P‐N‐Al Synergistic System for Constructing Low‐Hardness, High‐Wear‐Resistance, and Flame‐Retardant Conveyor Belts

Flame‐retardant rubber materials for conveyor belts have long relied on traditional halogen/antimony flame‐retardant systems, which tend to increase hardness and reduce abrasion resistance. In this study, a natural rubber/polybutadiene rubber (NR/BR) composite with low hardness, high abrasion resistance, and adequate flame retardancy was developed. A phosphorus/nitrogen/aluminum (P/N/Al) synergistic flame‐retardant system based on halogen‐free aluminum diethylphosphinate (ADP) and melamine (MEL) was constructed, together with a phosphorus‐based plasticizer, tris(isopropylphenyl) phosphate (IPPP‐95), to improve processability and mechanical properties. As a result, an NR/BR composite with excellent overall performance was successfully prepared. Compared with the conventional chlorinated paraffin/antimony trioxide system, the NR/BR/L40 formulation (containing 40 phr of Longsafe 207) maintained a Shore A hardness of approximately 50, significantly increased the limiting oxygen index (LOI) to 26.5%, achieved a UL‐94 HB rating (which is acceptable for conveyor belt applications), and exhibited a DIN abrasion loss of 194 mm 3 . This formulation successfully achieves a favorable balance among adequate flame retardancy, high abrasion resistance, and low hardness, providing a viable technical route for the development of high‐performance flame‐retardant conveyor belts for mining applications.