Drug – bio-affecting and body treating compositions – Live skin colorant containing – Lip
Reexamination Certificate
1993-09-07
2001-12-04
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Live skin colorant containing
Lip
C424S063000, C424S450000
Reexamination Certificate
active
06325995
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to lipstick compositions which comprise thermodynamically stable association structures which are used to deliver polar moisturizing agents through a nonpolar (lipophilic) matrix. The invention provides for a lipstick with optimum stability of the polar moisturizing agents, while also providing moisturizing benefits to the lips.
BACKGROUND OF THE INVENTION
Lipsticks are primarily composed of hydrocarbon waxes, esters of fatty acids or alcohols and oils. Water and other polar solvents, such as glycerine and propylene glycol, which can provide moisturization benefits are not soluble in this lipophilic matrix. As a result, various emulsifiers have been added to lipsticks in an attempt to emulsify the moisturizers/polar solvents. There has been partial success in this area by utilizing the emulsifiers and moisturizers/polar solvents at low concentrations. However, the moisturizers/polar solvents may separate from the lipstick causing it to look wet and messy. This is unacceptable to the consumer.
Thus a need exists to provide a lipstick which binds thermodynamically the moisturizers/polar solvents (discontinuous phase) and deliver them in a predominately nonpolar lipophilic matrix (continuous phase). Further, there is a need to provide a means of thermodynamically binding the moisturizers/polar solvents in such a way which will allow incorporation of high levels of the moisturizing agents while exhibiting overall excellent stability and providing good feel properties.
It has been discovered that association structures consisting essentially of a surfactant or mixture of surfactants having a Krafft point at or below about ambient temperature (about 20° C.) and a moisturizer/polar solvent can thermodynamically bind the moisturizer/polar solvent and homogeneously absorb in the lipophilic matrix while providing good feel and a means of delivering the moisturizing agents to the lips. Thus, the association structures of this invention can be used to deliver the moisturizers/polar solvents without syneresis, the separation of the hydrophilic materials. It has been discovered that upon application to the lips the preferred association structures of the present invention form a film on the lips which can act as a reservoir for the moisturizer/polar solvent.
It is particularly desirable that the lipsticks comprising said association structures be made from ingredients that are presently used and approved for use in edible product applications and for applying to the skin. It is an object of this invention to provide a delivery system for moisturizers/polar solvents through the nonpolar matrix of the lipstick while providing good feel. It is another object of this invention to provide a lipstick composition which can be easily molded yet contain high levels of moisturizers.
Sweating, the excretion of oil on the surface of a lipstick, is a common problem. Lipsticks are a complex mixture of solid, semi-solid and liquid lipids. Wax networks suspend the oils present in the lipstick. Sweating occurs due to the inferior oil-binding capacity of the wax network and/or to a high oil content causing supersaturation. The phenomenon can occur in any climate or temperature; although, it is more apt to occur in sub-tropical and tropical climates.
In most cases, castor oil has been identified as the excreted oil. A major ingredient of most lipstick formulations, castor oil can generally comprise up to forty percent of lipsticks. The high percentage of castor oil is primarily due to its unique properties as a wetting agent for pigments. Monodispersions of pigments are commonly made in slurries comprising from about 30% to about 40% pigments and from about 60% to about 70% castor oil.
It is an object of this invention to provide a preferred lipstick composition of the present invention which is substantially free of castor oil. It is an object that the lipstick be castor oil sweat resistant or castor oil sweat free. An added benefit to removing the castor oil is the removal of the castor oil odor.
It has been discovered that the association structures, preferably lamellar liquid crystals (neat phase), can be used to deliver moisturizing agents in lipsticks which are substantially free of castor oil. It has been found that removal of the castor oil, typically present in the range of from about 30% to about 50% of the lipstick compositions, allows for optimization of emollients; thus, providing for a more consumer acceptable feel, such as less tackiness, and moisturizing benefits by utilizing more lubricious emollients.
All percentages and ratios stated herein are by weight unless otherwise indicated.
SUMMARY OF THE INVENTION
The present invention relates to lipstick compositions which comprise association structures which are used to deliver moisturizing agents/polar solvents into a non-polar/lipophilic medium in a thermodynamically stable way. A method of making the lipstick is also disclosed.
The lipstick compositions comprise:
(a) from about 5% to about 90%, by weight, of wax;
(b) from about 1% to about 90%, by weight, of an emollient component comprising from 0% to about 100%, by weight, of oil liquid at ambient temperature;
(c) from about 0.1 to about 80%, by weight, of an association structure consisting essentially of:
(1) from about 3% to about 96%, by weight, of polar solvent; and
(2) from about 4% to about 97% by weight, of surfactant having a Krafft point at or below about ambient temperature; and
(d) from 0% to about 35%, on an anhydrous basis, of color;
Preferred lipstick compositions are substantially free of castor oil, contain a coupling agent, and/or have compatible solubilities for wax and oil components. These lipstick compositions provide moisturizing, long wear and good feel properties.
Without intending to necessarily limit the scope of the invention, it is believed that the association structures adsorb onto solid/liquid, or liquid/liquid interfaces in heterogeneous systems such as lipsticks and other cosmetic sticks. An association structure, preferably a liquid crystalline lamellar phase, forms in the continuous phase. These association structures are able to flow under shear and act as lubricants between the different components of the heterogeneous systems such as the solids and other materials in the product. They also stabilize the actives by entrapping the liquid, solids particles or droplets in their matrix and preventing them from flocculating and further coalescing.
DETAILED DESCRIPTION OF THE INVENTION
Definition
As used herein, the term “solid material” refers to any solid lipstick ingredient capable of adsorbing the association structures. Solids include waxes, solid fats, waxy emulsifiers or pigments commonly used in lipsticks.
As used herein, “color(s)” includes pigments, dyes, colors, lakes, and pearl. Colors are measured on an anhydrous weight basis.
As used herein, the term “lecithin” refers to a material which is a phosphatide. Naturally occurring or synthetic phosphatides can be used. Phosphatidylcholine or lecithin is a glycerine esterified with a choline ester of phosphoric acid and two fatty acids, usually a long chain saturated or unsaturated fatty acid, having 16-20 carbons and up to 4 double bonds. Other phosphatides capable of forming association structures, preferably lamellar or hexagonal liquid crystals, can be used in place of the lecithin or in combination with it. Other phosphatides are glycerol esters with two fatty acids as in the lecithin, but the choline is replaced by ethanolamine (a cephalin), or serine (a-aminopropanoic acid; phosphatidyl serine) or an inositol (phosphatidyl inositol).
As used herein, the term “surfactant” refers to a low molecular weight or monomer non-polymeric organic compound amphiphilic in nature, i.e., it has hydrophilic and hydrophobic groups and exhibits a marked tendency to adsorb on a surface or interface and lower the surface tension. Surfactants or emulsifiers are divided into nonionic (no charge), anionic (negative charge), cationic (positive charge) and amphoteric (both
El-Nokaly Magda
Leatherbury Neil Campbell
Vatter Michael L.
Walling David William
Allen George W.
Howard S.
Howell John M.
Kendall Dara M.
Page Thurman K.
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