Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Patent
1995-08-09
1997-10-07
Gardner, Sallie M.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
424 7803, 424 7012, 514938, A61K 700, A61K 748
Patent
active
056745095
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/US94/01134 filed Feb. 1, 1994.
TECHNICAL FIELD
The present invention relates to cosmetic compositions. In particular it relates to cosmetic compositions in the form of emulsions or lotions which provide improved moisturization, skin feel and skin care benefits and reduced greasiness, together with excellent rub-in and absorption characteristics. The compositions also display excellent stability characteristics at normal and elevated temperatures.
BACKGROUND OF THE INVENTION
Skin is made up of several layers of cells which coat and protect the keratin and collagen fibrous proteins that form the skeleton of its structure. The outermost of these layers, referred to as the stratum corneum, is known to be composed of 25 nm protein bundles surrounded by 8 nm thick layers. Anionic surfactants and organic solvents typically penetrate the stratum corneum membrane and, by delipidization (i.e. removal of the lipids from the stratum corneum), destroy its integrity. This destruction of the skin surface topography leads to a rough feel and may eventually permit the surfactant. or solvent to interact with the keratin, creating irritation.
It is now recognised that maintaining the proper water gradient across the stratum corneum is important to its functionality. Most of this water, which is sometimes considered to be the stratum corneum's plasticizer, comes from inside the body. If the humidity is too low, such as in a cold climate, insufficient water remains in the outer layers of the stratum corneum to properly plasticize the tissue, and the skin begins to scale and becomes itchy. Skin permeability is also decreased somewhat when there is inadequate water across the stratum corneum. On the other hand, too much water on the outside of the skin causes the stratum corneum to ultimately sorb three to five times its own weight of bound water. This swells and puckers the skin and results in approximately a two to three fold increase in the permeability of the skin to water and other polar molecules.
Thus, a need exists for compositions which will assist the stratum corneum in maintaining its barrier and water-retention functions at optimum performance in spite of deleterious interactions which the skin may encounter in washing, work, and recreation.
Conventional cosmetic cream and lotion compositions as described, for example, in Sagarin, Cosmetics Science and Technology, 2nd Edition, Vol. I, Wiley Interscience (1972) and Encyclopaedia of Chemical Technology, Third Edition, Volume 7 are known to provide varying degrees of emolliency, barrier and water-retention (moisturizing) benefits. However, they can also suffer serious negatives in terms of skin feel (i.e. they often feel very greasy on the skin) as well as having poor rub-in, absorption and residue characteristics.
The present invention therefore provides skin-care cosmetic compositions which provide improvements in moisturization, absorption, skin feel and skin care characteristics and which in particular provide improved short and longer term moisturizing effectiveness, while at the same time reducing stickiness and avoiding a greasy feel on the skin. The compositions also display excellent stability characteristics at both normal and elevated temperatures.
SUMMARY OF THE INVENTION
Accordingly, in one aspect of the present invention, there is provided a skin care composition in the form of an oil-in-water dispersion comprising one or more distinct oil phases, wherein the primary oil phase is present in a level of from about 4% to about 16% by weight and wherein the composition incorporates from about 2% to about 10% of an emulsifier capable of forming liquid crystals in water. Preferably, the emulsifier is a fatty acid ester blend based on a mixture of sorbitan fatty acid ester and sucrose fatty acid ester, and wherein the ratio of primary oil phase to fatty acid ester emulsifier is in the range from about 6:1 to about 1:1.
The compositions of this aspect of the present invention take the form of an oil-in-water emulsion or di
REFERENCES:
patent: 3919430 (1975-11-01), Siegel
patent: 4776976 (1988-10-01), Nakamura
patent: 5013715 (1991-05-01), Mori et al.
patent: 5106609 (1992-04-01), Bolich, Jr. et al.
Courpron Elise
Date Robert Francis
Nawaz Zahid
Rolls Richard George A.
Dabbiere David K.
Gardner Sallie M.
Reed T. David
Sabatelli Anthony D.
The Procter & Gamble & Company
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