Compositions Comprising Solid Particles Encapsulated In A Cross-Linked Silicone Matrix, And Methods Of Making The Same

• US 20120269893A1
• Filed: 07/03/2012
• Published: 10/25/2012
• Est. Priority Date: 09/03/2008
• Status: Active Grant

• Current Assignee: Wilson Lee
• Original Assignee: Wilson Lee
• Inventors: Lee, Wilson
• Granted Patent: US 8,932,564 B2
• Time in Patent Office: Days
• US Class Current: 424/486
• CPC Class Codes: A61K 2800/412 Microsized, i.e. having sizes between 0.1 and 100 microns
• CPC Class Codes: A61K 2800/522 Antioxidants; Radical scavengers
• CPC Class Codes: A61K 2800/624 by macromolecular compounds
• CPC Class Codes: A61K 2800/63 More than one coating
• CPC Class Codes: A61K 2800/651 The particulate/core comprising inorganic material
• CPC Class Codes: A61K 8/0241 Containing particulates characterized by their shape and/or structure see also A61K8/04, A61K8/11, and A61K8/14, further aspects are classified in A61K2800/40 and subcodes
• CPC Class Codes: A61K 8/11 Encapsulated compositions
• CPC Class Codes: A61K 8/29 Titanium; Compounds thereof
• CPC Class Codes: A61K 8/58 containing atoms other than carbon, hydrogen, halogen, oxygen, nitrogen, sulfur or phosphorus
• CPC Class Codes: A61K 8/8164 Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical, and containing at least one other carboxyl radical in the molecule, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers, e.g. poly (methyl vinyl ether-co-maleic anhydride)
• CPC Class Codes: A61K 8/893 modified by an alkoxy or aryloxy group, e.g. behenoxy dimethicone or stearoxy dimethicone
• CPC Class Codes: A61P 17/18 Antioxidants, e.g. antiradicals preparations for protection against sunlight A61Q17/00
• CPC Class Codes: A61Q 17/04 Topical preparations for affording protection against sunlight or other radiation; Topical sun tanning preparations
• CPC Class Codes: B01J 13/14 Polymerisation; cross-linking
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C09C 1/3692 Combinations of treatments provided for in groups C09C1/3615 - C09C1/3684
• CPC Class Codes: Y10T 428/2989 Microcapsule with solid core [includes liposome]

Abstract

The present invention relates to topical compositions containing solid particles that are stabilized via encapsulation into a cross-linked silicone matrix. The solid particles are preferably formed of a metal oxide, such as zinc oxide or titanium dioxide, and the cross-linked silicone matrix is preferably formed by cross-linking a silicone having branched reactive alkoxyl moieties in the presence of a stannous carboxylate cross-linking agent. The stabilized particles of the present invention can readily be used either alone or in combination with other skin care actives to form topical compositions with improved stability and performance.

Claims

1. A topical composition comprising a dispersion of treated particles in a cosmetically or pharmaceutically acceptable carrier, wherein each of said treated particles comprises one or more core particles encapsulated in a cross-linked silicone matrix.

2. The composition of claim 1, wherein the treated particles have an average particle size ranging from about 1 micron to about 50 microns, and the core particles have an average particle size ranging from about 0.001 micron to about 0.5 micron.

3. The composition of claim 1, wherein the cross-linked silicone matrix is formed by cross- linking a silicone having branched reactive alkoxyl moieties.

4. The composition of claim 3, wherein the branched reactive moieties comprise ethoxy or ethoxysilylethyl groups.

5. The composition of claim 3, wherein the cross-linked silicone matrix is formed by cross- linking triethoxysilylethyl polydimethylsiloxyethyl hexyl dimethicone.

6. The composition of claim 1, wherein the core particles comprise one or more metal oxides.

7. The composition of claim 6, wherein the core particles comprises titanium dioxide, zinc oxide, or a combination thereof.

8. The composition of claim 6, further comprising at least one organic compound susceptible to oxidative decomposition or degradation.

9. The composition of claim 8, wherein said organic compound is an organic sunscreen agent susceptible to oxidative decomposition or degradation.

10. The composition of claim 9, wherein the organic sunscreen agent is 4,4′

-t-butyl methoxydibenzoylmethane.

11. The composition of claim 8, wherein said organic compound is an organic dye susceptible to oxidative decomposition or degradation.

12. The composition of claim 1, wherein each of the core particles is first coated by an inner layer of an anionic polymer selected from the group consisting of glycols, glycerin, water-soluble gums, carbomer gels, hydrogels, acrylates copolymers, methyl vinyl ether and maleic anhydride copolymers (PVM/MA copolymers), and quaternary amine compounds and then encapsulated into the cross-linked silicone matrix.

13. The composition of claim 12, wherein the core particles have a density that is larger than the densities of the anionic polymer and the silicone, and wherein the anionic polymer has a density that is lager than that of the silicone.

14. A treated particle comprising one or more titanium dioxide or zinc oxide core particles encapsulated in a cross-linked silicone matrix, wherein said treated particle has a particle size ranging from about 1 micron to about 50 microns.

15. A method for forming treated particles, comprising:

(a) coating core particles having an average particle size ranging from about 0.001 micron to about 0.5 micron with silicone;

(b) contacting the coated particles with a cross-linking agent, wherein the cross- linking agent comprises a stannous carboxylate capable of effectuating cross-linking of the silicone coating, thereby forming a cross-linked structure with the core particles encapsulated therein; and

(c) reducing the cross-linked structure into treated particles having an average particle size ranging from about 1 micron to about 50 microns, wherein each of the treated particles comprises one or more of said core particles encapsulated in a cross-linked silicone matrix.

16. The method of claim 15, wherein the silicone is triethoxysilylethyl polydimethylsiloxyethyl hexyl dimethicone, wherein the stannous carboxylate is stannous octoate, and wherein cross-linking of the silicone coating is effectuated at room temperature with continuous mixing.