1. Produce a gas that can suppress the flame. Like antimony trioxide, when it encounters HCL emitted by burning in PVC
2. Absorb the heat generated during combustion and play the role of cooling to slow down the burning rate. Like aluminum hydroxide, the proportion of chemical association water contained in its molecules is as high as 34%. This association water remains stable at the processing temperature of most plastics, but begins to decompose when it exceeds 200 ° C, releasing water vapor. And for every mole of aluminum hydroxide decomposed, 36 kilocalories of heat are absorbed.
3. Provide a layer of coating isolated from oxygen. For example, the phosphide generated when the phosphate ester flame retardant is burned is the oxygen barrier coating.
4. Generate free radicals that can react with plastics and play a flame retardant role. The combustion performance of their reaction products with plastics is extremely poor.
According to different methods of use, flame retardants can be divided into additive type and reactive type. Additive flame retardants mainly play the role of flame retardants by adding flame retardants to combustible materials. The reactive flame retardant introduces flame retardant groups into the polymer material through chemical reaction, thereby improving the flame resistance of the material, preventing the material from being ignited and suppressing the spread of flame. Among the types of flame retardants, additive flame retardants dominate, and the range of use is relatively wide, accounting for about 85% of the flame retardants, and reactive flame retardants only account for 15%.