The development of new surfactants with special structure and the pursuit of mildness is a time-consuming and endless task. Another way to improve the mildness of products is to make use of the compounding and coordination of surfactants or to improve the process and chemical structure of the original surfactants.

(1) Purification of surfactants many of the pure products of surfactants are tested to be of low irritation and high mildness. However, due to many reasons such as raw materials, process and side effects, some impurities will be brought into the products, such as unreacted raw materials, by-products, toxic colored substances, etc., which limit the use of these surfactants in cosmetics as high-quality and mild varieties Application in products and personal hygiene products. The most typical example is the monosodium sulfosuccinate variety, which is even ahead of imidazoline and betaine amphoteric surfactants in the order of mildness. However, it is ironic that its industrial products are quite irritating to the skin and are not suitable for use as mild surfactants. Another example is betaine type amphoteric surfactant, which is also ranked in the top of the list for its mildness, but it is irritating due to the presence of free amines and excessive sodium chloroacetate in industrial products. At present, a lot of work has been focused on the process optimization and product purification of the original excellent mild surfactant varieties, so as to return its mild nature. High purity irritant free imidazoline amphoteric surfactant prepared by Rhone-Poulenc, crystal betaine amphoteric surfactant prepared by our laboratory, AES prepared by ballestra by scraping film drying method for dioxane removal are all such varieties.

(2) Surfactant compounding
Several commonly used bulk surfactant products, such as Las, AES, SDS and so on, have serious irritant problems. In addition to improving their chemical structure and production process, they can also be compounded with some mild surfactants. By using the synergistic effect of surfactant compounding system in irritancy, the softness of the compounding system can be increased, and low-grade raw materials can be upgraded. In this aspect, many beneficial attempts have been made, such as reducing the irritancy of 3:1 mixture of sodium amidosulfosuccinate and AES to a lower level than that of amphoteric surfactants, which can be used to prepare children's shampoo and high-grade low irritant shampoo. In addition, when a small amount of APG (alkyl glucoside) is added to the LAS, AES / alkanolamide dishwashing detergent mixture system, the irritation of the formula can be reduced by one level, reaching the level of basically no stimulation. The combination of 25% alkyl polyglycosides and 75% AES can reduce the stimulation of AES by more than 70%. Of course, the compounding system also has limitations, especially for the current popular concentrated formula, in which a large number of surfactants are used, at this time, it is impossible to fundamentally solve the problem of mildness by compounding, only by using the main surfactant with moderate performance can fundamentally solve the problem. Therefore, the development of new mild surfactants and the use of existing surfactants are two aspects to improve the product's mild, complementary and indispensable.