Calcium carbonate filler masterbatch is one of the most common cost-reduction tools in polyolefin film and moulding.
Benefits
- Replaces part of the polymer at lower cost
- Increases stiffness and reduces blocking
- Improves printability and gives a paper-like feel
- Can raise output on some lines because filled melts cool faster
Limits
Too much filler reduces tear and impact strength, can cause die build-up and increases density, so the cost saving per square metre is smaller than per kilogram. Moisture in the filler causes voids and lacing.
Good practice
Use surface-treated, fine carbonate with a narrow size distribution, keep moisture low and increase dosage in steps while checking dart impact and tear. Talc gives stiffness in PP mouldings; barium sulphate raises density and gives a smooth surface.
