Drug – bio-affecting and body treating compositions – Live hair or scalp treating compositions – Polymer containing
Reexamination Certificate
1999-10-22
2001-09-18
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Live hair or scalp treating compositions
Polymer containing
C424S070100, C424S070110, C424S070210, C424S070190, C424S070220, C424S070310, C424S401000
Reexamination Certificate
active
06290943
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to liquid surfactant composition, e.g., liquid shower gels or liquid shampoos, comprising multiple emulsions. In particular, this invention relates to such compositions which may comprise high levels of surfactants while the multiple emulsion is nonetheless stable.
BACKGROUND OF THE INVENTION
Multiple emulsion systems (broadly defined as systems in which water/oil and oil/water emulsion co-exist) are very valuable because these permit incorporation and enhanced delivery of benefit agents. Thus, these multiple emulsions have been used for many years, for example, in cosmetic and pharmaceutical areas to deliver cosmetic or pharmacological benefit agents (see for Example, U.S. Pat. No. 5,306,498 to Vesperini; or U.S. Pat. No. 5,567,426 to Nadaud et al.).
In general, however, as the level of cleansing surfactant (e.g., having high HLB, e.g., HLB greater than 10, preferably greater than 12) in such multiple emulsion systems is increased, the emulsions become less and less stable. Thus, for example, the level of cleansing surfactant in almost all the cosmetic and pharmaceutical art referred to above is below 5% by wt. of the compositions.
In U.S. Pat. No. 5,656,280 to Herb et al., and U.S. Pat. No. 5,589,177 to Herb et al. as well as in equivalent EP 717,978 and EP 715,842, both assigned to Helene Curtis, there is disclosed the stabilization of multiple emulsions in compositions containing high levels of conditioning surfactant. In these references, however, the stable multiple emulsion composition comprises surfactants (i.e., the conditioning surfactants of that invention) which must form stabilizing liquid crystals, i.e., lamellar liquid crystals. Those compositions described in the Herb patent where the surfactants formed an isotropic phase (for example, Example 29 at column 29 of U.S. Pat. No. 5,589,177 at lines 30-44) were unstable (see column 34, where stability of Example 29 is only 5 minutes). By contrast, the surfactant phase of the present invention is an isotropic surfactant phase, yet the multiple emulsion does not break into a simple emulsion when evaluated at room temperature for at least 2 weeks, preferably greater than 4 weeks, more preferably greater than 8 weeks, when measured at a temperature of about 25° C.
Compositions comprising isotropic surfactant phases are advantageous over compositions comprising lamellar liquid crystal phase at least because (1) they can be formed using a much wider range of surfactant; and (2) they provide improved foam/lather.
Accordingly, it is an object of the invention to provide a surfactant phase which is not constrained in that it has to be lamellar phase.
It is another object of the invention to provide a surfactant phase (which is an isotropic phase) which contains high levels of surfactant and yet does not destabilize the multiple emulsion.
BRIEF SUMMARY OF THE INVENTION
Unexpectedly, applicants have now found that it is possible to obtain multiple emulsion systems which comprise high levels of surfactant forming an isotropic phase and whereby the multiple emulsion can deliver desirable benefit agent (e.g., in the internal oil phase) while simultaneously maintaining the stability of the multiple emulsion. In previous art it has been difficult or impossible to make stable multiple emulsions in the presence of high levels of surfactant which form an isotropic phase. In preferred embodiments, the surfactant system comprises mixtures of anionic and amphoteric surfactants and levels of surfactant are greater than about 10.5% of total composition.
The invention further relates to methods of stabilizing these multiple emulsion systems described above.
More specifically, the invention comprises a water-in-oil-in-water (W
1
-O-W
2
) multiple emulsion wherein the water-in-oil (W
1
/O) emulsion itself comprises an internal aqueous phase (W
1
) which contains a solute and optional surfactant; an oil phase O (an oil combined with a low HLB emulsifier, e.g., emulsifier with HLB less than 10) surrounding the internal aqueous phase; and a topically active compound which may be in either the aqueous W
1
or in O. The W
1
O phase is surrounded by an external aqueous isotropic phase (W
2
) containing cleansing surfactant, optional topically active compound (which may be the same or different as the first optional topically active compound), and optional solute. (It should be understood that some solute will almost always be present in the surfactant or will be formed when adjusting pH). One criticality of the invention is that surfactant phase W
2
must not contain an anionic surfactant with an amido group.
A second criticality is that the oil in the O phase (1) should not be comprised of more than 50% unsaturated compounds; or (2) should not be a volatile silicone (e.g., a silicone having viscosity of 10 centistokes or less).
As noted above, the invention can be distinguished from prior art U.S. Pat. No. 5,656,280 for example in that that patent requires the aqueous phase W
2
(e.g., external aqueous phase) to comprise a surfactant system capable of forming stabilizing liquid crystals. By contrast, the present invention requires that the external aqueous phase be an isotropic phase. The isotropic phase in turn is formed by selection of a specific surfactant system which must not contain an anionic surfactant with an amido group.
By definition, lamellar phase is a liquid crystalline phase whereas an isotropic phase is micellar; optically a lamellar phase would show birefringence under a polarized light source while a micellar phase does not exhibit this feature.
In particular, the invention comprises a W
1
-O-W
2
multiple emulsion composition comprising:
(1) about 1% to 99% by wt. of the composition, preferably 2% to 90% by wt., more preferably 5% to 80% of a W
1
/O emulsion comprising;
(a) about 1% to 99% of said emulsion of an internal aqueous phase comprising (i) water; (ii) 0.01 to 30% solute; and (iii) 0 to 30% surfactant;
(b) about 0.1% to about 99%, preferably 0.5 to 95%, more preferably 1 to 80% of the emulsion of an oil phase surrounding said internal aqueous phase comprising a non-volatile silicone compound, a volatile hydrocarbon compound, a non-volatile hydrocarbon compound or a mixture thereof;
(c) about 0.1 to 20%, preferably 1 to 15%, more preferably 1.5 to 15% of a low HLB emulsifier (e.g., having HLB under 10); and
(d) a topically effective amount (e.g., 0.01 to 40%, preferably 0.05 to 15% by wt.) of a first topically active compound which may be found in either aqueous phase (a) and/or oil phase (b); and
(2) about 1 to 99% by wt., preferably 20 to 95% by wt. of an external isotropic aqueous phase W
2
comprising non-amido anionic and/or other surfactants. Preferably the composition contains anionic and amphoteric surfactants, wherein the ratio of first surfactant (preferably anionic) to amphoteric is 100:1 to 1:100. The composition optionally contains a second topically effective compound, typically 0-40% by wt. of the external phase to perform a function identical to, similar to or different from the first topically active compound, and solute. The surfactant typically will comprise 2-80% of the aqueous phase.
The W
1
-O-W
2
multiple emulsion compositions are stable (e.g., typically they will not break down into a simple emulsion at room temperature for at least two weeks) and they exhibit exceptional esthetic and functional properties. The W
1
-O-W
2
multiple emulsion compositions are liquids or creams, and are capable of effectively delivering one or more topically active compounds to the skin or hair from a single composition.
REFERENCES:
patent: 4254105 (1981-03-01), Fukuda
patent: 5306498 (1994-04-01), Vesperini et al.
patent: 5332595 (1994-07-01), Gaonkar
patent: 5567426 (1996-10-01), Nadaud et al.
patent: 5589177 (1996-12-01), Herb et al.
patent: 5656263 (1997-08-01), Fructus
patent: 5656280 (1997-08-01), Herb et al.
patent: 5948855 (1999-09-01), Lin et al.
patent: 6103267 (2000-08-01), Mitchnick et al.
patent: 0717978 (1996-06-01), None
patent: 0715842 (1996-06-
Naser Mark Stephen
Vasudevan Tirucherai
Koatz Ronald A.
Page Thurman K.
Seidleck Brian K.
Unilever Home & Personal Care USA , division of Conopco, Inc.
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