1. Field of the Invention
This invention relates to a liquid shampoo composition, and particularly to such composition in which the specific odor of a skin sensation inducing aromatic chemical contained in the composition is effectively depressed while a sufficient pharmaceutical effect on use being assured, and which has good stability at low temperatures.
2. Description of the Prior Art
In the hair care industry, it has been a conventional practice that about 1% of a skin sensation inducing aromatic chemical, such as menthol, is incorporated into a shampoo composition expecting its pharmaceutical effect obtainable during or after the hair wash.
These shampoos, generally called "tonic shampoos" or the like, have been used mainly by male consumers. The tonic shampoos such as those containing menthol as the skin sensation inducing aromatic chemical can give sufficient refreshing feel, but because of their intense specific odor ascribed to the skin sensation inducing aromatic chemical, they have not been cared for by some consumers and especially by female consumers, and thus have had a quite limited market. Further, the specific or inherent odor of the aromatic chemical has made it difficult to impart a variety of fragrances to the shampoo compositions by ordinary mixed purfumes.
When the incorporation amount of the skin sensation inducing aromatic chemical such as menthol is reduced, the specific odor thereof can be mitigated but with only insufficient pharmaceutical effect. In order to obtain a certain pharmaceutical effect by a small incorporation of the chemical, a so-called percutaneous absorption accelerator could be used. However, among safe and economic materials, no adequate accelerator is known for enhancing the percutaneous absorption during only a temporary contact when the hair is shampooed. In turn, another approach has been made on odorless or less odoriferous external agents such as skin sensation inducing chemicals, but those giving sufficient effect and also safe to the human body have not yet been developed.