % by weight.

[0095] [Table 13]

[0096] Incorporation of aqueous core-bark spheroids into a continuous aqueous gel phase: an aqueous gel conforming to the following formula was prepared for dispersing the previously prepared spheroids. The aqueous gel phase was prepared according to the protocol described in Example 3. The values ​​shown in the table are weight percentages.

[0097] [Table 14]

[0098] The resulting cosmetic composition is in the form of aqueous spheroids suspended in a continuous gelled aqueous phase.

Claims

Demands

1. Cosmetic composition in the form of aqueous core-shell type spheroids, characterized in that it comprises: a) an anionic polymer selected from the salts of polyglutamic acid, and mixtures thereof, b) a cationic polymer which is CHITOSAN, and c) at least one hydrophilic gelling agent.

2. Cosmetic composition according to claim 1, wherein the anionic polymer a) is SODIUM POLYGLUTAMATE.

3. Cosmetic composition according to claim 1 or claim 2, wherein the cationic polymer b) is used in mixture with an additional cationic polymer, preferably selected from the Ci-Ce hydroxyalky quaternary ammonium salts of guar gum, the polyquaterniums, and mixtures thereof, and more preferably selected from GUAR HYDROXYPROPYLTRIMONIUM CHLORIDE, POLYQUATERNIUM-6, POLYQUATERNIUM-7, POLYQUATERNIUM-22, POLYQUATERNIUM-47, POLYQUATERNIUM-67, and mixtures thereof.

4. Cosmetic composition according to any one of claims 1 to 3, wherein the gelling agent c) is a non-ionic gelling agent, preferably selected from natural or synthetic polysaccharides, hydrophilic urethane polymers modified by a hydrophobic group, and mixtures thereof.

5. Cosmetic composition according to claim 4, wherein the gelling agent c) is selected from SCLEROTIUM GUM, HYDROXYPROPYL STARCH PHOSPHATE, SPHINGOMONAS FERMENT EXTRACT, PEG-240 / HDI COPOLYMER BIS-DECYLTETRADECETH-20 ETHER, HYDROXYETHYL CELLULOSE, CELLULOSE GUM, AGAR, TAMARINDUS INDICA SEED GUM, and mixtures thereof.

6. Cosmetic composition according to any one of claims 1 to 5, wherein the spheroids have a size ranging from 0.05 to 20 mm, preferably from 0.1 to 10 mm, and more preferably from 0.2 to 5 mm.

7. Cosmetic composition according to any one of claims 1 to 6, wherein the anionic polymer a) represents from 0.05 to 5% by weight, preferably from 0.1 to 3% by weight, and more preferably from 0.2 to 2% by weight, relative to the total weight of the cosmetic composition.

8. Cosmetic composition according to any one of claims 1 to 7, wherein the cationic polymer b) represents from 0.1 to 15% by weight, preferably from 0.2 to 10% by weight, and more preferably from 0.5 to 8% by weight, relative to the total weight of the cosmetic composition.

9. Cosmetic composition according to any one of claims 1 to 8, wherein the total of anionic polymer a) and cationic polymer b) represents at least 0.2% by weight, preferably from 0.5 to 20% by weight, and more preferably from 1 to 15% by weight, relative to the total weight of the cosmetic composition.

10. Cosmetic composition according to any one of claims 1 to 9, wherein the ratio of anionic polymer a) / cationic polymer b) varies from 1 / 1 to 1 / 8, preferably from 1 / 2 to 1 / 5, and more preferably is 1 / 4.

11. A cosmetic composition according to any one of claims 1 to 10, wherein: - the core of the spheroids consists of the cationic polymer b) CHITOSAN and at least one hydrophilic gelling agent c), and - the spheroid's bark is made up of the anionic polymer a) chosen from the salts of polyglutamic acid, and their mixtures, and the cationic polymer b) CHITOSAN.

12. Cosmetic composition according to any one of claims 1 to 11, wherein the aqueous spheroids are suspended in a continuous gelled aqueous phase.

13. A cosmetic composition according to claim 12, wherein the continuous gelled aqueous phase comprises at least one translucent hydrophilic gelling agent having suspending power, preferably selected from natural or synthetic polysaccharides, acrylic acid polymers, and mixtures thereof, and more preferably selected from the SCLEROTIUM GUM, SPHINGOMONAS FERMENT EXTRACT, HYDROXYETHYL CELLULOSE, IAGAR, XANTHAN GUM, CELLULOSE GUM, CARBOMER, HYDROXYPROPYL STARCH PHOSPHATE, GLUCOMANNAN, and mixtures thereof.

14. Cosmetic composition according to claim 12 or claim 13, characterized in that the ratio between aqueous spheroids and continuous gelled aqueous phase varies from 90 / 10 to 1 / 99, and preferably from 80 / 20 to 60 / 40.

15. Cosmetic composition according to any one of claims 1 to 14, characterized in that it comprises at least one pearlescent pigment, preferably selected from alumina, silica, calcium sodium borosilicate, calcium aluminium borosilicate, aluminium, and mixtures thereof.

16. A method for preparing a cosmetic composition according to any one of claims 1 to 15, characterized in that it comprises the following steps: (i) under stirring, preparation of an aqueous anionic polymer gel a) by mixing water with an anionic polymer a) selected from the salts of polyglutamic acid, and mixtures thereof, advantageously at a pH between 8 and 12.5, and preferably at a temperature from 60 to 100°C, said aqueous anionic polymer gel a) preferably having a viscosity from 0 to 300 mPa.s at 20°C, and more preferably from 0 to 70 mPa.s at 20°C, (ii) under stirring, preparation of an aqueous cationic polymer gel b) by mixing water with a cationic polymer b), which is chitosan, and a hydrophilic gelling agent c), said aqueous cationic polymer gel b) having a viscosity of 60 to 3,600 mPa.s at 20°C, and preferably of 100 to 1,500 mPa.s at 20°C, (iii) Under stirring, incorporating the aqueous anionic polymer gel a) formed in step (i), dropwise, preferably using a syringe, into the aqueous cationic polymer gel b) formed in step (ii), and preferably by placing the drip at a height of at least 3 cm, and preferably at a height of 5 to 30 cm, above the aqueous cationic polymer gel b), to form aqueous spheroids preferably having a size ranging from 0.05 to 20 mm, suspended in the aqueous cationic polymer gel b), (iv) under agitation, maintaining the aqueous spheroids formed in step (iii) in suspension in the aqueous cationic polymer gel (b), for a period of at least 10 minutes, and preferably for a period of 10 to 45 minutes, until a bark forms around the aqueous spheroids, (v) filtration and washing of aqueous spheroids, (vi) Optionally, incorporation of the aqueous spheroids obtained during the step (v) in a continuous gelled aqueous phase preferably comprising at least one translucent hydrophilic gelling agent having a suspending power.

17. A method according to claim 16, characterized in that a base is added during step (i) of preparing the aqueous gel of anionic polymer a), said base preferably being sodium hydroxide (NaOH).

18. A skin and / or hair care method characterized in that it comprises a step of applying a cosmetic composition according to any one of claims 1 to 15, on at least one part of the body and / or face and / or hair.

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