In modern flame retardant skills, the compound skills of flame retardants is a very important aspect. In addition to adhering to the characteristics of environmental protection, the inorganic composite flame retardant system also has the characteristics of multiple flame retardants. Therefore, the composite synergy of different types of inorganic flame retardants has broad prospects for the further use of flame retardant skills.
Magnesium hydroxide is a kind of inorganic flame retardant filler for polymer-based composite materials with good application prospects. Like aluminum hydroxide, magnesium hydroxide flame retardants rely on chemical decomposition to absorb heat and release water when heated to play a flame retardant role. Therefore, it has non-toxic, low smoke, and magnesium oxide formed after decomposition is chemically stable. Produce secondary pollution and other advantages. However, compared with halogen-containing organic flame retardants, in order to achieve a considerable flame retardant effect, the filling amount should generally reach more than 50%. Because magnesium hydroxide is an inorganic substance, the compatibility between the surface and the polymer base material is poor. Such a high filling amount, if it is not subjected to surface modification treatment, after filling into the polymer material, it will lead to composite materials The mechanical properties are reduced. Therefore, it must be surface-modified to improve its compatibility with the polymer base material, so that the mechanical properties of the filler material do not drop, and even the mechanical properties of the material are improved.
The advantages of magnesium hydroxide over aluminum hydroxide are as follows:
(1) The thermal decomposition temperature of magnesium hydroxide is 330 ° C, which is 100 ° C higher than aluminum hydroxide, which is more conducive to increasing the processing temperature, speeding up the extrusion speed, and shortening the molding time.
(2) Magnesium hydroxide and acid have strong neutralizing ability, and can neutralize acidic gas, such as CO2, NOX, SO2, etc. generated by the polymer during the combustion process relatively quickly.
(3) The decomposition energy of magnesium hydroxide is high, which helps to absorb the heat of combustion and improve the flame-retardant efficiency.
(4) Magnesium hydroxide has low hardness, strong smoke suppression ability, and low friction to equipment, which helps to extend the life of production equipment.
According to chemical composition, flame retardants can be divided into two categories: organic flame retardants and inorganic flame retardants. Among them, organic flame retardants are also divided into halogen-based and phosphorus-based. However, due to the shortcomings of organic flame retardants such as large smoke and high toxicity of decomposition products, the certificate has gradually been replaced by inorganic flame retardants.
In addition, the main varieties of inorganic flame retardants are magnesium hydroxide flame retardant, aluminum hydroxide, tin oxide, antimony oxide, molybdenum oxide, red phosphorus, ammonium molybdate, zinc borate, and the like. Among them, magnesium hydroxide and aluminum hydroxide absorb large amounts of heat due to decomposition, and H2O produced by the decomposition can block the air. The oxides generated by the decomposition are high-temperature resistant substances. In addition to the role of combustion, it can also play a role of filling. At the same time, magnesium hydroxide is also non-drip, non-toxic, smokeless, non-volatile, does not produce corrosive halogens and harmful gases, and has long-lasting effects.