Study On Preparation And Stability Of Pentasulfame Dispersible Oil Suspension

With the development of pesticide formulations in China in the direction of safety and environmental protection,the proportion of dispersible oil suspended in pesticide formulations has increased year by year.According to the definition of the Food and Agriculture Organization of the United Nations,a dispersible oil suspension agent is a solid active ingredient of a pesticide that is insoluble in a non-aqueous medium(mainly including an oil-based medium or a solvent medium),and is processed into a surfactant and an additive.The fine particles are suspended in a non-aqueous medium to form a highly dispersed,stable suspension liquid preparation,and the pesticide dosage form used is diluted with water.In this paper,pentasulfame was used as the research object.The effect of different factors on the stability of suspension system was studied by screening 2.5% penoxsulam dispersible oil suspension formulation.The main findings are as follows:1 2.5% screening of dispersible oil suspension formulations,(1)The emulsifier was initially screened by observing the dispersion effect in water.The single emulsifier and the emulsifier after compounding were compared.By optimizing the combination,it was determined that 1985: Pluronic PE10500=5:1 is a suitable composite emulsification.Agent,the dosage is 18%(2)The dispersant was initially screened by the flow point method.According to the Zeta potential and particle size,the best type and amount of dispersant were determined.Combined with rheological parameters and physical and chemical properties after heat storage,the type of dispersant was determined to be OD-10,and the dosage was 5%.(3)Determine the thickener as organic bentonite in combination with the appearance state,oil separation rate and dispersibility,and the dosage is 1.5%.2 The Zeta potential,particle size,viscosity,dispersion performance and suspension rate of different emulsifiers and dispersants for 2.5% penoxsulam dispersible oil suspension were studied.(1)The emulsifier is 1985: Pluronic PE10500 = 5:1 compounding ratio,the dispersing agent OD-10 is 5%,and the prepared dispersible oil suspending agent has the best dispersion effect in water at 35 °C.(2)Controlling the particle size and viscosity of the dispersible oil by the amount of dispersing agent,so that the original drug particles are stably suspended,which of great significance for the development of dispersible oil suspension.3 The effects of dispersant and thickener on the rheological properties of 2.5%penoxsulam dispersible oil suspension system were studied.The rheology and thixotropy of the system were discussed.(1)The apparent viscosity of 2.5% penoxsulam dispersible oil suspension decreased with the increase of shear rate,and it was a "shear-thinning" non-Newtonian fluid,which accorded with the Herschel-Buckley rheological model.(2)The amount of the dispersant added does not change the rheology type of the system.However,as the dispersant content in the system increases,the viscosity appears to decrease first and then increase,and this property can be utilized to determine the dispersant content.(3)After adding organic bentonite,the network structure formed can adjust the yield value and thixotropy of the system.The oil removal rate after the preparation of the preparation is lowered.As the temperature increases,the network structure between the particles collapses,resulting in a smaller yield value and an increased oil separation rate.