有机-水两相体系制备超细氢氧化铝

Preparation of superfine aluminum hydroxide in organic-water mixed solvent.

以水为介质沉淀法制备超细氢氧化铝时，由于水的存在形成架桥羟基，干燥时会聚集形成硬团聚，为克服这种现象，提出以正丁醇为有机相，AlCl3·6H2O为原料，氨水为沉淀剂的有机-水两相体系沉淀氢氧化铝的工艺，以烷氧基取代水的羟基形成软团聚，降低了粉体硬团聚．在此基础上，结合正丁醇共沸蒸馏和硅烷偶联剂进行表面改性的方法制备出超细氢氧化铝粉体．通过对制备过程中各种操作参数及影响因素的考察，获得了制备的最佳条件：氨水浓度以6．7mol·L^-1为宜，约6％的KH-550硅烷偶联剂，反应温度20～25℃，反应时间25～35min，经过共沸蒸馏和120～125℃条件下干燥，得到平均粒径为619．3nm的超细氢氧化铝．

The aluminum hydroxide synthesized by precipitation method in aqueous solution would agglomerate easily when dried because of hydroxyl bridge. To solve this problem, a technique of preparing superfine aluminum hydroxide in organic-water two-phase system, which used n-butanol as reaction medium, AlCl4·6H2O as material and ammonia as precipitator, was put forward. Therefore, alkoxyl replaces hydroxyl to form soft agglomeration, leading to sharp decrease in hard agglomeration. Based on this, silane coupler KH-550 was used as surface modifier and azeotropic distillation were adopted in the process. The optimal technologual conditions were as following： ammonia 6.7 mol · L^-1 , was poured into the reaction system, the amount of silane coupler KH-550 was 6% of the theoretical product, reaction temperature and time were 20-25℃, 25-35 min, respectively. The heterogeneous azeotropic distillation was used, and then the product was dried at 120- 125 ℃. The mean diameter of superfine aluminum hydroxide was 619.3 nm.