Full definition
Carbon black is a crucial reinforcing filler extensively used in the rubber industry, derived from the incomplete combustion or thermal decomposition of hydrocarbons such as oil or gas. Its unique properties significantly enhance the performance of rubber compounds, making it a preferred choice for various applications, particularly in tires. The addition of carbon black can increase tensile strength by 2 to 5 times, while also improving abrasion resistance by 5 to 10 times, tear resistance, and providing UV protection. This material is classified according to ASTM D1765 based on particle size and structure, which is vital for determining its suitability for specific rubber applications.
The classification ranges from N110-N121, which are super abrasion furnace blacks with the finest particles (15-25 nm) that offer the highest reinforcement suitable for tire treads, to N762-N990, which are thermal blacks with larger particles (200-500 nm) that provide minimal reinforcement and are predominantly used as fillers to reduce costs. The intermediate grades, such as N220-N234, strike an excellent balance of properties, making them ideal for belts and hoses, while N330 serves as a general-purpose grade suitable for various applications.
Typically, the dosage of carbon black in rubber compounds varies from 30 to 80 parts per hundred rubber (phr), depending on the specific performance requirements of the application. The effectiveness of carbon black can also be evaluated through ASTM D1510, which assesses iodine adsorption, and ASTM D2414, which measures structure and dibutyl phthalate (DBP) absorption. Additionally, certain grades of carbon black can render rubber electrically conductive, making them suitable for antistatic applications. The global production of carbon black stands at approximately 15 million tonnes per year, with the tire industry accounting for over 70% of this production, underscoring its critical role in the automotive sector and beyond.