FR3082733A1 - PICKERING-TYPE EMULSIONS - Google Patents

Abstract

The present invention relates to compositions, in particular cosmetic or dermatological, preferably for topical application, of the “Pickering” type. The invention also relates to a calcined synthetic phyllosilicate, which is particularly useful in “Pickering” type compositions for improving its stability.

Description

Description

Title of the invention: Pickering type emulsions

Technical Field [0001] The present invention relates to compositions, in particular cosmetic or dermatological, preferably for topical application, of the “Pickering” type. The invention also relates to a calcined synthetic phyllosilicate, and also relates to a synthetic phyllosilicate having a specific surface greater than or equal to 100 m ² / g, which are particularly useful in “Pickering” type compositions to improve its stability.

STATE OF THE ART [0003] In cosmetics, oil in water or water in oil emulsions are frequently formulated. These emulsions notably have interesting sensory properties. However, these are naturally not stable and are generally stabilized by surfactants; however surfactants have drawbacks.

Indeed, the surfactants can have a negative impact on the powdery nature of the deposit, much appreciated by consumers. They can also limit the use of other ingredients, such as aluminum salts. They can also produce a sticky, slippery or soaping effect, effects which can be annoying when the product is used by the consumer. In addition, many surfactants are toxic to the environment.

[0005] Thus, it has been proposed to use particles at the interfaces of these emulsions, in order to manufacture “Pickering” type emulsions. A “Pickering” type emulsion is an emulsion comprising a continuous phase and a phase dispersed in said continuous phase; said phases being immiscible, and said emulsion being stabilized by solid particles adsorbed at the interface of the two immiscible phases and this without the need to use emulsifying surfactants.

Application ER3028754 notably discloses Pickering type emulsions comprising at least one synthetic phyllosilicate with molecular formula Mg ₃ Si ₄ Oio (OH) ₂ ; at least one aqueous phase; and at least one oily phase.

However, the inventors have demonstrated that the use of synthetic talc as disclosed in application LR3028754 did not allow all the emulsions to be stabilized.

There therefore remains a need for stable emulsions and compositions which are respectful of the skin and / or of the nails and as such having reduced amounts of surfactants or even advantageously devoid of surfactants, stable whatever the composition of the emulsion. .

SUMMARY [0010] Thus the subject of the invention is an emulsion of the Pickering type, in particular cosmetic or dermatological, comprising: an aqueous phase; an oily phase; and synthetic phyllosilicate particles, said particles being surface modified particles. The invention also relates to the use of synthetic surface-modified phyllosilicate particles as an emulsion stabilizing agent.

In fact, the inventors have surprisingly found that the emulsions according to the invention have excellent stability, regardless of the nature of the emulsion (that is to say, whether it is direct or indirect , or that it contains more or less of aqueous phase compared to the fatty phase or for example that it has a more or less polar fatty phase). For example, the emulsions according to the invention exhibit good stability if they comprise between 1 and 90% of fatty phase. For example, the emulsion according to the invention has good stability for a composition comprising more than 20% of fatty phase.

By phyllosilicate is meant in particular talc, kaolin, bentonite, and halloysite. For example, the synthetic phyllosilicate particles are synthetic talc particles.

For example, the emulsion according to the invention comprises between 0.01 and 5% by weight of surface modified synthetic phyllosilicate particles, relative to the total weight of the emulsion. For example, it comprises between 0.03 and 3% or between 0.03 and 1% by weight of surface-modified synthetic phyllosilicate particles, relative to the total weight of the emulsion.

For example, it comprises between 0.1 and 1% by weight of surface modified synthetic phyllosilicate particles, relative to the total weight of the emulsion. For example, the emulsion according to the invention comprises between 0.03 and 0.8%, between 0.05 and 0.5%, alternatively between 0.1 and 0.3% by weight of synthetic phyllosilicate particles modified in surface, relative to the total weight of the emulsion. By% by weight of surface-modified synthetic phyllosilicate particles is meant the percentage by weight of surface-modified synthetic phyllosilicate particles taken as dry matter, relative to the total weight of the emulsion.

According to one embodiment of the invention, the surface modified synthetic phyllosilicate particles are particles coated with a treatment agent.

For example, the surface modified synthetic phyllosilicate particles comprise between 0.1 and 10% by weight of treatment agent, based on the weight of the synthetic phyllosilicate, for example between 0.2 and 5% by weight processing agent.

For example, the treatment agent is a hydrophobic treatment agent or a hydrophilic treatment agent.

For example, the treatment agent is a hydrophobic treatment agent. For example, it is chosen from alkylsilanes, fluorosilanes, polysiloxanes, Γ isopropyl titanium triisostearate.

Alternatively, the treatment agent is a hydrophilic treatment agent. For example, it is chosen from cellulose, hydrophobic silanes, and sodium acetate, for example methoxy PEG 10 propyltrimethoxysilane or sodium acetate. For example, the treatment agent is sodium acetate.

According to another embodiment of the invention, the surface modified synthetic phyllosilicate particles are calcined phyllosilicate particles.

According to another embodiment of the invention, the surface modified synthetic phyllosilicate particles are synthetic phyllosilicate particles having a specific surface greater than or equal to 100 m ² / g, preferably greater than or equal to 300 m ² / g, for example, greater than 300 m ² / g and less than 1000 m ² / g.

According to one embodiment, the invention also relates to a Pickering type emulsion, in particular cosmetic, comprising:

- an aqueous phase;

- an oily phase; and synthetic talc particles, said particles being particles functionalized with a hydrophobic or hydrophilic treatment agent [0025] According to one of the preceding embodiments of the invention, the emulsion is of the oil-in-type water or water-in-oil type.

For example, said emulsion comprises less than 7% by weight of surfactant, for example comprises less than 3% by weight of surfactant, alternatively does not include a surfactant. For example, said emulsion comprises less than 1% by weight of surfactant; for example, it comprises less than 0.1% by weight of surfactant.

According to one embodiment of the invention, the emulsion is a cosmetic or dermatological composition and further comprises a physiologically acceptable medium.

The invention also relates to the use of synthetic phyllosilicate particles according to the invention as stabilizing agent for an emulsion as defined according to the invention.

The invention also relates to a cosmetic treatment process comprising the application to the skin and / or the nails of an emulsion according to the invention.

The invention also relates to a process for preparing surface-modified synthetic talc particles comprising mixing synthetic talc particles with a treatment agent as defined above in appropriate amounts in order to obtain synthetic talc particles surface modified as defined above.

The invention also relates to surface modified synthetic phyllosilicate particles, said particles being obtained by a calcination process.

In addition, the invention relates to synthetic talc particles modified on the surface, said particles being synthetic talc particles having a specific surface greater than or equal to 100 m ² / g.

The invention also relates to synthetic talc particles, said particles being particles functionalized by a hydrophobic or hydrophilic treatment agent.

The invention thus relates to a Pickering type emulsion, in particular cosmetic or dermatological, comprising: an aqueous phase; an oily phase; and synthetic phyllosilicate particles, said particles being surface modified particles.

The choice of the type of surface modified phyllosilicate is made by a person skilled in the art, which allows him to obtain the most stable emulsions over time.

For an indirect emulsion, he may choose for example a calcined synthetic phyllosilicate or a synthetic phyllosilicate coated with a hydrophobic treatment agent.

For a direct emulsion comprising a very apolar fatty phase (for example, parraffin, petrolatum, squalane, isohexadecane, or isododecane), it will choose for example a calcined synthetic phyllosilicate or a synthetic phyllosilicate coated with a hydrophobic treatment agent.

For a direct emulsion comprising a very polar fatty phase (for example, cetaryl alcohol, cetyl alcohol, stearyl alcohol, lanolin alcohol or caprylic / capric triglyceride), it will for example choose a synthetic phyllosilicate coated with a hydrophilic treatment agent.

Conversely, it seems that an unmodified synthetic talc on the surface makes it possible to stabilize only certain direct emulsions with oils of medium polarity (for example, vegetable oils such as almond oil, d oil). sweet almond, borage oil, macadamia oil, olive oil, coconut oil; or opropisopropyl myristate).

By synthetic phyllosilicate is meant in particular synthetic talc. Talc is especially understood to mean which has been synthesized using a synthetic synthesis method, for example by a method as described in patent applications.

WO2015159006 or W02008009799, the entire contents of which are incorporated herein by reference.

For example, synthetic talc is produced via a process for preparing a synthetic talc composition, in which a kerolite composition is subjected to an anhydrous heat treatment carried out at a pressure of less than 5 bars, for a period of time and with a treatment temperature above 300 ° C., chosen so as to obtain particles of thermally stable synthetic talc and of formula Si ₄ Mg ₃ O io (OH) ₂ .

Alternatively, the synthetic talc is obtained via a process for the preparation of synthetic phyllo mineral particles formed from chemical elements, called constituent chemical elements, in predetermined proportions, called stoichiometric proportions, said constituent chemical elements comprising at least one chosen chemical element. in the group formed from silicon and germanium, and at least one chemical element chosen from the group formed from divalent metals and trivalent metals, by a treatment, called solvothermal treatment, of a reaction medium comprising a liquid medium and containing said proportions stoichiometric of said chemical elements constituting said synthetic phyllomineral particles, said synthetic phyllomineral particles belonging to the group of non-swelling phyllosilicates, in which:

Said solvothermal treatment is carried out continuously at a pressure greater than 1 MPa and at a temperature between 100 ° C. and 600 ° C., the reaction medium is circulated continuously in a zone, called the solvothermal treatment zone, d a continuous reactor with a residence time of the reaction medium in said solvothermal treatment zone suitable for obtaining continuously, at the outlet of said solvothermal treatment zone, a suspension comprising said synthetic phyllomineral particles.

In particular, synthetic talc is characterized by an X-ray diffraction analysis of said talc particles leading to the production of a diffractogram having the following characteristic diffraction peaks:

- A peak located at 9.40-9.68 Â, corresponding to a plane (001);

- a peak located at 4.50-4.60,, corresponding to a plane (020);

- a peak located at 3.10-3.20 Å, corresponding to a plane (003);

- A peak located at 1.50-1.55 A, corresponding to a plane (060).

The composition according to the invention is an emulsion, that is to say that it comprises a fatty phase and an aqueous phase.

The aqueous phase comprises water, and optionally a water-soluble solvent such as, for example, ethylene glycol, propylene glycol, glycerin or 1,3-butylene glycol.

The aqueous phase in the case of an emulsion may be present in the composition in an amount ranging from 5 to 95%, for example from 30 to 90%, for example from 40 to 80% by weight relative to the weight total of said composition.

The fatty phase includes any liquid fatty substances, generally oils, or solids.

A liquid fatty phase comprises at least one oil.

Oil means any fatty substance in liquid form at room temperature and atmospheric pressure. They can be volatile or non-volatile.

By surface modified particles means any particle whose surface has been modified at the surface, by a process which has created modifications compared to the original particle. Thus, the particle can be coated; it can also be calcined; or again, any other process bringing about a modification of its surface, including its specific surface. Examples include processes such as a surface treatment process or a calcination process.

According to one embodiment of the invention, the surface modified synthetic phyllosilicate particles are particles coated with a treatment agent. By treatment agent is meant any product capable of coating all or part of the phyllosilicate particles in order to change their properties, in particular, capable of changing its affinity / dispersibility properties with water, or affinity / dispersibility with the fatty phase. Preferably means a treatment agent capable of modifying the lipophilicity of the phyllosilicate particles.

For example, the surface modified synthetic phyllosilicate particles comprise between 0.1 and 10% by weight of treatment agent, based on the weight of the synthetic phyllosilicate, for example between 0.2 and 5% by weight processing agent.

More particularly, we mean a hydrophobic treatment agent or a hydrophilic treatment agent.

By hydrophobic treatment agent is meant a treatment agent, which, when used in contact with synthetic phyllosilicate particles, makes the phyllosilicate particles more hydrophobic. For example, the hydrophobic treatment agent can be chosen from alkylsilanes, fluorosilanes, polysiloxanes, isopropyl titanium triisostearate and their mixtures.

By hydrophilic treatment agent is meant a treatment agent, which, when used in contact with synthetic phyllosilicate particles, makes the phyllosilicate particles more hydrophilic. For example, the hydrophilic treatment agent is chosen from cellulose, hydrophobic silanes, for example methoxy PEG 10 propyltrimethoxysilane or carboxyl methyl cellulose and sodium acetate.

The particles of synthetic phyllosilicate coated with a treatment agent can be prepared by mixing the synthetic phyllosilicate with the surface treatment agent in appropriate amounts, for example, in amounts suitable for obtaining phyllosilicate particles coated with a treatment agent comprising from 0.1 to 10% by weight of treatment agent, for example, from 0.1 to 1% by weight of treatment agent, relative to the weight of the synthetic phyllosilicate. The treatment agent can be provided as a solution or dispersion. The solvent or dispersant can be any liquid medium capable of dissolving or dispersing the treatment agent. If the treatment agent is soluble in water, the treatment agent can be supplied as an aqueous solution. Stirring can be useful for dissolving or dispersing the treatment agent in the liquid medium and can be continued for an appropriate period. The solution or dispersion obtained is then mixed with an appropriate amount of synthetic phyllosilicate particles. The mixing can be carried out in any suitable mixing device, for example a high speed agitator, for example capable of mixing at a speed of up to 5000 revolutions per minute, for example 10 000 revolutions per minute.

Alternatively, according to another embodiment of the invention, the synthetic phyllosilicate particles are particles functionalized with a hydrophobic or hydrophilic treatment agent.

The synthetic phyllosilicate particles functionalized with a treatment agent can be prepared according to the method described below.

It is indeed possible to functionalize the synthetic phyllosilicate particles with a hydrophobic or hydrophilic treatment agent which is essentially placed between the sheets of the synthetic phyllicosilicate particles.

For this, a possible synthesis route is to add the treatment agent to the reactor, before hydrothermal treatment. For example, the hydrophobic or hydrophilic treatment agent can be mixed beforehand with the reagent comprising a chemical element chosen from the group formed by silicon and germanium; or it can be mixed beforehand with the reagent comprising a chemical element chosen from the group formed by divalent metals and trivalent metals.

The synthesis process is then carried out as described above; as for example described in patent application WO2015159006.

According to another embodiment of the invention, the surface modified synthetic phyllosilicate particles are particles of calcined synthetic phyllosilicate.

By particles of calcined synthetic phyllosilicate is meant any particle of synthetic phyllosilicate having undergone a calcination process, this having led to at least partial or even total dehydroxylation of the particle of synthetic phyllosilicate. Dehydroxylation increases the hydrophobic character of synthetic talc. To form calcined synthetic phyllosilicate, the calcination temperature can be controlled so that the synthetic phyllosilicate undergoes an endothermic dehydration reaction, and the original synthetic phyllosilicate particles can be entirely or partially dehydroxylated.

The synthetic phyllosilicate can, for example, undergo dehydroxylation by calcination. It is a thermal treatment, usually in the presence of oxygen or air. Calcination changes the structure of the synthetic phyllosilicate from crystalline to amorphous. The degree to which the synthetic phyllosilicate undergoes its crystalline form depends on the amount of heat to which it is subjected. In general, the higher the temperature, the shorter the calcination time. In general, calcination is carried out at a temperature ranging from about 550 ° C to about 950 ° C (for example, ranging from about 650 ° C to about 900 ° C, for example, ranging from about 750 ° C to about 850 ° C) to produce calcined synthetic phyllosilicate particles.

For example, any oven, furnace, furnace, or any other heating appliance can be used for the calcination of synthetic phyllosilicate.

A typical method consists in heating the synthetic phyllosilicate in an oven, for example a conventional rotary oven.

The calcination process used can, for example, be a soak calcining, that is to say that the synthetic phyllosilicate is calcined during a period during which the chemistry of the mineral is gradually changed by the effect of heat. The calcination may for example last for a period of at least one minute, generally at least ten minutes, for example between 30 minutes and 5 hours or more. Known means capable of performing calcination by immersion include high temperature ovens, rotary ovens and vertical ovens.

The calcination process can for example be a "flash" calcination, in which the synthetic phyllosilicate is rapidly heated for a period of less than a second, for example, less than 0.5 seconds. Flash calcination can, for example, introduce the synthetic phyllosilicate into a stream of hot gas for a few seconds or a few tenths of a second. Flash calcination is the heating of a material at an extremely fast rate, almost instantly. The heating rate of a flash calciner can be of the order of 56,000 ° C per second or more, such as, for example, about 100,000 ° C to about 200,000 ° C per second. Synthetic phyllosilicate can, for example, be prepared by flash calcination in which the synthetic phyllosilicate is exposed to a temperature of 500 ° C for a period of time not exceeding 5 seconds. The synthetic phyllosilicate can, for example, be calcined at a temperature ranging from 550 ° C to 1200 ° C; for a short duration, on the order of a microsecond, the temperature can go up to 1500 ° C. The synthetic phyllosilicate can be calcined at a temperature ranging from 800 ° C to 1100 ° C; for example a temperature ranging from 900 ° C to 1050 ° C; for example a temperature ranging from 950 ° C to 1000 ° C. The synthetic phyllosilicate can, for example, be calcined for a period of less than 5 seconds; for example less than 1 second; for example less than 0.5 seconds; for example less than 0.1 seconds. The flash calcination of the synthetic phyllosilicate gives rise to relatively rapid dehydroxylation of the synthetic phyllosilicate.

Flash calcination can be carried out by injecting the synthetic phyllosilicate into a combustion chamber, or an oven, in which a vortex can be put in place, in order to remove the calcined synthetic phyllosilicate quickly from the combustion chamber. A suitable oven could for example be the oven described in WO 99/24360, its content being incorporated by reference in its entirety.

According to another embodiment of the invention, the surface modified synthetic phyllosilicate particles are synthetic phyllosilicate particles having a specific surface greater than or equal to 100 m ² / g, preferably greater than or equal to 300 m ² / g, for example, greater than 300 m ² / g and less than 1000 m ² / g, according to the B AND method.

For example, the synthetic phyllosilicate particles have an average particle size d ₅₀ (measured by sedigraph) less than or equal to 300 nm, for example between 0.1 nm and 300 nm.

The synthetic batch talc synthesis methods of the “batch” type as described for example in patent application WO2008009800, do not make it possible to obtain particles of synthetic phyllosilicate having a specific surface greater than or equal to 100 m ² / g or having an average particle size d ₅₀ (measured by sedigraph) less than or equal to 300nm.

The “continuous” type synthesis process described in application WO2015159006 also does not, as such, make it possible to reach these particles.

To obtain these particles, a possible synthesis route is to modify the reaction conditions during the hydrothermal treatment as described in application WO2015159006. Thus, a possible synthesis route comprises the step of a hydrothermal treatment, at a temperature between 200 and 600 ° C, in particular between 350 and 400 ° C, and at a pressure between 2MPa and 50 MPa, especially between 22MPa and 30 MPa, and with a residence time of less than 40 seconds, preferably less than 20 seconds.

Another possible synthetic route comprises the step of a hydrothermal treatment, at a temperature between 100 and 500 ° C, especially between 250 and 300 ° C, at a pressure between 2MPa and 50 MPa, especially between 22MPa and 30MPa, and with a residence time of less than 5 minutes.

The other steps of the synthesis process are as described above; as for example described in patent application WO2015159006.

Unless otherwise indicated, the particle sizes cited in the present application are measured in a manner well known to those skilled in the art, by sedimentation of the particles in an aqueous medium under a fully dispersed condition using a SediGraph III 5120 (Micrometrics Corporation Norcross, Georgia, USA (phone:

+ 17706623620; website: www.micromeritics.com), which will be cited by “Micromeritics Sedigraph 5120 unit” (standard method ISO 13317-3). Such a machine provides the measurements and the trace of the cumulative percentage, by weight, of particles having a size commonly called 'equivalent spherical diameter' (esd), or equivalent spherical diameter. The average particle size, or d ₅₀ , is the value, determined in this way, for which 50% by weight of the particles have an equivalent spherical diameter less than this d ₅₀ .

According to one of the previous embodiments of the invention, the emulsion is of the oil-in-water type or of the water-in-oil type.

By oil-in-water type emulsion is meant an oily phase dispersed in an aqueous phase, that is to say that the emulsion mainly comprises an aqueous phase. An oil-in-water type emulsion is also called a direct emulsion.

By water-in-oil type emulsion is meant an aqueous phase dispersed in an oily phase, that is to say that the emulsion mainly comprises an oily phase. A water-in-oil type emulsion is also called an indirect emulsion.

For example, said emulsion comprises less than 7% by weight of surfactant, for example comprises less than 3% by weight of surfactant, alternatively does not comprise a surfactant. For example, said emulsion comprises less than 1% by weight of surfactant; for example, it comprises less than 0.1% by weight of surfactant. By surfactant is meant an amphiphilic molecule, that is to say that it has two parts of different polarity, one lipophilic and nonpolar, the other hydrophilic and polar.

The invention also makes it possible to stabilize any type of emulsion, despite little or no surfactant present in the composition.

According to one embodiment of the invention, the emulsion is a cosmetic or dermatological composition and also comprises a physiologically acceptable medium.

By physiologically acceptable medium is meant a medium compatible with the skin and / or the nails. In particular, it will be an environment with no unpleasant appearance and does not generate an unacceptable effect for the user such as tingling or tightness.

The invention also relates to the use of synthetic phyllosilicate particles modified on the surface according to the invention as stabilizing agent for an emulsion as defined according to the invention.

The invention also relates to a cosmetic treatment process comprising the application to the skin and / or the nails of an emulsion according to the invention.

The emulsion according to the invention is particularly suitable for topical application.

The invention also relates to surface modified synthetic phyllosilicate particles, said particles being obtained by a calcination process.

In addition, the invention relates to particles of synthetic talc modified on the surface, said particles being particles of synthetic talc having a specific surface greater than or equal to 100 m ² / g.

The invention also relates to synthetic talc particles, said particles being particles functionalized with a hydrophobic or hydrophilic treatment agent.

Description of the embodiments Examples The examples which follow are intended to illustrate the invention and are in no way limiting.

Formula [Tables 1]

Phase INCI Name Trade name % AT Aqua qs 100 Glycerin - 5 phenoxyethanol Euxyl PE9010 (Shülke & Mayr GmbH) 0.75 B Synthetic talc - 10% (1% dry material) VS Cocoglycerides Myritol 331 (BASE) 30

Protocol [0101] - In the bowl of the speedmixer, we weigh A and homogenize using the speedmixer at 2500rpm for 30sec.

- Add B to A and homogenize using the speedmixer at 3000rpm for 1min.

- Add C to A and homogenize using the speedmixer at 3000rpm for 1min.

[0102] Stability [0103] [Tables!]

Caractérisatio not Settings tO at 25 ° C t24hà 25 ° C time to 25 ° C With synthetic Talc not modified on the surface (comparative example) Appearance, color, odor Macroscopic NO CONFORM E NO CONFORM E NO CONFORM E centrifugation 60min to 2000rpm at 25 ° C NO CONFORM E

claims [Claim 1] Pickering type emulsion, in particular cosmetic or dermatological, comprising: - an aqueous phase; - an oily phase; and - synthetic talc particles, said particles being surface modified particles. [Claim 2] The emulsion of claim 1, wherein the surface-modified synthetic talc particles are particles coated with a treating agent. [Claim 3] Emulsion according to Claim 2, in which the surface-modified synthetic talc particles comprise between 0.1 and 10% by weight of treatment agent, based on the weight of the synthetic talc, for example between 0.2 and 5% by weight of treatment agent. [Claim 4] Emulsion according to either of Claims 2 and 3, in which the treatment agent is a hydrophobic treatment agent or a hydrophilic treatment agent. [Claim 5] Emulsion according to Claim 4, in which the treatment agent is a hydrophobic treatment agent and is chosen from alkylsilanes, fluorosilanes, polysiloxanes, isopropyl titanium triisostearate. [Claim 6] Emulsion according to Claim 4, in which the treatment agent is a hydrophilic treatment agent and is chosen from cellulose, hydrophobic silanes and sodium acetate, for example methoxy PEG 10 propyltrimethoxysilane. [Claim 7] The emulsion of claim 1, wherein the surface-modified synthetic talc particles are talc calcine particles. [Claim 8] Emulsion according to Claim 1, in which the surface-modified synthetic talc particles are synthetic talc particles having a specific surface greater than or equal to 100 m ² / g. [Claim 9] Pickering type emulsion, in particular cosmetic, comprising: - an aqueous phase; - an oily phase; and synthetic talc particles, said particles being particles functionalized by a hydrophobic or hydrophilic treatment agent. [Claim 10] Emulsion according to one of the preceding claims, said emulsion being of the oil-in-water type or of the water-in-oil type.

Claims (1)

claims [Claim 1] Pickering type emulsion, in particular cosmetic or dermatological, comprising: - an aqueous phase; - an oily phase; and - synthetic talc particles, said particles being surface modified particles. [Claim 2] The emulsion of claim 1, wherein the surface-modified synthetic talc particles are particles coated with a treating agent. [Claim 3] Emulsion according to Claim 2, in which the surface-modified synthetic talc particles comprise between 0.1 and 10% by weight of treatment agent, based on the weight of the synthetic talc, for example between 0.2 and 5% by weight of treatment agent. [Claim 4] Emulsion according to either of Claims 2 and 3, in which the treatment agent is a hydrophobic treatment agent or a hydrophilic treatment agent. [Claim 5] Emulsion according to Claim 4, in which the treatment agent is a hydrophobic treatment agent and is chosen from alkylsilanes, fluorosilanes, polysiloxanes, isopropyl titanium triisostearate. [Claim 6] Emulsion according to Claim 4, in which the treatment agent is a hydrophilic treatment agent and is chosen from cellulose, hydrophobic silanes and sodium acetate, for example methoxy PEG 10 propyltrimethoxysilane. [Claim 7] The emulsion of claim 1, wherein the surface-modified synthetic talc particles are talc calcine particles. [Claim 8] Emulsion according to Claim 1, in which the surface-modified synthetic talc particles are synthetic talc particles having a specific surface greater than or equal to 100 m ² / g. [Claim 9] Pickering type emulsion, in particular cosmetic, comprising: - an aqueous phase; - an oily phase; and synthetic talc particles, said particles being particles functionalized by a hydrophobic or hydrophilic treatment agent. [Claim 10] Emulsion according to one of the preceding claims, said emulsion being of the oil-in-water type or of the water-in-oil type. [Claim 11] Emulsion according to one of the preceding claims, said emulsion comprising less than 7% by weight of surfactant, for example comprising less than 3% by weight of surfactant, alternatively not comprising substantially no surfactant. [Claim 12] Emulsion according to one of the preceding claims, said emulsion being a cosmetic or dermatological composition and further comprises a physiologically acceptable medium. [Claim 13] Use of surface-modified synthetic talc particles as defined in one of claims 1 to 8 or functionalized as defined in claim 9 as an emulsion stabilizing agent as defined in one of claims 1 to 12. [Claim 14] Cosmetic treatment process comprising the application to the skin and / or the nails of an emulsion according to one of claims 1 to 12. [Claim 15] Surface modified synthetic talc particles, said particles being obtained by a calcination process. [Claim 16] Surface modified synthetic talc particles, said particles being synthetic talc particles having a specific surface greater than or equal to 100 m ² / g. FRENCH REPUBLIC