(CaCO3) milled is one of the most popular mineral fillers used in the plastics industry. Calcium carbonate is widely available worldwide, easily milled or reduced to a specific particle size, compatible with a variety of polymer resins, and economical. As an additive in plastic compounds, CaCO3 helps reduce surface energy and imparts density and surface gloss, which improves surface finish. In addition, when particle size is carefully controlled, CaCO3 helps increase impact strength and flexural modulus (stiffness).

Calcium carbonate can be used with a wide range of thermoplastic resins. Polypropylene compounds are often filled with calcium carbonate to increase stiffness, an important requirement for operation at high temperatures. In PVC, calcium carbonate is used with flexible compounds such as pipe, wire and cable insulation, latex gloves, garbage bags and in rigid compounds such as extruded pipe, conduit and window profiles.