利用酯化淀粉和油酸甲酯制备高效氯氟氰菊酯水乳剂

以辛烯基琥珀酸淀粉钠和油酸甲酯分别为替代乳化剂和溶剂,采用浓缩乳化法制备了高度稳定的2.5％高效氯氟氰菊酯水乳剂,通过测定乳液油滴粒径分布,结合乳液外观研究了乳化方法、预处理液中辛烯基琥珀酸淀粉钠质量分数、转速和剪切时间等工艺条件对乳液稳定性的影响.研究结果表明,辛烯基琥珀酸淀粉钠对油酸甲酯具有较好乳化效果,以其为乳化剂可制备高度稳定的2.5％高效氯氟氰菊酯水乳剂,油滴平均粒径在1.2 μm左右,且加速试验即(54±2)℃密封14 d]和常温储存6个月后平均粒径仅增长了0.1～0.3μm,外观无变化；采用浓缩乳化法且预处理液中辛烯基琥珀酸淀粉钠质量分数在15％～25％时乳液稳定性较好,提高转速可降低油滴平均粒径,但对乳液均一性无显著影响,延长剪切时间对油滴平均粒径影响不大,但有利于提高乳液均一性；辛烯基琥珀酸淀粉钠为乳化剂制备的高效氯氟氰菊酯水乳剂稳定性优于常规水乳剂.

Preparation of Lambda-Cyhalothrin Oil-in-water Emulsion with Esterified Starch and Methyl Oleate as Emulsifier and Solvent

In order to provide a reference for octenyl succinic anhydride(OSA)-modified starch and methyl oleate used in green pesticide preparations,the formulation of the lambda-cyhalothrin oil-in-water emulsion with OSA-modified starch and methyl oleate as emulsifier and solvent was studied.Furthermore,the effects of different processing parameters,including the concentration of pretreating fluid of OSA-modified starch,rotational speed and shearing time on the stability of emulsion were studied by measuring oil droplet diameter distribution.Results demonstrated that OSA-modified starch had excellent emulsification ability to methyl oleate.High stable emulsions(2.5%) could be prepared with OSA-modified starch.The mean droplet diameters of emulsion were about 1.2 μm,and increased by only 0.1~0.3 μm after storing at 25 ℃ for 6 months or at(54±2) ℃ for 14 days,and approximately 100% of the oil remained stable in the emulsion.Higher stable emulsions could be prepared by emulsification at high viscosity with mass fraction of pretreating fluid of OSA-modified starch in the range of 15%~25%.Smaller oil droplet diameters were obtained when the rotational speed was increased,which had no significant effect on homogeneity of emulsions.On the other hand,an increase of the shearing time reduced the span of oil droplet diameter distribution,but had no significant impact on the mean oil droplet diameter.Lambda-cyhalothrin oil-in-water emulsion prepared with OSA-modified starch had a better stability than the conventional emulsions.The results of this study show that OSA-modified starch and methyl oleate can be used as an effective emulsifier and solvent for the environment-friendly lambda-cyhalothrin oil-in-water emulsion formulations.