Emulsifiable concentrates (EC), despite the evolution of other up to date formulations, are still used worldwide because of their simple manufacturing process and lower cost. For application in the field, such formulations are diluted in water, forming an oil-in-water emulsion which allows a homogeneous distribution of active ingredients on crops.
Emulsifiable concentrates have some advantages when compared to other formulations:
- Low cost of production
- Very simple technology
- Often better biological activity
Some disadvantages are:
- High amount of solvents
- Often low flash point
- High dermal toxicity
- Packaging disposal
These disadvantages can be partially overcome by choosing high flash point solvents and a with new packaging technology such as "gel in water soluble bag". However, the formulations will always contain solvents.
Emulsifiable concentrates generally contain :
- Active ingredients
- Solvents - co-solvents
- Stabilizers, stickers, antifoam
Active ingredients have to be chemically stable and soluble within the solvents to obtain a suitable active content.
Solvent - co-solvents
Aromatic paraffin, solvents such as Xylene and Solvesso are still widely used in EC.
To ease the storage, handling and transportation, high flash point solvents such as Solvesso 150 and Solvesso 200 are used along with new solvents with a more favorable eco-toxicological profile.
When the solubility of actives in aromatic solvents is not sufficient to obtain a suitable active content, it is necessary to add a polar solvent. In the past the most commonly used co-solvents were cyclohexanone, isophoron and N-methylpyrrolidone, but nowadays they have been replaced by a new generation of solvents with a very favorable eco-toxicological profile.
Solvay has developed Rhodiasolv Polarclean, an ester amide powerful polar, water soluble solvent with outstanding solvency properties.
The solubility of various agricultural actives in Rhodiasolv® PolarClean compared to others:
- Harmful but performant agrochemical solvent such as N-M Pyrrolidone
- Other amide commonly used in agrochemicals (Rhodiasolv ADMA 10 and ADMA 810)
- Other ester such as 2 ethyl hexyl lactate
In the formulation, one or more hydrophilic nonionics surfactants will have to be balanced with lipophilic anionic one.
These are single surfactants of hydrophilic (nonionic) or lipophylic (anionic) activity to be balanced in the formulation in order for a suitable HLB and optimum emulsifiability to be achieved. Their balancing is sometimes critical and the proper ratio of emulsifiers must be strictly applied.
These are blends of anionic and nonionic surfactants used as pairs. Because of their compositions the balance is easier and consequently they offer a wide range of applications reducing the number of required emulsifiers. Normally formulations are less sensitive to variations in water temperature and hardness. Blended emulsifiers are also used for some specific formulations which could be difficult to achieve with straight emulsifiers.
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