The agrochemical market is developing towards high-content active ingredients and multi-active ingredient combinations in water-based formulations, thereby improving treatment efficacy. Different active ingredient combinations that have the same efficacy but are based on different mechanisms are key for pest control and increasing yield, and are also a sustainable strategy.

The combination of different pesticides can be achieved through two methods: mixing two or more single agents in the farmer's equipment before spraying, or creating a balanced multi-active ingredient formulation. The barrel mixing method carries considerable risks: the instability of the mixed solution can lead to uneven spraying, and layering in the equipment can prevent normal spraying. Of course, farms in the United States are large and equipped with agricultural experts who can guide the risky barrel mixing of materials and application. For most other farmers in the world, combining active ingredient formulations would be a feasible solution, but this actually shifts the problem to the formulation companies, whose formulation designers will face increasingly new and challenging tasks.

For non-water-soluble active ingredients and conventional pesticide formulation techniques, suspensions (SC) may be a safer, more sustainable, and economical formulation. It consists of one or several active ingredients suspended in water. SC typically contains 5-60% active ingredients, one (or more) dispersants, rheology modifiers, and optionally wetting agents.

The combination possibilities of multi-active ingredient formulations are mainly based on the characteristics of the active ingredients and the adaptability and dispersing power of the dispersants used. Experienced researchers need to consider factors such as: melting point, lipophilicity/hydrophilicity (LogPow), solubility in water, chemical stability at different pH values, and the hardness of the active ingredients during grinding.

During the production of SC, the pumpable initial grinding liquid usually contains different active ingredients, dispersants, wetting agents, defoamers, and water. The grinding liquid is transferred to a wet mill for grinding to achieve a particle size of less than 10 microns. Other additives (such as antifreeze agents, preservatives), as well as the remaining water and rheology modifiers, need to be added to the ground slurry. During the grinding process, the pressure and temperature in the grinding chamber will rise, and even very effective cooling systems often cannot control the temperature well. If there is a significant difference in the melting points of several active ingredients, the low melting point active ingredient will melt, which will damage its performance.

Different active ingredients have different hydrophobic parameters LogPow, so different dispersants are needed. Additionally, if the hardness of the active ingredient particles varies, the harder active ingredients cannot achieve the desired particle size. The feasibility of grinding more than one active ingredient in one step is highly correlated with the efficiency and adaptability of the dispersants. Standard dispersants are anionic polymers (such as sodium lignosulfonate, alkyl naphthalene sulfonates, triphenyl ethylene phenol ethoxylates) or non-ionic polymers (such as EO/PO copolymers, alkoxy triphenyl ethylene phenols). In most cases, these dispersants work well, but when the active ingredient content is very high or the physicochemical properties of the active ingredients vary significantly, the effectiveness of these dispersants diminishes.

To overcome these issues, a new generation of efficient dispersants has been developed: they can reduce the viscosity of the grinding system and improve grinding efficiency. They have good compatibility with other dispersants, thus achieving a synergistic effect, improving suspension stability, self-dispersibility, and extending the shelf life of the formulations.