Innovative application of high-filled calcium carbonate in polymer products
In recent years, with the continuous advancements in high-filling and efficient dispersion technologies, the application of calcium carbonate in polymers is moving towards high performance, functionalization, greenification, and cost reduction, demonstrating significant development potential.
1. New trends in research and application of calcium carbonate
High-filled calcium carbonate technology has achieved the dual goals of "performance improvement" and "cost reduction", and further needs to transition from "passive filling" to "active functionalization".
Research has found that the interfacial characteristics formed between calcium carbonate powder and polymers are a key issue in composite material research and a technological breakthrough for active functionalization transformation. Their interfacial characteristics directly affect the mechanical properties, thermal stability, electrical conductivity, thermal conductivity, and other functional characteristics of composite materials.
2. Interfacial reinforcement mechanism of calcium carbonate and polymer
From this, it can be inferred that the key research content in the application of calcium carbonate in polymers remains the interface reinforcement mechanism, stress concentration effect, pinning-climbing effect, interface voiding, and factors affecting interface characteristics (such as bonding strength and particle size/dispersibility).
Interface bonding strength: The key to the toughening effect of calcium carbonate on plastics lies in the interface bonding strength between calcium carbonate and plastics. Traditional acid ester coupling agents, fatty acid salts, and grafted materials can enhance the interface bonding strength, but they are still subject to limitations.
Particle size and dispersibility: Nanoscale calcium carbonate has a larger specific surface area, but the agglomeration problem needs to be addressed; ultrafine calcium carbonate has a significant reinforcing effect on materials, but it can also change processing characteristics; larger particle size calcium carbonate is relatively convenient for processing, but the performance of the product may be compromised.
There is still ample room for expansion in both depth and breadth of current research outcomes, and high value-added products are continuously emerging.
3. Application of calcium carbonate in polymers
Calcium carbonate, as a functional filler, can significantly enhance the mechanical properties and processing performance of polymer products, while reducing costs. It is widely used in plastics, rubber, and other fields.
Plastic
Calcium carbonate is one of the lowest-priced fillers, featuring non-toxicity, non-irritation, odorlessness, high whiteness, and moderate hardness.
When CaCO3 powder is added to plastics, it serves as a filler on the one hand, increasing the volume of the plastic and reducing costs; on the other hand, it can improve various properties of the plastic, such as enhancing the thermal stability, toughness, and hardness of plastic products, and improving the light scattering property to achieve shading and matting effects. In addition, CaCO3/PBAT/PLA composite materials exhibit compatibility, have the potential for blending modification, and possess both toughness and degradability, making calcium carbonate one of the mainstream filler modification materials for degradable plastics.
Rubber is widely used in transportation, machinery, electronics, national defense, and other fields of the national economy. However, rubber also has its own obvious disadvantages, such as small intermolecular forces, large free volume, and poor self-crystallization ability, which lead to low strength and modulus, and poor wear resistance of rubber materials. Therefore, it is necessary to add inorganic non-metallic filler materials to meet the requirements of applications.
Calcium carbonate is one of the primary fillers and reinforcing agents used in the rubber industry. Among them, ground calcium carbonate (GCC) is primarily used as a filler to reduce costs; precipitated calcium carbonate (PCC) possesses semi-reinforcing properties and can enhance the physical and mechanical properties of vulcanized rubber; nano-calcium carbonate and modified calcium carbonate exhibit superior reinforcing properties and also have color-adjusting and whitening effects, making them partial substitutes for expensive materials such as silica and titanium dioxide. Overall, in the future, the development of calcium carbonate used in rubber will gradually shift from GCC or PCC towards nano-calcium carbonate and modified calcium carbonate.
From the perspective of the dosage and scope of fillers in rubber products, calcium carbonate is indispensable. Furthermore, with the continuous breakthroughs in high-filling and high-dispersion technologies, the advantages of calcium carbonate, such as its production capacity, cost efficiency, and variety, will be further leveraged.
Tyre - The amount of tread carbon black is 40-50 parts. Basically, no non-reinforcing fillers are used, or a small amount of clay is used. About 20 parts of clay or light calcium carbonate can be used in the inner tube rubber.
Rubber belt - Carbon black can be used in an amount of 25 to 45 parts. Calcium carbonate can be used in various components, with an amount of 10 to 113 parts. Magnesium carbonate can be used for flat belt sealing glue and edge glue paste, with amounts of 40 parts and 50 parts respectively. Barium sulfate is used for flat belt rubbing glue, with an amount of 25 parts.
Rubber hose - The amount of carbon black used is 15 to 45 parts. The amount of calcium carbonate used is 33 to 128 parts, the amount of clay used is 20 to 50 parts, the amount of magnesium carbonate used is 25 parts, and 30 parts of barium sulfate is also used in acid and alkali transport hoses.
Rubber shoes - For black soles, use 50 parts of carbon black, 50 parts of ultra-fine activated calcium carbonate (Baiyanhua), 40 parts of clay. For white soles, use 55 parts of white carbon black, 15 parts of ultra-fine calcium carbonate, and 2 parts of titanium dioxide.
Rubberized fabric products - Calcium carbonate and clay can be used in various rubberized fabric products, with a dosage of 30 to 150 parts. Barium sulfate is used for airtight rubberized fabric, with a dosage of 11 parts. Model products - Carbon black can be used in an amount of 40 to 75 parts. White carbon black can be used in an amount of 30 parts, clay can be used in an amount of 35 parts, and calcium carbonate can be used in an amount of 20 parts.
Sealing products - 70 parts of silica can be used for oil seals. For sealing strips, use 25 parts of carbon black, 10 parts of calcium carbonate, 30 parts of clay, and 40 parts of carbon black for oil-resistant vacuum sealing. For diaphragms, use 15 parts of carbon black and 54 parts of calcium carbonate.
Latex products - Latex gloves can be made with 10-15 parts of barium sulfate or 5 parts of calcium carbonate. In sponge latex formulations, 20 parts of talcum powder can be used. In neoprene latex yarn formulations, 2-3 parts of clay can be used. In porous model latex formulations, 100 parts of clay or 100-300 parts of calcium carbonate can be used.
