除草剂稀禾定微胶囊的制备

用原位聚合法以脲醛树脂为壁材,制备除草剂稀禾定微胶囊.考察了预聚反应介质pH值、预聚反应温度、缩聚反应催化剂及缩聚反应终点pH值对微胶囊的结构、包覆效果和包埋率等的影响.结果表明:预聚反应pH值为8.0,预聚反应温度为70℃,反应时间60 min,可得到以二羟甲脲为主的水溶性透明黏稠预聚物,用此预聚物进行缩聚反应,以NH4Cl做缩聚催化剂,芯皮比为1∶1.5(质量比),控制缩聚反应终点pH值为3.0,可制得结构紧密、包埋率为30.6%的流动性球形缓释性固体微胶囊.

Preparation of Sethoxydim Herbicide Microcapsules

Microcapsules with a urea-formaldehyde resin wall were prepared for sethoxydim herbicide by in-situ polymerization method.The influencing factors,such as pH value of pre-polymerization reaction medium,reaction temperature,catalyst,the end pH value,on the formation of sethoxydim herbicide microcapsules,the structure and the ratio of core material to the microcapsules were discussed.The results show that pH value of pre-polymerization reaction medium was 8.0,reaction temperature was 70 ℃,reaction time was 60 min,the water-soluble polymerization of urea-formaldehyde was good,under these conditions of polymerization: NH4Cl could be used as acid catalyst,the core-skin ratio was 1∶1.5,the end point pH value was 3.0,the microcapsules of fluidizable solid particles with close surface structure wall were prepared,and the ratio of core material to microcapsules was 30.6%.