Wettable powders are powdery formulations that can be wetted by water when added to water. Surfactant wettable powder is composed of pesticide original drug, filler, wetting agent, dispersing agent and stabilizer. The filler must be highly absorbent, and the solid formed after absorbing the original drug can be easily crushed. Usually, clay, diatomaceous earth and silicon dioxide are used as fillers. These fillers make the pesticide technical maintain a certain thermal stability during storage, and the filler itself has good suspending performance in water without flocculation. Since many organic pesticides are hydrophobic substances and cannot be wetted by water, a wetting agent should be added to the wettable powder, and the wetting agent should reach the standard that the wettable powder can be wetted by water within 1-2 minutes. In order to make the powder quickly disperse in water, a certain amount of dispersant should be added to make the powder have good and long-term suspension performance after being diluted with water. The suspension rate of the wettable powder is required to reach more than 70%.
Microemulsion pesticides use the action of surfactants to uniformly disperse liquid oily pesticides in water in an ultra-fine state (particle size 0.1-0.01 μm) to form a transparent or translucent homogeneous body. Microemulsion is a thermodynamically stable dispersion system formed spontaneously. Surfactant is the key component in the preparation of microemulsion. At present, there is no complete theoretical basis for the selection of emulsifiers for microemulsions, and many formulation works are based on the mixed film theory and solubilization theory, and are comprehensively considered with reference to the HLB value and critical micelle concentration of surfactants.
The original pesticide is dissolved in water, and suitable additives are added to form a homogeneous and stable true solution. This preparation is called an aqueous solution or simply aqua. The active ingredient in the aqueous dosage form is in molecular or ionic state, with a diameter of less than 0.001 μm. This dosage form is easy to process, has low phytotoxicity, low toxicity, easy dilution, safe and convenient use, and has good biological effects. However, most pesticides are generally insoluble or insoluble in water, and there are not many varieties of original drugs that can be processed into water preparations. In order to improve the quality of the water preparation and improve the efficacy, the preparation of water preparation pesticides needs to add appropriate surfactants, but the auxiliary agents should not interact with the active ingredients of the pesticides, nor affect the appearance of the water preparations, that is, bring turbidity, delamination, precipitation.
The selection of any adjuvant should consider the biological activity of the original pesticide. Different water-based pesticides need different adjuvants. Only by matching the appropriate adjuvant to the water agent, can the liquid medicine not be lost, and it will not cause the liquid medicine to not fully spread on the leaf surface.
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