氨法制备阻燃级氢氧化镁的技术研究

发布时间：2018-04-30 00:24

  本文选题：阻燃剂 + 氢氧化镁　； 参考：《山东大学》2015年硕士论文

【摘要】：氢氧化镁作为一种无机阻燃剂,具有无毒、抑烟、分解温度高等优点,且由于其自身的碱性可以与燃烧过程中产生的酸性有害气体中和,降低环境污染而备受市场青睐。氢氧化镁分解产生氧化镁和水,分解过程吸收大量的热量降低燃烧材料周围的温度,并且释放的大量的水分可以稀释材料周围氧气,分解产物氧化镁也是一种阻燃剂,可以覆盖在高分子聚合物的表面进一步起到阻燃的作用。我国有着世界首屈一指的镁矿资源,为氢氧化镁的发展提供足够的保障。本论文主要是采用氨法制备阻燃级别的氢氧化镁,从形貌、粒径、分散性等方面进行工艺研究,并对自然沉降速率及过滤速率进行测试。由于氨水法制备氢氧化镁的滤液中含有未反应的氯化镁、氨水和生成的氯化铵,所以对氨水法制备氢氧化镁后的一次沉镁母液进行分析处理。滤液中各成分的浓度相对较稀,如果直接蒸发结晶或者盐析结晶制备氯化铵晶体,会消耗大量的能量,所以本文采用氢氧化钙法处理滤液。1.氨法制备阻燃级氢氧化镁实验以3 mol/1六水氯化镁为镁源,氨水为沉淀剂,常温下制备氢氧化镁料浆,然后转移至高压反应釜中进行水热。实验研究了氨水的浓度、滴加速率、搅拌速率、水热时间及分散剂的使用对氢氧化镁形貌、粒径的影响,并对所得的产品进行比表面积、自然沉降速率及过滤速率测试,得出结论：当氨水浓度为4 mol/1,滴加速率为2ml/min,搅拌速率为200 rpm,聚乙二醇-2000和油酸钠为复合改性剂,180℃水热4 h制备出粒径范围700-900 nm,比表面积为19.7 m2/g,分散性良好的氢氧化镁纳米六方片。2.氢氧化钙法滤液处理以氢氧化钙法对氨水沉镁之后的一次滤液进行二次处理,实验考察了氢氧化钙的用量、实验温度、反应时间对镁离子的沉淀率、氢氧化镁的纯度及蒸氨效率的影响,得出结论：当氢氧化钙的用量与理论用量的比为1：1,程序升温90℃反应15 min后再在100℃条件下反应15 min,镁离子的沉淀率和蒸氨效率都达到96%以上,氢氧化镁的纯度为83%。
[Abstract]:As an inorganic flame retardant, magnesium hydroxide has the advantages of non-toxic, smoke suppression, high decomposition temperature and so on. It is favored by the market for its alkalinity and neutralization of acidic harmful gases produced in the combustion process to reduce environmental pollution. Magnesium hydroxide decomposes to produce magnesium oxide and water, the decomposition process absorbs a lot of heat to reduce the temperature around the combustion material, and releases a large amount of water to dilute the oxygen around the material, and the decomposition product, magnesium oxide, is also a flame retardant. It can cover the surface of polymer and further play a role of flame retardancy. China has the world's leading magnesium ore resources, which provides sufficient protection for the development of magnesium hydroxide. In this paper, flame retardant magnesium hydroxide was prepared by ammonia method. The morphology, particle size and dispersion of magnesium hydroxide were studied, and the natural sedimentation rate and filtration rate were tested. Because the filtrate of magnesium hydroxide prepared by ammonia water method contains unreacted magnesium chloride, ammonia water and the generated ammonium chloride, the primary magnesium precipitation mother liquor after the preparation of magnesium hydroxide by ammonia water method is analyzed and treated. The concentration of each component in the filtrate is relatively thin. If the ammonium chloride crystal is prepared by evaporation or salting-out crystallization, a great deal of energy will be consumed, so calcium hydroxide method is used to treat the filtrate. Magnesium hydroxide slurry was prepared by ammonia method with 3 mol/1 magnesium chloride hexahydrate as magnesium source and ammonia water as precipitant, and then transferred to autoclave for hydrothermal treatment. The effects of ammonia concentration, dropping rate, stirring rate, hydrothermal time and dispersant on the morphology and particle size of magnesium hydroxide were studied. The specific surface area, natural sedimentation rate and filtration rate were measured. It is concluded that when ammonia concentration is 4 mol / 1, dropping rate is 2 ml / min, stirring rate is 200 rpm, polyethylene glycol 2000 and sodium oleate are used as composite modifiers for 4 h hydrothermal treatment at 180 鈩，

本文编号：1822241