Basic function of flame retardant

Many plastics are thermostable materials. When it is heated in the air, degradation reactions often occur. Volatile gas evolved leaving porous residue. Residues are usually composed of carbon slag, which has the ability to absorb radiant heat, allowing it to accumulate warming. Oxygen in the air is also easily incorporated into the porous residue. When the concentration of oxygen and the temperature of the residue reach the combustion temperature of the volatile gas, the plastic will burn. This brings many limitations to plastic applications.

If substances such as phosphorus, halogen organic substances or antimony trioxide are added to the plastic to prevent or slow down its combustion, these substances are called flame retardants. In addition, in the synthesis of certain polymers (such as epoxy, polyester, polyurethane, abs, etc.), the introduction of some flame-retardant structures (groups), can also play a role in reducing its combustion properties, these are called reactive resistance Fuel.

Commonly used flame retardants are mostly compounds with element III, V, and VII elements (such as aluminum, nitrogen, phosphorus, antimony, chlorine, bromine, etc.), such as phosphoric acid esters (such as phosphoric acid diphenol ester and phosphoric acid trisulfite). Phenyl esters, toluene diphenyl phosphate, etc.), halophosphate esters [such as tris(2,3-dibromopropyl) phosphate], organic halides (such as chlorinated paraffins containing 70% chlorine, hexabromo Benzene, decabromodiphenyl ether, chlorinated biphenyl, etc.), inorganic flame retardants (eg, antimony trioxide, aluminum hydroxide v magnesium hydroxide, anhydrous hydrogen diamine, barium metaborate, zinc borate, red phosphorus, etc.) ).

The basic function of the flame retardant is to interfere with the three essential elements of maintaining combustion, oxygen, heat, and combustibles. Generally can achieve through the following path: 1 flame retardant can produce heavier non-flammable gas or high-boiling liquid, covering the plastic surface, the oxygen and flammable materials contact block. 2 Lower the surface temperature of the polymer by endothermic decomposition or endothermic sublimation of the flame retardant. 3 The flame retardant sentence produces a large amount of incombustible gas, diluting the combustible gas concentration and oxygen concentration in the combustion zone. 4 The flame retardant traps free radicals and interrupts the chain oxidation reaction.