The present invention relates to particle stabilizing compositions suitable for use in fabric care products, home care products, diapers, incontinence articles, feminine care products, pharmaceuticals, oral care products, antiperspirants, deodorants, personal cleansing products, skin care products and hair care products comprising: a) an emulsion comprising from about 1% to about 99% by weight of the emulsion of an internal phase and from about 1% to about 99% by weight of the emulsion of an external phase; b) a charged species that is present in the emulsion; and c) charged insoluble solid particles which are dispersed in the emulsion wherein the charged species possesses a charge which is opposed to that of the charged insoluble solid particles and wherein essentially all of the charged species and charged insoluble solid particles accumulate at the interface of the emulsion and wherein Brownian motion is not exhibited by the charged insoluble solid particles.

Description of the Invention

SUMMARY OF THE INVENTION

The present invention relates to a particle stabilizing composition comprising: a) an emulsion, comprising from about 1% to about 99%, by weight of the emulsion, of an internal phase and from about 1% to about 99%, by weight of the emulsion, of an external phase; b) a charged species that is present in the emulsion; and c) charged insoluble solid particles which are dispersed in said emulsion; wherein the charged species possesses a charge which is opposed to that of the charged insoluble solid particles and wherein essentially all of the charged species and charged insoluble solid particles accumulate at the interface of the emulsion and wherein Brownian motion is not exhibited by the charged insoluble solid particles.

In addition to the charged species and particles within the present invention, the composition may also comprise additional charged or even uncharged particulate material dispersed in the emulsion.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to compositions, particularly cosmetic compositions which provide a natural appearance to the substrate to which it is applied (e.g., hair, skin, and/or nails), and especially foundation compositions. In particular, the cosmetic compositions of the present invention are formulated such that agglomeration of an insoluble solid particle in the product and on the skin is minimized. In cosmetic compositions, the insoluble solid particle of the present invention may be a pigment. Using the present invention in foundations, the pigment has a significantly reduced tendency to collect in the fine lines or wrinkles (or otherwise agglomerate on the skin), a cakey appearance is avoided and the skin has a natural appearance. Without being bound or limited by theory, it is believed that as a result of minimizing agglomeration of the pigment, the pigment is uniformly distributed throughout the product and that, upon application to the skin, the pigment in the composition is uniformly deposited on the skin as perceived by the eye. In any event, the distribution of the pigment and/or its appearance on the skin becomes substantially independent of skin topography.

As used herein, the term "cosmetic compositions" refers to compositions for application to the hair, nails and/or skin, especially the face, which contain at least about 0.01% and up to about 50% of pigment as hereinafter defined. Cosmetic compositions include, but are not limited to, foundations, blush, mascara, eyeshadow, eyeliner, lipstick, nail polish and tinted moisturizers. The invention described herein is particularly suited for foundation compositions. As used herein, the term "foundation" refers to a liquid, solid or semi-solid facial skin cosmetic composition which includes, but is not limited to, lotions, creams, gels, serums, compacts, sticks and pastes all of which may or may not be applied using an applicator, substrate, sponge, a combination thereof or a similar means or some type of mechanical delivery such as air brush, electrostatic spray, a combination thereof or a similar means.

The benefits of the present invention are most apparent for liquid foundations and solid compact emulsion foundations. As used herein, "liquid foundations" refers to liquid or cream type foundation products which may range from thin liquids which are pourable (i.e., from a bottle) to viscous gels or creams which are often packaged in jars, tubes or pump-type dispensers. Liquid foundations typically have viscosities in the ranges of from about 10 to about 10,000 centipoise measured at a shear rate of 100 1/s. Viscosity can be measured using a typical rotational viscometer such as a Haake RS100 with 35/1 degree cone and plate geometry or the equivalent thereof. The viscosity is determined on the composition after the composition has been allowed to stabilize following its preparation, generally at least 24 hours under the conditions of 25.degree. C..+-.1.degree. C. and an ambient pressure and is measured with the composition at a temperature of 25.degree. C..+-.1.degree. C., after 30 seconds rotation. Liquid foundations are typically applied to the skin by finger.

As used herein, "solid compact emulsion foundations" means foundations compositions which are made from an emulsion which is gelled to a solid or semi-solid state, for example, by a solid wax-like network, liquid crystals, polymers, surfactant/polymer/protein mixtures, etc. Due to their solid or semi-solid consistency, solid emulsions are typically characterized by their hardness, which can be measured by their resistance to penetration by a probe or needle which is dropped or pushed into the solidfied composition. Hardness can be measured using typically penetrometers such as a Voland-Stevens LFRA Texture Analyzer available from Texture Technologies Corp. with Stevens probe #TA-PG (5 mm diameter Cylinder) or equivalent thereof. Solid emulsion foundations typically have a hardness in the range of 30-500 grams force as measured as the minimum force required to push a cylinder of 5 mm diameter to a depth of 3 mm into the composition at a speed of 0.2 mm/second. Hardness is determined after the composition has been allowed to stabilize following its preparation, generally at least 24 hours under the conditions of 25.degree. C..+-.1.degree. C. and ambient pressure and is measured with the composition at a temperature of 25.degree. C..+-.1.degree. C. Solid emulsion foundations include for example compacts and sticks, and are typically packaged in a compact or plastic cylinder and are typically applied to the skin by finger or sponge applicator. Typically, the foundations are used over a large area of skin, such as the face and neck.

As used herein, an "emulsion composition" means a composition comprising at least two distinct phases known as the internal phase and the external phase.

As used herein, the term "internal phase" of the emulsion composition is the phase wherein the material or materials of said phase are dispersed as small particles within another distinct phase of the emulsion composition.

As used herein, the term "external phase" of the emulsion composition is the phase wherein the internal phase is dispersed within.

Preferred compositions of the present invention are formulated such that the aqueous phase of the composition (whether as the internal phase or as the external phase) has a pH ranging from about 5 to about 10, more preferably from about 6 to about 8, most preferably from about 6.5 to about 7.5, although the benefits of the invention (natural appearance cosmetics) can be achieved at pHs as low as 2. The cosmetic compositions herein can be applied by any conventional means including, for example, with the fingers, with an applicator such as a brush or a sponge, or via aerolization, including, for example, airbrush or electrostatic spray devices.

The compositions of the present invention, including the materials contained therein and processes for making them, are described in detail as follows.

I. Materials

The compositions of the present invention are comprise the following materials:

A. The Emulsion

The compositions of the present invention comprise an emulsion, wherein the internal phase can be a liquid, gas, solid, liquid crystal, gel, or combinations thereof. In preferred embodiments, the emulsion is selected from the group consisting of water-in-oil emulsions, oil-in-water emulsions, water-in-silicone, silicone-in-water, water-in-silicone elastomer emulsions, silicone elastomer-in-water emulsions and combinations thereof. Preferably an oil-in-water or water-in-oil emulsion is used. More preferably, compositions of the present invention comprise water-in-oil emulsions. When the compositions of the present invention are used as cosmetic products, the compositions typically comprise from about 50% to about 99.9%, preferably from about 70% to about 95%, more preferably from about 80% to about 90%, of an emulsion. Solid emulsion compact foundation compositions of the present invention typically comprise from about 50% to about 99.9%, preferably from about 60% to about 99.9%, more preferably from about 70% to about 99.9%, by weight of the composition, of an emulsion. Liquid foundation compositions typically comprise from about 80% to about 99.9%, by weight of the composition, of an emulsion.

The emulsion may also contain an anti-foaming agent to minimize foaming upon application to a substrate. Anti-foaming agents include high molecular weight silicones and other materials well known in the art for such use.

Suitable emulsions may have a wide range of viscosities, depending on the desired product form. Exemplary low viscosity emulsions, which are preferred, have a viscosity of about 50 centistokes or less, more preferably about 10 centistokes or less, and most perferably from about 5 centistokes or less.

The emulsion comprises an internal (i.e., dispersed) phase and an external phase. When water is the internal phase (i.e., the aqueous phase of water-in-oil or water-in-silicone emulsion), the emulsion typically comprises from about 1% to about 99%, preferably from about 15% to about 90%, more preferably from about 40% to about 85%, by weight of the emulsion. When water is the external phase, the emulsion typically comprises from about 1% to about 99%, preferably from about 10% to about 85%, more preferably from about 15% to about 60%, by weight of the emulsion. Highly concentrated emulsions wherein the internal phase comprises a high proportion of the emulsion and wherein the proportion of the external phase is minimized, are very stable and are, therefore, preferred herein.

The internal phase is typically in the form of droplets which typically range in size from about 0.15 to about 40 microns in diameter, preferably from about 0.20 to about 30 microns and most preferably from about 0.25 to about 20 microns. The particle size of the droplets comprising the internal phase of the emulsion can be determined as described in the "Analytical Methods" section hereinafter.

It is understood that the oil phase of the emulsions herein (whether as the external phase or as the internal phase) can comprise a wide variety of hydrophobic and other components. Numerous examples can be found in Sagarin, Cosmetics, Science and Technology, 2nd edition, Vol. 1, pp. 32-43 (1972), and Cosmetic Bench Reference, Cosmetics & Toiletries, pp. 1.19-1.22 (1996) herein incorporated by reference. Nonlimiting examples of suitable hydrophobic components for use in the compositions herein include those selected from the group consisting of:

(i) Mineral oil, which is also known as petrolatum liquid, is a mixture of liquid hydrocarbons obtained from petroleum. See, The Merck Index, Tenth Edition, Entry 7048, p. 1033 (1983) and International Cosmetic Ingredient Dictionary, Fifth Edition, vol. 1, p. 415-417 (1993), which are incorporated by reference herein in their entirety.

(ii) Petrolatum, which is also known as petroleum jelly, is a colloidal system of nonstraight-chain solid hydrocarbons and high-boiling liquid hydrocarbons, in which most of the liquid hydrocarbons are held inside the micelles or micelle-like self assembled aggregates. See, The Merck Index, Tenth Edition, Entry 7047, p. 1033 (1983); Schindler, Drug. Cosmet. Ind., 89, 36-37, 76, 78-80, 82 (1961); and International Cosmetic Ingredient Dictionary, Fifth Edition, vol. 1, p. 537 (1993), which are incorporated by reference herein in their entirety.

(iii) Straight and branched chain hydrocarbons having from about 7 to about 40 carbon atoms. Nonlimiting examples of these hydrocarbon materials include dodecane, isododecane, squalane, cholesterol, hydrogenated polyisobutylene, dodecosane (i.e. a C.sub.22 hydrocarbon), hexadecane, isohexadecane (a commercially available hydrocarbon sold as Permethyl.RTM. 101A by Presperse, South Plainfield, N.J.). Also useful are the C7-C40 isoparaffins, which are C7-C40 branched hydrocarbons.

(iv) C1-C30 alcohol esters of C1-C30 carboxylic acids and of C2-C30 dicarboxylic acids, including straight and branched chain materials as well as aromatic derivatives (as used herein in reference to the hydrophobic component, mono- and poly-carboxylic acids include straight chain, branched chain and aryl carboxylic acids). Nonlimiting examples include isononyl isononanoate, methyl isostearate, ethyl isostearate, diisopropyl sebacate, diisopropyl adipate, isopropyl myristate, isopropyl palmitate, methyl palmitate, myristyl propionate, 2-ethylhexyl palmitate, isodecyl neopentanoate, di-2-ethylhexyl maleate, cetyl palmitate, myristyl myristate, stearyl stearate, isopropyl stearate, methyl stearate, cetyl stearate, behenyl behenate, dioctyl maleate, dioctyl sebacate, diisopropyl adipate, cetyl octanoate, diisopropyl dilinoleate.

(v) Mono-, di- and tri-glycerides of C1-C30 carboxylic acids, e.g., caprylic/capric triglyceride, PEG-6 caprylic/capric triglyceride, PEG-8 caprylic/capric triglyceride.

(vi) Alkylene glycol esters of C1-C30 carboxylic acids, e.g., ethylene glycol mono- and di-esters, and propylene glycol mono- and di-esters of C1-C30 carboxylic acids e.g., ethylene glycol distearate.

(vii) Propoxylated and ethoxylated derivatives of the foregoing materials.

(viii) C1-C30 mono- and poly-esters of sugars and related materials. These esters are derived from a sugar or polyol moiety and one or more carboxylic acid moieties. Depending on the constituent acid and sugar, these esters can be in either liquid or solid form at room temperature. Examples of liquid esters include: glucose tetraoleate, the glucose tetraesters of soybean oil fatty acids (unsaturated), the mannose tetraesters of mixed soybean oil fatty acids, the galactose tetraesters of oleic acid, the arabinose tetraesters of linoleic acid, xylose tetralinoleate, galactose pentaoleate, sorbitol tetraoleate, the sorbitol hexaesters of unsaturated soybean oil fatty acids, xylitol pentaoleate, sucrose tetraoleate, sucrose pentaoletate, sucrose hexaoleate, sucrose hepatoleate, sucrose octaoleate, and mixtures thereof. Examples of solid esters include: sorbitol hexaester in which the carboxylic acid ester moieties are palmitoleate and arachidate in a 1:2 molar ratio; the octaester of raffinose in which the carboxylic acid ester moieties are linoleate and behenate in a 1:3 molar ratio; the heptaester of maltose wherein the esterifying carboxylic acid moieties are sunflower seed oil fatty acids and lignocerate in a 3:4 molar ratio; the octaester of sucrose wherein the esterifying carboxylic acid moieties are oleate and behenate in a 2:6 molar ratio; and the octaester of sucrose wherein the esterifying carboxylic acid moieties are laurate, linoleate and behenate in a 1:3:4 molar ratio. A preferred solid material is sucrose polyester in which the degree of esterification is 7-8, and in which the fatty acid moieties are C18 mono- and/or di-unsaturated and behenic, in a molar ratio of unsaturates:behenic of 1:7 to 3:5. A particularly preferred solid sugar polyester is the octaester of sucrose in which there are about 7 behenic fatty acid moieties and about 1 oleic acid moiety in the molecule. Other materials include cottonseed oil or soybean oil fatty acid esters of sucrose. The ester materials are further described in, U.S. Pat. Nos. 2,831,854, 4,005,196, to Jandacek, issued Jan. 25, 1977; U.S. Pat. No. 4,005,195, to Jandacek, issued Jan. 25, 1977, U.S. Pat. No. 5,306,516, to Letton et al., issued Apr. 26, 1994; U.S. Pat. No. 5,306,515, to Letton et al., issued Apr. 26, 1994; U.S. Pat. No. 5,305,514, to Letton et al., issued Apr. 26, 1994; U.S. Pat. No. 4,797,300, to Jandacek et al., issued Jan. 10, 1989; U.S. Pat. No. 3,963,699, to Rizzi et al, issued Jun. 15, 1976; U.S. Pat. No. 4,518,772, to Volpenhein, issued May 21, 1985; and U.S. Pat. No. 4,517,360, to Volpenhein, issued May 21, 1985; all of which are incorporated by reference herein in their entirety.

(ix) Organopolysiloxane oils. The organopolysiloxane oil may be volatile, non-volatile, or a mixture of volatile and non-volatile silicones. The term "nonvolatile" as used in this context refers to those silicones that are liquid under ambient conditions and have a flash point (under one atmospheric of pressure) of or greater than about 100.degree. C. The term "volatile" as used in this context refers to all other silicone oils. Suitable organopolysiloxanes can be selected from a wide variety of silicones spanning a broad range of volatilities and viscosities. Nonlimiting examples of suitable silicones are disclosed in U.S. Pat. No. 5,069,897, to Orr, issued Dec. 3, 1991, and Cosmetic Bench Reference, Cosmetics & Toiletries, pp. 1.33-1.34 (1996) which are incorporated by reference herein in its entirety. Examples of suitable organopolysiloxane oils include polyalkylsiloxanes, cyclic polyalkylsiloxanes, and polyalkylarylsiloxanes.

Polyalkylsiloxanes useful in the composition herein include polyalkylsiloxanes with viscosities of from about 0.5 to about 1,000,000 centistokes at 25.degree. C. Such polyalkylsiloxanes can be represented by the general chemical formula R.sub.3SiO[R.sub.2SiO].sub.xSiR.sub.3 wherein R is an alkyl group having from one to about 30 carbon atoms (preferably R is methyl or ethyl, more preferably methyl; also mixed alkyl groups can be used in the same molecule), and x is an integer from 0 to about 10,000, chosen to achieve the desired molecular weight which can range to over about 10,000,000. Commercially available polyalkylsiloxanes include the polydimethylsiloxanes, which are also known as dimethicones, examples of which include the Vicasil.RTM. series sold by General Electric Company and the Dow Corning.RTM. 200 series sold by Dow Corning Corporation. Specific examples of suitable polydimethylsiloxanes include Dow Corning.RTM. 200 fluid having a viscosity of 0.65 centistokes and a boiling point of 100.degree. C., Dow Corning.RTM. 225 fluid having a viscosity of 10 centistokes and a boiling point greater than 200.degree. C., and Dow Corning.RTM. 200 fluids having viscosities of 50, 350, and 12,500 centistokes, respectively, and boiling points greater than 200.degree. C. Examples of suitable alkyl and substituted dimethicones include those represented by the chemical formula (CH.sub.3).sub.3SiO[(CH.sub.3).sub.2SiO].sub.x[CH.sub.3RSiO].sub.- ySi(CH.sub.3).sub.3 wherein R is straight or branched chain alkyl having from two to about 30 carbon atoms and x and y are each integers of 1 or greater selected to achieve the desired molecular weight which can range to over about 10,000,000. Examples of these alkyl-substituted dimethicones include cetyl dimethicone and lauryl dimethicone.

Cyclic polyalkylsiloxanes suitable for use in the composition include those represented by the chemical formula [SiR.sub.2--O].sub.n wherein R is an alkyl group (preferably R is methyl or ethyl, more preferably methyl) and n is an integer from about 3 to about 8, more preferably n is an integer from about 3 to about 7, and most preferably n is an integer from about 4 to about 6. When R is methyl, these materials are typically referred to as cyclomethicones. Commercially available cyclomethicones include Dow Corning.RTM. 244 fluid having a viscosity of 2.5 centistokes, and a boiling point of 172.degree. C., which primarily contains the cyclomethicone tetramer (i.e. n=4), Dow Corning.RTM. 344 fluid having a viscosity of 2.5 centistokes and a boiling point of 178.degree. C., which primarily contains a mixture of the cyclomethicone tetramer and pentamer (i.e. n=4 and 5), Dow Corning.RTM. 245 fluid having a viscosity of 4.2 centistokes and a boiling point of 205.degree. C., which primarily contains the cyclomethicone pentamer (i.e. n=5), and Dow Corning.RTM. 345 fluid having a viscosity of 4.5 centistokes and a boiling point of 217.degree., which primarily contains a mixture of the cyclomethicone tetramer, pentamer, and hexamer (i.e. n=4, 5, and 6).

Also useful are materials such as trimethylsiloxysilicate, which is a polymeric material corresponding to the general chemical formula [(CH.sub.2).sub.3SiO.sub.1/2].sub.x[SiO.sub.2].sub.y, wherein x is an integer from about 1 to about 500 and y is an integer from about 1 to about 500. A commercially available trimethylsiloxysilicate is sold as a mixture with dimethicone as Dow Corning.RTM. 593 fluid.

Dimethiconols are also suitable for use in the composition. These compounds can be represented by the chemical formulas R.sub.3SiO[R.sub.2SiO].sub.xSiR.sub.2OH and HOR.sub.2SiO[R.sub.2SiO].sub.xSiR.sub.2OH wherein R is an alkyl group (preferably R is methyl or ethyl, more preferably methyl) and x is an integer from 0 to about 500, chosen to achieve the desired molecular weight. Commercially available dimethiconols are typically sold as mixtures with dimethicone or cyclomethicone (e.g. Dow Corning.RTM. 1401, 1402, and 1403 fluids).

Polyalkylaryl siloxanes are also suitable for use in the composition. Polymethylphenyl siloxanes having viscosities from about 15 to about 65 centistokes at 25.degree. C. are especially useful.

Preferred for use herein are organopolysiloxanes selected from the group consisting of polyalkylsiloxanes, alkyl substituted dimethicones, cyclomethicones, trimethylsiloxysilicates, dimethiconols, polyalkylaryl siloxanes, and mixtures thereof. More preferred for use herein are polyalkylsiloxanes and cyclomethicones. Preferred among the polyalkylsiloxanes are dimethicones.

(x) Vegetable oils and hydrogenated vegetable oils. Examples of vegetable oils and hydrogenated vegetable oils include safflower oil, castor oil, coconut oil, cottonseed oil, menhaden oil, palm kernel oil, palm oil, peanut oil, soybean oil, rapeseed oil, linseed oil, rice bran oil, pine oil, sesame oil, sunflower seed oil, hydrogenated safflower oil, hydrogenated castor oil, hydrogenated coconut oil, hydrogenated cottonseed oil, hydrogenated menhaden oil, hydrogenated palm kernel oil, hydrogenated palm oil, hydrogenated peanut oil, hydrogenated soybean oil, hydrogenated rapeseed oil, hydrogenated linseed oil, hydrogenated rice bran oil, hydrogenated sesame oil, hydrogenated sunflower seed oil, and mixtures thereof.

(xi) Animal fats and oils, e.g., lanolin and derivatives thereof, cod liver oil.

(xii) Other materials: Also useful are C4-C20 alkyl ethers of polypropylene glycols, C1-C20 carboxylic acid esters of polypropylene glycols, and di-C8-C30 alkyl ethers. Nonlimiting examples of these materials include PPG-14 butyl ether, PPG-15 stearyl ether, dioctyl ether, dodecyl octyl ether, and mixtures thereof.

Preferably, the oil phase comprises silicones. More preferably from about 30% to about 95%, most preferably from about 50% to about 90% of the oil phase is volatile silicones, non-volatile silicones and mixtures thereof. Still more preferably, these silicones are chosen from cyclomethicones, trimethicones, such as methyl trimethicone, dimethicones and mixtures thereof. Thus one of the most preferred oil phases can be considered, and is thus defined as a "silicone" phase. For purposes of the present invention, the terms "water-in-oil emulsions" and "oil-in-water emulsions" encompass water-in-silicone emulsions and silicone-in-water emulsions, respectively.

B. The Charged Species

The compositions herein also comprise a charged species that possesses a charge that is opposite that of the charged insoluble solid particles (hereinafter described). This species can be present within the internal phase of the emulsion, at the interface of the emulsion, and/or in the external phase of the emulsion (in bulk). Typically and preferably, a substantial portion of the species are present at the interface of the internal phase and the external phase of the emulsion.

The species can be for example, hydrogen ion, an acid, a base, an ionic polymer, an ionic surfactant, a lipid or mixtures thereof. Ionic surfactants include cationic, anionic and amphoteric surfactants. Suitable ionic surfactants for use herein are described hereinafter in the subsection entitled "Emulsifiers".

In a highly preferred embodiment of the present invention, the species comprises an ionic polymer and is present at the interface between the internal phase and the external phase of the emulsion. In this embodiment of the invention, the emulsion droplet contains an amount of ionic polymer sufficient to cover the surface of the droplet. In particular, the present invention comprises from about 0.1% to about 25%, more preferably from about 0.5% to about 10%, and most preferably from about 0.5% to about 5%, by weight of the composition, of charged species.

Suitable anionic polymers for use in this embodiment of the invention include, but are not limited to, copolymers of polyacrylate, ammonium polyacrylate, sodium polyacrylate, potassium polyacrylate, ethylene acrylic acid copolymer, hydrolyzed wheat protein polysiloxane copolymer, dimethicone copolyol phosphate, phosphate ester, sodium chondroiton sulfate, sodium hyaluronate, ammonium hyaluronate, sodium alginate, ammonium alginate, diglycol cyclohexanedimethanol isophthalates sulfoisophthalates copolymer and mixtures therof.

Suitable cationic polymers for use in this embodiment of the invention include, but are not limited to, cellulose derivatives, polysaccharides, chitosan, derivatives of chitosan, chitosan di-pyrrolidone carboxylate, hydroxypropyl chitosan, quaterniums, quaternium-80, quaternium-61, polyquaterniums, hydroxyethyl cetyldimonium phosphate, adipic acid/dimethylaminohydroxypropyl diethyltriamine copolymer, guar hydroxypropyltrimonium chloride, dimethicone copolyol amine(s), amidomethicones, dimethicone salts and mixtures thereof.

Exemplary lipids include charged lipids which are compatible with skin such as phospholipids, simple carboxylic esters including fats (esters of fatty acids with glycerol), and waxes (sterol esters, esters of fatty acids with alcohols other than glycerol), complex carboxylic esters (glycerophospholipids, glycoglycerolipids, glycoglycerolipid sulfates), complex lipids (lipids containing amides, sphinogolipids, gylcosphingolipids), precursors and derived lipids including phosphatidic acid, bile acids, and bases such as sphinganines, hydrocarbons containing charged moieties (either straight or simple branched chain), lipid vitamins and hormones with multiple functional charged groups, and lipoproteins.

C. Charged Insoluble Solid Particles

The composition of the present invention includes charged insoluble solid particles. These charged particles of the present invention preferably have a particle size of less than 200 .mu.m. Typically, the particles will have a particle size from about 0.001 .mu.m to about 50 .mu.m, still more preferably from about 0.005 .mu.m to about 1 .mu.m, and even more preferably from about 0.01 .mu.m to about 0.1 .mu.m in diameter.

Typical particle levels are selected depending upon the particular purpose of the composition. For example, where it is desired to deliver color benefits, pigment particles conferring the desired hues can be incorporated. Where the desire is to treat or prevent symptoms such as diaper rash, inflammation, and/or other skin disorders, the present invention allows for insoluble skin care agents to be delivered more uniformly to the skin. Determination of the levels and particle types is within the skill of the artisan. Particles that are generally recognized as safe, and are listed in C.T.F.A. Cosmetic Ingredient Handbook, Sixth Ed., Cosmetic and Fragrance Assn., Inc., Washington D.C. (1995), incorporated herein by reference, can be used.

In the compositions of the present invention, it is preferable to incorporate from about 0.01% to about 80%, more preferably from about 0.1% to about 50%, still more preferably from about 1% to about 30%, and most preferably from about 5% to about 20%, by weight of the composition, of charged insoluble solid particles.

The particles can be scattering or non-scattering and may or may not impart color. Suitable particles include bismuth oxychloride, titanated mica, fumed silica, spherical silica, polymethylmethacrylate, micronized teflon, boron nitride, acrylate polymers, aluminum silicate, aluminum starch octenylsuccinate, bentonite, calcium silicate, cellulose, chalk, corn starch, diatomaceous earth, fuller's earth, glyceryl starch, hectorite, hydrated silica, kaolin, magnesium aluminum silicate, magnesium carbonate, magnesium hydroxide, magnesium oxide, magnesium silicate, magnesium trisilicate, maltodextrin, montmorillonite, microcrystaline cellulose, rice starch, silica, talc, mica, titanium dioxide, zinc laurate, zinc myristate, zinc neodecanoate, zinc rosinate, zinc stearate, polyethylene, alumina, attapulgite, calcium carbonate, calcium silicate, dextran, kaolin, nylon, silica silylate, silk powder, sericite, soy flour, tin oxide, titanium hydroxide, trimagnesium phosphate, walnut shell powder, or mixtures thereof. The above mentioned particles may be surface treated with lecithin, amino acids, mineral oil, silicone oil, or various other agents either alone or in combination, which coat the powder surface and render the particles hydrophobic in nature.

Water insoluble solid particles of various shapes and densities are useful. In a preferred embodiment, the particles tend to have a spherical, an oval, an irregular, or any other shape in which the ratio of the largest dimension to the smallest dimension (defined as the aspect ratio) is less than 10. More preferably, the aspect ratio of the particles is less than 8. Still more preferably, the aspect ratio of the particles is less than 5.

Particles useful in the present invention can be nano, micro, and mixtures thereof, and can be natural, synthetic, or semi-synthetic in composition. Hybrid particles are also useful. Synthetic particles can be made of either cross-linked or non cross-linked polymers. The particles of the present invention can have surface charges or their surface can be modified with organic or inorganic materials such as surfactants, polymers, and inorganic materials. Particle complexes are also useful.

Non limiting examples of natural particles include various precipitated silica particles in hydrophilic and hydrophobic forms available from Degussa-Huls under the trade name Sipernet. Snowtex colloidal silica particles available from Nissan Chemical America Corporation.

Examples of synthetic particles include nylon, silicone resins, poly(meth)acrylates, polyethylene, polyester, polypropylene, polystyrene, polyurethane, polyamide, epoxy resins, urea resins, and acrylic powders. Non limiting examples of useful particles are Microease 110S, 114S, 116 (micronized synthetic waxes), Micropoly 210, 250S (micronized polyethylene), Microslip (micronized polytetrafluoroethylene), and Microsilk (combination of polyethylene and polytetrafluoroethylene), all of which are available from Micro Powder, Inc. Other examples include Luna (smooth silica particles) particles available from Phenomenex, MP-2200 (polymethylmethacrylate), EA-209 (ethylene/acrylate copolymer), SP-501(nylon-12), ES-830 (polymethly methacrylate), BPD-800, BPD-500 (polyurethane) particles available from Kobo Products, Inc. and silicone resins sold under the name Tospearl particles by GE Silicones. Ganzpearl GS-0605 crosslinked polystyrene (available from Presperse) is also useful.

Non limiting examples of hybrid particles include Ganzpearl GSC-30SR (Sericite & crosslinked polystyrene hybrid powder), and SM-1000, SM-200 (mica and silica hybrid powder available from Presperse).

In one embodiment of the present invention, the particles used in the composition are hollow particles. In a preferred embodiment, the hollow particles are fluid-encapsulated, flexible microspheres. The microspheres are structurally hollow, however, they may contain various fluids, which encompass liquids and gases and their isomers. The gases include, but not limited to, butane, pentane, air, nitrogen, oxygen, carbon dioxide, and dimethyl ether. If used, liquids may only partially fill the microspheres. The liquids include water and any compatible solvent. The liquids may also contain vitamins, amino acids, proteins and protein derivatives, herbal extracts, pigments, dyes, antimicrobial agents, chelating agents, UV absorbers, optical brighteners, silicone compounds, perfumes, humectants which are generally water soluble, additional conditioning agents which are generally water insoluble, and mixtures thereof. In one embodiment, water soluble components are preferred encompassed material. In another embodiment, components selected from the group consisting of vitamins, amino acids, proteins, protein derivatives, herbal extracts, and mixtures thereof are preferred encompassed material. In yet another embodiment, components selected from the group consisting of vitamin E, pantothenyl ethyl ether, panthenol, Polygonum multiflori extracts, and mixtures thereof are preferred encompassed material.

The particles of the present invention can have surface charges or their surface can be modified with organic or inorganic materials such as surfactants, polymers, and inorganic materials. Particle complexes are also useful. Non-limiting examples of complexes of gas-encapsulated microspheres are DSPCS-I2.TM. (silica modified ethylene/methacrylate copolymer microsphere) and SPCAT-I2.TM. (talc modified ethylene/methacrylate copolymer microsphere). Both of these are available from Kobo Products, Inc.

The surface of the particle may be charged through a static development or with the attachment of various ionic groups directly or linked via short, long or branched alkyl groups. The surface charge can be anionic, cationic, zwitterionic or amphoteric in nature.

The wall of the particles of the present invention may be formed from a thermoplastic material. The thermoplastic material may be a polymer or copolymer of at least one monomer selected from the following groups: acrylates, methacrylates, styrene, substituted styrene, unsaturated dihalides, acrylonitriles, methacrylonitrile. The thermoplastic materials may contain amide, ester, urethane, urea, ether, carbonate, acetal, sulfide, phosphate, phosphonate ester, and siloxane linkages. The hollow particles may comprise from 1% to 60% of recurring structural units derived from vinylidene chloride, from 20% to 90% of recurring structural units derived from acrylonitrile and from 1% to 50% of recurring structural units derived from a (meth)acrylic monomer, the sum of the percentages (by weight) being equal to 100. The (meth)acrylic monomer is, for example, a methyl acrylate or methacrylate, and especially the methacrylate. Preferably, the particles are comprised of a polymer or copolymer of at least one monomer selected from expanded or non-expanded vinylidene chloride, acrylic, styrene, and (meth)acrylonitrile. More preferably, the particles are comprised of a copolymer of acrylonitrile and methacrylonitrile.

Particles comprised of polymers and copolymers obtained from esters, such as, for example, vinyl acetate or lactate, or acids, such as, for example, itaconic, citraconic, maleic or fumaric acids may also be used. See, in this regard, Japanese Patent Application No. JP-A-2-112304, the full disclosure of which is incorporated herein by reference.

Non-limiting examples of commercially available suitable particles are 551 DE (particle size range of approximately 30-50 .mu.m and density of approximately 42 kg/m.sup.3), 551 DE 20 (particle size range of approximately 15-25 .mu.m and density of approximately 60 kg/m.sup.3), 461 DE (particle size range of approximately 20-40 .mu.m and density 60 kg/m.sup.3), 551 DE 80 (particle size of approximately 50-80 .mu.m and density of approximately 42 kg/m.sup.3), 091 DE (particle size range of approximately 35-55 .mu.m and density of approximately 30 kg/m.sup.3), all of which are marketed under the trademark EXPANCEL.TM. by Akzo Nobel. Other examples of suitable particles for use herein are marketed under the trademarks DUALITE.RTM. and MICROPEARL.TM. series of microspheres from Pierce & Stevens Corporation. Particularly preferred hollow particles are 091 DE and 551DE 50. The hollow particles of the present invention exist in either dry or hydrated state. The aforesaid particles are nontoxic and non irritating to the skin.

Hollow particles that are useful in the invention can be prepared, for example, via the processes described in EP-56,219, EP-348,372, EP-486,080, EP-320,473, EP-112,807 and U.S. Pat. No. 3,615,972, the full disclosure of each of which is incorporated herein by reference.

Alternatively, the wall of the hollow particles useful in the present invention may be formed from an inorganic material. The inorganic material may be a silica, a soda-lime-borosilicate glass, a silica-alumina ceramic, or an alkali alumino silicate ceramic. Non-limiting examples of commercially available suitable low density, inorganic particles are H50/10,000 EPX (particle size range approximately 20-60 .mu.m), S38 (particle size range approximately 15-65 .mu.m), W-210 (particle size range approximately 1-12 .mu.m), W-410 (particle size range approximately 1-24 .mu.m), W-610 (particle size range approximately 1-40 .mu.m), G-200 (particle size range approximately 1-12 .mu.m), G-400 (particle size range approximately 1-24 .mu.m), G-600 (particle size range approximately 1-40 .mu.m), all of which are marketed under the trademarks 3M.TM. Scotchlite.TM. Glass Bubbles, 3M.TM. Zeeospheres.TM. ceramic microspheres, and 3M.TM. Z-Light Spheres.TM. Ceramic Microspheres. Also useful are Silica shells (average particle size 3 .mu.m) available from KOBO Products and LUXSIL.TM. (3-13 .mu.m mean diameter) available from PQ Corporation.

Preferably, the wall of the hollow particles useful in the invention are flexible. "Flexible", as used herein, means that the hollow particles are easy to compress. When pressure is reduced the hollow particles regain their original volume. The flexible hollow particles could alter their shape under an applied stress, or thermal expansion and contraction due to temperature change. Thus, the particles could expand upon heating.

The particles of the invention may be permeable or non-permeable. "Permeable", as used herein, means that they permit a liquid or gas to pass through them under given conditions. Preferably, a majority of the particles of the present invention will maintain their structural integrity during normal use of the composition. More preferably, substantially all of the particles maintain their structural integrity during normal use of the composition.

Prefered particles will also have physical properties which are not significantly affected by typical processing of the composition. Preferably, particles having melting points greater than about 70.degree. C. are used. Still more preferably, particles having a melting point greater than 80.degree. C. are used and most preferrably particles having melting point of greater than about 95.degree. C. are used. As used herein, melting point would refer to the temperature at which the particle transitions to a liquid or fluid state or undergoes significant deformation or physical property changes. In addition, many of the particles of present invention are cross-linked or have a cross-linked surface membrane. These particles do not exhibit a distinct melting point. Cross-linked particles are also useful as long as they are stable under the processing and storage conditions used in the making of the present compositions.

Because of the interaction between the oppositely charged species present in the emulsion and the insoluble solid particles, essentially none of the charged particles adsorbed at the interface of the internal phase and the external phase are subject to Brownian motion. Thus, the charged particles remain dispersed and are prevented from re-agglomerating in the composition. When the composition is applied to the substrate, the charged insoluble solid particles stay dispersed on the substrate. The term "essentially none" as used herein means less than about 30%, preferably less than about 10%, more preferably less than about 5%.

Brownian motion can be observed by transmitted light microscopy according to the method set forth hereinafter in the analytical methods section.

In a preferred embodiment of the present invention, essentially all of the charged species and charged particles accumulate at the interface between the internal phase and the external phase of the emulsion. As used herein, the term "essentially all" means that at least about 70%, preferably at least about 90%, more preferably at least about 95% of the charged pigment particles are accumulated at the interface of the internal phase and the external phase of the emulsion. The accumulation of insoluble solid particles at the interface between the internal phase and the external phase of the emulsion can be observed by light and electron microscopy using the method set forth hereinafter in the Analytical Methods section.

1. Charged Pigment Particles

The charged insoluble solid particles of the present invention may comprise charged pigment particles which may be organic, inorganic, or a mixture thereof. As used herein, the term "pigment" means an insoluble solid particulate material that reflects light of certain wavelengths while absorbing light of other wavelengths, including luminescent solids. Suitable charged pigment particles include organic pigments which are generally various aromatic types including azo, indigoid, triphenylmethane, anthraquinone, and xanthine dyes which are designated as D&C and FD&C blues, browns, greens, oranges, reds, yellows, etc. Organic pigments generally consist of insoluble metallic salts of certified color additives, referred to as the Lakes. Inorganic pigments include iron oxides, titanium dioxide, ultramarine and chromium or chromium hydroxide colors, and mixtures thereof. Useful pigments include, but are not limited to, those which are extended onto inert mineral (e.g., talc, calcium carbonate, clay), or treated with silicone or other coatings (e.g., to prevent pigment particles from re-agglomerating or to change the polarity (or hydrophobicity) of the pigment.

Pigments are used to impart opacity and/or color to the compositions herein. Any pigment that is generally recognized as safe (such as those listed in C.T.F.A. Cosmetic Ingredient Handbook, 3rd Ed., Cosmetic and Fragrance Association, Inc., Washington D.C. (1982), herein incorporated by reference) can be employed in the compositions herein. Useful pigments include body pigments, inorganic white pigments, inorganic colored pigments, and pearling agents. Also useful herein are pigment and/or dye encapsulates such as nanocolorants and multi-layer interference pigments, such as Sicopearls, both from BASF. Specific examples of suitable pigments include multi-layered effects pigments, lakes, toners, mica, magnesium carbonate, calcium carbonate, magnesium silicate, aluminum magnesium silicate, silica, titanium dioxide, zinc oxide, red iron oxide, yellow iron oxide, black iron oxide, ultramarine, nylon powder, polyethylene powder, methacrylate powder, polystyrene powder, silk powder, crystalline cellulose, starch, titanated mica, iron oxide titanated mica, and bismuth oxychloride. These pigments and powders can be used independently or in combination. Titanium oxide, iron oxides, lakes, toners and mixtures thereof are especially preferred pigments for use herein.

The pigments are used in a concentration sufficient to provide a pleasing color to the composition in the container in which the cosmetic is sold and to confer the desired coverage and color to the skin when applied. Determination of the specific levels and types of pigment is within the skill of the artisan. The pigments can be used as treated particles or as the raw pigments themselves.

In order to provide a natural appearance when applied to the skin, the compositions of the present invention suitable for cosmetics will usually contain from about 0.01% to about 50%, preferably from about 1% to about 30%, most preferably from about 5% to about 20%, by weight of the composition, of charged pigment particles.

The charged pigment particles of the present invention have a primary particle size ranging from about 0.01 .mu.m-200 .mu.m, preferably from about 0.1 .mu.m-100 .mu.m, and more preferably from about 0.05 .mu.m-90 .mu.m. Primary particle size of the charged pigment particles can be determined by using the ASTM Designation E-20-85 "Standard Practice for Particle Size Analysis of Particulate Substances in the Range of 0.2 to 75 Micrometers by Optical Microscopy", ASTM Volume 14.02, 1993.

The relative size of the emulsion droplet to that of the charged pigment particles is unimportant so long as the charged pigment particle is not larger than the emulsion droplet. In fact, the benefits of the invention can be achieved even when the emulsion droplets and charged pigment particles form "doublets", meaning that the emulsion droplet and the charged pigment particle are of the same approximate relative size. The preferred size ratio of emulsion droplet to charged pigment particle ranges from about 1:1 to about 50:1, preferably from about 3:1 to about 30:1, most preferably from about 5:1 to about 15:1.

As herein before described, the charged pigment particles utilized in the present invention have a charge opposite to the charge of the charged species present in the emulsion. The charge of the pigment particles can be imparted by any conventional means. In a preferred embodiment of the present invention, the pigment particles contain an ionic polymer or ionic surfactant to increase or impart a charge to the pigment particles. This embodiment of the present invention is preferred not only from the standpoint of providing the most uniform coverage of the pigment on the skin, but also from the standpoint of preventing separation or "streaking" of blends of pigments in the product and on the skin. In this embodiment of the invention, the pigment particle contains an amount of ionic polymer sufficient to cover the surface of the particle without excess in bulk.

Suitable cationic polymers and anionic polymers for use herein are described herein before in section (B) entitled "The Charged Species".

The charged pigment materials are available in essentially neat, powdered form, or predispersed in various types of carriers, including but not limited to water, organic hydrophilic diluents such as lower monovalent alcohols (e.g., C.sub.1-C.sub.4) and low molecular weight glycols and polyols, including propylene glycol, polyethylene glycol (e.g., molecular weight 200-600 g/mole), polypropylene glycol (e.g., molecular weight 425-2025 g/mole), glycerol, butylene glycol, 1,2,4-butanetriol, sorbitol esters, 1,2,6-hexanetriol, ethanol, isopropanol, sorbitol esters, butanediol, ether propanol, ethoxylated ethers, propoxylated ethers and combinations thereof. Preferably, the charged pigment materials are predispersed in water, glycerin, butylene glycol, propylene glycol, and mixtures thereof. Examples of charged particulate materials include predispersions of ammonium polyacrylate treated TiO.sub.2, butylene glycol, water, and ammonium zirconium carbonate, predispersions of chitosan (or a chitosan derivative) treated TiO.sub.2 and butylene glycol, and predispersions of ammonium polyacrylate treated TiO.sub.2, water, glycerin, and ammonium zirconium carbonate.

D. Optional Ingredients

The compositions herein may contain a wide variety of optional ingredients that perform one or more functions useful in products of the type described herein. Such optional ingredients may be found in either the internal phase or the external phase (or any other phase) of the compositions herein. The CTFA Cosmetic Ingredient Handbook, Second Edition (1992) describes a wide variety of nonlimiting cosmetic and pharmaceutical ingredients commonly used in the skin care industry, which are suitable for use in the compositions of the present invention. Examples of these ingredient classes include: abrasives, absorbents, aesthetic components such as fragrances, pigments, colorings/colorants, essential oils, skin sensates, astringents, etc.), anti-acne agents, anti-caking agents, antifoaming agents, antimicrobial agents, antioxidants, binders, biological additives, buffering agents, bulking agents, chelating agents, chemical additives, colorants, cosmetic astringents, cosmetic biocides, denaturants, drug astringents, external analgesics, enzymes, emulsifiers, film formers or materials, e.g., polymers, for aiding the film-forming properties and substantivity of the composition, opacifying agents, other pigments, pH adjusters, propellants, proteins, reducing agents, sequestrants, skin bleaching and lightening agents, skin-conditioning agents (e.g., humectants, including miscellaneous and occlusive), skin soothing and/or healing agents), skin treating agents, structuring agents, organic and inorganic sunscreen agents, thickeners, vitamins and derivatives thereof.

 

Claim 1 of 4 Claims

1. A particle stabilizing composition comprising: a. an emulsion comprising about 1% to about 99%, by weight of the emulsion, of an internal phase and from about 1% to about 99%, by weight of the emulsion, of an external phase; b. a first charged species which is selected form the group consisting of a first polyanion and a first polycation wherein said first species is present in the emulsion; and c. charged insoluble solid particles comprising titanium dioxide that are dispersed in said emulsion in the presence of a second charged species which is selected from the group consisting of a second polyanion and a second polycation; wherein the first or second polyanion is selected from the group consisting of ammonium polyacrylate, sodium polyacrylate, potassium polyacrylate, ethylene acrylic acid copolymer, and mixtures thereof, wherein the first or second polycation is selected from the group consisting of quaterniums, quaternium-80, quaternium-61, polyquaterniums, and mixtures thereof; wherein the first charged species possesses a charge opposed to that of the second charged species and of the charged insoluble solid particles and wherein essentially all of the charged species and charged insoluble solid particles accumulate at the interface of the emulsion and wherein Brownian motion is not exhibited by the insoluble solid particles.
 

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