We know that both magnesium hydroxide and aluminum hydroxide can be used as flame retardants, so what is the relationship between them? What are the differences? Let’s take a look together.
According to the chemical composition, flame retardants can be divided into two categories: organic flame retardants and inorganic flame retardants. Organic flame retardants are further divided into two series: phosphorus and halogen. Due to the disadvantages of high toxicity of decomposition products and large smoke, organic flame retardants are gradually being replaced by inorganic flame retardants. Aluminum hydroxide and magnesium hydroxide are the two most important inorganic flame retardants, and their common features are environmental friendliness, flame retardancy, smoke suppression and filling functions. Aluminum hydroxide is one of the earliest applied inorganic flame retardants. As a flame retardant, aluminum hydroxide has the characteristics of good stability, non-toxicity, no corrosive gas, long-lasting flame retardant effect, etc., and the product has high whiteness.
Magnesium hydroxide flame retardant is an inorganic flame retardant that is being actively developed at home and abroad. In addition to the above advantages of aluminum hydroxide, its thermal stability and smoke suppression performance are significantly better than aluminum hydroxide. Dehydration reaction of magnesium hydroxide occurs above 350 degrees Celsius, and the heat absorption of magnesium hydroxide is 17% higher than that of aluminum hydroxide, which also helps to improve flame retardant efficiency. At the same time, magnesium hydroxide is more suitable for polymers with high processing temperatures. It can be seen that different flame retardants have different characteristics and uses.
With the increase of polymer processing temperature, aluminum hydroxide is easy to decompose, reducing the flame retardant effect. Compared with aluminum hydroxide, magnesium hydroxide has the following advantages:
1. The thermal decomposition temperature of magnesium hydroxide reaches 330°C, which is 100°C higher than that of aluminum hydroxide, so it is beneficial to increase the processing temperature of plastics, accelerate the extrusion speed, and shorten the molding time;
2. Magnesium hydroxide has a strong neutralization ability with acids, and can quickly neutralize acid gases SO2, NOx, CO2, etc. produced during the combustion of plastics;
3. Magnesium hydroxide has high decomposition energy, which is beneficial to absorb combustion heat and improve flame retardant efficiency;
4. Magnesium hydroxide has strong smoke suppression ability, low hardness, and low friction to equipment, which helps to prolong the life of production equipment.