The combustion and flame retardancy of substances are very complicated processes, involving many influences and constraints. We can idealize the flame retardant mechanism of flame retardants into the following three types: 1. The flame retardant materials are heated or burned to generate free radical inhibitors, which interrupts the combustion chain reaction. 2. Fire-retardant materials generate fine particles when heated or burned, which promotes the mutual binding of free radicals and causes the termination of combustion. 3. A large amount of inert gas or high-density steam is generated when the flame retardant material is heated or burned, which plays the role of diluting and isolating the combustible gas or lowering the temperature, leading to the termination of combustion.

Condensed phase flame retardant In the condensed phase, the flame retarding effect that retards or interrupts the thermal decomposition of combustible materials, such as phosphorus flame retardants. Flame retardants retard or prevent the generation of flammable gases and free radicals in the solid phase. Inorganic fillers with large specific heat capacity in flame retardant materials make it difficult for the material to reach the thermal decomposition temperature through heat storage and heat conduction. When the flame retardant materials decompose, it absorbs external heat and causes the external temperature to decrease. When the flame retardant materials burn, a flame retardant barrier is formed on the surface. A porous carbon layer that is thermally isolated from oxygen, resulting in interrupted combustion.

The evaluation of leather flammability usually uses the vertical combustion test method and the aerobic index test method. Although these two methods still have some limitations. But it works, and to a certain extent, they can complement each other. For the specific test method of the vertical combustion test method, refer to the American Leather Chemist's Standard on Fire Performance, which is simply "it is an ignition test. Its purpose is to measure the time required for the flame to extinguish when the combustion source is removed and the embers The time required for complete extinction, and at the same time the remaining length of the sample after burning and the percentage of weight loss are measured. The smaller these parameters are, the better the fire resistance of the leather.