External lubricant: this lubricant has poor compatibility with molding resin, so it is often used in molding machinery or molds. It forms a lubricating layer with resin to facilitate resin flow and product demoulding, such as paraffin.

Internal lubricant: this kind of lubricant has good compatibility with resin, and is often mixed into resin to reduce the melt viscosity of resin and improve its fluidity. Such as butyl stearate, lead stearate, etc. Stearates are not only good lubricants, but also effective stabilizers.

It is worth noting that lubricants have been added to many composite heat stabilizers. In the production of PVC products, the compound heat stabilizer should be used reasonably according to the product description and reference formula. If there is no special process requirement, no additional lubricant is generally added to avoid "over-lubrication" and other adverse conditions.