Hebei Messi Biology Co., Ltd. stated that basic magnesium carbonate has good thermal stability, is non-toxic, does not produce toxic or volatile gases, is inexpensive, and is an inorganic environmentally friendly flame retardant. Magnesium carbonate is an inorganic compound with a chemical formula of MgCO3, a molecular weight of 84.31, and a relative density of 3.037. It appears as a white granular powder. It decomposes at 350°C and loses carbon dioxide at 700°C. It is slightly soluble in cold water and slowly dissolves in acid. Its trihydrate is a colorless needle-shaped crystal with a melting point of 165°C and a relative density of 1.850. Its pentahydrate is a white monoclinic crystal with a relative density of 1.73, which decomposes when heated in the air. Hydrates can be obtained by passing carbon dioxide into a magnesium salt aqueous solution while adding sodium carbonate, and the anhydrous substance can be obtained by drying the hydrate below 50°C.
Basic magnesium carbonate (thermal decomposition temperature 220~550℃) has a wider thermal decomposition temperature range than magnesium hydroxide (thermal decomposition temperature 300~340℃) and aluminum hydroxide (thermal decomposition temperature 180~200℃). After combustion, basic magnesium carbonate decomposes and absorbs heat, releasing inflammable gas CO2 and water vapor, diluting the oxygen on the surface of the burning object and reducing the temperature of the surface of the burning object, and generating active magnesium oxide attached to the surface of the burning object to further prevent the combustion.
When magnesium carbonate is applied to flame-retardant epoxy resin, the oxygen index of epoxy resin reaches 29.7% when the addition amount is 56.5%. When it is applied to flame-retardant ethylene/vinyl acetate copolymer, when the addition amount of basic magnesium carbonate is 60%, the oxygen index of ethylene/vinyl acetate copolymer reaches 29%.