The Application of Calcium Carbonate in Plastics
Calcium carbonate (CaCO₃) is the most widely used and largest-volume inorganic filler and modifier in the plastic industry. With advantages such as low cost, abundant sources, environmental friendliness, non-toxicity, and high whiteness, it primarily serves dual functions of "cost reduction through filling" and "performance optimization" in plastics. Its applications span multiple fields including general-purpose plastics, engineering plastics, and biodegradable plastics, with specific usage details as follows:
The specific applications of calcium carbonate in various types of plastics
Polyvinyl chloride (PVC) plastics (core application areas)
1. Application characteristics:
Calcium carbonate is the largest filler used in PVC, suitable for hard and soft PVC and PVC paste. Its core function is to reduce costs, increase efficiency, optimize processing performance and product stability.
2. Specific scenario:
Hard PVC (such as pipes, profiles, floor leather): mainly using 400-800 mesh heavy calcium, used to reduce costs, improve dimensional stability, and reduce shrinkage deformation; High end products (such as precision accessories) use activated calcium carbonate to enhance compatibility and surface quality.
Soft PVC (such as film, synthetic leather, cable sheath): mainly uses light calcium to reduce costs, improve surface gloss, and adjust paste viscosity; After surface modification, the dispersibility of light calcium can be improved and the oil absorption value can be reduced.
PVC film and cable material: Use 800~1250 mesh heavy calcium or light calcium to improve the transparency, toughness, and electrical insulation of the film and cable material.
Polyolefin plastics (PE, PP)
1. Application characteristics:
Calcium carbonate is mainly used as a filler in polyolefins to reduce costs, improve processing flowability, enhance rigidity and heat resistance. In some scenarios, it can be used as a nucleating agent (such as PP) or to improve breathability (such as PE breathable film).
2. Specific scenario:
PE plastics (such as films, pipes, calcium plastic products): using heavy calcium or light calcium to reduce costs and improve processing flowability; PE film with added heavy calcium (such as shopping bags) can still meet the mechanical performance requirements when 30% is added; PE breathable membrane achieves breathable function through the microporous structure of calcium carbonate.
PP plastics (such as injection molded parts, woven bags, and home appliance casings): using heavy calcium, light calcium, or ultrafine/nano calcium to improve rigidity, heat resistance, and dimensional stability; A medium filling amount (20%~30%) can significantly improve impact resistance, while a high filling amount (30%~40%) is used for cost sensitive products such as plastic pallets.
Other plastics (such as PP, PE, PA, ABS, etc.)
PA (Nylon) plastic: using active ultrafine calcium carbonate to improve processing flowability, reduce water absorption, enhance dimensional stability and wear resistance.
ABS plastic: uses light calcium or activated calcium carbonate to reduce costs, improve processability, surface glossiness, and enhance rigidity.
Thermosetting plastics (such as epoxy resin): Use ultra-fine light calcium or activated calcium carbonate to adjust resin viscosity, improve molding processability, and enhance hardness.
The core role of calcium carbonate in plastics
1. Cost reduction and efficiency improvement: The price of calcium carbonate is much lower than that of plastic resin, and a large amount of filling can replace plastic raw materials, significantly reducing overall costs while reducing resin usage, making it suitable for controlling costs in large-scale production.
2. Improve processing performance: Moderate addition can reduce the viscosity of plastic melt, decrease machine torque, improve processing fluidity, shorten cooling cycle, enhance production efficiency, and reduce mold wear.
3. Optimize physical and mechanical properties: improve the rigidity, hardness, heat resistance, and dimensional stability of plastics, reduce the coefficient of thermal expansion, and enhance wear resistance and impact resistance.
4. Optimize appearance and functionality: High whiteness calcium carbonate can improve product whiteness and reduce the amount of titanium dioxide used; By filling to form micropores, breathable function can be achieved; High filling content contributes to the environmentally friendly degradation of plastics.
The selection logic of calcium carbonate
The selection of calcium carbonate needs to be matched according to the plastic variety, product performance requirements, and cost budget:
Heavy calcium carbonate (GCC): The lowest cost, suitable for general filling (such as PVC pipes, ordinary PE/PP products), mainly for incremental cost reduction and size stability.
Lightweight calcium carbonate (PCC): with fine particles and good reinforcement effect, it is suitable for products with certain requirements for mechanical properties (such as PP injection molded parts and high-end PVC films).
Activated/ultrafine/nano calcium carbonate: After surface modification or extremely fine particle size, it has excellent compatibility and is suitable for high-end plastic products (such as automotive plastic parts, precision injection molded parts, high-end films). It can significantly improve mechanical properties and surface smoothness, but the cost is relatively high.