Lubricants are used in plastic processing to enhance the demolding properties of products and prevent defects caused by adhesion within the machine or mold. Usually added to the molding compound or coated on the surface of the mold cavity. Common lubricants include fatty acids and their salts, as well as long-chain fatty hydrocarbons. According to the different mechanisms of lubricant action, it can be divided into external lubricants and internal lubricants. (1) External lubricant: This lubricant has poor compatibility with molding resins, so it is commonly used in molding processing machinery or molds. It forms a lubricating layer between the lubricant and the resin, which facilitates resin flow and product demolding, such as paraffin. (2) Internal lubricant: This type of lubricant has good compatibility with resin and is often mixed into the resin to reduce its melt viscosity and improve its flowability. Such as butyl stearate, lead stearate, etc. Stearates are both good lubricants and effective stabilizers.