Product Description
In the chemical industry, kaolin powder is used as a filler and extender in various products, such as plastics, rubber, and adhesives. Its high whiteness and chemical inertness make it an excellent choice for these applications, enhancing the physical properties and aesthetic appeal of the final products.
Kaolin powder also plays a significant role in the coatings and painting industries. It is used as a pigment extender and rheology modifier, improving the coverage, durability, and texture of paints and coatings. Its ability to enhance the opacity and hide imperfections in surfaces makes it a valuable addition to these formulations.
In the rubber industry, kaolin powder is used as a reinforcing filler, improving the tensile strength, abrasion resistance, and dimensional stability of rubber products. Its fine particle size and high surface area contribute to better dispersion and bonding within the rubber matrix.
In conclusion, kaolin powder is a versatile and essential ingredient in multiple industries, contributing to the production of high-quality products with enhanced physical and aesthetic properties. Its wide range of applications underscores its importance in modern manufacturing processes.
| Place of Origin |
China |
| Color |
White/Yellow |
| Shape |
Powder |
| Purity |
90-99% |
| Grade |
Industrial Grade Cosmetics grade |
| Package |
25kg/bag，customized package |
| MOQ |
1kg |
The rubber industry constantly seeks innovative reinforcing fillers to enhance product performance, extend service life, and optimize production costs. In this context, calcined kaolin powder has emerged as a versatile and reliable additive, revolutionizing the manufacturing of various rubber products, including tires, hoses, gaskets, and conveyor belts. Unlike traditional fillers such as carbon black, which can darken rubber compounds, or silica, which often requires complex dispersion processes, calcined kaolin powder offers a unique combination of benefits. Its natural white color makes it ideal for applications where aesthetics matter, while its exceptional reinforcing properties and enhanced aging stability ensure superior performance across both black and colored rubber applications.
Tear resistance stands as a critical performance metric for rubber products subjected to repeated stress and mechanical strain, such as tires and conveyor belts. Calcined kaolin powder, processed at temperatures ranging from 800 to 1000°C, boasts a highly porous structure that significantly increases its surface area to an impressive 20 - 30 m²/g. This unique microstructure enables the powder to form strong interfacial bonds with rubber polymer chains, acting as a reinforcing network within the compound.
According to comprehensive tests conducted by a leading Japanese tire manufacturer, when incorporated at a concentration of 15% - 25% of the rubber weight into natural rubber (NR) tire treads, calcined kaolin powder can boost tear strength by an astonishing 30% - 40%. Specifically, the tear strength of the treads increased from 25 kN/m to 32.5 - 35 kN/m, translating into a substantial reduction in tread wear. Under normal driving conditions, this enhancement extends the lifespan of tires by approximately 15%, offering significant cost savings to consumers and fleet operators alike.
In the case of rubber hoses used in construction equipment, the addition of calcined kaolin powder provides enhanced resistance to kinking and tearing. Rigorous testing revealed that hoses formulated with 20% calcined kaolin powder could withstand an impressive 100,000 bending cycles with a radius of 50 mm without developing any cracks. In contrast, unreinforced hoses failed after only 60,000 cycles. This remarkable improvement in durability ensures the reliable operation of construction equipment, minimizing downtime and maintenance costs.
Furthermore, the inherent white color of calcined kaolin powder makes it the filler of choice for colored rubber products. In applications such as rubber gaskets for food processing equipment (non - direct contact) and decorative rubber mats, where the use of carbon black would compromise the visual appeal, calcined kaolin powder allows manufacturers to create aesthetically pleasing products without sacrificing performance.
Aging stability is another crucial aspect of rubber product performance, especially for items exposed to harsh environmental conditions such as heat, oxygen, and ozone. Over time, these factors can cause rubber to harden, crack, and lose its elasticity, leading to premature failure. Calcined kaolin powder's high alumina content, typically ranging from 40% - 45%, combined with its low impurity levels (iron ≤0.2%, titanium ≤0.1%), provides excellent resistance to oxidative degradation.
The powder's porous structure acts as a barrier, effectively trapping free radicals generated by heat and oxygen, preventing them from attacking and breaking down the rubber chains. Accelerated aging tests conducted in accordance with ASTM D573 standards demonstrated that ethylene - propylene - diene monomer (EPDM) rubber compounds containing 20% calcined kaolin powder retained 80% of their original elongation at break after 5000 hours at 120°C. In comparison, unreinforced EPDM rubber retained only 55% of its original elongation, highlighting the significant improvement in aging resistance.
For rubber conveyor belts used in the mining industry, where exposure to ozone is a major concern, calcined kaolin powder offers exceptional protection. Belts formulated with 15% kaolin powder showed no signs of cracking after 1000 hours of exposure to ozone at a concentration of 50 ppm and a temperature of 40°C. In contrast, belts without kaolin powder exhibited severe cracking, underscoring the powder's effectiveness in enhancing ozone resistance. This extended aging stability not only reduces the frequency of belt replacements but also minimizes costly downtime for mining operations.
The production of calcined kaolin powder for rubber applications is a meticulous process that involves several key stages. It begins with the beneficiation of raw kaolin ore, which is washed and subjected to magnetic separation to remove impurities. The purified ore is then crushed into small chunks, typically 5 - 10 mm in size, before undergoing calcination in rotary kilns at temperatures between 800 and 1000°C. This calcination process removes hydroxyl groups from the kaolin structure, transforming it into a porous, anhydrous material known as metakaolin, which exhibits enhanced reinforcing properties.
Following calcination, the material is ground using dry grinding techniques, typically with air classifier mills, to achieve a specific particle size ranging from 325 - 1250 mesh (D50 10 - 30 μm). Sieving is then carried out to eliminate any coarse particles, ensuring a consistent and uniform product. For applications that require even better dispersion within rubber compounds, the calcined kaolin powder can undergo surface treatment with stearic acid or silane coupling agents at a dosage of 0.5% - 1%. This treatment improves the compatibility between the powder and rubber resins, further enhancing the overall performance of the final product.
Key technical indicators play a vital role in ensuring the quality and performance of calcined kaolin powder for rubber applications. These include a particle size D50 of 10 - 30 μm (325 - 1250 mesh), a whiteness (L* value) of ≥88%, a surface area of 20 - 30 m²/g, a moisture content of ≤0.3%, and an oil absorption of 35 - 45 mL/100g. Rigorous testing methods are employed to measure these parameters, including laser particle size analyzers for particle size determination, BET surface area analyzers for surface area measurement, and thermogravimetric analysis for moisture content assessment.
To ensure compliance with international rubber industry standards, such as ISO 4098 (rubber and rubber products—determination of composition), the production process is carefully monitored, and strict quality control measures are in place. The calcined kaolin powder is free from toxic additives and has a low heavy metal content, making it a safe and environmentally friendly choice for rubber manufacturing.
In addition to its technical properties, the supply chain and technical support for calcined kaolin powder are designed to meet the specific needs of the rubber industry. Packaging options are available to suit different customer requirements, including 25kg paper bags with inner polyethylene liners for smaller orders and 1000kg bulk bags for large - scale rubber manufacturers. Anti - caking agents are added to prevent particle agglomeration during storage and transportation, ensuring the powder remains free - flowing and easy to handle.
Delivery times are optimized to minimize lead times, with regional customers, such as those shipping from Thailand to Malaysia, typically receiving their orders within 10 - 15 days. International shipments, for example, from Australia to Europe, are delivered within 25 - 35 days. A dedicated technical team is on hand to provide comprehensive formulation guidance, offering tailored recommendations based on specific application requirements. For instance, they recommend using 20% of 1250 - mesh calcined kaolin powder for high - performance EPDM gaskets to maximize aging stability, while suggesting 15% of 325 - mesh powder for rubber mats to strike the right balance between cost and tear resistance.
As the rubber industry continues to evolve, driven by the demand for more durable, high - performance, and aesthetically appealing products, calcined kaolin powder is poised to play an increasingly important role. Its unique combination of properties, including enhanced tear resistance, improved aging stability, and the ability to maintain a white color, makes it an indispensable ingredient for rubber manufacturers looking to stay competitive in a global market. By leveraging the benefits of calcined kaolin powder, manufacturers can not only meet but exceed customer expectations, delivering rubber products that are both reliable and visually appealing while also optimizing production costs.
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