Since hair is always exposed to physical stimulation by daily hair care routines such as heat drying with a hair dryer and brushing, and chemical stimulation by shampooing, permanent weaving, dyeing and bleaching, it is often in a damaged state with a partial component or structural loss. A change in hair quality due to aging accelerates this damage and also causes the loss of resilience and strength to hair.
It is a common practice to protect or repair hair in a damaged state by making up for the lost component or structure or analogue thereof. Interaction (affinity) between a protecting base and hair is considered important for the exhibition of a protecting or restoring function, and a method of using a sphingolipid or protein derivative as a protecting base has been used widely as a useful technique. For example, a hair shampoo agent containing a surfactant made of an anionic surfactant and a bipolar ionic surfactant, cationic polymer, and ceramide or glycosylceramide has been proposed (Japanese Patent Application Laid-Open No. Hei 8-59443). The agent however cannot contain an adequate amount of a protecting base such as a ceramide or glycosylceramide because it has a high melting point and easily crystallizes. Moreover, even this protecting base added in a slight amount does not readily penetrate into the hair. There is a continuing desire to improve the amount of protecting base penetrating into the hair. The conventional hair cosmetic composition is therefore accompanied with the problem that the protecting base incorporated therein cannot function well.