WO2012022858A1

WO2012022858A1 - Method for preparing and packaging a cosmetic pharmaceutical hydrogel to be applied to the skin

Info

Publication number: WO2012022858A1
Application number: PCT/FR2011/000456
Authority: WO
Inventors: Alain Finet; Jingkang Xu
Original assignee: Laboratoires Crystale De Collagena; Zhu Hai Haishilong Bio-Tech Co.Ltd.
Priority date: 2010-08-17
Filing date: 2011-08-03
Publication date: 2012-02-23
Also published as: FR2963888A1; FR2963888B1

Abstract

The present invention relates to a method for preparing, producing, and packaging a hydrogel to be applied to the skin in a thin layer, containing a gelling and thickening complex including carrageenan, glucomannan and galactomannan. Specifically, said hydrogel is provided in the form of a mask or patches in a kit for the cosmetic care of the face. The hydrogel of the invention is obtained and packaged according to a method including a first step of forming the hydrogel by the application of a negative heat shock inside the packaging thereof, then a second step of adding the cosmetic or pharmaceutical active principles in the form of a concentrated liquid composition, and a third step in which the packaging is hermetically sealed.

Description

Process for preparing and conditioning a cosmetic pharmaceutical hydrogel intended to be applied to the skin

The present invention relates to the preparation of cosmetic and pharmaceutical compositions in the form of a hydrogel, intended to be applied to the skin.

This invention particularly relates to a process for preparing and conditioning a thin hydrogel based on a natural thickener and gelling complex comprising carrageenan, glucommanane and galactomannan.

For several years have developed skin care where the cosmetic or pharmaceutical agents are formulated as a hydrogel, that is to say in the form of gelled aqueous compositions.

These hydrogels have developed more particularly in the field of facials, in the form of hydrogel masks or patches, which are an alternative to the use of creams or serums.

The use of hydrogels has several advantages including, in particular, the fact of being able to treat at the same time, homogeneously, relatively large skin areas. It is therefore particularly suitable for care to be carried out on an ad hoc basis, especially over a short period of time.

Moreover, because the hydrogels form a very aqueous medium, relatively little concentrated in salts with respect to the skin, the diffusion of the active ingredients in contact with the skin occurs quite easily by osmosis phenomenon.

The use of hydrogels therefore has the advantage of treating the skin while moisturizing, which is particularly advantageous in cosmetic facial care, including anti-aging care.

In doing so, the use of hydrogels also has interesting prospects in the medical field, particularly in the context of interventions with people whose skin has been burned, skinned or grafted, in particular in the context of a medicine. emergency.

However, currently available hydrogels have certain disadvantages that limit their use. A first disadvantage of conventional hydrogels lies in their fragility.

In terms of its chemical structure, a hydrogel is generally obtained by introducing gelling agents into the composition of active ingredients that it is desired to formulate. These gelling agents must be dermatologically neutral and not very concentrated in order to allow free circulation of the active ingredients of the hydrogel to the skin. In addition, the gelling complex must be compatible with the active ingredients that it is desired to formulate with the hydrogel. Hydrogels produced according to this principle are for example described in the international application WO 2008/072817, where agar, cellulose or alginates are used as gelling agents. Such hydrogels are difficult to handle and it is then necessary to use additives other than gelling agents, such as, for example, silk fiber proteins, to reinforce the hydrogel in its structure. In practice, hydrogels of this type have a thickness greater than 2 mm, which makes them too rigid to ensure optimal adhesion to the skin.

To overcome the fragility of conventional hydrogels, it is proposed in the prior art, hydrogels formed of several layers. International application WO 2001/78678 describes, for example, a device for forming a patch consisting of a hydrophilic rigid layer covered with a thin layer of hydrogel comprising active principles. Such a patch thus has two faces, only one of which, the one covered with hydrogel, is intended to be placed in contact with the skin.

The application US 2010/0055161 describes another type of device in which a hydrogel comprising active ingredients is formed on a peelable rigid support, which is removed at the time of applying the hydrogel. Such a device is formed of at least three layers, a first consisting of the hydrogel containing the active ingredients, a second consisting of an adhesive intermediate layer not comprising active ingredients, and the third semi-rigid, peelable formed for example a cardboard sheet. This type of device has the same disadvantage as the previous one because the hydrogel has a place and a back with a single face to be applied to the skin. Such a device makes the production and use of the hydrogel more complex.

Another disadvantage of hydrogels is their preservation. Due to the fact that they contain a large proportion of water, hydrogels are a particularly favorable medium for the development of microorganisms. In addition, they can deteriorate rapidly due to a change in their water content, and are subject to desiccation. It can then result, a demixing of the constituents of the hydrogel and leakage of the active ingredients.

Microbiologically, it is essential to be able to produce hydrogels under strict hygienic conditions, that is to say in a clean room with the minimum of human intervention.

Due to regulatory requirements in terms of hygiene and technical constraints related to the manufacture of hydrogels, the masks and patches described in the prior art could not be effectively marketed. Indeed, these hydrogels are generally layered on a unrolled support, then cut with a punch in the thickness of the layer to take the final form in which they will be packaged. This mode of production is not favorable to a strict hygiene of the products intended for the cosmetic or pharmaceutical care.

Surprisingly, the Applicant has developed a stable hydrogel composition based on a gelling and thickening complex comprising carrageenan, glucommanane and galactomannan.

This particular hydrogel composition has enabled it to obtain a thin, dermatologically neutral hydrogel with a structure sufficiently strong to be easily applied to the skin with optimal adhesion.

In addition to the fact that the hydrogel is obtained by a negative heat shock, the applicant has managed to produce this hydrogel under conditions of strict hygiene. The method consists in directly casting the hydrogel composition in its thermoformed packaging container, inducing the formation of the hydrogel by negative heat shock, and pouring a concentrated composition of the active ingredients onto the hydrogel, once this formed, before permanently sealing the package containing it.

Advantageously, the active ingredient composition is introduced into the hydrogel in concentrated liquid form, which makes it possible, in particular, to produce hydrogels comprising different active ingredients, starting from the same initial hydrogel composition.

Hydrogels produced and packaged in this way can be stored for more than 24 months at room temperature in the presence of a preservative system.

Other advantages of the hydrogel composition and the process according to the invention are detailed below.

FIG. 1 schematically illustrates steps A to E of the process used to produce and condition the hydrogel, of small thickness, according to the invention, with its active ingredient composition. FIG. 2 illustrates the implementation of the method according to the invention.

Figure 3 illustrates the use that can be made of a hydrogel mask according to the present invention. The present invention therefore relates to a particular hydrogel comprising a gelling and thickening complex based on carrageenan, glucomannan and galactomannan.

The inventors have been able to determine that this gelling complex makes it possible to obtain a thin hydrogel having favorable mechanical properties, in particular a good resistance to tearing, while not being too rigid. Moreover, the hydrogel thus formed has good absorption and diffusion properties of the active ingredients, as is illustrated below.

The inventors have been able to determine that the gelling and thickening complex of the hydrogel composition according to the invention optimally comprises between 0.2 and 2% carrageenan by hydrated weight of the hydrogel composition, between 0.2 and 2% glucommanane by hydrated weight of said composition, and between 0.2 and 2% of galactomannan by hydrated weight of said composition.

The use of galactomannan in the form of locust bean gum (natural extract of seeds of Ceratonia siliqua) has proved particularly favorable for obtaining hydrogels having the desired properties.

The thickening and gelling system implemented by the applicant therefore forms a very satisfactory compromise for the manufacture of patches or masks intended to be applied to the skin, hereinafter referred to as patches or hydrogel masks.

The hydrogel composition according to the invention generally comprises between 0.1 and 0.5% of potassium citrate. Potassium citrate advantageously participates in the implementation of the gelling complex and accelerates the formation of the hydrogel.

The hydrogel composition according to the invention generally further comprises between 1 and 5%, preferably between 1 and 3%, more preferably between 2 and 3% glycerol by hydrated weight of said composition. Glycerol or glycerin, hydrophilic molecule, is useful for its moisturizing effect, well known to those skilled in the art, which is added to that of the hydrogel itself.

A preferred hydrogel composition according to the invention thus comprises the following components (% hydrated weight of the composition):

Glycerol: 1 to 5%

Locust bean gum: 0.2 to 1, 6%

Carrageenan: 0.2 to 1%

Glucomannan: 0.2 to 1%

Potassium citrate: 0.1 to 0.5% Citric acid: 0.01 to 0.05%

Purified water: qsp.

By hydrogel is meant a gelled composition generally comprising between 85% and 97%, preferably between 90 and 97%, and more preferably between 90 and 95% by weight water hydrated of said composition.

According to the invention, the hydrogel is obtained from the composition comprising the thickening and gelling system (hydrogel composition) by a negative thermal shock, that is to say by a sudden cooling of the composition making it pass from the liquid or semi-liquid state to the solid state hydrogel.

In general, the negative thermal shock corresponds to a temperature drop of the composition of at least 20 ° C. to 0 ° C. in less than 20 seconds, preferably in less than 10 seconds and more preferably in less than 8 seconds. This cooling is generally obtained by ventilation of air at a negative temperature. Advantageously, the negative temperature amplitude is greater than 20 ° C, preferably greater than 30 ° C, and more preferably greater than 40 ° C.

The subject of the invention is also the process for producing and conditioning industrially the hydrogels according to the invention.

This method is characterized in that it comprises one or more of the following steps:

i) preparing a hydrogel composition comprising a gelling and thickening complex, as described above;

ii) pouring said hydrogel composition in a liquid or semi-liquid state into a molded container so as to form at the bottom of said container a layer having an average thickness of between 0.2 and 1.2 mm, preferably between 0.4 and 1 mm, more preferably between 0.5 and 0.8 mm; iii) subjecting said composition in its molded container to a negative thermal shock so that said hydrogel composition gels in contact with the wall of the molded container; iv) pouring on the hydrogel formed in step iii) in said molded container, a liquid composition comprising at least one cosmetic or pharmaceutical active ingredient, preferably in concentrated form;

v) sealing said container containing the hydrogel and the active ingredient composition, preferably by heat-sealing;

It will be noted that, according to the invention, the hydrogel is preferably formed in the absence of active principles, and that these are added, once the gelled hydrogel, in the form of a liquid composition comprising said active ingredients.

A cosmetic active ingredient composition may comprise, for example, one of the following active ingredients: papain, aloe vera, extracts of Glycyrrhiza or Scutellaria baicalensis. It can also include as an active ingredient an essential oil.

In general, this liquid composition is a concentrate of active ingredients, that is to say that the active ingredients are found there at least 5 times more concentrated than in the hydrogel obtained, once the active ingredients have diffused to inside said hydrogel.

Preferably, the active ingredients are at least 10 times more concentrated, and even more preferably 20 times more concentrated in active ingredients than the hydrogel obtained at the end of step iv) of the process.

Thus, the composition comprising at least one cosmetic or pharmaceutical active ingredient, brought into contact with the hydrogel in step iv) of the process, generally represents less than 20%, preferably less than 10% and more preferably less than 5% the volume of the hydrogel composition initially used to form the hydrogel.

Due to the properties of the hydrogel according to the invention, the composition comprising the active ingredients is rapidly absorbed and diffused homogeneously in the hydrogel.

Advantageously, the volume of the composition comprising concentrated active ingredients is adjusted so that said composition impregnates the hydrogel in its entirety. Preferably, the volume is adjusted so that the hydrogel reaches a state of saturation, so that a The residual volume of said composition remains in the liquid state in the molded container serving as a hydrogel package.

This residual volume prevents the hydrogel from drying inside the sealed container.

Moreover, the inventors have found that when the residual liquid volume was too great inside the sealed package, a second negative heat shock, once the sealed package, allowed to resorb the volume inside the sealed package. hydrogel by absorption.

At the industrial level, the fact of adding the active ingredients in the hydrogel after its formation, in the form of a concentrated liquid composition, is advantageous because it allows, with a single production line, to be able to produce hydrogels, in which different active ingredient compositions are included. It suffices for this to provide several tanks, in parallel, each containing a composition comprising different active ingredients.

The molded container used to produce and condition the hydrogel according to the invention is preferably thermoformed. It is advantageously tinted so that it protects the hydrogel from the effects of light (yellowing, deterioration of mechanical properties) related, especially to UV rays.

The method according to the invention has, moreover, the advantage of being able to be performed in a clean room in an automated or semi-automated manner. It solves the problem of the industrialization of the hydrogels of the prior art, the mechanical properties of which did not make it possible to carry out such conditioning.

By performing these steps, the applicant has indeed managed to produce repetitively, and in a manner, hydrogels comprising different types of pharmaceutical or cosmetic active ingredients. These hydrogels have successfully undergone anti-microbial preservation tests (Challenge test and NFT 75-611 eye safety test) showing that they meet European regulatory requirements for cosmetic products. The hydrogel obtained according to this process is generally of average thickness between 0.2 and 1.2 mm, preferably less than 1 mm, more preferably between 0.4 and 0.8 mm.

In its packaged form, the hydrogel according to the invention is preferably contained in a molded container hermetically sealed and loaded with a composition comprising at least one cosmetic or pharmaceutical active ingredient.

The hydrogel according to the invention preferably takes the form of a mask or a patch that is useful for carrying out medical or cosmetic care on the skin, as illustrated in the examples.

The present patent application also relates to a pharmaceutical or cosmetic kit consisting of or comprising the hydrogel prepared and packaged according to the method described above.

This kit is more particularly characterized in that it comprises a molded container, preferably hermetically sealed, containing a hydrogel according to the invention, and a liquid composition comprising active pharmaceutical or cosmetic ingredients. Said active ingredients are preferably present in this liquid composition in concentrated form, as previously defined.

By way of example, a hydrogel mask with anti-aging effects may include a liquid composition comprising the following active ingredients (percentages expressed by weight of the hydrated hydrogel):

between 1 and 5% of collagen hydrolyzate;

0.3 to 5% of oat glucan; and

between 0.2 and 1% of hyaluronic acid.

A hydrogel mask for the treatment of acne can include an active ingredient composition comprising green tea extracts.

The invention also aims at a cosmetic process, more particularly a skincare, characterized in that a hydrogel obtained according to the invention is applied to the skin, preferably the face. The invention also aims at a method of treating the skin, characterized in that it implements a hydrogel as previously described. The examples which follow are intended to complete the description without limiting it.

Examples of realization

1 / Preparation of a hvdroael mask

The various steps 1 to 5 below correspond to those illustrated A to E in FIG.

Step 1: Preparation of the hydrogel composition

In a clean room, the ingredients forming the hydrogel composition are mixed in a clean tank in the proportions indicated in Table 1 below, taking care to use purified water.

Table 1

Hydrogel composition

Glycerol 5.0%

Galactomannan 1.6%

(carob gum)

Carrageenan 1.0%

Glucomannan 0.8%

0.5% potassium citrate

Citric acid 0.05%

Conservative system 0.05%

Purified water 91% Water represents 91% of the final hydrated weight of the composition. The mixture is heated to 80 to 85 ° C, and the composition is allowed to cool to about 40 ° C.

Step 2: Pouring the hydrogel composition

The hydrogel composition is cast at room temperature in a thermoformed container, preferably made of medical grade PVC tinted anti-UV. These thermoformed containers form the base of the package in which the hydrogel mask is then packaged. They have a depth of less than cm for a rectangular surface of about 20 cm x 15 cm. The bottom of the container is horizontal and adopts the shape of a flat face. It has positive relief spaces in the mouth, nose and eyes.

The filling of the bottom of this thermoformed container is carried out using a pump and a metering device, directly into the thermoformed packaging container.

A volume of about 60 ml of the hydrogel composition is poured into the bottom of the thermoformed container to form a homogeneous layer with a thickness of about 0.5 mm. The latter is distributed evenly around the reliefs of the container reproducing the shape of the eyes, nose and mouth.

Step 3: Negative thermal shock

The container loaded with the hydrogel composition is then translated horizontally on the conveyor belt and passes through a cooling tunnel, in which cold air is drawn at a negative temperature ("-4 ° C). The passage in the refrigerant tunnel takes about 10 seconds.

At the outlet of the cooling tunnel, the composition which has suddenly cooled, gels and forms a hydrogel which follows the wall of the molded container, having the shape of a mask.

Step 4: Filling the hydrogel mask with a composition of concentrated cosmetic active ingredients A liquid cosmetic composition is obtained by mixing the ingredients in the proportions indicated in Table 2 below, in a second clean tank.

Table 2:

Composition of cosmetic active ingredients

This composition aims to moisturize the skin and reduce wrinkles and fine lines as part of an anti-aging care.

This composition is prepared at ambient temperature (<45 ° C.). Using a pump and a dispenser, a volume of 5 ml of this concentrated active ingredient composition is deposited on the hydrogel in the packaging container. Very quickly, the cosmetic composition is found completely absorbed by the hydrogel.

It will be noted that with a single production line, it is possible to provide different concentrates of active ingredients prepared in different tanks, in order to produce hydrogels having a different purpose.

Step 5: Heat sealing the container

Still inside the white room and shortly after the active composition has been poured onto the hydrogel, the thermoformed container containing the hydrogel mask is sealed by heat sealing. The film The lid is thermo-welded at the upper edge of the PVC packaging container around the entire circumference of the mask, and at the top of the reliefs forming the eyes, nose and mouth. The container thus being sealed and the hydrogel mask being impregnated with the active ingredient composition, it can be preserved, especially in the presence of a suitable preservative system (eg propytparaben, methylparaben and methylisothiazolinone), without drying out nor corrupt, for more than 24 months. 21 Using the hydrogel mask

The hydrogel mask produced and packaged in Example 1 above, was removed from its individual package by removing the seal. After cleaning the skin, it is positioned on the face of the person wishing to make an anti-aging treatment.

To ensure a good contact of the hydrogel with the surface of the skin, the person applies the mask so that it perfectly matches the shape of his face.

The mask is left in place for about 20 minutes, allowing the active ingredients in the hydrogel to penetrate the skin (upper layers of the stratum corneum).

When the mask is removed, the person removes the excess liquid on the surface of his skin using a tissue paper.

3 / Hydrogel mask efficacy test

Objectives of the tests

The objective of this study was to evaluate the effects on the skin relief of the product "Collagena Crystalline Mask" (commercial name given to the mask produced in Example 1 above) after a single application according to Example 2 and after 28 days of use, as well as the subjective appreciation of its organoleptic characteristics and its effectiveness after 28 days of use. Study of the variations of the parameters of the cutaneous relief

A study of the variations of the parameters of the cutaneous relief (average roughness Ra, median relief R3z, maximum amplitude Rt, average relief Rz,) using the 3D PRIMOS® Compact system (Phaseshift Rapid In vivo Measurement Of Skin - GF Messtechnik GmbH - 14513 BERLIN - Germany) was performed directly in vivo.

This technique consists of calculating a phase image from interference fringe projection images. This image makes it possible to go back to the altitude of each point.

The acquisition software then makes it possible to obtain 2D measurements and

3D, and determine the parameters of the cutaneous relief on 32 profiles distributed in star on the zone of interest. An automatic repositioning system allows precise re-identification of the measurement area.

The parameters used on each profile (the analysis focuses on the average of the 32 profiles) were as follows:

- Ra: average roughness (in pm).

Average roughness is defined as the ratio of the integrated area around the average value over the length of the profile. A decrease in Ra reflects a smoothing effect.

- R3z: the median relief (in pm).

The median relief value is the average of the five maxima of the median relief (vertical distance from the third highest peak and the third deepest hollow). A decrease in R3z reflects a tightening effect after a standardized application of a product and an anti-wrinkle effect during prolonged use.

- Rz: the average relief (in pm).

The average relief is the average value of all maxima (between peak and trough) over the length of the profile. A decrease in Rz reflects a tightening effect after a standardized application of a product and an anti-wrinkle effect during prolonged use.

- Rt: the amplitude (in pm): it is about the average value of the five largest maxima (between peak and hollow) on the length of the profile. A decrease of Rt translates a tightening effect after a standardized application of a product and an anti-wrinkle effect during prolonged use.

The results obtained have been reported in Table 3 below:

Table 3

Variation of the parameters of the cutaneous relief 5 minutes after a standardized single application

in comparison to the initial state

It can be seen from Table 3 that 5 minutes after a standardized single application, the product "Collagena Crystalline Mask" induced:

• a significant decrease in average roughness (Ra) of -4.1 pm on average, or -13%.

A smoothing effect was observed in 86% of the volunteers.

• a significant decrease in the median relief (R3z) of -7.3 pm on average, ie -0%.

• a significant decrease in the amplitude of the relief (Rt) of -27.6 pm on average, ie -9%.

• a significant decrease in average relief (Rz) of -20.8 pm on average, ie -12%.

A tightening / lifting effect was observed in 68 to 82% of the volunteers. Analysis of the answers given by the volunteers to the subjective evaluation questionnaire.

A subjective evaluation questionnaire, prepared by the clinical trial center, was completed by 22 volunteers at the end of the study in order to subjectively evaluate the characteristics of the studied product, as well as its overall effectiveness.

The synthesis of volunteers' responses is presented in Tables 4, 5 and 6 below.

For greater clarity, the percentages have been rounded to one unit. The sum of the percentages can therefore be different from 100%. In this study (n = 22), a volunteer is represented by 4.5%.

Table 4

Overall appreciation and organoleptic characteristics of the product

Table 5

Immediate effectiveness of the product

Sensation of freshness 86%

Moisturizing effect sensation 95%

Feeling of tensor / lift effect after application 86% Table 6

Efficacy of the product after 28 days

In the experimental conditions selected, the product "Mask

Crystaie de Collagena "induced a smoothing and tensing effect immediately after a single standardized application.

In addition, it has globally satisfied all volunteers for:

- its organoleptic characteristics: pleasant appearance, texture and fragrance.

- its immediate effectiveness: feeling of freshness, moisturizing effect and lifting / lifting effect.

- its effectiveness after 28 days of use: hydrated skin, soft, supple, luminous, younger, relaxing / de-stressing effect and relaxing sensation.

Claims

1. A hydrogel composition for application to the skin characterized by comprising a gelling and thickening complex comprising carrageenan, glucomannan and galactomannan.

2. A hydrogel composition according to the preceding claim, characterized in that the galactomannan is present in the form of locust bean gum.

3. A hydrogel composition according to one of the preceding claims, characterized in that said gelling and thickening complex comprises between 0.2 and 2% carrageenan by hydrated weight of said composition, between 0.2 and 2% glucommanane. by hydrated weight of said composition, and between 0.2 and 2% of galactomannan by hydrated weight of said composition.

4. A hydrogel composition according to one of the preceding claims, characterized in that it comprises, in addition, between 0.1 and 1% of potassium citrate by hydrated weight of said composition.

5. A hydrogel composition according to one of the preceding claims, characterized in that ele further comprises between 1 and 5% glycerol by hydrated weight of said composition.

6. A process for preparing and conditioning a hydrogel intended to be applied to the skin, characterized in that it comprises the following steps:

i) preparing a hydrogel composition according to one of claims 1 to 5; ii) pouring said hydrogel composition in a liquid or semi-liquid state into a molded container to form a layer having an average thickness of between 0.2 and 1.2 mm, preferably between 0.4 and 1 mm at the bottom of said container;

iii) subjecting said composition in its molded container, to a negative thermal shock so that said hydrogel composition gels in contact with the wall of the molded container, iv) poured on the hydrogel formed in step iii ) in said molded container, a liquid composition comprising at least one cosmetic or pharmaceutical active ingredient, preferably in concentrated form;

v) hermetically sealing said container containing the hydrogel and the active ingredient composition.

7. Method according to claim 6, characterized in that the composition comprising at least one cosmetic or pharmaceutical active ingredient poured in step iv) is concentrated and represents less than 10% of the volume of the hydrogel composition.

8. Method according to one of claims 6 and 7, characterized in that the composition of the active cosmetic ingredient comprises between 1 and 5% of collagen hydrolyzate, between 0.3 and 5% of oat glucan and between 0 , 2 and 1% hyaluronic acid.

9. Method according to one of claims 6 to 8, characterized in that the cosmetic active ingredient composition comprises at least one of the following active ingredients: papain, aloe vera, extracts of Glycyrrhiza or Scutellaria baicalensis.

10. Method according to one of claims 6 to 9, characterized in that the cosmetic active ingredient composition comprises a perfume.

11. Method according to one of claims 6 to 10, characterized in that the molded container is hermetically sealed in step v) by heat sealing.

12. Pharmaceutical or cosmetic kit obtainable according to the method of one of claims 1 to 6, characterized in that it comprises a hydrogen! of an average thickness of between 0.2 and 1.2 mm, preferably less than 1 mm, said hydrogel being loaded with a composition comprising at least one cosmetic or pharmaceutical active ingredient, and said hydrogel being contained in a molded container hermetically sealed.

13. Pharmaceutical or cosmetic kit according to claim 12, characterized in that said hydrogel is in the form of a mask.

14. Pharmaceutical or cosmetic kit according to claim 12, characterized in that said hydrogel is in the form of a patch.

15. Cosmetic treatment, characterized in that is applied to the skin, preferably the face, a hydrogel formed of a hydrogel composition according to any one of claims 1 to 5.

16. Cosmetic treatment, characterized in that a hydrogel obtained and packaged according to the method of any one of Claims 6 to 11 is applied to the skin, preferably the face.