原位聚合法制备异恶草酮微胶囊的预聚合成工艺研究

对以脲醛树脂为壁材、用原位聚合法制备除草剂异恶草酮微胶囊的预聚合成工艺进行了研究,考察了单体量比、预聚反应介质pH值、反应温度和时间对微胶囊的结构、包覆效果和包埋率等的影响。结果表明,单体物质的量比n(脲)∶n(甲醛)=1∶2.0、预聚反应pH值为8.0、预聚反应温度为70℃、反应时间为60 min时,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,可制得结构紧密、包覆良好、包埋率为26.7%的球形缓释性固体微胶囊。

Study on pre-polymerization condition of clomazone herbicide microcapsules by in-situ polymerization

Microcapsules with a urea-formaldehyde resin wall were prepared for clomazone herbicide by in-situ polymerization method. The influences of pre-polymerization conditions of urea-formaldehyde, such as molar ratio of urea-formaldehyde, pH value of reaction medium, reaction temperature and reaction time, on the formation of Clomazone herbicide microcapsules, the structure, the size and distribution of particle size and the microcapsulated ratio of core material to the microcapsules were discussed. The results show that molar ratio of urea-formaldehyde n（urea） ： n（formaldehyde）=1 ： 2. 0, pH value is 8.0, reaction temperature is 70 ℃, reaction time is 60 min, the water-solubility of the urea-formaldehyde is good and when it is used in preparation of microcapsule, the microcapsules of fluidizable solid particles with close surface structure wall are prepared. The distribution of particle size is uniform and the ratio of core material to MC is 26. 7%.