Emulsions stabilised by amphiphilic composite particles

1. An emulsion comprising, in a physiologically acceptable medium, at least composite particles comprising:

a core comprising at least organic or inorganic particles A;

said core being covered, discontinuously, with an envelope comprising at least organic or inorganic particles B having a mean size of from 0.01 to 100 μm;

said particles A and B having different polarities and being present in an emulsion stabilizing effective,

wherein said emulsion is an oil-in-water emulsion comprising an oil phase dispersed in an aqueous phase, wherein said composite particles are dispersed in said aqueous phase, and wherein the oil-in-water emulsion does not comprise an emulsifying surfactant.

2. The emulsion according to claim 1 , wherein the particles A and B have a difference in polarity

Δ E=E T (30) A−E T (30) B

of greater than 2.

3. The emulsion according to claim 1 , wherein a weight ratio of the core to the envelope of the composite particles is from 70/30 to 99.9/0.1.

4. The emulsion according to claim 1 , wherein the material constituting particles A of the core of the composite particles is selected from the group consisting of:

(i) crosslinked or non-crosslinked poly(meth)acrylate polymers;

(ii) crosslinked organopolysiloxane elastomers;

(iii) polysaccharides that are natural or of natural origin;

(iv) polyamide particles;

(v) particles of copolymer of styrene and of (meth)acrylic acid or a (C1-C20)alkyl ester thereof;

(vi) polymethylsilsesquioxanes;

(vii) inorganic particles; and

(viii) mixtures thereof.

5. The emulsion according to claim 1 , wherein the material constituting particles B of the envelope of the composite particles is selected from the group consisting of:

(i) polymethylsilsesquioxanes;

(ii) crosslinked or non-crosslinked poly(meth)acrylate polymers;

(iii) fumed silicas;

(iv) hydroxyapatites;

(v) coated or uncoated metal oxide particles;

(vi) alumina; and

(vii) mixtures thereof.

6. The emulsion according to claim 1 , wherein the composite particles are selected from the group consisting of:

composite particles whose core is formed from crosslinked polymethyl methacrylate and whose envelope is formed from hydroxyapatite;

composite particles whose core is formed from crosslinked polymethyl methacrylate and whose envelope is formed from fumed silica;

composite particles whose core is formed from organopolysiloxane elastomer and whose envelope is formed from fumed silica;

composite particles whose core is formed from crosslinked polymethyl methacrylate and whose envelope is formed from polymethylsilsesquioxane;

composite particles whose core is formed from a polysaccharide, and whose envelope is formed from polymethyl methacrylate;

composite particles whose core is formed from polymethyl methacrylate and whose envelope is formed from fumed silica;

composite particles whose core is formed from polymethylsilsesquioxane and whose envelope is formed from fumed silica; and

composite particles whose core is formed from polymethyl methacrylate and whose envelope is formed from titanium oxide.

7. The emulsion according to claim 1 , wherein the composite particles are composite particles whose core is formed from a polysaccharide, and whose envelope is formed from polymethyl methacrylate.

8. The emulsion according to claim 7 , wherein the polysaccharide has:

a wet point for oil of at least 25 ml/100 g, and

a wet point for water of at least 50 mg/100 g, and a ratio of the wet point for water/wet point for oil of less than or equal to 5.

9. The emulsion according to claim 7 , wherein the polysaccharide is a porous cellulose or a type II cellulose.

10. The emulsion according to claim 1 , wherein the composite particles are obtained by chemical mechanofusion.

11. The emulsion according to claim 1 , wherein the composite particles are present in concentrations ranging from 0.1% to 10% by weight relative to the total weight of the emulsion.

12. A process for preparing the emulsion according to claim 1 , comprising:

a) dispersion, at room temperature (20-25° C.), of the composite particles comprising a core comprising at least organic or inorganic particles A;

said core being covered, discontinuously, with an envelope comprising at least organic or inorganic particles B;

said particles A and B having different polarities, with stirring; and

b) introduction of the oily phase into the aqueous phase with slow stirring; and

c) optional addition of other ingredients; and

d) mixing with stirring until the emulsion is formed and a macroscopically homogeneous mixture is obtained.

13. A cosmetic process for treating a keratin material, comprising:

applying to the keratin material an emulsion according to claim 1 .

14. The emulsion according to claim 1 , wherein the materials A and B have a difference in polarity

Δ E=E T (30) A−E T (30) B

of greater than 5.

15. The emulsion according to claim 1 , wherein the composite particles have a mean size ranging from 0.5 to 15 μm and a weight ratio of the core to the envelope of the composite particles is from 80/20 to 99/1.

16. The emulsion according to claim 1 , wherein the composite particles have a mean size ranging from 1 to 10 μm and a weight ratio of the core to the envelope of the composite particles is from 90/10 to 99/1.

17. The emulsion according to claim 1 , wherein 10% to 90% of the surface of the core is surrounded with an envelope comprising at least organic or inorganic particles B.

18. The emulsion according to claim 1 , wherein the organic or inorganic particles B have a mean size of from 0.05 to 50 μm.

19. The emulsion according to claim 1 , wherein particles A are organic.