Surfactant is a substance with a very special chemical structure. It is widely used in the cosmetics industry. It is an auxiliary raw material in cosmetic raw materials. Although it is not used in much, it plays a big role. It is used in facial cleansers, moisturizing lotions, It is used in most products such as skin cream, shampoo, conditioner, toothpaste, etc. Its functions in cosmetics are diverse, and its main functions are: emulsification, washing, foaming, solubilization, sterilization, antistatic, dispersion, etc. Here we introduce its four main functions in detail.

(1) Emulsification

What is emulsification? As we all know, the most commonly used cream and lotion skin care products contain both oily ingredients and a large amount of water. They are a mixture of oily ingredients and water. But why can we not see it with the naked eye? Even if you can see the oil droplets inside, you can't see the water seeping out? This is because they have formed a very evenly mixed dispersion system, that is, the oily ingredients are evenly dispersed in the water in the form of tiny droplets, or the water is evenly dispersed in the oily ingredients in the form of tiny droplets. The former is what we call Oil-in-water, the latter is called water-in-oil, this type of cosmetics is called emulsion cosmetics, which is the most common type of cosmetics. However, under normal circumstances, oil and water are immiscible with each other. After the stirring stops, the oil and water return to a stratified state and cannot achieve a stable and uniform dispersion system. However, the oily ingredients in emulsion products such as creams and lotions The reason why it can form a uniformly mixed dispersion system with water is because surfactants are added to it. The special structure of surfactants can make oil and water, which are immiscible with each other, evenly mixed together and form a A relatively stable dispersion system is an emulsion. The role played by surfactants in emulsions is called emulsification. We call surfactants that play an emulsification role emulsifiers. Therefore, surfactants are present in the creams and lotions we use daily.

(2) Washing and foaming effects

Some surfactants have good washing and foaming effects. The soaps that everyone is very familiar with are a very commonly used type of surfactants. The soaps and soaps we use use the soap ingredients (surfactants) in them to achieve cleaning. , Foaming effect, some facial cleansers also use the soap ingredients in them to cleanse, but soap ingredients have strong cleaning power, can easily cause skin degreasing, and are slightly more irritating, so dry skin and sensitive skin It is not advisable to use this type of skin cleansing product. In addition, surfactants play a cleaning and foaming role in products such as bath soap, shampoo, hand soap, and toothpaste.

(3) Solubilization effect 

Surfactants can increase the solubility of some insoluble or poorly soluble substances in water, completely dissolving them in water, and finally forming a transparent state. This effect is called solubilization, and surface activity that plays a solubilizing effect is Agent is also called solubilizing agent. For example, we want to add an oily ingredient with good emollient properties to a transparent lotion, but the oil cannot dissolve in the water and can only float on the surface of the lotion in the form of small oil droplets. At this time, we can use the surface The solubilizing effect of the active agent allows the oily ingredients to be well dissolved in the lotion by adding surfactants, and the product finally presents a good transparent appearance. However, it should be noted that the amount of oily components dissolved through solubilization is limited, and it is difficult for larger amounts of oily components to be completely dissolved in water through solubilization. Therefore, as the amount of oily ingredients increases, the amount of surfactant also needs to increase to emulsify the oily ingredients and water. This is why some lotions are opaque and milky white. It is because there are more moisturizing oils in the surface. The active agent emulsifies it with water.

Surfactants can be divided into four categories according to their structural characteristics: anionic, cationic, zwitterionic and nonionic. Among them, anionic surfactants have better washing and foaming effects and are mostly used in cleaning products; cationic surfactants have better sterilizing, antistatic and hair-smoothing effects and are mostly used in conditioners; zwitterionic surfactants The active agent has a weak cleaning effect, but has good foaming, stabilizing and thickening effects. It is mostly used as an auxiliary anionic surfactant in cleaning products to enhance the cleaning effect of the product and reduce irritation; nonionic surfactants are used to It is good at emulsification and solubilization and has low irritation. It is mostly used in creams, lotions and aqueous products that require solubilization.