MAGNESIUM HYDROXIDE FIRE RETARDANT NANOPARTICLES AND PRODUCTION METHOD THEREOF

摘要

Magnesium hydroxide fire retardant particles, including those which are surface-treated, having a hexagonal plate-like structure with a specific surface area not exceeding 20 m2/g, an average diameter of secondary particles not exceeding 2 microns, the diameter of 10% of secondary particles not exceeding 0.8 microns, the diameter of 90% of secondary particles not exceeding 5 microns, a longitudinal dimensions of primary particles of between 150 and 900 nanometers and a thickness of between 15 and 150 nanometers. A first stage of producing said particles involves reacting an aqueous solution of magnesium chloride with an alkaline agent at a temperature not exceeding 100°С and at atmospheric pressure, with a molar ratio of OH-:Mg++ ions equal to (1.9-2.1):1. A second stage involves the hydrothermal recrystallization of Mg(OH)2 particles at a temperature of 120-220°C and a pressure of 0.18-2.3 MPa for a period of between 2 and 24 hours. The reacting mass is periodically subjected to hydro-impacts from superheated vapor having a temperature of 160-240°С and a pressure of 0.6-3.3 MPa. The invention allows for producing magnesium hydroxide particles having adjustable dimensions, for applying same to polymer matrices without compromising the mechanical properties of the polymers.