Plastic lubricant is a kind of additive used to improve the processability and apparent properties of plastics, rubber and other polymers. In addition to reducing friction in a general sense and improving the fluidity and demoulding property of resin or rubber during processing, the function of plastic lubricant can also be extended to increase the surface smoothness of products, prevent adhesion between products and other interface properties.

Plastic lubricants can be divided into internal and external plastic lubricants. The internal and external plastic lubricants are mainly distinguished according to their compatibility with resins. The affinity between inner plastic lubricant and resin is large, and its role is to reduce the force between macromolecules. The affinity between external plastic lubricant and resin is small, and its role is to reduce the friction between resin and processing machinery. The distinction between internal and external plastic lubricants is relative, without strict criteria. In resins with different polarity, the role of internal and external plastic lubricants may change.