Benefit agent compositions comprising mixtures of alpha-hydroxy esters

#The present invention relates to personal wash cleanser compositions comprising an a-hydroxy benefit agent which in turn comprises mixtures of both short chain (C.sub.2 -C.sub.10) and long chain (C.sub.11 -C.sub.24) a-hydroxy acid esters. More specifically, by combining the longer term moisturizing effect of short chain esters, (note, short chain esters such as butyl (S)- or octyl (S)-lactate often have initial drying effect) with the shorter term moisturizing/masking benefit of long chain esters (e.g., octadecyl (S)-lactate), applicants have obtained superior compositions. Mixing both short and long term moisturizing effects allows compositions to be prepared which have long term beneficial effects while providing short term visual tactile effects of soft, smooth skin. More specifically, applicants have been able to mix short chain esters (normally drying) with long chain esters and significantly reduce the drying effect of the short chain esters while providing longer term moisturizing effects associated with the shorter chain esters.

#The use of short chain .alpha.-hydroxy acid esters (e.g., C.sub.1 to C.sub.4 alkyl lactates to treat acne) or long chain .alpha.-hydroxy acid esters (e.g., long chain lactate ester emollient) is broadly taught in the art. No art, however, teaches a specific combination of long and short chain esters of .alpha.-hydroxy acid (e.g., lactic acid) or that, in combination, the long and short chain esters could provide multiple benefits.

#U.S. Pat. No. 4,540,567 to Oneto et al. (assigned to Lever Brothers), for example, teaches compositions comprising short chain C.sub.1 -C.sub.4 alkyl lactate (primarily for treatment of acne) or mixtures which are dissolved in a mixture of water and water-miscible C.sub.2 -C.sub.4 alkylene glycol or a polymer thereof. Alkylene glycol is said to act as a vehicle to help limit dehydration of skin and improve sensory feel of product. There is no teaching or suggestion of combining with long chain a-hydroxy acid esters or that by doing so dehydration effect can be ameliorated.

#FIG. 1 shows that it is really only the long chain ester which is generally non-drying and that the short chain esters when used alone, have a drying effect. Nonetheless, it is desirable to incorporate short chain esters because they hydrolyze to lactic acid more quickly than long chain esters and deliver long term benefits associated with lactic acid (See Example 1).

#FIG. 2 shows that, quite unexpectedly, when combined with long chain ester, the moisturizing effect of long chain ester (octadecyl (S)-lactate) is not compromised. An advantage of the invention is the ability to retain moisturizing effect of long chain ester without sacrificing long term benefit of short chain ester.

#FIG. 3 again shows that, when combined with long chain ester (cetyl lactate), moisturizing effect of long chain ester is not compromised.

#The present invention relates to compositions intended to provide both long term and short term moisturizing benefits to the skin. Compositions may be compositions such as creams and cosmetic lotions for the skin, or they may be rinse-off compositions such as shower gels.

#More specifically, short chain length .alpha.-hydroxy acid esters provide long term moisturizing benefits as well as other benefits (e.g., antiacne) to the skin. However, the short chain .alpha.-hydroxy acid esters also cause skin drying in the short term. Thus, it would be greatly beneficial to deliver long term moisturizing benefit to the skin (i.e., through short chain esters of hydroxy acid) while at the same time masking or eliminating the short term dryness effect.

#Unexpectedly, applicants have found that the desired benefits can be obtained by providing compositions having a specific combination of long and short chain .alpha.-hydroxy acid esters.