A release agent is an interfacial coating applied between two surfaces that tend to stick together, enabling easy separation while leaving surfaces smooth and clean. Release agents are used in molding operations involving fiberglass-reinforced plastics, metal die casting, polyurethane foams and elastomers, injection-molded thermoplastics, vacuum-formed foam sheets and extrudedprofiles. During molding, other plastic additives, such as plasticizers, may migrate to the interface, requiring asurface release agent to remove them. In theory, a release agent should have high tensile strength so that repeated contact with molding resindoes not readily wear it away, especially when the resin contains abrasive mineral fillers or glass-fiber reinforcement. The release agent should resist chemicals so thatcontact with the chemical constituents of different resins, particularly styrene and amines, does not dissolve it. It should also resist heat and stress, without readilydecomposing or wearing away. It should adhere to the mold rather than transfer to the workpiece, so that painting and other secondary operations are not hindered.。

Choosing a Release Agent: Common release agents fall into three categories: inorganic, organic and polymeric.

　　Inorganic release agents include compounds based on talc, mica, kaolin and white clay, mainly used during rubber processingas separating agents to prevent rubber sheets and semi-finished products from sticking.

　　Organic release agents include fatty-acid soaps (potassium, sodium, ammonium and zinc soaps), fatty acids, paraffin, glycerol and petroleum jelly.

　　The third category is polymeric release agents, including silicone oils, polyethylene glycol and low-molecular-weight polyethylene. Their release efficiency and thermal stability aremuch better than those of organic release agents.