Hair care, esterquats

The single largest market for quaternary ammonium compounds is as fabric softeners. In 1993 this market accounted for over 50,000 metric tons of quaternaries in the United States (235). Consumption of these products is increasing at an annual rate of about 2—3%. The hair care market consumed over 9000 metric tons of quaternary ammonium compounds in 1992 (236). The annual consumption for organoclays is estimated at 12,700 metric tons (237). Esterquats have begun to gain market share in Western Europe and growth is expected to continue. 

During the last decade, the dialkyl esterquats have to a large extent replaced the stable dialkyl quats as rinse cycle softener, which is the single largest application for quaternary ammonium compounds. The switch from stable dialkyl quats to dialkyl esterquats represents one of the most dramatic changes of product type in the history of surfactants and it is entirely environment driven. Unlike stable quats, esterquats show excellent values for biodegradability and aquatic toxicity. Esterquats have also fully or partially replaced traditional quats in other applications of cationics, such as hair care products and various industrial formulations. Normal esterquats are covered in a special chapter of this book and are not discussed further here. 

Several esterquats have been developed commercially for hair care applications [108-110]. These products are derived from alkanolamines, mainly triethanolamine, methyldiethanolamine, or dimethylamino-l,2-propanediol [111], and preferably fatty adds of vegetable origin like oleic and palmitic sources. Some examples are given in Fig. 15. 

A number of patent publications disclose alkanolamine-derived esterquats for use in cosmetic hair care and skin care preparations. Several trietha-... 

Triethanolamine based esterquats are a mixture of mono- di- and tries-terquats. It is claimed that for softeners and hair conditioners an esterquat with at least 50% diester content is preferred [49]. Methyldiethanolamine-based esterquats are mainly diesterquats with only slight amounts of mono-esterquat. Monoesterquats are useful as cationic surfactants in hair care formulations [124]. Solid esterquats with improved dispersibility and emulsifying properties are obtained by quaternization of fatty acid triethanolamine esters in the presence of a dispersing agent or nonionic emulsifier [125-127]. Esterquats can be used in sprayable conditioning systems for hair care [128]. 

Other complex reaction mixtures of esterquats based on triethanolamine with fatty adds and hydroxycarboxylic acids or dicarboxylic acids or polyols and dicarboxylic acids have been suggested for use in hair and body care [18,19,24,142]. Sorbitan esterquats are claimed for personal eare applications like skin and hair cleansing [143]. 

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