Surfactant is a very special chemical substance. It is widely used in cosmetics industry. It is an auxiliary material for cosmetic materials. Although it is not used in a large quantity, it plays a great role in the application of most products such as cleansing cream, moisturizing lotion, skin cream, shampoo, conditioner, toothpaste and so on. Its functions in cosmetics are various, including emulsification, washing, foaming, solubilization, sterilization, antistatic and dispersion. Here we will introduce in detail its four main functions.
What is emulsification? As everyone knows, what we usually use in cream and lotion is oily and contains a lot of water. They are mixtures of two substances, oily ingredients and water. But why do we not see the oil droplets inside the naked eye and do not see the moisture coming out of it? This is because they have formed a very uniform mixing dispersion system, that is, oily ingredients are evenly dispersed in water in the form of tiny droplets, or water is evenly dispersed in oily components in the form of tiny droplets. The former is called oil in water, and the latter is called water in oil. This type of cosmetics is called emulsion cosmetics, which is common in cosmetics One type. However, under normal circumstances, oil and water are not mutually soluble, and after mixing stops, the oil and water return to a stratified state and can not reach a stable and uniform dispersion system. However, the oiliness components in the emulsion products such as cream, emulsion and water can form a homogeneous dispersion system because of the addition of surfactants and the special structure of surfactants. The immiscible oil and water are evenly mixed together to form a relatively stable dispersion system, i.e. emulsion. The role of surfactant in the emulsion is called emulsification, and the surfactant that plays the role of emulsification is called emulsifier. Therefore, there are surfactants in the cream and emulsion used in our daily life.
(2) Washing and foaming
Some surfactants have good washing and foaming effects. The soap that we are very familiar with is a kind of common surfactant. The soap and soap we use use are the soap components (surfactant) to achieve the cleaning and foaming effect. Some facial cleansers also play a cleaning role through the soap components inside, but the soap components have strong cleaning power , easy to cause skin degreasing, and irritation is also slightly strong, so dry skin and sensitive skin should not use this kind of skin cleaning products. In addition, surfactants play a cleaning and foaming role in bath, shampoo, hand sanitizer and toothpaste.
Surfactants can increase the solubility of some insoluble or insoluble substances in water, so that they are completely dissolved in water, and finally form transparent state. This effect is called solubilization, and the surfactant that plays the role of solubilization is also known as solubilizer. For example, we want to add a kind of oily ingredients with good moisturizing properties in transparent makeup water, but the oil can not be dissolved in water, and can only float on the surface of cosmetic water in the form of small oil drops. At this time, we can make use of the solubilization effect of surfactants to make the oily ingredients dissolve well in the makeup water, and the product finally presents a good transparent appearance. However, it should be noted that the amount of oil-based components dissolved by solubilization is limited, and a large number of oil-based components are difficult to be completely dissolved in water by solubilization. Therefore, with the increase of oily ingredients, the amount of surfactant also needs to be increased. The oil-based components and water are emulsified, which is why some make-up water is opaque and milky white, because there are many oil components in the skin moistening, and surfactants emulsify them with water.
Surfactants can be divided into anionic, cationic, zwitterionic and nonionic surfactants according to their structural characteristics. Among them, anionic surfactants have good washing and foaming effects, which are mostly used in cleaning products; cationic surfactants have good bactericidal, antistatic and hair softening effects, which are mostly used in hair conditioner; zwitterionic surfactants have weak washing effect, but have good foaming, foam stabilizing and thickening effects, which are mostly used to assist anionic surface activity in cleaning products It can enhance the cleaning effect of products and reduce irritation. Nonionic surfactants are good at emulsification and solubilization, and are less irritating. They are mainly used in cream, emulsion products and water products that need solubilization.