The choice of surfactants also has a lot of knowledge

2022-04-28 15:24:46

Surfactant is an indispensable and important material in pesticide processing and application. For the selection of surfactants, we should not only consider their compatibility with pesticides, but also consider the factors such as efficiency, stability, appropriate price and safety, so that they can better play the role of pesticides when sprayed with pesticides. At the same time, they also have a certain activity. Therefore, the choice of surfactants also has a lot of knowledge.

Water dispersible granule is an improvement of wettable powder. It is a dosage form developed to prevent dust problems. Its components are the same as wettable powder, but it is a granular preparation diluted with water. The dosage form is a granule with a particle size of about 0.1 ~ 1mm. The preparation will not adhere to the packaging container and is easy to measure due to its good fluidity. In addition, from the perspective of production, it can be processed into high concentration preparations; In terms of use, the container is also easy to handle after use.

It is a representative preparation example of water suspension agent. In addition to water, it is composed of 10% ~ 50% of the original medicine, as well as wetting dispersant, thickener, antifreeze, preservative, defoamer, anti crystallization precipitation agent, etc. As a wetting dispersant, it is anionic and non-ionic surfactant, and the dosage is less than 10%. Compared with wettable powder, suspending agent has better efficacy because of its small particle size, and is safer because there is no dust and dangerous substances. However, due to its physical properties, it also has stability problems, which affect the validity period of the preparation and the manufacturing cost of on-site barrel mixing. At present, it is generally diluted with water on site, and it is planned to develop herbicides sprayed directly with technical drugs without dilution.

The processing method is the same as that of general granules. The extrusion granulation method is the first. There are also fluidized bed granulation method, spray drying granulation method, rotating granulation method, stirring granulation method, etc. Different processing methods have different choices of wetting agent and dispersant. Thus, it has a great impact on the morphology and physical properties of products (dispersibility in water, disintegration in water and hardness), which is also an important topic to improve production capacity and product quality in the future.

Suspension agent is a suspension preparation made by processing insoluble solid technical drugs into fine particles and dispersing them uniformly. Due to the different dispersing media, it can be divided into water suspending agent and oil suspending agent. By wet crushing, the particle size of the suspending agent is usually several μ m。 Different from the suspending agent, it is transparent or translucent, and the particle size is 0.01 ~ 0.1 μ M emulsifying and dispersing system, which has the advantages of good efficacy and preparation stability. In addition, there are water-based oil-based lotion that emulsify and disperse liquid technical drugs insoluble in water, which are called water-based emulsions and suspension emulsions (SE) mixed with suspending agents and emulsions.