Preparation of magnesium hydroxide flame retardant via MgCl₂-NH₃·H₂O synthesis and hydrothermal modification treatment methods

In order to solve the problem that the Mg(OH)₂ is incompatible with the polymer, the two steps reaction of high dispersive Mg(OH)₂ preparation, synthetic reaction and hydrothermal modification treatment, was studied. The effect of the synthetic reaction temperature, hydrothermal modification temperature and time was investigated for preparation of Mg(OH)₂ flame retardant with large crystalline structure and small specific surface area. The experimental results indicate that the growth direction of Mg(OH)₂ crystal is changed and the regular hexagonal plates of Mg(OH)₂ with uniform particle size and high dispersion characteristic are formed after the hydrothermal modification treatment. With the increasing MgCl₂ concentration and/or feeding excessive NH₃·H₂O, percent conversion rates of raw materials are discussed. The results show some new technologies should be studied for increasing percent conversion of raw materials when synthetic reaction is equivalent.