分散、乳化条件及成囊工艺对二甲戊灵微胶囊形成状态的影响

Effect of Dispersing-emulsifying Measures and Encapsulation Parameters on the Appearance of Pendimethalin Microcapsule

研究了分散、乳化条件及成囊工艺对以脲醛树脂为壁材采用原位聚合法制备二甲戊灵微胶囊状态的影响。讨论了不同乳化剂及其配比、不同分散乳化时间、搅拌速度、酸化时间和固化温度对微胶囊包封率、粒径大小及分布情况的影响,最终确定以聚丙烯酸钠(PAAS)和苯乙烯-马来酸酐(SMA)按4∶1(质量比)混合作乳化剂,1 500r/m in搅拌,分散乳化60m in,酸化90m in,50℃固化90m in作为制备二甲戊灵微胶囊的优化工艺条件。在此条件下可以得到平均粒径10μm左右、粒度分布均匀的球形微胶囊,包封率在99%以上。

Microcapsules of pendimethalin with a urea-formaldehyde resin wall were prepared by an in-situ condensation polymerization reaction in aqueous medium. Several encapsulating parameters including dispersing and emulsifying agent, emulsification time, stirring speed, acidification time and curing temperature on microcapsule appearance quality such as encapsulation rate ,particle size,and size distribution were investigated. Optimal reaction conditions were as follows：PAAS and SMA at weight ratio of 4 ： 1, stirring for emulsifying at speed of 1 500 r/min and lasted 60 min, acidifying for 90 min, the curing temperature under 50℃ for 90 rain. Under these conditions, the mean particle diameter of 10 μm,uniform and spherical microencapsules of pendimethalin were obtained, their encapsulation rate was above 99%.