Magnesium hydroxide is a white crystal or powder, slightly soluble in water, widely used as a flame retardant. Magnesium hydroxide has flame retardant properties because: it decomposes above 340 ℃, generating magnesium oxide and water, absorbing heat from the surface of the burning material. Generate a large amount of water has dilution and isolation of air (oxygen) on the surface of combustible materials, decomposition of the generated active magnesium oxide solid is high temperature resistant material, attached to the surface of combustible materials to further prevent combustion. Decomposition of magnesium hydroxide does not produce corrosive and toxic gases, and it is alkaline, can absorb and neutralize the acidic gases released during combustion, such as carbon dioxide, sulfur dioxide and nitrogen oxides, decomposition of the generated active magnesium oxide can also absorb the harmful gases generated during combustion, smoke and incomplete combustion of molten residues, eliminate smoke, so that the process of molten droplets to stop, so as to achieve the purpose of flame retardant.