Light Calcium Carbonate for Rubber

Light Calcium Carbonate for Rubber

Light Calcium Carbonate, also known as Precipitated Calcium Carbonate (abbreviated as PCC), is produced through chemical processing methods. It is called "light" calcium carbonate because its sedimentation volume (2.4-2.8 mL/g) is larger than that of ground calcium carbonate produced by mechanical methods (1.1-1.9 mL/g). Its chemical formula is CaCO₃. It reacts with all strong acids to generate corresponding calcium salts (such as calcium chloride, CaCl₂) and release carbon dioxide. At room temperature (25°C), the solubility product of light calcium carbonate in water is 8.7/10²⁹, with a solubility of 0.0014. The pH value of an aqueous solution of light calcium carbonate ranges from 9.5 to 10.2, while the pH value of an air-saturated aqueous solution of light calcium carbonate ranges from 8.0 to 8.6. Light calcium carbonate is non-toxic, odorless, and non-irritating. It is typically white, with a relative density of 2.7 to 2.9, a sedimentation volume of over 2.5 mL/g, and a specific surface area of approximately 5 m²/g.

Application in the rubber industry

Calcium carbonate is one of the earliest and most widely used fillers in the rubber industry. When added in large quantities to rubber, it increases the volume of the product, thereby saving expensive natural rubber and reducing costs. The incorporation of calcium carbonate into rubber results in higher tensile strength, abrasion resistance, and tear strength compared to pure rubber vulcanizates. It also exhibits a significant reinforcing effect in both natural and synthetic rubber, while simultaneously allowing for viscosity adjustment.