Pesticide dry suspension is a formulation developed in the 1970s, and has become one of the basic processing formulations. Dry suspension agent (hereinafter referred to as SC), also known as water suspension agent, colloidal suspension agent and concentrated suspension agent, is used to disperse insoluble or insoluble technical drugs into water under the action of surfactant and other additives to form a uniform and stable coarse suspension system. Because its dispersion medium is water, the suspension agent has the characteristics of low cost, safe production, storage, transportation and use, and is easy to mix with water and use. Compared with the pesticide formulation with organic solvent as the medium, it has the advantages of less impact on the environment and less harm.
The preparation technology of dry suspension agent involves pesticide chemistry, pesticide preparation, physical chemistry, chemical machinery and other disciplines, and the research and manufacturing technology is relatively complex. Although the dry suspension agent appeared as early as the 1970s, due to the impact of the development of grinding machinery, surfactant and other technologies, its promotion scale is still difficult to compare with the bulk dosage forms such as emulsifiable concentrates and wettable powders. The varieties currently developed, especially most of the domestic dry suspension products, have poor physical stability, are prone to stratification and precipitation during storage, and the effective ingredients of pesticides are difficult to disperse evenly, or even agglomerate and cannot be poured out of the packaging, which seriously affects the promotion and use of dry suspension in agricultural production.
The processing equipment and process of pesticide dry suspension agent are very important, which often affect the quality of products.
The main contents of the research on the processing technology of dry suspension agent are:
1. According to the properties of the selected pesticide active ingredients, a processing method is determined, that is, the process route is determined;
2. Select appropriate processing equipment;
3. Determine the feeding sequence of each component.
There are two main processing methods for pesticide dry suspension. One is superfine grinding method (also called wet grinding method), and the other is condensation method (also called hot melt dispersion method). And the processing of agricultural drug water suspension agent basically adopts the ultra-fine grinding method.
In order to ensure the performance of pesticide dry suspension products, China's chemical industry standard, "Specifications for the Preparation of Pesticide Dry Suspension Product Standards" (HG/T2467.5-2003), stipulates that the general pesticide suspension products should control nine indicators, including the content of effective ingredients, the limit of related impurities, the pH or pH range, suspension rate, dumping, wet screening test, lasting foaming, low temperature and thermal storage stability. These indicators can ensure the content of effective ingredients and some properties of pesticide suspension products. However, in order to ensure its use performance, some necessary items of pesticide suspension agent should be controlled. These items include: centrifuge stability, viscosity and adaptability to water quality tests.
Pesticide dry suspension agent is currently recognized as one of the environment-friendly pesticide preparations, but its share in the pesticide market in China is still very limited, and pesticide additives are still one of the factors affecting the development of this preparation. With the entry of foreign additives into the Chinese market and the development of domestic pesticide additives, the development of pesticide dry suspension agents will be rapidly developed.