Calcium carbonate (CaCO3) filler masterbatch (or filler master batch) is a concentrated mixture of calcium carbonate and other additives encapsulated during a heat (mainly extrusion) process into a carrier polymer resin which is then cooled and cut into granules (pellets) making CaCO3 masterbatch a solid additive for plastics. Since common CaCO3 MB was originally intended for filling plastics to replace a part of expensive carrier resin it is often called filler masterbatch or filler additive.
Due to high filling ratio (concentration) of calcium carbonate in the polymer matrix it is also called calcium carbonate concentrate.
Today advanced calcium carbonate concentrates not only fill but also impart other properties to (improve) plastics. In this case they rather act as functional additives than simply common fillers, and may be referred to as additive masterbatches.
Calcium carbonate masterbatch alone is normally not used for coloring plastics and, thus, is different from white and color masterbatches. However when used together with white TiO2 based masterbatch it not only increases whiteness due to its natural color but also facilitates white pigment dispersion in the polymer matrix contributing to higher opacity.
Calcium carbonate concentrates usually contain from 60% to as high as 90% of CaCO3 in the polymer matrix and are commonly based on polyolefin (PE or PP) resins, though other polymers (PS, EPS, ABS etc.) can be filled as well.
Among main benefits of calcium carbonate concentrates are cost savings, productivity gains, better products quality and environmental advantages.