The amphoteric surfactant is a surfactant that contains both anionic and cationic hydrophilic groups in the same molecule. Its biggest feature is that it can both give protons and accept protons. In the process of use, it has the following characteristics: excellent softness, smoothness and antistatic properties to the fabric; certain sterilization and mildew resistance; good emulsification and dispersion.
The amphoteric surfactant molecule is different from a single anionic or cationic type. There are both acidic and basic groups at one end of the molecule. Acidic groups are mostly carboxyl, sulfonic or phosphoric acid groups, while basic groups are amine or quaternary ammonium groups, which can be mixed with the anionic and nonionic surfactant, and are resistant to acids, alkalis, salts and alkaline earth metal salts.
The commonly used synthetic amphoteric surfactants now have mostly carboxylic acid groups and a few sulfonic acid groups. The cationic part is mostly amine salt or quaternary amine salt. The cationic part composed of amine salt is called amino acid type; the cationic part composed of quaternary amine salt is called betaine type.
Amphoteric surfactant usually has good washing, dispersing, emulsifying, sterilizing, softening fibers and antistatic properties. They can be used as textile finishing auxiliaries, dyeing auxiliaries, calcium soap dispersants, dry cleaning surfactants and metal corrosion inhibitors. However, this type of surfactant is more expensive, and the actual application range is smaller than other types of surfactants.