Common dispersion problems and solutions for the preparation of pesticide suspensions using sand mills

1. The viscosity increases during the grinding process. The main reason is that the dispersant is not easy to deform, has poor adsorption, and is easy to fall off the surface of the particles. The original medicine contains low melting point and high boiling point substances. Additives with wetting and dispersing composite functions, especially three-dimensional polymer surfactants, can be used to improve the fastness of adsorption, the thickness of the adsorption layer, increase the lubrication between particles, and increase the content of the original drug.

2. Foaming during the grinding process. The main reason is the wrong choice of dispersant. A wetting and dispersing agent with a certain anti-foaming function can be used, and a small amount of anti-foaming agent can be added. Excessive organosilicon defoamer is easy to cause system instability, and the water is separated.

3. The viscosity of the system is high after grinding. The main reason is that the choice of additive system is basically correct, but it is necessary to add a dispersant that has the effect of wetting and reducing viscosity. A wetting and dispersing agent with better lipophilicity can be used to control the viscosity at 200-400mpa.s.

4. Heat storage paste or viscosity increase after grinding. The main reasons are improper choice of antifreeze, improper choice of anti-settling, and improper choice of wetting and dispersing agent. Polymer surfactants can be used to achieve multi-point and multi-level adsorbents, reduce the area of "bare" particles, select suitable antifreeze agents, reduce the solubility of dispersants or particles in the continuous phase, replace anti-settling agents, and reduce induced crystallization Possibility of choosing a polymer surfactant to reduce the solubility of the original drug in low-molecular additives.