COSMETIC COMPOSITION BASED ON JANUS PARTICLES

Abstract

A cosmetic composition comprising Janus particles, an aqueous phase and an organic phase uses Janus particles produced with a method which includes the preparation of hollow particles (1) having two non-continuous surfaces of a material with surface energy a, of which the external one (2) is accessible and the internal one (3) is inaccessible. The surface energy of the external surface (2) is thereby modified originating particles (11) with internal surface energy a and external surface energy 13. The modified particles (11) are then ground until particles are obtained constituted by small fragments (21) shaped as spherical caps with external surface (12) having modified energy and internal surface (13) having non-modified internal energy.

Claims

1-16. (canceled)

17. A cosmetic composition, comprising: Janus particles, wherein the Janus particles are constituted by concave fragments of hollow spherical particles with internal surface energy a and external surface energy B, an aqueous phase and an organic phase, and wherein the Janus particles are comprised between 0.01% by weight and 99.99% by weight and the sum of aqueous phase and organic phase is between 0.01% by weight and 99.99% by weight.

18. The cosmetic composition according to claim 17, wherein the aqueous phase is constituted by water and hydro-soluble and/or hydro-dispersible substances.

19. The cosmetic composition according to claim 17, wherein the organic phase is constituted by oils belonging to the triglyceride and/or ester and/or glyceryl ester class and/or silicones and/or any other oils acceptable for cosmetic use and respective mixtures thereof.

20. The cosmetic composition according to claim 17, wherein the organic phase contains one or more oils and oil-soluble and/or oil-dispersible substances.

21. The cosmetic composition according to claim 17, wherein the organic phase is comprised between 10% by weight and 90% by weight, the aqueous phase is comprised between 90% by weight and 10% by weight and the Janus particles are comprised between 20% by weight and 0.01% by weight, and wherein the aqueous phase is dispersed in the organic phase (water-in-oil/silicone emulsion) or vice versa (oil/silicone-in-water emulsion).

22. The cosmetic composition according to claim 17, wherein the organic phase is comprised between 0.01% by weight and 10% by weight, the aqueous phase is comprised between 10% by weight and 70% by weight and the Janus particles are comprised between 10% by weight and 90% by weight.

23. The cosmetic composition according to claim 17, wherein said concave fragments are obtained by grinding said hollow spherical particles.

24. The cosmetic composition according to claim 17, wherein said hollow spherical particles are shaped as spherical bubbles.

25. The cosmetic composition according to claim 17, wherein the internal surface energy a is higher than the external surface energy B.

26. The cosmetic composition according to claim 17, wherein the internal surface energy a is lower than the external surface energy B.

27. The cosmetic composition according to claim 17, wherein the surface energy β of the external surface of the spherical particles is obtained by chemical treatment with chemical treatment agent.

28. The cosmetic composition according to claim 17 wherein the surface energy β of the external surface of the spherical particles is obtained by physical treatment with a physical treatment agent.

29. The cosmetic composition according to claim 27, wherein the chemical treatment agent is a copolymer of polymethylhydrogensiloxane.

30. The cosmetic composition according to claim 27, wherein the chemical treatment agent is a triethoxy- and/or trimethoxy-silane.

31. The cosmetic composition according to claim 28, wherein the physical treatment is made by deposition of a treatment material by evaporation of a volatile solvent.

32. The cosmetic composition according to claim 28, wherein the physical treatment is achieved by depositing molten material and subsequent solidification.

Description

FORMULATION EXAMPLES

[0032] Some examples are shown below related to the preparation of Janus particles according to the invention and their use for making emulsions and other preparations suited for cosmetic applications.

Example 1

Preparation of Janus Particles (Hydrophilic-Silicone) Functionalized with Dimethicone from Hollow Particles of Hydrophilic Glass

[0033] In a powder mixer, 200 grams of hollow glass particles having an average diameter of 100 microns are added and gently mixed at 100 rpm for 5 minutes. After the addition of a surface treatment agent (copolymer of polymethylhydrogensiloxane-polydimethylsiloxane, 4 grams), the mixture is further stirred for 5 minutes. The mixture thus obtained is thermally treated at 150° C. in air for 24 hours. After the thermal treatment, the mixture is allowed to cool. The coated hollow particles have a surface energy lower than 33 dyn/cm. The particles are then milled using an air-jet grinder with a feed rate of 10 g/min at 7 bars (injection and grinding chamber). The final distribution of particle size is between 0.1 and 20 microns, as measured by means of a laser diffraction granulometer.

Example 2

Preparation of Janus Particles (Hydrophilic-Aliphatic) Functionalized with Behenylcarbamoylpropyl Polysilsesquioxane from Hollow Particles of Hydrophilic Glass

[0034] In a heated powder mixer, 200 grams of hollow glass particles having an average diameter of 200 microns are added and gently mixed at 60 rpm for 5 minutes: after adding 4 grams of behenylcarbamoylpropyl triethoxysilane surface treating agent, the mixture is taken to 80° C. during mixing and mixed completely for 1 hour. 1 gram of an aqueous solution of diluted acid is introduced into the mixer as catalyst and mixing is continued for 2 hours at 80° C. The mixture is then left to cool. The coated hollow particles have a surface energy lower than 33 dyn/cm. The particles are then subjected to intensive mixing at 3000 rpm to break the hollow shells in-situ to achieve a final distribution of particle sizes ranging between 0.1 and 20 microns.

Example 3

Preparation of Janus Particles (Hydrophilic-Aliphatic) Functionalized with Triethoxycaprylylsilane from Hollow Particles of Hydrophilic Glass

[0035] In a heated powder mixer, 200 grams of hollow glass particles having an average diameter of 200 microns are added and gently mixed at 60 rpm for 5 minutes: after adding 4 grams of triethoxycaprylylsilane surface treating agent, the mixture is taken to 80° C. during mixing and mixed completely for 1 hour. 1 gram of an aqueous solution of diluted acid is introduced into the mixer as catalyst and mixing is continued for 2 hours at 80° C. The mixture is then left to cool. The coated hollow particles have a surface energy lower than 33 dyn/cm. The particles are then milled using an air-jet grinder at a feed rate of 10 g/min at 7 bars (injection and grinding chamber). The final distribution of particle size is between 0.1 and 10 microns.

Example 4

Preparation of Janus Particles (Hydrophobic and Hydrophilic) Functionalized by Means of Atmospheric Plasma from Hollow Hydrophobic Polymer Particles

[0036] In an atmospheric plasma reactor, 200 grams of hollow spheres of hydrophobic polymer (polyacrylonitrile/crosslinked polymethyl methacrylate), having average particle size of 80 microns, are added and subjected to treatment for 2 hours. The treated powder becomes hydrophilic with a surface energy greater than 72 dyn/cm. The powder is further milled to break the shells using an air-jet mill at low temperature (under the glass transition temperature of the material) whereby generating the Janus particles. The final distribution of particle size is between 0.1 and 10 microns.

Example 5

Preparation of Water-in-Silicone Emulsion Using the Janus Particles of Example 1

[0037]

TABLE-US-00001 COMPONENTS WEIGHT % Phase A Janus particles (Example 1) 5.0 Dimethicone 75.0 Phase B Water 20.0

[0038] The water-in-silicone emulsion is obtained by preparing Phase A in a beaker at room temperature under mechanical agitation and adding Phase B while generating the emulsion with a high-shear rotor-stator apparatus at 10000 rpm for 5 minutes. The final distribution of the water droplets is between 10 and 150 micron, as detected under optical microscopy. The obtained emulsion is stable against coalescence for more than 6 months at room temperature.

Example 6

Preparation of Water-in-Oil Emulsion Using the Janus Particles of Example 2

[0039]

TABLE-US-00002 COMPONENTS WEIGHT % Phase A Janus particles (Example 2) 5.0 Isohexadecane 45.0 Phase B Water 50.0

[0040] The water-in-oil emulsion is obtained by preparing Phase A in a beaker at room temperature under mechanical agitation and adding Phase B while generating the emulsion with a high-shear rotor-stator apparatus at 10000 rpm for 5 minutes. The final distribution of the water droplets is between 10 and 170 micron, as detected under optical microscopy. The obtained emulsion is stable against coalescence for more than 6 months at room temperature.

Example 7

Preparation of Silicone-in-Oil Emulsion Using the Janus Particles of Example 4

[0041]

TABLE-US-00003 COMPONENTS WEIGHT % Phase A Water 65.0 Janus particles (Example 4) 5.0 Phase B Silicone 30.0

[0042] The water-in-oil emulsion is obtained by preparing Phase A in a beaker at room temperature under mechanical agitation and adding Phase B while generating the emulsion with a high-shear rotor-stator apparatus at 10000 rpm for 5 minutes. The final distribution of the water droplets is between 30 and 200 micron, as detected under optical microscopy. The obtained emulsion is stable against coalescence for more than 6 months at room temperature.

Example 8

Preparation of water-in-Silicone Emulsion with In-Situ Generation of Janus Particles (Humid Grinding)

[0043]

TABLE-US-00004 COMPONENTS WEIGHT % Phase A Glass bubbles treated with silicone 5.0 Dimethicone 40.0 Phase B Dimethicone 35.0 Phase C Water 20.0

[0044] The example shows the case in which the Janus particles are generated in-situ during the production of the emulsion. The glass microbubbles treated with silicone of Example 1 are used as such before grinding. Phase A is prepared in a beaker and calendered in form of mixture into a three-cylinder grinder (calender) by means of which the Janus particles in silicone dispersion are generated. Thus, Phase A is added to Phase B at room temperature and then Phase C is added during the generation of the emulsion with high-shear rotor-stator apparatus at 10000 rpm for 5 minutes. The final distribution of the water droplets is between 10 and 150 micron, as detected under optical microscopy. The obtained emulsion is stable against coalescence for more than 6 months at room temperature.

Example 9

Preparation of Foundation in Water-in-Oil Emulsion

[0045]

TABLE-US-00005 COMPONENTS WEIGHT % Phase A Oils and emollients 35.0 Waxes 10.0 Phase B Janus particles (Example 1) 5.0 Hydrophobic pigments 8.5 Phase C Water 40.0 Preservatives 1.0 Phase D Antioxidants 0.5

[0046] The foundation in water-in-oil emulsion is manufactured as follows. Phase A is taken to 80° C. until the wax melts. Then Phase B is added under mechanical agitation. Phase C is heated to 80° C. and added to Phase A+B during the generation of the emulsion with high-shear rotor-stator apparatus at 10000 rpm for 5 minutes. Then Phase D is added to the mixture under agitation. The temperature is then lowered to ambient temperature under mechanical agitation.

Example 10

Preparation of a “Powder-Cream” Cosmetic Product

[0047]

TABLE-US-00006 COMPONENTS WEIGHT % Phase A Janus particles (Example 1) 10.0 Hydrophobic pigments 10.0 Hydrophobic excipients 10.0 Phase B Dimethicone 6.0 Phase C Water 63.7 Preservatives 0.3

[0048] The “power-cream” product is made as follows. Phase A is mixed in a powder mixer at ambient temperature (2500 rpm for 5 min). Phase B is added to Phase A and further mixed homogeneously (two cycles at 2500 rpm for 5 min). Phase C is then added to Phase A+B and the mixture is mixed until the mass acquires the appearance of a flowing dry powder. Such powder possesses the ability to turn into a cream during application (friction) on the skin and return dry following the evaporation of the water.

Example 11

Preparation of an Oil-in-Water Emulsion For Skincare

[0049]

TABLE-US-00007 COMPONENTS WEIGHT % Phase A Water 60.0 Humectants 7.0 Preservatives 1.0 Rheological modifier 1.0 Janus particles (Example 4) 5.0 Phase B Oils and emollients 25.0 Phase C Antioxidants 0.5 Phase D Active principles 0.5

[0050] The oil-in-water emulsion for skincare is made as follows. Phase A is taken to 50° C. until it is homogeneous. Then Phase C is heated to 50° C. Phase B is added to Phase A during the generation of the emulsion with high-shear rotor-stator apparatus at 10000 rpm for 5 minutes. Then the emulsion is left to cool and Phases C and D are then added with mechanical agitation (200 rpm).

Comparative Example

[0051] A comparative example is provided below which demonstrates the failure of the attempt to form water-in-silicone emulsions using particles obtained with different manufacturing methods (no treatment, no grinding or different treatment-grinding order),

[0052] Comparative powders are described as follows: [0053] Comparative Example I (hydrophilic microbubbles)—Powder in hydrophilic hollow glass spheres, used as such (no coating, no grinding) [0054] Comparative Example II (hydrophilic flakes)—Hydrophilic flakes are obtained as in Example 1 without step of coating (no coating, with grinding) [0055] Comparative Example III (hydrophobic microbubbles)—Hollow hydrophobic glass spheres, obtained as in Example 1 without step of air-jet grinding (with coating, no grinding) [0056] Comparative Example IV (hydrophobic flakes)—Hydrophobic flakes are obtained as in Example 1 by inverting the coating/grinding order (with grinding, with coating)

[0057] The emulsions are prepared in accordance with Example 5 with the different powders (Comparative Examples I-IV) used as Phase A. Phase B (aqueous phase) is added with 0.1% of water-soluble dye FD&C Blue1 to color the water droplets.

[0058] The visual and optical microscopy evaluation show that only Janus particles as described in the present invention generate Pickering emulsions with improved stability. No emulsion is formed when the particles are completely hydrophilic (hollow spheres or flakes) or when hollow hydrophobic spheres are used (Comparative Example I, Comparative Example II and Comparative Example III, respectively). Hydrophobic flakes (Comparative Example IV) lead to a Pickering emulsion based on an intermediate mean wetting between the aqueous phase and the silicone phase: however, such emulsions show a coarser droplet size and a lower stability against coalescence, as demonstrated by an accelerated stability test (in centrifuge at 4000 rpm for 2 minutes or 2500 rpm for 10 min) compared to the Pickering emulsion based on Janus particles which is the object of the present invention.