DPL DPOCAL is the most widely used filler in the plastics industry. Adding calcium carbonate (DPOCAL) eases the polymer extrusion and also lowers the cost. It enhances the heat resistance, stiffness and hardness of the polymer. Being white in color, DPOCAL (calcium carbonate) also helps in pigmentation and aids in enhancing or compensating for loss of gloss. In plastics it is extensively used in PVC (both rigid and flexible).