高分散性片状阻燃型氢氧化镁的制备

Synthesis of Flaky Flame-retardant Magnesium Hydroxide with High Dispersion

以轻烧氧化镁为原料,通过水化水热法制备高分散性片状氢氧化镁.考察了不同的水化温度、水化时间、水热时间和分散剂体系对氢氧化镁材料形貌的影响.采用X射线衍射(XRD)、扫描电子显微镜(SEM)、全自动氮物理吸附仪(ASAP)等对所制得的氢氧化镁颗粒的物相、形貌和比表面积进行了分析.结果表明,通过水热反应控制和分散剂的加入,可以得到高分散性片状的阻燃型氢氧化镁.

In this study, Flaky magnesium hydroxide with highly dispersion was prepared from light-burned magnesia by hydration hydrothermal method. The influence of different hydration temperature, hydration time, hydrothermal time and dispersant system on the morphology of magnesium hydroxide material was investigated systematically. The morphology, phase composition and specific surface area of magnesium hydroxide were investigated by X-ray diffraction （XRD）, scan- ning electronic microscope （SEM）, and accelerated surface area and porosimetry （ASAP）. The highly dispersed flaky flame-retardant magnesium hydroxide was further surface modified and then its flame retardation property was tested. Results demonstrated that the light-burned magnesium oxide could completely transform to magnesium hydroxide at 90 ℃ for 1 h hydration, and the products were uniform hexagonal flake with thickness about 20-30 nm. When the hydrated magnesium hydroxide further hydrothermal reacted at 160 ℃ for 23 h, the crystal structure changed. According to the XRD pattern, （100） face appeared more, while the stronger （001） face became less visible, and the ratio oflool/Ilot was about 1.80. It indicated that controlling hydrothermal reaction condition would change the growth direction of magnesium hydroxide crystal, and the surface polarity and internal stress of the crystals decreased when the hydrothermal reaction time was extended. SEM observation indicated that the thickness of magnesium hydroxide hexagonal flake increased to 80- 100 nm after hydro- thermal reaction. Moreover, the dispersion of the product was enhanced and the aggregation was reduced after further surface modification and regulation by dispersant. Thus, the specific surface area was 9.1668 m^2/g. When the modified highly dispersed magnesium hydroxide was added to the PVC composite system, the oxygen index of the system was 27.3. Under the same condition, the oxygen index of ordinary magnesium hydroxide and calcium carbonate were 25.7 and 22.7, respectively. This result declared that the addition of highly dispersed magnesium hydroxide could enhance the flame retardancy of PVC composite system.