Composition comprising salt of acyl glutamate as primary surfactant or primary anionic surfactant and specific structurant polymers

#The invention relates to personal care compositions. The compositions are preferably aqueous-based, isotropic, personal care compositions. The compositions are preferably mild (defined for example by low percent zein dissolved relative to harsher compositions). Preferably, the compositions have good foam volume (a signal of cleansing to many consumers), have good structure (defined by initial bulk viscosity) and are stable (defined by viscosity and clarity maintenance and no phase separation). Preferably, the compositions are clear at a pH of 6.5 and lower, preferably of 6.0 and lower (generally the pH of the composition may be from about 3 to 6.5). Preferably the pH is from about 3.5 to 6.0, more preferably from about 3.5 to 5.5, more preferably 4.0 to 5.5. In particular, the invention relates to use of specific structuring polymers required to ensure that low pH, clear (isotropic) compositions have good structure and stability, as noted, and remain clear.

#Synthetic detergents, such as cationic, anionic, amphoteric, non-ionic surfactants, are widely used in personal care cleaning compositions. Anionic surfactants generally exhibit superior cleansing and foaming properties and are thus typically incorporated into such compositions. Anionic surfactants, however, also tend to be harsh on the skin.

#Since consumers desire milder compositions (i.e., compositions which are not as harsh and irritating on skin and skin proteins), it is known to replace some anionic surfactant with other surfactants (e.g., nonionic and/or amphoteric surfactants). Another approach is to associate anionic surfactants with amphoteric or cationic compounds to create surfactant complexes (see U.S. Pat. No. 4,443,362). Often these compositions suffer in foaming and/or cleansing performance.

#The invention relates to low pH cleansing compositions, preferably aqueous-based and clear, wherein salts of acyl glutamate are present as “primary surfactant” or, where the glutamate salts are “primary anionic surfactants” (although non-anionic may be present at greater than all anionic surfactants) and are simultaneously present in an amount equal to or greater than any other single surfactant present. When glutamate is not present in an amount equal to greater than any other single surfactant, such composition is not intended to be encompassed by compositions of the invention.

#More specifically, the compositions comprise specific structuring polymers which maintain clarity of the low pH isotropic compositions as well as structure (defined by initial bulk viscosity) and stability (defined by maintenance of viscosity and clarity when tested under defined conditions and maintenance of homogeneity and integrity without visible phase separation). Preferably (especially when using particular co-surfactants, e.g., betaine versus amphoacetate), minimum amounts of free fatty acids are used to ensure structure, clarity, and stability.

#Whether or not the glutamate is primary surfactant, or primary anionic surfactant while simultaneously present in amounts equal to or greater than any other single surfactant, it is seen that glutamate necessarily comprises 50% or greater of all anionic surfactant present and, as noted, is present in an amount equal to or greater than, preferably greater than, any other single surfactant in the composition. Because of the properties of glutamate noted above, it would not have been previously contemplated to form low pH compositions where glutamate is primary surfactant or primary anionic surfactant while maintaining structured, stable, single phase, clear (isotropic) formulations. In some preferred compositions, the amount of short chain glutamate (C10 or below) is minimized (to enhance foaming). Particular structurants are used to enhance stability and structuring (while maintaining clarity), even at very low pH.