How to use PE wax to solve the problem of "poor processing fluidity" in PVC processing:
Specific manifestations: high melt viscosity and excessive equipment torque; Or "shark skin", the surface of the product ripples and lacks materials; Or slow extrusion speed.
Main reasons: PVC molecular chains have strong rigidity and high melt elasticity; Uneven dispersion of fillers such as calcium carbonate or additives increases melt resistance.
Working principle: The molecular chain of PE wax is short and has a certain compatibility with PVC. It can penetrate between PVC molecular chains, weaken intermolecular forces, provide internal lubrication, and reduce melt viscosity; At the same time, some PE wax migrates to the surface of the melt, forming a lubricating film that reduces friction between the melt and the screw or barrel, providing external lubrication. The dual effect improves liquidity.
Applicable scenario: In the extrusion production process of hard products such as PVC or UPVC pipes, the high filling amount of calcium carbonate (20% -40%) leads to high melt viscosity and excessive extrusion torque.
Specific operation: Add polyethylene wax with a viscosity of 30-200 CPS or oxidized polyethylene wax with good compatibility with the formula, with an addition amount of 0.5% -1.5% (hard products) or 1% -2% (soft products).
Effect: Improve melt flow rate (MFR) by 10% -30%, reduce equipment torque by 8% -15%, increase extrusion speed by 5% -10%, and avoid defects such as "material shortage" and "ripples".
Attention: Avoid using PE wax with high viscosity (such as 600cps), as it will increase the viscosity of the melt and instead reduce its flowability.