Method for improving performance of magnesium hydroxide flame retardant

Magnesium hydroxide is currently the most studied fastest-growing green flame retardant. It has no secondary pollution, good thermal stability, no volatility, no precipitation, no toxic gases, no corrosion of processing equipment, significant smoke elimination effect. , High-efficiency substrate carbon formation many other advantages, rich in magnesium resources. However, the magnesium hydroxide prepared by the conventional method has strong polarity hydrophilicity, the crystal grains tend to be secondary agglomerated, the dispersibility is poor, the compatibility with the non-polar polymer material is extremely poor, the interface is difficult to form Good bonding adhesion, so as the content of magnesium hydroxide in the polymer material increases, its processing performance mechanical properties also decline sharply, so that its application is limited. In order to make magnesium hydroxide better used for flame retardant polymer materials, there are mainly the following methods:

(1) Ultra-fine particle size. At the processing temperature of the polymer material, magnesium hydroxide is present in the system in the form of particles. Generally speaking, when the filling amount is the same, the finer the particle of magnesium hydroxide, the more uniform the dispersion the more obvious the flame retardant effect. , The smaller the negative impact on the physical mechanical properties of the material, the plasticity of the rigid particles will even be enhanced.

(2) Change the crystal structure of magnesium hydroxide to prepare special morphology (hexagonal flakes). Magnesium hydroxide mixed at normal temperature is usually hydrothermally modified. In a specific high-temperature high-pressure aqueous solution, magnesium hydroxide is used for crystallization reorganization. The structure morphology of the crystal are changed through the process of dissolution-recondensation-crystal growth. The hexagonal flaky magnesium hydroxide has low surface polarity surface energy, good miscibility with polymer materials, has unique advantages as a flame retardant. In addition, hexagonal flaky magnesium hydroxide is easy to mix with resin also has reinforcement properties, so it has good mixing processing properties.

(3) Surface modification treatment of magnesium hydroxide. Magnesium hydroxide is a highly polar inorganic compound with hydrophilicity. Even with very dry magnesium hydroxide, there is moisture in the crystal that cannot be ignored, so magnesium hydroxide is very It is easy to reunite has poor compatibility with polymer materials, making the surface of the substrate defective, rough dull. After modification with magnesium hydroxide, the crystal grains eliminate the surface polarity, which improves the dispersibility, compatibility affinity of the polymer material, has better flame retardant properties, also acts as a reinforcing agent Function, improve the mechanical strength of polymer materials.

(4) Develop composite flame retardant of magnesium hydroxide. Choose other flame retardants to mix with magnesium hydroxide, use flame retardant synergies, effectively improve flame retardant performance. In flame retardant technology, the synergistic effect can only produce more effective flame retardant systems, but also make it possible to reduce the amount of chemical agents used in other flame retardants, can improve the flame retardant efficiency of the flame retardant.