Calcium carbonate (CaCO₃) is one of the most commonly used mineral fillers in the plastics industry. Thanks to its physical and chemical properties, it is added to polymer formulations to improve the final material's performance, reduce costs, and increase the stability of the extrusion process. Below are the main advantages and uses of calcium carbonate in plastic extrusion.
Advantages of Using Calcium Carbonate in Extrusion
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Cost reduction: Calcium carbonate is an inexpensive substance, which helps to lower the overall cost of plastic formulation, making it an economical option for manufacturers.
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Increased rigidity: Adding CaCO₃ increases the rigidity of the plastic material, making it suitable for applications requiring greater structural strength.
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Opacity and color: CaCO₃ enhances the opacity of the finished product, making it useful for products that require a matte finish. It also contributes a base white color, reducing the need for additional pigments.
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Dimensional stability: When added in appropriate amounts, CaCO₃ improves the dimensional stability of the product, reducing the risk of warping during and after extrusion.
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Efficiency in the extrusion process: Using CaCO₃ can improve material workability, facilitating flow during extrusion and allowing for faster and more uniform extrusion.
How to Use Calcium Carbonate in Extrusion
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Particle size selection: CaCO₃ is available in various particle sizes. Finer particle sizes are preferable for applications requiring a smooth surface finish, while larger particles can be used for less demanding applications.
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Correct dosage: The percentage of CaCO₃ to add varies depending on the application and type of polymer used. Concentrations usually range from 5% to 50% of total weight, but excessive dosing can compromise the final product's impact resistance.
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Polymer compatibility: To improve compatibility between CaCO₃ and the polymer, it is often necessary to use compatibilizing additives. These additives enhance adhesion between the filler and the polymer matrix, preventing separation and improving the quality of the final product.
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CaCO₃ drying: It is essential to ensure that calcium carbonate is well-dried before adding it to the extrusion mix, as residual moisture could negatively affect the process, causing defects in the final product.
Common Applications of Calcium Carbonate in Plastic Extrusion
CaCO₃ is widely used in the extrusion of various types of plastics, including:
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Films and sheets: Adding CaCO₃ makes plastic films more opaque and durable, as well as improving workability during extrusion.
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Pipes and profiles: In PVC pipes and profiles, CaCO₃ increases rigidity and dimensional stability while reducing raw material costs.
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Rigid packaging: Calcium carbonate is used to improve rigidity and reduce costs in rigid packaging, such as containers and bottles.
Final Considerations
Calcium carbonate is a valuable additive in the plastic extrusion industry. Its correct application allows not only for cost reduction but also improves physical properties and product quality. However, it is essential to carefully balance the amount of CaCO₃ in the formulation to avoid negative effects on the material's flexibility and strength.
