WO2000047167A1

WO2000047167A1 - Cosmetic and pharmaceutical compositions containing crystalline color system and method of preparing same

Info

Publication number: WO2000047167A1
Application number: PCT/US2000/001354
Authority: WO
Inventors: Konstantinos M. Lahanas; Gheorghe Cioca
Original assignee: Color Access Inc
Current assignee: Color Access Inc
Priority date: 1999-02-09
Filing date: 2000-01-19
Publication date: 2000-08-17
Anticipated expiration: 2001-08-09
Also published as: AU2416400A

Abstract

The present invention relates to cosmetic or pharmaceutical compositions containing a coloring system comprising colloidal crystalline arrays in a medium. The invention also includes a method for preparing a cosmetic or pharmaceutical composition by adding colloidal crystalline arrays to a medium. The coloring systems produce clear color, especially iridescent color, without adding pigments or dyes. The color is long lasting and can be observed at any angle of view of the composition.

Description

AND^MMETH0^^ CONTAINING CRYSTALLINE COLOR SYSTEM

Field of the Invention The present invention relates to useful cosmetic or pharmaceutical compositions having color without the use of traditional pigments or dyes. In particular, the invention relates to a composition containing crystalline colloidal arrays suspended m an aqueous medium which are capable of producing iridescent colors.

Background of the Invention

The ability to achieve color m a cosmetic composition has been traditionally accomplished by the addition of pigments, dyes, lakes and other similar colorants. However, due to the tendency of these additives to drag or cake on the skin, they can feel unpleasant when applied. Additionally, these coloπng substances are not always easy to formulate into cosmetic compositions as, for example, inorganic pigments are larger sized particles that tend to agglomerate (i.e., they do not readily stay uniformly dispersed but rather precipitate or settle out), and organic dyes, while they are water soluble, tend to fade or shift in color. Therefore, there remains a need to achieve color in a composition, especially a cosmetic composition, that is simple to formulate, and provides and retains the desired color Attempts to provide colored compositions without adding pigments, dyes or lakes have been made using liquid crystals. Liquid crystals are a well known phenomenon. They exist as an intermediate phase between the liquid phase and the solid phase. Certain organic compounds are capable of existing as liquid crystals because of their rod-like crystalline shape and the attractive forces of the molecules There are two types of liquid crystal mesophases. One is the smectic mesophase and the other is the nematic mesophase On the one hand, the smectic mesophase is one which constitutes a long range ordering that is of a substantially lamellar type (i.e., they are arranged in raft like layers). On the other hand, the nematic mesophase is ordered substantially linearly (i.e., the molecules are lined up whereby the long axes of the molecules are parallel) Molecules of liquid crystals are arranged in a periodic fashion in at least one direction. However, there are disadvantages associated with the use of this type of liquid crystals, depending on the structure of the liquid crystal, in that their chemical stability, temperature and light stability, especially UV light stability, is relatively low. Further, liquid crystals are limited to use m hydrophilic systems because they suspend better in these systems. In hydrophobic systems, the crystals dissolve and their structure breaks down

A number of prior art methods and compositions have been developed which attempt to impart color by means of light reflected by liquid crystals, as disclosed in U.S. Patent Nos 5,362,315, 5,188,815, 4,839,163, and 4,301,023. However, some systems still include an additional dye or traditional colorant. Still with other systems, dilution is not possible without negatively effecting the claπty of the color because liquid crystals are suspended in hydrophilic systems. The system has to be fixed or frozen m a film to maintain stability of the system, otherwise the color of these systems is hazy and fuzzy Liquid crystals are visually less appealing when they are dispersed in a medium and do not feel good on the skin when neat. Therefore, an effective stable colorant is needed that can be prepared in a free flowing aqueous system, is observable from any angle of view, and has an improved temperature stability. The compositions of the present invention meet these needs and offer enhanced color claπty.

SUMMARY OF THE INVENTION

The present invention provides cosmetic or pharmaceutical compositions for topical application to the skin compπsmg a coloπng system which compπses a colloidal crystalline array (hereinafter referred to as "CCAs") m an aqueous medium The color of the composition is produced by light directed at and diffracted by the arrays of the coloπng system. The invention also provides for a method for preparing a cosmetic or pharmaceutical composition having a coloring system compnsmg adding CCAs to a cosmetically or pharmaceutically acceptable aqueous medium

DETAILED DESCRIPTION OF THE INVENTION

Adding color to cosmetic or pharmaceutical compositions is desirable because a consumer may find it more pleasant and appealing to use a product that has a certain color. The present invention comprises a coloring system for cosmetic or pharmaceutical compositions using a system of colloidal crystalline arrays to advantageously provide rainbow-like appealing colors. The synthesis of monodisperse spherical particles and CCAs composed thereof which produce an mdescent color is known and described in, for example, U.S. Patent Nos.4,627,689, 4,632,517, and 5,452,123, the contents of which are incorporated herein by reference. In these patents, a crystalline colloidal narrow band radiation filter and methods for making switching devices and related devices using CCAs are disclosed. Although, the ability of CCAs to produce an iridescent color is known, a water based cosmetic or pharmaceutical composition colored by a coloπng system of CCAs has not previously been suggested in the prior art. In addition, particular cosmetic materials have been found that do not interfere with the structure of the CCA. The color of the CCA coloring system is produced as light travels through and is diffracted by the crystalline structure of the CCA. The CCAs are composed of spherical particles that are capable of self-assembly. The uniform particle size and surface charge density of the spheres cause coulombic electrostatic repulsive forces between them and allow the spheres to "self-assemble" into crystalline lattice structures which efficiently diffract light meeting the Bragg condition. See Asher, S.A., et al, "Novel Optically Responsive and

Diffracting Materials Derivedfrom Crystalline Colloidal Array Self-Assembly", Chapter 33, ACS Symposium Ser., pps. 495-506 (1997); incorporated herein by reference. Bragg's law is represented by the equation, mλ₀=2nd sin θ; where, m is an integer representing the number of planar layers of the CCA, λ₀ is the wavelength of light in a vacuum, n is the refractive index of the system, d is the mterplane spacing, and θ is the Bragg angle. Bragg diffraction of light occurs from planes of closely-packed spheres in succession and m parallel alignment to a surface. See Tse, Albert S., Wu, Zhijun, and Asher, Sanford A., "Synthesis ofDyedMonodisperse Polyfmethyl methacrylate) Colloids for the Preparation ofSubmicron Periodic Light- Absorbing Arrays ", Macromolecules 28, pps.6533-6538 (1995); incorporated herein by reference.

The spheres arrange themselves in an order such that there are at least two planes running through the array. Each of the planes is parallel to one another and has an angle incident thereto. The distance between the planes is determined by the number density of the particles, the particle size and the surface charge. Because the spacing of CCAs is similar to the wavelength of visible and near-LR light, strong Bragg diffraction of light occurs as it travels through the CCAs. The creation of color, by the self-assembly of the spheres into CCAs, is partially dependent on the concentration density of the spheres.

The compositions of the present invention can produce any color. For the purposes of the present invention, the use of the term "color" herein is not only understood to mean the color impression of the wavelength region of visible light perceivable by the human eye, but also the color impression of the adjacent UV and LR wavelength regions not perceivable by the human eye but measurable by known instruments, such as UV and LR spectrometers or goniometers. In a preferred embodiment of the present invention, the color is iridescent like a precious opal and the color is clear, sharp and shiny The production of color based on the number density ranges from the red region through to the blue region of the spectrum. At one end of the spectrum, for example, a lower number density for a particular particle size and composition may produce color in the red region, while at the other end of the spectrum, a higher number density may produce color m the blue region. The colors of mdigo and violet may also be achieved with a higher number density.

Accordingly, the number density of the spheres is about 1 to about 95 percent of the composition, preferably from about 5 to about 50 percent, more preferably it is from about 10 to about 25 percent. An advantage of the present invention is the ability to produce a dilute concentration of spheres capable of giving off a clear and stable rainbow type of color in a water based cosmetic or pharmaceutical composition.

The spheres can be natural or treated cross linked materials or other mateπals having a refractive index value of greater than about 1.0, preferably between 1.5 and 3.0. The spheres of the CCAs are formed by treating at least one precursor and a surfactant. The general process involves emulsion polymerization or condensation of the precursor and the surfactant to form spherical particles of monodisperse uniform particle size and uniform surface charge density. Known polymeπzation techniques such as, for example, dispersion or emulsion polymeπzation or condensation processes are described m Bhattacharyya, Bhupati and Halpern, B. David, "Application of Monodisperse Functional and Fluorescent Latex Particles", Polymer News 4, pps. 107-114 (1977); incorporated herein by reference. Preparation of CCAs is also described, in U.S. Patent No. 4,632,517.

Specifically, the spherical particles of CCAs can be formed by combining the precursor and the surfactant with deiomzed, doubly distilled water and allowing it to polymeπze in a water bath until crystal formation is complete, usually about 4 to 8 hours. Crystal formation is verified by the appearance of an iridescent color. The amount and type of precursor, and the amount of surfactant are factors which determine the concentration density of the spheres and consequently, the self-assembly of the spheres into CCAs.

In principle, any one or more organic or inorganic precursors which are capable of combining to form spherical colloidal particles that have a monodisperse uniform particle size and uniform surface charge density can be used in the present invention. The term "monodisperse" as used herein descπbes a particle size distribution of the spheres which is gaussian and has a low standard deviation (i.e., standard deviation of less than 5 percent of the mean). The precursor can be any material capable of assembling into an ordered array dispersed throughout a solvent. Preferably, the precursors are selected from the group consisting of methacryhc acid and derivatives thereof such as, for example, polymethylmethacrylate (hereinafter referred to as "PMMA"), silicon alkoxides and hydroxides such as, for example, silica (e.g. silicon dioxide), aluminum alkoxides such as, for example, aluminum dioxide, polytetrafluoroethylene, styrene and polymers thereof such as for example, polystyrene, titanium alkoxides such as for example, titania, and divmylbenzene. Such starting mateπals are disclosed, for example, m U.S. Patent No. 5,452,123. More preferably, however, the precursor is PMMA, polystyrene, or silica. See Tse et al., supra. Most preferably, the precursor is polystyrene. The precursor is combined with the surfactant, the amount of which can vary depending on the desired particle size of the spheres. In general, there is an inverse relationship between the amount of surfactant and the size of the spheres (i.e., lower amounts of surfactant produce larger sized spherical particles.) Preferably, the amount of surfactant is about 0.01 to about 10 percent of the weight of the composition. The surfactant has an HLB of greater than about 12. Examples of suitable surfactants include but are not limited to M A-

80 which is sodium dι(l,3-dιmethylbutyl) sulfosuccmate in isopropanol and water, sodium dodecylsulfate, nonoxynol series, octoxynol series, and other surfactants which can be found for example in the CTFA International Dictionary of Cosmetic Ingredients.

The spheres have an average particle size of about 100 to about 1500 nm in diameter. More preferably, the spheres have an average particle size of about 1000 to about 1300 nm

The variation in particle size should preferably be less than about 5 percent of the mean. The uniform particle size promotes the equalization of the repulsive forces between the spheres and therefore, assists the spheres in the process of self-assembly.

The order in which the spheres of a CCA arrange themselves is based on the repulsive forces between them. The spheres have a highly uniform surface charge density.

They strongly electrostatically repel each other when the space between them is within a Debye layer length (<1 μm). The surface charge density is an estimation of the ionized H⁺ or OH^" counter-ions This estimation can be made using potentiometπc or conductometπc titration methods known in the art. In a preferred embodiment of the present invention, the spheres have a surface charge density of about 0.5 to about 30 μC/cm², preferably about 1 to about 5 μC/cm².

The surface charge density is quantified by the equation, σ₀ = N_sev; where, σ₀ is the surface charge density, N_s is the number of charged sites per unit area, v is their valency, and e is the fundamental charge on the electron (1.6 x 10^"19 coulomb). The H^" or OH ions are predominantly found on the surface of the sphere on what is commonly referred to as the electrical double layer. Each of the spheres can have either a smooth or a hairy charged surface. See Ottewill, Ronald H., "Colloidal Properties of Latex Particles ", Scientific Methods for the Study of Polymer Colloids and Their Applications. 129, 130 (1990); incorporated herein by reference. The electrical double layer affects the repulsive forces between the spheres and thus, affects their process of self-assembly.

The counter-ion cloud of each sphere surrounds the electrical double layer at the surface of the sphere. When spheres are in close proximity to one another, there is a slight overlap of the counter-ion clouds associated with each of the spheres. Immediately, the spheres repel each other due to the repulsive forces caused by the counter-ions. Scientific

Methods for the Study of Polymer Colloids and Their Applications, supra, at 132. The CCA formed by the self-assembly of the spheres is a result of the repulsive forces between them. When the energy is greater than about kT, where k is the Boltzmann constant and T is the absolute temperature, the spheres are able to self-assemble. A highly pure medium is necessary to prevent mterfenng with the surface charge density of the spheres and thus, disrupting the process of self-assembly into CCAs. The term "pure" refers to a substantial lack of impurities m the medium in the form of ions and can be expressed in terms of conductivity of the medium. In other words, a highly pure medium has a low ionic strength due to a low level of ionic impuπties. If the ionic strength is too high, flocculation may occur and the color dissipates. This phenomenon can occur locally within the medium or throughout the medium. Thus, in a preferred embodiment, the medium has a relatively low ionic strength. Preferably, the medium has a conductometπc reading of less than about 2.5 μΩ^"1 indicating that the ionic purity of the medium is sufficient for CCAs to form. More preferably, the medium is non-ionic. The spheres are dispersed m an aqueous medium which can include any low ionic or non-ionic solvent that is miscible in water and is stable so that it does not produce degradant ions at a later time. Thus, the medium is predominantly aqueous and can also include solvents such as, for example, hydroalcohol, glyceπn, and combinations thereof. Examples of acceptable hydroalcohols include, but are not limited to ethanol, propanol, or glycols such as polyethylene glycol. Preferably, the medium is aqueous, however, if the medium is partially nonaqueous, preferably the nonaqueous portion is present in an amount no greater than about 50 percent, more preferably it is no greater than about 30 percent.

Co-polymeπzation treatment of the spherical particles can improve the self-assembly of the spheres. Further treatment of the spheres after initial polymerization can render the surface charge density more uniform. Even though the polymerized spherical particles may have a natural surface charge density, co-polymeπzation of the spheres enhances the uniformity of the surface charge density Types of co-polymeπzation treatment can involve, for example, adding an anionic comonomer The aniomc property of the comonomer causes the surface charge density of the particles to increase. In turn, the increased surface charge density causes an intensification of the electric forces which form and maintain the self- assembly of the spheres into the CCA, thereby strengthening the CCA. Comonomers with anionic groups for copolymeπzation include for example, but are not limited to, the 1- sodium, 1 -allyloxy-2-hydroxypropane sulfonate (COPS- 1 ), sodium salt of styrene sulfonate, 2-acrylamιdo-2 -methyl-propane sulfonate, 3-sulfopropyl methacrylate potassium salt, and vinyl sulfonate.

Post-polymeπzation treatment, such as for example, deiomzation techniques, can reduce the ionic strength of the medium Examples of this treatment include but are not limited to dialysis, centπfugation, puπfication using an ion exchange column, or any other similar apparatus or method appropriate for removing ions or surfactant from the system. Any ions remaining, after purification, are most likely part of the electrical double layer (i.e., ions distributed close to the surface of the sphere and part of the counter ionic cloud which surrounds the sphere.) More than one post-polymerization technique can be applied. While it is best to perform each of the techniques separately, the post-polymeπzation treatment can also include a combination of the techniques mentioned above (i.e., addition of the anionic comonomer and purification) to improve the surface charge density of the particles and to reduce the ionic strength of the medium.

It is withm the scope of the present invention for the spheres to arrange themselves into any crystal structure that may be formed depending on the specific properties of the precursor and the surfactant, such as for example, the 14 Bravais lattices. However, preferably, the spheres arrange themselves into either a face centered cubic arrangement or a body centered cubic arrangement. Thus, m one embodiment, the CCA has a face centered cubic arrangement. This arrangement represents the lowest energy state of the coloring system. In another embodiment, the CCA has a body centered cubic arrangement. Although one of the benefits of the present invention is the ability to achieve long lasting and observable color of enhanced clarity at all angles of view of the composition, it may be desirable to add other organic and inorganic pigments and dyes to the composition. The addition of such pigments and dyes is limited, however, to those that have a low ionic strength and that will not interfere with the formation of CCAs or their continued stability once formed.

The compositions of the present invention can be m the form of a solution, colloidal dispersion, emulsion, suspension, cream, lotion, gel, foam, or mousse which is sufficiently clear to permit the appearance of color in the product. If the product is in the form of an emulsion, the CCA can be m the water phase of the emulsion as long as the volume of the water phase is sufficiently large to encompass the area of the CCA. The compositions of the present invention can be formulated with a variety of cosmetically and/or pharmaceutically acceptable earners. The term "pharmaceutically and/or cosmetically acceptable carrier" refers to a vehicle, for either pharmaceutical or cosmetic use, which vehicle holds the compositions of the present invention and which will not cause harm to humans or other recipient organisms. As used herein, "pharmaceutical" or "cosmetic" will be understood to encompass both human and animal pharmaceuticals or cosmetics. The earner may be in any form appropriate to the function of the mode of delivery and that does not interfere with the stability of the CCAs.

As noted above, the compositions of the present invention can also be used pharmaceutically, and therefore may also comprise useful active ingredients, for the purposes of therapeutic treatment. Useful active ingredients include, but are not limited to antioxidants, antimicrobials, sunscreens, analgesics, anesthetics, anti-acne agents, antidandruff agents, antidermatitis agents, antipruntic agents, anti-inflammatory agents, antihyperkeratolytic agents, anti-dry skin agents, antiperspirants, antipsoπatic agents, antiseborrheic agents, hair conditioners and hair treatment agents, antiaging agents, antiwnnkle agents, antihistamine agents, skin lightening agents, depigmenting agents, wound- healing agents, vitamins, corticosteroids, tanning agents, or hormones. The inclusion of the active m the formulation is limited only by its solubility and/or stability m the aqueous medium (i.e., requiring low ionic strength) and its compatibility with the CCAs.

In addition, the compositions may also compπse additional preservatives, fragrances, emollients, antiseptics, stabilizers, pigments, dyes, humectants, and propellants, as well as other classes of mateπals the presence of which m the compositions may be cosmetically, pharmaceutically, or otherwise desired. Such components can be found in the CTFA

International Cosmetics Ingredients Dictionary. Preservatives employed, may be m an amount of from about 0.01 to about 2 percent, preferably from about 0.01 to about 1 percent, of the formula weight. Examples of suitable preservatives are BHA, BHT, propyl paraben, butyl paraben or methyl paraben or an isomer, homolog, analog or derivative thereof. The present invention is further illustrated by the following non-limiting examples. EXAMPLE I COLLOIDAL CRYSTALLINE ARRAY ("CCA")

Methylmethacrylic acid (MMA) and divinylbenzene (DVB) are mixed at room temperature. A main vessel holding 230 g of water is heated to 80° C. While maintaining the temperature of 80° C, add sodium dodecylsulfate to the vessel. Predissolve the sodium persulfate in the remaining water and add it to the main vessel. Add mixture of MMA and DVB to the vessel Next, add COPS-1 to the vessel. Reflux the mixture for about 4 hours at 80° C. Sample is then dialyzed and treated with a mixed bed ion exchange resin to remove any remaining ions as part of the post-polymerization dialysis treatment. Dialysis is continued for 2 to 3 weeks during which time, water is changed 2 times a day.

Silica CCAs are commercially available from Ikeda Corporation of America, Island Park, NY, as Opalesque 1015 and 1030.

EXAMPLE II

LIQUID TONER WITH POLYMETHYLMETHACRYLATE (PMMA) CCA

Ingredient Percent

Water 48.90

Witch hazel 5.00

Isopropanol 10.00

Allantoin 0 10

Trehalose 1.00

1,3 Buty1ene glycol 5.00

PMMA CCA 30.00

EXAMPLE πi

LIQUID TONER WITH SILICA CCA

Ingredient Percent

Water 53 90

Witch hazel 5 00

Isopropanol 10 00

Allantoin 0 10

Trehalose 1 00

1 ,3 Butylene glycol 5 00

Silica CCA 25 00

Claims

What we claim is:

1. A cosmetic or pharmaceutical composition comprising a coloring system which comprises colloidal crystalline arrays in a pharmaceutically or cosmetically acceptable aqueous medium, said arrays being formed of spheres having a particle size of about 100 to about 1500 nm.

2. The composition of claim 1 wherein said spheres have a monodisperse uniform particle size and uniform surface charge density arranged in an order having at least two planes, each of said planes being parallel to one another and having an angle incident thereto.

3. The composition of claim 2 further defined by said medium having an ionic strength of about 2.5 μΩ^"' or less.

4. The composition of claim 2 wherein said spheres have a surface charge density of about 0.5 to about 30 μC/cm².

5. The composition of claim 4 wherein said spheres are present in an amount of about 1 to about 95 percent by weight of the composition.

6. The composition of claim 5 wherein said spheres have a refractive index value of greater than about 1.0.

7. The composition of claim 6 further defined by said spheres being arranged in a face centered cube.

8. The composition of claim 6 further defined by said spheres being arranged in a body centered cube.

9. The composition of claim 1 wherein said spheres being prepared by polymerization of at least one precursor and a surfactant.

10. The composition of claim 9 wherein said precursor is selected from the group consisting of silicon alkoxides and hydroxides, methacrylic acids, titanium alkoxides, aluminum alkoxides, polytetrafluoroethylene polymers, divinylbenzene, styrene polymers, and derivatives thereof.

1 1. The composition of claim 10 wherein said precursor is polystyrene.

12. The composition of claim 9 wherein said surfactant is present in an amount of about 0.01 to about 10 percent by weight of the composition.

13. The composition of claim 12 wherein said surfactant is selected from the group consisting of sodium di( 1 ,3-dimethylbutyl) sulfosuccinate, sodium dodecylsulfate, nonoxynol series, and octoxynol series.

14. The composition of claim 1 which is in the form of a solution, colloidal dispersion, emulsion, suspension, cream, lotion, gel, foam, or mousse being sufficiently clear to permit the appearance of color.

15. The composition of claim 14 which is a toner.

16. A cosmetic or pharmaceutical composition comprising a coloring system which comprises colloidal crystalline arrays in a pharmaceutically or cosmetically acceptable aqueous medium, said arrays being formed of spheres having a particle size of about 100 to about 1500 nm, said spheres comprising silica.

17. A cosmetic or pharmaceutical composition comprising a coloring system which comprises colloidal crystalline arrays in a pharmaceutically or cosmetically acceptable aqueous medium, said arrays being formed of spheres having a particle size of about 100 to about 1500 nm, said spheres comprising polystyrene.

18. A method for preparing a cosmetic or pharmaceutical composition comprising a coloring system which comprises adding colloidal crystalline arrays to a cosmetically or pharmaceuticalK acceptable aqueous medium.

19. A cosmetic or pharmaceutical composition comprising a coloring system which comprises colloidal crystalline arrays in a pharmaceutically or cosmetically acceptable aqueous medium having an ionic strength of about 2.5 μΩ^"1 or less, wherein said arrays are formed of spheres prepared by polymerization of at least one precursor and a surfactant, wherein said precursor is selected from the group consisting of silicon alkoxides and hydroxides, methacrylic acids, titanium alkoxides, aluminum alkoxides, polytetrafuoroethylene polymers, divinylbenzene, styrene polymers, and derivatives thereof, and said surfactant is selected from the group consisting of sodium di( 1 ,3-dimethylbutyl) sulfosuccinate, sodium dodecylsulfate. nonoxynol series, and octoxynol series, and said spheres having a refractive index value of greater than about 1.0.