| In this article, taking calcium hydroxide and chlorination magnesium as raw materials to produce the magnesium hydroxide flame retardant, the influence of craftwork parameter on the quality during producing magnesium hydroxide was researched. At the same time the producing craftwork, reaction equipment and the synthesis condition which is good for industrialization was studied.During the research on production of the magnesium hydroxide by hydrothermal method, the influence of the concentration of magnesium chloride, injection method, reaction time, reaction temperature, hydrothermal time and hydrothermal temperature on the appearance of magnesium hydroxide was discussed. The magnesium chloride was characterized by SEM, XRD, TG, and BET. The growth of crystal was researched by using the theory of the magnesium chloride structure and crystal growth. By changing reaction equipment, using seeding crystal method and additive mineralizer, the high dispersion superfine magnesium hydroxide flame retardant was produced. The results show:1. The higher purity of magnesium hydroxide flame retardant was produced by using the calcium hydroxide and magnesium hydroxide as raw material, the condition is as follows: adopted calcium hydroxide injection method, the concentration of Calcium hydroxide is 2.2 mol/L, the concentration of Magnesium chloride is 2.5 mol/L, reaction temperature is 60℃, time is 210 min, hydrothermal temperature is 200℃and the time is 8bh.2. Compared with stirred reactor, the thickness of magnesium hydroxide crystal can achieve 80-150 nm by using rotor-stator reactor and hydrothermal modification to produce magnesium hydroxide. The first particle size is above 500 nm. The purity of product is much higher and the micro-strain is lower.3. The first particle size and purity of product can be improved by seeding crystal method, the micro-strain decreased. The fourth thickness of magnesium hydroxide reaches to 100-150 nm, purity is 97.26 % and micro-strain is 2.73×10-3 .4. Taken the calcium hydroxide and magnesium hydroxide as raw material, it is good for the growth of magnesium hydroxide crystal, when the alkalinity of hydrothermal solution is increased. Before hydrothermal process, the potassium hydroxide with concentration of 4 mol/L is added. The thickness of crystal can reach to above 120 nm, the first particle size is long than 500 nm. And the purity and dispersion is better. |
