The Principle and Applications of Flame-Retardant Aluminum Hydroxide

Aluminum hydroxide trihydrate (ATH) is a flame retardant. Its mechanism involves releasing crystalline water upon thermal decomposition. This strongly endothermic reaction absorbs significant heat, cooling the polymer matrix.

Aluminum hydroxide trihydrate (ATH) is a flame retardant. Its mechanism involves releasing crystalline water upon thermal decomposition. This strongly endothermic reaction absorbs significant heat, cooling the polymer matrix. Simultaneously, the generated water vapor dilutes combustible gases and suppresses flame propagation.

The novel refractory metal oxide Al₂O₃ exhibits high reactivity. It catalyzes the thermal-oxidative cross-linking reaction of polymers, forming a carbonized film on the polymer surface. This carbonized film impedes heat and mass transfer during combustion, thereby achieving flame retardancy. Al₂O₃ also adsorbs soot particles, effectively suppressing smoke generation.

The chemical formula for flame-retardant aluminum hydroxide is Al(OH)₃, representing aluminum hydroxide. Aluminum hydroxide reacts with acids to form salts and water, and with strong bases to form salts and water, making it an amphoteric hydroxide. Due to its acidic properties, it is also known as aluminate (H₃AlO₃).

Flame-retardant aluminum hydroxide prevents melt dripping, promotes carbonization, is non-volatile, non-leaching, and remains stable in polymers over extended periods. It offers advantages such as non-toxicity, excellent stability, and no toxic gas emission at high temperatures, while reducing smoke and soot during plastic combustion. Its low cost and broad applicability further enhance its value.

The dehydration endothermic temperature of flame-retardant aluminum hydroxide is relatively low, ranging from approximately 235 to 350°C, delivering significant flame-retardant effects during initial combustion. When 40% ATH is added, it significantly lowers the thermal decomposition temperature of PE (polyethylene), PP (polypropylene), PVC (polyvinyl chloride), and ABS (acrylonitrile butadiene styrene copolymer), while delivering excellent flame retardancy and smoke reduction.

In Japan, polyolefins containing 50% aluminum hydroxide are primarily used for manufacturing food packaging materials. Flame-retardant polyolefins containing 60% aluminum hydroxide can serve as construction materials and interior decoration materials for automobiles and ships.