Wetting agent is a kind of substance that can reduce the interfacial tension between liquid and solid, increase the contact of the drug-containing liquid on the solid surface of the treatment object (plants, pests, etc.), so that it can be wetted or can accelerate the wetting process. Because the wetting agent has the effect of promoting the wetting and spreading of the liquid on the solid surface, it is also called the wet spreading agent.
Penetrating agent is a type of wetting agent that can promote the penetration of drug-containing components into the treatment object, or enhance the ability of the chemical solution to penetrate the treatment surface into the inside of the object.
Wetting agents and penetrants play an extremely important role in the processing and application of pesticides. At present, most pesticide dosage forms are inseparable from wetting agents and penetrant additives. Such as wettable powder, soluble powder, solid emulsifier, water suspension, oil suspension, dry suspension, granules and water-dispersible granules, etc. In addition, wetting agents and penetrants are essential components of various spray additives required for pesticide application technology.
According to the physical and chemical point of view of surfactants, the wetting effect and osmotic effect of surfactants are essentially different, but it is difficult to strictly distinguish the two in practical application, so the United States Pesticide Regulatory Commission (AAPCO) defines penetrant as a class of wetting agent, that is, penetrant is a generalized wetting agent, but a good wetting agent does not necessarily have good penetrating performance. The essence of the wetting agent is to accelerate the contact between the liquid and the solid interface and increase the contact area, while the penetrant is to increase and promote the liquid to enter the solid. Wetting and permeation properties are two properties that must be possessed in the processing and application of pesticides. Many additives added in the process of pesticide production and use often have both wetting and penetrating properties, so it is difficult to strictly distinguish some pesticide additives into which are wetting agents and which are penetrants, but they may play different leading roles under different conditions.
Most wetting agents have the property of being rewetted by water or liquid after the solid surface has dried. Therefore, wetting agents and penetrants are of great significance to ensure the quality of pesticide formulations. The wetting agent is attached to the surface of the microparticles of the original drug and filler, which can be processed into wettable powder, or added to other solid pesticide preparations, such as soluble powder, solid emulsion, dry suspension agent and water-dispersible granules, etc., so that they have better dispersion and suspension when diluted with water.
The addition of excessive wetting agents other than the wetting of the original ingredient and filler in pesticide processing can reduce the surface tension of the diluent of the agent and increase the wetting, expansion and penetration of the chemical solution on the treated surface. Therefore, adding wetting agents and/or penetrants that exceed the wetting requirements of the original ingredient and carrier in the process of pesticide processing can greatly improve the efficiency of pesticide use. Regardless of the application technology, it is necessary to maximize the contact and absorption of the drug solution by the treatment object in order to give full play to the effect. In pesticide processing, in addition to the above-mentioned solid preparations need to add wetting agents, some liquid preparations such as water suspensions, oil suspensions, etc. also need to add wetting agents and penetrants, reduce the energy of the surface of the spraying liquid droplets, and increase the efficiency of the wetting, spreading and penetration of the spraying solution on the surface of the treatment object.
It should be noted that the wetting agent in the pesticide formulation can reduce the droplet particles of the liquid medicine, shorten the splash distance of the droplets, and reduce the amount of deposition of the liquid on the treated surface due to the decrease of surface tension and have the effect of being rewetted after the treated surface is dried and solidified. Therefore, wetting agents have different effects on the efficiency of different pesticides. For example, for protective pesticides with low activity, high water solubility, and easy degradation in aqueous solution, wetting agents have adverse effects. Because reducing the amount of liquid deposition and increasing the effect of being leached by water will reduce the efficacy of the drug. Conversely, for highly active and systemic pesticides, wetting agents help to evenly coat a small amount of chemicals on the treated surface and improve efficiency. In today's situation where new pesticides are developing more and more active and the use per unit area is getting lower and lower, it is even more important to research and utilize high-performance wetting agents and penetrants.
