tween is a type of nonionic surfactant, which is a hydrophilic emulsifier. as a emulsifier, it is full of diverse fatty acid, due to the hlb value is 9.6 to 16.7, it can be dispersed in water, alcohol and other organic solvents, as a result, tween is a quite useful emulsifier in many fields, such as food, cosmetic, textile, etc. the seriers including: tween-20, tween-40, tween-60, tween65, tween-80, tween-85.