Lubricants are generally divided into internal lubricants, external lubricants and internal and external lubricants according to their specific role. External lubricant is mainly to reduce the polymer melt and screw, barrel and body bond strength between the lower friction between them; and internal lubricant is to reduce the friction between polymer molecules, increasing the polymer Processing fluidity and uniformity. The key to distinguish between internal and external lubricants is the compatibility of the lubricant with the polymer, the external lubricant compatibility is small.

However, the actual role of lubricants, unlike the definition of such a clear distinction, and under certain conditions, the role of internal and external lubrication will change, such as calcium stearate, its lubricating effect is more complex, there is no other formula lubricant Or internal lubrication ratio is relatively low, it only play the role of internal lubrication, lubricating oil ratio in the other cases, it will show the role of external lubrication. And, it works synergistically with many lubricants.