Application of modified magnesium hydroxide in PP

Magnesium hydroxide is a very widely used flame retardant. Although the high filling amount of magnesium hydroxide will reduce the processing performance of flame retardant materials, it also has high smoke dissipation ability. Meanwhile, the surface of polar inorganic material is modified to non-polar after magnesium hydroxide is modified by stearic acid, which improves the compatibility and processing performance.

Polypropylene (PP), as one of the five general-purpose plastics, has the advantages of chemical resistance, stress cracking resistance, low density, good electrical insulation, and excellent mechanical properties. Secondly, polypropylene is widely used in various fields because of its low price, easy processing and high heat deflection temperature.

In recent years, various industries have put forward higher requirements for polypropylene properties such as flame retardancy and mechanical strength. The addition of modified magnesium hydroxide in polypropylene can effectively improve its own flame retardant properties, but the mass fraction of magnesium hydroxide filler can play a flame retardant role only when it reaches a high content. However, it will cause the mechanical properties and processing properties of polypropylene material to decrease.

Magnesium hydroxide adopts stearic acid for surface modification, and its mechanism of action relies on the alkaline group on the surface of inorganic filler and the hydroxyl group of stearic acid (COOH-), and the resulting stearic acid will stay on the surface of inorganic particles and play the role of surface modification. Meanwhile, the hydrophobic groups reaching the solvent will produce a spatial site resistance effect and improve the dispersion of the particles in the organic solvent. Therefore, the mechanical properties such as plasticity and impact resistance of polypropylene materials can be optimized while ensuring the flame retardancy of the material.