Why is CaCo3 powder added to plastic pellets?

CaCO3 powder, also known as calcium carbonate powder, is commonly added to plastic pellets for several reasons:

1. Cost reduction: CaCO3 powder is an inexpensive filler material compared to pure plastic resin. By incorporating CaCO3 powder into plastic pellets, manufacturers can reduce the amount of expensive plastic resin required while maintaining the bulk volume of the plastic. This helps to lower the production cost of plastic products.

2. Improved mechanical properties: CaCO3 powder can enhance the mechanical properties of plastic materials. When added in appropriate amounts, it can increase the stiffness, strength, and impact resistance of the resulting plastic products. The presence of CaCO3 powder can improve the dimensional stability and reduce shrinkage of plastic parts during processing and use.

3. Density adjustment: The addition of CaCO3 powder allows manufacturers to adjust the density of plastic products. CaCO3 is a high-density material compared to most plastic resins. By adding it to plastic pellets, the overall density of the resulting plastic can be increased or decreased, depending on the desired application. This can be beneficial for achieving specific weight requirements or balancing the weight distribution of plastic products.

4. Processing improvement: CaCO3 powder can act as a processing aid during the plastic manufacturing process. It helps to improve the flow properties of the molten plastic, facilitating better mold filling and reducing the chances of defects such as voids or sink marks. The presence of CaCO3 powder can also help to control the cooling rate of the plastic, preventing warping or deformation after molding.

5. Environmental benefits: The addition of CaCO3 powder to plastic pellets can contribute to the reduction of carbon footprint. Due to its lower cost and availability, CaCO3 powder is often used as a filler material instead of relying solely on plastic resins. This approach reduces the consumption of fossil fuel-based plastics and promotes a more sustainable use of resources.

6. Improvement of heat resistance of plastic products: Adding CaCo3 powder to common plastic products can improve the heat resistance of plastic products. If about 40% of CaCo3 powder is added to PP, its heat resistance can be increased by about 200℃. When the filling rate is less than or equal to 20%, the heat resistance can be increased by 8~130℃.

7. Improve the light diffusion of plastics: Calcium carbonate powder with whiteness above 90 has obvious whitening effect in plastic products. In calcium plastic paper, in low-density polyethylene and high-density polyethylene film, the addition of calcium carbonate powder can achieve the effect of light diffusion and extinction, making it suitable for writing and printing. Calcium carbonate powder with better whiteness can also replace expensive white pigments.

8. It can make the products have some special properties: adding calcium carbonate powder can improve the plating and printing performance of some products. Adding trace amount of calcium carbonate powder in PVC has certain flame retardant effect.

It’s important to note that the specific amount of CaCO3 powder added to plastic pellets and the desired effects may vary depending on the application, required properties, and the type of plastic being used. Manufacturers conduct thorough testing and formulation adjustments to achieve the desired performance and cost-efficiency in their plastic products.

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