界面聚合法制备农药微胶囊剂的研究

Pesticide Microcapsules Prepared by an Interfacial Polymerization Method

选取杀螟硫磷作为有效成分,介绍了界面聚合法制备农药微胶囊剂的改进方法,将多异氰酸酯预处理后再进行聚合反应,并与农药微胶囊剂的传统制备方法进行了对比,发现方法改进后,微胶囊的囊皮特性得到很好改善,微胶囊的包药率提高约一倍,达到95%以上,热贮稳定性有很大程度提高,分解率从15%降低到2%左右,释放速度更加缓慢,而且可以通过不同的条件控制释放速度,说明改进后方法制得的微胶囊剂能更好地提高农药的持效性,可以减少施药量。文中还着重研究了多种反应条件对农药微胶囊化的影响,测定了农药微胶囊在水中的释放速度,实验表明:释放速度可以通过界面聚合反应的时间、微胶囊剂粒子的大小、农药与囊材的不同用量比、两种水相单体的不同用量比等因素进行控制和调节,以获得适合实际要求的微胶囊。

Using fenitrothion as active ingredient, an interfacial polymerization method is described for improving the preparation of microcapsule formulations. The polymerization reaction was conducted following pretreatment with excess isocyanate. The capsule walls of the resulting microcapsules were significantly better than those produced by the traditional method, with the new microcapsules holding about twice as much pesticide. High temperature stability was greatly increased. The decomposition rate was decreased from 15 to about 2%. Rate of pesticide release was substantially reduced and could be varied under different conditions. As a result, this improvement in formulation provided significantly increased residual efficacy of the pesticide, allowing reduced application rates. This article also emphasizes research on the effect of different reaction conditions on microcapsule formation, and the measurement of pesticide release from the microcapsule into water. Rate of release could be controlled and adjusted by changes in several factors, such as interfacial polymerization reaction time, microcapsule particle size, pesticide and polymer proportions in the mixture, and proportions of two aqueous phase monomers. The resulting product met the criteria needed in a microcapsule formulation.