(1) Calcium stearate:
White powder,melting point of 148-155 degrees, non-toxic, excellent internal lubricity and processability, no sulphide pollution, the dosage is generally 0.1-0.4PHR.
White or yellowish powder or particle, used as high tempreturer internal and external lubricants,although containing a small amount of polar groups, is still incompatible with PVC, but its lubrication efficiency is higher. It can improve the lubrication between polymer and metal, increase the extrusion efficiency, improve the dispersibility of colorants, and give the products good transparency and luster. The dosage was 0.1-0.5 PHR.
(3) Stearic acid
White particles, melting point 70-71 C. acts as external lubricant in high tempreture, internla lubricant in low tempreture,he dosage is generally 0.2-0.5 PHR. It has the effect of preventing chromatographic scaling, but the dosage is too large and easy to spray frost.
Powder, melting point 85-87 C, as internal lubricants,with excellent heat resistance and fluidity, can increase the amount of filler, and can promote plasticization. The thermal stability of PVC-U can be improved by mixing with wax. The general dosage is 0.2-0.6 PHR.
(5) Paraffin wax
Melting point 57-63 C, without polar groups, is a typical external lubricant. Because of its low melting point, easy evaporation and low melt viscosity, it can only lubricate in a narrow range. It is suitable for single-screw and twin-screw extruders. The general dosage is 0.1-0.8PHR. This product has poor transparency and easy to whiten.
(6) Polyethylene wax
White powder, softening point is about 100-117 C, because of its relatively large molecular weight, high melting point and low volatility, it also shows obvious external lubrication effect at higher temperature and shear rate. It is suitable for hard PVC single screw and twin screw extrusion with the usual dosage of 0.1-0.5PHR.