PVC Lubricant is an indispensable additive in PVC processing. Adding appropriate amount of lubricant in PVC can reduce the friction between particles and macromolecules in PVC melt before PVC melting; Reduce friction between PVC melt and plastic mechanical contact surface. Appropriate amount of lubricant can improve the fluidity of PVC melt, improve production efficiency, prevent the degradation of PVC caused by friction heat, and improve the appearance quality of products.
According to the function can be divided into external lubricants and internal lubricants. The external lubricant has poor compatibility with PVC and is easy to migrate from the resin melt inside to the surface, forming the lubricant interface layer, thus reducing the friction between particles and mechanical contact surface between PVC melt and plastic before PVC melting. Internal lubricant contains polar groups, and has good compatibility with PVC, can reduce PVC intermolecular force, reduce melt viscosity, improve melt fluidity.
The division of internal and external lubricants is only relative, and there is no strict classification standard. In resins with different polarities, the role of internal and external lubricants may change. For example, alcohol stearate, amine stearate, butyl stearate, and monotriglyceride stearate provide internal lubrication for polar resins (such as PVC and PA), but show external lubrication for non-polar resins (such as PE and PP).
On the contrary, macromolecule paraffin and other polar resin compatibility is poor, such as in polar PVC used as external lubricant, and in PE, PP and other non-polar resin is internal lubricant. At different processing temperatures, the role of internal and external lubricants will change, such as stearic acid and stearic alcohol used in PVC calendering molding early, due to low processing temperature, poor compatibility with PVC, mainly plays an external lubrication role, when the temperature rises, and PVC compatibility increases, is transformed into internal lubricant role.