PVC Lubricant Is Non-toxic And Has Excellent Lubricity And Processability

The main properties of commonly used PVC lubricants are as follows:

(1) Calcium stearate:

White powder, melting point 148-155 ℃, non-toxic, excellent lubricity and processability, no sulfide pollution, combined with basic lead salt and lead soap, can improve the gelation speed, the dosage is generally 0.1-0.4PHR.

(2) Oxidized polyethylene wax

White or light yellow powder or granules, although oxidized polyethylene wax contains a small amount of polar groups, it is still incompatible with PVC, but its lubricating efficiency is high, which can improve the lubricity between polymer and metal, improve extrusion efficiency, improve The dispersibility of the colorant gives the product good transparency and gloss. The dosage is 0.1-0.5PHR.

(3) Stearic acid

White or slightly yellow particles, melting point 70-71 ℃. Slow volatilization at 90-100 ℃, used as external lubricant in hard PVC processing, the dosage is generally 0.2-0.5PHR, and has the effect of preventing chromatographic fouling, but the amount is too large and easy to spray.

(4) Glyceryl Stearate

Powder, melting point 85-87℃, excellent heat resistance and fluidity, can increase the amount of filler and promote plasticization. Used together with waxes, it can improve the thermal stability of PVC-U. The general dosage is 0.2-0.6PHR.

In practice, it has been found that when two or more lubricants are used together, different effects than when used alone. In the formulation of profiled materials, most of them use compounding methods.

(5) Paraffin

Melting point 57-63 ℃, no polar groups, is a typical external lubricant. Due to its low melting point, easy evaporation and low melt viscosity, it can only play a lubricating role in a narrow range, and is suitable for extrusion by single and twin screw extruders. The general dosage is 0.1-0.8PHR. This product has poor transparency and is easy to whiten.

(6) Polyethylene wax

White powder with a softening point of about 100-117°C. Due to its large relative molecular mass, high melting point and low volatility, it also shows obvious lubricating effect at higher temperature and shear rate. It is suitable for single and twin screw extrusion of rigid PVC, and the usual dosage is 0.1-0.5PHR.