The Key Role of Calcium Carbonate in the Plastic Industry

The Characteristics of Calcium Carbonate

Calcium carbonate is categorized into heavy and light types, serving as the most widely used inorganic filler in plastics. Its functions encompass four key dimensions: cost coverage, processing, performance, and appearance.

Cost Reduction and Efficiency Improvement (Core Economic Role)

1. The price of calcium carbonate is much lower than that of resins such as PE, PP, PVC, etc., and a large amount of filling replaces plastic raw materials, greatly reducing the overall cost of raw materials;
2. Calcium carbonate has a high density under the same volume, which can reduce the amount of resin used and is suitable for controlling costs in large-scale production of films, pipes, and injection molded parts.

Improve Processing Fluidity and Formability

1. Adjust melt flowability: Adding an appropriate amount can reduce the viscosity of plastic melt, decrease the torque of extrusion and injection molding machines, save electricity, improve extrusion/injection speed, and increase production efficiency;
2. Anti shrinkage and good shaping: suppresses shrinkage, warping, and deformation of plastic after molding, improves the dimensional stability of products, especially injection molded shells, plates, and fittings;
3. Smoother demolding: Inorganic powder lubricates the mold cavity, reducing product sticking and lowering defect rates;
4. Shorten the cooling cycle and increase production line capacity.

Improve the Physical and Mechanical Properties of Products

1. Improve rigidity and hardness: Pure plastic tends to be soft, and after filling with calcium carbonate, the bending modulus and surface hardness significantly increase, making it suitable for packaging tapes, plastic sheets, and home appliance casings;
2. Improve heat resistance: Calcium carbonate has good thermal stability and increases the plastic's thermal deformation temperature, making the product less prone to softening and deformation at high temperatures;
3. Wear resistant and scratch resistant: After the powder is evenly dispersed, the surface of the product is resistant to friction and not easily scratched;
4. Reduce the coefficient of thermal expansion: reduce the deformation caused by temperature changes and improve the accuracy of precision plastic parts;
5. To a certain extent, it improves the compressive and creep resistance, and is not easily deformed under long-term load-bearing.

Optimize Appearance and Surface Characteristics

1. Matte effect: replacing chemical matting agents, achieving a low-cost matte surface on plastics, suitable for packaging films and home appliance casings;
2. Adjust whiteness and coverage: High white calcium carbonate enhances product whiteness, reduces the amount of titanium dioxide added, and further reduces costs;
3. Improve printing and adhesion: Pure plastic surfaces are inert and difficult to print, calcium carbonate increases surface micro roughness, and ink and glue adhesion is stronger;
4. Reduce surface shrinkage marks and water ripples on the product, and improve its appearance smoothness.

Functional Modification (Key Role in Special Scenarios)

1. Breathable modification (film specific): After stretching the PE film filled with calcium carbonate, micropores are formed at the interface between the powder and resin to produce breathable films (sanitary napkins, fresh breathable bags);
2. Environmental degradation assistance: Highly filled calcium carbonate film, more prone to brittleness and photo oxidative degradation after disposal, reducing plastic residue;
3. Oil absorption and adsorption aids: adsorb small amounts of small molecule plasticizers and volatiles in plastics to reduce processing smoke and product frosting;
4. Flame retardant assistance: high temperature decomposition releases CO ₂, dilutes combustible gases, absorbs heat and cools down, and is combined with flame retardants to reduce flame retardant costs;
5. Sound and heat insulation: After a large amount of filling, a fine interface is formed inside to block sound waves and heat, which is used for plastic sound insulation boards and insulation profiles.