With the continuous deepening of the development and application research of surfactants, its application range is also expanding. At present, surfactants have become the main components of detergents, and they also have many important applications in cosmetics, such as emulsifying, dispersing, solubilizing, foaming and cleaning in cosmetics.

1) Emulsification

The phenomenon of uniformly emulsifying non-water-soluble substances in water to form an emulsion is called emulsification. Emulsifiers are mainly used in the production of creams and lotions in cosmetics. The common powdery cream and neutral cream are both 0/W type emulsions, which can be emulsified with anionic emulsifier fatty acid soap (soap). It is easier to prepare emulsions with less oil by soap emulsification, and the gelling effect of soap can be Make it have a greater viscosity. For cold creams containing a lot of oil, the emulsions are mostly w/O type, and natural lanolin with large water absorption and high viscosity can be used for emulsification. At present, the most widely used non-ionic emulsifier is that the non-ionic emulsifier is safe and has low irritation. The famous sorbitan fatty acid ester (Span) and its ethylene oxide adduct (Tween) are good composite non-ionic emulsifiers. Span is lipophilic and Tween is hydrophilic, and the two are mixed. Used in O/W emulsions, it can form emulsions with good stability and high skin affinity.

2) Solubilization

The phenomenon of increasing the solubility of slightly soluble or insoluble substances is called solubilization. When the surfactant is added to water, the surface tension of the water will drop sharply at first, and then the micelles of surfactant molecules are formed. The concentration of surfactant used to form micelles is called the critical micelle concentration. When the concentration of the surfactant reaches the critical micelle concentration, the micelle can absorb the oil or solid particles at one end of the lipophilic base, thus increasing the solubility of the slightly soluble or insoluble matter.

Solubilizers in cosmetics are mainly used in the production of lotions, hair tonic, and hair tonic. Surfactants used as solubilizers should have high hydrophilicity, HLB>15, such as polyoxyethylene hardened castor oil, polyoxyethylene castor oil, fatty alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene-polyoxypropylene Ether, polyoxyethylene sorbitan fatty acid ester and polyglycerin fatty acid ester, etc.

Oily ingredients in cosmetics, such as fragrances, oils, and oil-soluble vitamins, have different solubilization formations due to differences in structure and polarity. Therefore, suitable surfactants must be selected as solubilizers. For example, the solubilization objects of the lotion are perfumes, oils and pharmaceuticals, etc., so alkyl polyoxyethylene ethers can be used for solubilization. Although alkylphenol polyoxyethylene ethers (OP type, TX type) have strong solubilizing ability, they are irritating to the eyes and are generally not used. In addition, castor oil-based amphoteric derivatives have excellent solubility in perfume oils and vegetable oils, and such surfactants are non-irritating to the eyes and are suitable for the preparation of non-irritating shampoos and other cosmetics.

3) Dispersion

The phenomenon in which water-insoluble substances form particles in a uniformly dispersed state in water is called dispersion. The dispersion system of cosmetics includes three parts: powder, solvent and dispersant. Powder can be divided into two types: inorganic pigments (such as talc, mica, titanium dioxide, carbon black, etc.) and organic pigments (such as phthalocyanine blue, etc.), mainly to make cosmetics have a good color tone, can cover the background color, and have good use Solvents are divided into two types: water-based and non-aqueous. Dispersants used as media are hydrophilic (applicable to water systems) and lipophilic (applicable to non-aqueous systems). Therefore, the system has multiple combinations.

Many surfactants used in dispersants are both emulsifiers and dispersants, such as fatty alcohol polyoxyethylene ethers, sorbitan fatty acid esters, fatty alcohol polyoxyethylene ether phosphates, alkyl ether carboxylates and alkyl ethers. Sulfonates, etc., they all have good dispersing properties. In order for the powder to be fully dispersed in the liquid, the liquid must be able to wet the surface of the powder well. Therefore, when choosing a surfactant, first consider the HLB of the powder surface and the dispersion medium. Generally, when using lipophilic powders in water-based systems, hydrophilic surfactants should be used mainly.

4) Cleaning effect

Personal products used for cleaning mainly include shampoo, shower gel and facial cleanser. In addition to cleaning, foaming and moisturizing functions, the main consideration at present is mildness to the skin. This requires that the surfactant does not damage the epidermal cells, does not affect the skin protein, and does not penetrate or penetrate the skin. To keep the skin oil and the skin itself in a normal state.

Anionic surfactants have a long history of cleaning. The detergency of soap is unmatched by other detergents. Sodium lauryl sulfate is a commonly used raw material in cleansing cosmetics, it can make the skin achieve a good cleaning effect. Amphoteric surfactants, imidazoline, cocamidopropyl betaine and amino acids are all mild cleansing surfactants, and are indispensable components for the preparation of high-end facial cleansing products, hair care shampoos and baby shampoos.

5) Soft and antistatic effect

Cationic surfactants are the main conditioners in hair conditioning products such as conditioners and conditioners. They have good softness and antistatic ability and play a unique role in hair softening conditioners. The most commonly used cationic surfactants are monoalkyl and dialkyl quaternary ammonium salts, namely C16-18 monoalkyl ammonium salts, double C16-18 alkyl quaternary ammonium salts and alkylbenzyl quaternary ammonium salts. Asymmetric tallow, octyl dimethyl quaternary ammonium salt and 3-cetyl methyl ammonium salt, these quaternary ammonium salts have good effects on dry combing, wet combing and detackification of hair. Recently, the most eye-catching is the quaternary ammonium salt derived from lanolin fatty acid. It is less irritating and has the water retention and wetting properties of lanolin and the characteristics of cationic surfactants, which can give hair moist and unique touch such as softness.

6) Wetting and penetration

As cosmetics, they must not only have beauty effects, but also feel comfortable and soft when used. These are inseparable from the wetting effect of surfactants. In this regard, biosurfactants have achieved remarkable results. As an important component of biological cells, phospholipids play an important role in cell metabolism and cell membrane permeation regulation, and have good moisture retention and permeability to human skin. Sophorolipid biosurfactants have a peculiar affinity for the skin, which can make the skin soft and moisturized. Using biochemical synthesis and other methods to prepare corresponding biochemical active substances and vitamin derivatives, enzyme preparations, cell growth factors (EGF, DFGF), collagen, elastin, ceramide and hyaluronic acid, etc., these substances can be used in cosmetics. Penetrates into the skin, participates in the metabolism of skin cells and tissues, changes the structure of skin tissues, etc., so as to achieve the effects of anti-wrinkle, anti-aging and whitening.