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Shampoo

Hair shampoos are a common household commodity in many communities around the world. Human hair becomes soiled from exposure to environmental factors as well as from the sebum secreted by the scalp. The build-up of the sebum causes the hair to have a dirty and/or greasy feel and an unattractive appearance. It is the function of shampoo products to cleanse the hair and scalp by removing the excess dirt and sebum. Shampoos may be variously formulated as liquids, creams, pastes, aerosols or dry formulations. The majority are liquids, either clear or pearlised. The principal constituents of most liquid shampoos can be classified as detergents, thickeners, foam stabilisers and boosters, perfumes, preservatives, diluents or bulking agents, conditioning agents or emollients, pearlisers/opacifiers and colours. The bulking agents are included primarily for commercial purposes, so as to allow a consumer to dispense a typical amount of shampoo so as to achieve a desirable level of lather and cleaning. The properties of a good shampoo often depend upon the intended application, but may include the ability to cleanse the hair and scalp of the user thoroughly, but without stinging, irritation or the removal of excess natural oils from the scalp, cosmetic and aesthetic characteristics including the imparting of lustre, softness and manageability and the formation of foam necessary for removal of dirt particles. Consumers consider foaming ability an important aesthetic consideration in assessing the acceptability of a shampoo. Conditioning shampoos comprising various combinations of detersive surfactant and hair conditioning agents are known. These shampoo products typically comprise an anionic detersive surfactant in combination with a conditioning agent such as silicone, hydrocarbon oil, fatty esters, or combinations thereof. These shampoos have become more popular among consumers as a means of conveniently obtaining hair conditioning and hair cleansing performance all from a single hair care product. Shampoos in liquid form usually contain a large proportion of water. Water is frequently used as the bulking agent in liquid shampoos, because of its inert properties, its miscibility with other shampoo constituents, its low cost, and its ease of removal from hair during the normal washing process. Dandruff, seborrheic dermatitis and psoriasis are symptomatic disorders that show a predilection for the scalp. These particular scalp conditions are of unknown causes and are generally characterized by varying degrees of redness, scaling and oftentimes itching. It is widely believed that dandruff is associated with excess secretions of the sebaceous glands which become abnormally accelerated by bacterial infection of the scalp. For this reason, hair treatment compositions containing various bactericides have previously been used in the prior art for preventing dandruff. Antidandruff shampoos are well known in the art and rely upon various actives for their antidandruff effectiveness. Such compositions are not only designed to relieve the dandruff condition, but also to effectively clean the hair. Anti-dandruff shampoos typically incorporate an anti-dandruff active and detersive surfactants. Among the preferred type of anti-dandruff agents are particulate, crystalline anti-dandruff agents, such as sulfur, selenium disulfide and heavy metal salts of pyridinethione.

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