When magnesium hydroxide is heated at 340 ℃-490 ℃, it will decompose and absorb the heat on the surface of the combustion product, thus playing the role of flame retardant. At the same time, it will release a large amount of water to dilute the oxygen on the surface of the combustion, and the active magnesium oxide generated by decomposition will adhere to the surface of the combustible, further preventing the combustion.

Secondly, magnesium hydroxide in the whole flame retardant process not only does not produce any harmful substances, and magnesium hydroxide decomposition products in the flame retardant effect at the same time, but also can absorb a large number of plastics, rubber and other polymer combustion smoke and harmful gases, active magnesium oxide can continue to absorb the incomplete combustion of the melting residue, and then make the combustion quickly stop, and eliminate the smoke and prevent droplets, is a new environmentally friendly inorganic flame retardant.

According to the chemical composition, flame retardants can be divided into two categories: organic flame retardants and inorganic flame retardants. Organic flame retardants are divided into two series of halogen and phosphorus. Because organic flame retardants have defects such as large smoke and high toxicity of decomposition products, they are gradually being replaced by inorganic flame retardants.

The main varieties of inorganic flame retardants are magnesium hydroxide, aluminum hydroxide, tin oxide, antimony oxide, molybdenum oxide, red phosphorus, zinc borate, ammonium molybdate and so on. Among them, magnesium hydroxide and aluminum hydroxide have a large amount of heat absorption due to decomposition, and the generated H2O can play a role in isolating the air, and the oxide generated after decomposition is a high-temperature resistant substance, so magnesium hydroxide and aluminum hydroxide, the two flame retardants, can not only play a role in flame retardancy, but also play a role in filling, and have the characteristics of not producing corrosive halogen and harmful gases, smokeless, non-toxic, non-dripping, non-dripping, non-volatilizing, non-volatilizing, non-volatilizing, long.

At present, the amount of aluminum hydroxide in China is more, but with the increase of polymer processing temperature, aluminum hydroxide is easy to decompose and reduce the flame retardant effect. Therefore, magnesium hydroxide gradually replaced aluminum hydroxide. Compared to aluminum hydroxide, magnesium hydroxide has the following advantages:

(I) The decomposition temperature of magnesium hydroxide is 100 ℃ higher than that of aluminum hydroxide, reaching 330 ℃, which is more helpful to improve the processing temperature of plastics, accelerate the extrusion speed and shorten the molding time;

(II) Magnesium hydroxide has high decomposition energy, which helps to absorb combustion heat and improve flame retardant efficiency;

(III) magnesium hydroxide and acid neutralization ability, can quickly neutralize the plastic in the combustion process of acid gas CO2, SO2, NOX, etc;

(IV) Magnesium hydroxide has low hardness, strong smoke suppression ability, and low friction to equipment, which is beneficial to prolong the service life of production equipment.