Introduction to Aminosulfonate Flame Retardants

Aminosulfonates are a type of sulfur derivative that plays an important role in PC flame retardants, primarily for treating cellulose materials. When used in combination with ammonium, aluminum, or other metal sulfates, they impart flame retardancy to cellulose materials. Some aminosulfonates can also be used to prepare durable flame-retardant materials. For example, in the presence of urea, using an impregnation-drying curing process, cellulose products treated with ammonium aminosulfonate can withstand repeated washing with hot alkaline water (including soft and hard water). The flame-retardant mode of aminosulfonated polymers differs from that of phosphorylated polymers. Compared to phosphorylated fibers, the crystalline regions of aminosulfonated fibers are more easily hydrolyzed during thermal cracking. The reduced crystallinity of cellulose decreases the amount of L-glucose, thus improving the flame retardancy of cellulose, or in other words, reducing the required flame retardant dosage.

Sulfation of polyamides can form reactive, durable flame-retardant systems. Many diamines and phosphorus- or halogenated dicarboxylic acids have been used to produce modified reactive flame-retardant polyamide fibers. However, these fibers suffer from deteriorated mechanical properties, poor hand feel, and high prices. In contrast, polyamides treated with low concentrations (1.5%2.5%) of ammonium aminosulfonate in the presence of pentaerythritol exhibit not only high flame retardancy but also a good hand feel and minimal degradation in mechanical properties. In these flame-retardant polyamides, the free amino groups undergo sulfation below 270°C and a second sulfation occurs at higher temperatures. The sulfation reaction and flame-retardant systems based on polymer sulfation are predicted to have significant potential applications.